Long-term safety of the carbon fiber as an implant scaffold material.

Permanent therapeutically placed implants often used in situations when regeneration or transplantation are not practical or possible. They include metallic grafts for osteosynthesis, bulk metallic glasses, ceramics, and non-resorbable polymers providing mechanical support. Repair of the tissues on micro scale can also benefit from the biocompatible permanent implants. Vascular graft engineering and repairs of the spinal cord and peripheral nerves are among the most demanding application. Carbon fibers (CF) have superior mechanical and chemical properties, however, their long-time safety was never systematically estimated. The biggest concern comes from residual polymers used for pyrolysis and epoxy laminating resins. Here we attempted to investigate survival of the cells cultured on carbon fibers and to evaluate the tissue responses towards the long-term implanted material. Immortalized rat Schwann cells displayed efficient sporadic attachment to the carbon fibers with survival rate over 90%. Carbon fiber implants in adipose and on connective tissues were tolerable by animals during about 40% of their lifespan with no signs of inflammation on physiological, morphological or gene expression level.