Predicting Angiogenesis by Endothelial Progenitor Cells Relying on In-Vitro Function Assays and VEGFR-2 Expression Levels

Abstract

Clinical trials have demonstrated the safety and efficacy of autologous endothelial progenitor cell (EPC) therapy in various diseases. Since EPCs’ functions are influenced by genetic, systemic and environmental factors, the therapeutic potential of each individual EPCs is unknown and may affect treatment outcome. Therefore, our aim was to compare EPCs function among healthy donors in order to predict blood vessel formation (angiogenesis) before autologous EPC transplantation. Human EPCs were isolated from the blood of ten volunteers. EPCs proliferation rate, chemoattractant ability, and CXCR4 mRNA levels were different among donors (p < 0.0001, p < 0.01, p < 0.001, respectively). A positive correlation was found between SDF-1, CXCR4, and EPCs proliferation (R = 0.736, p < 0.05 and R = 0.8, p < 0.01, respectively). In-vivo, blood vessels were counted ten days after EPCs transplantation in a subcutaneous mouse model. Mean vessel density was different among donors (p = 0.0001); nevertheless, donors with the lowest vessel densities were higher compared to control (p < 0.05). Finally, using a linear regression model, a mathematical equation was generated to predict blood vessel density relying on: (i) EPCs chemoattractivity, and (ii) VEGFR-2 mRNA levels. Results reveal differences in EPCs functions among healthy individuals, emphasizing the need for a potency assay to pave the way for standardized research and clinical use of human EPCs.

The Paracrine Role of Endothelial Cells in Bone Formation via CXCR4/SDF-1 Pathway

“…Shortly after, musculoskeletal traumatic event EPCs were mobilized into the circulation, therefore their levels are higher [38]. Alterations in EPCs genotype and phenotype after bone trauma were not studied, however it is possible to find slight changes in the cells between unrelated donors [23].…”

“…To understand the molecular mechanism behind this paracrine effect, quantitative real-time PCR analysis for 96 angiogenic genes was performed on EPC, that revealed high mRNA levels of angiogenic factors including: FGF, KDR/VEGFR, CXCL12/SDF-1, and osteogenic factors, such as: PDGF and BMP-4. In a previous study [23] we analyzed the mRNA expression of angiogenic and chemoattractant genes (SDF-1, VEGF-A, CCL2, PDGFB, VEGFR-2 and CXCR4 genes) in primary human EPCs isolated from ten unrelated donors. We found differences in RQ values between the donors, as can be expected for primary cells, and positive correlations between SDF-1 and CXCR4.…”

“…Early EPCs were positive for CD31, CD45, VEGFR-2 and CD14. Late EPCs were positive for: CD31, CD34 and negative for CD14 and CD45 [23].…”

Stem cell‐based therapies for cardiac diseases: The critical role of angiogenic exosomes

“…80 EPCs have shown a great tendency to differentiate into mature ECs; hence, they are considered suitable candidates for inducing angiogenesis. 81 It has been well-documented that EPCs can form vascular structures that showed permeability values close to the vessel-derived endothelium. [82][83][84] EPCs are supposed to home to ischemic sites (e.g., infarcted myocardium) and contribute to forming a structural component of capillaries.…”

Review of Integrin‐Targeting Biomaterials in Tissue Engineering

“…[346] This observation may also extend to MSCs involved in regenerative capacities for other processes like wound healing and cardiovascular applications. [347,348] To the best of our knowledge, researchers have yet to publish studies evaluating effects of donor variability on migration or proliferative capabilities for other cell types like fibroblasts or endothelial cells. Regardless, this should be accounted for when evaluating the bioinstructive capabilities of integrin-targeted materials by observing cell-material interactions from cultures isolated from different donors to confirm trends with added rigor.…”