In Vitro Characterization of the Molecular Machinery Regulating Umbilical Cord Blood Mesenchymal Stem Cell Angiogenesis: A Step Towards Multipotent Stem Cell Therapy for Vascular Regeneration

Abstract

Umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) promote vascular growth in vivo. Here we examined the intracellular regulatory machinery involved in the in vitro angiogenic behaviour exhibited by UCBMSCs. Angiogenic activity was measuring in the standard Matrigel-based culture assay after treatment of cells with known modulators of early growth response factor (Egr-3) and endothelial cell (EC) angiogenesis. Egr-3 expression was assessed by quantitative RT-PCR and indirect immunofluorescence, and specifically abrogated using small interfering RNA (siRNA) technology. While addition of phorbol-12-myristate-13-acetate (PMA) promoted angiogenic capacity (P<0.001), selective inhibitors of PKC/MAPK/ERK abrogated this capacity (P=0.016) in UCBMSCs. Treatment with PMA increased Egr-3 mRNA and protein levels (P<0.001). However, cyclosporine A (CsA) and vascular endothelial growth factor (VEGF) affected neither Egr-3 levels nor the formation of polygonal cell networks. PMA also induced ERK1/2 phosphorylation, which was abolished by the selective inhibitor U0126 (P=0.021 and P=0.014, respectively). Marked inhibition of network-forming capacity was observed in siEgr-3-transduced cells (P<0.001). Taken together, our results highlight that Egr-3 is commonly involved in the molecular machinery regulating mature EC and multipotent MSC angiogenesis. This knowledge may be applied to increase therapeutic efficacy against human vascular diseases.

Therapeutic Use of Stem Cells for Myocardial Infarction

“…Although previously used mainly in the treatment of hematological conditions, uses have expanded to effectively treat non-hematopoietic conditions as well [ 46 ]. Umbilical cord blood mesenchymal stem cells (UCBMSCs) comprise one of the non-hematopoietic stem cell populations in UCB, and although cells have failed to successfully differentiate into cardiac lineages, studies have demonstrated their role in angiogenesis and immunogenicity (as with other MSC populations) [ 69 ].…”

Mesenchymal stem cells for cardiac repair: are the actors ready for the clinical scenario?

“…In past years, studies have exposed UCBMSCs to a myriad of cardiomyogenic stimuli and failed to achieve transdifferentiation to a cardiac lineage [ 34 ]. Nevertheless, through those studies, UCBMSCs have garnered a great deal of attention, which stimulated studies on the molecular mechanisms involved in regulating angiogenesis [ 35 ], the induction of vascular growth in vivo [ 36 ], and methods for preclinically predicting the immunogenicity of prospective stem cells [ 27 ]. For instance, although direct contact with neonatal rat cardiomyocytes could effectively induce a cardiomyocyte-like phenotype in cATMSCs [ 22 ], it did not promote the expression of cardiomyocyte-specific proteins, rhythmic calcium oscillations, or potential-dependent fluorescence emissions in these cells [ 34 ].…”