Biomimetic peptide surfaces that regulate adhesion, spreading, cytoskeletal organization, and mineralization of the matrix deposited by osteoblast-like cells

In an effort to regulate mammalian cell behavior in contact with solid mate rial surfaces, we have functionalized surfaces with different ratios of bot h the putative cell binding (-Arg-Gly-Asp-) domain and a consensus heparan- binding domain. The peptide sequences -Arg-Gly-Asp- (-RGD-) and -Phe-His-Ar g-Arg-Ile-Lys-Ala- (-FHRRIKA-) or mixtures of the two in the ratios of 75:2 5 (mimetic peptide surface I), 25:75 (mimetic peptide surface II), and 50:5 0 (mimetic peptide surface III) were immobilized on model surfaces using a heterobifunctional cross-linker to link the peptide(s) to amine-functionali zed quartz surfaces. Contact angle measurements, spectroscopic ellipsometry , and X-ray photoelectron spectroscopy were used to confirm the chemistry, thickness of the overlayers, and surface density of immobilized peptides (s imilar to 4-6 pmol/cm(2)). The degree of rat calvaria osteoblast-like cell spreading, focal contact formation, cytoskeletal organization, proliferatio n, and mineralization of the extracellular matrix (ECM) on model biomateria l surfaces was examined. Mimetic peptide surface II (MPS II) and MPS III su pported the highest degree of cell spreading (p < 0.05), following 4 h of i ncubation, compared to MPS I, homogeneous -RGD-, and homogeneous -FHRRIKA- grafted surfaces. Furthermore, MPS I, MPS II, MPS III, and homogeneous -RGD - surfaces promoted the formation of focal contacts and stress fibers by at tached bone cells. The strength of bone cell detachment following 30 min of incubation was significantly higher (p < 0.05) on MPS II surfaces compared to homogeneous -RGD- and -FHRRIKA-. However, the degree of cell proliferat ion on the peptide surfaces were not significantly different from each othe r (p > 0.1). Following 24 d in culture, the areas of mineralized ECM formed on MPS II and MPS III surfaces were significantly (p < 0.05) larger than t hose of other surfaces. These results demonstrate that utilizing peptide se quences incorporating bath cell- and heparin-adhesive motifs can enhance th e degree of cell surface interactions and influence the long-term formation of mineralized ECM in vitro.