[Treatment progress of Duchenne Muscular Dystrophy (DMD)]

Duchenne muscular dystrophy (DMD) is a common lethal disease for which no effective treatment is currently available. There exists a mouse model of the disease in which the usefulness of gene therapy was established. However, no progress towards human application was made due to the lack of a proper method for gene delivery. During the past several years, researchers acquired data which led them to believe that bone marrow stem cells are capable of generating not only blood cells, but also liver, heart, skin, muscle, and other tissue. Although the term "stem cell plasticity" became very popular, other studies have suggested that bone marrow might contain different types of stem cells that can produce non-hematopoietic cells. For example, mesenchymal stem cell (MSC) in bone marrow give rise to osteocytes, chondrocytes, adipocytes, and skeletal muscle. Recently, researchers have been able to show that transplanted bone marrow cells can contribute to muscle cells in a human patient who was diagnosed with two genetic diseases: severe combined immunodeficiency (SCID) and Duchenne muscular dystrophy. The odds of this happening is estimated at one in seven million. The results of studying this patient's medical history were reported by collaborating researchers at Children's Hospital, Los Angeles and Children's Hospital, Boston in an article titled "Long-term persistence of donor nuclei in a Duchenne muscular dystrophy (DMD) patient receiving bone marrow transplantation" published in the September 2002 issue of the Journal of Clinical Investigation. This patient was transplanted 15 years ago at Children's Hospital Los Angeles with paternal HLA-haploidentical T cell-depleted bone marrow. He engrafted and became a hematopoietic chimera having T and NK lymphocytes of donor origin. Studies performed on the muscle biopsy from the patient 13 years after transplantation demonstrated that the muscle showed evidence of donor derived nuclei. In addition, analysis of his bone marrow showed that small numbers of MSC were also derived from the transplanted bone marrow. Unfortunately, there was no evidence that the number of new muscle cells from the donor was able to decrease the progression of his muscular dystrophy. The revelation of finding the donor's cells in the muscle of the patient provides new hope for patients with the same disease. In the future it may be possible for mesenchymal cells to be isolated, ex vivo expanded and transplanted into patients with muscle diseases.