| Tissue engineering with adipose-derived stem cells (ADSCs): current and future applications.
December 9, 2009 at 9:33 am
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| | Tissue engineering with adipose-derived stem cells (ADSCs): current and future applications. J Plast Reconstr Aesthet Surg. 2009 Dec 6; Authors: Sterodimas A, de Faria J, Nicaretta B, Pitanguy I Soft-tissue loss presents an ongoing challenge in plastic and reconstructive surgery. Standard approaches to soft-tissue reconstruction include autologous tissue flaps, autologous fat transplantation and alloplastic implants. All of these approaches have disadvantages, including donor-site morbidity, implant migration and absorption and foreign body reaction. Stem cell application has recently been suggested as a possible novel therapy. Adipose-derived stem cells (ADSCs) are an abundant, readily available population of multipotent progenitor cells that reside in adipose tissue, which is an easily accessible and abundant source of putative stem cells for translational clinical research. Their therapeutic use in pre-clinical studies and experimental clinical trials has been well documented. We present the current strategies of tissue engineering with ADSC and we discuss the possible future applications of this new method in the field of plastic and reconstructive surgery. Complete understanding of the mechanisms of interactions among adipose stem cells, growth factors and biomaterials in tissue engineering is still lacking. Adipose tissue stem cell-based regenerative strategies hold tremendous promise, although this potential must be balanced against stringent standards of scientific and clinical investigation, before developing 'off-the-shelf' tissue engineering products. PMID: 19969517 [PubMed - as supplied by publisher] |
| Simulation of angiogenesis and cell differentiation in a CaP scaffold subjected to compressive strains using a lattice modeling approach.
December 9, 2009 at 9:33 am
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| | Simulation of angiogenesis and cell differentiation in a CaP scaffold subjected to compressive strains using a lattice modeling approach. Biomaterials. 2009 Dec 5; Authors: Sandino C, Checa S, Prendergast PJ, Lacroix D Mechanical stimuli are one of the factors that influence tissue differentiation. In the development of biomaterials for bone tissue engineering, mechanical stimuli and formation of a vascular network that transport oxygen to cells within the pores of the scaffolds are essential. Angiogenesis and cell differentiation have been simulated in scaffolds of regular porosity; however, the dynamics of differentiation can be different when the porosity is not uniform. The objective of this study was to investigate the effect of the mechanical stimuli and the capillary network formation on cell differentiation within a scaffold of irregular morphology. A porous scaffold of calcium phosphate based glass was used. The pores and the solid phase were discretized using micro computed tomography images. Cell activity was simulated within the interconnected pore domain of the scaffold using a lattice modeling approach. Compressive strains of 0.5 and 1% of total deformation were applied and two cases of mesenchymal stem cells initialization (in vitro seeding and in vivo) were simulated. Similar capillary networks were formed independently of the cell initialization mode and the magnitude of the mechanical strain applied. Most of vessels grew in the pores at the periphery of the scaffolds and were blocked by the walls of the scaffold. When 0.5% of strain was applied, 70% of the pore volume was affected by mechano-regulatory stimuli corresponding to bone formation; however, because of the lack of oxygen, only 40% of the volume was filled with osteoblasts. 40% of volume was filled with chondrocytes and 3% with fibroblasts. When the mechanical strain was increased to 1%, 11% of the pore volume was filled with osteoblasts, 59% with chondrocytes, and 8% with fibroblasts. This study has shown the dynamics of the correlation between mechanical load, angiogenesis and tissue differentiation within a scaffold with irregular morphology. PMID: 19969348 [PubMed - as supplied by publisher] |
| Incorporation of double-walled microspheres into polymer nerve guides for the sustained delivery of glial cell line-derived neurotrophic factor.
December 9, 2009 at 9:33 am
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| | Incorporation of double-walled microspheres into polymer nerve guides for the sustained delivery of glial cell line-derived neurotrophic factor. Biomaterials. 2009 Dec 6; Authors: Kokai LE, Ghaznavi AM, Marra KG The purpose of this study was to develop a biodegradable polymer nerve guide that locally delivers bioactive neurotrophic factors in physiologically relevant concentrations for the period required by transected peripheral nerves to cross from the proximal to distal nerve stump. Delivery of a neurotrophic factor may enhance nerve regeneration and could potentially be used to overcome the current limitations in nerve repair across large defects. Glial Cell Line-Derived Neurotrophic Factor (GDNF) is a known promoter of axonal elongation and branching and has shown promising pre-clinical results in analysis of nerve regeneration with nerve guides. In addition, GDNF has been shown to promote Schwann cell proliferation and migration. In this study we have created a double-walled microsphere delivery system for bioactive GDNF with a sustained release profile >50 days in vitro. Microspheres were incorporated within degradable poly(caprolactone) nerve guides in a reproducible distribution. Implantation of nerve guides across a 1.5cm defect in a rat sciatic nerve gap resulted in an increase in tissue integration in both the proximal and distal segments of the lumen of the nerve guide after 6 weeks. In addition, transverse sections of the distal region of the explanted guides showed the presence of Schwann cells while none were detectable in negative control guides. Migration of Schwann cells to double-walled microspheres indicated that bioactive GDNF was encapsulated and delivered to the internal environment of the nerve guide. Because GDNF increased tissue formation within the nerve guide lumen and also promoted the migration and proliferation of Schwann cells, the nerve guides presented within this study show promise toward the development of an off-the-shelf product alternative that promotes nerve regeneration beyond that capable with currently available nerve guides. PMID: 19969346 [PubMed - as supplied by publisher] |
| Bioceramics of calcium orthophosphates.
