SYNTHETIC-POLYMER MATRICES FOR NEURAL CELL TRANSPLANTATION

This study proposes a strategy to promote the integration of a neural graft into the host brain tissue. It involves the attachment of donor cells to a polymeric matrix, and the implantation of this cell-polymer matrix. We have synthesized hydrogels based on N-(2-hydroxypropyl)-me thacrylamide (HPMA) to produce highly porous matrices. As preliminary steps, we have examined: 1) The response of the brain tissue to the im plantation of PHPMA/collagen hydrogels; 2) adhesion, growth, different iation, and viability of embryonic neuronal cells, and embryonal carci noma-derived neurons seeded onto PHPMA substrates containing hexosamin e residues (glucosamine and N-acetylglucosamine), and after entrapment of cells within the hydrogels. Histological analysis seven wk after i mplantation showed the tolerance of PHPMA hydrogels, and the penetrati on of host cells into the pore structures. However, cellular ingrowth requires the presence of collagen, and is dependent upon porosity. In vitro data showed that PHPMA substrates supported neuronal cell attach ment and neuritic growth, but the biocompatibility of the substrate wa s enhanced after incorporation of N-acetylglucosamine into the hydroge l. The data also showed the feasibility of entrapping cells into the p olymer matrices, and that these ''cellular'' hydrogel matrices could b e maintained in vitro with preservation of cell viability and differen tiation. These findings suggest that PHPMA-based hydrogels can serve a s carriers for neural transplant, and as a support to guide tissue ing rowth and organization.