SCID mice ability to accept grafts ksengenicznch, allows the study of human stem cells share tissue regeneration. Regeneration of skeletal muscle is a good model for the study of stem cell involvement in the process. Regeneration of skeletal muscles depends on the presence of satellite cells (muscle precursor cells). Apart from them can participate in the regeneration of stem cells from other tissues. The aim of the project is to investigate what might be involved in the regeneration of stem cells in a xenograft system.