Cord Blood Hematopoietic Stem Cells Research Articles

Detection of CRISPR/Cas9-Mediated Fetal Hemoglobin Reactivation in Erythroblasts Derived from Cord Blood-Hematopoietic Stem Cells.

Reactivation of the fetal hemoglobin (HbF) in adult erythroid cells via genome editing is a strategy for the treatment of β-thalassemia and sickle cell disease. In related reports, the reactivation of HbF is regularly examined in erythroblasts which are generated from the adult CD34+ hematopoietic stem and progenitor cells (HSPCs). However, the procurement of adult HSPCs, either from the bone-marrow (BM) or from mobilized peripheral-blood (mPB), is difficult. Cord-blood (CB) is a readily available source of HSPCs. CB-HSPCs, however, produce high quantities of HbF following differentiation into the erythroid lineage-a potential drawback in such studies. Here, we have edited the BCL11A enhancer (a well-characterized HbF-quantitative trait loci or QTL) via CRISPR/Cas9 in order to determine whether HbF reactivation could be detected in CB-HSPC-derived erythroblasts. In the edited erythroblasts, insertion/deletion (indel) frequencies of 74.0-80.4% and BCL11A RNA reduction levels of 92.6 ± 5.1% (P < 0.0001) were obtained. In turn, the γ/β-globin transcript ratios were increased from 11.3 ± 1.1-fold to 77.1 ± 2.0-fold, i.e., by 6.8-fold (P < 0.0001)-and the HbF% levels increased from 34.3% in the control population to 43.5% in the BCL11A edited erythroblasts. Our results suggest that γ-globin/HbF reactivation via genome editing can be detected in CB-HSPCs generated erythroblasts-rendering CB-HSPCs a useful model for similar studies.

Impact of donor NKG2D and MICA gene polymorphism on clinical outcomes of adult and paediatric allogeneic cord blood transplantation for malignant diseases.

NKG2D is an activating receptor expressed by natural killer (NK) and CD8+ T cells and activation intensity varies by NKG2D expression level or nature of its ligand. An NKG2D gene polymorphism determines high (HNK1) or low (LNK1) expression. MICA is the most polymorphic NKG2D ligand and stronger effector cell activation associates with methionine rather than valine at residue 129. We investigated correlation between cord blood (CB) NKG2D and MICA genotypes and haematopoietic stem cell (HSC) transplant outcome. We retrospectively studied 267 CB HSC recipients (178 adult and 87 paediatric) who underwent transplant for malignant disease between 2007 and 2018, analysing CB graft DNA for NKG2D and MICA polymorphisms using Sanger sequencing. Multivariate analysis was used to correlate these results with transplant outcomes. In adult patients, LNK1 homozygous CB significantly improved 60-day neutrophil engraftment (hazard ratio (HR) 0.6; 95% confidence interval (CI) 0.4-0.9; p = .003). In paediatrics, HNK1 homozygous CB improved 60-day engraftment (HR 0.4; 95% CI 0.2-0.7; p = .003), as did MICA-129 methionine+ CB grafts (HR 1.7 95% CI 1.1-2.6; p = .02). CB NKG2D and MICA genotypes potentially improve CB HSC engraftment. However, results contrast between adult and paediatric recipients and may reflect transplant procedure disparities between cohorts.

In vivo and in vitro effects of cord blood hematopoietic stem and progenitor cell (HSPC) expansion using valproic acid and/or nicotinamide

