Human Umbilical Cord Blood-derived CD34 Research Articles

Metabolic sensor O-GlcNAcylation regulates erythroid differentiation and globin production via BCL11A

BackgroundHuman erythropoiesis is a tightly regulated, multistep process encompassing the differentiation of hematopoietic stem cells (HSCs) toward mature erythrocytes. Cellular metabolism is an important regulator of cell fate determination during the differentiation of HSCs. However, how O-GlcNAcylation, a posttranslational modification of proteins that is an ideal metabolic sensor, contributes to the commitment of HSCs to the erythroid lineage and to the terminal erythroid differentiation has not been addressed.MethodsCellular O-GlcNAcylation was manipulated using small molecule inhibition or CRISPR/Cas9 manipulation of catalyzing enzyme O-GlcNAc transferase (OGT) and removing enzyme O-GlcNAcase (OGA) in two cell models of erythroid differentiation, starting from: (i) human umbilical cord blood-derived CD34+ hematopoietic stem/progenitor cells (HSPCs) to investigate the erythroid lineage specification and differentiation; and (ii) human-derived erythroblastic leukemia K562 cells to investigate the terminal differentiation. The functional and regulatory roles of O-GlcNAcylation in erythroid differentiation, maturation, and globin production were investigated, and downstream signaling was delineated.ResultsFirst, we observed that two-step inhibition of OGT and OGA, which were established from the observed dynamics of O-GlcNAc level along the course of differentiation, promotes HSPCs toward erythroid differentiation and enucleation, in agreement with an upregulation of a multitude of erythroid-associated genes. Further studies in the efficient K562 model of erythroid differentiation confirmed that OGA inhibition and subsequent hyper-O-GlcNAcylation enhance terminal erythroid differentiation and affect globin production. Mechanistically, we found that BCL11A is a key mediator of O-GlcNAc-driven erythroid differentiation and β- and α-globin production herein. Additionally, analysis of biochemical contents using synchrotron-based Fourier transform infrared (FTIR) spectroscopy showed unique metabolic fingerprints upon OGA inhibition during erythroid differentiation, supporting that metabolic reprogramming plays a part in this process.ConclusionsThe evidence presented here demonstrated the novel regulatory role of O-GlcNAc/BCL11A axis in erythroid differentiation, maturation, and globin production that could be important in understanding erythropoiesis and hematologic disorders whose etiology is related to impaired erythroid differentiation and hemoglobinopathies. Our findings may lay the groundwork for future clinical applications toward an ex vivo production of functional human reticulocytes for transfusion from renewable cell sources, i.e., HSPCs and pluripotent stem cells.

Abstract 1639: Human immune system mouse model of ER+ metastatic breast cancer

Abstract In a recent clinical trial in heavily pretreated estrogen receptor alpha-positive (ER+) metastatic breast cancer (MBC), ~23% of patients reached the primary endpoint of clinical benefit of >24 weeks on Fulvestrant plus the anti-androgen Enzalutamide. ESR1 mutant biopsies had more T regulatory cells (t test p<0.021) and macrophages (p<0.003) than ESR1 wild type (WT), which had more TP53 mutations and higher levels of cytotoxic T effector cells (p<0.01). In addition, PD-L1 increased in post- vs. pre-treatment biopsies (paired t test p<0.002). This increase in PD-L1 post-treatment warrants testing if the addition of a checkpoint inhibitor to the Fulvestrant-Enzalutamide combination will enhance therapy efficacy in ER+ MBC resistant to standard endocrine therapy. However, the lack of immune competent ER+ breast cancer pre-clinical models is a major barrier to these studies. Human immune system (HIS) mouse models were developed as a platform in which to test immune checkpoint inhibitors in other human cancers, and one HIS model was recently shown to support the growth and immune infiltration of ER+ patient-derived xenograft (PDX) primary tumors. We tested whether HIS mice are a robust model in which to define ER+ tumor-immune microenvironment interactions at metastatic sites. We implanted NCG mice (NOD-Prkdcem26Cd52Il2rgem26Cd22/NjuCrl) humanized by engraftment of human umbilical cord blood-derived CD34+ (huCD34+) stem cells with the estrogen-independent HCI-013EI (013EI) PDX, derived from an ER+, invasive lobular MBC which harbors the Y537S ESR1 mutation. Mice were monitored for tumor latency and growth rate, and primary tumors and organs were collected for immunohistochemistry, single-cell RNA sequencing (scRNAseq), and phasor-fluorescence lifetime imaging microscopy (FLIM). The ER mutated PDX 013EI had a longer tumor latency in HIS (median 77 days) vs. age-matched immune deficient control mice (27.5 days, log-rank p=0.043). Once formed, 013EI tumors in HIS mice grew slower than those in controls (mixed-effects analysis, p=0.035). HIS mice had visible lung, liver, and/or gastrointestinal tract metastases despite small primary tumors. Lung metastases from HIS mice retain ER expression and are infiltrated by human CD4+, CD8+, and CD68+ immune cells. Initial scRNAseq analysis also suggests infiltration by diverse immune cell populations in primary tumors from HIS mice. Initial phasor-FLIM for NADH autofluorescence suggests that 013EI tumors are highly glycolytic in HIS mice. In conclusion, our results show that huCD34+ HIS mice effectively support growth, metastasis, and immune infiltration of an ESR1 mutant MBC PDX. Ongoing studies will further define the tumor-immune microenvironment in this and ESR1 WT MBC PDX, focusing on immune cell infiltration, PD-L1 expression, steroid receptor status, metabolic signaling and changes in these parameters following novel combinations of endocrine, immunotherapy and metabolic agents. Citation Format: Ayodeji Olukoya, Shaymaa Bahnassy, Nicole S. Spoelstra, Lu Jin, Suman Ranjit, Anthony Elias, Jennifer K. Richer, Rebecca B. Riggins. Human immune system mouse model of ER+ metastatic breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1639.

