| Human DAZL, DAZ and BOULE genes modulate primordial germ-cell and haploid gamete formation.
October 30, 2009 at 6:59 am
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| | Human DAZL, DAZ and BOULE genes modulate primordial germ-cell and haploid gamete formation. Nature. 2009 Oct 28; Authors: Kee K, Angeles VT, Flores M, Nguyen HN, Reijo Pera RA The leading cause of infertility in men and women is quantitative and qualitative defects in human germ-cell (oocyte and sperm) development. Yet, it has not been possible to examine the unique developmental genetics of human germ-cell formation and differentiation owing to inaccessibility of germ cells during fetal development. Although several studies have shown that germ cells can be differentiated from mouse and human embryonic stem cells, human germ cells differentiated in these studies generally did not develop beyond the earliest stages. Here we used a germ-cell reporter to quantify and isolate primordial germ cells derived from both male and female human embryonic stem cells. By silencing and overexpressing genes that encode germ-cell-specific cytoplasmic RNA-binding proteins (not transcription factors), we modulated human germ-cell formation and developmental progression. We observed that human DAZL (deleted in azoospermia-like) functions in primordial germ-cell formation, whereas closely related genes DAZ and BOULE (also called BOLL) promote later stages of meiosis and development of haploid gametes. These results are significant to the generation of gametes for future basic science and potential clinical applications. PMID: 19865085 [PubMed - as supplied by publisher] |
| Regenerative medicine: Advances in new methods and technologies.
October 30, 2009 at 6:59 am
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| | Regenerative medicine: Advances in new methods and technologies. Med Sci Monit. 2009 Nov;15(11):RA233-251 Authors: Park DH, Eve DJ The articles published in the journal Cell Transplantation - The Regenerative Medicine Journal over the last two years reveal the recent and future cutting-edge research in the fields of regenerative and transplantation medicine. 437 articles were published from 2007 to 2008, a 17% increase compared to the 373 articles in 2006-2007. Neuroscience was still the most common section in both the number of articles and the percentage of all manuscripts published. The increasing interest and rapid advance in bioengineering technology is highlighted by tissue engineering and bioartificial organs being ranked second again. For a similar reason, the methods and new technologies section increased significantly compared to the last period. Articles focusing on the transplantation of stem cell lineages encompassed almost 20% of all articles published. By contrast, the non-stem cell transplantation group which is made up primarily of islet cells, followed by biomaterials and fetal neural tissue, etc. comprised less than 15%. Transplantation of cells pre-treated with medicine or gene transfection to prolong graft survival or promote differentiation into the needed phenotype, was prevalent in the transplantation articles regardless of the kind of cells used. Meanwhile, the majority of non-transplantation-based articles were related to new devices for various purposes, characterization of unknown cells, medicines, cell preparation and/or optimization for transplantation (e.g. isolation and culture), and disease pathology.<br /> PMID: 19865067 [PubMed - in process] |
| Bone tissue engineering therapeutics: controlled drug delivery in three-dimensional scaffolds.
October 30, 2009 at 6:59 am
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| | Bone tissue engineering therapeutics: controlled drug delivery in three-dimensional scaffolds. J R Soc Interface. 2009 Oct 28; Authors: Mouriño V, Boccaccini AR This paper provides an extensive overview of published studies on the development and applications of three-dimensional bone tissue engineering (TE) scaffolds with potential capability for the controlled delivery of therapeutic drugs. Typical drugs considered include gentamicin and other antibiotics generally used to combat osteomyelitis, as well as anti-inflammatory drugs and bisphosphonates, but delivery of growth factors is not covered in this review. In each case reviewed, special attention has been given to the technology used for controlling the release of the loaded drugs. The possibility of designing multifunctional three-dimensional bone TE scaffolds for the emerging field of bone TE therapeutics is discussed. A detailed summary of drugs included in three-dimensional scaffolds and the several approaches developed to combine bioceramics with various polymeric biomaterials in composites for drug-delivery systems is included. The main results presented in the literature are discussed and the remaining challenges in the field are summarized with suggestions for future research directions. PMID: 19864265 [PubMed - as supplied by publisher] |
| Direct contribution of axial impact compressive load to anterior tibial load during simulated ski landing impact.
