| Immune evasion by neocartilage-derived chondrocytes: Implications for biologic repair of joint articular cartilage.
November 3, 2009 at 7:38 am
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| | Immune evasion by neocartilage-derived chondrocytes: Implications for biologic repair of joint articular cartilage. Stem Cell Res. 2009 Sep 25; Authors: Adkisson HD, Milliman C, Zhang X, Mauch K, Maziarz RT, Streeter PR Degeneration of joint articular cartilage is a leading cause of disability worldwide, and is due in large part to the fact that adult articular cartilage is unable to undergo effective intrinsic repair. To overcome this barrier, we have developed a tissue engineering strategy which harnesses the superior anabolic activity of juvenile chondrocytes to produce a scaffold-independent, living neocartilage graft. Preclinical studies demonstrate that bioengineered neocartilage survives allogeneic and xenogeneic transplantation, suggesting the utility of universal donor-derived neocartilage for joint repair. However, the mechanism underlying neocartilage transplant tolerance remains poorly understood. We show here that neocartilage-derived chondrocytes are unable to stimulate allogeneic T cells in vitro, and they do not constitutively express cell surface molecules required for induction of T cell immune responses, including major histocompatibility complex (MHC) Class II antigens and costimulatory molecules B7-1 and B7-2. Additionally, chondrocytes suppress, in a contact-dependent manner, the proliferation of activated T cells, with suppression associated with chondrocyte expression of multiple negative regulators of immune responses, including B7 family members (B7-H1, B7-DC, B7-H2, B7-H3, and B7-H4), chondromodulin-I and indoleamine 2,3-dioxygenase. Thus, the survival of transplanted bioengineered neocartilage may depend on both passive and active mechanisms of immune evasion. PMID: 19880363 [PubMed - as supplied by publisher] |
| The repair of large segmental bone defects in the rabbit with vascularized tissue engineered bone.
November 3, 2009 at 7:38 am
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| | The repair of large segmental bone defects in the rabbit with vascularized tissue engineered bone. Biomaterials. 2009 Oct 30; Authors: Zhou J, Lin H, Fang TL, Li X, Dai WD, Uemura T, Dong J Management of segmental bone defects is a considerable challenge for orthopedic surgeons. Tissue engineering is a promising method for repairing bone defects, and vascularization is critical to the performance of a tissue engineered bone. We report herein the construction of a vascularized tissue engineered bone with mesenchymal stem cells (MSCs) and MSC-derived endothelial cells (ECs) co-cultured in porous beta-tricalcium phosphate ceramic (beta-TCP) to repair 1.5-cm ulnar defects in the rabbit. Examination by X-ray and single photon emission computed tomography (SPECT), histologic analysis, and biomechanical tests were used to evaluate repair and the vascularization of the implants. The results showed that by co-seeding MSCs and MSC-derived ECs, the resulting vascularization was able to promote osteogenesis and improve mechanical properties. The rabbits treated with vascularized tissue engineered bone exhibited far more extensive osteogenesis and good vascularization. Therefore, we suggest that the vascularized tissue engineered bone constructed by co-culture of MSCs and MSC-derived ECs in porous beta-TCP may be an effective approach to promote repair of segmental bone defects and have potential for repairing large segmental bone defects in a clinical setting. PMID: 19880177 [PubMed - as supplied by publisher] |
| The cyclooxygenase-2-selective inhibitor, etodolac, but not aspirin reduces neovascularization in a murine ischemic hind limb model.
November 3, 2009 at 7:38 am
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| | The cyclooxygenase-2-selective inhibitor, etodolac, but not aspirin reduces neovascularization in a murine ischemic hind limb model. Eur J Pharmacol. 2009 Oct 29; Authors: Tanaka K, Yamamoto Y, Tsujimoto S, Uozumi N, Kita Y, Yoshida A, Shimizu T, Hisatome I Cyclooxygenase inhibitors are often prescribed to relieve severe ischemic leg pain in critical ischemic limb patients. Prescription of high doses of aspirin and selective cyclooxygenase-2 inhibitors is reported to increase cardiovascular events through suppression of the vaso-dilative prostanoid prostaglandin I(2) in endothelium. Here, we evaluated the influence of aspirin and etodolac, a selective cyclooxygenase-2 inhibitor, on neovascularization using a murine ischemia hind limb model. C57BL/6J mice were treated with aspirin or etodolac for twenty-eight days after induction of ischemia. We exploited a concentration of the agents that suppressed cyclooxygenase activity efficiently, especially in prostaglandin I(2) production. Recovery of limb blood perfusion and capillary density in ischemic limbs were significantly suppressed by etodolac treatment when compared to the aspirin treated group and untreated group. Production of 6-keto prostaglandin F(1alpha) and prostaglandin E(2) was lower in the aspirin treated group when compared with the etodolac treated group. Also, these concentrations were lower in both treatment groups compared with the untreated group. Immunohistochemical analysis suggested cyclooxygenase-2 was expressed in endothelium but not in inflammatory cells in ischemic tissue from the acute to chronic phase. Cyclooxygenase-1 was expressed strongly in inflammatory cells in the acute phase. Furthermore, bone-marrow-derived mononuclear cell transplantation improved neovascularization, whereas aspirin and etodolac did not inhibit these effects. Production of arachidonic acid metabolites by transplanted cells was independent of the improvement of neovascularization. In conclusion, cyclooxygenase-2 inhibition reduces ischemia-induced neovascularization. PMID: 19879866 [PubMed - as supplied by publisher] |
| Harvesting and cryopreservation of lymphatic endothelial cells for lymphatic tissue engineering.
November 3, 2009 at 7:38 am
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| | Harvesting and cryopreservation of lymphatic endothelial cells for lymphatic tissue engineering. Cryobiology. 2009 Oct 29; Authors: Jiang Z, Hu X, Kretlow JD, Liu N In order to provide a suitable source of cells for lymphatic tissue engineering, the present study was designed to investigate techniques for harvesting and cryopreservation of human dermal lymphatic endothelial cells (LECs) in vitro. The LECs were isolated from children's foreskins and then cultured in endothelial growth medium-2 MV (EGM-2-MV) with 5% FBS. The second passage LECs were suspended in cryopreservation solution containing 40% FBS and 10% Me2SO in EGM-2-MV, cooled to -80 degrees C at about 1 degrees C /min and stored in liquid nitrogen. Samples were thawed quickly in a 37 degrees C water bath, and the cryoprotectant was removed by serial elution. The membrane integrity of thawed LECs was determined by trypan blue staining exclusion, and their proliferation was evaluated using the MTT method. The expanded cells of two groups were identified using immunofluorescence staining and RT-PCR with lymphatic specific markers such as Podoplanin and VEGFR-3. Uptake of fluorescent DiI-Ac-LDL and microtubular formation in three-dimensional cultures were used to detect the function of LECs. Flow cytometry was applied to identify cells and to measure the apoptosis rate as well. Cryopreservation resulted in a retrieval of 67 +/- 4% and an intact cell rate of 80 +/- 3%. The early apoptosis rate of thawed LECs (9.15 +/- 0.34%) was higher than that of fresh control LECs (5.31 +/- 0.23%). The growth curves of thawed LECs were similar to those of fresh LECs. The thawed LECs were propagated for at least 6-7 passages without alterations in phenotype and function. Highly purified LECs can be isolated by immunomagnetic beads from human dermis. The cryopreserved/thawed and recultivated LECs are proven to have high vitality and growth potential in vitro and may be considered suitable seed cells for lymphatic tissue engineering. PMID: 19879864 [PubMed - as supplied by publisher] |
| Retinoic Acid from the meninges regulates cortical neuron generation.
