Functional Integrity and Gene Expression Profiles of Human Cord Blood-Derived Hematopoietic Stem and Progenitor Cells Generated In Vitro

Further biological characterization of small molecules UM171 and SR1: In vitro effects on three hematopoietic cell populations from human cord blood

Small molecules UM171 and SR1 have already been taken into clinically-oriented protocols for the ex vivo expansion of hematopoietic stem (HSCs) and progenitor (HPCs) cells. In order to gain further insight into their biology, in the present study we have assessed their effects, both individually and in combination, on the in vitro long-term proliferation and expansion of HSCs and HPCs contained within three different cord blood-derived cell populations: MNCs (CD34+ cells = 0.8 %), LIN- cells (CD34+ cells = 41 %), and CD34+ cells (CD34+ cells >98 %). Our results show that when added to cultures in the absence of recombinant stimulatory cytokines, neither molecule had any effect. In contrast, when added in the presence of hematopoietic cytokines, UM171 and SR1 had significant stimulatory effects on cell proliferation and expansion in cultures of LIN- and CD34+ cells. No significant effects were observed in cultures of MNCs. The effects of both molecules were more pronounced in cultures with the highest proportion of CD34+ cells, and the greatest effects were observed when both molecules were added in combination. In the absence of small molecules, cell numbers reached a peak by days 25-30, and then declined; whereas in the presence of UM171 or/and SR1 cell numbers were sustained up to day 45 of culture. Our results indicate that besides CD34+ cells, LIN- cells could also be used as input cells in clinically-oriented expansion protocols, and that using both molecules simultaneously would be a better approach than using only one of them.

Umbilical Cord Blood Hematopoietic Cells: From Biology to Hematopoietic Transplants and Cellular Therapies

Umbilical cord blood (UCB) is a rich source of hematopoietic stem and progenitor cells that are biologically superior to their adult counterparts. UCB cells can be stored for several years without compromising their numbers or function. Today, public and private UCB banks have been established in several countries around the world. After 35 years since the first UCB transplant (UCBT), more than 50,000 UCBTs have been performed worldwide. In pediatric patients, UCBT is comparable to or superior to bone marrow transplantation. In adult patients, UCB can be an alternative source of hematopoietic cells when an HLA-matched unrelated adult donor is not available and when a transplant is urgently needed. Delayed engraftment (due to reduced absolute numbers of hematopoietic cells) and higher costs have led many medical institutions not to consider UCB as a first-line cell source for hematopoietic transplants. As a result, the use of UCB as a source of hematopoietic stem and progenitor cells for transplantation has declined over the past decade. Several approaches are being investigated to make UCBTs more efficient, including improving the homing capabilities of primitive UCB cells and increasing the number of hematopoietic cells to be infused. Several of these approaches have already been applied in the clinic with promising results. UCB also contains immune effector cells, including monocytes and various lymphocyte subsets, which, together with stem and progenitor cells, are excellent candidates for the development of cellular therapies for hematological and non-hematological diseases.

Genetic engineering meets hematopoietic stem cell biology for next-generation gene therapy

The growing clinical success of hematopoietic stem/progenitor cell (HSPC) gene therapy (GT) relies on the development of viral vectors as portable "Trojan horses" for safe and efficient gene transfer. The recent advent of novel technologies enabling site-specific gene editing is broadening the scope and means of GT, paving the way to more precise genetic engineering and expanding the spectrum of diseases amenable to HSPC-GT. Here, we provide an overview of state-of-the-art and prospective developments of the HSPC-GT field, highlighting how advances in biological characterization and manipulation of HSPCs will enable the design of the next generation of these transforming therapeutics.

Cellular Therapies: Yesterday, Today, and Tomorrow

Cellular therapy (CT) can be defined as the transference into a person of healthy cells to correct defective functions. Yesterday (1950-2010), CT consisted mostly of hematopoietic transplants for the treatment of a variety of hematological disorders. Interestingly, during that period of time other cell types with therapeutic potential-including certain lymphoid populations and other nonhematopoietic cells-were discovered and characterized; thus, CT became a promising discipline for the treatment of a broader diversity of diseases. Today (2011-2023), CT has significantly grownup through preclinical studies and clinical trials, and it is currently progressing toward its consolidation as one of the pillars of medicine in the 21st century. Indeed, different types of stem cells (e.g., hematopoietic, mesenchymal, neural, and pluripotent), as well as different lymphoid and myeloid cell populations (e.g., TILs, CAR-Ts, CAR-NKs, and DUOC-01) are being used in clinical settings or are being tested in clinical trials. For the past decade, several CT modalities have been developed, and today, many of them are being used in the clinic. Tomorrow (2024-2040), already established CT modalities will surely be improved and applied more frequently, and novel therapies (that will include cell types such as iPSCs) will enter and expand within the clinical ground. It is noteworthy, however, that despite significant advancements and achievements, problems still need to be solved and obstacles need to be overcome. Technical, ethical, and economic issues persist and they need to be addressed. Undoubtedly, exciting times of challenges and opportunities are coming ahead in the CT arena.

