|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | We asked Paul Knoepfler, a UC Davis stem cell scientist, if he would care to comment additionally on our item Monday concerning the critical remarks about stem cell research, particularly in California, by Nicholas Wade of the New York Times.
Knoepfler had sharply criticized the article in a piece on his blog, which we differed with on Monday.
Here is what Knoepfler sent along to the | | | | | | | | | | | | | | | | | | | | | | | | | Electrospun Nanofibrous Polycaprolactone Scaffolds for Tissue Engineering of Annulus Fibrosus. Macromol Biosci. 2010 Nov 15; Authors: Koepsell L, Zhang L, Neufeld D, Fong H, Deng Y The annulus fibrosus comprises concentric lamellae that can be damaged due to intervertebral disc degeneration; to provide permanent repair of these acquired structural defects, one solution is to fabricate scaffolds that are designed to support the growth of annulus fibrosus cells. In this study, electrospun nanofibrous scaffolds of polycaprolactone are fabricated in random, aligned, and round-end configurations. Primary porcine annulus fibrosus cells are grown on the scaffolds and evaluated for attachment, proliferation, and production of extracellular matrix. The scaffold consisting of round-end nanofibers substantially outperforms the random and aligned scaffolds on cell adhesion; additionally, the scaffold with aligned nanofibers strongly affects the orientation of cells. PMID: 21080441 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Biofabrication of a three-dimensional liver micro-organ as an in vitro drug metabolism model. Biofabrication. 2010 Nov 15;2(4):045004 Authors: Chang R, Emami K, Wu H, Sun W In their normal in vivo matrix milieu, tissues assume complex well-organized three-dimensional architectures. Therefore, the primary aim in the tissue engineering design process is to fabricate an optimal analog of the in vivo scenario. This challenge can be addressed by applying emerging layered biofabrication approaches in which the precise configuration and composition of cells and bioactive matrix components can recapitulate the well-defined three-dimensional biomimetic microenvironments that promote cell-cell and cell-matrix interactions. Furthermore, the advent of and refinements in microfabricated systems can present physical and chemical cues to cells in a controllable and reproducible fashion unmatched with conventional cultures, resulting in the precise construction of engineered biomimetic microenvironments on the cellular length scale in geometries that are readily parallelized for high throughput in vitro models. As such, the convergence of layered solid freeform fabrication (SFF) technologies along with microfabrication techniques enables the creation of a three-dimensional micro-organ device to serve as an in vitro platform for cell culture, drug screening or to elicit further biological insights, particularly for NASA's interest in a flight-suitable high-fidelity microscale platform to study drug metabolism in space and planetary environments. The proposed model in this paper involves the combinatorial setup of an automated syringe-based, layered direct cell writing bioprinting process with micro-patterning techniques to fabricate a microscale in vitro device housing a chamber of bioprinted three-dimensional liver cell-encapsulated hydrogel-based tissue constructs in defined design patterns that biomimic the cell's natural microenvironment for enhanced biological functionality. In order to assess the structural formability and biological feasibility of such a micro-organ, reproducibly fabricated tissue constructs were biologically characterized for liver cell-specific function. Another key facet of the in vivo microenvironment that was recapitulated with the in vitro system included the necessary dynamic perfusion of the three-dimensional microscale liver analog with cells probed for their collective drug metabolic function and suitability as a drug metabolism model. This paper details the principles and methods that undergird the direct cell writing biofabrication process development and adaptation of microfluidic devices for the creation of a drug screening model, thereby establishing a novel drug metabolism study platform for NASA's interest to adopt a microfluidic microanalytical device with an embedded three-dimensional microscale liver tissue analog to assess drug pharmacokinetic profiles in planetary environments. PMID: 21079286 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | A novel route for the production of chitosan/poly(lactide-co-glycolide) graft copolymers for electrospinning. Biomed Mater. 