VEGFA and diabetes mellitus: The mRNA expression level of both VEGF and Ang-1 was lower in the diabetic group than in the nondiabetic group (Additional file 4: Figure S4; VEGF, 722.9 ± 140.6 in non-DM vs 390.7 ± 121.3 in DM; Ang-1, 365.8 ± 135.6 in non-DM vs 106.8 ± 13.9 in DM; P < 0.05), indicating a lack of proangiogenic factors in the diabetic microenvironment.