Osteoblast-like cell response to titanium coated with co-immobilized Elastin-like polymers containing integrin-binding and Statherin-derived biomimetic peptides

Abstract

Endosseous implants are important options for restoring edentulous dental sites. Patients and practitioners are interested in implant systems that can osseointegrate faster and predictably in compromised patients. Recent research has shown that utilizing biomimetic peptides (i.e. RGD and SNa15) on titanium surfaces could improve osteoblastic responses. RGD is a peptide sequence important in binding nearly half of all integrins and is important in cellular adhesion. SNa15 is a modified peptide sequence from the N-terminus of the salivary protein statherin, which has been shown to be important in calcium phosphate mineral binding and nucleation. The aim of this study was to compare the in vitro outcomes associated with osseointegration (osteoblast-like cell adhesion, spreading, proliferation, and differentiation) between the titanium surfaces coated with RGD, SNa15, or a combination of the two biomimetic peptides via a covalently bound elastin-like biopolymer (p-). The co-immobilized titanium surfaces had either a 1:1 molar ratio of biomimetic peptides on separate biopolymers (pRGD and pSNa15) or a coating containing both peptides on a single biopolymer (pRGD-SNa15). Cellular adhesion, spreading, and proliferation was assessed with fluorescent labeling of actin, vinculin, and/or nuclear DNA and viewed with a light microscope. ELISA was used to determine early- and late-stage osteoblastic differentiation by measuring alkaline phosphatase and osteocalcin, respectively. Our results indicate that while titanium surfaces coated with only pRGD displayed greater cell adhesion, there were nonsignificant differences between titanium surfaces coated with elastin-like peptide polymers in terms of other osseointegration-related outcomes. We also noted a pattern that titanium surfaces coated with hydrophobic RGD-containing polymers were associated with an abnormal late stage osteoblastic differentiation pattern. In conclusion, we suggest that the co-immobilization of these biomimetic peptides via elastin-like polymers should be optimized in further research to improve their clinical applicability.