Expression of the Tumor Suppressor WT1 Is Induced By PML-Rara in Acute Promyelocytic Leukemia. Â

Inactivating mutations in Wilms Tumor 1 (WT1) are found in 5-10% of cases of acute myeloid leukemia (AML). Paradoxically, wild type WT1 is expressed highly in most cases of AML compared to normal hematopoietic progenitors, and high levels of WT1 have been associated with poor outcomes. Therefore, it is not yet clear whether loss-of-function WT1 mutations-or paradoxically, wild type WT1 overexpression-both promote disease progression in AML. We performed a genome-wide screen for mutations in acute promyelocytic leukemia (APL), a morphologic subtype of AML characterized by the PML-RARA fusion. We identified WT1 mutations in 11/42 patients, suggesting that WT1 mutations may cooperate specifically with PML-RARA in APL. Further, expression analysis demonstrated a high level of wild type WT1 expression in non-mutated cases. To test the effect of Wt1 inactivation in a mouse model of APL, we bred mice carrying a floxed Wt1 allele (give Baylor reference) to transgenic mice expressing tamoxifen-inducible Cre recombinase (ERT2-Cre). Tamoxifen treatment leads to deletion of the C-terminal zinc finger domains of Wt1, mimicking some of the mutations that are commonly found in AML/APL cases. These mice were crossed with mice expressing the PML-RARA fusion cDNA in early myeloid progenitors with Cathepsin G (Ctsg) regulatory sequences (Ctsg-PML-RARA). Bone marrow cells from Ctsg-PML-RARA x Wt1fl/fl x ERT2-Cre mice were transplanted into irradiated recipients. Tamoxifen-treated mice (i.e. Wt1 deficient) developed APL with a significantly shortened latency compared to untreated controls (198 days vs. endpoint not reached, N=8-10 each group, p=.0001), suggesting that Wt1 loss-of-function mutations can cooperate with PML-RARA to drive APL. Next, to test the effect of wild type Wt1 overexpression on hematopoietic cells, bone marrow cells from wild type or Ctsg-PML-RARA mice was transduced with retroviruses expressing full length Wt1 cDNA or an empty vector control, and subjected to serial replating. As previously reported, untransduced bone marrow cells from Ctsg-PML-RARA mice were able to form colonies in methylcellulose week after week, while cells overexpressing wild type Wt1 were selected against during serial replating, as demonstrated by a gradual reduction in GFP percentage and Wt1 expression, as measured by western blotting. Interestingly, in contrast to human AML/APL, Wt1 expression could not be detected in a panel of murine tumors with initiating mutations in DNMT3A, PML-RARA, or MLL-AF9 . Taken together, these findings suggest that Wt1 expression suppresses APL development in mice.To reconcile these findings with the high level of WT1 expression in human AML/APL, we speculated that in human progenitor cells, WT1 expression may be induced by leukemia-associated oncogenes (like PML-RARA) as a physiologic, inhibitory response to oncogenic stress. In this case, subsequent inactivating mutations in WT1 would provide an additional growth advantage. Given the observed interspecies difference between WT1/Wt1 expression levels in mouse and human leukemia cells, we used human umbilical cord blood-derived CD34+ cells transduced with retroviruses expressing PML-RARA to model early events in human APL development. CD34+ cells expressing PML-RARA share some characteristics of fully transformed APL cells, including enhanced proliferation in liquid culture, and reduced expression of the myeloid maturation markers CD11b and CD14. WT1 mRNA expression is low in freshly isolated CD34+ cells, but rapidly increases in cells expressing PML-RARA over two weeks in culture (10.5-fold increase compared to empty-vector transduced controls, N=3 separate experiments, p<0.05). Western blotting confirmed robust induction of WT1 protein in transformed cells compared to empty-vector transduced controls, suggesting that WT1 expression is a normal consequence of PML-RARA activation in human hematopoietic progenitor cells. In summary, these findings support a cooperating role for WT1 mutations in APL development, and a potential mechanism to explain the high level of wild type WT1 expression observed in APL cells. Further experiments will be required to determine the downstream mechanisms by which WT1 antagonizes APL development, and whether these observations are generalizable to other AML subtypes. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

The opposing roles of the mTOR signaling pathway in different phases of human umbilical cord blood-derived CD34+ cell erythropoiesis