BackgroundHigh self-renewal capacity and most permissive nature of umbilical cord blood (CB) results with successful transplant outcomes but low hematopoietic stem and progenitor cell (HSPC) counts limits wider use. In order to overcome this problem ex vivo expansion with small molecules such as Valproic acid (VPA) or Nicotinamide (NAM) have been shown to be effective. To the best of our knowledge, the combinatory effects of VPA and NAM on HSPC expansion has not been studied earlier. The aim of this study was to analyze ex vivo and in vivo efficacy of VPA and NAM either alone or in combination in terms of expansion and engraftment. MethodsA total of 44 CB units were included in this study. To determine the ex vivo and in vivo efficacy, human CB CD34+ cells were expanded with VPA and/or NAM and colony forming unit (CFU) assay was performed on expanded HSPC. Xenotransplantation was performed simultaneously by intravenous injection of expanded HSPC to NOD-SCID gamma (NSG) mice (n = 22). Significance of the difference between the expansion groups or xenotransplantation models was analyzed using t-test, Mann-Whitney, ANOVA or Kruskal-Wallis tests as appropriate considering the normality of distributions and the number of groups analyzed. ResultsIn vitro CD34+ HSPC expansion fold relative to cytokines-only was significantly higher with VPA compared to NAM [2.23 (1.07–5.59) vs 1.48 (1.00–4.40); p < 0.05]. Synergistic effect of VPA+NAM has achieved a maximum relative expansion fold at 21 days (D21) of incubation [2.95 (1.00–11.94)]. There was no significant difference between VPA and VPA+NAM D21 (p = 0.44). Fold number of colony-forming unit granulocyte-macrophage (CFU-GM) colonies relative to the cytokine-only group was in favor of NAM compared to VPA [1.87 (1.00–3.59) vs 1.00 (1.00–1.81); p < 0.01]. VPA+NAM D21 [1.62 (1.00–2.77)] was also superior against VPA (p < 0.05). There was no significant difference between NAM and VPA+NAM D21. Following human CB34+ CB transplantation (CBT) in the mouse model, fastest in vivo leukocyte recovery was observed with VPA+NAM expanded cells (6 ± 2 days) and the highest levels of human CD45 chimerism was detectable with VPA-expanded CBT (VPA: 5.42 % at day 28; NAM: 2.45 % at day 31; VPA+NAM 1.8 % at day 31). ConclusionOur study results suggest using VPA alone, rather than in combination with NAM or NAM alone, to achieve better and faster expansion and engraftment of CB HSPC.

Potential Perturbations of Critical Cancer-regulatory Genes in Triple-Negative Breast Cancer Cells Within the Humanized Microenvironment of Patient-derived Xenograft Models.

In this study, we aimed to establish humanized patient-derived xenograft (PDX) models for triple-negative breast cancer (TNBC) using cord blood (CB) hematopoietic stem cells (HSCs). Additionally, we attempted to characterize the immune microenvironment of the humanized PDX model to understand the potential implications of altered tumor-immune interactions in the humanized PDX model on the behavior of TNBC cells. To establish a humanized mouse model, high-purity CD34+ HSCs from CB were transplanted into immunodeficient NOD scid γ mice. Peripheral and intratumoral immune cell compositions of humanized and non-humanized mice were compared. Additionally, RNA sequencing of the tumor tissues was performed to characterize the gene expression features associated with humanization. After transplanting the CD34+ HSCs, CD45+ human immune cells appeared within five weeks. A humanized mouse model showed viable human immune cells in the peripheral blood, lymphoid organs, and in the tumor microenvironment. Humanized TNBC PDX models showed varying rates of tumor growth compared to that of non-humanized mice. RNA sequencing of the tumor tissue showed significant alterations in tumor tissues from the humanized models. tumor necrosis factor receptor superfamily member 11B (TNFRSF11B) is a shared downregulated gene in tumor tissues from humanized models. Silencing of TNFRSF11B in TNBC cell lines significantly reduced cell proliferation, migration, and invasion in vitro. Additionally, TNFRSF11B silenced cells showed decreased tumorigenicity and metastatic capacity in vivo. Humanized PDX models successfully recreated tumor-immune interactions in TNBC. TNFRSF11B, a commonly downregulated gene in humanized PDX models, may play a key role in tumor growth and metastasis. Differential tumor growth rates and gene expression patterns highlighted the complexities of the immune response in the tumor microenvironment of humanized PDX models.

Investigation of CD83 As a Novel Human Hematopoietic Stem Cell Inflammatory Activation Marker

