Allogenic Vertebral Body Adherent Mesenchymal Stromal Cells Promote Muscle Recovery in Diabetic Mouse Model of Limb Ischemia.

BACKGROUND

Chronic limb-threatening ischemia (CLTI) carries a significant risk for amputation, especially in diabetic patients with poor options for revascularization. Phase I trials have demonstrated efficacy of allogeneic mesenchymal stromal cells (MSC) in treating diabetic CLTI. Vertebral bone-adherent mesenchymal stromal cells (vBA-MSC) are derived from vertebral bodies of deceased organ donors, which offer the distinct advantage of providing a 1,000x greater yield compared to that of living donor bone aspiration. This study describes the effects of intramuscular injection of allogenic vBA-MSC in promoting limb perfusion and muscle recovery in a diabetic CLTI mouse model.

METHODS

A CLTI mouse model was created through unilateral ligation of the femoral artery in male polygenic diabetic TALLYHO mice. The treated mice were injected with vBA-MSC into the gracilis muscle of the ischemic limb 7 days post ligation. Gastrocnemius or tibialis muscle was assessed postmortem for fibrosis by collagen staining, capillary density via immunohistochemistry, and mRNA by quantitative real-time polymerase chain reaction (PCR). Laser Doppler perfusion imaging and plantar flexion muscle testing (MT) were performed to quantify changes in limb perfusion and muscle function.

RESULTS

Compared to vehicle (Veh) control, treated mice demonstrated indicators of muscle recovery, including decreased fibrosis, increased perfusion, muscle torque, and angiogenesis. PCR analysis of muscle obtained 7 and 30 days post vBA-MSC injection showed an upregulation in the expression of MyoD1 (P = 0.03) and MyH3 (P = 0.008) mRNA, representing muscle regeneration, vascular endothelial growth factor A (VEGF-A) (P = 0.002; P = 0.004) signifying angiogenesis as well as interleukin (IL-10) (P < 0.001), T regulatory cell marker Foxp3 (P = 0.04), and M2-biased macrophage marker Mrc1 (CD206) (P = 0.02).

CONCLUSIONS

These findings indicate human allogeneic vBA-MSC ameliorate ischemic muscle damage and rescue muscle function. These results in a murine model will enable further studies to develop potential therapies for diabetic CLTI patients.