November 3, 2009 at 7:38 am
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| | Retinoic Acid from the meninges regulates cortical neuron generation. Cell. 2009 Oct 30;139(3):597-609 Authors: Siegenthaler JA, Ashique AM, Zarbalis K, Patterson KP, Hecht JH, Kane MA, Folias AE, Choe Y, May SR, Kume T, Napoli JL, Peterson AS, Pleasure SJ Extrinsic signals controlling generation of neocortical neurons during embryonic life have been difficult to identify. In this study we demonstrate that the dorsal forebrain meninges communicate with the adjacent radial glial endfeet and influence cortical development. We took advantage of Foxc1 mutant mice with defects in forebrain meningeal formation. Foxc1 dosage and loss of meninges correlated with a dramatic reduction in both neuron and intermediate progenitor production and elongation of the neuroepithelium. Several types of experiments demonstrate that retinoic acid (RA) is the key component of this secreted activity. In addition, Rdh10- and Raldh2-expressing cells in the dorsal meninges were either reduced or absent in the Foxc1 mutants, and Rdh10 mutants had a cortical phenotype similar to the Foxc1 null mutants. Lastly, in utero RA treatment rescued the cortical phenotype in Foxc1 mutants. These results establish RA as a potent, meningeal-derived cue required for successful corticogenesis. PMID: 19879845 [PubMed - in process] |
| TNFalpha and TGF-beta1 influence IL-18-induced IFNgamma production through regulation of IL-18 receptor and T-bet expression.
November 3, 2009 at 7:38 am
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| | TNFalpha and TGF-beta1 influence IL-18-induced IFNgamma production through regulation of IL-18 receptor and T-bet expression. Cytokine. 2009 Oct 29; Authors: Koutoulaki A, Langley M, Sloan AJ, Aeschlimann D, Wei XQ Bacterial infections can lead to a state of uncontrolled inflammation and also trigger autoimmune disease. At the centre of this are CD4(+) T cell responses in inflammatory tissues or local lymph nodes which are orchestrated by dendritic cells. IL-18 is a pro-inflammatory cytokine that drives dendritic cell maturation and mediates IFNgamma production. In this study, we demonstrate that in the dendritic precursor-like cell line KG-1, IFNgamma production induced by IL-18 is potentiated (>5-fold) by TNFalpha and completely suppressed by TGF-beta1. IL-18 stimulation rapidly activates different MAPK signalling pathways but only blocking of p38 activation alleviates IFNgamma production. The mechanism through which TNFalpha enhances IL-18 induced IFNgamma production is by promoting IL-18 receptor alpha-chain expression which results in higher levels of p38 activation and induces expression of T-bet, a transcriptional regulator of the IFNG gene. In contrast, TGF-beta1 rapidly suppresses IFNgamma production by limiting IL-18 receptor numbers at the cell surface and preventing induction of T-bet expression. TGF-beta1 experience by cells leads to sustained long-term inactivation of TNFalpha/IL-18-mediated cell activation but not IL-18 induced p38 activation suggesting transcriptional silencing of the T-BET and/or IFNG promoter independent of MAPK signalling. These results demonstrate how IL-18 activity is regulated by pro and anti-inflammatory cytokines and thereby provide insight into the mechanism that controls dendritic cell activity and ultimately leads to resolution of an inflammatory response. PMID: 19879772 [PubMed - as supplied by publisher] |
| Induction of EPC homing on biofunctionalized vascular grafts for rapid in vivo self-endothelialization - A review of current strategies.
November 3, 2009 at 7:38 am
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| | Induction of EPC homing on biofunctionalized vascular grafts for rapid in vivo self-endothelialization - A review of current strategies. Biotechnol Adv. 2009 Oct 28; Authors: Avci-Adali M, Ziemer G, Wendel HP For years intensive research has been done to improve the hemocompatibility of blood contacting vascular devices. Despite the enormous progress in physicochemical surface optimization technologies, the native endothelium still represents the ideal surface for blood contact. Numerous tissue engineering strategies aspired towards the endothelialization of graft surfaces to generate a non-thrombogenic barrier on artificial materials. A paradigm change in surface modification concepts is the in vivo endothelialization of vascular grafts by capturing circulating endothelial progenitor cells (EPCs) directly from the blood stream via biofunctionalized implant materials. Thereby, capture molecules are immobilized on artificial vascular grafts to mimic a pro-homing substrate for EPCs. In this review, different coating strategies for in vivo capturing of EPCs on synthetic implants are discussed. This therapeutic concept opens a new chapter in regenerative medicine by realizing the vision that every patient seeds his implants with his own progenitor cells to make the synthetic grafts unrecognizable for the body's rejection mechanisms. PMID: 19879347 [PubMed - as supplied by publisher] |
| Dose-dependent Efficacy of ALS-human Mesenchymal Stem Cells Transplantation into Cisterna Magna in SOD1-G93A ALS mice.
November 3, 2009 at 7:38 am
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| | Dose-dependent Efficacy of ALS-human Mesenchymal Stem Cells Transplantation into Cisterna Magna in SOD1-G93A ALS mice. Neurosci Lett. 2009 Oct 28; Authors: Kim H, Kim HY, Choi MR, Hwang S, Nam KH, Kim HC, Han JS, Kim KS, Kim SH Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by motor neuron loss. Although the underlying cause of the disease remains unclear, a variety of pathogenic mechanisms have been proposed. Despite promising preclinical studies showing the modification of the disease progression, most trials have failed to demonstrate any significant improvement in outcome. Stem cell therapy therefore has been proposed as an alternative therapy for ALS. In this study, we evaluated the dose-dependent effects of human bone marrow mesenchymal stem cells (hMSCs) obtained from an ALS patient (ALS-hMSCs) on SOD1 mice via intrathecal injection and showed its practicality for hMSCs. We transplanted different doses (1x10(4), 2x10(5), and 1x10(6)) of ALS-hMSCs into the cisterna magna and performed clinical observations including symptom onset, survival time, and locomotor performance using the rotarod test. Nissl staining was performed to evaluate motor neurons in lumbar spinal cord sections at 109 days, and transplanted cells were evaluated by immuno-fluorescence staining at the end stage. A cell dose of 1x10(6) cells significantly prolonged life span and delayed the decline of motor performance. At this dose, the average number of motor neurons was significantly higher than those of the untreated and 1x10(4) cell treated groups. Most injected hMSCs distributed in the ventricular system and subarachnoid space, while some migrated into the brain and spinal cord. These data suggest that intrathecal injection with an optimized cell number could be a potential route for stem cell therapy in ALS patients. PMID: 19879334 [PubMed - as supplied by publisher] |
| Wide-spectrum profile of inflammatory mediators in the plasma and scales of patients with psoriatic disease.
