Abstract: Objective To investigate the determinants that influence the efficiency of autologous hematopoietic stem cell harvests. Methods A retrospective cohort study was performed at Shengjing Hospital from January 2018 to January 2023, including 140 autologous hematopoietic stem cell harvesting procedures. The collections were stratified into two cohorts based on the yield of CD34⁺ cells: a 'favorable' cohort with a CD34⁺ cell count of ≥2×10⁶/kg, and a 'suboptimal' cohort with counts <2×10⁶/kg. Comparative analyses were done to scrutinize variances across a spectrum of parameters between the cohorts. These parameters were demographic data (gender, age, weight), clinical diagnosis, processed blood volume, nadir days, low point white blood cell level, interval from nadir to collection, leukocyte counts prior to and on the day of collection, lymphocyte and monocyte counts on the day of collection, hemoglobin levels and hematocrit values on the day of collection, volume of stem cell harvested, and total processing volume. Results The comparative analysis revealed significant disparities between the two cohorts in several categories, including clinical diagnosis and gender. Notably, the median duration to reach the leukocyte nadir diverged between the cohorts（median 8.0 vs 7.0 d, P<0.05）, as did the median leukocyte count at nadir （median 0.9×10⁹/L vs 0.4×10⁹/L, P<0.05）, and the median interval from nadir to collection (median 4.0 d vs 6.0 d, P<0.05). On the day of collection discernible differences were observed in leukocyte counts (median 10.8×10⁹/L vs 7.5×10⁹/L, P<0.001), monocyte counts (median 2.1×10⁹/L vs 1.3×10⁹/L, P<0.001) and lymphocyte counts (median 1.1×10⁹/L vs 0.7×10⁹/L, P<0.05), hemoglobin levels (median 97.0 g/L vs 91.0 g/L, P<0.05) and hematocrit percentages (median 29.2% vs 25.9%, P<0.05), alongside the circulating blood volume (median 9 112 mL vs 9 998 mL, P<0.05). Critical independent risk factors, which could affect the collection effect, were identified, i.e. the patient age（median 49 y vs 52 y）, the elapsed time from nadir to collection (median 4.0 d vs 6.0 d), and the monocytes count on the collection day(median 2.1×10⁹/L vs 1.3×10⁹/L). Conclusion A multifaceted array of factors potentially affect the efficacy of autologous hematopoietic stem cell collection. Among these, patient age, the interval from leukocyte nadir to collection, and the monocyte count on the collection day stand out as independent risk factors that could influence the outcome of the stem cell harvest.

Key words: Hematopoietic stem cell, Peripheral blood stem cell collection, Risk factor