2010 Nov 15;5(6):065016 Authors: Xie D, Huang H, Blackwood K, Macneil S Both chitosan and polylactide/polyglycolide have good biocompatibility and can be used to produce tissue engineering scaffolds for cultured cells. However the synthetic scaffolds lack groups that would facilitate their modification, whereas chitosan has extensive active amide and hydroxyl groups which would allow it to be subsequently modified for the attachment of peptides, proteins and drugs. Also chitosan is very hydrophilic, whereas PLGA is relatively hydrophobic. Accordingly there are many situations where it would be ideal to have a copolymer of both, especially one that could be electrospun to provide a versatile range of scaffolds for tissue engineering. Our aim was to develop a novel route of chitosan-g-PLGA preparation and evaluate the copolymers in terms of their chemical characterization, their performance on electrospinning and their ability to support the culture of fibroblasts as an initial biological evaluation of these scaffolds. Chitosan was first modified with trimethylsilyl chloride, and catalyzed by dimethylamino pyridine. PLGA-grafted chitosan copolymers were prepared by reaction with end-carboxyl PLGA (PLGA-COOH). FT-IR and(1)H-NMR characterized the copolymer molecular structure as being substantially different to that of the chitosan or PLGA on their own. Elemental analysis showed an average 18 pyranose unit intervals when PLGA-COOH was grafted into the chitosan molecular chain. Differential scanning calorimetry results showed that the copolymers had different thermal properties from PLGA and chitosan respectively. Contact angle measurements demonstrated that copolymers became more hydrophilic than PLGA. The chitosan-g-PLGA copolymers were electrospun to produce either nano- or microfibers as desired. A 3D fibrous scaffold of the copolymers gave good fibroblast adhesion and proliferation which did not differ significantly from the performance of the cells on the chitosan or PLGA electrospun scaffolds. In summary this work presents a methodology for making a hybrid material of natural and synthetic polymers which can be electrospun and reacts well as a substrate for cell culture. PMID: 21079284 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Polycaprolactone diacrylate crosslinked biodegradable semi-interpenetrating networks of polyacrylamide and gelatin for controlled drug delivery. Biomed Mater. 2010 Nov 15;5(6):065014 Authors: Jaiswal M, Dinda AK, Gupta A, Koul V A biodegradable semi-interpenetrating hydrogel network (semi-IPN) of polyacrylamide and gelatin was prepared using polycaprolactone diacrylate (mol. wt ∼ 640) as a crosslinker. The drug-polymer interaction and IPN formation were investigated by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and thermal gravimetric analysis (TGA). Scanning electron micrographs of lyophilized matrices revealed porous internal structure with varying pore sizes under equilibrium hydrated conditions, depending upon formulation composition. pH-dependent swelling and degradation was enhanced with increasing gelatin content and decreasing crosslinker concentration (Cs). Compression modulus (CM) (at 20% strain) increased significantly from 23 ± 1.4 to 75 ± 2.7 kPa (p < 0.02) with increasing Cs (from 0.5 to 2.0 mol%), while it decreased from 162 ± 6.4 to 23 ± 1.4 kPa (p < 0.05) with decreasing PAm/G ratio. Cell viability studies by MTT assay showed excellent cytocompatibility of matrices with fibroblast L929 cells. Curcumin, a hydrophobic phytochemical, was loaded by a diffusion method and its release profile was investigated in 4% w/v aqueous BSA solution at 75 rpm (at 37 ± 0.2 °C). Fitting of drug release data in the Korsmeyer-Peppas model suggested sustained release behavior up to 10 days with a combination of diffusion and erosion mechanism (0.5 < n < 1.0; M(t)/M(∞) ≤ 0.6). The newly developed porous, biodegradable and elastic semi-IPNs may serve as an ideal matrix for controlled drug release and wound healing applications. The possibilities can be explored for pharmaceutical and tissue engineering applications. PMID: 21079283 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | In vitro corrosion, cytotoxicity and hemocompatibility of bulk nanocrystalline pure iron. Biomed Mater. 