Non-Invasive In Vivo Detection of Peripheral Limb Ischemia Improvement in the Rat After Adipose Tissue-Derived Stromal Cell Transplantation

Background: Adipose tissue-derived stromal cells (ADSCs) might help repair ischemic cardiovascular tissue. Their in vivo effects on the bioenergetics and microcirculation of ischemic muscle through a variety of non-invasive techniques was examined. Methods and Results: Unilateral hindlimb ischemia was induced in 42 rats. One day after femoral artery ligation, 6 rats per group were randomly injected with intramuscularly allogeneic ADSCs (10-6 10-7 10-8 cells/ml), conditioned media from ADSC cultures (conditioned media [CM], control), saline (control), allogeneic fibroblasts (107cells/ml, control) or a non-conditioned medium (control). Rats underwent magnetic resonance angiography (MRA), short-time inversion recovery (STIR) edema-weighed imaging, proton MR spectroscopy (1H-MRS), thermal infrared imaging (IRI), immunoblotting and immunofluorescence analysis on both hindlimbs for 4 weeks. MRA and STIR documented arterial occlusion and ischemia, respectively. Muscle 1H-MRS and IRI showed reductions of total creatine (tCr)/water and skin temperature in occluded hind limbs, respectively. At 4 weeks, the ADSC and CM groups had greater recovery of skin temperature and tCr/water in ischemic limbs compared with controls (P<0.01), with increased expression of α-sarcomeric actinin and vascular growth factors, such as hepatocyte growth factor (HGF), increased vessel density (capillaries, arterioles and venules) and less type III collagen. Conclusions: Allogeneic ADSCs improve ischemic muscle metabolism, increase neovasculogenesis and decrease fibrosis, largely through a paracrine mechanism. 1H-MRS and IRI are useful tools to monitor attempts at salvaging the ischemic tissues with cell-derived novel therapies.