PLAG1 dampens protein synthesis to promote human hematopoietic stem cell self-renewal

Hematopoietic stem cell (HSC) dormancy is understood as supportive of HSC function and its long-term integrity. Although regulation of stress responses incurred as a result of HSC activation is recognized as important in maintaining stem cell function, little is understood of the preventive machinery present in human HSCs that may serve to resist their activation and promote HSC self-renewal. We demonstrate that the transcription factor PLAG1 is essential for long-term HSC function and, when overexpressed, endows a 15.6-fold enhancement in the frequency of functional HSCs in stimulatory conditions. Genome-wide measures of chromatin occupancy and PLAG1-directed gene expression changes combined with functional measures reveal that PLAG1 dampens protein synthesis, restrains cell growth and division, and enhances survival, with the primitive cell advantages it imparts being attenuated by addition of the potent translation activator, c-MYC. We find PLAG1 capitalizes on multiple regulatory factors to ensure protective diminished protein synthesis including 4EBP1 and translation-targeting miR-127 and does so independently of stress response signaling. Overall, our study identifies PLAG1 as an enforcer of human HSC dormancy and self-renewal through its highly context-specific regulation of protein biosynthesis and classifies PLAG1 among a rare set of bona fide regulators of messenger RNA translation in these cells. Our findings showcase the importance of regulated translation control underlying human HSC physiology, its dysregulation under activating demands, and the potential if its targeting for therapeutic benefit.

Gene expression profiles and cytokine environments determine the in vitro proliferation and expansion capacities of human hematopoietic stem and progenitor cells

OBJECTIVE

The interplay between intrinsic and extrinsic elements involved in the physiology of hematopoietic cells is not completely understood. In the present study, we analyzed the transcriptional profiles of human cord blood-derived hematopoietic stem cells (HSCs), as well as myeloid (MPCs) and erythroid (EPCs) progenitors, and assessed their proliferation and expansion kinetics in vitro.

METHODS

All cell populations were obtained by cell-sorting, and were cultured in liquid cultures supplemented with different cytokine combinations. Their gene expression profiles were determined by RNA microarrays right after cell-sorting, before culture.

RESULTS

HSCs showed the highest proliferation and expansion capacities in culture, and were found to be more closely related, in transcriptional terms, to MPCs than to EPCs. This correlated with the fact that after 30 days, only cultures initiated with HSCs and MPCs were sustained. Expression of cell cycle and cell division-related genes was enriched in EPCs. Such cells showed significantly higher proliferation than MPCs, however, their expansion potential was reduced, so that cultures initiated with EPCs declined after 15 days and became exhausted by day 30. Proliferation and expansion of HSCs and EPCs were higher in the presence of a cytokine combination that favors erythropoiesis, whereas the growth of MPCs was higher under a cytokine combination that favors myelopoiesis.

CONCLUSION

This study shows a correlation between the transcriptional profiles of HSCs, MPCs, and EPCs, and their respective in vitro growth under particular culture conditions. These results may be relevant in the development of ex vivo systems for the expansion of hematopoietic cells for clinical application.

The effects of cannabidiol via TRPV2 channel in chronic myeloid leukemia cells and its combination with imatinib

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by accumulation of immature cells in bone marrow and peripheral blood. Although successful results were obtained with tyrosine kinase inhibitors, several patients showed resistance. For this reason, the identification of new strategies and therapeutic biomarkers represents an attractive goal. The role of transient receptor potential (TRP) ion channels as possible drug targets has been elucidated in different types of cancer. Among natural compounds known to activate TRPs, cannabidiol (CBD) displays anticancer properties. By using FACS analysis, confocal microscopy, gene silencing, and cell growth assay, we demonstrated that CBD, through TRPV2, inhibits cell proliferation and cell cycle in CML cells. It promoted mitochondria dysfunction and mitophagy as shown by mitochondrial mass reduction and up‐regulation of several mitophagy markers. These effects were associated with changes in the expression of octamer‐binding transcription factor 4 and PU.1 markers regulated during cellular differentiation. Interestingly, a synergistic effect by combining CBD with the standard drug imatinib was found and imatinib‐resistant cells remain susceptible to CBD effects. Therefore, the targeting of TRPV2 by using CBD, through the activation of mitophagy and the reduction in stemness, could be a promising strategy to enhance conventional therapy and improve the prognosis of CML patients.

