Erythropoietin, a hypoxia-regulated factor, elicits a pro-angiogenic program in human mesenchymal stem cells.
OBJECTIVE
The ability of erythropoietin (EPO) to elicit a pro-angiogenic effect on human mesenchymal stem cells (hMSC) was tested. hMSC are currently under study as therapeutic delivery agents that target tumor vessels. Hypoxia favors the differentiation of hMSC towards a pro-angiogenic program. However, the classical angiogenic factors, vascular endothelial growth factor and basic fibroblast growth factor, are not fully capable of restoring this effect. The hypoxia-regulated factor, EPO, induces angiogenesis in endothelial cells. Here, EPO's pro-angiogenic effect on hMSC was analyzed.


METHODS
hMSC were tested for EPO receptor expression by western blot, immunofluorescence, and flow cytometry assays. Downstream receptor signaling components JAK and STAT were measured by standard assays. Pro-angiogenesis effects mediated by EPO treatment of hMSC were measured by proliferation, cytokine, or pro-angiogenesis factor secretion, metalloprotease activation, migration, invasion, wound healing, and tubule formation assays.


RESULTS
hMSC express the cognate EPO receptor and are capable of promoting angiogenesis following EPO treatment in all the angiogenesis assays tested. EPO-treated hMSC proliferate and secrete pro-angiogenesis factors more readily than untreated hMSC. EPO leads to increased hMSC chemotaxis, migration, and activation of matrix metalloprotease-2. This treatment causes greater recruitment of vessels as measured in an in vivo angiogenesis assay.


CONCLUSIONS
EPO is capable of eliciting a pro-angiogenesis program in hMSC that instigates secretion of angiogenic factors and the subsequent recruitment of endothelium. This study defines a novel mechanism for tumor cell recruitment of blood vessels that is important to consider in the design of stem cell-based therapies.
Zwezdaryk
Kevin J
KJ
Department of Microbiology & Immunology, Tulane University Health Sciences Center, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
Coffelt
Seth B
SB
Figueroa
Yanira G
YG
Liu
Juliet
J
Phinney
Donald G
DG
LaMarca
Heather L
HL
Florez
Luisa
L
Morris
Cindy B
CB
Hoyle
Gary W
GW
Scandurro
Aline B
AB
D015153:Blotting, Western; D002478:Cells, Cultured; D004921:Erythropoietin / Q000494:pharmacology*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018919:Neovascularization, Physiologic; D017467:Receptors, Erythropoietin / Q000378:metabolism
D017467:Receptors, Erythropoietin; D004921:Erythropoietin