Hematopoietic stem cells (HSC) are responsible for life-long blood production and must balance homeostasis with sudden demand situations such as infections. However, the heterogeneity of molecular programs engaged by acute inflammatory stimuli to activate emergency hematopoiesis at the level of HSC are poorly understood. In a recent study linking human HSC heterogeneity to aging, recovery from severe COVID-19 infection, and clonal hematopoiesis (CH), we discovered two HSC subsets through multiomic analysis, denoted HSC-I and -II, in a xenograft model of inflammation-recovery. While HSC-I had few inflammation-driven molecular changes, HSC-II showed sustained epigenetic and transcriptional alterations in response to dual tumor necrosis factor α (TNFα) or lipopolysaccharide (LPS) challenges despite a 2.5-month recovery period. Importantly, a signature of long-term memory T cells (Akondy et al 2017) was enriched in HSC-II (Zeng, Nagree, et al, in submission). We interrogated the human HSC multiomic signatures uncovered from this human xenograft model to identify potential regulators associated with HSC response to and recovery from acute inflammation. We identified CD83 as a candidate that is differentially expressed between our HSC subsets. Similarly, we found CD83 expression to be enriched in a subset of adult-derived HSCs from patients where CH status was established and enrichment of an HSC-II signature observed (Jakobsen et al, submitted). CD83, first identified as a dendritic cell marker, is expressed on many immune cells, with linkage to controlling murine T regulatory (T-Reg) vs memory cell fate (Doebbeler et al, 2018), but has not previously been shown to be relevant for human HSC biology. Flow cytometry analysis of cord blood (CB) hematopoietic stem and progenitor cells (HSPC) showed CD83 to be low or absent in HSC (Figure A) and their downstream progeny at steady state. However, robust CD83 expression was observed in multiple HSPC subpopulations including long-term (LT-) and short-term (ST-) HSC within 16 hours of ex vivo culture, with highest expression in LT-HSC (Figure A). Importantly, CD83 surface expression on LT-HSC was enhanced following culture with TNFα (Figure A). Bystander effects were excluded by demonstrating similar findings after culture of purified HSC populations. Acute in vivo LPS treatment of mice xenografted with CB-derived HSC was sufficient to upregulate CD83 surface expression after 16 hours on LT-HSC/HSPC. To elucidate the potential function of CD83-expressing HSC/multipotent progenitors (MPP), CD19-CD34+CD38-CD45RA- cells were sorted from xenografts following acute inflammatory challenge for low and high CD83 expression and subjected to bulk RNA sequencing. We found enrichment of a gene expression signature specific to activated human HSCs (Garcia-Prat et al, 2021) within CD83-positive HSC/MPP (Figure B). Strikingly, enrichment of a signature of stimulated vs resting T cells (Galetti et al, 2020) and of effector T cells (Akondy et al 2017) was found in CD83-positive compared to CD83-negative HSC/MPP (Figure B). T cell effector function is in part dictated by metabolic reprogramming. We thus examined reactive oxygen species (ROS) levels in LT-HSC following ex vivo culture with TNFα and found lower ROS levels with CD83 expression. We therefore hypothesize that CD83 may be an ‘effector’ marker defining a distinct HSC subset during homeostatic or inflammatory activation that is subsequently fated to become memory-like HSC-II. We are undertaking studies to determine the mechanistic role of CD83 in HSC function and HSC-II formation via Cas9-sgRNA-mediated knockout or lentivirus-mediated overexpression of CD83. In summary, CD83 represents a long-sought marker of inflammatory activation at the HSC level. CD83 may have significant clinical potential as a biomarker of aberrant activation in gene therapy manufacturing protocols or for HSC transplantation. Future studies will shed light on whether CD83 can functionally regulate the molecular programs underlying human HSC heterogeneity.

Single Cell Analyses Indicate SRSF2 and TET2 Co-Mutation Results in Skewed Haematopoiesis in Myelodysplastic Syndromes

