Human embryonic stem cells (hESCs) are promising in regenerative medicine (RM) due to their differentiation plasticity and proliferation potential. However, a major challenge in RM is the generation of a vascular system to support nutrient flow to newly synthesized tissues. Here we refined an existing method to generate tight vessels by differentiating hESCs in CD34(+) vascular progenitor cells using chemically defined media and growth conditions. We selectively purified these cells from CD34(-) outgrowth populations also formed. To analyze these differentiation processes, we compared the proteomes of the hESCs with those of the CD34(+) and CD34(-) populations using high resolution mass spectrometry, label-free quantification, and multivariate analysis. Eighteen protein markers validate the differentiated phenotypes in immunological assays; nine of these were also detected by proteomics and show statistically significant differential abundance. Another 225 proteins show differential abundance between the three cell types. Sixty-three of these have known functions in CD34(+) and CD34(-) cells. CD34(+) cells synthesize proteins implicated in endothelial cell differentiation and smooth muscle formation, which support the bipotent phenotype of these progenitor cells. CD34(-) cells are more heterogeneous synthesizing muscular/osteogenic/chondrogenic/adipogenic lineage markers. The remaining >150 differentially abundant proteins in CD34(+) or CD34(-) cells raise testable hypotheses for future studies to probe vascular morphogenesis.
Keywords: CD34+; PLS; angiogenesis; comparative proteomics; endothelial progenitor cells; hESCs; multivariate analysis; vascular cell differentiation.