As an indispensable, even lifesaving practice, red blood cell (RBC) transfusion is challenging due to several issues, including supply shortage, immune incompatibility, and blood‐borne infections since donated blood is the only source of RBCs. Although large‐scale in vitro production of functional RBCs from human stem cells is a promising alternative, so far, no such system has been reported to produce clinically transfusable RBCs due to the poor understanding of mechanisms of human erythropoiesis, which is essential for the optimization of in vitro erythrocyte generation system. We previously reported that inhibition of mammalian target of rapamycin (mTOR) signaling significantly decreased the percentage of erythroid progenitor cells in the bone marrow of wild‐type mice. In contrast, rapamycin treatment remarkably improved terminal maturation of erythroblasts and anemia in a mouse model of β‐thalassemia. In the present study, we investigated the effect of mTOR inhibition with rapamycin from different time points on human umbilical cord blood‐derived CD34+ cell erythropoiesis in vitro and the underlying mechanisms. Our data showed that rapamycin treatment significantly suppressed erythroid colony formation in the commitment/proliferation phase of erythropoiesis through inhibition of cell‐cycle progression and proliferation. In contrast, during the maturation phase of erythropoiesis, mTOR inhibition dramatically promoted enucleation and mitochondrial clearance by enhancing autophagy. Collectively, our results suggest contrasting roles for mTOR in regulating different phases of human erythropoiesis.

Generation of Acute Hind Limb Ischemia in NOD/SCID Mice and Treatment with Nanofiber-Expanded CD34+ Hematopoietic Stem Cells.

Critical limb ischemia (CLI) is primarily associated with a high risk of major amputation, cardiovascular events, and death. The current therapy involves direct endovascular intervention and is associated with long-term recurrence. However, patients with significant comorbidities are not eligible for this therapy. Hind limb ischemia model via femoral artery excision has commonly been used to determine therapeutic potential and for investigating cellular and molecular mechanisms. This protocol describes the ischemic model development in NOD/SCID mice and the use of human umbilical cord blood-derived and nanofiber scaffold-expanded CD34+ stem cells to investigate the efficacy of regenerative therapy.

Efficient Ex Vivo Expansion of Highly Purified Human Umbilical Cord Blood-Derived Very Small CD34+lin-CD45- Stem Cells into Functional Endothelial Cells in Vitro in Chemically Identified, Feeder Layer-Free Medium Supplemented with Nicotinamide

Background . There is an ongoing search for multipotent stem cells from umbilical cord blood (UCB) with trans-germ layer differentiation potential that can be employed in repairing damaged organs and also expanded into transplantable hematopoietic stem cells (HSCs) and endothelial progenitor cells (EPCs). The existence of such cells in postnatal life could also revive the concept of hemangioblasts or hemangioblast-like cells in adult hematopoietic organs. Our group was the first to isolate a population of small CD34+CD133+lin-CD45- early-development stem cells from human hematopoietic tissues, including UCB. Based on the validated expression of early-development markers, these cells were named "very small embryonic-like stem cells" (VSELs, Circulation Res 2019; 124:208-210). Currently, more than 25 independent groups worldwide who have carefully followed the multicolor-staining cell-sorting strategy described by us (Current Protocols in Cytometry 2010, 9.29.1-9.29.15) have successfully isolated these cells and demonstrated their in vivo contribution to all three germ layer lineages. Thus, VSELs could be very useful in regenerative medicine in the field of angiogenesis, and UCB is an attractive source, with easy accessibility and tolerance to allogenic grafts. However, the low number of these cells in UCB and their quiescence are limiting factors. Therefore, in vitro differentiation of VSELs into endothelial progenitor cells (EPCs) would allow improvement in the ability to expand endothelial cells and could represent a clinically relevant alternative to embryonic stem cells (ESCs) and induced pluripotent stem cells (iPS) for cell therapy without ethical problems and undesirable side effects. Hypothesis. We hypothesized that UCB-purified, very small, early-developmentCD34+lin-CD45-stem cells can be ex vivo expanded into functional EPCs. Materials and Methods. VSELs highly purified by FACS were expanded into EPCs in pro-angiogenic medium supplemented with mesodermic differentiation factors and then endothelial differentiation factors in the presence of nicotinamide and UM171. In parallel, we expanded EPCs from MNCs isolated from the same UCB units by employing a classical protocol (Methods in Enzymology 2008, 445:303-29). The EPC nature of the expanded VSEL-derived cells was confirmed by the expression of typical EPC markers as well as by in vitro angiogenic assays. Results. Our differentiation cocktail allowed us to differentiate and expand VSELs into EPCs. In our expansion medium (Figure 1), the very small, round VSELs smaller than 6 mm in diameter proliferated and differentaited over time into larger and extended cells with a cobblestone morphology similar to the EPC control cells, and we confirmed their endothelial characteristics by cytometry analysis. Like EPCs, VSEL-derived EPCs were positive for CD31, CD144, KDR, and CD105 and negative for mesenchymal surface markers, such as CD90. They also performed similarly to EPCs in classical vasculogenic tests, including adhesion, proliferation, migration, and tubulogenesis assays. Conclusions. This work shows, for the first time, efficient VSEL differentiation into functional endothelial cells with vasculogenic properties without the help of co-culture over feeder-layers or viral vectors in medium supplemented with nicotinamide and UM171. These findings allow us to propose these cells as an interesting cell therapy product. These results also reopen the question of the existence of hemangioblast-like cells in postnatal tissues. We are currently testing these cells in vivo in model of hind limb ischemia. Figure 1 Disclosures No relevant conflicts of interest to declare.