We used single-cell ATAC-seq (scATAC-seq) to study how synchronous SRSF2 and TET2 co-mutations result in skewed myelopoiesis compared with SRSF2 mutation only in subjects with myelodysplastic neoplasms (MDNs). We identified 621 differentially expressed genes in comparing of transcriptome sequencing data of bone marrow mononuclear cells ( p &amp;lt; 0.01; |log2FC| &amp;gt; 2; Figure 1 A). Up-regulated genes in the co-mutation cohort involved those expressed in pluripotent haematopoietic stem cells (HSCs), cytokine receptor interactions and cancer-related signaling pathways ( Figure 1 B). We extended our observation by interrogating data from the GSE58831 public dataset where we identified 18 similar pathways in subjects with SRSF2 and TET2 co-mutations ( Figure 1 C ). We then used scATAC-seq to verify regulatory networks with genes and transcription factors. 49,532 cells had high-quality scATAC-seq profiles and passed stringent quality filtering with a median of 12,858 fragments per cell 39% of which mapped to peaks. 16 cell types were annotated according to cell marker genes and aligned with the public single cell RNA-seq gene expression matrix of haematopoietic cell types ( Figure 1 D-E). Next, we compared transcription factor (TF) and cis-elements active during differentiation of HSC to myelopoiesis betweenthe SRSF2 and TET2 co-mutation and SRSF2 mutation-only cohorts. In the SRSF2 and TET2 co-mutation cohort we found GATA4, RUNX1, SNAI1, REL and JDP2 favour myeloid differentiation and in NF-KB related inflammatory responses. Related gene activity correlated with high activity of inflammatory cytokines such as BCL2A1, EGR1, IL-1β, and NLRP3( Figure 1 F). SRSF2 and TET2 co-mutations result in early clonal dominance at the haematopoietic stem cell stage. 19,836 peaks were accessible in SRSF2 and TET2 co-mutated samples and annotated for putative functions by GREAT ontology enrichment analysis ( Figure 1 G-H). More accessibility peaks in SRSF2 and TET2 co-mutation were restricted to cancer-related process (reactive oxygen species biosynthetic process, regulation of phagocytosis, intrinsic apoptotic signaling pathway, mRNA catabolism) and cytokine related pathways (IL-1 mediated signaling pathway) compared with SRSF2 mutation-only samples. Next, we focused on the IL-1-mediated signaling pathway, a regulator of HSC function. We isolated umbilical cord blood HSCs (CD34+) monitored their expansion in liquid culture with or without (IL-1A or IL-1B (25 ng/ml). HSCs cultured with IL-1A or IL-1B differentiated and expanded significantly faster than untreated HSCs over 7-day period ( Figure 1 I). To directly address the effects of IL-1 on HSC differentiation we used colony formation assays in methylcellulose ± IL-1. Strikingly, IL-1-treated HSCs produced almost exclusively myeloid-committed granulocyte/macrophage (GM)-type colonies containing abundant macrophages (CFU-GM), a higher proportion of immature multi-lineage granulocyte/ erythrocyte /macrophage/megakaryocyte (CFU-GEMM)-type colonies containing mostly immature myeloblasts and a lower proportion of burst-forming unit-erythroid (BFU-E). IL-1-treated HSCs also had decreased re-placing capacity ( Figure 1 J-K). Next, we constructed a SRSF2 P95H single mutation and SRSF2 P95H mutation with TET2 knockout cell lines. We found that co-mutant cells had significantly increased NLRP3 and IL-1β expression in LPS (1 ug/ml) and ATP (5 mM) treated cultures whereas no change was detected IL-1α expression ( Figure 1 L-M). In conclusion, our data preliminary indicate SRSF2 and TET2 co-mutated causes increased NLRP3-mediated IL-1β secretion resulting in skewed differentiation of HSCs in persons with MDNs.

Effect of cord blood double collection method on cord blood hematopoietic stem cell transplantation-related indices and blood gas analysis.

Umbilical cord blood has been widely used in clinical transplantation. Blood gas analysis of umbilical cord blood is routinely used to evaluate neonatal asphyxia. This study aimed to evaluate an improved umbilical cord blood collection method that does not affect the results of umbilical cord blood gas analysis and hematopoietic stem cell transplantation-related indices. Three hundred pregnant women were recruited between December 2019 and August 2022. In total, 270 umbilical cord blood samples were included and randomly divided into 3 groups. Group A was defined as the group in which both umbilical cord blood samples for hematopoietic stem cell transplantation and blood gas analysis were collected. Group B was defined as the group from which umbilical cord blood was collected for hematopoietic stem cell transplantation. Group C was defined as that wherein umbilical cord blood was collected only for blood gas analysis. Hematopoietic stem cell transplantation-related indices were detected in groups A and B, and blood gas analysis was performed in groups A and C. Hematopoietic stem cell transplantation-related indices were not significantly different between groups A and B. The pH, base excess, and lactic acid values were not significantly different between groups A and C. The cord blood double collection method would not affect the results of umbilical cord blood gas analysis and hematopoietic stem cell transplantation-related indices. It is suitable for cord blood collection when preparing for hematopoietic stem cell transplantation and blood gas analysis.

DNA Damage Response After Treatment of Cycling and Quiescent Cord Blood Hematopoietic Stem Cells With Distinct Genotoxic Noxae.

