Bioactive surface for neural electrodes: decreasing astrocyte proliferation via transforming growth factor-beta1

Implantation of deep-brain recording devices is a traumatic event, which inevitably elicits reactive gliosis. The ensuing glial scar encapsulating the implanted device impedes the long-term functional recording capability of the microelectrode. In this work, a bioactive surface is prepared by conjugation of transforming growth factor-beta one (TGF-beta1) and laminin to dextran, which is in turn conjugated to a biomaterial substrate. Poly-L-lysine coated surfaces are treated with oxidized dextran, and the dextran is re-oxidized with sodium metaperiodate to generate hemiacetal structures to which TGF-beta1 and laminin are covalently bound. Covalent conjugation of the ligand is confirmed by enzyme-linked immunosorbent assay. A primary cell line of astrocytes is incubated on a surface conjugated with laminin and TGF-beta1 and a surface only conjugated with laminin. Proliferation on the laminin plus TGF-beta1 surface is 57% less (p < 0.002) than the control surface (laminin alone). The results demonstrate that conjugated TGF-beta1 retains its efficacy toward astrocyte proliferation and represents a potential strategy for reducing glial scar formation in vivo.