2010 Nov 15;5(6):065015 Authors: Nie FL, Zheng YF, Wei SC, Hu C, Yang G Bulk nanocrystalline pure iron rods were fabricated by the equal channel angular pressure (ECAP) technique up to eight passes. The microstructure and grain size distribution, natural immersion and electrochemical corrosion in simulated body fluid, cellular responses and hemocompatibility were investigated in this study. The results indicate that nanocrystalline pure iron after severe plastic deformation (SPD) would sustain durable span duration and exhibit much stronger corrosion resistance than that of the microcrystalline pure iron. The interaction of different cell lines reveals that the nanocrystalline pure iron stimulates better proliferation of fibroblast cells and preferable promotion of endothelialization, while inhibits effectively the viability of vascular smooth muscle cells (VSMCs). The burst of red cells and adhesion of the platelets were also substantially suppressed on contact with the nanocrystalline pure iron in blood circulation. A clear size-dependent behavior from the grain nature deduced by the gradual refinement microstructures was given and well-behaved in vitro biocompatibility of nanocrystalline pure iron was concluded. PMID: 21079282 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Human adipose tissue-derived mesenchymal stem cells facilitate the immunosuppressive effect of Cyclosporin A on T lymphocytes through Jagged-1 mediated inhibition of NF-κB signaling. Exp Hematol. 2010 Nov 12; Authors: Shi D, Liao L, Zhang B, Liu R, Dou X, Li J, Zhu X, Yu L, Chen D, Zhao RC OBJECTIVE: Cyclosporine A (CsA), known as an effective immunosuppressive agent, is widely used in clinical fields. Mesenchymal stem cells (MSCs) may exert immunomodulatory effects on immune system, but exact mechanisms underlying remains controversial. Here we investigated whether human adipose tissue-derived mesenchymal stem cells (AMSCs) facilitate in vitro the immunomodulatory effects of CsA and expored molecule mechanisms that may be involved. METHODS: Proliferation of T lymphocytes was measured by uptake of (3)H-thymidine. Transcription and production of interleukin-2 (IL-2) and interferon-γ (IFN-γ) were evaluated by real-time quantitative PCR, RT-PCR and ELISA. Nuclear factor κB (NF-κB) was assayed by Western blotting and EMSA. Expression of Jagged-1, Jagged-2 and Delta-1 of AMSCs were surveyed by flow cytometric analysis and Western blotting. RESULTS: Combination of moderate-dose AMSCs and low-dose CsA was significantly more powerful than moderate-dose AMSCs or large-dose CsA alone in suppressing transcription and production of IL-2 and IFN-γ, activation of NF-κB and proliferation of T lymphocytes. In addition, AMSCs expressed high level of Jagged-1 which induced activation of Notch signaling in T lymphocytes, thus reduced NF-κB activity.Anti-Jagged-1 neutralizing antibody and N [N-(3, 5-difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester (DAPT) could reverse this trend. CONCLUSION: Human AMSCs facilitate the immunosuppressive effect of CsA on T lymphocytes through Jagged-1/ Notch related inhibition of NF-κB signaling. The combination of AMSCs and CsA represents a rationale therapeutic approach aim to prevent adverse effects of CsA while maintaining its adequate immunosuppressive effect. The expression of Jagged-1 on AMSCs may provide an effective mechanism to the immunomodulatory activity of AMSCs via direct cell-cell interaction. PMID: 21078360 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Stem-cell "hype" in tracheal transplantation? Transplantation. 2010 Oct 27;90(8):927-8; author reply 928-9 Authors: Delaere P PMID: 20962608 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | The use of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) scaffolds for tarsal repair in eyelid reconstruction in the rat. Biomaterials. 2010 Oct;31(29):7512-8 Authors: Zhou J, Peng SW, Wang YY, Zheng SB, Wang Y, Chen GQ Tarsal repair is an important part for eyelid reconstruction. Presently traditional clinic treatments do not produce satisfactory repair effects. The key is to find a proper tarsal repair material. Microbial poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) was studied for application as tarsal substitute in this study. PHBHHx scaffolds were implanted into tarsal defects of Sprague-Dawley rats. Eyelid samples of implanted materials and blank defect controls were collected for histological examination at weekly intervals post surgery. Results were compared among PHBHHx scaffolds, commercial acellular dermal matrices (ADM) and blank defect controls. Both PHBHHx scaffolds and ADM provided satisfactory repair results compared with the blank controls even though the implanted PHBHHx scaffolds showed a 2 weeks inflammation. Fibrous encapsulation and scaffold degradation were observed for the PHBHHx implants. Combined with its strong, elastic mechanical properties, the tissue compatible and biodegradable PHBHHx was proven to be a suitable candidate for tarsal repair. PMID: 20663550 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Cellular shellization: surface engineering gives cells an exterior. Bioessays. 