1,25-Dihydroxyvitamin D3 stimulates bone neovascularization by enhancing the interactions of osteoblasts-like cells and endothelial cells.

The current work investigated whether 1,25-dihydroxyvitamin D(3)(1,25-(OH)(2)D(3)) can promote the neovascularization of tissue-engineered bone. Human osteoblast-like cells (HOB) and endothelial cells (EC) were isolated and cultured. HOB and EC were inoculated at the ratio of 2:1 onto the coral-derived hydroxyapatite (CHA) scaffolds coated with and without 1,25-(OH)(2)D(3). Tissue-engineered bones were cultured for 3 days before implantation into the backs of nude mice. Four and 8 weeks after the operation, the retrieved scaffolds and cells were examined histologically and by scanning electron microscope, and the vascular area was measured. The immature bone grew into the pores of CHA scaffolds in both groups. At each time interval, there was a conspicuous neovascularization in the 1,25-(OH)(2)D(3) treatment group, with a larger amount of new capillaries accompanying immature bone. In the 1,25-(OH)(2)D(3) group, scanning electron microscopy revealed luminal sprouting from the larger vessels. Maturation of the new bone was paralleled by the occurrence of the new capillaries. The vascular areas were 28.74% +/- 7.81% and 19.52% +/- 4.57% at 4-week intervals (p < 0.05) and 24.66% +/- 7.38% and 17.84% +/- 5.22% at 8-week intervals (p < 0.05) in test and control groups, respectively. These results imply that 1,25-dihydroxyvitamin D(3) may be useful as a cytokine for tissue engineering bone for neovascularization.