Nanofiber-expanded human CD34+ cells heal cutaneous wounds in streptozotocin-induced diabetic mice

Despite advances in diabetic wound care, the significant number of amputations that occur every year demands more effective therapeutics. Herein, we offer an aminated polyethersulfone nanofiber-expanded human umbilical cord blood-derived CD34+ cells (henceforth CD34+ cells) effective therapy, tested in cutaneous wounds developed in streptozotocin-induced diabetic NOD/SCID mice. We show that systemic administration of CD34+ cells homed to the wound site and significantly accelerated wound closure. Wound closure was associated with improved re-epithelialization and increased neovascularization; and with decreased sustained pro-inflammatory activity of NF-κB and its downstream effector molecules TNF-α, IL-1β, and IL-6 at the wound bed. This finding was further supported by the observation of a decreased number of myeloperoxidase positive neutrophils, and concomitantly increased levels of IL-10. In addition, improved granulation tissue formation was observed along with higher collagen deposition and myofibroblasts and decreased expressions of MMP-1. Mechanistically, CD34+ cells reduced the level of MMP-1 expression by inhibiting recruitment of NF-κB to the MMP-1 promoter site in dermal fibroblasts. In summary, we provide evidence of a novel nanofiber-expanded CD34+ stem cell therapeutic development for treating diabetic wounds by defining their cellular and molecular mechanisms.

AMPK Regulates the Expression of the Fe-S Cluster Assembly Enzyme (ISCU) and ALAS2, Modulating Cellular Iron Metabolism and Increasing Hemoglobin Synthesis

Iron-sulfur (Fe-S) clusters are iron-containing prosthetic groups and enzymatic cofactors. They are strong oxidants when unbound yet essential in many processes like facilitating ATP production in mitochondria, promoting DNA, RNA and protein syntheses during cell proliferation and enhancing DNA repair in antioxidant defense. In particular, Fe-S clusters are indispensable in erythropoiesis, where the majority of physiological iron is utilized and where Fe-S clusters are required for the heme synthesis. Deficient Fe-S cluster synthesis predisposes individual to various diseases, such as cancer, metabolic and neurodegeneration diseases and blood disorders. However, it is unclear how Fe-S cluster synthesis is regulated and coordinates with environmental and developmental needs to prevent oxidative damage.The 5' AMP-activated protein kinase (AMPK) is a kinase activated by oxidative stress and energy starvation and critical for maintaining redox and energy homeostasis. In this study, we investigated the role of AMPK on Fe-S clusters synthesis and function and extended our findings in normal and thalassemic erythroid cells.Through bioinformatic analysis, we found that the Fe-S cluster assembly enzyme (ISCU), a scaffold protein indispensable for Fe-S cluster biogenesis, contains putative AMPK phosphorylation motifs at serine (S) residues 14 and 29 (human numbering). Using the human cell line 293T, we confirmed that AMPK phosphorylates ISCU, while point mutations in these residues prevented this activity. Moreover, AMPK-mediated phosphorylation promoted ISCU binding to 14-3-3s, a family of proteins that, once associate with phosphorylated residues, modulates the stability and function of targeted proteins. Indeed, increased association with 14-3-3s stabilized ISCU proteins, corroborating the observation that AMPK promotes the activity of ISCU proteins.We extended our studies using A549 cells that do not have AMPK activity since they harbor a mutant LKB1 kinase, which is responsible for activating AMPK. By overexpression of wild type (WT)-LKB1 and LKB1 kinase-dead mutant (KDM), we found that only WT-LKB1 restored AMPK activity, binding of ISCU to 14-3-3s and stability of ISCU. Moreover, under hydrogen peroxide incubation and glucose starvation, ISCU protein levels and Fe-S cluster synthesis were both increased only in the presence of LKB1-WT, but not in cells harboring KMD. LKB1-WT overexpressed cells also survived hydrogen peroxide incubation and glucose starvation better than those with KMD. Together, these data suggest that AMPK activation stabilizes ISCU protein and preserves Fe-S cluster synthesis to maintain a healthy redox and energy homeostasis.We then explored the effect of AMPK on Fe-S cluster synthesis in erythropoiesis by using the drug AICAR, an AMPK activator, in murine erythroleukemia (MEL) cells. We found that in MEL cells, AICAR treatment stabilized ISCU, increased Fe-S cluster levels and promoted the synthesis of the aminolevulinic acid synthase 2 (ALAS2) protein, which represents the rate-limiting enzyme in erythroid heme synthesis. Furthermore, this was associated with increased heme and globin chain synthesis, with a trend in increasing β-globin mRNA and proteins more than α-globin. We further confirmed these observations in Human Umbilical Cord Blood-Derived Erythroid Progenitor (HUDEP-2) and CD34+ cells derived from peripheral blood isolated from both healthy individuals and ß-thalassemic patients. In these cells, we found that AMPK upregulation by AICAR administration not only increased ALAS2 expression and erythroid heme levels, but also enhanced the synthesis of both a- and ß-globin chains, though with a preference for increasing β-globin levels. Analysis using specimens from thalassemic mice is in progress.In conclusion, our work demonstrates that under redox and energetic stress, activated AMPK phosphorylates and stabilizes ISCU protein, thereby enhancing Fe-S cluster synthesis and maintaining their function. Moreover, AMPK activation with AICAR treatment increases erythroid heme synthesis and hemoglobin expression. Given that AMPK is the major kinase that responds to oxidative and energetic cues, our work provides a mechanistic explanation for how erythropoiesis responds to energy starvation and redox stress as well as a potential novel therapeutic target to treat blood and metabolic disorders. DisclosuresRivella:Ionis Pharmaceuticals, Inc: Consultancy; MeiraGTx: Other: SAB; Protagonist: Consultancy; Disc Medicine: Consultancy.

