Abstract
Thermoreversible polymers based on N‐isopropylacrylamide (NiPAM) are being explored for tissue engineering applications. The polymers exhibit a solubility change as a function of temperature, which could be utilized for convenient delivery of proteins and cells. Being synthetic, however, the polymer does not allow direct cell attachment. To overcome this limitation, Arginine‐Glycine‐Aspartic Acid (RGD)‐containing peptides were grafted to the polymers in this study. Attachment of rat bone marrow stromal cells (BMSC) on NiPAM‐based polymers was increased by RGD‐grafting, but long‐term cell growth was not as robust as the BMSC grown on tissue culture polystyrene. However, the expression of specific alkaline phosphate activity (ALP/cell; an osteogenic marker) was elevated for cells grown on polymer films and RGD‐grafting was not beneficial in this regard. Whereas basic Fibroblast Growth Factor suppressed the ALP/cell activity, Bone Morphogenetic Protein‐2 stimulated ALP/cells activity for cells grown on polymer films. These results were in line with our previous studies on the osteogenic response of a cell line (C2C12) and stressed the need to improve cell proliferation on NiPAM surfaces, while preserving the beneficial effect of the polymer on osteogenic markers.