Differentiation of human adipose-derived stem cells seeded on mineralized electrospun co-axial poly(ε-caprolactone) (PCL)/gelatin nanofibers.

Mineralized poly(ε-caprolactone)/gelatin core-shell nanofibers were prepared via co-axial electrospinning and subsequent incubation in biomimetic simulated body fluid containing ten times the calcium and phosphate ion concentrations found in human blood plasma. The deposition of calcium phosphate on the nanofiber surfaces was investigated through scanning electronic microscopy and X-ray diffraction. Energy dispersive spectroscopy results indicated that calcium-deficient hydroxyapatite had grown on the fibers. Fourier transform infrared spectroscopy analysis suggested the presence of hydroxyl-carbonate-apatite. The results of a viability assay (MTT) and alkaline phosphatase activity analysis suggested that these mineralized matrices promote osteogenic differentiation of human adipose-derived stem cells (hASCs) when cultured in an osteogenic medium and have the potential to be used as a scaffold in bone tissue engineering. hASCs cultured in the presence of nanofibers in endothelial differentiation medium showed lower rates of proliferation than cells cultured without the nanofibers. However, endothelial cell markers were detected in cells cultured in the presence of nanofibers in endothelial differentiation medium.

Photopolymerizable and injectable polyurethanes for biomedical applications: synthesis and biocompatibility.

Two types of photopolymerizable and injectable polyurethane acrylates (PUAs), based on poly(propylene glycol) or poly(caprolactone diol) and hydroxyethyl methacrylate, were synthesized and characterized in order to obtain information regarding their use as an injectable material for biomedical applications. Structural characteristics of the biomaterials, including the degree of phase separation, were evaluated by Fourier transform infrared spectroscopy. The viscosities of the obtained biomaterials make them suitable for injection, molding and photopolymerization using visible light, as demonstrated by the injection test. The cured polymers had mechanical properties comparable to those of certain soft tissues, such as skin. An in vitro cell-polyurethane cytotoxicity study was carried out with mesenchymal stem cells from rat tibias and femurs. The proliferation/viability of the cells in the presence of the synthesized material was assessed by the MTT assay, collagen synthesis analysis and the expression of alkaline phosphatase. The results that were obtained through the in vitro tests indicated that PUAs are cytocompatible. The in vivo experiments were correlated with the in vitro tests and showed low levels of toxicity for the obtained biomaterials. Histology cross-sections showed that the biomaterials induced no significant inflammatory reaction. Our study demonstrates the potential for using synthesized photocurable polyurethanes in biomedical applications. Furthermore, the obtained injectable polymer systems employ minimally invasive procedures and can be molded in situ before photopolymerization with visible light.