FIG. 5.
The effect of HGF/c-Met signaling on MSC tissue repair capacity in a hindlimb ischemia injury model. (a) Hindlimb ischemia surgeries were performed on immunodeficient NOD/SCID mice, followed by intraperitoneal injection of anti-CD122 antibody. Approximately 24 h after the surgery, the mice were injected intramuscularly with 106 human BMSC that had been cultured at 3% oxygen or 21% oxygen. The blood flow recovery to the ischemic limb was followed by laser Doppler perfusion imaging for 2 weeks after the surgery. (b) The laser Doppler perfusion imaging results demonstrate that the mice injected with hypoxia-preconditioned MSC recovered significantly better than the saline controls (two-way ANOVA), whereas there was no significant difference between the control group and the group injected with MSC cultured in 21% oxygen (two-way ANOVA). On the basis of these results, the MSC used in our next hindlimb ischemia experiment were all preconditioned at 1%–3% oxygen before the transplantation. (c) Mice injected with SCR MSC were able to improve blood flow recovery after hindlimb ischemia to the same degree as nontransduced MSC; both SCR- and nontransduced MSC restored blood flow significantly faster than the saline controls (two-way ANOVA). The blood flow recovery in mice transplanted with 4246 KD MSC (70% KD of c-Met) was significantly slower than that in the SCR MSC group (two-way ANOVA). (d) The blood flow recovery of animals treated with 4571 KD MSC (60% c-Met KD) was not significantly different from those treated with SCR MSC. The summarized data are based on seven (b, hypoxic and PBS groups) and eight (b, normoxic) animals per group. The graphs shown in (c) and (d) belong to the same experiment and are only separated to improve clarity. Therefore, these data can be directly compared to each other, and the SCR MSC and PBS curves are identical in both graphs. The data are representative of 12 (4246), 14 (untransduced MSC and SCR MSC), and 15 (PBS and 4571) animals per group. *Signifies p < 0.05 compared with saline-treated mice. NS, not significant. PBS, phosphate-buffered saline. Color images available online at www.liebertonline.com/ten.