Effect of CD34⁺ Total/Myeloid CD34⁺ Cell Progenitors and B-Lymphoid Progenitors Within the Bone Marrow Grafts on the Hematopoietic Recovery After Hematopoietic Stem Cell Transplantation.

OBJECTIVES: The influence of CD34⁺ cells on transplant outcomes following hematopoietic stem cell transplantation remains controversial. A minimum of 2.0 to 2.5 million CD34⁺ cells/kg of patient weight is requested for a rapid and durable engraftment. The aim of this study was to detect the ratio of CD34+ B-lymphoid progenitors (hematogones) in bone marrow grafts and investigate their effects on hematopoietic recovery after transplant. MATERIALS AND METHODS: Our study included 41 patients who received a bone marrow graft from their HLA-matched donor from 2016 through 2019. The CD34⁺ cell numbers within the graft were detected using Stem-Kit (Beckman Coulter). The ratio of CD34⁺ hematogones was determined either by their light scatter characteristics or by the detection of CD34, CD19, or CD10 coexpressing cells in a separate tube. RESULTS: The median number of CD34⁺ cells was 5.9 × 106/kg (0.8-14.3 × 106/kg). The CD34⁺ cells consisted of 71% (range, 35.7%-100%) and 29% (range, 5.7%-64.3%) myeloid and B-lymphoid progenitors, respectively. Percentage of CD34⁺ (P < .001) and total (P < .001) hematogones in correlation with donor age. Time of neutrophil engraftment was significantly longer (P = .039) when total infused CD34⁺ cell content was <3 × 106/kg. CONCLUSIONS: A remarkable population of hematogones within the CD34⁺ cell pool was detected in bone marrow grafts. Detection of the ratio of hematogones and most primitive stem cells (CD34⁺CD90⁺CD38⁻) may overall provide more information to build a better correlation between CD34⁺ cell content and the recovery of bone marrow.