Nicotinamide, a SIRT1 inhibitor, inhibits differentiation and facilitates expansion of hematopoietic progenitor cells with enhanced bone marrow homing and engraftment

Synergistic effect and molecular mechanism of nicotinamide and UM171 in ex vivo expansion of long-term hematopoietic stem cells

Introduction

Several approaches to expand human hematopoietic stem cells (HSCs) have been reported, but the ability of these methods to expand long-term hematopoietic stem cells (LT-HSCs) remains to be improved, which limits the application of HSCs-based therapies.

Methods

CD34+ cells were purified from umbilical cord blood using MacsCD34 beads, and then cultured for 12 d in a serum-free medium. Flow cytometry was used to detect phenotype, cell cycle distribution, and apoptosis of the cultured cells. Colony-forming cell (CFC) assays can evaluate multi-lineage differentiation potential of HSCs. Real-time polymerase chain reaction was employed to detect the expression of genes related to self-renewal programs and antioxidant activity. DCFH-DA probes were used to evaluate intracellular production of reactive oxygen species (ROS). Determination of the effect of different culture conditions on the balance of cytokine by cytometric bead array.

Results

Here, we show a combination, Nicotinamide (NAM) combined with pyrimidoindole derivative UM171, can massively expand LT-HSCs ex vivo, and the expanded cells maintained the capability of self-renewal and multilineage differentiation. Additionally, our data indicated that UM171 promoted self-renewal of HSCs by inducing HSCs entry into the cell cycle and activating Notch and Wnt pathways, but the infinite occurrence of this process may lead to mitochondrial metabolism disorder and differentiation of HSCs. NAM kept HSCs in their primitive and dormant states by reducing intracellular ROS levels and upregulating the expression of stemness related genes, so we believed that NAM can act as a brake to control the above process.

Conclusions

The discovery of the synergistic effect of NAM and UM171 for expanding LT-HSCs provides a new strategy in solving the clinical issue of limited numbers of HSCs.

Umbilical cord blood derived cell expansion: a potential neuroprotective therapy

Umbilical cord blood (UCB) is a rich source of beneficial stem and progenitor cells with known angiogenic, neuroregenerative and immune-modulatory properties. Preclinical studies have highlighted the benefit of UCB for a broad range of conditions including haematological conditions, metabolic disorders and neurological conditions, however clinical translation of UCB therapies is lacking. One barrier for clinical translation is inadequate cell numbers in some samples meaning that often a therapeutic dose cannot be achieved. This is particularly important when treating adults or when administering repeat doses of cells. To overcome this, UCB cell expansion is being explored to increase cell numbers. The current focus of UCB cell expansion is CD34+ haematopoietic stem cells (HSCs) for which the main application is treatment of haematological conditions. Currently there are 36 registered clinical trials that are examining the efficacy of expanded UCB cells with 31 of these being for haematological malignancies. Early data from these trials suggest that expanded UCB cells are a safe and feasible treatment option and show greater engraftment potential than unexpanded UCB. Outside of the haematology research space, expanded UCB has been trialled as a therapy in only two preclinical studies, one for spinal cord injury and one for hind limb ischemia. Proteomic analysis of expanded UCB cells in these studies showed that the cells were neuroprotective, anti-inflammatory and angiogenic. These findings are also supported by in vitro studies where expanded UCB CD34+ cells showed increased gene expression of neurotrophic and angiogenic factors compared to unexpanded CD34+ cells. Preclinical evidence demonstrates that unexpanded CD34+ cells are a promising therapy for neurological conditions where they have been shown to improve multiple indices of injury in rodent models of stroke, Parkinson's disease and neonatal hypoxic ischemic brain injury. This review will highlight the current application of expanded UCB derived HSCs in transplant medicine, and also explore the potential use of expanded HSCs as a therapy for neurological conditions. It is proposed that expanded UCB derived CD34+ cells are an appropriate cellular therapy for a range of neurological conditions in children and adults.

Metabolism and HSC fate: what NADPH is made for

Mitochondrial metabolism plays a central role in the regulation of hematopoietic stem cell (HSC) biology. Mitochondrial fatty acid oxidation (FAO) is pivotal in controlling HSC self-renewal and differentiation. Herein, we discuss recent evidence suggesting that NADPH generated in the mitochondria can influence the fate of HSCs. Although NADPH has multiple functions, HSCs show high levels of NADPH that are preferentially used for cholesterol biosynthesis. Endogenous cholesterol supports the biogenesis of extracellular vesicles (EVs), which are essential for maintaining HSC properties. We also highlight the significance of EVs in hematopoiesis through autocrine signaling. Elucidating the mitochondrial NADPH-cholesterol axis as part of the metabolic requirements of healthy HSCs will facilitate the development of new therapies for hematological disorders.

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.

Building bones for blood and beyond: the growing field of bone marrow niche model development

The bone marrow (BM) niche is a complex microenvironment that provides the signals required for regulation of hematopoietic stem cells (HSCs) and the process of hematopoiesis they are responsible for. Bioengineered models of the BM niche incorporate various elements of the in vivo BM microenvironment, including cellular components, soluble factors, a three-dimensional environment, mechanical stimulation of included cells, and perfusion. Recent advances in the bioengineering field have resulted in a spate of new models that shed light on BM function and are approaching precise imitation of the BM niche. These models promise to improve our understanding of the in vivo microenvironment in health and disease. They also aim to serve as platforms for HSC manipulation or as preclinical models for screening novel therapies for BM-associated disorders and diseases.

Advances in ex vivo expansion of hematopoietic stem and progenitor cells for clinical applications

As caretakers of the hematopoietic system, hematopoietic stem cells assure a lifelong supply of differentiated populations that are responsible for critical bodily functions, including oxygen transport, immunological protection and coagulation. Due to the far-reaching influence of the hematopoietic system, hematological disorders typically have a significant impact on the lives of individuals, even becoming fatal. Hematopoietic cell transplantation was the first effective therapeutic avenue to treat such hematological diseases. Since then, key use and manipulation of hematopoietic stem cells for treatments has been aspired to fully take advantage of such an important cell population. Limited knowledge on hematopoietic stem cell behavior has motivated in-depth research into their biology. Efforts were able to uncover their native environment and characteristics during development and adult stages. Several signaling pathways at a cellular level have been mapped, providing insight into their machinery. Important dynamics of hematopoietic stem cell maintenance were begun to be understood with improved comprehension of their metabolism and progressive aging. These advances have provided a solid platform for the development of innovative strategies for the manipulation of hematopoietic stem cells. Specifically, expansion of the hematopoietic stem cell pool has triggered immense interest, gaining momentum. A wide range of approaches have sprouted, leading to a variety of expansion systems, from simpler small molecule-based strategies to complex biomimetic scaffolds. The recent approval of Omisirge, the first expanded hematopoietic stem and progenitor cell product, whose expansion platform is one of the earliest, is predictive of further successes that might arise soon. In order to guarantee the quality of these ex vivo manipulated cells, robust assays that measure cell function or potency need to be developed. Whether targeting hematopoietic engraftment, immunological differentiation potential or malignancy clearance, hematopoietic stem cells and their derivatives need efficient scaling of their therapeutic potency. In this review, we comprehensively view hematopoietic stem cells as therapeutic assets, going from fundamental to translational.