Hematopoietic stem cells (HSC) from cord blood can be applied as an alternative to bone marrow in transplantation to treat hematological diseases. Umbilical cord blood (UCB) consists of cycling and non-cycling CD34+/CD45low cells needed for long-term and short-term engraftment. After sorting and subsequent in vitro culture, quiescent HSCs enter the cell cycle. This enables the analysis of HSCs in 2 different cell cycle stages and the comparison of their responses to different genotoxic noxae. To analyze different mechanisms of DNA damage induction in cells, 2 different genotoxins were compared: etoposide, a topoisomerase II inhibitor that targets mitosis in the S/G2-phase of the cell cycle and the alkylating nitrosamine N-Nitroso-N-methylurea (MNU), which leads to the formation of methyl DNA adducts resulting in DNA double breaks during DNA replication and persistent mutations. Cycling cells recovered after treatment even with higher concentrations of etoposide (1.5µM/ 5µM/10µM), while sorted cells treated with MNU (0.1mM/0.3mM/0.5mM/1mM/3Mm/ 5mM) recovered after treatment with the lower MNU concentrations whereas high MNU concentrations resulted in apoptosis activation. Quiescent cells were not affected by etoposide treatment showing no damage upon entry into the cell cycle. Treatment with MNU, similarly to the cycling cells, resulted in a dose-dependent cell death. In conclusion, we found that depending on the genotoxic trigger and the cycling status, CD34+cells have distinct responses to DNA damage. Cycling cells employ both DDR and apoptosis mechanisms to prevent damage accumulation. Quiescent cells predominantly undergo apoptosis upon damage, but their cell cycle status protects them from certain genotoxic insults.

Vitamin C derivative/AA2P promotes erythroid differentiation by upregulating CA1

Abstract Vitamin C is used to treat anaemia; however, the mechanism through which vitamin C promotes erythroid differentiation is not comprehensively understood. The in vitro erythroid differentiation induction system can reveal the differentiation mechanism and provide erythrocytes for clinical transfusion and anaemia treatment. This process can be promoted by adding small-molecule compounds. In this study, we added l-ascorbic acid 2-phosphate sesquimagnesium salt hydrate (AA2P), a derivative of vitamin C, to an erythroid differentiation system induced from umbilical cord blood haematopoietic stem and progenitor cells in vitro and detected its effect on erythroid differentiation using single-cell transcription sequencing technology combined with non-targeted metabolism detection. AA2P increased the proportion of late basophilic erythroblasts, upregulating the expression of erythroid-related regulatory molecules GATA1, KLF1, ALAS2, and the globins HBG and HBB. CA1 is a target gene of AA2P, and CA1 knockdown affected the expression of globin-related genes. AA2P also increased glycolysis and decreased oxidative phosphorylation to facilitate terminal erythroid differentiation and enhanced the proliferation of early erythroid progenitors by altering the cell cycle. These results provide a reliable basis for using vitamin C to improve the efficiency of erythropoiesis in vitro and for the clinical treatment of anaemia.

Abstract 26 The Role of Oxygen in Cord Blood Hematopoietic Stem and Progenitor Cell Expansion and Engraftment

Abstract Introduction Hematopoietic stem (HSC) and progenitor cells (HPCs) are exposed to differing oxygen tensions ranging from &amp;lt;1% to 21% as they reside in/move through different tissues or are harvested for clinical utility. Functional changes in HSCs/HPCs are induced by acute changes in oxygen tension (e.g., a change in percent of cells in cycle). Objectives We sought to determine if variable oxygen levels affect expansion and/or functional properties of cord blood (CB) HSCs/HPCs ex vivo and in vivo. Methods Human CB CD34+ cells were grown in expansion culture +/-UM171, an agonist of HSC self-renewal that expands transplantable CB HSCs, in five oxygen tensions: 1%O2, 3%O2, 5%O2, 14%O2, and 21%O2. HSCs/HPCs were enumerated by flow cytometry. Functional HPCs were enumerated by plating in semi solid media for colony forming unit assays (CFU). Cell cycle and reactive oxygen species (ROS) were measured by flow cytometry. Ability of expanded cells to engraft was determined by transplantation in non-lethally irradiated NSG mice. Results Immunophenotypic HPCs and functional HPC CFUs expanded significantly more after 7 days of growth in higher oxygen tensions (5%O2-21%O2) compared to lower (1%O2-3%O2), while immunophenotypic HSCs expanded best at 5% O2. HSCs/HPCs grown in low oxygen tensions had significantly lower ROS levels, significantly higher percentage of cells in G0, and were slightly but reproducibly smaller/less granular than those grown in high oxygen levels. HSC/HPC numbers were reduced in high oxygen tensions 1-2 days after plating but were better maintained in low, suggesting cells undergo a culture shock/stress after plating that is mitigated by reduced oxygen. In the presence of UM171, HSCs expanded significantly better at higher oxygen levels, but HPCs are better maintained in 5%O2. Ex vivo CD34+ expansions maintained under physiological O2 levels (1-14%O2) demonstrated significantly better/faster neutrophil recovery following transplantation compared to cells expanded at 21%O2 or input. Discussion HSCs/HPCs proliferate rapidly in high oxygen but have fewer quiescent cells, higher ROS, and are larger and more granular which are all characteristics associated with exhaustion. While high oxygen allows for faster growth, low tensions may mitigate cell stress and allow for prolonged growth (i.e., HSC/HPC expansion) while maintaining functional properties.

