Biomaterials
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Comparative Study
Repair of articular cartilage defects treated by microfracture and a three-dimensional collagen matrix.
The objective of our study was to evaluate the behavior of ovine chondrocytes and bone marrow stromal cells (BMSC) on a matrix comprising type-I, -II, and -III collagen in vitro, and the healing of chondral defects in an ovine model treated with the matrix, either unseeded or seeded with autologous chondrocytes, combined with microfracture treatment. For in vitro investigation, ovine chondrocytes and BMSC were seeded on the matrix and cultured at different time points. Histological analysis, immunohistochemistry, biochemical assays for glycosaminoglycans, and real-time quantitative PCR for collagens were performed. ⋯ The cell-seeded group had the greatest quantity of repair tissue and the largest quantity of hyaline-like tissue. Although the collagen matrix is an adequate environment for BMSC in vitro, the additionally implanted unseeded collagen matrix did not increase the repair response after microfracture in chondral defects. Only the matrices seeded with autologous cells in combination with microfracture were able to facilitate the regeneration of hyaline-like cartilage.
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Degrading metal alloys are a new class of implant materials suitable for bone surgery. The aim of this study was to investigate the degradation mechanism at the bone-implant interface of different degrading magnesium alloys in bone and to determine their effect on the surrounding bone. Sample rods of four different magnesium alloys and a degradable polymer as a control were implanted intramedullary into the femora of guinea pigs. ⋯ While the corrosion layer of all magnesium alloys accumulated with biological calcium phosphates, the corrosion layer was in direct contact with the surrounding bone. The results further showed high mineral apposition rates and an increased bone mass around the magnesium rods, while no bone was induced in the surrounding soft tissue. From the results of this study, there is a strong rationale that in this research model, high magnesium ion concentration could lead to bone cell activation.
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Comparative Study
High-strength apatitic cement by modification with superplasticizers.
This study reports on a novel method to improve the strength of apatitic bone cements. The liquid phase of Biocement-H was modified with commercial superplasticizers. ⋯ Moreover, the addition of high amounts of superplasticizers, i.e. 50 vol.%, allowed for a significant reduction of the liquid-to-powder ratio from 0.32 to 0.256 mL/g, without affecting the maximum strength and/or the workability of the cement. These results open up new ways to develop injectable and high-strength apatitic bone cements for load-bearing applications.
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Polyimide sieve electrodes were implanted between the severed ends of the sciatic nerve in rats. The degree of axonal regeneration through the electrode was examined by physiological and histological methods from 2 to 12 months postimplantation. Regeneration was successful in the 30 animals implanted. ⋯ However, in a few cases decline of target reinnervation and loss of regenerated nerve fibers was found from 6 to 12 months postimplantation. Motor axons labeled by ChAT immunoreactivity regenerated scattered within minifascicles, although they were found at higher density at the periphery of the regenerated nerve. The number of ChAT-positive axons was markedly lower distally than proximally to the sieve electrode.
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Comparative Study
A three-dimensional nanofibrous scaffold for cartilage tissue engineering using human mesenchymal stem cells.
The utilization of adult stem cells in tissue engineering is a promising solution to the problem of tissue or organ shortage. Adult bone marrow derived mesenchymal stem cells (MSCs) are undifferentiated, multipotential cells which are capable of giving rise to chondrocytes when maintained in a three-dimensional culture and treated with members of the transforming growth factor-beta (TGF-beta) family of growth factors. In this study, we fabricated a nanofibrous scaffold (NFS) made of a synthetic biodegradable polymer, poly(-caprolactone) (PCL), and examined its ability to support in vitro chondrogenesis of MSCs. ⋯ MSCs cultured in NFSs in the presence of TGF-beta1 differentiated to a chondrocytic phenotype, as evidenced by chondrocyte-specific gene expression and synthesis of cartilage-associated extracellular matrix (ECM) proteins. The level of chondrogenesis observed in MSCs seeded within NFSs was comparable to that observed for MSCs maintained as cell aggregates or pellets, a widely used culture protocol for studying chondrogenesis of MSCs in vitro. Due to the physical nature and improved mechanical properties of NFSs, particularly in comparison to cell pellets, the findings reported here suggest that the PCL NFS is a practical carrier for MSC transplantation, and represents a candidate scaffold for cell-based tissue engineering approaches to cartilage repair.