Reduced Intensity Conditioning Hematopoietic Stem Cell Transplantation (HSCT) with Mesenchymal Stem Cells (MSC) Infusion for Treatment of Metachromatic Leukodystrophy (MLD): A Case Report.

Background: Patients (pts) with MLD have neurological and musculo-skeletal defects with a limited survival. HSCT has been reported as an effective treatment to stabilize or improve defects associated with this disease. Koç and colleagues reported that donor allogeneic MSC infusion is safe and may be associated with reversal of the disease pathophysiology in some tissues (Bone Marrow transplant, 2002). We decide thus to perform a non myeloablative familial HSCT in adult pt with a symptomatic MLD in order to evaluate the safety and the benefit allogeneic HSCT with MSC infusion in a patient with MLD. An informed consent was obtained from the pt.

Patient: a 23 years old women who presented an adult form of MLD for three years was admitted in our department. The most important symptoms associated with the disease were dizziness, proximal weakness of the lower limbs, difficulty to walk, disorder of the memory and urinary incontinence. The reduced intensity conditioning was preferred to decrease the morbidity and mortality of the procedure. MSC were isolated and amplified from the BM-mononuclear cells of the HSC donor. MSC expansion was made in a commercial serum-free medium (UltraCulture, Cambrex, Walkersville, MD) supplemented with a serum substitute (Ultroser, Pall Biosepra, Cergy-Saint-Christophe, France) as previously reported by our group (Eur J Haematol, 2006). Ex vivo expanded allogeneic MSC were intravenously infused at the dose of 1×10⁶ MSC/kg of recipient body weight. The conditioning regimen of the HSCT consisted in Fludarabine and ATG combination and 5× 10⁶ CD34 cells were infused concomitantly with 1.10⁶ MSC cells. We did not observed any immediate or delayed side effects after the MSC infusion. The patient did not presented any complications after the HSCT. At day 8 of the transplantation she had an normal hematological recovery. The platelet nadir was 72.000/mm³ and she did not need any transfusion. With regards of her neurological status, since 22 months the patient had no new deterioration and we observed a stabilisation of the clinical manifestations.

Conclusions: This case report suggests the feasibility and the potential efficacy of reduced intensity conditioning allogeneic HSCT with MSC infusion for patient with MLD. A larger trial is required to confirm this observation.