Additive effect of RGD coating to functionalized titanium surfaces on human osteoprogenitor cell adhesion and spreading

Titanium-based biomaterials for endosseous implants have found widespread applications in the orthopedic, maxillofacial, and dental domains. Indeed, the surface characteristics such as their chemical modification control considerably the cellular response and, subsequently, the quality and the quantity of new-formed bone around the implant. In this study, human osteoprogenitor (HOP) cell adhesion on different titanium surfaces functionalized with hydroxyapatite (HA), type I collagen, or Arg-Gly-Asp (RGD)-containing peptides is investigated by the quartz crystal resonators and by confocal laser scanning microscopy (CLSM) for the imaging of focal contact formation. Data obtained by quartz crystal resonator technique revealed that RGD-containing peptides alone increase HOP cell adhesion in early time period of culture. Moreover, association of RGD-containing peptides with either type I collagen or with HA layers induces an additive effect on HOP cell adhesion compared to Ti-Coll or Ti-HA. CLSM shows both the area of focal contact by cell unit and the cytoskeleton network organization to differ according to the surfaces. Interestingly, association of RGD-containing peptides with HA layers induces an additive effect on focal contact formation on HOP cells compared to Ti-HA alone. These data confirm that an RGD peptide effect occurs in the early time of culture, which is beneficial for osteoblast to spreading, differentiation, and survival.