Acrylic hydrogel implants after spinal cord lesion in the adult rat

Abstract

Acrylic hydrogels, like the polymer of 2-hydroxyethyl methacrylate, are biocompatible, mechanically stable, porous materials that can be coated with collagen or laminin acting as bioadhesive substrates. Poly- 2-hydroxyethyl methacrylate sponges have been proposed for restoring the anatomical continuity of damaged neural structures. In the present work, the ability of poly-2-hydroxyethylmethacrylate sponges to provide the injured spinal cord neurons with a conductive substrate for their regenerating axons was investigatedin 32 adultWistar rats. Collagen impregnated poly-2-hydroxyethylmethacrylatesponges were implanted into suction cavities of the dorsal funiculus of the spinal cord. Two to four months after implantation, the spinal cord was removed and processed for histology, and S100 and GFAP immunohistochemistry. To study axonal regeneration into the sponge, the spinal cord or the sensorimotor cortex were injected with 0.05–0.1 ml of an 8% solution of lectin-conjugated horseradish peroxidase or 10% dextran tetramethylrhodamine. The fibroglial reaction, accumulation of mononuclear cells, and angiogenesis at the interface between the spinal cord and the sponge were minimal. Cystic cavitation in the spinal cord was virtually absent. Anterograde labeled axons were seen to penetrate and to elongate the full length of the sponge. These results demonstrate that poly-2-hydroxyethylmethacrylate sponges represent a safe supportive material for regenerating spinal cord axons.