Human umbilical cord blood cells differentiate into muscle in sjl muscular dystrophy mice

Limb girdle muscular dystrophy type 2B form (LGMD-2B) and Miyoshi myopathy (MM) are both caused by mutations in the dysferlin (dysf) gene. In this study, we used dysferlin-deficient sjl mice as a mouse model to study cell therapy for LGMD-2B and MM. A single-blind study evaluated the therapeutic potential of human umbilical cord blood (HUCB) as a source of myogenic progenitor stem cells. Three groups of donor cells were used: unfractionated mononuclear HUCB cells, HUCB subfractionated to enrich for cells that were negative for lineage surface markers (LIN^-) and substantially enriched for the CD34 surface marker (CD34⁺), and irradiated control spleen cells. We administrated 1 × 10⁶ donor cells to each animal intravenously and euthanized them at different time points (1-12 weeks) after transplantation. All animals were immunosuppressed (FK506 and leflunomide) from the day before the injection until the time of euthanasia. Immunohistochemical analyses documented that a small number of human cells from the whole HUCB and LIN-CD34^+/-- enriched HUCB subgroups engraft in the recipient muscle to express both dysferlin and human-specific dystrophin at 12 weeks after transplantation. We conclude that myogenic progenitor cells are present in the HUCB, that they can disseminate into muscle after intravenous administration, and that they are capable of myogenic differentiation in host muscle.