October 30, 2009 at 6:59 am
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| | Direct contribution of axial impact compressive load to anterior tibial load during simulated ski landing impact. J Biomech. 2009 Oct 26; Authors: Yeow CH, Lee PV, Goh JC Anterior tibial loading is a major factor involved in the anterior cruciate ligament (ACL) injury mechanism during ski impact landing. We sought to investigate the direct contribution of axial impact compressive load to anterior tibial load during simulated ski landing impact of intact knee joints without quadriceps activation. Twelve porcine knee specimens were procured. Four specimens were used as non-impact control while the remaining eight were mounted onto a material-testing system at 70 degrees flexion and subjected to simulated landing impact, which was successively repeated with incremental actuator displacement. Four specimens from the impacted group underwent pre-impact MRI for tibial plateau angle measurements while the other four were subjected to histology and microCT for cartilage morphology and volume assessment. The tibial plateau angles ranged from 29.4 to 38.8 degrees . There was a moderate linear relationship (Y=0.16X; R(2)=0.64; p<0.001) between peak axial impact compressive load (Y) and peak anterior tibial load (X). The anterior and posterior regions in the impacted group sustained surface cartilage fraying, superficial clefts and tidemark disruption, compared to the control group. MicroCT scans displayed visible cartilage deformation for both anterior and posterior regions in the impacted group. Due to the tibial plateau angle, increased axial impact compressive load can directly elevate anterior tibial load and hence contribute to ACL failure during simulated landing impact. Axial impact compressive load resulted in shear cartilage damage along anterior-posterior tibial plateau regions, due to its contribution to anterior tibial loading. This mechanism plays an important role in elevating ACL stress and cartilage deformation during impact landing. PMID: 19863961 [PubMed - as supplied by publisher] |
| Peyronie's Surgery: Graft Choices and Outcomes.
October 30, 2009 at 6:59 am
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| | Peyronie's Surgery: Graft Choices and Outcomes. Curr Urol Rep. 2009 Nov;10(6):460-7 Authors: Lentz AC, Carson Iii CC Peyronie's disease (PD), a localized fibrosis of the tunica albuginea surrounding the penile corpora, results in penile curvature and sexual dysfunction. Men with significant penile curvature and satisfactory erectile function are often treated with plaque incision or excision and grafting. The advantages and disadvantages of various grafting materials have long been debated. Graft materials can be divided into three categories: autologous tissue harvested from the patient's body, allograft or xenograft from another person or species, and synthetic grafts. Despite groundbreaking advances in physiology, synthetic materials, and tissue engineering, the ideal graft material has yet to be established. This review presents and discusses the variety of graft materials available for the surgical correction of PD. For this purpose, a MEDLINE search was conducted on PD until May 2009. PMID: 19863858 [PubMed - in process] |
| Histochemical analyses of tissue-engineered human menisci.
October 30, 2009 at 6:59 am
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| | Histochemical analyses of tissue-engineered human menisci. Connect Tissue Res. 2009;50(5):307-14 Authors: Schoenfeld AJ, Jacquet R, Lowder E, Doherty A, Leeson MC, Landis WJ The field of tissue engineering remains one of the least explored areas of current meniscal research but holds great promise. In this investigation, meniscal fibrochondrocytes were isolated from fresh human meniscal tissue and seeded onto synthetic polyglycolic acid (PGA) scaffolds. Constructs were implanted into the dorsal subcutaneous space of athymic nude mice. Control scaffolds, devoid of meniscal cells, were simultaneously implanted in additional mice. Constructs were harvested over 12 weeks and treated with a variety of histochemical stains to analyze general specimen morphology, cellular viability and proliferation, and collagen secretion. Results indicate that meniscal fibrochondrocyte proliferation increased over the time of implantation with cellular consolidation occurring as the PGA scaffolding was progressively hydrolyzed. Collagen production also increased over time. There were favorable similarities between constructs and human meniscal controls in terms of cellular morphology, phenotypic expression, and collagen production. These initial findings demonstrate procedures supporting proliferation of meniscal fibrochondrocytes, expression of fibrochondral phenotype, and the formation of putative meniscal tissue. PMID: 19863389 [PubMed - in process] |
| The evaluation of a biphasic osteochondral implant coupled with an electrospun membrane in a large animal model.
