Factors affecting the CD34+ cell yields from the second donations of healthy donors: The steady-state lymphocyte count is a good predictive factor

Improving cellular therapy operations through pre-harvest measurement of peripheral CD34-positive cell counts in allogeneic stem cell harvest

INTRODUCTION

Previously, our institution measured peripheral blood CD34 cell counts both pre- and post-peripheral blood stem cell harvest (PBSCH), with both samples analyzed simultaneously post-PBSCH. Since 2021, we have measured pre-CD34 cell counts during PBSCH, adjusting the processed blood volume based on these results. We retrospectively evaluated how this change impacted cellular therapy.

METHODS

Related healthy donors were included and divided into 1-day and 2-day harvest cohorts. Donors with CD34 cell counts measured post- and during PBSCH were categorized into the previous and current sub-cohorts, respectively.

RESULTS

Regarding the 1-day cohort (n = 212), the current sub-cohort had a significantly shorter average harvest duration (151 [standard deviation, SD = 45.1] vs. 180 [SD = 27.8] minutes, respectively) and higher average infusion rates (87.6% [SD = 21.1] vs. 78.1% [SD = 25.7], respectively) than the previous sub-cohort.

CONCLUSION

Adjusting the processed blood volume based on pre-PBSCH CD34 cell counts measured during the harvest may reduce donor burden and enhance workflow efficiency.

Shorter Interdonation Interval Contributes to Lower Cell Counts in Subsequent Stem Cell Donations

Approximately 7% of unrelated hematopoietic stem cell donors are asked to donate stem cells a subsequent time to the same or a different recipient. Recent studies have shown that donation-related symptoms for second donations are similar to those for the first donation. Little is known about differences in stem cell mobilization and yields for subsequent peripheral blood stem cell (PBSC) and bone marrow (BM) collections. We hypothesized that CD34⁺ cell yields and total nucleated cell (TNC) concentrations for subsequent PBSC or BM donations are lower than those at the first donation. We also evaluated the factors influencing stem cell yields in healthy unrelated second-time donors. Data were gathered from the Center for International Blood and Marrow Transplant Research database on 513 PBSC and 43 BM donors who donated a second time between 2006 and 2017 through the National Marrow Donor Program. Among the second-time PBSC donors, we found significantly lower preapheresis peripheral blood CD34⁺ cell counts (68.6 × 10⁶/L versus 73.9 × 10⁶/L; P = .03), and collection yields (556 × 10⁶ versus 608 × 10⁶; P = .02) at the second donation compared to the first. This decrease at the subsequent donation was associated with a shorter interdonation interval, lower body mass index (BMI), and a lower total G-CSF dose. In most instances, suboptimal mobilizers at their first donation donated suboptimal numbers of stem cells at their subsequent donations. Among repeat BM donors, the TNC concentration was lower at the second donation. The small size of this group precluded additional analysis. Overall, when considering repeat donations, increasing the interdonation intervals and evaluating for BMI changes should be considered to optimize stem cell yields. Some of these parameters may be improved by increasing G-CSF dose in PBSC donors within permissible limits.