SIRT1 activation ameliorates rhesus monkey liver fibrosis by inhibiting the TGF-β/smad signaling pathway

TGF-β/Smad signaling pathway plays an important role in the pathogenesis and progression of liver fibrosis. Silent information regulator 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD+) dependent enzyme and responsible for deacetylating the proteins. Increasing numbers of reports have shown that the molecular mechanism of SIRT1 as an effective therapeutic target for liver fibrosis but the transformation is not very clear. In the present study, liver fibrotic tissues were screened by staining with Masson, hematoxylin-eosin staining (H&E) and Immunohistochemistry (IHC) for histopathological observation from the liver biopsy of seventy-seven rhesus monkey, which fixed with 4% paraformaldehyde (PFA) after treatment with high-fat diet (HFD) for two years. And the liver function was further determined by serum biochemical tests. The mRNA levels and protein expression of rat hepatic stellate (HSC-T6) cells were determined after treatment with Resveratrol (RSV) and Nicotinamide (NAM), respectively. The results showed that with the increasing of hepatic fibrosis in rhesus monkeys, the liver function impaired, and the transforming growth factor-β1 (TGF-β1), p-Smad3 (p-Smad3) and alpha-smooth muscle actin (α-SMA) was up-regulated, while SIRT1 and Smad7 were down-regulated. Moreover, when stimulated the HSC-T6 with RSV to activate SIRT1 for 6, 12, and 24 h, the results showed that RSV promoted the expression of smad7, while the expression of TGF-β1, p-Smad3 and α-SMA were inhibited. In contrast, when the cells stimulated with NAM to inhibit SIRT1 for 6, 12, and 24 h, the Smad7 expression was decreased, while TGF-β1, p-Smad3, and α-SMA expressions were increased. These results indicate that SIRT1 acts as an important protective factor for liver fibrosis, which may be attributed to inhibiting the signaling pathway of TGF-β/Smad in hepatic fibrosis of the rhesus monkey.

Advances in hematopoietic stem cells ex vivo expansion associated with bone marrow niche

Hematopoietic stem cells (HSCs) are an ideal source for the treatment of many hematological diseases and malignancies, as well as diseases of other systems, because of their two important features, self-renewal and multipotential differentiation, which have the ability to rebuild the blood system and immune system of the body. However, so far, the insufficient number of available HSCs, whether from bone marrow (BM), mobilized peripheral blood or umbilical cord blood, is still the main restricting factor for the clinical application. Therefore, strategies to expand HSCs numbers and maintain HSCs functions through ex vivo culture are urgently required. In this review, we outline the basic biology characteristics of HSCs, and focus on the regulatory factors in BM niche affecting the functions of HSCs. Then, we introduce several representative strategies used for HSCs from these three sources ex vivo expansion associated with BM niche. These findings have deepened our understanding of the mechanisms by which HSCs balance self-renewal and differentiation and provided a theoretical basis for the efficient clinical HSCs expansion.

Projected Impact of Omidubicel-onlv on Racial/Ethnic Disparities in Allogeneic Hematopoietic Cell Transplantation (Allo-HCT) Outcomes in Hematologic Malignancies

INTRODUCTION

In a phase III clinical trial (NCT02730299), omidubicel-onlv, a nicotinamide-modified allogeneic hematopoietic progenitor cell therapy, showed rapid hematopoietic and immune recovery compared with standard umbilical cord blood (UCB) transplant across all racial/ethnic groups.

METHODS

A decision-tree model was used to project the effect of omidubicel-onlv availability on addressing health disparities in allogeneic hematopoietic cell transplantation (allo-HCT) access and outcomes for patients with hematologic malignancies. The model used a hypothetical population of 10,000 allo-HCT-eligible US adults, for whom matched related donors were not available. Patients received matched or mismatched unrelated donor, haploidentical, UCB transplant, or no transplant. Scenarios with omidubicel-onlv use of 0% (status quo), 10%, 15%, 20%, and 30% were modeled on the basis of proportional reductions in other allo-HCT sources or no transplant by racial/ethnic group.

RESULTS

Increased omidubicel-onlv use was associated with a higher proportion of patients undergoing allo-HCT, decreased time to allo-HCT, decreased 1-year non-relapse mortality, and increased 1-year overall survival, particularly among racial minorities. In the scenario modeling 20% omidubicel-onlv use, the proportion of Black patients receiving allo-HCT increased by 129%; increases were also observed in Asian (64%), Hispanic (45%), and other (42%) patient groups. Modeled time to allo-HCT improved among transplanted patients (23%) from 11.4 weeks to 8.8 weeks. One-year OS in the overall population increased by 3%, with improvements ranging from 3% for White patients to 5% for Black patients.

CONCLUSION

This study demonstrates that broad access to omidubicel-onlv could increase access to allo-HCT and improve outcomes for patients, with the greatest benefits seen among racial/ethnic minority groups.

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

BACKGROUND

High 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.

METHODS

A 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.

RESULTS

In 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).

CONCLUSION

Our 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.

Ex vivo expansion of human hematopoietic stem cells and clinical applications

Hematopoietic stem cells (HSCs) are a rare population of cells found in the bone marrow that play a critical role in lifelong hematopoiesis and the reconstitution of the hematopoietic system after hematopoietic stem cell transplantation. Hematopoietic stem cell transplantation remains the only curative treatment for patients with refractory hematologic disorders, and umbilical cord blood (CB) serves as an alternative stem cell source due to its several advantageous characteristics, including human leukocyte antigen flexibility and reduced donor burden. However, CB also has the disadvantage of containing a small number of cells, resulting in limited donor selection and a longer time for engraftment. Therefore, the development of techniques to expand HSCs ex vivo, particularly umbilical CB, is a goal in hematology. While various combinations of cytokines were once the mainstream approach, these protocols had limited expansion rates and did not lead to clinical application. However, in recent years, the development of a technique in which small molecules are added to cytokines has enabled the stable, long-term ex vivo expansion of human HSCs. Clinical trials of expanded umbilical CB using these techniques have been undertaken and have confirmed their efficacy and safety. In addition, we have successfully developed a recombinant-cytokine-free and albumin-free culture system for the long-term expansion of human HSCs. This approach could offer the potential for more selective expansion of human HSCs compared to previous protocols. This review discusses ex vivo culture protocols for expanding human HSCs and presents the results of clinical trials using these techniques, along with future perspectives.

Effects of different concentrations of nicotinamide on hematopoietic stem cells cultured in vitro

BACKGROUND

In vitro expansion to increase numbers of hematopoietic stem cells (HSCs) in cord blood could improve clinical efficacy of this vital resource. Nicotinamide (NAM) can promote HSC expansion ex vivo, but its effect on hematopoietic stem and progenitor cells (HSPCs, CD34+CD38) and functional subtypes of HSCs - short-term repopulating HSCs (ST-HSCs, CD34+CD38CD45RACD49f+) and long-term repopulating HSCs (LT-HSCs, CD34+CD38CD45RACD49f+CD90+) is not yet known. As a sirtuin 1 (SIRT1) inhibitor, NAM participates in regulating cell adhesion, polarity, migration, proliferation, and differentiation. However, SIRT1 exhibits dual effects by promoting or inhibiting differentiation in different tissues or cells. We propose that the concentration of NAM may influence proliferation, differentiation, and SIRT1 signaling of HSCs.

AIM

To evaluate the effects and underlying mechanisms of action of different concentrations of NAM on HSC proliferation and differentiation.

METHODS

CD34+ cells were purified from umbilical cord blood using MacsCD34 beads, and cultured for 10-12 d in a serum-free medium supplemented with cytokines, with different concentrations of NAM added according to experimental requirements. Flow cytometry was used to detect phenotype, cell cycle distribution, and apoptosis of the cultured cells. Real-time polymerase chain reaction was used to detect the transcription levels of target genes encoding stemness-related factors, chemokines, components of hypoxia pathways, and antioxidant enzymes. Dichloro-dihydro-fluorescein diacetate probes were used to evaluate intracellular production of reactive oxygen species (ROS). Determination of the effect of different culture conditions on the balance of cytokine by cytometric bead array.

RESULTS

Compared with the control group, the proportion and expansion folds of HSPCs (CD34+CD38) incubated with 5 mmol/L or 10 mmol/L NAM were significantly increased (all P < 0.05). The ST-HSCs ratio and fold expansion of the 5 mmol/L NAM group were significantly higher than those of the control and 10 mmol/L NAM groups (all P < 0.001), whereas the LT-HSCs ratio and fold expansion of the 10 mmol/L NAM group were significantly higher than those of the other two groups (all P < 0.05). When the NAM concentration was > 10 mmol/L, cell viability significantly decreased. In addition, compared with the 5 mmol/L NAM group, the proportion of apoptotic cells in the 10 mmol/L NAM group increased and the proportion of cells in S and G2 phase decreased. Compared with the 5 mmol/L NAM group, the HSCs incubated with 10 mmol/L NAM exhibited significantly inhibited SIRT1 expression, increased intracellular ROS content, and downregulated expression of genes encoding antioxidant enzymes (superoxide dismutase 1, peroxiredoxin 1).