October 30, 2009 at 6:59 am
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| | The evaluation of a biphasic osteochondral implant coupled with an electrospun membrane in a large animal model. Tissue Eng Part A. 2009 Oct 28; Authors: Ho ST, Hutmacher DW, Ekaputra AK, Hitendra D, James HH Conventional clinical therapies are unable to resolve osteochondral defects adequately, hence tissue engineering solutions are sought to address the challenge. A biphasic implant which was seeded with Mesenchymal Stem Cells (MSC) and coupled with an electrospun membrane was evaluated as an alternative. This dual phase construct comprised of a Polycaprolactone (PCL) cartilage scaffold and a Polycaprolactone - Tri Calcium Phosphate (PCL - TCP) osseous matrix. Autologous MSC was seeded into the entire implant via fibrin and the construct was inserted into critically sized osteochondral defects located at the medial condyle and patellar groove of pigs. The defect was resurfaced with a PCL - collagen electrospun mesh that served as a substitute for periosteal flap in preventing cell leakage. Controls either without implanted MSC or resurfacing membrane were included. After 6 months, cartilaginous repair was observed with a low occurrence of fibrocartilage at the medial condyle. Osteochondral repair was promoted and host cartilage degeneration was arrested as shown by the superior Glycosaminoglycan (GAG) maintenance. This positive morphological outcome was supported by a higher relative Young's modulus which indicated functional cartilage restoration. Bone in growth and remodeling occurred in all groups with a higher degree of mineralization in the experimental group. Tissue repair was compromised in the absence of the implanted cells or the resurfacing membrane. Moreover healing was inferior at the patellar groove as compared to the medial condyle and this was attributed to the native biomechanical features. PMID: 19863255 [PubMed - as supplied by publisher] |
| Reduction of Neu5GC Xenoantigen on Human ADSC/MSCs lead to Them as Safer and More Useful Cell Sources for Realizing Various Stem Cell Therapies.
October 30, 2009 at 6:59 am
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| | Reduction of Neu5GC Xenoantigen on Human ADSC/MSCs lead to Them as Safer and More Useful Cell Sources for Realizing Various Stem Cell Therapies. Tissue Eng Part A. 2009 Oct 28; Authors: Komoda H, Okura H, Lee CM, Sougawa N, Iwayama T, Hashikawa T, Saga A, Yamamoto A, Ichinose A, Murakami S, Sawa Y, Matsuyama A Adipose tissue is an attractive source for somatic stem cell therapy. Currently, human ADSC/MSCs are usually cultured with fetal bovine serum (FBS). Recently, however, not only human embryonic stem cell lines cultured on mouse feeder cells but also bone marrow derived hMSCs cultured with FBS were reported to express N-glycolylneuraminic acid (Neu5Gc) xenoantigen. Human serum contains high titers of natural preformed antibodies against Neu5Gc. We studied the presence of Neu5Gc on hADSC/MSCs cultured with FBS and human immune response mediated by Neu5Gc. Our data indicated that hADSC/MSCs cultured with FBS expressed Neu5Gc and human natural preformed antibodies could bind to hADSC/MSCs. However, hADSC/MSCs express complement regulatory proteins such as CD46, CD55, and CD59 and is largely resistant to complement-mediated cytotoxity (CMC). hADSC/MSCs cultured with FBS could be injured by antibody dependent cell-mediated cytotoxicity (ADCC) mechanism. Furthermore, human monocyte derived macrophages could phagocytose hADSC/MSCs cultured with FBS and this phagocytosis activity increased in the presence of human serum. Culturing the hADSC/MSCs with heat-inactivated human serum for a week could markedly reduce Neu5Gc on hADSC/MSCs and prevented immune responses mediated by Neu5Gc, such as human natural preformed antibodies binding, ADCC, and phagocytosis. Adipogenic and osteogenic differentiation potential of hADSC/MSCs cultured with heat-inactivated human serum was not less than those cultured with FBS. For stem cell therapies based on hADSC/MSCs to be realized, hADSC/MSCs that presented Neu5Gc on their cell surfaces after exposure to FBS should be clean up to be rescued from xenogenic rejection. PMID: 19863253 [PubMed - as supplied by publisher] |
| Skin and bones (and cartilage): the dermal fibroblast connection.
