Effect of chitosan-polyvinyl pyrrolidone hydrogel on proliferation and cytokine expression of endothelial cells: Implications in islet immunoisolation

Earlier we have shown the suitability of chitosan-polyvinyl pyrrolidone (PV P) hydrogel for islet immunoisolation and its inability to activate macroph ages. Biomaterials that support vascularization without activatin- immune c ompetent endothelial cells are desirous in islet immunoisolation. The aim o f the present study was to evaluate effect of chitosan-PVP hydrogel on prol iferation and activation of endothelial cells. Hydrogel did not allow the m ajority of cells to adhere well ut maintained their viability. Hydrogel lea chouts were nontoxic to the cells, as confirmed by tetrazolium reduction (M TT) and Neutral red uptake assays. Exposure to leachouts also did not alter their functional tv as seen from normal expression of von Willebrand facto r. -H-3-thymidine incorporation revealed that hydrogel leachouts did not in duce endothelial cell proliferation. Cells cultured on hydrogel and polysty rene control showed comparable expression of interleukin (IL) 6, IL-10, and transforming growth factor beta, with higher expression of tumor necrosis factor alpha as determined by reverse transcription-polymerase chain reacti on. Taken together these results point out that hydrogel is compatible with endothelial cells and maintains their nonactivated status and hence is sui table as immunoisolation matrix. (C) 2001 John Wiley & Sons, Inc.