Finally, the impact of BMP adsorption on cell phenotype was explored. To do so, we focused on BMP2 functionalised PSPMA brushes, owing to its more extensive adsorption and stability, and examined the impact of the brush architecture on the cell response to growth factor binding. BMPs play an important role in skin development and regulate some of the processes orchestrating interactions between dermal and epidermal compartments , as well as controlling matrix remodelling in other contexts . Hence we examined the impact of BMP2 immobilisation on PSPMA brushes on the deposition of ECM by dermal fibroblasts. Fibroblasts seeded on PSPMA brushes in the absence of BMP2 spread very slowly and sparsely, regardless of the thickness and density of the brush (Figure and Supplementary Figure ). This was particularly striking on dense and thick polymer brushes (HD-30), for which few spread cells could be seen even at day 3 post-seeding. However, by day 7, all substrates were fully covered by dense fibroblast monolayers. We noted the formation of cell clusters on thin PSPMA brushes, whether generated from dense or sparse initiator monolayers. In contrast, fibroblasts spread more rapidly on all PSPMA brushes coated with BMP2. Regardless of their architecture and the adsorption of BMP2, all substrates were found to be coated by dense fibroblasts layers after 7 days of culture.