2010 Aug;32(8):698-708 Authors: Wang B, Liu P, Tang R Unlike eggs and diatoms, most single cells in nature do not have structured shells to provide extensive protection. It is a challenge to artificially confer shell structures on living cells to improve their inherent properties and functions. We discuss four different types of cellular shellizations: man-made hydrogels, sol-gels, polyelectrolytes, and mineral shells. We also explore potential applications, such as cell storage, protection, delivery, and therapy. We suggest that shellization could provide another means to regulate and functionalize cells. Specifically, the integration of living cells and non-living functional shells may be developed as a novel strategy to create "super" or intelligent cells. Unlike biological approaches, this material-based bio-interface regulation is inexpensive, effective, and convenient, opening up a novel avenue for cell-based technologies and practices. PMID: 20658708 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Functional skeletal muscle formation with a biologic scaffold. Biomaterials. 2010 Oct;31(29):7475-84 Authors: Valentin JE, Turner NJ, Gilbert TW, Badylak SF Biologic scaffolds composed of extracellular matrix (ECM) have been used to reinforce or replace damaged or missing musculotendinous tissues in both preclinical studies and in human clinical applications. However, most studies have focused upon morphologic endpoints and few studies have assessed the in-situ functionality of newly formed tissue; especially new skeletal muscle tissue. The objective of the present study was to determine both the in-situ tetanic contractile response and histomorphologic characteristics of skeletal muscle tissue reconstructed using one of four test articles in a rodent abdominal wall model: 1) porcine small intestinal submucosa (SIS)-ECM; 2) carbodiimide-crosslinked porcine SIS-ECM; 3) autologous tissue; or 4) polypropylene mesh. Six months after surgery, the remodeled SIS-ECM showed almost complete replacement by islands and sheets of skeletal muscle, which generated a similar maximal contractile force to native tissue but with greater resistance to fatigue. The autologous tissue graft was replaced by a mixture of collagenous connective tissue, adipose tissue with fewer islands of skeletal muscle compared to SIS-ECM and a similar fatigue resistance to native muscle. Carbodiimide-crosslinked SIS-ECM and polypropylene mesh were characterized by a chronic inflammatory response and produced little or no measurable tetanic force. The findings of this study show that non-crosslinked xenogeneic SIS scaffolds and autologous tissue are associated with the restoration of functional skeletal muscle with histomorphologic characteristics that resemble native muscle. PMID: 20638716 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Heparin-releasing scaffold for stem cells: a differentiating device for vascular aims. Regen Med. 2010 Jul;5(4):645-57 Authors: Spadaccio C, Rainer A, Centola M, Trombetta M, Chello M, Lusini M, Covino E, Toyoda Y, Genovese JA AIMS: Current limitations of tissue-engineered vascular grafts include timing for the scaffold preparation, cell type, cell differentiation and growth inside the construct, and thrombogenicity of the final device. To surmount these shortcomings, we developed a heparin-releasing poly-L-lactide (PLLA) scaffold using the electrospinning technique, to guide the differentiation of human mesenchymal stem cells towards the endothelial phenotype and to deliver a useful drug in the management of the postimplantation period. MATERIALS & METHODS: The heparin-releasing PLLA scaffold was produced by means of the electrospinning technique in a tubular shape. The scaffold was seeded with human mesenchymal stem cells and cultured for up to 1 week. Cell viability and cytotoxicity assays were performed, and cell differentiation was evaluated by immunofluorescence with confocal microscopy, cytofluorometry and western blotting. Heparin release was assayed by Azure A method and biological effectiveness of the drug was assessed by activated clotting time measurements. RESULTS: The scaffold exhibited a morphology favorable to cell attachment. Heparin