The therapeutic potential of ex vivo expanded CD133+ cells derived from human peripheral blood for peripheral nerve injuries

Abstract

CD133(+) cells have the potential to enhance histological and functional recovery from peripheral nerve injury. However, the number of CD133(+) cells safely obtained from human peripheral blood is extremely limited. To address this issue, the authors expanded CD133(+) cells derived from human peripheral blood using the serum-free expansion culture method and transplanted these ex vivo expanded cells into a model of sciatic nerve defect in rats. The purpose of this study was to determine the potential of ex vivo expanded CD133(+) cells to induce or enhance the repair of injured peripheral nerves. Phosphate-buffered saline (PBS group [Group 1]), 10(5) fresh CD133(+) cells (fresh group [Group 2]), 10(5) ex vivo expanded CD133(+) cells (expansion group [Group 3]), or 10(4) fresh CD133(+) cells (low-dose group [Group 4]) embedded in atelocollagen gel were transplanted into a silicone tube that was then used to bridge a 15-mm defect in the sciatic nerve of athymic rats (10 animals per group). At 8 weeks postsurgery, histological and functional evaluations of the regenerated tissues were performed. After 1 week of expansion culture, the number of cells increased 9.6 ± 3.3-fold. Based on the fluorescence-activated cell sorting analysis, it was demonstrated that the initial freshly isolated CD133(+) cell population contained 93.22% ± 0.30% CD133(+) cells and further confirmed that the expanded cells had a purity of 59.02% ± 1.58% CD133(+) cells. However, the histologically and functionally regenerated nerves bridging the defects were recognized in all rats in Groups 2 and 3 and in 6 of 10 rats in Group 4. The nerves did not regenerate to bridge the defect in any of the rats in Group 1. The authors' results show that ex vivo expanded CD133(+) cells derived from human peripheral blood have a therapeutic potential similar to fresh CD133(+) cells for peripheral nerve injuries. The ex vivo procedure that can be used to expand CD133(+) cells without reducing their function represents a novel method for developing cell therapy for nerve defects in a clinical setting.