Dystrophin expression in muscles of duchenne muscular dystrophy patients after high-density injections of normal myogenic cells.

A clinical trial was conducted to test a new protocol of normal muscle precursor cell (MPC) allotransplantation in skeletal muscles of patients with Duchenne muscular dystrophy (DMD). Cultured MPCs obtained from one of the patient's parents were implanted in 0.25 or 1 cm of a Tibialis anterior in 9 patients with DMD. MPC injections were placed 1 to 2 mm from each other, and a similar pattern of saline injections was done in the contralateral muscle. The patients were immunosuppressed with tacrolimus. Muscle biopsies were performed at the injected sites 4 weeks later. In the biopsies of the cell-grafted sites, there were myofibers expressing donor's dystrophin in 8 patients. The percentage of myofibers expressing donor's dystrophin varied from 3.5% to 26%. Evidence of small myofiber neoformation was observed in some patients. Donor-derived dystrophin transcripts were detected by reverse transcriptase-polymerase chain reaction in the cell-grafted sites in all patients. The protocol of immunosuppression was sufficient to obtain these results, although it is not certain whether acute rejection was efficiently controlled in all the cases. In conclusion, intramuscular allotransplantation of normal MPCs can induce the expression of donor-derived dystrophin in skeletal muscles of patients with DMD, although this expression is restricted to the sites of MPC injection.

Dystrophin expression in myofibers of Duchenne muscular dystrophy patients following intramuscular injections of normal myogenic cells.

Three Duchenne muscular dystrophy (DMD) patients received injections of myogenic cells obtained from skeletal muscle biopsies of normal donors. The cells (30 x 10 (6)) were injected in 1 cm3 of the tibialis anterior by 25 parallel injections. We performed similar patterns of saline injections in the contralateral muscles as controls. The patients received tacrolimus for immunosuppression. Muscle biopsies were performed at the injected sites 4 weeks later. We observed dystrophin-positive myofibers in the cell-grafted sites amounting to 9 (patient 1), 6.8 (patient 2), and 11% (patient 3). Since patients 1 and 2 had identified dystrophin-gene deletions these results were obtained using monoclonal antibodies specific to epitopes coded by the deleted exons. Donor dystrophin was absent in the control sites. Patient 3 had exon duplication and thus specific donor-dystrophin detection was not possible. However, there were fourfold more dystrophin-positive myofibers in the cell-grafted than in the control site. Donor-dystrophin transcripts were detected by RT-PCR (using primers reacting with a sequence int eh deleted exons) only in the cell-grafted sites in patients 1 and 2. Dystrophin transcripts were more abundant in the cell-grafted than in the control site in patient 3. Therefore, significant dystrophin expression can be obtained in teh skeletal muscles of DMD patients following specific conditions of cell delivery and immunosuppression.