November 3, 2009 at 7:38 am
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| | Wide-spectrum profile of inflammatory mediators in the plasma and scales of patients with psoriatic disease. Cytokine. 2009 Oct 28; Authors: Deeva I, Mariani S, De Luca C, Pacifico V, Leoni L, Raskovic D, Kharaeva Z, Korkina L, Pastore S Psoriasis is a chronic recurrent inflammatory disorder of the skin. Clinical subtypes include psoriasis vulgaris (PV), psoriatic arthropathy, and erythrodermic psoriasis. Aim of this study was to analyse relevant inflammatory mediators in the plasma of patients with distinct subtypes of active psoriasis, and in the scales of mild-to-moderate PV patients, and correlation to disease severity. Compared to healthy controls (n=10), patients affected by very severe forms of psoriasis (n=30) were characterized by increased plasma levels of IL-4, IL-6, MCP-1, VEGF and in particular PDGFbb. Each group with severe psoriasis had distinct characteristic features of plasma cytokine profile. Mild-to-moderate PV patients (n=35) showed higher levels of IL-4, IL-6, IL-10, and IL-13 when compared to healthy controls. No correlation was found between PV severity assessed by PASI (Psoriasis Area and Severity Index) and levels of these mediators. By contrast, disease severity correlated to scale levels of IP-10. For the first time, we found exaggerated circulating levels of the pro-angiogenic PDGFbb and VEGF in severe psoriasis. Evidence that the severity of skin symptoms correlated exclusively with scale levels of IP-10, but not with any up-regulated inflammatory mediator in plasma, suggests that distinct skin-independent processes contribute to the circulating cytokine profile in psoriasis. PMID: 19879157 [PubMed - as supplied by publisher] |
| Hydrodynamic spinning of hydrogel fibers.
November 3, 2009 at 7:38 am
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| | Hydrodynamic spinning of hydrogel fibers. Biomaterials. 2009 Oct 28; Authors: Hu M, Deng R, Schumacher KM, Kurisawa M, Ye H, Purnamawati K, Ying JY Hydrogel scaffolds are highly hydrated polymer networks that allow cells to adhere, proliferate and differentiate in the treatment of diseased or injured tissues and organs. Using hydrodynamic shaping and in situ cross-linking of hydrogel precursors, we have developed a highly efficient "hydrodynamic spinning" approach for synthesizing hydrogel fibers of different diameters in a multiphase coaxial flow. A triple-orifice spinneret has been created, and three different types of hydrogel precursors have been examined. Without changing the spinning head, hollow and solid hydrogel fibers with different diameters have been spun by simply manipulating the ratio of input flow rates. Together with the ability of simultaneous cell-seeding in the hydrogel matrix, hydrodynamic spinning can be broadly applied to many hydrogel materials, providing a powerful technique in the preparation of fiber-like and tubule-like hydrogel constructs for tissue engineering. PMID: 19878994 [PubMed - as supplied by publisher] |
| Utility of telomerase-pot1 fusion protein in vascular tissue engineering.
November 3, 2009 at 7:38 am
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| | Utility of telomerase-pot1 fusion protein in vascular tissue engineering. Cell Transplant. 2009 Oct 29; Authors: Petersen TH, Hitchcock T, Muto A, Calle EA, Zhao L, Gong Z, Gui L, Dardik A, Bowles DE, Counter CM, Niklason LE While advances in regenerative medicine and vascular tissue engineering have been substantial in recent years, important stumbling blocks remain. In particular, the limited lifespan of differentiated cells that are harvested from elderly human donors is an important limitation in many areas of regenerative medicine. Recently, a mutant of the human telomerase reverse transcriptase enzyme (TERT) was described, which is highly processive and elongates telomeres more rapidly than conventional telomerase. This mutant, called pot1-TERT, is a chimeric fusion between the DNA binding protein pot1 and TERT. Because pot1-TERT is highly processive, it is possible that transient delivery of this transgene to cells that are utilized in regenerative medicine applications may elongate telomeres and extend cellular lifespan while avoiding risks that are associated with retroviral or lentiviral vectors. In the present study, adenoviral delivery of pot1-TERT resulted in transient reconstitution of telomerase activity in human smooth muscle cells, as demonstrated by telomeric repeat amplification protocol (TRAP). In addition, human engineered vessels that were cultured using pot1-TERT expressing cells had greater collagen content and somewhat better performance in vivo than control grafts. Hence, transient delivery of pot1-TERT to elderly human cells may be useful for increasing cellular lifespan and improving the functional characteristics of resultant tissue engineered constructs. PMID: 19878625 [PubMed - as supplied by publisher] |
| The clonogenic potential of hematopoietic stem cells and mesenchymal stromal cells in various hematologic diseases: a pilot study.
November 3, 2009 at 7:38 am
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| | The clonogenic potential of hematopoietic stem cells and mesenchymal stromal cells in various hematologic diseases: a pilot study. Cytotherapy. 2009 Nov 2; Authors: Yüksel MK, Topçuoğlu P, Kurdal M, Ilhan O Abstract Background aims. Mesenchymal stromal cells (MSC) are the most popular cells used in regenerative medicine and biotechnology. The clonogenic potential of these cells is defined by colony-forming unit-fibroblasts (CFU-F). It is well known that there is an interaction between hematopoietic cells and stromal cells in disease formation pathogenesis. Therefore we hypothesized that there should be a quantitative and qualitative relationship between MSC colonies (CFU-F) and hematopoietic stem cell colonies (colony-forming unit-granulocyte-macrophages; CFU-GM) among patients with and without hematologic diseases. Methods. Forty-two patients were included in this study. Patients were divided into three groups: group A, patients with hematologic malignancies (n=20); group B, patients with bone marrow (BM) failure (n=11); group C, patients without hematologic diseases (n=11). BM aspirates were plated in different densities for CFU-F culture. The plating density was the same for CFU-GM culture. Results. CFU-GM colonies grew in 90% of group A cells and all of group B and C cells (P=0.0001). CFU-F colonies became visible on the ninth day of plating in group A and on the eight day in groups B and C. There was no statistically significant difference between the groups for the duration of CFU-F colony formation (P=0.12). There were differences in the morphology of the colonies among the groups. Conclusions. This is the first study that has compared the clonogenic potential of stromal cells and hematopoietic stem cells in the same subjects with and without hematologic diseases. No correlation was shown between the clonogenic potential of stromal cells and hematopoietic cells. PMID: 19878078 [PubMed - as supplied by publisher] |
| Efficient expansion of mesenchymal stromal cells from umbilical cord under low serum conditions.
