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 (PVP) hydrogel for islet immunoisolation and its inability to activate macrophages. Biomaterials that support vascularization without activating immune competent endothelial cells are desirous in islet immunoisolation. The aim of the present study was to evaluate effect of chitosan-PVP hydrogel on proliferation and activation of endothelial cells. Hydrogel did not allow the majority of cells to adhere well but maintained their viability. Hydrogel leachouts were nontoxic to the cells, as confirmed by tetrazolium reduction (MTT) and Neutral red uptake assays. Exposure to leachouts also did not alter their functionality as seen from normal expression of von Willebrand factor. ³H-thymidine incorporation revealed that hydrogel leachouts did not induce endothelial cell proliferation. Cells cultured on hydrogel and polystyrene control showed comparable expression of interleukin (IL) 6, IL-10, and transforming growth factor β, with higher expression of tumor necrosis factor α as determined by reverse transcription-polymerase chain reaction. Taken together these results point out that hydrogel is compatible with endothelial cells and maintains their nonactivated status and hence is suitable as immunoisolation matrix. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res 57: 300–305, 2001