December 9, 2009 at 9:33 am
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| | Bioceramics of calcium orthophosphates. Biomaterials. 2009 Dec 6; Authors: Dorozhkin SV A strong interest in use of ceramics for biomedical applications appeared in the late 1960's. Used initially as alternatives to metals in order to increase a biocompatibility of implants, bioceramics have become a diverse class of biomaterials, presently including three basic types: relatively bioinert ceramics, bioactive (or surface reactive) and bioresorbable ones. Furthermore, any type of bioceramics could be porous to provide tissue ingrowth. This review is devoted to bioceramics prepared from calcium orthophosphates, which belong to the categories of bioresorbable and bioactive compounds. During the past 30-40 years, there have been a number of major advances in this field. Namely, after the initial work on development of bioceramics that was tolerated in the physiological environment, emphasis was shifted towards the use of bioceramics that interacted with bones by forming a direct chemical bond. By the structural and compositional control, it became possible to choose whether the bioceramics of calcium orthophosphates was biologically stable once incorporated within the skeletal structure or whether it was resorbed over time. At the turn of the millennium, a new concept of calcium orthophosphate bioceramics, which is able to regenerate bone tissues, has been developed. Current biomedical applications of calcium orthophosphate bioceramics include replacements for hips, knees, teeth, tendons and ligaments, as well as repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jawbone, spinal fusion and bone fillers after tumor surgery. Potential future applications of calcium orthophosphate bioceramics will include drug-delivery systems, as well as they will become effective carriers of growth factors, bioactive peptides and/or various types of cells for tissue engineering purposes. PMID: 19969343 [PubMed - as supplied by publisher] |
| Stable modification of poly (lactic acid) surface with neurite outgrowth-promoting peptides via hydrophobic collagen-like sequence.
December 9, 2009 at 9:33 am
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| | Stable modification of poly (lactic acid) surface with neurite outgrowth-promoting peptides via hydrophobic collagen-like sequence. Acta Biomater. 2009 Dec 4; Authors: Kakinoki S, Yamaoka T Surface modification of poly (DL-lactic acid) scaffolds has been performed with biofunctional small peptide composed of collagen-like repetitive sequence and laminin-derived sequence (AG73-G(3)-(PPG)(5)) via hydrophobic interaction. As the results of surface analysis, it is suggested that AG73-G(3)-(PPG)(5) could be stably adsorbed onto PLA films via hydrophobic interaction at (PPG)(5) region, and form extracellular matrix-like layer composed of both structural and biosignalling sequences. In addition, neurite outgrowth of PC12 cells was observed on the AG73-G(3)-(PPG)(5) adsorbed PLA film. These results indicate that AG73-G(3)-(PPG)(5) very effectively enhances neurite outgrowth activity on PLA films. The hydrophobic adsorption of collagen-like peptide bound to biosignalling molecules may be widely applied as a surface modifier of PLA film for tissue engineering. PMID: 19969110 [PubMed - as supplied by publisher] |
| [Effects of NGF on proliferation, mitotic cycle, collagen synthesis and migration of human dermal fibroblasts in vitro]
December 9, 2009 at 9:33 am
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| | [Effects of NGF on proliferation, mitotic cycle, collagen synthesis and migration of human dermal fibroblasts in vitro] Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2009 Nov;23(11):1350-4 Authors: Gan H, Xie H, Chen X, Luo J OBJECTIVE: To investigate the effects of NGF on the proliferation, mitotic cycle, collagen synthesis and migration of human dermal fibroblasts (HDFs), and to explore the function of NGF on the wound healing. METHODS: The 3rd generation of HDFs were incubated with various concentrations of NGF (0, 25, 50, 100, 200 and 400 ng/mL), the cell proliferation was measured with MTT assay. After treated with NGF at 0, 100 ng/mL, the cell cycle of HDFs was determined by flow cytometry (FCM). Hydroxyproline and real-time fluorescence quantitative PCR (FQ-PCR) were used to measure collagen synthesis at protein level and mRNA level respectively. The in vitro cell scratch wound model was set up to observe the effect of NGF (0, 50, 100 and 200 ng/mL) on the migration of HDFs after 24 hours of culture. RESULTS: Absorbance value of HDFs for different concentrations of NGF (0, 25, 50, 100, 200, and 400 ng/mL) showed that NGF did not influence the proliferation of HDFs (P > 0.05). When HDFs were treated with NGF at 0 and 100 ng/mL, the result of FCM analysis showed that percentage of HDFs in G0/G1, S, G2/M phases were not changed (P > 0.05). Compared with control group, the expression of Col I and Col III were not significantly different, measured by both hydroxyproline and FQ-PCR (P > 0.05). The rates of HDFs' migration at various concentrations of NGF (0, 50, 100, 200 ng/mL) were 52.12% +/- 6.50%, 80.67% +/- 8.51%, 66.33% +/- 3.58%, and 61.19% +/- 0.97%, respectively, indicating that NGF could significantly enhanced the migration of HDFs at 50 and 100 ng/mL (P < 0.05). CONCLUSION: NGF does not influence proliferation, mitotic cycle and collagen synthesis of HDFs, but significantly enhanced migration in an in vitro model of wounded fibroblasts. PMID: 19968179 [PubMed - in process] | | | 
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