November 3, 2009 at 7:38 am
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| | Efficient expansion of mesenchymal stromal cells from umbilical cord under low serum conditions. Cytotherapy. 2009;11(6):738-48 Authors: Girdlestone J, Limbani VA, Cutler AJ, Navarrete CV Background Mesenchymal stromal cells (MSC) are of clinical interest for their potential use in regenerative medicine and immunotherapy. Originally derived from bone marrow (BM), MSC have now been isolated from most tissues, including umbilical cord (UC) and UC blood (UCB). If MSC from UC are biologically equivalent to those from BM, they would be attractive as a readily available and non-invasive source for cellular therapies. Methods Sections of UC were separated into vascular and Wharton's jelly (WJ) fractions, which were then digested individually to release MSC that were isolated by plastic adherence in a 10% fetal calf serum (FCS) medium, or a low serum medium designed for multipotent adult progenitor cells (MAPC). The resulting perivascular (PV) and WJ MSC lines were assayed for expression of characteristic markers and differentiation and immunosuppressive properties. Results MSC lines were readily derived from most UC tested. Cells grown in MAPC medium (MM) tended to be smaller and more elongated and expressed more nestin, but did not differ substantially in their growth rate, expression of other markers and differentiation capacity. All UC lines tested were adipogenic but poorly osteogenic, and were equivalent in their ability to suppress T-cell proliferation induced by phytohemagglutinin (PHA), activation beads and allostimulation. Conclusions UC is a convenient, efficient source of MSC that can be expanded under low serum conditions for application on future studies of tissue regeneration and immunosuppression. PMID: 19878060 [PubMed - in process] |
| An alternative method for the isolation of mesenchymal stromal cells derived from lipoaspirate samples.
November 3, 2009 at 7:38 am
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| | An alternative method for the isolation of mesenchymal stromal cells derived from lipoaspirate samples. Cytotherapy. 2009;11(6):706-15 Authors: Baptista LS, do Amaral RJ, Carias RB, Aniceto M, Claudio-da-Silva C, Borojevic R Background aims Since initial methods were developed for isolating cells from adipose tissue, little has been done to improve mesenchymal stromal cell (MSC) yield. The aim of the present study was to isolate a population of MSC from lipoaspirate samples without tissue digestion and to assess the possibility of cryopreserving the freshly isolated cells. Methods A population of MSC was isolated from 13 patients' lipoaspirate samples by mechanical dissociation. Mechanically processed lipoaspi-rate adipose tissue (MPLA) cells were characterized after in vitro cell expansion by morphologic analysis, expression of MSC surface markers and differentiation assays. Results Mechanical dissociation yielded a large quantity of adherent MSC both after standard and vibro-assisted liposuction. Preservation of lipoaspirate samples at 4 degrees C for 1 or 2 days until the mechanical procedure did not change the MPLA cell content. It was possible to store freshly isolated MPLA cells by cryopreservation without loss of the MSC population. Adherent MPLA cells were negative for CD45 and CD31 and positive for CD34, CD105, CD44 and CD90. They also showed adipogenic, osteogenic and chondrogenic potentials similar to MSC populations from other sources as already described in the literature. Conclusions MSC can be isolated from human lipoaspirate samples by the mechanical procedure described in this study with a significant reduction in time and cost. Together with cryopreservation of freshly isolated MPLA cells, this has made it easier to harvest and store MSC for therapeutic applications such as soft-tissue augmentation and tissue engineering. PMID: 19878057 [PubMed - in process] |
| Airway regeneration: the role of the Clara cell secretory protein and the cells that express it.
November 3, 2009 at 7:38 am
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| | Airway regeneration: the role of the Clara cell secretory protein and the cells that express it. Cytotherapy. 2009;11(6):676-87 Authors: Wong AP, Keating A, Waddell TK Abstract Clara cell secretory protein (CCSP) is one of the most abundant proteins in the airway surface fluid, and has many putative functions. Recent advances in the field of stem cells and lung regeneration have identified potentially new roles of CCSP and CCSP-expressing cell populations in airway maintenance, repair and regeneration. This review focuses on the airway regenerative potential of CCSP and the cells that express this protein. The use of this protein or CCSP-expressing cells as an indication of biologic processes that contribute to lung injury or repair is highlighted. PMID: 19878054 [PubMed - in process] |
| Synergistic increase in osteosarcoma cell sensitivity to photodynamic therapy with aminolevulinic acid hexyl ester in the presence of hyperthermia.
November 3, 2009 at 7:38 am
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| | Synergistic increase in osteosarcoma cell sensitivity to photodynamic therapy with aminolevulinic acid hexyl ester in the presence of hyperthermia. Photomed Laser Surg. 2009 Oct;27(5):791-7 Authors: Yanase S, Nomura J, Matsumura Y, Watanabe Y, Tagawa T OBJECTIVE: We observed that two osteosarcoma cell lines from the same tumor displayed marked differences in their sensitivities to photodynamic therapy (PDT) with aminolevulinic acid hexyl ester (hALA-PDT). We investigated why these two closely related lines had different hALA-PDT sensitivities and whether the PDT phototoxicity of the less sensitive cell line could be increased by a simultaneous application of hyperthermia (HT). METHODS: Flow cytometry was used to evaluate the intracellular accumulation of protoporphyrin IX (PpIX), a metabolic product of aminolevulinic acid, in two human mandibular osteosarcoma cell lines (HOSM-1 and HOSM-2) treated with HT, hALA-PDT, or hALA-PDT combined with HT (PDT + HT). With hALA-PDT, cells treated with 0.2 mM hALA were irradiated with a light dose of 10-80 J/cm(2) from a near-infrared irradiator. With PDT + HT, the cells were treated as for hALA-PDT except that the temperature was raised to 43.5 degrees C during irradiation. RESULTS: At 6 h after hALA treatment, HOSM-2 cells carried about 1.53-fold more PpIX than HOSM-1 cells. With hALA-PDT, the survival rate for HOSM-1 cells treated with 80 J/cm(2) irradiation was 35.7%, while that for HOSM-2 cells treated with 40-80 J/cm(2) was below 12%. With PDT + HT, the survival rate for HOSM-1 and HOSM-2 cells treated with 80 J/cm(2) irradiation was 14.1% and 10.7%, respectively. CONCLUSION: A combination therapy comprising hALA-PDT + HT treatment may be very useful for the treatment of tumors containing cells that are insensitive to hALA-PDT, such as the HOSM-1 cell line described in this study. PMID: 19878029 [PubMed - in process] |
| Self-Assembly of Fibronectin Mimetic Peptide-Amphiphile Nanofibers.