The Effect of Vascular Graft and Human Umbilical Cord Blood-Derived CD34+ Stem Cell on Peripheral Nerve Healing.

AIM:There are many trials concerning peripheral nerve damage causes and treatment options. Unfortunately, nerve damage is still a major problem regarding health, social and economic issues. On this study, we used vascular graft and human cord blood derived stem cells to find an alternative treatment solution to this problem.MATERIAL AND METHODS:We used 21 female Wistar rats on our study. They were anesthetized with ketamine and we studied right hind limbs. On Group 1, we did a full layer cut on the right sciatic nerve. On Group 2, we did a full layer cut on the right sciatic nerve, and we covered synthetic vascular graft on cut area. On Group 3, we did a full layer cut on right sciatic nerve, and we covered the area with stem cell applied vascular graft.RESULTS:At the end of postoperative 8. weeks, we performed EMG on the rats. When we compared healthy and degenerated areas as a result of EMG, we found significant amplitude differences between the groups on healthy areas whereas there was no significant difference on degenerated areas between the groups. Then we re-opened the operated area again to reveal the sciatic nerve cut area, and we performed electron microscope evaluation. On the stem cell group, we observed that both the axon and the myelin sheet prevented degeneration.CONCLUSION:This study is a first on using synthetic vascular graft and cord blood derived CD34+ cells in peripheral nerve degeneration. On the tissues that were examined with electron microscope, we observed that CD34+ cells prevented both axonal and myelin sheath degeneration. Nerve tissue showed similar results to the control group, and the damage was minimal.

Angelica sinensis Polysaccharides Ameliorate Stress-Induced Premature Senescence of Hematopoietic Cell via Protecting Bone Marrow Stromal Cells from Oxidative Injuries Caused by 5-Fluorouracil.

Myelosuppression is the most common complication of chemotherapy. Decline of self-renewal capacity and stress-induced premature senescence (SIPS) of hematopoietic stem cells (HSCs) induced by chemotherapeutic agents may be the cause of long-term myelosuppression after chemotherapy. Whether the mechanism of SIPS of hematopoietic cells relates to chemotherapeutic injury occurred in hematopoietic microenvironment (HM) is still not well elucidated. This study explored the protective effect of Angelica sinensis polysaccharide (ASP), an acetone extract polysaccharide found as the major effective ingredients of a traditional Chinese medicinal herb named Chinese Angelica (Dong Quai), on oxidative damage of homo sapiens bone marrow/stroma cell line (HS-5) caused by 5-fluorouracil (5-FU), and the effect of ASP relieving oxidative stress in HM on SIPS of hematopoietic cells. Tumor-suppressive doses of 5-FU inhibited the growth of HS-5 in a dose-dependent and time-dependent manner. 5-FU induced HS-5 apoptosis and also accumulated cellular hallmarks of senescence including cell cycle arrest and typical senescence-associated β-galactosidase positive staining. The intracellular reactive oxygen species (ROS) was increased in 5-FU treated HS-5 cells and coinstantaneous with attenuated antioxidant capacity marked by superoxide dismutase and glutathione peroxidase. Oxidative stress initiated DNA damage indicated by increased γH2AX and 8-OHdG. Oxidative damage of HS-5 cells resulted in declined hematopoietic stimulating factors including stem cell factor (SCF), stromal cell-derived factor (SDF), and granulocyte-macrophage colony-stimulating factor (GM-CSF), however, elevated inflammatory chemokines such as RANTES. In addition, gap junction channel protein expression and mediated intercellular communications were attenuated after 5-FU treatment. Significantly, co-culture on 5-FU treated HS-5 feeder layer resulted in less quantity of human umbilical cord blood-derived hematopoietic cells and CD34+ hematopoietic stem/progenitor cells (HSPCs), and SIPS of hematopoietic cells. However, it is noteworthy that ASP ameliorated SIPS of hematopoietic cells by the mechanism of protecting bone marrow stromal cells from chemotherapeutic injury via mitigating oxidative damage of stromal cells and improving their hematopoietic function. This study provides a new strategy to alleviate the complication of conventional cancer therapy using chemotherapeutic agents.

