Tissue-Engineered Injectable Collagen-Based Matrices for Improved Cell Delivery and Vascularization of Ischemic Tissue Using CD133 + Progenitors Expanded From the Peripheral Blood

Abstract

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.