CD14 positive cells accelerate hematopoietic stem cell engraftment

Immunophenotypic and Functional Interindividual Variability in Banked Cord Blood Cells: Insights for Advanced Therapies

Umbilical cord blood (UCB) is an alternative therapeutic resource for treating both hematological and non-hematological diseases, especially for pediatric patients. However, UCB transplantation faces challenges, including delayed engraftment, increased risk of graft failure, and slower immune recovery. To maximize its clinical potential, it is essential to understand the variability and functionality of its nucleated cells. This study focused on characterizing UCB cellular populations, viability, and functionality at three key processing stages: freshly collected, post-volume reduction, and post-thawing. Using EuroFlow-based flow cytometry, significant changes were observed in granulocyte and T-cell populations during processing. Additionally, integrating EuroFlow data with hematology counts revealed variability that could affect the yield of specific cell populations, potentially influencing therapeutic decisions. An in vitro migration assay, designed to mimic the vascular niche, was employed to study donor variability in cellular migratory patterns. Notably, thawed UCB cells displayed two distinct migration profiles, distinguishing lymphocyte-like cells from monocyte-like cells. These findings underscore the importance of reproducible cellular quality control measures, such as immunophenotypic and functional donor characterization, to ensure the integrity of UCB composition. A better understanding of these parameters could improve the consistency and reliability of UCB as a starting material for the development of advanced therapies.

Macrophage depletion damages hematopoiesis partially through inhibition of cell homing and expansion after hematopoietic cell transplantation

Bone marrow macrophages (Mφ) are essential components of the bone marrow niche that regulate the function of hematopoietic stem cells. Poor graft function and inhibition of hematopoietic production can result from abnormal macrophage function; however, the underlying mechanism is unclear. Clodronate liposomes (Clo-Lip) have been used widely to deplete macrophages and study their functions. Our previous results showed that Clod-Lip-mediated clearance of macrophages plays a vital role in regulating hematopoietic reconstruction after allogeneic hematopoietic cell transplantation (HCT). In this study, using an isogenic hematopoietic stem cell transplantation model, we found that Clod-Lip-mediated clearance of macrophages suppressed hematopoietic reconstruction by inhibiting the homing process of hematopoietic cells. We also demonstrated that macrophage depletion inhibited the direct supportive effect of macrophages on hematopoietic stem and progenitor cells and erythroid differentiation but promoted the production of megakaryocytic progenitors ex vivo. We showed that macrophages increase CD49e expression on hematopoietic stem and progenitor cells (HSPCs). However, CD49e inhibitors did not support the proliferative effect of macrophages on hematopoietic cells. In contrast, macrophage E-selectin/ intercellular cell adhesion molecule-1 (ICAM-1) may be involved in directly regulating HSPCs. In conclusion, macrophage depletion with Clo-Lip partially disrupts bone marrow hematopoiesis after HCT by impeding donor cell homing and macrophage-HSPCs interactions.

Characterization of a Stemness-Optimized Purification Method for Human Dental-Pulp Stem Cells: An Approach to Standardization

Human dental pulp stem cells (hDPSCs) are promising for oral/craniofacial regeneration, but their purification and characterization is not yet standardized. hDPSCs from three donors were purified by magnetic activated cell sorting (MACS)-assisted STRO-1-positive cell enrichment (+), colony derivation (c), or a combination of both (c/+). Immunophenotype, clonogenicity, stemness marker expression, senescence, and proliferation were analyzed. Multilineage differentiation was assessed by qPCR, immunohistochemistry, and extracellular matrix mineralization. To confirm the credibility of the results, repeated measures analysis and post hoc p-value adjustment were applied. All hDPSC fractions expressed STRO-1 and were similar for several surface markers, while their clonogenicity and expression of CD10/44/105/146, and 166 varied with the purification method. (+) cells proliferated significantly faster than (c/+), while (c) showed the highest increase in metabolic activity. Colony formation was most efficient in (+) cells, which also exhibited the lowest cellular senescence. All hDPSCs produced mineralized extracellular matrix. Regarding osteogenic induction, (c/+) revealed a significant increase in mRNA expression of COL5A1 and COL6A1, while osteogenic marker genes were detected at varying levels. (c/+) were the only population missing BDNF gene transcription increase during neurogenic induction. All hDPSCs were able to differentiate into chondrocytes. In summary, the three hDPSCs populations showed differences in phenotype, stemness, proliferation, and differentiation capacity. The data suggest that STRO-1-positive cell enrichment is the optimal choice for hDPSCs purification to maintain hDPSCs stemness. Furthermore, an (immuno) phenotypic characterization is the minimum requirement for quality control in hDPSCs studies.