Scleroderma is an autoimmune, connective tissue disorder which causes fibrosis of the skin and internal organs. In the skin, there is overproduction of extracellular matrix, and type 1 and 3 collagen. The disease involves vascular breakdown where the blood vessels in the skin degenerate and are replaced by collagen to form fibrotic tissue. The sclerotic tissue can also lead to digital ischemia and ulcers. Because of the vasculopathy, there is diminished blood supply to the lesion making the ulcers difficult to heal, prone to infection and progression to gangrene can occur that requires amputation. The ischemic ulcers are frequent, painful, and cause significant morbidity. There are 300,000 people in the US who have scleroderma. There is presently no effective treatment of scleroderma or the ischemic ulcers. Studies by our collaborator, Dr. Vincent Falanga, have shown that one approach that seems effective in healing chronic wounds is through the use of autologous bone marrow (BM) derived stem cells (BMSC). Animal studies showed the BMSCs could effectively heal wounded skin and facilitate production of new blood vessels, and keratinocytes. Autologous BMSCs were also found effective in treating non-healing human chronic wounds in clinical studies. These studies suggest that autologous stem cells in the BM may provide a useful cell based therapy to treat chronic wounds, including digital ischemic ulcers in scleroderma. Studies by NeoStem and its collaborators have shown that within the BM is a resident population of adult, pluripotent stem cells referred to as very small embryonic-like stem cells (VSEL). Animal studies have indicated the potential of VSELs in regenerative medicine by their ability to repair cardiac tissue after myocardial infarct and their ability to reconstitute te immune system after radiation exposure. Adult murine and human VSELs are expressed in BM but can be mobilized to migrate to peripheral blood following G-CSF stimulation where they can be isolated by apheresis and FACS. Consequently, VSELs have potential advantages over use of BMSC in treating chronic wounds because they can be collected in a less invasive manner. In this phase 1 SBIR grant, we propose test the efficacy of VSELs in treating difficult to heal wounds in an animal model of scleroderma the tight skin (Tsk) mouse to establish the potential utility of these cells in treating a debilitating consequences of this disease. The Tsk mouse carries a heterogeneous mutation for the fibrillin-1 gene and rapidly exhibits the characteristic tight and thickened skin phenotype of scleroderma patients. The mice express many symptoms of the scleroderma patient including increases in collagen content in skin as well as immune system dysfunction. The mice have been used extensively to test for potential efficacy of treatments for scleroderma and we propose to employ them to test the potential wound healing capabilities of autologous VSELs in treating difficult to heal skin ulcers in this disease.