CONCLUSION

Low concentrations (5 mmol/L) of NAM can better regulate the balance between proliferation and differentiation, thereby promoting expansion of HSCs. These findings allow adjustment of NAM concentrations according to expansion needs.

Ex vivo hematopoietic stem cell expansion technologies: recent progress, applications, and open questions

Hematopoietic stem cells (HSCs) are a rare but potent cell type that support life-long hematopoiesis and stably regenerate the entire blood and immune system following transplantation. HSC transplantation represents a mainstay treatment for various diseases of the blood and immune systems. The ex vivo expansion and manipulation of HSCs therefore represents an important approach to ask biological questions in experimental hematology and to help improve clinical HSC transplantation therapies. However, it has remained challenging to expand transplantable HSCs ex vivo. This review summarizes recent progress in ex vivo HSC expansion technologies and their applications to biological and clinical problems and discusses current questions in the field.

AA2P-mediated DNA demethylation synergizes with stem cell agonists to promote expansion of hematopoietic stem cells

Small molecules have enabled expansion of hematopoietic stem and progenitor cells (HSPCs), but limited knowledge is available on whether these agonists can act synergistically. In this work, we identify a stem cell agonist in AA2P and optimize a series of stem cell agonist cocktails (SCACs) to help promote robust expansion of human HSPCs. We find that SCACs provide strong growth-promoting activities while promoting retention and function of immature HSPC. We show that AA2P-mediated HSPC expansion is driven through DNA demethylation leading to enhanced expression of AXL and GAS6. Further, we demonstrate that GAS6 enhances the serial engraftment activity of HSPCs and show that the GAS6/AXL pathway is critical for robust HSPC expansion.

Expansion strategies for umbilical cord blood haematopoietic stem cells in vitro

Haematopoietic stem cell transplantation (HSCT) is considered an effective treatment for some haematopoietic malignancies, haematopoietic failure and immunodeficiency. Compared with bone marrow and mobilized peripheral blood, cord blood has the advantages of easy access, being harmless to donors and low requirement for HLA matching. In addition, umbilical cord blood transplantation (UCBT) has achieved remarkable clinical success in the past 30 years due to the low recurrence rate of malignancies treated by UCBT, mild degree of chronic graft-versus-host disease (GVHD) and good quality of life for patients after transplantation. However, the number of cells in a single cord blood is too small for rapid bone marrow implantation. We summarize the various factors involved that need to be considered in the expansion of haematopoietic stem cells (HSCs) in vitro, which all avoid complex operations, such as vector construction and virus transfection. We also found it necessary to identify a new molecule as the carrier of HSCs cultured in vitro, which not only would provide a three-dimensional structure conducive to the self-renewal of HSCs but also prevent their differentiation.

A new beginning: can omidubicel emerge as the next, viable alternative donor source?

Umbilical cord blood (UCB) transplantation (CBT) has been an important alternative donor option for patients lacking matched related donor (MRD) or unrelated donor (URD) grafts. Only 30% of patients with high-risk hematologic malignancies have a human leukocyte antigen (HLA)-identical sibling; subjects without a MRD option are referred for HLA-matched URD selection, or utilize alternative donor sources such as HLA-mismatched URD, UCB, or haploidentical donor grafts. While CBT demonstrates an excellent graft-versus-leukemia (GVL) effect, use of UCB as a graft source is limited due to a lower cell dose that can result in delayed engraftment and an immature immune system with increased infectious risk as a consequence. Together, increased transplant related mortality (TRM) has been associated with UCB allografts. Omidubicel is an ex vivo expanded single cord blood product that has demonstrated rapid engraftment, improved immune reconstitution, and reduced infectious complications in clinical trials. Omidubicel has now been granted U.S. Food & Drug Administration approval to enhance neutrophil recovery and decrease infectious risk. This review will focus on CBT, benefits and barriers to using this alternative donor source, and finally the potential advancements with incorporation of omidubicel in the transplant setting for malignant and non-malignant diseases.

Nicotinamide enhances natural killer cell function and yields remissions in patients with non-Hodgkin lymphoma

Allogeneic natural killer (NK) cell adoptive transfer has shown the potential to induce remissions in relapsed or refractory leukemias and lymphomas, but strategies to enhance NK cell survival and function are needed to improve clinical efficacy. Here, we demonstrated that NK cells cultured ex vivo with interleukin-15 (IL-15) and nicotinamide (NAM) exhibited stable induction of l-selectin (CD62L), a lymphocyte adhesion molecule important for lymph node homing. High frequencies of CD62L were associated with elevated transcription factor forkhead box O1 (FOXO1), and NAM promoted the stability of FOXO1 by preventing proteasomal degradation. NK cells cultured with NAM exhibited metabolic changes associated with elevated glucose flux and protection against oxidative stress. NK cells incubated with NAM also displayed enhanced cytotoxicity and inflammatory cytokine production and preferentially persisted in xenogeneic adoptive transfer experiments. We also conducted a first-in-human phase 1 clinical trial testing adoptive transfer of NK cells expanded ex vivo with IL-15 and NAM (GDA-201) combined with monoclonal antibodies in patients with relapsed or refractory non-Hodgkin lymphoma (NHL) and multiple myeloma (MM) (NCT03019666). Cellular therapy with GDA-201 and rituximab was well tolerated and yielded an overall response rate of 74% in 19 patients with advanced NHL. Thirteen patients had a complete response, and 1 patient had a partial response. GDA-201 cells were detected for up to 14 days in blood, bone marrow, and tumor tissues and maintained a favorable metabolic profile. The safety and efficacy of GDA-201 in this study support further development as a cancer therapy.

Rev1 deficiency induces a metabolic shift in MEFs that can be manipulated by the NAD+ precursor nicotinamide riboside

Replication stress, caused by Rev1 deficiency, is associated with mitochondrial dysfunction, and metabolic stress. However, the overall metabolic alterations and possible interventions to rescue the deficits due to Rev1 loss remain unclear. Here, we report that loss of Rev1 leads to intense changes in metabolites and that this can be manipulated by NAD ⁺ supplementation. Autophagy decreases in Rev1^-/- mouse embryonic fibroblasts (MEFs) and can be restored by supplementing the NAD⁺ precursor nicotinamide riboside (NR). The abnormal mitochondrial morphology in Rev1^-/- MEFs can be partially reversed by NR supplementation, which also protects the mitochondrial cristae from rotenone-induced degeneration. In nematodes rev-1 deficiency causes sensitivity to oxidative stress but this cannot be rescued by NR supplementation. In conclusion, Rev1 deficiency leads to metabolic dysregulation of especially lipid and nucleotide metabolism, impaired autophagy, and mitochondrial anomalies, and all of these phenotypes can be improved by NR replenishment in MEFs.

Reconstruction of bone marrow microenvironment for expansion of hematopoietic stem cells by a histone deacetylase inhibitor

Ex vivo expansion of hematopoietic stem cells (HSCs) is an approach for overcoming cell insufficiency for umbilical cord blood transplantation. It was suggested that in common ex vivo cultures, the stemness specificity of HSCs is rapidly reducing due to DNA hypermethylation. Here, Nicotinamide (NAM), a DNA methyltransferase and histone deacetylase inhibitor, is used with a bioengineered Bone Marrow-like niche (BLN) for HSC ex vivo expansion. The CFSE cell proliferation assay was used for tracking HSCs division. qRT-PCR was conducted to assay the HOXB4 mRNA expression levels. The morphology of BLN-cultured cells was analyzed using scanning electron microscopy (SEM). NAM boosted the induction of HSC proliferation in the BLN group compared to the control group. In addition, the ability of HSCs to colonize was more significant in the BLN group than in the control group. Our data suggest that the presence of NAM in bioengineered niches promotes HSC proliferation. The presented approach showed that small molecules could be used in the clinical setting to overcome the limited number of CD34+ cells in cord blood units.

