- Loss of potency and difficulty in scaling up ex vivo expansion- Poor cell engraftment and survival- Not suitable for systemic transplantation due to limited cell migration (stays at the injection site)- Little restoration of dystrophin expression due to inefficient fusion- Difficulty in targeting the diaphragm and heart- Limited effects due to dystrophic muscle associated with fat and fibrotic infiltrations in severe fibrosis in progressed DMD.- Immune rejection. The gene discussed is DMD; the disease is Duchenne muscular dystrophy.