November 3, 2009 at 7:38 am
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| | Self-Assembly of Fibronectin Mimetic Peptide-Amphiphile Nanofibers. Langmuir. 2009 Oct 30; Authors: Rexeisen EL, Fan W, Pangburn TO, Taribagil RR, Bates FS, Lodge TP, Tsapatsis M, Kokkoli E Single-tailed peptide-amphiphiles have been shown to form nanofibers in solution and gel after screening of their electrostatic charges, and those containing cell-binding motifs are promising as tissue engineering scaffolds. A fibronectin-mimetic peptide sequence was developed, containing both the primary binding domain RGD and the synergy binding domain PHSRN, which has shown superior cell adhesion properties over simple RGD sequences and fibronectin in 2D culture. In order to test this sequence in a 3D environment in the future, we have designed a C(16) single-tailed peptide-amphiphile, PR_g (with a peptide headgroup of GGGSSPHSRN(SG)(5)RGDSP), that forms nanofibers and a gel in solution without any screening of its positive charge. In this study, we characterized the self-assembly properties of the PR_g peptide-amphiphile via critical micelle concentration (CMC) measurements, circular dichroism (CD) spectroscopy, cryo-transmission electron microscopy (cryo-TEM), small angle neutron scattering (SANS), and rheology measurements. The CMC of the PR_g amphiphile was determined to be 38 muM. CD measurements showed that even though the peptide formed an unordered secondary structure, the peptide-amphiphile's spectrum after aging resembled more the spectrum of an alpha+beta protein. Cryo-TEM images of a 100 muM peptide-amphiphile solution showed individual nanofibers with a diameter of approximately 10 nm and lengths on the order of several micrometers. Images taken at higher concentrations (1 mM) show a high degree of bundling among the nanofibers, and at even higher concentrations (3 and 4 mM) SANS measurements also indicated that the peptide-amphiphile formed rod-shaped structures in solution. The peptide-amphiphile gel was monitored by parallel-plate rheometry, and the elastic modulus (G') was greater than the viscous modulus (G''), which indicates that PR_g forms a gel. The shear modulus for a 2 day old gel was measured to be approximately 500 Pa, which is within the modulus range for living tissue; thus, the PR_g gel shows potential as a possible scaffold for tissue engineering. PMID: 19877715 [PubMed - as supplied by publisher] |
| Teeth grown in mice.
November 3, 2009 at 7:38 am
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| | Teeth grown in mice. Br Dent J. 2009 Aug 22;207(4):147 Authors: PMID: 19696814 [PubMed - indexed for MEDLINE] |
| Mechanisms of resistance to interferon-gamma-mediated cell growth arrest in human oral squamous carcinoma cells.
November 3, 2009 at 7:38 am
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| | Mechanisms of resistance to interferon-gamma-mediated cell growth arrest in human oral squamous carcinoma cells. J Biol Chem. 2009 Sep 11;284(37):24869-80 Authors: Hiroi M, Mori K, Sekine K, Sakaeda Y, Shimada J, Ohmori Y Interferon-gamma (IFNgamma) has an antiproliferative effect on a variety of tumor cells. However, many tumor cells resist treatment with IFNs. Here, we show that IFNgamma fails to inhibit the growth of some types of oral squamous cell carcinoma (OSCC) cells that possess a fully functional IFNgamma/STAT1 (signal transducer and activator of transcription-1) signaling pathway. IFNgamma inhibited the growth of the HSC-2, HSC-3, and HSC-4 OSCC cell lines. However, Ca9-22 cells were resistant to IFNgamma despite having intact STAT1-dependent signaling, such as normal tyrosine phosphorylation, DNA binding activity, and transcriptional activity of STAT1. The growth inhibition of HSC-2 cells resulted from S-phase arrest of the cell cycle. IFNgamma inhibited cyclin A2 (CcnA2)-associated kinase activity, which correlated with the IFNgamma-mediated down-regulation of CcnA2 and Cdk2 expression at both the transcriptional and post-transcriptional level in HSC-2 cells but not in Ca9-22 cells. RNAi-mediated knockdown of CcnA2 and Cdk2 resulted in growth inhibition in both cell lines. These results indicate that the resistance of OSCC to IFNgamma is not due simply to the deficiency in STAT1-dependent signaling but results from a defect in the signaling component that mediates this IFNgamma-induced down-regulation of CcnA2 and Cdk2 expression at the transcriptional and post-transcriptional levels. PMID: 19596857 [PubMed - indexed for MEDLINE] |
| De novo synthesis of human dermis in vitro in the absence of a three-dimensional scaffold.
November 3, 2009 at 7:38 am
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| | De novo synthesis of human dermis in vitro in the absence of a three-dimensional scaffold. In Vitro Cell Dev Biol Anim. 2009 Sep;45(8):430-41 Authors: Pouyani T, Ronfard V, Scott PG, Dodd CM, Ahmed A, Gallo RL, Parenteau NL Neonatal human dermal fibroblasts cultured in vitro synthesize an organized and physically substantial three-dimensional extracellular matrix, without the addition of exogenous matrix components or synthetic scaffolds. De novo matrix synthesis proceeds in an orderly manner over a 21-d culture period and beyond. Analysis of the fibroblast phenotype, i.e., matrix synthesis by the fibroblasts, suggests that both serum and serum-free conditions are conducive to the production of a human tissue-engineered "dermal equivalent". We report that given the appropriate permissive environment, the fibroblasts establish and grow a tissue in vitro, which bears striking biochemical and physical resemblance to normal human dermis. PMID: 19533257 [PubMed - indexed for MEDLINE] |
| Polypyrrole-coated electrospun PLGA nanofibers for neural tissue applications.
November 3, 2009 at 7:38 am
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| | Polypyrrole-coated electrospun PLGA nanofibers for neural tissue applications. Biomaterials. 2009 Sep;30(26):4325-35 Authors: Lee JY, Bashur CA, Goldstein AS, Schmidt CE Electrospinning is a promising approach to create nanofiber structures that are capable of supporting adhesion and guiding extension of neurons for nerve regeneration. Concurrently, electrical stimulation of neurons in the absence of topographical features also has been shown to guide axonal extension. Therefore, the goal of this study was to form electrically conductive nanofiber structures and to examine the combined effect of nanofiber structures and electrical stimulation. Conductive meshes were produced by growing polypyrrole (PPy) on random and aligned electrospun poly(lactic-co-glycolic acid) (PLGA) nanofibers, as confirmed by scanning electron micrographs and X-ray photon spectroscopy. PPy-PLGA electrospun meshes supported the growth and differentiation of rat pheochromocytoma 12 (PC12) cells and hippocampal neurons comparable to non-coated PLGA control meshes, suggesting that PPy-PLGA may be suitable as conductive nanofibers for neuronal tissue scaffolds. Electrical stimulation studies showed that PC12 cells, stimulated with a potential of 10 mV/cm on PPy-PLGA scaffolds, exhibited 40-50% longer neurites and 40-90% more neurite formation compared to unstimulated cells on the same scaffolds. In addition, stimulation of the cells on aligned PPy-PLGA fibers resulted in longer neurites and more neurite-bearing cells than stimulation on random PPy-PLGA fibers, suggesting a combined effect of electrical stimulation and topographical guidance and the potential use of these scaffolds for neural tissue applications. PMID: 19501901 [PubMed - indexed for MEDLINE] |
| Crosstalk between osteoblasts and endothelial cells co-cultured on a polycaprolactone-starch scaffold and the in vitro development of vascularization.
