Abstract: Methods of stimulating muscle regeneration, comprising delivering to a muscle a CCR5 interacting agent or encoding molecule. The CCR5 interacting agent binds to muscle stem cells and stimulates myoblast proliferation and muscle regeneration. One example of the CCR5 interacting agent is NAMPT comprising a cytokine finger motif or a derivative thereof. Methods and compositions include cellular compositions, which expresses the CCR5 interacting agent; including a population of satellite or macrophage cells or their precursors/progeny and their applications in stem cell therapy or for use in treating a muscular deficiency, disorder or injury. The examples show muscle tissue regeneration with minimal fibrosis. Also enabled is a NAMPT polypeptide fragment comprising a C-terminal portion of NAMPT comprising a cytokine finger.