Magnetic resonance spectroscopy to detect functional improvement by adipose tissue-derived stromal cell transplantation in the ischemic hind limb in diabetic rats

Adipose tissue-derived stromal cells (ADSCs) are a prominent cellular source in regenerative medicine. We tested whether transplantation of ADSCs into ischemic muscular tissue of diabetic animals would attenuate the impairment in cell metabolism and microcirculatory with a combination of techniques including magnetic resonance imaging and spectroscopy (1H-MRS). Methods: We induced unilateral hind limb ischemia in male streptozotocin-treated rats and non-diabetic controls. One day after femoral artery ligation, 6 rats per group were randomly injected intramuscularly allogeneic ADSCs (C1: 106, C2: 107, C3: 108 cells/mL); or conditioned media from ADSC cultures (CM); or saline (control). Rats underwent magnetic resonance angiography (MRA); short time inversion recovery (STIR) edema-weighed imaging; 1H-MRS; immunoblotting and immunofluorescence on both hind limbs for 4 weeks. Results: T1-weighted and STIR images showed the presence of tissue swelling and signal hyperintensity respectively in tissue affected by occlusion. Mean total ratio of tissue creatine/water (tCr/water) for the occluded limb was significantly lower than for the non-occluded limbs in both non-diabetic and diabetic rats. At 4 weeks, ADSC and CM groups had greater recovery of tCr/water in ischemic limbs compared with controls in both diabetic- and non-diabetic rats (**p<0.01; *p<0.05) (Figure 1, panel A), with less tissue swelling (panel B), increased expression of α-sarcomeric actinin, vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) (Table 1), as well as increased vessel density (panel C) and suppression of the up-regulation of water channel aquaporin (AQP)-1 and pro-inflammatory early response gene such as cycloxygenase (COX)-2 (panel D). ![Figure][1] Figure 1 View this table: Table 1. VEGF and HGF expression in diabetic rat ischemic tissues after femoral artery ligation and treatments with ADSCs conditioned medium and controls Conclusions: ADSCs improve ischemic muscle metabolism and increase neovasculogenesis in diabetic rats with hind limb ischemia. 1H-MRS is a useful tool to monitor attempts at salvaging the ischemic tissues with cell-derived novel therapies. [1]: pending:yes