October 30, 2009 at 6:59 am
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| | Skin and bones (and cartilage): the dermal fibroblast connection. Nat Rev Rheumatol. 2009 Sep;5(9):471-2 Authors: Tuan RS PMID: 19710666 [PubMed - indexed for MEDLINE] |
| The ideal graft of the future: a prospect of messianic proportions?
October 30, 2009 at 6:59 am
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| | The ideal graft of the future: a prospect of messianic proportions? Asian Cardiovasc Thorac Ann. 2009 Jun;17(3):238-9 Authors: Klima U, Kofidis T PMID: 19643845 [PubMed - indexed for MEDLINE] |
| Vitreous cryopreservation of tissue engineered bone composed of bone marrow mesenchymal stem cells and partially demineralized bone matrix.
October 30, 2009 at 6:59 am
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| | Vitreous cryopreservation of tissue engineered bone composed of bone marrow mesenchymal stem cells and partially demineralized bone matrix. Cryobiology. 2009 Oct;59(2):180-7 Authors: Yin H, Cui L, Liu G, Cen L, Cao Y Cryopreservation of tissue engineered products by maintaining their structure and function is a prerequisite for large-scale clinical applications. In this study, we examined the feasibility of cryopreservation of tissue engineered bone (TEB) composed of osteo-induced canine bone marrow mesenchymal stem cells (cBMSCs) and partially demineralized bone matrix (pDBM) scaffold by vitrification. A novel vitreous solution named as VS442 containing 40% dimethyl-sulfoxide (DMSO), 40% EuroCollins (EC) solution and 20% basic culture medium (BCM) was developed. After being cultured in vitro for 8 days, cell/scaffold complex in VS442 was subjected to vitreous preservation for 7 days and 3 months, respectively. Cell viability, proliferation and osteogenic differentiation of cBMSCs in TEB after vitreous cryopreservation were examined with parallel comparisons being made with those cryopreserved in VS55 vitreous solution. Compared with that cryopreserved in VS55, cell viability and subsequent proliferative ability of TEB in VS442 after being rewarmed were significantly higher as detected by live/dead staining and DNA assay. The level of alkaline phosphatase (ALP) expression and osteocalcin (OCN) deposition in VS442 preserved TEB was also higher than those in the VS55 group since 3days post-rewarm. Both cell viability and osteogenic capability of the VS55 group were found to be declined to a negligible level within 15 days post-rewarm. Furthermore, it was observed that extending the preservation of TEB in VS442 to 3 months did not render any significant effect on its survival and osteogenic potential. Thus, the newly developed VS442 vitreous solution was demonstrated to be more efficient in maintaining cellular viability and osteogenic function for vitreous cryopreservation of TEB over VS55. PMID: 19576196 [PubMed - indexed for MEDLINE] |
| Ex vivo functional evaluation of isolated strips in BAMG tissue-engineered bladders.
