Intracerebral implantation of synthetic polymer/biopolymer matrix: a new perspective for brain repair.

Various poly (2-hydroxyethyl methacrylate)-collagen and poly (glyceryl methacrylate)-collagen composite hydrogels with varying porosities and cross-linking densities were implanted into the cortex of adult rat brains to provide mechanical guiding substrates for wound healing and tissue ingrowth. The hydrogels were well tolerated by the neural tissue. After 2 and 3 month, hyper- and macroporous hydrogels (poly(glyceryl methacrylate)) with interconnected channel systems were penetrated by neural tissue and elements of extracellular matrices, with differences in the degree and the topographic patterning of tissue ingrowth according to the type of samples. These differences were ascribed to the geometry, size of the pore interconnections and the mechanical properties of the polymers. Hyper- and microporous hydrogels (poly(2-hydroxyethyl methacrylate)) and hydrogels without collagen were not penetrated by the host tissue. The compatibility of the polymers with the neural tissue was also tested in vitro. This study suggests a new approach to repair brain lesions consisting of loss of tissue volume.