Origin, phenotype and autoimmune potential of T cells in human immune system mice receiving neonatal human thymus tissue.

Robust human immune system (HIS) mice are created using human fetal thymus tissue and hematopoietic stem cells (HSCs). A HIS mouse model using neonatal human thymus tissue and umbilical cord blood (CB) HSCs (NeoHu) was recently described. We improved the model by removing the native murine thymus, which can also generate human T cells, and demonstrated definitively the capacity of human T cells to develop in a grafted neonatal human thymus. Human T cells derived from the neonatal thymus tissue appeared in peripheral blood early post-transplantation and CB-derived T cells appeared later. Naïve T cells were demonstrated in peripheral blood but effector memory and T peripheral helper phenotypes predominated later, in association with development of autoimmunity in some animals. Treatment of thymus grafts with 2-deoxyglucose (2-DG) increased the proportion of stem cells derived from injected HSCs, delayed onset of autoimmune disease, reduced early T cell reconstitution, and reduced effector/memory T cell conversion. Younger neonatal human thymus tissue was associated with improved T cell reconstitution. While the NeoHu model bypasses the need for fetal tissue, it has yet to demonstrate equivalent reconstitution to fetal tissue, though 2-DG can improve results by removing native thymocytes prior to transplantation.

Long-term expansion of human hematopoietic stem cells

Hematopoietic stem cells (HSCs) are critical for the treatment of a variety of hematological diseases. However, the low number of HSCs lead to the clinical application difficult. To gain more functional human HSCs ex vivo, Sakurai et al. established a recombinant-cytokine-free and albumin-free culture system, i.e. PCL-PVAc-PEG-based culture, in combination with 740Y-P, butyzamide and UM171, to improve the long-term expansion of human cord blood HSCs.

Ex vivo expansion of hematopoietic stem cells

Hematopoietic stem cells (HSCs) are multipotent progenitor cells that can differentiate into various mature blood cells and immune cells, thus reconstituting hematopoiesis. By taking advantage of the tremendous potential of HSCs, varied hereditary and hematologic diseases are promised to be alleviated or cured. To solve the contradiction between the growing demand for HSCs in disease treatment and the low population of HSCs in both cord blood and bone marrow, ex vivo HSC expansion along with multiple protocols has been investigated for harvesting adequate HSCs over the past two decades. This review surveys the state-of-the-art techniques for ex vivo HSC self-renewal and provides a concise summary of the effects of diverse intrinsic and extrinsic factors on the expansion of HSCs. The remaining challenges and emerging opportunities in the field of HSC expansion are also presented.

Albumin-based solution is the ideal post-thawing suspension medium for cord blood hematopoietic stem cells: A stability and proliferative evaluation.

