Transient Inhibition of Transforming Growth Factor-beta1 in Human Diabetic CD 34+ Cells Enhances Vascular Reparative Functions

Objective: Peripheral blood CD34(+) cells from diabetic patients demonstrate reduced vascular reparative function due to decreased proliferation and diminished migratory prowess, largely resulting from decreased nitric oxide (NO) bioavailability. The levels of TGF-beta, a key factor that modulates stem cell quiescence, are increased in the serum of type 2 diabetics. We asked whether transient TGF-beta1 inhibition in CD34(+) cells would improve their reparative ability. Research Design and Methods: To inhibit TGF-beta1 protein expression, CD34(+) cells were treated ex vivo with antisense phosphorodiamidate morpholino oligomers (TGF-beta1-PMO) and analyzed for cell-surface CXCR4 expression, cell survival in the absence of added growth factors, SDF-1-induced migration, NO release, and in vivo retinal vascular reparative ability. Results: TGF-beta1-PMO treatment of diabetic CD34(+) cells resulted in increased expression of CXCR4, enhanced survival in the absence of growth factors, and increased migration and NO release as compared to cells treated with control PMO. Using a retinal ischemia reperfusion injury model in mice, we observed that recruitment of diabetic CD34(+) cells to injured acellular retinal capillaries was greater following TGF-beta1-PMO treatment compared to control-PMO treated cells. Conclusion: Transient inhibition of TGF-beta1 may represent a promising therapeutic strategy for restoring the reparative capacity of dysfunctional diabetic CD34(+) cells.