November 3, 2009 at 7:38 am
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| | Crosstalk between osteoblasts and endothelial cells co-cultured on a polycaprolactone-starch scaffold and the in vitro development of vascularization. Biomaterials. 2009 Sep;30(26):4407-15 Authors: Santos MI, Unger RE, Sousa RA, Reis RL, Kirkpatrick CJ The reconstruction of bone defects based on cell-seeded constructs requires a functional microvasculature that meets the metabolic demands of the engineered tissue. Therefore, strategies that augment neovascularization need to be identified. We propose an in vitro strategy consisting of the simultaneous culture of osteoblasts and endothelial cells on a starch-based scaffold for the formation of pre-vascular structures, with the final aim of accelerating the establishment of a vascular bed in the implanted construct. Human dermal microvascular endothelial cells (HDMECs) were co-cultured with human osteoblasts (hOBs) on a 3D starch-based scaffold and after 21 days of culture HDMEC aligned and organized into microcapillary-like structures. These vascular-like structures evolved from a cord-like configuration to a more complex branched morphology, had a lumen and stained in the perivascular region for type IV collagen. Genetic profiling of 84 osteogenesis-related genes was performed on co-culture vs. monoculture. Osteoblasts in co-culture showed a significant up-regulation of type I collagen and immunohistochemistry revealed that the scaffold was filled with a dense matrix stained for type I collagen. In direct contact with HDMEC hOBs secreted higher amounts of VEGF in relation to monoculture and the highest peak in the release profile correlated with the formation of microcapillary-like structures. The heterotypic communication between the two cell types was also assured by direct cell-cell contact as shown by the expression of the gap junction connexin 43. In summary, by making use of heterotypic cellular crosstalk this co-culture system is a strategy to form vascular-like structures in vitro on a 3D scaffold. PMID: 19487022 [PubMed - indexed for MEDLINE] |
| Tissue-engineered polyethylene oxide/chitosan scaffolds as potential substitutes for articular cartilage.
November 3, 2009 at 7:38 am
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| | Tissue-engineered polyethylene oxide/chitosan scaffolds as potential substitutes for articular cartilage. J Biomed Mater Res A. 2009 Oct;91(1):277-87 Authors: Kuo YC, Hsu YR Applications of composite scaffolds comprising polyethylene oxide (PEO) and chitosan to the culture of bovine knee chondrocytes (BKC) were investigated. Here, PEO and chitosan with various weight ratios were crosslinked, refrigerated at -80 degrees C, and lyophilized. Pore surfaces of the PEO/chitosan scaffolds were chemically modified by human fibronectin for accelerating BKC adhesion and growth. The results revealed that the range of pore diameters was between 200 and 400 mum. A high content of PEO in scaffolds generated high porosity, moisture content, physical ductility, biodegradation rate, and BKC viability, as well as low Young's and compression moduli. High levels of PEO, human fibronectin, and extracellular calcium were favorable to the BKC culture, as indicated by the enhanced amounts of BKC, glycosaminoglycans, and collagen. However, a high concentration of medium potassium caused detrimental influences on the proliferation of BKC and the secretion of extracellular matrices. The present PEO/chitosan scaffolds showed enhancements in biomedical characteristics for the formation of tissue-engineered cartilage toward clinical prosthesis. PMID: 18980201 [PubMed - indexed for MEDLINE] |
| Increased osteoblast functions in the presence of BMP-7 short peptides for nanostructured biomaterial applications.
November 3, 2009 at 7:38 am
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| | Increased osteoblast functions in the presence of BMP-7 short peptides for nanostructured biomaterial applications. J Biomed Mater Res A. 2009 Oct;91(1):296-304 Authors: Chen Y, Webster TJ To improve bone regeneration around orthopedic biomaterials, researchers have attempted to combine growth factors on and in implants. Equally as exciting, greater bone growth has been demonstrated around nanoscaled materials (like helical rosette nanotubes or nanocrystalline hydroxyapatite) that mimic the geometry of the natural components of bone. To combine these two approaches, in this in vitro study, the ability of three short peptides [labeled for convenience: a or SNVILKKYRN, b or KPSSAPTQLN, and c or KAISVLYFDDS chosen from the larger bone morphogenetic protein-7 (BMP-7)] to promote osteoblast (bone-forming cells) functions were determined. Shorter peptides of BMP-7 are required for growth factor incorporation into nanoscale biomaterials because their sizes are in the nanometer regime. Results showed that of all the peptides, peptide b and the peptide combination a,b, enhanced osteoblast density the most after 5 days when compared with the controls (no growth factors). Furthermore, osteoblasts cultured with peptide b had a larger and more spread morphology than did controls. In addition, peptide c and its combinations (a, c; b, c; and a, b, c) increased osteoblast calcium deposition after 14 and 21 days compared with the controls. Since these peptides are much smaller than BMP-7, the results of this study provided information that peptides can be easily chemically functionalized onto nanoscaled biomaterials to improve bone growth. Thus, the present study elucidated that shorter peptides in BMP-7 was found to be more appropriate for inclusion in and on nanomaterials to promote osteoblast proliferation (peptide b and the peptide combination a,b) and osteoblast deposition of calcium-containing mineral (peptide c and the peptide combinations a,c; b,c; and a, b, c). PMID: 18980196 [PubMed - indexed for MEDLINE] |
| Promoting neurite outgrowth from spiral ganglion neuron explants using polypyrrole/BDNF-coated electrodes.
November 3, 2009 at 7:38 am
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| | Promoting neurite outgrowth from spiral ganglion neuron explants using polypyrrole/BDNF-coated electrodes. J Biomed Mater Res A. 2009 Oct;91(1):241-50 Authors: Evans AJ, Thompson BC, Wallace GG, Millard R, O'Leary SJ, Clark GM, Shepherd RK, Richardson RT Release of neurotrophin-3 (NT3) and brain-derived neurotrophic factor (BDNF) from hair cells in the cochlea is essential for the survival of spiral ganglion neurons (SGNs). Loss of hair cells associated with a sensorineural hearing loss therefore results in degeneration of SGNs, potentially reducing the performance of a cochlear implant. Exogenous replacement of either or both neurotrophins protects SGNs from degeneration after deafness. We previously incorporated NT3 into the conducting polymer polypyrrole (Ppy) synthesized with para-toluene sulfonate (pTS) to investigate whether Ppy/pTS/NT3-coated cochlear implant electrodes could provide both neurotrophic support and electrical stimulation for SGNs. Enhanced and controlled release of NT3 was achieved when Ppy/pTS/NT3-coated electrodes were subjected to electrical stimulation. Here we describe the release dynamics and biological properties of Ppy/pTS with incorporated BDNF. Release studies demonstrated slow passive diffusion of BDNF from Ppy/pTS/BDNF, with electrical stimulation significantly enhancing BDNF release over 7 days. A 3-day SGN explant assay found that neurite outgrowth from explants was 12.3-fold greater when polymers contained BDNF (p < 0.001), although electrical stimulation did not increase neurite outgrowth further. The versatility of Ppy to store and release neurotrophins, conduct electrical charge, and act as a substrate for nerve-electrode interactions is discussed for specialized applications such as cochlear implants. PMID: 18814235 [PubMed - indexed for MEDLINE] |
| Hexagonal micron scale pillars influence epithelial cell adhesion, morphology, proliferation, migration, and cytoskeletal arrangement.