Cryopreservation and thawing protocols represent key factors for the efficacy of cellular therapy products, such as hematopoietic stem cells (HSCs). While the HSC cryopreservation has already been standardized, the thawing procedures have been poorly studied. This study aimed to evaluate the thawing and washing protocol of cord blood (CB) derived HSCs or the HPC(CB), by selecting the optimal thawing solution and determining CD34+ cells' stability over time. Seven cryopreserved CB products were thawed, washed, and resuspended in three different solutions (10% Dextran40 in NaCl equally prepared with 5% human albumin; 5% human albumin in PBS/EDTA; and normal saline) and stored at 4°C (±2°C). Mononuclear cell (MNC) count, CD45+/CD34+ cell enumeration, and cell viability were tested at 0, 1, 2, 4, 6, 8, 12, 24, 36, and 48 h. The protocol with the selected solution was further validated on additional 10 CB samples. The above parameters and the colony-forming unit (CFU) assay were analyzed at time points 0, 2, 4, 6, and 8 h. The results showed that the 5% human albumin was the most suitable thawing solution. MNCs were stable up to 4 h (p = 0.009), viable CD45+ cells were unstable even at 2 h (p = 0.013), and viable CD34+ cells were stable until 6 h (p = 0.019). The CFU assay proved the proliferative potential up to 8 h, although significantly decreased after 4 h (p = 0.013), and correlated with the viable CD34+ cell counts. We demonstrated that the post-thawed and washed HPC(CB) using 5% human albumin is stable for up to 4 h.

Evaluation of DNA Damage and Repair In In Vitro Expanded Cord Blood CD 34 Positive Hematopoietic Stem Cell

Background and Aims: The occurrence of single and double-strand breaks of DNA damage is the major obstacle for proliferation under various environmental factors and, if not repaired, can result in many consequences, including mutation, cell death, and others. So, the present study was conducted to evaluate the damage of DNA and the expression status of DNA repair system genes before and after stem cell proliferation.&#x0D; Materials and Methods: The MACS method isolated the umbilical cord blood hematopoietic stem cells (UCB-HSCs). In order to investigate cell death, the study of Annexin V/PI was done by flow cytometry. Comet assay made observation and identification of DNA breaks, and the expression of genes normally involved in the repair of DNA breaks was evaluated by real-time polymerase chain reaction.&#x0D; Results: The average number of stem cells increased by 1.9-fold after three days of proliferation. The apoptotic percentage of cells was negligible (less than 0.2%), and the purity of the CD34+ cells was reduced by about one-third in three days (67%). By examining the expression of DNA repair genes, including KU70, KU80, RAD51, and XRCC1, their increased fold change was not significant. In a microscopic examination of stem cells in the comet assay, there was no significant difference between DNA damage before (1.33% ± 0.31) and after (2.08% ± 0.92) replication.&#x0D; Conclusion: In our investigation, neither DNA damage nor changes in the DNA break repair were observed. However, further studies are required to clarify the DNA break repair by recruiting more UCB-HSCs samples.

Chemically defined cytokine-free expansion of human haematopoietic stem cells.

Haematopoietic stem cells (HSCs) are a rare cell type that reconstitute the entire blood and immune systems after transplantation and can be used as a curative cell therapy for a variety of haematological diseases1,2. However, the low number of HSCs in the body makes both biological analyses and clinical application difficult, and the limited extent to which human HSCs can be expanded ex vivo remains a substantial barrier to the wider and safer therapeutic use of HSC transplantation3. Although various reagents have been tested in attempts to stimulate the expansion of human HSCs, cytokines have long been thought to be essential for supporting HSCs ex vivo4. Here we report the establishment of a culture system that allows the long-term ex vivo expansion of human HSCs, achieved through the complete replacement of exogenous cytokines and albumin with chemical agonists and a caprolactam-based polymer. A phosphoinositide 3-kinase activator, in combination with a thrombopoietin-receptor agonist and the pyrimidoindole derivative UM171, were sufficient to stimulate the expansion of umbilical cord blood HSCs that are capable of serial engraftment in xenotransplantation assays. Ex vivo HSC expansion was further supported by split-clone transplantation assays and single-cell RNA-sequencing analysis. Our chemically defined expansion culture system will help to advance clinical HSC therapies.

Umbilical Cord Blood Transplantation: Connecting Its Origin to Its Future.

Transplantation of umbilical cord blood (UCB) is an attractive alternative source of hematopoietic stem cells (HSCs). The unique properties of cord blood and its distinct immune tolerance and engraftment kinetics compared to bone marrow (BM) and peripheral blood progenitor cells, permit a wider disparity in human leukocyte antigen levels between a cord blood donor and recipient after an unrelated umbilical cord blood transplant (UCBT). In addition, it is readily available and has a lowered risk of graft-versus-host disease (GvHD), with similar long-term clinical outcomes, compared to BM transplants. However, the relatively low number of cells administered by UCB units, as well as the associated delayed engraftment and immune reconstitution, pose limitations to the wide application of UCBT. Research into several aspects of UCBT has been evaluated, including the ex vivo expansion of cord blood HSCs and the process of fucosylation to enhance engraftment. Additionally, UCB has also been used in the treatment of several neurodegenerative and cardiovascular disorders with varying degrees of success. In this article, we will discuss the biology, clinical indications, and benefits of UCBT in pediatric and adult populations. We will also discuss future directions for the use of cord blood.

