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

Abstract

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. 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 (10(7) cells/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 ((1)H-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 (1)H-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. Allogeneic ADSCs improve ischemic muscle metabolism, increase neovasculogenesis and decrease fibrosis, largely through a paracrine mechanism. (1)H-MRS and IRI are useful tools to monitor attempts at salvaging the ischemic tissues with cell-derived novel therapies.