November 3, 2009 at 7:38 am
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| | Hexagonal micron scale pillars influence epithelial cell adhesion, morphology, proliferation, migration, and cytoskeletal arrangement. J Biomed Mater Res A. 2009 Oct;91(1):149-57 Authors: Nematollahi M, Hamilton DW, Jaeger NJ, Brunette DM A desirable attribute of implants penetrating epithelium is the inhibition of downward epithelial migration. Simple grooved topographies can inhibit this migration either directly or indirectly by promoting connective tissue attachment, but few studies have focused on the direct effect of geometrically complex topographies on epithelial behavior. Therefore, we examined the influence of novel topographies comprising square floors surrounded by six-sided pillars on periodontal ligament epithelial cell adhesion, morphology, cytoskeletal organization, and migration. Relative to cells on smooth surface, epithelial cells on the pillar substrata adhered closely, exhibited reduced proliferation, had a reduced velocity, but higher persistence. Vinculin staining demonstrated that cells formed mature adhesions on the pillar tops, but smaller punctate adhesion in the gaps and on the pillar walls. Overall more mature adhesions were found on pillars compared to smooth surfaces, which may account for the reduced speed of migration limited on the pillars. F-actin stress fibers were predominantly found on pillar tops within 6 h, whereas microtubules (MTs) had a tendency to form in the gaps between the six-sided pillars. In conclusion, microfabricated pillars altered epithelial migration in ways that could prove useful in inhibition of epithelial downward migration on transmucosal implants. PMID: 18773428 [PubMed - indexed for MEDLINE] |
| Covalent surface modification of a titanium alloy with a phosphorylcholine-containing copolymer for reduced thrombogenicity in cardiovascular devices.
November 3, 2009 at 7:38 am
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| | Covalent surface modification of a titanium alloy with a phosphorylcholine-containing copolymer for reduced thrombogenicity in cardiovascular devices. J Biomed Mater Res A. 2009 Oct;91(1):18-28 Authors: Ye SH, Johnson CA, Woolley JR, Snyder TA, Gamble LJ, Wagner WR Our objective was to develop a surface modification strategy for a titanium alloy (TiAl6V4) to provide thromboresistance for surfaces in rigorous blood-contacting cardiovascular applications, such as that found in ventricular assist devices. We hypothesized that this could be accomplished by the covalent attachment of a phospholipid polymer, poly(2-methacryloyloxyethylphosphorylcholine (MPC)-co-methacryl acid) (PMA). TiAl6V4 was H2O plasma treated by radio frequency glow discharge, silanated with 3-aminopropyltriethoxysilane (APS), and ammonia plasma treated to increase surface reactivity. The TiAl6V4 surface was then modified with PMA via a condensation reaction between the amino groups on the TiAl6V4 surface and the carboxyl groups on PMA. The surface composition was verified by X-ray photoelectron spectroscopy, confirming successful modification of the TiAl6V4 surfaces with APS and PMA as evidenced by increased Si and P. Plasma treatments with H2O and ammonia were effective at further increasing the surface reactivity of TiAl6V4 as evidenced by increased surface PMA. The adsorption of ovine fibrinogen onto PMA-modified surfaces was reduced relative to unmodified surfaces, and in vitro ovine blood contact through a rocking test revealed marked reductions in platelet deposition and bulk phase platelet activation relative to unmodified TiAl6V4 and polystyrene controls. The results indicate that the PMA-modification scheme for TiAl6V4 surfaces offers a potential pathway to improve the thromboresistance of the blood-contacting surfaces of cardiovascular devices. PMID: 18683221 [PubMed - indexed for MEDLINE] |
| [The development of plastic surgery : Retrospective view of 80 years of "Der Chirurg" (The Surgeon).]
November 3, 2009 at 7:38 am
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| | [The development of plastic surgery : Retrospective view of 80 years of "Der Chirurg" (The Surgeon).] Chirurg. 2009 Nov 1; Authors: Horch RE The often groundbreaking developments of new methods in Plastic Surgery have been published in the journal "Der Chirurg" (The Surgeon) ever since its foundation in 1928, when it was established as a journal dealing with all aspects of surgery and containing many innovations and developments. Historically this is also reflected in the establishment of Plastic Surgery initially as a subspecialty and later on as a specialty within the German Society for Surgery. The interdisciplinary character of modern reconstructive and oncological concepts, not only with other specialties but also within various surgical specialties, raises further challenges and leads to new developments in reconstruction, which will definitely induce an increasing amount of knowledge to the advantage of our patients. Scientific and clinical advances over the last 80 years give rise to the hope that similar success will be attained for reconstruction of traumatic and oncological defects and malformations or disfigurations in the future. Consolidated findings from regenerative medicine and tissue engineering will enrich the daily practice of surgical reconstruction. PMID: 19882333 [PubMed - as supplied by publisher] |
| Developments in injectable multiphasic biomaterials. The performance of microporous biphasic calcium phosphate granules and hydrogels.
November 3, 2009 at 7:38 am
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| | Developments in injectable multiphasic biomaterials. The performance of microporous biphasic calcium phosphate granules and hydrogels. J Mater Sci Mater Med. 2009 Nov 1; Authors: Daculsi G, Uzel AP, Weiss P, Goyenvalle E, Aguado E Calcium phosphate bioceramic granules associated with hydrosoluble polymers were developed as bone substitutes for various maxillofacial and orthopaedic applications. These injectable bone substitutes, support and regenerate bone tissue and resorb after implantation. The efficiency of these multiphasic materials is due to the osteogenic and osteoconductive properties of the microporous biphasic calcium phosphate. The associated hydrosoluble polymers are considered as carriers in order to achieve the rheological properties of injectable bone substitutes (IBS). In this study, we used 2 semi synthetic hydrosoluble polymers of polysaccharidic origin. The hydroxy propyl methyl cellulose (HPMC), with and without silane, was combined with microporous BCP granules. The presence of silane induced considerable gelation of the suspension. The 2 IBS used (without gelation, IBS1, with gelation, IBS2) were implanted in critical size femoral epiphysis defects in rabbits. No foreign body reactions were observed in either sample. However, because of the higher density from gelation, cell colonisation followed by bone tissue ingrowth was delayed over time with IBS2 compared to the IBS1 without gelation. The results showed resorption of the BCP granule and bone ingrowth at the expense of both IBS with different kinetics. This study demonstrates that the hydrogel cannot be considered merely as a carrier. The gelation process delayed cell and tissue colonisation by slow degradation of the HPMC Si, compared to the faster release of HPMC with IBS1, in turn inducing faster permeability and spaces for tissue ingrowth between the BCP granules. PMID: 19882306 [PubMed - as supplied by publisher] |
| Isolation, characterization and osteogenic differentiation of adipose-derived stem cells: from small to large animal models.