Umbilical cord blood derived cellular therapy: advances in clinical development

While cord blood (CB) is primarily utilized in allogeneic hematopoietic cell transplantation (HCT), the development of novel cell therapy products from CB is a growing and developing field. Compared to adult blood, CB is characterized by a higher percentage of hematopoietic stem cells (HSCs) and progenitor cells, less mature immune cells that retain a high capacity of proliferation, and stronger immune tolerance that requires less stringent HLA-matching when used in the allogenic setting. Given that CB is an FDA regulated product and along with its unique cellular composition, CB lends itself as a readily available and safe starting material for the development of off-the-shelf cell therapies. Moreover, non-hematologic cells such as mesenchymal stem cell (MSCs) residing in CB or CB tissue also have potential in regenerative medicine and inflammatory and autoimmune conditions. In this review, we will focus on recent clinical development on CB-derived cellular therapies in the field of oncology, including T-cell therapies such as chimeric antigen receptor (CAR) T-cells, regulatory T-cells, and virus-specific T-cells; NK-cell therapies, such as NK cell engagers and CAR NK-cells; CB-HCT and various modifications; as well as applications of MSCs in HCT.

Multicenter Long-Term Follow-Up of Allogeneic Hematopoietic Cell Transplantation with Omidubicel: A Pooled Analysis of Five Prospective Clinical Trials

Omidubicel is an umbilical cord blood (UCB)-derived ex vivo-expanded cellular therapy product that has demonstrated faster engraftment and fewer infections compared with unmanipulated UCB in allogeneic hematopoietic cell transplantation. Although the early benefits of omidubicel have been established, long-term outcomes remain unknown. We report on a planned pooled analysis of 5 multicenter clinical trials including 105 patients with hematologic malignancies or sickle cell hemoglobinopathy who underwent omidubicel transplantation at 26 academic transplantation centers worldwide. With a median follow-up of 22 months (range, .3 to 122 months), the 3-year estimated overall survival and disease-free survival were 62.5% and 54.0%, respectively. With up to 10 years of follow-up, omidubicel showed durable trilineage hematopoiesis. Serial quantitative assessments of CD3+, CD4+, CD8+, CD19+, CD116+CD56+, and CD123+ immune subsets revealed median counts remaining within normal ranges through up to 8 years of follow-up. Secondary graft failure occurred in 5 patients (5%) in the first year, with no late cases reported. One case of donor-derived myeloid neoplasm was reported at 40 months post-transplantation. This was also observed in a control arm patient who received only unmanipulated UCB. Overall, omidubicel demonstrated stable trilineage hematopoiesis, immune competence, and graft durability in extended follow-up.

Immune Reconstitution Profiling Suggests Antiviral Protection After Transplantation with Omidubicel: a Phase 3 Substudy

BACKGROUND

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative treatment for hematological malignancies and non-malignant disorders. Rapid immune reconstitution (IR) following allogeneic HCT has been shown to be associated with improved clinical outcomes and lower infection rates. A global phase 3 trial (NCT02730299) of omidubicel, an advanced cell therapy manufactured from an appropriately human leukocyte antigen-matched single umbilical cord blood (UCB) unit, showed faster hematopoietic recovery, reduced rates of infection, and shorter hospitalizations in patients randomized to omidubicel compared with those randomized to standard UCB.

OBJECTIVE

This optional, prospective substudy of the phase 3 trial characterized the IR kinetics following HCT with omidubicel compared with UCB in a systematic and detailed manner.

STUDY DESIGN

In this substudy, 37 patients from 14 global sites were included (omidubicel: n=17, UCB: n=20). Peripheral blood samples were collected over 10 predefined time points from 7 to 365 days post-HCT. Flow cytometry immunophenotyping, T cell receptor excision circle quantification, and T cell receptor sequencing were employed to evaluate the longitudinal IR kinetics post-transplant and their association with clinical outcomes.

RESULTS

Patient characteristics in the two comparator cohorts were overall statistically similar, except for age and total body irradiation (TBI) based conditioning regimens. The median age (range) for patients who received omidubicel or UCB was 30 (13-62) years and 43 (19-55) years, respectively. The percentages of patients receiving TBI based conditioning regimens were 47% and 70% for omidubicel and UCB recipients, respectively. Graft characteristics differed in their cellular composition. Omidubicel recipients received a 33-fold higher median dose of CD34+ stem cells, while receiving one third of the median CD3+ lymphocyte dose infused to UCB transplanted patients. Compared with UCB, omidubicel recipients exhibited faster IR of all measured lymphoid and myelomonocytic subpopulations, predominantly in the first 14 days post-transplant. This effect involved circulating natural killer (NK) cells, helper T cells, monocytes, and dendritic cells, with superior long-term B cell recovery from Day 28. One-week post-HCT, omidubicel recipients exhibited 4.1 and 7.7 -fold increases in the median helper T and NK cell counts respectively, compared to their UCB transplanted counterparts. By three weeks post-HCT, omidubicel transplanted patients were 3-fold more likely to achieve clinically relevant helper T and NK cell counts of 100 cells/ µL or above. Similar to UCB, omidubicel yielded a balanced cellular subpopulation composition and diverse T cell receptor repertoire in the short to long term. Omidubicel's CD34+ cell content correlated with faster IR by Day 7 post-HCT, which in turn coincided with earlier hematopoietic recovery. Lastly, early NK and helper T cell reconstitution correlated with a decreased rate of post-HCT viral infections, suggesting a plausible explanation for this phenomenon among omidubicel recipients in the phase 3 study.

CONCLUSIONS

Our findings suggest that omidubicel efficiently promotes IR across multiple immune cells, including CD4+ T cells, B cells, NK cells, and dendritic cell subtypes as early as 7 days post-transplant, potentially endowing recipients of omidubicel with early protective immunity.

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.

In Vitro Human Haematopoietic Stem Cell Expansion and Differentiation

The haematopoietic system plays an essential role in our health and survival. It is comprised of a range of mature blood and immune cell types, including oxygen-carrying erythrocytes, platelet-producing megakaryocytes and infection-fighting myeloid and lymphoid cells. Self-renewing multipotent haematopoietic stem cells (HSCs) and a range of intermediate haematopoietic progenitor cell types differentiate into these mature cell types to continuously support haematopoietic system homeostasis throughout life. This process of haematopoiesis is tightly regulated in vivo and primarily takes place in the bone marrow. Over the years, a range of in vitro culture systems have been developed, either to expand haematopoietic stem and progenitor cells or to differentiate them into the various haematopoietic lineages, based on the use of recombinant cytokines, co-culture systems and/or small molecules. These approaches provide important tractable models to study human haematopoiesis in vitro. Additionally, haematopoietic cell culture systems are being developed and clinical tested as a source of cell products for transplantation and transfusion medicine. This review discusses the in vitro culture protocols for human HSC expansion and differentiation, and summarises the key factors involved in these biological processes.

Ex vivo reprogramming of human hematopoietic stem cells is accompanied by increased transcripts of genes regulating metabolic integrity

The regenerative potential of human hematopoietic stem cells (HSCs) is functionally defined by their ability to provide life-long blood cell production and to repopulate myeloablated allogeneic transplant recipients. The expansion of HSC numbers is dependent not only on HSC divisions but also on a coordinated adaptation of HSCs to metabolic stress. These variables are especially critical during the ex vivo culture of HSCs with cytokine combinations, which frequently results in HSC exhaustion. We have previously reported that human CD34⁺ hematopoietic stem and progenitor cells (HSPCs) can be efficiently reprogrammed ex vivo and that the number of phenotypic HSCs with long-term repopulation capacity is expanded in the presence of a combination of cytokines and an epigenetic modifier. Here, we present evidence that ex vivo HSC reprogramming and maintenance is accompanied by increased transcripts of genes regulating metabolic integrity, including SIRT1 and SIRT3.