Control of HIV Infection InVivo Using Gene Therapy with a Secreted Entry Inhibitor.

HIV entry inhibitors are highly effective in controlling virus replication. We have developed a lentiviral vector that expresses a secreted entry inhibitor, soluble CD4 (sCD4), which binds to the HIV envelope glycoproteins and inactivates the virus. We have shown that sCD4 was secreted from gene-modified CD4+ T cells, as well as from human umbilical cord blood-derived CD34+ hematopoietic stem/progenitor cells (HSPCs), and protected unmodified HIV target cells from infection in vitro. To investigate the in vivo application of our approach, we injected gene-modified HSPCs into NOD/SCID/γcnull (NSG) mice. NSG hosts supported multi-lineage differentiation of human gene-modified HSPCs. Upon challenge with HIV, humanized mice capable of secreting sCD4 demonstrated a reduction of viral load over time compared to control humanized mice. In contrast to gene therapy approaches that render only gene-modified HIV target cells resistant to infection, our approach also showed protection of unmodified CD4+ T cells in the peripheral blood and tissues. Our findings provide support for the continuous delivery of secreted entry inhibitors via gene therapy as an alternative to oral administration of antiretroviral drugs or injection of antiretroviral proteins, including antibodies.

Effect of umbilical cord blood stem cells transplantation on bladder dysfunction induced by cerebral ischemia in rats

ObjectiveTo demonstrate the effect of human umbilical cord blood-derived CD34+ cells on bladder dysfunction induced by cerebral ischemia in rats. Materials and MethodsFemale rats were subjected to either 60 minute middle cerebral artery occlusion (MCAO) or a sham operation. Rats were divided into four groups: sham operation, MCAO without treatment, infusion with 1×106 CD34+ cells 30 minutes before MCAO, and infusion with 1×106 CD34+ cells 3 hours after MCAO. Bladder function was analyzed by cystometry at 1 day, 3 days, and 7 days after MCAO. Expressions of nerve growth factor (NGF), M2 and M3 muscarinic receptors were measured by immunohistochemistry and real time polymerase chain reaction. ResultsCystometric results showed that, following MCAO, rats have a significant increase in peak voiding pressure and residual volume. Conversely, there is a significant decrease in voided volumes and intercontraction intervals. Cystometric variables after pre- and postischemic CD34+ treatment nearly returned to levels found in sham-operated rats. The expression of bladder NGF and M3 was decreased after MCAO, but significantly increased following preischemic CD34+ treatment. There was decreased expression of bladder M2 mRNA despite an increased level of M2 immunoreactivity at 3 days and 7 days after MCAO. Expression of bladder M2 immunoreactivity and mRNA nearly returned to sham group levels after preischemic CD34+ treatment. ConclusionBladder dysfunction in a rat model caused by MCAO may be restored to normal micturition by treatment with human umbilical cord blood-derived CD34+ cells and may be related to the expressions of NGF, M2, and M3 in the bladder.

Osteoblasts secrete miRNA-containing extracellular vesicles that enhance expansion of human umbilical cord blood cells.

Osteolineage cells represent one of the critical bone marrow niche components that support maintenance of hematopoietic stem and progenitor cells (HSPCs). Recent studies demonstrate that extracellular vesicles (EVs) regulate stem cell development via horizontal transfer of bioactive cargo, including microRNAs (miRNAs). Using next-generation sequencing we show that human osteoblast-derived EVs contain highly abundant miRNAs specifically enriched in EVs, including critical regulators of hematopoietic proliferation (e.g., miR-29a). EV treatment of human umbilical cord blood-derived CD34+ HSPCs alters the expression of candidate miRNA targets, such as HBP1, BCL2 and PTEN. Furthermore, EVs enhance proliferation of CD34+ cells and their immature subsets in growth factor-driven ex vivo expansion cultures. Importantly, EV-expanded cells retain their differentiation capacity in vitro and successfully engraft in vivo. These discoveries reveal a novel osteoblast-derived EV-mediated mechanism for regulation of HSPC proliferation and warrant consideration of EV-miRNAs for the development of expansion strategies to treat hematological disorders.

Direct bone marrow HSC transplantation enhances local engraftment at the expense of systemic engraftment in NSG mice.

Direct bone marrow (BM) injection has been proposed as a strategy to bypass homing inefficiencies associated with intravenous (IV) hematopoietic stem cell (HSC) transplantation. Despite physical delivery into the BM cavity, many donor cells are rapidly redistributed by vascular perfusion, perhaps compromising efficacy. Anchoring donor cells to 3-dimensional (3D) multicellular spheroids, formed from mesenchymal stem/stromal cells (MSC) might improve direct BM transplantation. To test this hypothesis, relevant combinations of human umbilical cord blood-derived CD34+ cells and BM-derived MSC were transplanted into NOD/SCID gamma (NSG) mice using either IV or intrafemoral (IF) routes. IF transplantation resulted in higher human CD45+ and CD34+ cell engraftment within injected femurs relative to distal femurs regardless of cell combination, but did not improve overall CD45+ engraftment at 8 weeks. Analysis within individual mice revealed that despite engraftment reaching near saturation within the injected femur, engraftment at distal hematopoietic sites including peripheral blood, spleen and non-injected femur, could be poor. Our data suggest that the retention of human HSC within the BM following direct BM injection enhances local chimerism at the expense of systemic chimerism in this xenogeneic model.

