The enhanced angiogenic responses to ionic dissolution products from a boron-incorporated calcium silicate coating.

Early vascularization is crucial for osteogenic repair of bone defects and plays an essential role in the fate of implanted biomaterials. Thus, there is a growing interest in the use of biomaterials to release inorganic ions that are capable of stimulating angiogenesis. Since it has been established that boron (B) may play roles in angiogenesis, the aim of our study was to investigate the in vitro angiogenic effects of the ionic dissolution products from the B-incorporated calcium silicate (Ca11Si4B2O22, B-CS) coating. The results showed that ionic products of B-CS coating extract obviously stimulated the proliferation and migration of human umbilical vein endothelial cells (HUVECs) as well as the in vitro tubule formation when compared with those of CS coating extract. In addition, the gene expression levels of pro-angiogenic growth factors (VEGF, bFGF, ANG1) and receptors (VEGFR-2, bFGFR) were significantly upregulated when stimulated with the B-CS coating extract. Moreover, VEGF and VEGFR-2 protein synthesis, eNOS, and Akt phosphorylation, as well as NO synthesized by HUVECs were increased by the B-CS coating extract. Hence, the B-CS coating offers a potential solution to enhance bone vascularization essential for successful osseointegration of orthopedic implants.