Human Peripheral Blood-Derived Endothelial Colony-Forming Cells Are Highly Similar to Mature Vascular Endothelial Cells yet Demonstrate a Transitional Transcriptomic Signature

Abstract

Endothelial colony-forming cells (ECFC) are currently considered as a promising cell population for the pre-endothelialization or pre-vascularization of tissue-engineered constructs, including small-diameter biodegradable vascular grafts. However, the extent of heterogeneity between ECFC and mature vascular endothelial cells (EC) is unclear. Here, we performed a transcriptome-wide study to compare gene expression profiles of ECFC, human coronary artery endothelial cells (HCAEC), and human umbilical vein endothelial cells (HUVEC). Characterization of the abovementioned cell populations was carried out by immunophenotyping, tube formation assay, and evaluation of proliferation capability while global gene expression profiling was conducted by means of RNA-seq. ECFC were similar to HUVEC in terms of immunophenotype (CD31 + vWF + KDR + CD146 + CD34 -CD133 -CD45 -CD90 -) and tube formation activity yet had expectedly higher proliferative potential. HCAEC and HUVEC were generally similar to ECFC with regards to their global gene expression profile; nevertheless, ECFC overexpressed specific markers of all endothelial lineages (NRP2, NOTCH4, LYVE1), in particular lymphatic EC (LYVE1), and had upregulated extracellular matrix and basement membrane genes (COL1A1, COL1A2, COL4A1, COL4A2). Proteomic profiling for endothelial lineage markers and angiogenic molecules generally confirmed RNA-seq results, indicating ECFC as an intermediate population between HCAEC and HUVEC. Therefore, gene expression profile and behavior of ECFC suggest their potential to be applied for a pre-endothelialization of bioartificial vascular grafts, whereas in terms of endothelial hierarchy they differ from HCAEC and HUVEC, having a transitional phenotype.

New Technologies With Increased Precision Improve Understanding of Endothelial Cell Heterogeneity in Cardiovascular Health and Disease

“…This indicates the importance of environment on EC gene expression. However, cells do retain some distinguishing factors in vitro, such as intrinsic transcriptional profiles stemming from vascular bed origin and vessel location, which is supportive of a multifactorial process that leads to cell-specific EC transcriptomes (Wick et al, 2007;Burridge and Friedman, 2010;Kutikhin et al, 2020).…”

Therapeutic Potential of Endothelial Colony-Forming Cells in Ischemic Disease: Strategies to Improve their Regenerative Efficacy

“…Recent investigations demonstrated that ECFCs could arise from multiple progenitor cell niches located within the vascular wall of large vessels, including aorta [ 23 ], lung tissue [ 37 ], pulmonary artery [ 38 ], saphenous vein [ 39 ], and placenta [ 40 ], or, they can be obtained from white-adipose tissue [ 41 ] or from human-induced pluripotent stem cells (hiPSCs) sorted for Neuropilin 1 and CD31 [ 42 ]. RNA sequencing confirmed that the gene expression profile of circulating ECFCs was closer to human coronary artery endothelial cells and human umbilical vein endothelial cells as compared to a non-endothelial cell type, such as adipose tissue-derived stromal vascular fraction [ 43 ]. Interestingly, the transcriptomic profile of ECFCs bears more resemblance with that of microvascular, rather than macrovascular, endothelial cells [ 44 ].…”

Molecular Profiling and Gene Banking of Rabbit EPCs Derived from Two Biological Sources

“…The hypothesis, that early rabbit EPCs were analyzed here, can be supported by the expression of slightly different phenotype observed in HUVECs (CD14 − CD29 + CD31 + CD34 − CD49f + CD73 + CD90 +/low CD105 + CD133 − CD146 + VE-cadherin + VEGFR-2 + SSEA-4 − vWF + eNOS + AcLDL + ALDH + ), where markers referred to late EPCs (CD31 and CD146) were detected. Recently was demonstrated that human late EPCs possess similar phenotype (CD31 + CD34 − CD45 − CD90 − CD133 − CD146 + VEGFR-2 + vWF + ) as HUVECs [ 26 ]. Hence, although the flow cytometry or immunofluorescence alone is a standard method for the cell phenotyping, inclusion of other methods such as ddPCR is crucial for discovering the true cell phenotype.…”

“…Altogether, the early EPCs are reported to express progenitor markers as CD34 and CD133 as well as VEGFR-2 (Flk-1/KDR), while the late EPCs lose the expression of CD34 and CD133 and express endothelial-associated markers such as von Willebrand factor (vWF), CD31, VE-cadherin (CD144), endothelial nitric oxide synthase (eNOS), VEGFR-2, CD105 and CD146 [ 3 , 5 , 8 , 13 , 20 , 21 , 22 , 23 , 24 , 25 ]. Moreover, the recent study [ 26 ] demonstrated that late EPCs possess similar phenotype (CD31 + vWF + KDR + CD146 + CD34 − CD133 − CD45 − CD90 − ) as human umbilical vein endothelial cells (HUVECs). Interestingly, a transdifferentiation of HUVECs into neuron-like cells was observed under certain culture conditions [ 27 , 28 , 29 ], although there is no information about such differentiation potential of EPCs.…”