Spontaneous immortalization of human dermal microvascular endothelial cells.

Aim: To establish and characterize a spontaneously immortalized human dermal microvascular endothelial cell line, iHDME1.

Methods: We developed a spontaneous immortalization method. This approach is based on the application of optimized culture media and culture conditions without addition of any exogenous oncogenes or carcinogens. Using this approach, we have successfully established a microvascular endothelial cell line, iHDME1, from primary human dermal microvascular endothelial cells. iHDME1 cells have been maintained in culture dishes for more than 50 passages over a period of 6 mo. Using a GFP expressing retrovirus, we generated a GFP-stable cell line (iHDME1-GFP).

Results: iHDME1 retain endothelial morphology and uniformly express endothelial markers such as VEGF receptor 2 and VE-cadherin but not α-smooth muscle actin (α-SM-actin) and cytokeratin 18, markers for smooth muscle cells and epithelial cells respectively. These cells retain endothelial properties, migrate in response to VEGF stimulation and form 3-D vascular structures in Matrigel, similar to the parental cells. There is no significant difference in cell cycle profile between the parental cells and iHDME1 cells. Further analysis indicates enhanced stemness in iHDME1 cells compared to parental cells. iHDME1 cells display elevated expression of CD133 and hTERT.

Conclusion: iHDME1 cells will be a valuable source for studying angiogenesis.