MEK1 activation enhances the ex vivo proliferation of haematopoietic stem/progenitor cell

Haematopoietic stem/progenitor cell (HSPC) integrates intracellular signal network from growth factors (GFs) and utilizes its proliferation feature to generate high yields of transplantable cells upon ex vivo culture. However, the molecular basis for HSPC activation and proliferation is not completely understood. The goal of this study was to investigate proliferation regulator in the downstream of GFs and develop HSPC expansion strategy. Microarray and Ingenuity Pathway Analysis were performed to evaluate differentially expressed genes in cytokine-induced CD34⁺ cells after ex vivo culture. We identified that MEK1 was a potential HSPC proliferation regulator, which represented indispensable roles and MEK1 silence attenuated the proliferation of HSPC. Notably, 500 nM MEK1 agonist, PAF C-16, increased the numbers of phenotypic HSPC and induced cell cycling of HSPC. The PAF C-16 expanded HSPC demonstrated comparative clonal formation ability and secondary expansion capacity compared to the vehicle control. Our results provide insights into regulating the balance between proliferation and commitment of HSPC by targeting the HSPC proliferation-controlling network. This study demonstrates that MEK1 critically regulates HSPC proliferation and cell production in the ex vivo condition for transplantation.

CCL2 associated with CD38 expression during ex vivo expansion in human cord blood-derived hematopoietic stem cells

To date, different experimental strategies have been developed for the ex vivo expansion of human hematopoietic stem cells (HSCs) for clinical applications. However, differences in the genomic function of expanded HSCs under different culture systems remain unclear. In this study, we compared the gene expression profiles of HSCs in ex vivo expanded serum (10% FBS, fetal bovine serum) and serum-free culture systems and analyzed the molecular functions of differentially expressed genes using microarray chips. We identified 839 differentially expressed genes between the two culture systems. These genes were enriched in the TNF -regulated inflammatory pathway in an FBS culture system. In addition, the mRNA expression of CCL2 (C-C motif chemokine ligand 2), TNF (tumor necrosis factor) and FOS (FBJ murine osteosarcoma viral oncogene homolog) was validated by RT-qPCR. Our data revealed that ex vivo expansion of HSCs using the FBS culture system induces an inflammatory response and high CD38 expression, indicating that this system might activate an inflammatory pathway and induce expression of the cancer marker CD38 during ex vivo expansion of HSCs. This study provides a transcriptional profile and new insights into the genomic functions of HSCs under different expanded cultures.

Differentiated Cells Derived from Hematopoietic Stem Cells and Their Applications in Translational Medicine

Hematopoietic stem cells (HSCs) and their development are one of the most widely studied model systems in mammals. In adults, HSCs are predominantly found in the bone marrow, from where they maintain homeostasis. Besides bone marrow and mobilized peripheral blood, cord blood is also being used as an alternate allogenic source of transplantable HSCs. HSCs from both autologous and allogenic sources are being applied for the treatment of various conditions like blood cancers, anemia, etc. HSCs can further differentiate to mature blood cells. Differentiation process of HSCs is being extensively studied so as to obtain a large number of pure populations of various differentiated cells in vitro so that they can be taken up for clinical trials. The ability to generate sufficient quantity of clinical-grade specialized blood cells in vitro would take the field of hematology a step ahead in translational medicine.

Continuous NF-κB pathway inhibition promotes expansion of human phenotypical hematopoietic stem/progenitor cells through metabolism regulation

Hematopoietic stem/progenitor cells (HSPCs) ex vivo expansion is critical in facilitating their widespread clinical application. NF-κB pathway is implicated in the energy homeostasis and metabolic adaptation. To explore the effect of NF-κB pathway on the ex vivo HSPC expansion and metabolism, the 50 nM-1 μM inhibitor of NF-κB pathway TPCA-1 was used to expand cord blood derived CD34⁺ cells in serum-free culture. The expansion folds, function, mitochondrial profile and metabolism of HSPCs were determined. After 10 days of culture with 100 nM TPCA-1, the expansion of total cells， CD34⁺CD38^- cells， and CD34⁺CD38^-CD45RA^-CD90⁺CD49f⁺ cells were significantly increased compared to the cytokine priming alone. Notably, TPCA-1 treatment generated ~ 2-fold greater percentage of CD34⁺EPCR⁺ and CD34⁺CD38^-CD45RA^-CD90⁺CD49f⁺ cells compared to cytokine only conditions. Moreover, TPCA-1 expanded CD34⁺ cells displayed enhanced serial colonies forming potential and secondary expansion capability. NF-κB inhibition increased the expression of self-renewal related genes, while downregulated the expression of mitochondrial biogenesis regulator (Pgc1α) and mitochondrial chaperones and proteases (ClpP, Hsp10, Hsp60). Mitochondrial mass and membrane potential were markedly decreased with TPCA-1 treatment, leading to the reduced mitochondrial reactive oxygen species (ROS) level in HSPCs. NF-κB inhibition displayed augmented glycolysis rate with compromising mitochondrial metabolism. This study demonstrated that NF-κB pathway inhibition improved glycolysis and limited ROS production that promoted the ex vivo expansion and maintenance of functional HSPCs.