Effect of Stem Cell Therapy on Bone Mineral Density: A Meta-Analysis of Preclinical Studies in Animal Models of Osteoporosis.

BackgroundPreclinical studies of the therapeutic role of stem cell based therapy in animal models of osteoporosis have largely yielded inconsistent results. We performed a meta-analysis to provide an overview of the currently available evidence.MethodsPubmed, Embase and Cochrane Library databases were systematically searched for relevant controlled studies. A random-effect model was used for pooled analysis of the effect of stem cell based therapy on bone mineral density (BMD). Stratified analyses were performed to explore the effect of study characteristics on the outcomes.ResultsPooled results from 12 preclinical studies (110 animals in stem cell treatment groups, and 106 animals in control groups) indicated that stem cell based treatment was associated with significantly improved BMD (standardized mean difference [SMD] = 1.29, 95% Confidence Interval [CI]: 0.84–1.74, P < 0.001) with moderate heterogeneity (Cochrane’s Q test: P = 0.02, I2 = 45%) among the constituent studies. Implantation of bone marrow cells, bone marrow mesenchymal stem cells, adipose-derived stem cells, and human umbilical cord blood-derived CD34+ cells, were all associated with improved BMD as compared to that in the controls (P < 0.05 for all); the only exception being the use of embryonic stem cell transplantation (P > 0.05). Egger’s test detected potential publication bias (P = 0.055); however, ‘trim and fill’ analysis yielded similar results after statistically incorporating the hypothetical studies in the analysis (SMD = 1.24, 95% CI: 0.32–2.16, P < 0.001).ConclusionsStem cell transplantation may improve BMD in animal models of osteoporosis. Our meta-analysis indicates a potential therapeutic role of stem cell based therapy for osteoporosis, and serves to augment the rationale for clinical studies.

Attenuating spinal cord injury by conditioned medium from human umbilical cord blood-derived CD34+ cells in rats

ObjectiveIntravenous or intraspinal transplantation of human umbilical cord blood cells-derived CD34+ cells (human CD34+ cells) or mesenchymal stem cells after spinal cord injury (SCI) improved hind limb functional recovery in adult rats. The objective of this study is to ascertain whether SCI in rats can be attenuated by conditioned medium (CM) or secretome obtained from cultured human CD34+ stem cells. Materials and methodsSprague-Dawley rats were assigned to one of the following five groups: the sham group, the SCI group treated with vehicle solution (SCI + V), the SCI group treated with CM (SCI + CM), the SCI group treated with 17β-estradiol E2 (10 μg; SCI + E2), and the SCI group treated with CM plus E2 (SCI + CM + E2). A 0.5-mL volume of CM or vehicle solution was administered intravenously immediately after SCI. ResultsCompared with the sham group, the (SCI + V) group had significantly higher scores of neurological motor dysfunction as well as inflammation apoptosis, oxidative stress, and astrogliosis in the injured spinal cord. The neurological deficits, numbers of apoptotic cell, extent of inflammation, oxidative stress, and astrogliosis in the injured spinal cord were significantly attenuated by CM, E2, or CM plus E2, but not by the vehicle solution. In addition, the neuroprotective effect exerted by a combination of CM and E2 is superior to that exerted by CM- or E2-alone therapy. ConclusionThe neuroprotective effects of CM from cultured human CD34+ cells are similar to those of human CD34+ cells and the CM was found to enhance the neuroprotective effects of E2 in rat SCI.

Lysophosphatidic acid enhances survival of human CD34(+) cells in ischemic conditions.

Several clinical trials are exploring therapeutic effect of human CD34+ cells in ischemic diseases, including myocardial infarction. Unfortunately, most of the cells die few days after delivery. Herein we show that lysophosphatidic acid (LPA)-treated human umbilical cord blood-derived CD34+ cells cultured under hypoxic and serum-deprived conditions present 2.2-fold and 1.3-fold higher survival relatively to non-treated cells and prostaglandin E2-treated cells, respectively. The pro-survival effect of LPA is concentration- and time-dependent and it is mediated by the activation of peroxisome proliferator-activator receptor γ (PPARγ) and downstream, by the activation of pro-survival ERK and Akt signaling pathways and the inhibition of mitochondrial apoptotic pathway. In hypoxia and serum-deprived culture conditions, LPA induces CD34+ cell proliferation without maintaining the their undifferentiating state, and enhances IL-8, IL-6 and G-CSF secretion during the first 12 h compared to non-treated cells. LPA-treated CD34+ cells delivered in fibrin gels have enhanced survival and improved cardiac fractional shortening at 2 weeks on rat infarcted hearts as compared to hearts treated with placebo. We have developed a new platform to enhance the survival of CD34+ cells using a natural and cost-effective ligand and demonstrated its utility in the preservation of the functionality of the heart after infarction.

