Pretreatment of endothelial progenitor cells with osteopontin enhances cell therapy for peripheral vascular disease.
Tissue necrosis resulting from critical limb ischemia (CLI) leads to amputation in a significant number of patients. Autologous cell therapy using angiogenic cells such as endothelial progenitor cells (EPCs) holds promise as a treatment for CLI but a limitation of this treatment is  that the underlying disease etiology that resulted in CLI may also contribute to dysfunction of the therapeutic EPCs. This study aimed to elucidate the mechanism of EPC dysfunction using diabetes mellitus as a model and to determine whether correction of this defect in dysfunctional EPCs ex  vivo would improve the outcome after cell transplantation in the murine hind limb ischemia model. EPC dysfunction was confirmed in a homogenous population of patients with type 1 diabetes mellitus and a microarray study was preformed to identify dysregulated genes. Notably, the secreted proangiogenic  protein osteopontin (OPN) was significantly downregulated in diabetic EPCs. Furthermore, OPN-deficient mice showed impaired recovery following hind limb ischemia, suggesting a critical role for OPN in postnatal neovascularization. EPCs isolated from OPN KO mice showed decreased ability to  adhere to endothelial cells as well as impaired angiogenic potential. However, this dysfunction was reversed upon exposure to recombinant OPN, suggesting that OPN may act in an autocrine manner on EPCs. Indeed, exposure of OPN knockout (KO) EPCs to OPN was sufficient to induce the secretion  of angiogenic proteins (IL-6, TGF-α, and FGF-α). We also demonstrated that vascular regeneration following hind limb ischemia in OPN KO mice was significantly improved upon injection of EPCs preexposed to OPN. We concluded that OPN acts in an autocrine manner on EPCs to induce  the secretion of angiogenic proteins, thereby playing a critical role in EPC-mediated neovascularization. Modification of cells by exposure to OPN may improve the efficacy of autologous EPC transplantation via the enhanced secretion of angiogenic proteins.
Regenerative Medicine Institute (REMEDI), National Centre for Biomedical Engineering Science (NCBES), National University Ireland Galway (NUIG), Galway, Ireland.
E E
EE
Vaughan
A
A
Liew
K
K
Mashayekhi
P
P
Dockery
J
J
McDermott
B
B
Kealy
A
A
Flynn
A
A
Duffy
C
C
Coleman
A
A
O'Regan
F P
FP
Barry
T
T
O'Brien
D000328:Adult; D000818:Animals; D064987:Cell- and Tissue-Based Therapy; D002478:Cells, Cultured; D003922:Diabetes Mellitus, Type 1 / Q000473:pathology; D042783:Endothelial Cells / Q000166:cytology*; D005260:Female; D005346:Fibroblast Growth Factors / Q000378:metabolism; D006614:Hindlimb / Q000098:blood supply; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D007511:Ischemia / Q000378:metabolism / Q000628:therapy; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic / Q000187:drug effects; D053495:Osteopontin / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D016491:Peripheral Vascular Diseases / Q000378:metabolism / Q000628:therapy*; D011817:Rabbits; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D012038:Regeneration; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016211:Transforming Growth Factor alpha / Q000378:metabolism; D055815:Young Adult
D015850:Interleukin-6; D011994:Recombinant Proteins; D016211:Transforming Growth Factor alpha; D053495:Osteopontin; D005346:Fibroblast Growth Factors