Downregulation of circBIRC6 and circCORO1C during differentiation of human cord blood-derived CD34+ cells

BackgroundUmbilical cord blood hematopoietic stem cells (UCB HSCs) transplantation has attracted the attention of many researchers due to the low probability of GVHD and HLA mismatching; however, the use of this resource for adults has been limited due to the inadequate number of CD34+ HSC from any individual donor. Recent reports indicate that circular RNAs (circRNAs) are involved in stem cell properties. MethodsIn this study, the expression of several candidate circRNAs, including circCORO1C and circBIRC6 in CD34+ HSCs was investigated by using quantitative RT-PCR. ResultsThe results showed that the expression levels of circBIRC6 and circCORO1C and simultaneously, the expression of transcription factors such as NANOG and SOX2 were significantly downregulated during differentiation. ConclusionTaken together, these findings suggested that expression of circBIRC6 and circCORO1C were downregulated during differentiation of CD34+ HSCs.

Cord Blood Plasma and Placental Mesenchymal Stem Cells-Derived Exosomes Increase Ex Vivo Expansion of Human Cord Blood Hematopoietic Stem Cells While Maintaining Their Stemness.

Mesenchymal stem cells (MSCs) have been used for ex vivo expansion of umbilical cord blood (UCB) hematopoietic stem cells (HSCs) to maintain their primitive characters and long-term reconstitution abilities during transplantation. Therapeutic effects of MSCs mainly rely on paracrine mechanisms, including secretion of exosomes (Exos). The objective of this study was to examine the effect of cord blood plasma (CBP)-derived Exos (CBP Exos) and Placental MSCs-derived Exos (MSCs Exos) on the expansion of UCB HSCs to increase their numbers and keep their primitive characteristics. CD34+ cells were isolated from UCB, cultured for 10 days, and the expanded HSCs were sub-cultured in semisolid methylcellulose media for primitive colony forming units (CFUs) assay. MSCs were cultured from placental chorionic plates. CBP Exos and MSCs Exos compared with the control group significantly increased the number of total nucleated cells (TNCs), invitro expansion of CD34+ cells, primitive subpopulations of CD34+38+ and CD34+38-Lin- cells (p &lt; 0.001). The expanded cells showed a significantly higher number of total CFUs in the Exos groups (p &lt; 0.01). CBP- and placental-derived exosomes are associated with significant ex vivo expansion of UCB HSCs, while maintaining their primitive characters and may eliminate the need for transplantation of an additional unit of UCB.

The impacts of total body irradiation on umbilical cord blood hematopoietic stem cell transplantation.

Umbilical cord blood hematopoietic stem cells are commonly used for hematopoietic system reconstitution in recipients after umbilical cord blood transplantation (UCBT). However, the optimal conditioning regimen for UCBT remains a topic of debate. The exact impact of total body irradiation (TBI) as a part of conditioning regimens remains unknown. The aim of this study was to evaluate the impacts of TBI on UCBT outcomes. This was a multi-institution retrospective study. A retrospective analysis was conducted on the outcomes of 136 patients receiving UCBT. Sixty-nine patients received myeloablative conditioning (MAC), in which 33 underwent TBI and 36 did not, and 67 patients received reduced-intensity conditioning (RIC), in which 43 underwent TBI and 24 did not. Univariate and multivariate analyses were conducted to compare the outcomes and the post-transplant complications between patients who did and did not undergo TBI in the MAC subgroup and RIC subgroup, respectively. In the RIC subgroup, patients who underwent TBI had superior overall survival (adjusted hazard ratio [aHR] = 0.25, 95% confidence interval [CI]: 0.09-0.66, p = 0.005) and progression-free survival (aHR = 0.26, 95% CI: 0.10-0.66, p = 0.005). However, in the MAC subgroup, there were no statistically significant differences between those receiving and not receiving TBI. In the setting of RIC in UCBT, TBI utilization can improve overall survival and progression-free survival. However, TBI does not show superiority in the MAC setting.