Differential Promoter Usage and Regulation Of The Human Interleukin-5 Receptor α (IL-5Rα) Gene In Developing Eosinophil Progenitors

IL-5Rα is a critical component of the IL-5 signaling pathway responsible for regulating the expansion of the eosinophil lineage for development of eosinophilia in allergic diseases, including asthma. IL-5Rα has two promoters, P1 and P2, both functionally active in eosinophilic cell lines. However, their differential roles and regulation during the development of authentic eosinophil progenitors remain unexplored. Human umbilical cord blood-derived CD34+progenitors under IL-5-induced eosinophil differentiation were transfected with IL-5Rα-P1 or -P2 promoter luciferase reporter vectors at various time points to assess their differential promoter activity. Chromatin immunoprecipitation (ChIP) was performed at corresponding time points to determine the dynamic occupancy of these promoters by transcription factors implicated in IL-5Rα regulation during eosinophil development. The IL-5Rα-P1 promoter is active throughout IL-5-induced eosinophil differentiation of CD34+/IL-5Rα+progenitors. However, P2 promoter activity is suddenly induced on day 7, overtaking P1 activity, before being attenuated during continued eosinophil development. Peak P2 activity coincides with a dramatic induction in expression of the predominant soluble IL-5Rα isoform mRNA. Correspondingly, quantitative ChIPs revealed that the two promoters exhibit differential occupancy by transcription factors GATA-1, PU.1 and/or the C/EBP family of transcription factors (α, β and ε). Human IL-5Rα-P1 and -P2 promoters are under differential regulation, mediated in part through dynamic and combinatorial interactions of stage-specific transcription factors. The coincidental peak in P2 promoter activity and IL-5Rα soluble isoform mRNA suggest that the IL-5-binding soluble receptor isoform is induced during eosinophil development to regulate or prevent excessive expansion of the eosinophil lineage in parasitic and allergic diseases.

Umbilical Cord Blood-Derived Stem Cells Improve Heat Tolerance and Hypothalamic Damage in Heat Stressed Mice

Heatstroke is characterized by excessive hyperthermia associated with systemic inflammatory responses, which leads to multiple organ failure, in which brain disorders predominate. This definition can be almost fulfilled by a mouse model of heatstroke used in the present study. Unanesthetized mice were exposed to whole body heating (41.2°C for 1 hour) and then returned to room temperature (26°C) for recovery. Immediately after termination of whole body heating, heated mice displayed excessive hyperthermia (body core temperature ~42.5°C). Four hours after termination of heat stress, heated mice displayed (i) systemic inflammation; (ii) ischemic, hypoxic, and oxidative damage to the hypothalamus; (iii) hypothalamo-pituitary-adrenocortical axis impairment (reflected by plasma levels of both adrenocorticotrophic-hormone and corticosterone); (iv) decreased fractional survival; and (v) thermoregulatory deficits (e.g., they became hypothermia when they were exposed to room temperature). These heatstroke reactions can be significantly attenuated by human umbilical cord blood-derived CD34+ cells therapy. Our data suggest that human umbilical cord blood-derived stem cells therapy may improve outcomes of heatstroke in mice by reducing systemic inflammation as well as hypothalamo-pituitary-adrenocortical axis impairment.

Human Umbilical Cord Blood-Derived CD34-Positive Endothelial Progenitor Cells Stimulate Osteoblastic Differentiation of Cultured Human Periosteal-Derived Osteoblasts

The aim of this study was to examine the effects of human umbilical cord blood-derived CD34-positive endothelial progenitor cells (CD34+ EPCs) on osteoblastic differentiation of cultured human periosteal-derived osteoblasts (POs). CD34+ cells from human umbilical cord blood were sorted to purify more EPCs in characterization. These sorted cells showed CD31, VE-cadherin, and KDR expression as well as CD34 expression and formed typical tubes in Matrigel. These sorted cells were referred to as human cord blood-derived CD34+ EPCs. In in vivo bone formation using a miniature pig model, the newly formed bone was clearly examined in defects filled with polydioxanone/pluronic F127 (PDO/Pluronic F127) scaffolds containing either human umbilical cord blood-derived CD34+ EPCs and POs or human umbilical vein endothelial cells (HUVEC) and POs; however, the new bone had the greatest density in the defect treated with CD34+ EPCs and POs. Osteoblastic phenotypes of cultured human POs using ALP activity and von Kossa staining were also more clearly found in CD34+ EPC-conditioned medium than CD34-negative (CD34-) cell-conditioned medium, whereas HUVEC-conditioned medium had an intermediate effect. PCR array for common cytokines and growth factors showed that the secretion of interleukin (IL)-1β was significantly higher in CD34+ EPCs than in HUVEC, followed by level in CD34- cells. In addition, IL-1β also potently and dose dependently increased ALP activity and mineralization of POs in culture. These results suggest that human umbilical cord blood-derived CD34+ EPCs stimulates osteoblastic differentiation of cultured human POs. The functional role of human umbilical cord blood-derived CD34+ EPCs in increasing the osteogenic phenotypes of cultured human POs may depend on IL-1β secreted from human umbilical cord blood-derived CD34+ EPCs.