Therapeutic targeting and HSC proliferation by small molecules and biologicals

Hematopoietic stem cells (HSCs) have considerably therapeutic value on autologous and allogeneic transplantation for many malignant/non-malignant hematological diseases, especially with improvement of gene therapy. However, acquirement of limited cell dose from HSC sources is the main handicap for successful transplantation. Therefore, many strategies based on the utilization of various cytokines, interaction of stromal cells, modulation of several extrinsic and intrinsic factors have been developed to promote ex vivo functional HSC expansion with high reconstitution ability until today. Besides all these strategies, small molecules become prominent with their ease of use and various advantages when they are translated to the clinic. In the last two decades, several small molecule compounds have been investigated in pre-clinical studies and, some of them were evaluated in different stages of clinical trials for their safety and efficiencies. In this chapter, we will present an overview of HSC biology, function, regulation and also, pharmacological HSC modulation with small molecules from pre-clinical and clinical perspectives.

Ex Vivo Expansion and Homing of Human Cord Blood Hematopoietic Stem Cells

Cord blood (CB) has been proven to be an alternative source of haematopoietic stem cells (HSCs) for clinical transplantation and has multiple advantages, including but not limited to greater HLA compatibility, lower incidence of graft-versus-host disease (GvHD), higher survival rates and lower relapse rates among patients with minimal residual disease. However, the limited number of HSCs in a single CB unit limits the wider use of CB in clinical treatment. Many efforts have been made to enhance the efficacy of CB HSC transplantation, particularly by ex vivo expansion or enhancing the homing efficiency of HSCs. In this chapter, we will document the major advances regarding human HSC ex vivo expansion and homing and will also discuss the possibility of clinical translation of such laboratory work.

Shedding light on structure, function and regulation of human sirtuins: a comprehensive review

Sirtuins play an important role in signalling pathways associated with various metabolic regulations. They possess mono-ADP-ribosyltransferase or deacylase activity like demalonylase, deacetylase, depalmitoylase, demyristoylase and desuccinylase activity. Sirtuins are histone deacetylases which depends upon nicotinamide adenine dinucleotide (NAD) that deacetylate lysine residues. There are a total of seven human sirtuins that have been identified namely, SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6 and SIRT7. The subcellular location of mammalian sirtuins, SIRT1, SIRT6, and SIRT7 are in the nucleus; SIRT3, SIRT4, and SIRT5 are in mitochondria, and SIRT2 is in cytoplasm. Structurally sirtuins contains a N-terminal, a C-terminal and a Zn+ binding domain. The sirtuin family has been found to be crucial for maintaining lipid and glucose homeostasis, and also for regulating insulin secretion and sensitivity, DNA repair pathways, neurogenesis, inflammation, and ageing. Based on the literature, sirtuins are overexpressed and play an important role in tumorigenicity in various types of cancer such as non-small cell lung cancer, colorectal cancer, etc. In this review, we have discussed about the different types of human sirtuins along with their structural and functional features. We have also discussed about the various natural and synthetic regulators of sirtuin activities like resveratrol. Our overall study shows that the correct regulation of sirtuins can be a good target for preventing and treating various diseases for improving the human lifespan. To investigate the true therapeutic potential of sirtuin proteins and their efficacy in a variety of pathological diseases, a better knowledge of the link between the structure and function of sirtuin proteins would be necessary.

Health-Related Quality of Life Following Allogeneic Hematopoietic Cell Transplantation with Omidubicel versus Umbilical Cord Blood

Omidubicel is an advanced cell therapy derived from umbilical cord blood (UCB) for use in allogeneic hematopoietic cell transplantation (HCT). A recent randomized phase 3 clinical trial demonstrated faster engraftment, shorter length of hospital stays, and lower rates of infection with omidubicel compared with standard UCB transplantation in patients with high-risk hematologic malignancies. Despite the proven clinical benefits of omidubicel, its impact on health-related quality of life (HRQL) from the patient's perspective has not been described. This study analyzed patient-reported HRQL measures collected prospectively in the randomized phase 3 trial comparing omidubicel to standard UCB transplantation. A total of 108 patients at 33 international stem cell transplantation centers underwent myeloablative allogeneic HCT with either omidubicel or standard UCB. Patients completed serial HRQL questionnaires at screening and on days 42, 100, 180, and 365 post-transplantation. The HRQL surveys included the Functional Assessment of Cancer Therapy-Bone Marrow Transplant (FACT-BMT), a 50-item cancer-specific questionnaire assessing physical, functional, emotional, social/family, and HCT-specific well-being, and the EuroQol 5-Dimension 3-Level, a 5-item generic HRQL survey. A mixed model with repeated measures was used to compare changes in HRQL from baseline in the 2 treatment arms. The average change in HRQL scores over time was compared by estimating the difference in the area under the curve (AUC) in each treatment group. Seventy-five patients (omidubicel arm, n = 37; standard UCB arm, n = 38) who completed the FACT-BMT at baseline and on 1 or more follow-up visits were included in this study. Baseline characteristics were similar in the 2 treatment arms. Over the first year post-transplantation, the AUCs of mean changes in physical, functional, and total FACT-BMT scores indicated significantly better HRQL with omidubicel (P < .05), with mean differences across time points ranging from 1.4 to 3.1 points, 1.6 to 3.2 points, and 7.2 to 11.0 points, respectively. The minimal clinically important difference was exceeded at 1 or more time points for each of these measures. The HRQL improvements with omidubicel were observed as early as 42 days post-transplantation and persisted at 1 year, indicating the potential long-term benefits of omidubicel on HRQL. Across all patients, adverse clinical outcomes, such as grade 3 viral infections and lower rates of neutrophil engraftment, were associated with worse HRQL scores. The observed improvements in HRQL measures may reflect the known clinical benefits of omidubicel. Compared with standard UCB, allogeneic HCT with omidubicel resulted in significant and clinically meaningful improvements in patient-reported HRQL measures.

BML-260 promotes the growth of cord blood and mobilized peripheral blood hematopoietic stem and progenitor cells with improved reconstitution ability

Hematopoietic stem cells (HSCs), which are multipotent and have the ability to self-renew, are frequently used in the treatment of hematological diseases and cancer. Small molecules that target HSC quiescence regulators could be used for ex vivo expansion of both mobilized peripheral blood (mPB) and umbilical cord blood (UCB) hematopoietic stem and progenitor cells (HSPC). We identified and investigated 35 small molecules that target HSC quiescence factors. We looked at how they affected HSC activity, such as expansion, quiescence, multilineage capacity, cycling ability, metabolism, cytotoxicity, and genotoxicity. A transplantation study was carried out on immunocompromised mice to assess the expanded cells' repopulation and engraftment abilities. 4-[(5Z)-5-benzylidene-4-oxo-2-sulfanylidene-1,3-thiazolidin-3-yl]benzoic acid (BML)-260 and tosyl-l-arginine methyl ester (TAME) significantly increased both mPB and UCB-HSPC content and activated HSC re-entry into the cell cycle. The improved multilineage capacity was confirmed by the colony forming unit (CFU) assay. Furthermore, gene expression analysis revealed that BML-260 and TAME molecules aided HSC expansion by modulating cell cycle kinetics, such as p27, SKP2, and CDH1. In addition to these in vitro findings, we discovered that BML-260-expanded HSCs had a high hematopoietic reconstitution capacity with increased immune cell content after xenotransplantation into immunocompromised mice. In addition to the BML-260 molecule, a comparison study of serum-containing and serum-free chemically defined media, including various supplements, was performed. These in vitro and xenotransplantation results show that BML-260 molecules can be used for human HSC expansion and regulation of function. Furthermore, the medium composition discovered may be a novel platform for human HSPC expansion that could be used in clinical trials.

