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.
Highlights
In order to maintain homeostasis, tissues of multicellular organisms are endowed with a vascular system responsible for gas and nutrient exchange
We had previously demonstrated the following: 1) early growth response factor (Egr)-3 expression was highly promoted when human UCBMSCs differentiated towards the endothelial cell (EC) lineage; 2) in Matrigel, similar to mature ECs such as human umbilical vein ECs (HUVECs), UCBMSCs had the ability to rapidly migrate developing well-organized vascular-like networks; and 3) developed networks showed high amounts of Egr-3 within the nuclei of aligned cells [18]
In accordance with this background, we further investigated the molecular machinery regulating the angiogenic behaviour of UCBMSCs and whether Egr-3 was mechanistically involved
Summary
In order to maintain homeostasis, tissues of multicellular organisms are endowed with a vascular system responsible for gas and nutrient exchange. Maintenance of this paramount function is dependent on endothelium integrity. Whereas the endothelium used to be considered a simple inert barrier between blood vessels and subjacent tissues, it is recognized as a specialized layer of cells - endothelial cells (ECs) - [1]. It is clear that ECs have critical roles in organism homeostasis and in moving nutrients, gases and waste products to and from cells [2,3,4]. Loss of vascular endothelial homeostasis critically contributes to the origin and/or progression of numerous ischemic, inflammatory, infectious and immune diseases in humans [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
