[Effect of osteoblast conditioned culture medium on differentiation of BMSCs].

OBJECTIVE: To study the effect of rat osteoblast conditioned culture medium on the BMSCs differentiation of allogeneic rat and to find a new approach to provide seed cells for bone tissue engineering. METHODS: BMSCs and osteoblasts were harvested from 10 healthy one-week-old SD rats (male and female, weighing 20-30 g) by adherent method and enzyme digestion method respectively. Cell identification was conducted. Osteoblast conditioned culture medium was prepared by mixing supernatant of osteoblasts at passage 1-5 with complete medium (1:1). Then, BMSCs at passage 2 were co-cultured with osteoblast conditioned culture medium (inducement group) and complete medium (control group), respectively. The morphological changes of co-cultured BMSCs were observed by inverted phase contrast microscope, the growth condition of BMSCs was detected by MTT method, the expressions of ALP, Col I and osteocalcin (OCN) in the co-cultured BMSCs were tested by immunohistochemistry staining, and the expressions of Col I and OCN mRNA were detected by RT-PCR. RESULTS: In the inducement group, BMSCs grew bigger, changing from long fusiform to flat and polygon with protuberance 7 days after co-culture; the presence of cell colony-like growth was observed 9 days after co-culture. Cell growth curve demonstrated that the counts of BMSCs was increased with time, there were more cells in the control group than that of the inducement group, and there was a significant difference in cell counts between the control and the inducement group 4-7 days after co-culture (P < 0.05). For the inducement group, ALP staining was positive 12 days after co-culture, the calcium nodules were appeared 18 days after co-culture, Col I and OCN were positive 21 days after co-culture, and the expressions of Col I and OCN mRNA were detected by RT-PCR 21 days after co-culture. CONCLUSION: Rat osteoblast conditioned culture medium can significantly induce the differentiation of allogeneic rats' BMSCs towards osteoblasts.

Performance modification of chitosan membranes induced by gamma irradiation.

Trauma of the nervous system often results in permanent functional loss because the spontaneous regeneration of nerves is very difficult. Thus, various methods have been developed to facilitate the restoration of damaged nerve. The biodegradable nerve conduit is one of the most promising methods for nerve regeneration. Chitosan, a natural polysaccharide that has excellent biocompatibility and biodegradability, can be used as conduit material. But, nerves regenerated by nerve conduits made from chitosan have some problems, for example, with their mechanical properties. This article shows that the mechanical properties of chitosan film were markedly improved by selected doses of gamma radiation and cell culturing experiments on the surface of the irradiated chitosan film indicated that the film still has excellent biocompatibility.

[Study on chitosan and PHBHHx used as nerve regeneration conduit material].

Both Chitosan and PHBHHx are natural, biodegradable biomedical materials. In this article, their ability to be made as nerve regeneration conduits are evaluated by studying their wettability, changes of the second structure of protein absorbed on their surface, growing status of fetal rat cerebral cortex nerve cells cultured on them, mechanical properties and ability to be processed later. The results indicate that both Chitosan and PHBHHx are promising nerve conduit materials.