Expression of the proangiogenic protein hepatoma-derived growth factor in neovessels in an arterial venous loop-based tissue engineering chamber

Boosting angiogenesis is a crucial process to enhance tissue growth in tissue engineering (TE). Hepatoma-derived growth factor (HDGF) has been identified as an angiogenic factor, but its involvement in angiogenesis in an arteriovenous loop-based TE chamber developed by the laboratory is unclear. In this study, the authors first examined the effects of HDGF on angiogenic responses in endothelial cells and in a corneal model of neovascularization, and then characterized the expression of HDGF in the TE chamber. HDGF (1–500 ng/mL) induced concentration-dependent angiogenic responses in human endothelial cells in vitro (proliferation, migration, and tube formation). Local application of HDGF stimulated neovascularization in a rat model of corneal angiogenesis. In the TE chamber, there was an increase in blood vessel volume from day 3 to day 14. Immunofluorescence microscopy revealed that HDGF is highly expressed in the neovessels in the chamber. Peak expression of HDGF (day 3) coincided with the infiltration of inflammatory cells, and the mRNA level of endogenous HDGF correlated with that of tumor necrosis factor α (TNFα). In vitro, TNFα stimulated HDGF expression in endothelial cells. The data suggest that HDGF may be involved in angiogenic responses in the TE chamber and the proinflammatory cytokine TNFα may have a pivotal role in stimulating HDGF expression. Enhancing HDGF signaling may be a new approach to extend vascularization for TE.