release showed an initial burst within the first 24 h, followed by a further sustained release profile. After 48 h of culturing, the construct demonstrated adequate engraftment and viability. Increased proliferation compared with the control scaffold in bare PLLA, suggested the induction of a favorable microenvironment. A shift towards CD31 positivity and modifications in cell morphology were observed in the heparin-releasing PLLA scaffold. CONCLUSION: By exploiting the biological effects of heparin, we developed an ad hoc differentiating device towards the endothelial phenotype for autologous stem cell seeding and, at the same time, we were able to facilitate and optimize the management of the construct once in clinical settings. PMID: 20632865 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Regulatory considerations for the development of autologous induced pluripotent stem cell therapies. Regen Med. 2010 Jul;5(4):569-79 Authors: Carpenter MK, Couture LA Induced pluripotent stem (iPS) cells offer tremendous opportunity for the creation of autologous cellular therapies, in which gene correction or the avoidance of immune response issues are desirable. In addition, iPS cells avoid the ethical concerns raised by the sourcing of human embryonic stem cells (hESCs) from embryos. iPS cells share many characteristics with hESCs and it is anticipated that existing experience with hESCs will translate to rapid progress in moving iPS cell-derived products toward clinical trials. While the potential clinical value for these products is considerable, the nature of current manufacturing paradigms for autologous iPS cell products raises considerable regulatory concerns. Here, the regulatory challenges posed by autologous iPS cell-derived products are examined. We conclude that there will be considerable regulatory concerns primarily relating to reproducibility of the manufacturing process and safety testing within clinically limited time constraints. Demonstrating safety of the final cell product in an autologous setting will be the single greatest obstacle to progressing autologous iPS cell-based therapies into the clinic. PMID: 20632860 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Translational prospects for human induced pluripotent stem cells. Regen Med. 2010 Jul;5(4):509-19 Authors: Csete M The pace of research on human induced pluripotent stem (iPS) cells is frantic worldwide, based on the enormous therapeutic potential of patient-specific pluripotent cells free of the ethical and political issues that plagued human embryonic stem cell research. iPS cells are now relatively easy to isolate from somatic cells and reprogramming can be accomplished using nonmutagenic technologies. Access to iPS cells is already paying dividends in the form of new disease-in-a-dish models for drug discovery and as scalable sources of cells for toxicology. For translation of cell therapies, the major advantage of iPS cells is that they are autologous, but for many reasons, perfect immunologic tolerance of iPS-based grafts should not be assumed. This article focuses on the functional identity of iPS cells, anticipated safety and technical issues in their application, as well as a survey of the progress likely to be realized in clinical applications in the next decade. PMID: 20632855 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | News & views in ... Regenerative medicine. Regen Med. 2010 Jul;5(4):497-9 Authors: PMID: 20632852 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Induced pluripotent stem cells: opportunities and challenges. Regen Med. 2010 Jul;5(4):483-4 Authors: Lensch MW, Rao M PMID: 20632848 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Stem/progenitor cells from inflamed human dental pulp retain tissue regeneration potential. Regen Med. 2010 Jul;5(4):617-31 Authors: Alongi DJ, Yamaza T, Song Y, Fouad AF, Romberg EE, Shi S, Tuan RS, Huang GT BACKGROUND: Potent stem/progenitor cells have been isolated from normal human dental pulps termed dental pulp stem cells (DPSCs). However, it is unknown whether these cells exist in inflamed pulps (IPs). AIMS: To determine whether DPSCs can be identified and isolated from IPs; and if they can be successfully cultured, whether they retain tissue regeneration potential in vivo. MATERIALS & METHODS: DPSCs from freshly collected normal pulps (NPs) and IPs were characterized in vitro and their tissue regeneration potential tested using an in vivo study model. RESULTS: The immunohistochemical analysis showed that IPs expressed higher levels of mesenchymal stem cell markers