Abstract 1304: Bone Marrow-derived CXCR4+ Cells as a New Source for Therapeutic Angiogenesis
Background: Therapeutic angiogenesis using bone marrow cells (BMC) in patients with severe ischemic limbs has been successfully performed; however, more efficient strategy is needed. Because the chemokine stromal cell-derived factor-1 (SDF-1) and its receptor CXCR4 play an essential role in homing of BMC to the site of ischemia, we examined whether CXCR4+ BMC could effectively stimulate angiogenesis in a murine model of hindlimb ischemia.
Methods and Results: We found that expression of CXCR4 was upregulated by cultivation, but not CCR7, L-selectin, CD34, CD31, Flk-1, Sca-1, c-kit, Gr-1, CD3, and CD11b, in BMC; therefore we used freshly isolated BMC and cultured BMC as CXCR4low and CXCR4high, respectively. In vitro experiments showed that migration activity of CXCR4high in response to SDF-1 was significantly increased than that of CXCR4low. After 1 day from the ischemia induction in nude mice, CXCR4low, CXCR4high or PBS (control) was injected into the ischemic limb. Immunohistochem-istry revealed that SDF-1 was expressed by hindlimb ischemia, and capillary density, assessed by CD31 and VE-cadherin, was significantly increased in the ischemic sites of CXCR4high-injected mice, compared with those of control and CXCR4low-injected mice (p<0.05). Laser Doppler perfusion imaging showed that the blood flow of the ischemic hindlimb (ischemic/ non-ischemic ratio) at 21 days after the induction was higher in CXCR4high-injected mice than that in control and CXCR4low-injected mice (control: 0.54±0.14, CXCR4low: 0.58±0.19, CXCR4high: 0.80±0.11, p<0.05). Flow cytometry analysis showed that the number of BMC (prepared from GFP mice) in the injected-site at 1 day after the injection was greater in CXCR4high-injected mice than that in CXCR4low-injected mice (p<0.05); however, both CXCR4high and CXCR4low completely disappeared from the injected-site at 21 days after the injection. In addition, the mRNA expression of IL-1β and VEGF-A in the ischemic limb of CXCR4high-injected mice was increased compared with that of CXCR4low-injected mice.
Conclusions: These findings suggest that bone marrow-derived CXCR4+ cells improve hindlimb ischemia and are a promising source for therapeutic angiogenesis in the treatment of ischemic cardiovascular diseases.