Culture and Characterization of Circulating Endothelial Progenitor Cells in Patients with Renal Cell Carcinoma

Purpose: Although emerging evidence demonstrates increased circulating endothelial progenitor cells in patients with solid tumors, to our knowledge it is still unknown whether such cells can be cultured from patients with highly angiogenic renal cell carcinoma. We cultured and characterized circulating endothelial progenitor cells from patients with renal cell carcinoma. Materials and Methods: The circulating endothelial progenitor cell level (percent of CD45(-) CD34(+) VEGF-R2(+) cells in total peripheral blood mononuclear cells) was quantified in 47 patients with renal cell carcinoma and 40 healthy controls. Peripheral blood mononuclear cells were then isolated from 33 patients with renal cell carcinoma and 30 healthy controls to culture and characterize circulating endothelial progenitor cells. Results: The circulating endothelial progenitor cell level was significantly higher in patients with renal cell carcinoma than in healthy controls (0.276% vs 0.086%, p < 0.001). A colony of circulating endothelial progenitor cells first emerged significantly earlier in patient than in control preparations (6.72 vs 14.67 days, p < 0.001). The culture success rate (87.8% vs 40.0% of participants) and the number of colonies (10.06 vs 1.83) were significantly greater for patients than for controls (each p < 0.001). The circulating endothelial progenitor cell level correlated positively with the number of patient colonies (r = 0.762, p <0.001). Cells cultured from patients and controls showed a similar growth pattern, immunophenotype, ability to uptake Ac-LDL and bind lectin, and form capillary tubes in vitro. However, significantly more VEGF-R2(+) circulating endothelial progenitor cells were found in preparations from patients with renal cell carcinoma than from healthy controls (21.1% vs 13.4%, p < 0.001). Conclusions: Earlier emergence of circulating endothelial progenitor cell colonies, a higher cell culture success rate and more colonies were found for patients with renal cell carcinoma than for healthy controls. Results indicate the important significance of VEGF-R2(+) circulating endothelial progenitors in patients with renal cell carcinoma.