STRO-1, CD90, CD105 and CD146 compared with NPs (p < 0.05). Flow cytometry analysis showed that DPSCs from both NPs and IPs expressed moderate to high levels of CD146, stage-specific embryonic antigen-4, CD73 and CD166. Total population doubling of DPSCs-IPs (44.6 + or - 2.9) was lower than that of DPSCs-NPs (58.9 + or - 2.5) (p < 0.05), and DPSCs-IPs appeared to have a decreased osteo/dentinogenic potential compared with DPSCs-NPs based on the mineral deposition in cultures. Nonetheless, DPSCs-IPs formed pulp/dentin complexes similar to DPSCs-NPs when transplanted into immunocompromised mice. CONCLUSION: DPSCs-IPs can be isolated and their mesenchymal stem cell marker profiles are similar to those from NPs. Although some stem cell properties of DPSCs-IPs were altered, cells from some samples remained potent in tissue regeneration in vivo. PMID: 20465527 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Effects of adenoviral-mediated coexpression of bone morphogenetic protein-7 and insulin-like growth factor-1 on human periodontal ligament cells. J Periodontal Res. 2010 Aug;45(4):532-40 Authors: Yang L, Zhang Y, Dong R, Peng L, Liu X, Wang Y, Cheng X BACKGROUND AND OBJECTIVE: Bone morphogenetic protein-7 (BMP-7) and insulin-like growth factor-1 (IGF-1) are important in periodontal reconstruction. However, their synergistic effect in periodontal regeneration by gene delivery has not been reported. In this study, gene delivery of these two growth factors to human periodontal ligament cells (hPDLCs) was examined for its effects on cell proliferation and differentiation. MATERIAL AND METHODS: Recombinant adenoviruses containing both human BMP-7 and IGF-1 cDNA created by introducing the internal ribosome entry site (IRES) sequence were used to transfer the genes into hPDLCs. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and cell cycle analysis were used to observe their effects on cell proliferation, while alkaline phosphatase activity measurement, RT-PCR and in vivo tests were conducted to investigate their effects on cell differentiation. RESULTS: The proliferation of hPDLCs transduced by adenoviruses coexpressing BMP-7 and IGF-1 was suppressed while their differentiation ability was enhanced. There was a synergism of BMP-7 and IGF-1 in up-regulating alkaline phosphatase activity and mRNA levels of collagen type I and Runx2. Implantation in vivo with scaffolds illustrated that the transduced cells exhibited osteogenic differentiation and formed bone-like structures. CONCLUSION: The combined delivery of BMP-7 and IGF-1 genes using an IRES-based strategy synergistically enhanced differentiation of hPDLCs. It is suggested that this could be a new potential method in gene therapy for periodontal reconstruction. PMID: 20412417 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | PDGF-BB protects cardiomyocytes from apoptosis and improves contractile function of engineered heart tissue. J Mol Cell Cardiol. 2010 Jun;48(6):1316-23 Authors: Vantler M, Karikkineth BC, Naito H, Tiburcy M, Didié M, Nose M, Rosenkranz S, Zimmermann WH Platelet-derived-growth-factor-BB (PDGF-BB) can protect various cell types from apoptotic cell death, and induce hypertrophic growth and proliferation, but little is known about its direct or indirect effects on cardiomyocytes. Cardiac muscle engineering is compromised by a particularly high rate of cardiomyocyte death. Here we hypothesized that PDGF-BB stimulation can (1) protect cardiomyocytes from apoptosis, (2) enhance myocyte content in and (3) consequently optimize contractile performance of engineered heart tissue (EHT). We investigated the effects of PDGF-receptor activation in neonatal rat heart monolayer- and EHT-cultures by isometric contraction experiments, cytomorphometry, (3)H-thymidine and (3)H-phenylalanine incorporation assays, quantitative PCR (calsequestrin 2, alpha-cardiac and skeletal actin, atrial natriuretic factor, alpha- and beta-myosin heavy chain), immunoblotting (activated caspase 3, Akt-phosphorylation), and ELISA (cell death detection). PDGF-BB did not induce hypertrophy or proliferation in cardiomyocytes, but enhanced contractile performance of EHT. This effect was concentration-dependent (E(max) 10 ng/ml) and maximal only after transient PDGF-BB stimulation (culture days 0-7; total culture duration: 12 days). Improvement of contractile function was associated with higher cardiomyocyte content, as a consequence of PDGF-BB mediated protection from apoptosis (lower caspase-3 activity particularly in cardiomyocytes in PDGF-BB treated vs. untreated EHTs). We confirmed the anti-apoptotic effect of PDGF-BB in monolayer cultures and observed that PI3-kinase inhibition with LY294002 attenuated PDGF-BB-mediated cardiomyocyte protection. We conclude that PDGF-BB does not induce hypertrophy or proliferation, but confers an anti-apoptotic effect on cardiomyocytes. Our findings suggest a further exploitation of PDGF-BB in cardiomyocyte protection in vivo and in vitro. PMID: 20307544 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Implantation increases tensile strength and collagen content of self-assembled tendon constructs. J Appl Physiol. 