Figure 1.

Transplantation of genetically corrected cells requires engraftment into the satellite cell compartment. Since myogenic precursors fuse with damaged myofibers to form a single syncytium, establishing a genetically-corrected stem cell compartment will lead to the long-term replacement of diseased tissue. A: Cross-section through the TA muscle showing GFP+ satellite cells (arrows) and myofibers. A′: A GFP+ satellite cell is observed on a single GFP− myofiber. In this case, GFP+ satellite cells will participate in future remodeling of muscle tissue and incorporate genetic corrections into host myofibers making them GFP+ as well. A graft of committed progenitors rather leads to excessive differentiation and will marginally engraft into the stem cell compartment. B: GFP is only found in myofibers but not satellite cells. B′: Micrograph of a GFP+ myofiber which is derived from GFP+ satellite cells that differentiated. Note that all fiber associated cells are GFP−. Although the establishment of genetically-corrected myofibers is the ultimate goal, without a stem cell population, the effects of these transplants are likely to diminish due to tissue turnover. C: Cartoon schematic of the possible long-term transplantation outcomes described above.