Can the bone marrow harvest volume be reduced safely in hematopoietic stem cell transplantation with pediatric sibling donors?

Background: Reduced harvest volumes in pediatric donors appear to have the potential to reduce donor-associated risks while maintaining engraftment in recipients; however, the allowable harvest volume reduction remains undefined.

Methods: We retrospectively analyzed the data pairs of 553 bone marrow (BM) harvests from pediatric (age at harvest <18 yr) sibling donors and clinical outcomes of 553 pediatric (age at infusion <14 yr) transplant-naïve recipients to assess the optimal BM harvest volume needed from pediatric donors to obtain the desired CD34+ cell count (≥3.0×10⁶ cells per kg of recipient weight), and to study its impact on the clinical outcomes of transplantation in pediatric recipients.

Results: The minimum desired CD34+ cell count of ≥3.0×10⁶ per kg of recipient weight was achieved for 506 (95.3%) of donor-recipient pairs. The median CD34+ cell yield was 6.4×10⁶ per kg of recipient weight (range, 1.2‒33.8×10⁶) in donors younger than 5 years old at harvest, 4.7×10⁶ (range, 0.3‒28.5×10⁶) in donors aged 5‒10 years and 2.1×10⁶ (range, 0.3‒11.3×10⁶) in donors older than 10 years (P<0.001).

Conclusion: The infused CD34+ cell dose (×10⁶ cells/kg of recipient weight) had no impact on GRFS; however, a CD34+ cell dose of ＞7×10⁶ cells/kg of recipient weight did not improve hematopoietic recovery.