The monoculture of cord-blood-derived CD34+ cells by an automated, membrane-based dynamic perfusion system with a novel cytokine cocktail

Human leukocyte antigen (HLA)-matched cord blood (CB) transplantation is a procedure for the treatment of certain hematological malignancies, hemoglobinopathies, and autoimmune disorders. However, one of the challenges is to provide a sufficient number of T cell-depleted hematopoietic stem and progenitor cells. Currently, only 4%-5% of the CB units stored in CB banks contain enough CD34⁺ cells for engrafting 70-kg patients. To support this clinical need, we have developed an automated expansion protocol for CB-derived CD34⁺ cells in the Quantum system's dynamic perfusion bioreactor using a novel cytokine cocktail comprised of stem cell factor (SCF), thrombopoietin (TPO), fms-like tyrosine kinase 3 ligand (Flt-3L), interleukin-3 (IL-3), IL-6, glial cell line-derived neurotrophic factor (GDNF), StemRegenin 1 (SR-1), and a fibronectin-stromal-cell-derived factor-1 (SDF-1)-coated membrane. In an 8-day expansion of a 2 × 10⁶ positively selected CD34⁺ cell inoculum from 3 donor lineages, the mean cell harvest and cell viability were 1.02 × 10⁸ cells and 95.5%, respectively, and the mean frequency of the CD45⁺CD34⁺ immunophenotype was 54.3%. The mean differentiated cell frequencies were 0.5% for lymphocytes, 15.8% for neutrophils, and 15.4% for platelets. These results demonstrate that the automated monoculture protocol can support the expansion of CD34⁺ cells with minimal lymphocyte residual.

Autophagy-inducing nutritional interventions in experimental and clinical oncology

Numerous pro-autophagic dietary interventions are being investigated for their potential cancer-preventive or therapeutic effects. This applies to different fasting regimens, methionine restriction and ketogenic diets. In addition, the supplementation of specific micronutrients such as nicotinamide (vitamin B3) or spermidine induces autophagy. In humans, leanness, plant-based diets (that may lead to partial methionine restriction) and high dietary uptake of spermidine are associated with a low incidence of cancers. Moreover, clinical trials have demonstrated the capacity of nicotinamide to prevent non-melanoma skin carcinogenesis. Multiple interventional trials are evaluating the capacity of autophagy-inducing regimens to improve the outcome of chemotherapy and immunotherapy. Here, we discuss the mechanistic underpinnings of autophagy induction by nutritional interventions, as well as the mechanisms through which autophagy induction in malignant or immune cells improves anticancer immunosurveillance.

Clinical Progress and Preclinical Insights Into Umbilical Cord Blood Transplantation Improvement

The application of umbilical cord blood (UCB) as an important source of hematopoietic stem and progenitor cells (HSPCs) for hematopoietic reconstitution in the clinical context has steadily grown worldwide in the past 30 years. UCB has advantages that include rapid availability of donors, less strict HLA-matching demands, and low rates of graft-versus-host disease (GVHD) versus bone marrow (BM) and mobilized peripheral blood (PB). However, the limited number of HSPCs within a single UCB unit often leads to delayed hematopoietic engraftment, increased risk of transplant-related infection and mortality, and proneness to graft failure, thus hindering wide clinical application. Many strategies have been developed to improve UCB engraftment, most of which are based on 2 approaches: increasing the HSPC number ex vivo before transplantation and enhancing HSPC homing to the recipient BM niche after transplantation. Recently, several methods have shown promising progress in UCB engraftment improvement. Here, we review the current situations of UCB manipulation in preclinical and clinical settings and discuss challenges and future directions.

Update on preclinical and clinical efforts on ex-vivo expansion of hematopoietic stem and progenitor cells

PURPOSE OF REVIEW

Ex-vivo expansion of hematopoietic stem cells (HSCs) is one potential approach to enhance the clinical efficacy of hematopoietic cell transplantation-based therapy for malignant and nonmalignant blood diseases. Here, we discuss the major progress of preclinical and clinical studies on the ex-vivo expansion of human HSCs and progenitor cells (HPCs).

RECENT FINDINGS

Single-cell RNA sequencing identified ADGRG1 as a reliable marker of functional HSCs upon ex-vivo expansion-induced mitochondrial oxidative stress. Both SR1 and UM171 significantly promote ex-vivo expansion of human cord blood HSCs and HPCs, as determined in preclinical animal models. Encouraged by these findings from the bench, multiple phase I/II and phase II clinical trials have been conducted to evaluate the safety, feasibility and efficacy of SR1-expanded and UM171-expanded cord blood units in patients with hematological malignancy.

SUMMARY

Preliminary data from multiple phase I/II clinical trials regarding transplants of ex-vivo-expanded HSCs and HPCs have demonstrated that ex-vivo expansion may be used to overcome the limitation of the rarity of HSCs without compromising stemness.

SAHA Enhances Differentiation of CD34+CD45+ Hematopoietic Stem and Progenitor Cells from Pluripotent Stem Cells Concomitant with an Increase in Hemogenic Endothelium

Epigenetic modification is an important process during hematopoietic cell differentiation. Histone deacetylase (HDAC) inhibitors have previously been shown to enhance expansion of umbilical cord blood-derived hematopoietic stem cells (HSCs). However, the effect of HDAC inhibitors on pluripotent stem cells (PSCs) in this context is less understood. For years, investigators have considered PSC-derived natural killer (NK) and T-cell therapies. These "off-the-shelf" cellular therapies are now entering the clinic. However, the in vitro commitment of PSCs to the hematopoietic lineage is inefficient and represents a major bottleneck. We investigated whether HDAC inhibitors (HDACi) influence human PSC differentiation into CD34+CD45+ hematopoietic stem and progenitor cells (HSPCs), focusing on hemogenic endothelium (HE). Pluripotent stem cells cultured in the presence of HDACi showed a 2-5 times increase in HSPCs. Concurrent with this, HDACi-treated PSCs increased expression of 7 transcription factors (HOXA5, HOXA9, HOXA10, RUNX1, ERG, SPI1, and LCOR) recently shown to convert HE to HSPCs. ChIP-qPCR showed that SAHA upregulated acetylated-H3 at the promoter region of the above key genes. SAHA-treated human PSC-derived CD34+CD45+ cells showed primary engraftment in immunodeficient mice, but not serial transplantation. We further demonstrate that SAHA-derived HSPCs could differentiate into functional NK cells in vitro. The addition of SAHA is an easy and effective approach to overcoming the bottleneck in the transition from PSC to HSPCs for "off-the-shelf" cellular immunotherapy.

NAD+ Precursors Repair Mitochondrial Function in Diabetes and Prevent Experimental Diabetic Neuropathy

Axon degeneration in diabetic peripheral neuropathy (DPN) is associated with impaired NAD+ metabolism. We tested whether the administration of NAD+ precursors, nicotinamide mononucleotide (NMN) or nicotinamide riboside (NR), prevents DPN in models of Type 1 and Type 2 diabetes. NMN was administered to streptozotocin (STZ)-induced diabetic rats and STZ-induced diabetic mice by intraperitoneal injection at 50 or 100 mg/kg on alternate days for 2 months. mice The were fed with a high fat diet (HFD) for 2 months with or without added NR at 150 or 300 mg/kg for 2 months. The administration of NMN to STZ-induced diabetic rats or mice or dietary addition of NR to HFD-fed mice improved sensory function, normalized sciatic and tail nerve conduction velocities, and prevented loss of intraepidermal nerve fibers in skin samples from the hind-paw. In adult dorsal root ganglion (DRG) neurons isolated from HFD-fed mice, there was a decrease in NAD+ levels and mitochondrial maximum reserve capacity. These impairments were normalized in isolated DRG neurons from NR-treated mice. The results indicate that the correction of NAD+ depletion in DRG may be sufficient to prevent DPN but does not significantly affect glucose tolerance, insulin levels, or insulin resistance.

