Allogeneic mesenchymal stem cell infusion for treatment of metachromatic leukodystrophy (MLD) and Hurler syndrome (MPS-IH).

Patients with Hurler syndrome (mucopolysaccharidosis type-IH) and metachromatic leukodystrophy (MLD) develop significant skeletal and neurologic defects that limit their survival. Transplantation of allogeneic hematopoietic stem cells results in partial correction of the clinical manifestations. We postulated that some of these defects may be corrected by infusion of allogeneic, multipotential, bone marrow-derived mesenchymal stem cells (MSC). Patients with Hurler syndrome (n = 5) or MLD (n = 6) who previously underwent successful bone marrow transplantation from an HLA-identical sibling were infused with 2-10 x 10(6)/kg MSCs, isolated and expanded from a bone marrow aspirate of the original donor. There was no infusion-related toxicity. In most recipients culture-purified MSCs at 2 days, 30-60 days and 6-24 months after MSC infusion remained of host type. In two patients the bone marrow-derived MSCs contained 0.4 and 2% donor MSCs by FISH 60 days after MSC infusion. In four patients with MLD there were significant improvements in nerve conduction velocities after MSC infusion. The bone mineral density was either maintained or slightly improved in all patients. There was no clinically apparent change in patients' overall health, mental and physical development after MSC infusion. We conclude that donor allogeneic MSC infusion is safe and may be associated with reversal of disease pathophysiology in some tissues. The role of MSCs in the management of Hurler syndrome and MLD should be further evaluated.