Background
The purpose of this study was to investigate the impact of growth regulators, including growth hormone (GH), insulin-like growth factor 1 (IGF-1), and mechano growth factor (MGF), on endothelial progenitor cell (EPC) proliferation at different glucose concentrations.
Material and Method
EPCs were isolated and cultured from peripheral blood samples of healthy volunteers and immunocytochemically characterized after 7 days. The effects of glucose and growth regulators on EPC proliferation were determined with the Alamar Blue and Trypan Blue assays. The effect of glucose supplementation at 2.5, 11.1, and 25.0 mM was examined using cells seeded at densities of 15000, 30000, and 45000 cells/ml.
Results
For the GH-treated cells, enhancement of EPC proliferation was detected in the samples supplemented with 11.1 and 25.0 mM glucose. A slight elevation in EPC proliferation was only observed in the IGF-1-treated cells supplemented with 25.0 mM glucose. Significant enhancement of EPC proliferation was observed in MGF-treated cells supplemented with 11.1 and 25.0 mM glucose. All three growth factors demonstrated enhancement of cellular proliferation when the cells were supplemented with 25.0 mM glucose. No enhancement of EPC proliferation by the growth factors was detected in any of the cells supplemented with 2.5 mM glucose.
Conclusions
GH, IGF-1, and MGF enhance EPC proliferation under 25.0 mM glucose conditions. The presence of these growth regulators in EPC culture may contribute to protecting EPCs from high-glucose conditions. This action may be of therapeutic relevance contributing to beneficial cardiovascular effects for diabetic patient.

Keywords: Human Growth Hormone - pharmacology, Growth Substances - pharmacology, Glucose - pharmacology, Endothelial Cells - metabolism, Cell Proliferation - drug effects, Adult Stem Cells - metabolism, Insulin-Like Growth Factor I - pharmacology