Identification of Differentially Expressed Hematopoiesis-associated Genes in Term Low Birth Weight Newborns by Systems Genomics Approach

Background

Low Birth Weight (LBW) (birth weight <2.5 Kg) newborns are associated with a high risk of infection, morbidity and mortality during their perinatal period. Compromised innate immune responses and inefficient hematopoietic differentiation in term LBW newborns led us to evaluate the gene expression status of hematopoiesis.

Materials and Methods

In this study, we compared our microarray datasets of LBW-Normal Birth Weight (NBW) newborns with two reference datasets to identify hematopoietic stem cells genes, and their differential expression in the LBW newborns, by hierarchical clustering algorithm using gplots and RcolorBrewer package in R.

Results

Comparative analysis revealed 108 differentially expressed hematopoiesis genes (DEHGs), of which 79 genes were up-regulated, and 29 genes were down-regulated in LBW newborns compared to their NBW counterparts. Moreover, protein-protein interactions, functional annotation and pathway analysis demonstrated that the up-regulated genes were mainly involved in cell proliferation and differentiation, MAPK signaling and Rho GTPases signaling, and the down-regulated genes were engaged in cell proliferation and regulation, immune system regulation, hematopoietic cell lineage and JAK-STAT pathway. The binding of down-regulated genes (LYZ and GBP1) with growth factor GM-CSF using docking and MD simulation techniques, indicated that GM-CSF has the potential to alleviate the repressed hematopoiesis in the term LBW newborns.

Conclusion

Our study revealed that DEHGs belonged to erythroid and myeloid-specific lineages and may serve as potential targets for improving hematopoiesis in term LBW newborns to help build up their weak immune defense against life-threatening infections.

Autologous cord blood in children with cerebral palsy: a review

The aim of this narrative review is to report on the current knowledge regarding the clinical use of umbilical cord blood (CB) based on articles from PubMed and clinical trials registered on ClinicalTrials.gov. An increasing amount of evidence suggests that CB may be used for both early diagnostics and treatment of cerebral palsy. The acidity of CB and its biochemical parameters, including dozens of cytokines, growth factors, and other metabolites (such as amino acids, acylcarnitines, phosphatidylcholines, succinate, glycerol, 3-hydroxybutyrate, and O-phosphocholine) are predictors of future neurodevelopment. In addition, several clinical studies confirmed the safety and efficacy of CB administration in both autologous and allogeneic models, including a meta-analysis of five clinical trials involving a total of 328 participants. Currently, nine clinical trials assessing the use of autologous umbilical CB in children diagnosed with hypoxic-ischemic encephalopathy or cerebral palsy are in progress. The total population assessed in these trials exceeds 2500 patients.

Cord blood research, banking, and transplantation: achievements, challenges, and perspectives

The first hematopoietic transplant in which umbilical cord blood (UCB) was used as the source of hematopoietic cells was performed in October 1988. Since then, significant achievements have been reported in terms of our understanding of the biology of UCB-derived hematopoietic stem (HSCs) and progenitor (HPCs) cells. Over 40,000 UCB transplants (UCBTs) have been performed, in both children and adults, for the treatment of many different diseases, including hematologic, metabolic, immunologic, neoplastic, and neurologic disorders. In addition, cord blood banking has been developed to the point that around 800,000 units are being stored in public banks and more than 4 million units in private banks worldwide. During these 30 years, research in the UCB field has transformed the hematopoietic transplantation arena. Today, scientific and clinical teams are still working on different ways to improve and expand the use of UCB cells. A major effort has been focused on enhancing engraftment to potentially reduce risk of infection and cost. To that end, we have to understand in detail the molecular mechanisms controlling stem cell self-renewal that may lead to the development of ex vivo systems for HSCs expansion, characterize the mechanisms regulating the homing of HSCs and HPCs, and determine the relative place of UCBTs, as compared to other sources. These challenges will be met by encouraging innovative research on the basic biology of HSCs and HPCs, developing novel clinical trials, and improving UCB banking both in the public and private arenas.