Tissue-engineered injectable collagen-based matrices for improved cell delivery and vascularization of ischemic tissue using CD133+progenitors expanded from the peripheral blood

Background-The use of stem and/or progenitor cells to achieve potent vasculogenesis in humans has been hindered by low cell numbers, implant capacity, and survival. This study investigated the expansion of CD133(+) cells and the use of an injectable collagen-based tissue engineered matrix to support cell delivery and implantation within target ischemic tissue. Methods and Results-Adult human CD133(+) progenitor cells from the peripheral blood were generated and expanded by successive removal and culture of CD133(-) cell fractions, and delivered within an injectable collagen-based matrix into the ischemic hindlimb of athymic rats. Controls received injections of phosphate-buffered saline, matrix, or CD133(+) cells alone. Immunohistochemistry of hindlimb muscle 2 weeks after treatment revealed that the number of CD133(+) cells retained within the target site was > 2-fold greater when delivered by matrix than when delivered alone (P < 0.01). The transplanted CD133(+) cells incorporated into vascular structures, and the matrix itself also was vascularized. Rats that received matrix and CD133(+) cells demonstrated greater intramuscular arteriole and capillary density than other treatment groups (P < 0.05 and P < 0.01, respectively). Conclusions-Compared with other experimental approaches, treatment of ischemic muscle tissue with generated CD133(+) progenitor cells delivered in an injectable collagen-based matrix significantly improved the restoration of a vascular network. This work demonstrates a novel approach for the expansion and delivery of blood CD133(+) cells with resultant improvement of their implantation and vasculogenic capacity.