2010 Apr;108(4):875-81 Authors: Calve S, Lytle IF, Grosh K, Brown DL, Arruda EM Tissue-engineered tendons, derived from an autologous cell source, have the potential to provide an ideal replacement graft that is biologically compatible and has the ability to adapt to the specific mechanical requirements of the in vivo environment. Scaffold-free tendon constructs have been successfully engineered in vitro. However, when compared against native tendons the constructs demonstrate both a lower tensile strength and collagen content. We hypothesized that the in vitro environment lacks certain environmental stimuli and that implantation in vivo would facilitate the maturation of engineered tissues. Using primary Achilles tendon fibroblasts from adult rats, self-organizing constructs were created in vitro. Tendon constructs were implanted subcutaneously into the groins of adult rats for 4 wk, while controls remained in vitro. Implanted constructs increased in stiffness by three orders of magnitude when compared with the in vitro controls (7,500 vs. 22.3 kPa). This increase in tangent modulus correlated with a significant increase in collagen content, as measured by hydroxyproline concentration, from 3.9% for the in vitro controls to 22.7% in the in vivo conditioned group. In addition, collagen fiber diameter increased from 22.0 to 75.4 nm as a result of in vivo implantation. The tensile strength and collagen content of in vivo conditioned constructs were similar to the values determined for neonatal rat tibialis anterior tendons. PMID: 20110546 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Osteointegration of soft tissue grafts within the bone tunnels in anterior cruciate ligament reconstruction can be enhanced. Knee Surg Sports Traumatol Arthrosc. 2010 Aug;18(8):1038-51 Authors: Kuang GM, Yau WP, Lu WW, Chiu KY Anterior cruciate ligament reconstruction with a soft tissue autograft (hamstring autograft) has grown in popularity in the last 10 years. However, the issues of a relatively long healing time and an inferior histological healing result in terms of Sharpey-like fibers connection in soft tissue grafts are still unsolved. To obtain a promising outcome in the long run, prompt osteointegration of the tendon graft within the bone tunnel is essential. In recent decades, numerous methods have been reported to enhance osteointegration of soft tissue graft in the bone tunnel. In this article, we review the current literature in this research area, mainly focusing on strategies applied to the local bone tunnel environment. Biological strategies such as stem cell and gene transfer technology, as well as the local application of specific growth factors have been reported to yield exciting results. The use of biological bone substitute and physical stimulation also obtained promising results. Artificially engineered tissue has promise as a solution to the problem of donor site morbidity. Despite these encouraging results, the current available evidence is still experimental. Further clinical studies in terms of randomized control trial in the future should be conducted to extrapolate these basic science study findings into clinical practice. PMID: 19779894 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | Regenerative Medicine , November 2010, Vol. 5, No. 6, Pages 839-842.
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| | | | | | | | | | | | | | | | | | | | | | | | Regenerative Medicine , November 2010, Vol. 5, No. 6, Pages 987-987.
