Stem cell transplantation
SECTION CHIEF Yuko SUZUKI
Skeletal muscle has tissue-specific stem cells named “satellite cells”. Satellite cells exist in a quiescent state between myofibers and the basal lamina. When skeletal muscle is injured, satellite cells are activated, proliferate, and differentiate into myofibers. It is reported that isolated satellite cells/myoblasts from healthy donors are able to fuse with host dystrophin-deficient myofibers after transplantation via intramuscular injection, and expression of dystrophin at the sarcolemma was observed. Therefore, myoblast transfer is expected to be a promising therapy for DMD. However, the numbers of cells prepared from donors are not adequate for clinical use. To obtain a large number of satellite cells/ myoblasts of good quality, we are developing a method to induce muscle stem cells from human iPS cells. Although autologous cell transplantation needs no immunosuppression, the genes require editing to express dystrophin. In addition, the time and expense required for the process impose a burden on patients. As one way to solve the problem, we are trying to use differentiated cells from iPS cell stocks for transplantation. Using stored ready-to-use iPS cells of guaranteed quality and known immune characteristics, such as HLA type, is expected to reduce the cost and time with minimum immune-suppression of the patients. At present, we are pursuing both strategies. We are also participating in a research project utilizing disease-specific iPS cells for rare and refractory muscle diseases to develop pharmaceutical applications.