November 3, 2009 at 7:38 am
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| | Isolation, characterization and osteogenic differentiation of adipose-derived stem cells: from small to large animal models. Cell Tissue Res. 2009 Oct 31; Authors: Arrigoni E, Lopa S, de Girolamo L, Stanco D, Brini AT One of the most important issues in orthopaedic surgery is the loss of bone resulting from trauma, infections, tumours or congenital deficiency. In view of the hypothetical future application of mesenchymal stem cells isolated from human adipose tissue in regenerative medicine, we have analysed and characterized adipose-derived stem cells (ASCs) isolated from adipose tissue of rat, rabbit and pig. We have compared their in vitro osteogenic differentiation abilities for exploitation in the repair of critical osteochondral defects in autologous pre-clinical models. The number of pluripotent cells per millilitre of adipose tissue is variable and the yield of rabbit ASCs is lower than that in rat and pig. However, all ASCs populations show both a stable doubling time during culture and a marked clonogenic ability. After exposure to osteogenic stimuli, ASCs from rat, rabbit and pig exhibit a significant increase in the expression of osteogenic markers such as alkaline phosphatase, extracellular calcium deposition, osteocalcin and osteonectin. However, differences have been observed depending on the animal species and/or differentiation period. Rabbit and porcine ASCs have been differentiated on granules of clinical grade hydroxyapatite (HA) towards osteoblast-like cells. These cells grow and adhere to the scaffold, with no inhibitory effect of HA during osteo-differentiation. Such in vitro studies are necessary in order to select suitable pre-clinical models to validate the use of autologous ASCs, alone or in association with proper biomaterials, for the repair of critical bone defects. PMID: 19882172 [PubMed - as supplied by publisher] |
| Preparation of pooled human platelet lysate (pHPL) as an efficient supplement for animal serum-free human stem cell cultures.
November 3, 2009 at 7:38 am
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| | Preparation of pooled human platelet lysate (pHPL) as an efficient supplement for animal serum-free human stem cell cultures. J Vis Exp. 2009;(32): Authors: Schallmoser K, Strunk D Platelet derived growth factors have been shown to stimulate cell proliferation efficiently in vivo(1,2) and in vitro. This effect has been reported for mesenchymal stromal cells (MSCs), fibroblasts and endothelial colony-forming cells with platelets activated by thrombin(3-5) or lysed by freeze/thaw cycles(6-14) before the platelet releasate is added to the cell culture medium. The trophic effect of platelet derived growth factors has already been tested in several trials for tissue engineering and regenerative therapy.(1,15-17) Varying efficiency is considered to be at least in part due to individually divergent concentrations of growth factors(18,19) and a current lack of standardized protocols for platelet preparation.(15,16) This protocol presents a practicable procedure to generate a pool of human platelet lysate (pHPL) derived from routinely produced platelet rich plasma (PRP) of forty to fifty single blood donations. By several freeze/thaw cycles the platelet membranes are damaged and growth factors are efficiently released into the plasma. Finally, the platelet fragments are removed by centrifugation to avoid extensive aggregate formation and deplete potential antigens. The implementation of pHPL into standard culture protocols represents a promising tool for further development of cell therapeutics propagated in an animal protein-free system. PMID: 19881465 [PubMed - in process] |
| Legal and ethical aspects of organ donation and transplantation.
November 3, 2009 at 7:38 am
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| | Legal and ethical aspects of organ donation and transplantation. Indian J Urol. 2009 Jul;25(3):348-55 Authors: Shroff S The legislation called the Transplantation of Human Organ Act (THO) was passed in India in 1994 to streamline organ donation and transplantation activities. Broadly, the act accepted brain death as a form of death and made the sale of organs a punishable offence. With the acceptance of brain death, it became possible to not only undertake kidney transplantations but also start other solid organ transplants like liver, heart, lungs, and pancreas. Despite the THO legislation, organ commerce and kidney scandals are regularly reported in the Indian media. In most instances, the implementation of the law has been flawed and more often than once its provisions have been abused. Parallel to the living related and unrelated donation program, the deceased donation program has slowly evolved in a few states. In approximately one-third of all liver transplants, the organs have come from the deceased donor program as have all the hearts and pancreas transplants. In these states, a few hospitals along with committed NGOs have kept the momentum of the deceased donor program. The MOHAN Foundation (NGO based in Tamil Nadu and Andhra Pradesh) has facilitated 400 of the 1,300 deceased organ transplants performed in the country over the last 14 years. To overcome organ shortage, developed countries are re-looking at the ethics of unrelated programs and there seems to be a move towards making this an acceptable legal alternative. The supply of deceased donors in these countries has peaked and there has been no further increase over the last few years. India is currently having a deceased donation rate of 0.05 to 0.08 per million population. We need to find a solution on how we can utilize the potentially large pool of trauma-related brain deaths for organ donation. This year in the state of Tamil Nadu, the Government has passed seven special orders. These orders are expected to streamline the activity of deceased donors and help increase their numbers. Recently, on July 30, 2008, the Government brought in a few new amendments as a Gazette with the purpose of putting a stop to organ commerce. The ethics of commerce in organ donation and transplant tourism has been widely criticized by international bodies. The legal and ethical principles that we follow universally with organ donation and transplantation are also important for the future as these may be used to resolve our conflicts related to emerging sciences such as cloning, tissue engineering, and stem cells. PMID: 19881131 [PubMed - in process] |
| [Progress of Research for Osteoarthritis. Tissue engineering therapy for osteoarthritis.]
November 3, 2009 at 7:38 am
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| | [Progress of Research for Osteoarthritis. Tissue engineering therapy for osteoarthritis.] Clin Calcium. 2009 Nov;19(11):1621-8 Authors: Hattori K, Ohgushi H To repair articular cartilage defects, transplantation of various tissue or cells have been investigated. In 1994, autologous chondrocyte implantation was introduced by Brittberg et al. and the technology has been widely applied to repair cartilage defects caused by trauma. However, it is hard to be applied for articular cartilage defects in osteoarthritic patients. Recently, several researchers are trying to treat osteoarthritis using tissue-engineering approaches on the basis of stem cells and scaffold. In this paper, we introduce the trend of the approaches for cartilage defects and refer to the possibility for the treatments of osteoarthritic patients. PMID: 19880995 [PubMed - in process] | | | 
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