Cell encapsulation has been reported to convey cytoprotective effects and to better maintain cell survival. In contrast to other studies, our report shows that the deposition of two major biomacromolecules, collagen type I (Col) and hyaluronic acid (HA), on mesenchymal stem cells (MSCs) does not entirely block the cell plasma membrane surface. Instead, a considerable amount of the surface remained uncovered or only slightly covered, as confirmed by TEM observation and by FACS analysis based on quantitative surface labeling. Despite this structure showing openness and flexibility, the multilayer Col/HA films significantly increased cell survival in the attachment-deprived culture condition. In terms of stem cell characteristics, the MSCs still showed functional cell activity after film deposition, as evidenced by their colony-forming activity and in vitro osteogenic differentiation. The Col/HA multilayer films could provide a cytoprotective effect and induce osteogenic differentiation without deteriorating effect or inhibition of cellular attachment, showing that this technique can be a valuable tool for modulating stem cell activities.

BACKGROUND: Current dilemma working with surgically-induced OA (osteoarthritis) model include inconsistent pathological state due to various influence from surrounding tissues. On the contrary, biochemical induction of OA using collagenase II has several advantageous points in a sense that it does not involve surgery to induce model and the extent of induced cartilage degeneration is almost uniform. However, concerns still exists because biochemical OA model induce abrupt destruction of cartilage tissues through enzymatic digestion in a short period of time, and this might accompany systemic inflammatory response, which is rather a trait of RA (rheumatoid arthritis) than being a trait of OA. METHODS: To clear the concern about the systemic inflammatory response that might be caused by abrupt destruction of cartilage tissue, OA was induced to only one leg of an animal and the other leg was examined to confirm the presence of systemic degenerative effect. RESULTS: Although the cartilage tissues were rapidly degenerated during short period of time upon biochemical induction of OA, they did not accompanied with RA-like process based on the histology data showing degeneration of articular cartilage occurred only in the collagenase-injected knee joint. Scoring evaluation data indicated that the cartilage tissues in non-induced joint remained intact. Neutrophil count transiently increase between day 8 and day 16, and there were no significant change in other complete blood count profile showing a characteristics of OA disease. CONCLUSION: These study shows that biochemically induced cartilage degeneration truly represented uniform and reliable OA state.