Isolation, Maintenance and Expansion of Adult Hematopoietic Stem/Progenitor Cells and Leukemic Stem Cells

Simple Summary

Transplantation of adult hematopoietic stem cells is an important therapeutic tool to help patients suffering from diverse hematological disorders. All types of blood cells can develop from a single hematopoietic stem cell underlining their enormous potential. Intense efforts are ongoing to generate “engraftable” human hematopoietic stem cells to treat hematopoietic diseases and to understand the molecular machinery driving them. Leukemic stem cells represent a low frequency subpopulation of leukemia cells that possess stem cell properties. They can instigate, maintain, and serially propagate leukemia in vivo, while they retain the capacity to differentiate into committed progenitors. Leukemic stem cells are unaffected by many therapeutic strategies and represent the major cause of relapse. We here describe all methods to maintain and expand murine and human hematopoietic cells in culture and describe their specific advantages. These methods are also employed to understand the biology of leukemic stem cells and to identify novel therapeutic strategies.

Abstract

Hematopoietic stem cells (HSCs) are rare, self-renewing cells that perch on top of the hematopoietic tree. The HSCs ensure the constant supply of mature blood cells in a tightly regulated process producing peripheral blood cells. Intense efforts are ongoing to optimize HSC engraftment as therapeutic strategy to treat patients suffering from hematopoietic diseases. Preclinical research paves the way by developing methods to maintain, manipulate and expand HSCs ex vivo to understand their regulation and molecular make-up. The generation of a sufficient number of transplantable HSCs is the Holy Grail for clinical therapy. Leukemia stem cells (LSCs) are characterized by their acquired stem cell characteristics and are responsible for disease initiation, progression, and relapse. We summarize efforts, that have been undertaken to increase the number of long-term (LT)-HSCs and to prevent differentiation towards committed progenitors in ex vivo culture. We provide an overview and compare methods currently available to isolate, maintain and enrich HSC subsets, progenitors and LSCs and discuss their individual advantages and drawbacks.

Safe and efficient in vivo hematopoietic stem cell transduction in nonhuman primates using HDAd5/35++ vectors

We tested a new in vivo hematopoietic stem cell (HSC) transduction/selection approach in rhesus macaques using HSC-tropic, integrating, helper-dependent adenovirus vectors (HDAd5/35++) designed for the expression of human γ-globin in red blood cells (RBCs) to treat hemoglobinopathies. We show that HDAd5/35++ vectors preferentially transduce HSCs in vivo after intravenous injection into granulocyte colony-stimulating factor (G-CSF)/AMD3100-mobilized animals and that transduced cells return to the bone marrow and spleen. The approach was well tolerated, and the activation of proinflammatory cytokines that are usually associated with intravenous adenovirus vector injection was successfully blunted by pre-treatment with dexamethasone in combination with interleukin (IL)-1 and IL-6 receptor blockers. Using our MGMT^P140K-based in vivo selection approach, γ-globin⁺ RBCs increased in all animals with levels up to 90%. After selection, the percentage of γ-globin⁺ RBCs declined, most likely due to an immune response against human transgene products. Our biodistribution data indicate that γ-globin⁺ RBCs in the periphery were mostly derived from mobilized HSCs that homed to the spleen. Integration site analysis revealed a polyclonal pattern and no genotoxicity related to transgene integrations. This is the first proof-of-concept study in nonhuman primates to show that in vivo HSC gene therapy could be feasible in humans without the need for high-dose chemotherapy conditioning and HSC transplantation.

SIRT1-SIRT7 Expression in Patients with Lymphoproliferative Disorders Undergoing Hematopoietic Stem Cell Mobilization

Sirtuins are involved in the fate of hematopoietic stem cells (HSCs), including their metabolism, stress response, differentiation, migration, and apoptosis. The aim of this study was to explore SIRT1-7 expression during HSC mobilization. The study included 50 patients with lymphoproliferative disorders (39 multiple myeloma, 11 lymphoma). Samples were taken before mobilization (day 0) and on the day of first apheresis (day A). The sirtuin expression was evaluated by the Droplet Digital PCR (ddPCR) method. A significant increase of the SIRT1, SIRT2, SIRT3, SIRT5, SIRT6, and SIRT7 levels measured at day A as compared to baseline was observed. The study revealed a positive correlation between SIRT5, SIRT6, and SIRT7 expression and the CD34+ peak value in peripheral blood and the number of CD34+ cells collected on day A. Patients from the SIRT7 “high expressors” group collected more CD34+ cells on day A than “low expressors”. Upregulated expressions of SIRT3 and SIRT7 on the day of first apheresis were observed in patients in complete remission status (CR) as compared to the non-CR group. Our results suggest that the investigated sirtuins may influence the HSC migration and hematopoietic landscape during mobilization. SIRT5, SIRT6, and SIRT7 may be associated with the efficacy of HSC mobilization.

Development and clinical advancement of small molecules for ex vivo expansion of hematopoietic stem cell

Hematopoietic stem cell (HSC) transplantation is the only curative therapy for many diseases. HSCs from umbilical cord blood (UCB) source have many advantages over from bone marrow. However, limited HSC dose in a single CB unit restrict its widespread use. Over the past two decades, ex vivo HSC expansion with small molecules has been an effective approach for obtaining adequate HSCs. Till now, several small-molecule compounds have entered the phase I/II trials, showing safe and favorable pharmacological profiles. As HSC expansion has become a hot topic over recent years, many newly identified small molecules along with novel biological mechanisms for HSC expansion would help solve this challenging issue. Here, we will give an overview of HSC biology, discovery and medicinal chemistry development of small molecules, natural products targeting for HSC expansion, and their recent clinical progresses, as well as potential protein targets for HSC expansion.

Umbilical cord blood transplantation: Still growing and improving

Umbilical cord blood transplantation (UCBT) has been performed in the clinic for over 30 years. The biological and immunological characteristics of umbilical cord blood (UCB) have been re-recognized in recent years. UCB, previously considered medical waste, is rich in hematopoietic stem cells (HSCs), which are naïve and more energetic and more easily expanded than other stem cells. UCB has been identified as a reliable source of HSCs for allogeneic hematopoietic stem cell transplantation (allo-HSCT). UCBT has several advantages over other methods, including no harm to mothers and donors, an off-the-shelf product for urgent use, less stringent HLA match, lower incidence and severity of chronic graft-vs-host disease (GVHD), and probably a stronger graft-vs-leukemia effect, especially for minimal residual disease-positive patients before transplant. Recent studies have shown that the outcome of UCBT has been improved and is comparable to other types of allo-HSCT. Currently, UCBT is widely used in malignant, nonmalignant, hematological, congenital and metabolic diseases. The number of UCB banks and transplantation procedures increased exponentially before 2013. However, the number of UCBTs increased steadily in Asia and China but decreased in the United States and Europe year-on-year from 2013 to 2019. In this review, we focus on the development of UCBT over the past 30 years, the challenges it faces and the strategies for future improvement, including increasing UCB numbers, cord blood unit selection, conditioning regimens and GVHD prophylaxis for UCBT, and management of complications of UCBT.

Lymphoid and myeloid immune cell reconstitution after nicotinamide-expanded cord blood transplantation

Omidubicel (nicotinamide-expanded cord blood) is a potential alternative source for allogeneic hematopoietic cell transplantation (HCT) when an HLA-identical donor is lacking. A phase I/II trial with standalone omidubicel HCT showed rapid and robust neutrophil and platelet engraftment. In this study, we evaluated the immune reconstitution (IR) of patients receiving omidubicel grafts during the first 6 months post-transplant, as IR is critical for favorable outcomes of the procedure. Data was collected from the omidubicel phase I-II international, multicenter trial. The primary endpoint was the probability of achieving adequate CD4+ T-cell IR (CD4IR: > 50 × 106/L within 100 days). Secondary endpoints were the recovery of T-cells, natural killer (NK)-cells, B-cells, dendritic cells (DC), and monocytes as determined with multicolor flow cytometry. LOESS-regression curves and cumulative incidence plots were used for data description. Thirty-six omidubicel recipients (median 44; 13-63 years) were included, and IR data was available from 28 recipients. Of these patients, 90% achieved adequate CD4IR. Overall, IR was complete and consisted of T-cell, monocyte, DC, and notably fast NK- and B-cell reconstitution, compared to conventional grafts. Our data show that transplantation of adolescent and adult patients with omidubicel results in full and broad IR, which is comparable with IR after HCT with conventional graft sources.

