Incorporation of graphene oxide into collagenous biomaterials attenuates scar-forming phenotype transition of reactive astrocytes in vitro

The integrin-mediated interaction between collagen type I and reactive astrocytes was recently shown to induce a detrimental, scar-forming phenotype transformation following spinal cord injury (SCI), which severely limits the therapeutic potential of commonly used collagen-based biomaterials. Graphene oxide (GO) is a promising candidate to disrupt the collagen-integrin interaction, since it is capable of altering the surface topography of biomaterials applied as SCI treatment. Moreover, free GO contributes towards potassium and glutamate transport, which is often implicated following SCI. However, it remains unclear whether both the integrin-mediated binding and astrocytic transport of potassium and glutamate are affected by GO, when inserted into collagenous biomaterials. Therefore, in the current study GO was incorporated into collagen-based hydrogels in an attempt to prevent the scar-forming phenotype transition and promote the expression of astrocytic potassium channels and glutamate transporters. Primary astrocytes were cultured either on top of or embedded within GO-enriched collagen type I or adipose tissue-derived extracellular matrix (ECM) gels. The impact of GO incorporation on integrin β1-mediated binding, astrocyte phenotype and potassium and glutamate transport was assessed by gene expression analysis and immunofluorescence studies. Upon GO incorporation into ECM gels, expression of integrin β1 and N-cadherin was significantly decreased. Moreover, GO decreased proteoglycan-associated gene expression by four-fold. Finally, GO incorporation led to a decrease in expression of both potassium channels and glutamate transporters. In conclusion, the incorporation of GO into collagen-based materials attenuated the transition of reactive astrocytes into a scar-forming phenotype.