Rosenau, Emma

Abstract Background Umbilical cord blood (UCB) is an important alternative source of stem cells for patients who lack matched adult donors, particularly in ethnic minorities. The infused total nucleated cell (TNC) and CD34+ cell dose are important prognostic factors on transplant outcomes. UCB units collected from African Americans (AA) have lower TNC and CD34+ cell counts and more likely to be disqualified for banking compared to other racial and ethnic groups. Furthermore, AA, including pregnant women, have increased prevalence of vitamin D deficiency. Vitamin D has an established role in hematopoiesis; therefore, we investigated the racial differences in UCB vitamin D content and its correlation with UCB cell composition and hematopoietic potential. Methods 119 UCB units that did not meet the TNC count banking criteria were analyzed. 51 UCB units were collected from AA mothers and 68 from Caucasian mothers. We analyzed UCB variables including volume, hematocrit (HCT), TNCs, mononucleated cells (MNC), CD34+ cells, plasma 25-Hydroxy vitamin D [25(OH)D] and in vitro progenitor cell hematopoietic potential measured by Colony-Forming Cell (CFC) assay. Results The median values of 25(OH)D in UCB units were significantly lower in AA compare to Caucasians (p= <.0001). Severe vitamin D deficiency < 10 ng/mL was exclusively detected in UCB units from AA (19/51; 37%) and plasma 25(OH)D concentration < 20 ng/mL was more prevalent in AA (43/51 units; 84%), compare to Caucasians (15/68 units; 22%). UCB units from AA had lower absolute numbers of TNC (p= .0016), MNC (p= .0261), and CD34+ cells (p= .0257) compare to Caucasians. No difference in median CFC/10,000 MNC was detected between AA and Caucasians (p= 0.661) (Table 1). Univariate analysis of 25(OH)D effect on UCB variables revealed a correlation between 25(OH)D level and TNC (r= 0.193, 95% CI 0.013-0.36; p= .0353) and UCB HCT (r= 0.196, 95% CI 0.016-0.363; p= .0327). A significantly higher MNC count was noted when 25(OH)D concentration was ≥ 20ng/mL (4.5x 108, range (1.7-9.5) vs. 3.9x 108, range (0.8-9); p= .0329). This correlation between 25(OH)D level and TNC and MNC was not detected after adjustment for race (Figure 1). However, 25(OH)D concentration ≥ 20 ng/mL significantly correlated with CBU HCT in AA race (median 31.9% (24-42) vs. 27.8%, range (21.4 - 40); p= .0124). Conclusion 25(OH)D level, TNC and HCT are all significantly lower in UCB units from AA compare to Caucasians. Independent of race, 25(OH)D directly correlated with TNC and MNC. These data suggest vitamin D and other yet to be determined factors play an important role in the mechanism of low UCB cell and progenitor counts. Disclosures: No relevant conflicts of interest to declare.

BACKGROUNDUmbilical cord blood (UCB) units collected from African Americans (AAs) have lower total nucleated cell (TNC) and CD34+ cell counts and are more likely to disqualify for banking compared to other ethnic groups. Furthermore, AAs have higher prevalence of 25‐hydroxyvitamin D (25(OH)D) deficiency. Given the importance of 25(OH)D in hematopoiesis, we examined the racial differences in UCB unit 25(OH)D content and its correlation with UCB cellular characteristics.STUDY DESIGN AND METHODSA total of 119 UCB units that did not meet the TNC count banking criteria were analyzed. Fifty‐one UCB units were collected from AA mothers and 68 from Caucasian mothers. We analyzed UCB volume, hematocrit (Hct), TNCs, mononuclear cells (MNCs), CD34+ cells, plasma 25(OH)D concentration, and progenitor clonogenic capacity measured by colony‐forming cell (CFC) assay.RESULTSCompared to Caucasians, AAs had significantly lower UCB 25(OH)D levels (p < 0.0001), TNCs (p = 0.002), MNCs (p = 0.026), and CD34+ cells (p = 0.026). Severe deficiency (25(OH)D < 10 ng/mL) was only detected in AAs. No difference in median CFC count/10,000 MNCs was detected between AAs and Caucasians. Independent of race, a significant association was detected between 25(OH)D level and TNCs (r = 0.193 p = 0.035) and Hct (r = 0.196 p = 0.033).CONCLUSIONThese results indicate the importance of 25(OH)D level as a racially independent predictor of UCB cellular characteristics and support further investigation of bioactive vitamin D and other predictors of hematopoiesis on cord blood quality.