| | | | | | | | | | | | | | | | | | | | | | | | | The Role of PET with 13N-Ammonia and 18F-FDG in the Assessment of Myocardial Perfusion and Metabolism in Patients with Recent AMI and Intracoronary Stem Cell Injection. J Nucl Med. 2010 Nov 15; Authors: Castellani M, Colombo A, Giordano R, Pusineri E, Canzi C, Longari V, Piccaluga E, Palatresi S, Dellavedova L, Soligo D, Rebulla P, Gerundini P Over the last decade, the effects of stem cell therapy on cardiac repair after acute myocardial infarction (AMI) have been investigated with different imaging techniques. We evaluated a new imaging approach using (13)N-ammonia and (18)F-FDG PET for a combined analysis of cardiac perfusion, metabolism, and function in patients treated with intracoronary injection of endothelial progenitors or with conventional therapy for AMI. METHODS: A total of 15 patients were randomly assigned to 3 groups based on different treatments (group A: bone marrow-derived stem cells; group B: peripheral blood-derived stem cells; group C: standard therapy alone). The number of scarred and viable segments, along with the infarct size and the extent of the viable area, were determined on a 9-segment (13)N-ammonia/(18)F-FDG PET polar map. Myocardial blood flow (MBF) was calculated for each segment on the ammonia polar map, whereas a global evaluation of left ventricular function was obtained by estimating left ventricular ejection fraction (LVEF) and end-diastolic volume, both derived from electrocardiography-gated (18)F-FDG images. Both intragroup and intergroup comparative analyses of the mean values of each parameter were performed at baseline and 3, 6, and 12 mo after AMI. During follow-up, major cardiac events were also registered. RESULTS: A significant decrease (P < 0.05) in the number of scarred segments and infarct size was observed in group A, along with an increase in MBF (P < 0.05) and a mild improvement in cardiac function. Lack of infarct size shrinkage in group B was associated with a marked impairment of MBF (P = 0.01) and cardiac dysfunction. Ambiguous changes in infarct size, MBF, and LVEF were found in group C. No differences in number of viable segments or in extent of viable area were found among the groups. At clinical follow-up, no major cardiac events occurred in group A patients, whereas 2 patients of group B experienced in-stent occlusion and one patient of group C received a transplant for heart failure. CONCLUSION: Our data suggest that a single nuclear imaging technique accurately analyzes changes in myocardial perfusion and metabolism occurring after stem cell transplantation. PMID: 21078804 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Preventing cardiac remodeling: The combination of cell-based therapy and cardiac support therapy preserves left ventricular function in rodent model of myocardial ischemia. J Thorac Cardiovasc Surg. 2010 Dec;140(6):1374-1380 Authors: Mokashi SA, Guan J, Wang D, Tchantchaleishvili V, Brigham M, Lipsitz S, Lee LS, Schmitto JD, Bolman RM, Khademhosseini A, Liao R, Chen FY OBJECTIVE: Cellular and mechanical treatment to prevent heart failure each holds therapeutic promise but together have not been reported yet. The goal of the present study was to determine whether combining a cardiac support device with cell-based therapy could prevent adverse left ventricular remodeling, more than either therapy alone. METHODS: The present study was completed in 2 parts. In the first part, mesenchymal stem cells were isolated from rodent femurs and seeded on a collagen-based scaffold. In the second part, myocardial infarction was induced in 60 rats. The 24 survivors were randomly assigned to 1 of 4 groups: control, stem cell therapy, cardiac support device, and a combination of stem cell therapy and cardiac support device. Left ventricular function was measured with biweekly echocardiography, followed by end-of-life histopathologic analysis at 6 weeks. RESULTS: After myocardial infarction and treatment intervention, the ejection fraction remained preserved (74.9-80.2%) in the combination group at an early point (2 weeks) compared with the control group (66.2-82.8%). By 6 weeks, the combination therapy group had a significantly greater fractional area of change compared with the control group (69.2% ± 6.7% and 49.5% ± 6.1% respectively, P = .03). Also, at 6 weeks, the left ventricular wall thickness was greater in the combination group than in the stem cell therapy alone group (1.79 ± 0.11 and 1.33 ± 0.13, respectively, P = .02). CONCLUSIONS: Combining a cardiac support device with stem cell therapy preserves left ventricular function after myocardial infarction, more than either therapy alone. Furthermore, stem cell delivery using a cardiac support device is a novel delivery approach for cell-based therapies. PMID: 21078426 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | [Role of MMP-9 in hematopoietic stem cell niche]. Seikagaku. 2010 Oct;82(10):979-84 Authors: Hattori K, Tashiro Y PMID: 21077332 [PubMed - in process] | | | | | | | | | |  | |  | |  |
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