October 30, 2009 at 6:59 am
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| | Ex vivo functional evaluation of isolated strips in BAMG tissue-engineered bladders. Int J Artif Organs. 2009 Mar;32(3):159-65 Authors: Chen BS, Zhang SL, Geng H, Pan J, Chen F Although gastrointestinal segments have been widely used for bladder augmentation, they are still not considered ideal sources due to the possibility of complications. In this study, with the aim of reducing complications, we performed bladder augmentation in pigs using bladder acellular matrix grafts (BAMG) as a scaffold. Three months after surgery, the BAMG tissue-engineered bladders revealed bladder reconstruction that morphologically resembled that of the normal bladder. Functional experiments were performed to evaluate the contractile characteristics of isolated strips from both normal and BAMG tissue-engineered bladders 3 months after augmentation. No significant differences between these two groups were found in spontaneous contraction and contraction after electric stimulation; in the relaxing effect of epinephrine on potassium chloride-induced twitch height; in the contracting effects of acetylcholin; or in the antagonistic effect of atropine on acetylcholine-induced contraction. These results demonstrate that not only can BAMG tissue-engineered bladders be histologically reconstructed, they also possess electrophysiological and pharmacological characteristics similar to normal bladders. This further confirms BAMG as an ideal scaffold for bladder augmentation. PMID: 19440991 [PubMed - indexed for MEDLINE] |
| [Use of allogenic acellular dermal matrix combined with autologous epidermal cells for the repair of tissue defect]
October 30, 2009 at 6:59 am
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| | [Use of allogenic acellular dermal matrix combined with autologous epidermal cells for the repair of tissue defect] Zhonghua Kou Qiang Yi Xue Za Zhi. 2005 Sep;40(5):412-5 Authors: Zuo JH, Li JR, Li WX, Yang YC, Wu SH, Lü ZH OBJECTIVE: To investigate a method for the repair of tissue defect. METHODS: Allogenic acellular dermal matrixes (ADM) were implanted to full-thickness skin defects made on the dorsa of rats. Two weeks later, autologous suspended epidermal cells were transplanted on to the surface of vascularized ADM. Respectively, neoepidermis was macroscopically observed 2, 3, 5 weeks after grafting, and samples were taken to make routine paraffin sections for microscopical examination, and immunohistochemical staining for type IV collagen was also performed. RESULTS: The vascularized ADM could support proliferation and differentiation of epidermal cells, and also could promote the formation of dermal-epidermal junction. Suspended epidermal cells in an artificial culture system in vivo could develop into mature epidermis. The reconstructed skin not only looked like the normal one in appearance in which hair was removed, but also revealed a better function. CONCLUSIONS: Full-thickness skin defect can be repaired by transplanting autologous epidermal cell suspension on to vascularized ADM. PMID: 16255932 [PubMed - indexed for MEDLINE] |
| [Experimental study of tissue engineered bone loaded with osteointergrated dental implants]
October 30, 2009 at 6:59 am
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| | [Experimental study of tissue engineered bone loaded with osteointergrated dental implants] Zhonghua Kou Qiang Yi Xue Za Zhi. 2005 Jul;40(4):323-6 Authors: Fu SJ, Wang YX, Chen FL, Tao K, Zhang XD, Ge C OBJECTIVE: To investigate osteogenesis and integration of osteointergrated dental implants with marrow stromal osteoblast and cancellous bone matrix compound artificial bone (MCCAB) when embedded subcutaneously. METHODS: Osteointergrated dental implants (3 mm in diameter) were inserted into cancellous bone matrix (CBM) columns (5 mm in diameter). Marrow stromal osteoblast (MSO) were cultured and expanded in the column and on the surface. The osteointergrated dental implants loaded MSO-Alginate-CBM compound was formatted. This compound was then implanted subcutaneously in nude mice, and the osteointergrated dental implants loaded Alginate-CBM compounds were implanted as control. The compound was in the mice for 4 to 8 weeks and then harvested and assessed by means of gross observation, X-ray examination, histologic observation and computerized histomorphometry for evaluation of bone formation. RESULTS: The osteogenesis of the osteointergrated dental implants loaded MSO-Alginate-CBM compound was better than that of the the osteointergrated dental implants loaded Alginate-CBM compound. Both intramembranous and cartilaginous osteogenesis was seen but the former was predominant. A large amount of new bone formed around the implant and integrated well with the implant. In the control, only slight cartilage osteogenesis was seen and no integration was found. CONCLUSIONS: The results suggest that the new bone forms in the scaffolds and on the surface of the implant, and integration between the implant and artificial bone also occurs when they are implanted in the nude mice. PMID: 16191379 [PubMed - indexed for MEDLINE] | | | 
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