Multiple BM harvests in pediatric donors for thalassemic siblings: safety, efficacy and ethical issues

Bone marrow harvesting from paediatric patients undergoing haematopoietic stem cell gene therapy

Collection of an adequate amount of autologous haematopoietic stem progenitor cells (HSPC) is required for ex vivo manipulation and successful engraftment for certain inherited disorders. Fifty-seven paediatric patients (age 0.5–11.4 years) underwent a bone marrow harvest for the purpose of HSPC gene therapy (GT), including adenosine deaminase-severe combined immunodeficiency (ADA-SCID), Wiskott–Aldrich syndrome (WAS) and metachromatic leukodystrophy (MLD) patients. Total nucleated cells and the percentage and absolute counts of CD34+ cells were calculated at defined steps of the procedure (harvest, CD34+ cell purification, transduction with the gene transfer vector and infusion of the medicinal product). A minimum CD34+ cell dose for infusion was 2 × 10⁶/kg, with an optimal target at 5–10 × 10⁶/kg. Median volume of bone marrow harvested was 34.2 ml/kg (range 14.2–56.6). The number of CD34+ cells collected correlated inversely with weight and age in all patients and particularly in the MLD children group. All patients reached the minimum target dose for infusion: median dose of CD34+ cells/kg infused was 10.3 × 10⁶/kg (3.7–25.9), with no difference among the three groups. Bone marrow harvest of volumes > 30 ml/kg in infants and children with ADA-SCID, WAS and MLD is well tolerated and allows obtaining an adequate dose of a medicinal product for HSPC-GT.

Peripheral blood stem cell transplantation in a significant body weight difference between a smaller donor and a larger recipient: a case report

Allogeneic peripheral blood stem cell transplantation (PBSCT) is becoming a common transplantation procedure in children. However, few benefits have been reported, in particular in regard to the choice of small children as donors for larger recipients. We report a case of relapsed acute myeloid leukemia (body weight 52 kg and blood type O) who underwent allogeneic PBSCT from his smaller human leukocyte antigen-matched brother (body weight 29.9 kg and blood type A).