Surface Grafted Adenosine Diphosphate Affects Platelet Functions

Objectives: Endosseous dental implants have been successfully used in dentistry for many years. For faster and more predictable osseointegration, implant surface has been modified using various methods. Platelets are important players in healing process. It has been shown that adenosine diphosphate (ADP) can attract and activate platelets. The bioactive molecules released by activated platelets may significantly enhance osseointegration. This study aims to modify implant surface by grafted adenosine diphosphate (G-ADP) to promote platelet adhesion, aggregation and activation.
Methods: ADP was grafted onto a base material surface (glass slide) by coupling effect of polydopamine (G-ADP group). Dopamine coated glass slides (G-DA group) and uncoated glass slides (G group) were two control groups. X-ray photoelectron spectroscopy(XPS) was performed to detect whether ADP was successfully grafted to the surface. Scanning electron microscope (SEM), lactate dehydrogenase (LDH) quantitative assay and immunofluorescence marker assay were performed to demonstrate the amount, morphology and activity of the adhered platelets. Human mesenchymal stromal cells(MSCs) were cultured on the surface and proliferation was assessed to demonstrate biocompatibility. The results were analyzed by one-way analysis of variance(ANOVA, p<0.05).
Results: XPS showed that the coated surface appeared P peaks indicating the abundance of ADP. Under SEM, G-ADP surface was covered by a large number of platelets-like cells gathered in clusters, while the controls weren’t. LDH assay evaluated quantitatively the adhesion amounts of platelets. The results of three groups were G-ADP(1890±98.90 IU), G-DA(1279±38.03 IU), G(157±43.49 IU) (P<0.05). Immunofluorescent staining of platelet markers proved that these cells were indeed activated platelets. MSCs proliferation results showed cell number of three groups rose respectively, with no significant differences in 1,3,5 days (P>0.05).
Conclusions: Within the limitations of this study, we conclude that ADP can be successfully grafted onto the surface and the functionalized surface can promote adhesion, aggregation and activation of platelets with good biocompatibility.