Aims: This study observed the relationship of angiogenesis and differential expression of growth factors and their receptors in micro- and macrovascular endothelial cells of diabetic and normal rats.
Main methods: Myocardial microvascular endothelial cells (MMVEC) and aortic endothelial cells (AEC) were isolated from type 2 diabetic-Goto-Kakizaki (GK) rats and age-matched normal Wistar rats. In vitro and in vivo Angiogenesis assay were used to observe the difference between GK rats and Wistar rats. mRNA and protein expression were analyzed by Real-time RT-PCR and Western blotting.
Key findings: MMVEC but not AEC of diabetic rats had reduced abilities of angiogenesis in vitro. Real-time RT-PCR showed increased mRNA levels of VEGF, fms-like tyrosine kinase (Flt-1) and kinase insert domain containing receptor (Flk-1) in GK-MMVEC, but not the hypoxia-inducible factor-1alpha (Hif-1alpha), basic fibroblast growth factor (bFGF), fibroblast growth factor receptor 1 (FGFR1), Angiopoietin-1(Ang-1), Angiopoietin-2(Ang-2), Tie-1 and Tie-2. In contrast, Western blotting showed decreased protein levels of VEGF and receptors, including the phosphorylation of receptors. No significant differences in the expression of theses genes were observed between AEC from diabetic and control rats. Anti-rat VEGF antibodies inhibited MMVEC angiogenic function including cell proliferation, adhesion, migration, scratch wound healing and capillary-like tube formation. The in vivo angiogenesis assay had similar results.
Significance: These result indicated that decreased expression of VEGF and its receptors caused by post-transcription disorder in MMVEC may be responsible for diabetic impaired cardiac angiogenesis.