Omidubicel vs standard myeloablative umbilical cord blood transplantation: results of a phase 3 randomized study

Omidubicel is an ex vivo expanded hematopoietic progenitor cell and nonexpanded myeloid and lymphoid cell product derived from a single umbilical cord blood unit. We report results of a phase 3 trial to evaluate the efficacy of omidubicel compared with standard umbilical cord blood transplantation (UCBT). Between January 2017 and January 2020, 125 patients age 13 to 65 years with hematologic malignancies were randomly assigned to omidubicel vs standard UCBT. Patients received myeloablative conditioning and prophylaxis with a calcineurin inhibitor and mycophenolate mofetil for graft-versus-host disease (GVHD). The primary end point was time to neutrophil engraftment. The treatment arms were well balanced and racially diverse. Median time to neutrophil engraftment was 12 days (95% confidence interval [CI], 10-14 days) for the omidubicel arm and 22 days (95% CI, 19-25 days) for the control arm (P < .001). The cumulative incidence of neutrophil engraftment was 96% for patients receiving omidubicel and 89% for patients receiving control transplants. The omidubicel arm had faster platelet recovery (55% vs 35% recovery by 42 days; P = .028), had a lower incidence of first grade 2 to 3 bacterial or invasive fungal infection (37% vs 57%; P = .027), and spent more time out of hospital during the first 100 days after transplant (median, 61 vs 48 days; P = .005) than controls. Differences in GVHD and survival between the 2 arms were not statistically significant. Transplantation with omidubicel results in faster hematopoietic recovery and reduces early transplant-related complications compared with standard UCBT. The results suggest that omidubicel may be considered as a new standard of care for adult patients eligible for UCBT. The trial was registered at www.clinicaltrials.gov as #NCT02730299.

Preferential expansion of human CD34+CD133+CD90+ hematopoietic stem cells enhances gene-modified cell frequency for gene therapy

CD34+CD133+CD90+ hematopoietic stem cells (HSCs) are responsible for long-term multi-lineage hematopoiesis and the high frequency of gene-modified HSCs is crucial for the success of hematopoietic stem and progenitor cell (HSPC) gene therapy. However, the ex vivo culture and gene manipulation steps of HSPC graft preparation significantly reduce the frequency of HSCs, thus necessitating large doses of HSPCs and reagents for the manipulation. Here, we identified a combination of small molecules, Resveratrol, UM729, and SR1 that preferentially expands CD34+CD133+CD90+ HSCs over other subpopulations of adult HSPCs in ex vivo culture. The preferential expansion enriches the HSCs in ex vivo culture, enhances the adhesion and results in a 6-fold increase in the long-term engraftment in NSG mice. Further, the culture enriched HSCs are more responsive to gene modification by lentiviral transduction and gene editing, increasing the frequency of gene-modified HSCs up to 10-fold in vivo. The yield of gene-modified HSCs obtained by the culture enrichment is similar to the sort-purification of HSCs and superior to Cyclosporin-H treatment. Our study addresses a critical challenge of low frequency of gene-modified HSCs in HSPC graft by developing and demonstrating a facile HSPC culture condition that increases the frequency of gene-modified cells in vivo. This strategy will improve the outcome of HSPC gene therapy and also simplify the gene manipulation process.

Nicotinamide promotes pancreatic differentiation through the dual inhibition of CK1 and ROCK kinases in human embryonic stem cells

Background

Vitamin B3 (nicotinamide) plays important roles in metabolism as well as in SIRT and PARP pathways. It is also recently reported as a novel kinase inhibitor with multiple targets. Nicotinamide promotes pancreatic cell differentiation from human embryonic stem cells (hESCs). However, its molecular mechanism is still unclear. In order to understand the molecular mechanism involved in pancreatic cell fate determination, we analyzed the downstream pathways of nicotinamide in the derivation of NKX6.1⁺ pancreatic progenitors from hESCs.

Methods

We applied downstream modulators of nicotinamide during the induction from posterior foregut to pancreatic progenitors, including niacin, PARP inhibitor, SIRT inhibitor, CK1 inhibitor and ROCK inhibitor. The impact of those treatments was evaluated by quantitative real-time PCR, flow cytometry and immunostaining of pancreatic markers. Furthermore, CK1 isoforms were knocked down to validate CK1 function in the induction of pancreatic progenitors. Finally, RNA-seq was used to demonstrate pancreatic induction on the transcriptomic level.

Results

First, we demonstrated that nicotinamide promoted pancreatic progenitor differentiation in chemically defined conditions, but it did not act through either niacin-associated metabolism or the inhibition of PARP and SIRT pathways. In contrast, nicotinamide modulated differentiation through CK1 and ROCK inhibition. We demonstrated that CK1 inhibitors promoted the generation of PDX1/NKX6.1 double-positive pancreatic progenitor cells. shRNA knockdown revealed that the inhibition of CK1α and CK1ε promoted pancreatic progenitor differentiation. We then showed that nicotinamide also improved pancreatic progenitor differentiation through ROCK inhibition. Finally, RNA-seq data showed that CK1 and ROCK inhibition led to pancreatic gene expression, similar to nicotinamide treatment.

Conclusions

In this report, we revealed that nicotinamide promotes generation of pancreatic progenitors from hESCs through CK1 and ROCK inhibition. Furthermore, we discovered the novel role of CK1 in pancreatic cell fate determination.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02426-2.

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.

Ex vivo expansion of hematopoietic stem cells: Finally transitioning from the lab to the clinic

Hematopoietic stem cells (HSCs) have been used for therapeutic purposes for decades in the form of autologous and allogeneic transplantation and are currently emerging as an attractive target for gene therapy. A low stem cell dose is a major barrier to the application of HSC therapy in several situations, primarily umbilical cord blood transplantation and gene modification. Strategies that promote ex vivo expansion of the numbers of functional HSCs could overcome this barrier, hence have been the subject of intense and prolonged research. Several ex vivo expansion strategies have advanced to evaluation clinical trials, which are showing favorable outcomes along with convincing safety signals. Preclinical studies have recently confirmed beneficial incorporation of ex vivo expansion into HSC gene modification protocols. Collectively, ex vivo HSC expansion holds promise for significantly broadening the availability of cord blood units for transplantation, and for optimizing gene therapy protocols to enable their clinical application.

Mechanistic Basis of ex Vivo Umbilical Cord Blood Stem Progenitor Cell Expansion

Umbilical cord blood (CB) transplantation has been used successfully in humans for three decades due to its rapid availability for patients lacking a suitable allogeneic donor, less stringent HLA matching requirements, and low rates of relapse and chronic graft-versus-host disease (GVHD). However, CB transplantation is associated with complications, such as delayed hematopoietic engraftment, graft failure, which increases infection and bleeding and causes longer hospital stays, and transplant-related mortality. The majority of these biological limitations are due to the unforeseeable functional potency of multipotent hematopoietic stem cells (HSCs), which reduce the predictability of successful transplantation; however, several strategies have been developed to increase the number of hematopoietic stem progenitor cells (HSPCs) infused during CB transplantation. This review primarily addresses the methods that promote ex vivo CB expansion within the context of symmetrical and asymmetrical HSC division and those that rely on epigenetic mechanisms, along with the reportedly most successful cytokine combinations. We also review recent clinical research on small molecules (StemRegenin-1, UM171, and nicotinamide) in ex vivo expanded CB and discuss yet unvalidated preclinical strategies. Expanding and transplanting CB graft enriched in HSPCs in a single CB unit is a particularly exciting prospect with the potential to improve the use and availability of CB grafts. Greater knowledge of optimal ex vivo expansion strategies, cell longevity, and graft potency will expand the scope of cellular therapies. Also the development of adequate ex vivo HSPC expansion strategies could bring expanded cord blood grafts to the forefront of transplant therapy and regenerative medicine.