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Project description:Upon ex vivo culture, hematopoietic stem cells (HSCs) quickly lose potential and differentiate into progenitors. The identification of culture conditions that maintain the potential of HSCs ex vivo is therefore of high clinical interest. Here, we demonstrate that the potential of murine and human HSCs is maintained when cultivated for 2 days ex vivo at a pH of 6.9, in contrast to cultivation at the commonly used pH of 7.4. When cultivated at a pH of 6.9, HSCs remain smaller, less metabolically active, less proliferative and show enhanced reconstitution ability upon transplantation compared to HSC cultivated at pH 7.4. HSCs kept at pH 6.9 show an attenuated polyamine pathway. Pharmacological inhibition of the polyamine pathway in HSCs cultivated at pH 7.4 with DFMO mimics phenotypes und potential of HSCs cultivated at pH 6.9. Ex-vivo exposure to a pH of 6.9 is therefore a positive regulator of HSC function by reducing polyamines. These findings might improve HSC short-term cultivation protocols for transplantation and gene therapy interventions.
| S-SCDT-10_15252-EMBR_202255373 | biostudies-other
Project description:The scarcity of hematopoietic stem cells (HSCs) restricts their use in both clinical settings and experimental research. Here, we examined a recently developed method for expanding rigorously purified murine HSCs ex vivo. Input HSCs displayed varying potential for ex vivo self-renewal, with alternative outcomes revealed by single cell multimodal RNA- and ATAC-seq profiling. While most HSC progeny offered only transient in vivo reconstitution, these cells efficiently rescued mice from lethal myeloablation. The amplification of functional HSC activity allowed for long-term multilineage engraftment in unconditioned hosts that somewhat surprisingly associated with a return of HSCs to quiescence. Thereby, our findings identify several key considerations for ex vivo HSC expansion, with major implications also for assessment of normal HSC activity.
2023-11-08 | GSE234906 | GEO
Project description:In response to myeloablative stresses, HSCs are rapidly activated to replenish myeloid progenitors, while maintaining full potential of self-renewal to ensure life-long hematopoiesis. However, the key factors that orchestrate HSC activities during physiological stresses remain largely unknown. Here we report that Med23 controls the myeloid potential of activated HSCs. Ablation of Med23 in hematopoietic system leads to lymphocytopenia. Med23- deficient HSCs undergo myeloid-biased differentiation and lose the self-renewal capacity. Interestingly, Med23-deficient HSCs are much easier to be activated in response to physio- logical stresses. Mechanistically, Med23 plays essential roles in maintaining stemness genes expression and suppressing myeloid lineage genes expression. Med23 is downregulated in HSCs and Med23 deletion results in better survival under myeloablative stress. Altogether, our findings identify Med23 as a gatekeeper of myeloid potential of HSCs, thus providing unique insights into the relationship among Med23-mediated transcriptional regulations, the myeloid potential of HSCs and HSC activation upon stresses.
2018-07-14 | GSE112008 | GEO
Project description:Hematopoietic stem cells (HSCs) in the fetal liver mature from pre-HSCs that originate in the major arteries of the embryo. To generate HSCs from other cell sources it will be necessary to reproduce the maturation of HSCs from pre-HSCs ex vivo. We refined the markers used to purify pre-HSCs and HSCs matured ex vivo, and compared the transcriptomes of pre-HSCs, ex vivo matured HSCs, and fetal liver HSCs. We found that maturation of pre-HSCs into HSCs in vivo or ex vivo is accompanied by the downregulation of genes involved in embryonic development and vasculogenesis, and upregulation of genes involved in hematopoietic organ development, lymphoid development, and immune responses. Ex vivo matured HSCs more closely resemble fetal liver HSCs than pre-HSCs, but are not their molecular equivalents. We show that functional ex vivo-matured and fetal liver HSCs increase the expression of programmed death ligand 1 (PD-L1). PD-L1 does not mark all pre-HSCs, but cell surface PD-L1 was present on functional HSCs after ex vivo culture. PD-L1 signaling, however, is not required for engraftment of embryonic HSCs. Hence, up-regulation of PD-L1 is a correlate of, but not a requirement for HSC maturation.
2017-12-26 | GSE104689 | GEO
Project description:Maintaining proteostasis is key to resisting stress and to promoting healthy aging. Proteostasis is necessary to preserve stem cell function, but little is known about the mechanisms that regulate proteostasis during stress in stem cells, and whether disruptions in proteostasis contribute stem cell aging is largely unexplored. We determined that ex vivo cultured mouse and human hematopoietic stem cells (HSCs) rapidly increase protein synthesis. This challenge to HSC proteostasis was associated with nuclear accumulation of Hsf1, and deletion of Hsf1 impaired HSC maintenance ex vivo. Strikingly, supplementing cultures with small molecules that enhance Hsf1 activation partially suppressed protein synthesis, rebalanced proteostasis, and supported retention of HSC serial reconstituting activity. Although Hsf1 was dispensable for young adult HSCs in vivo, Hsf1 deficiency increased protein synthesis and impaired the reconstituting activity of middle-aged HSCs. Hsf1 thus promotes proteostasis and the regenerative activity of HSCs in response to culture stress and aging.
2021-07-11 | GSE179412 | GEO
Project description:Maintaining proteostasis is key to resisting stress and to promoting healthy aging. Proteostasis is necessary to preserve stem cell function, but little is known about the mechanisms that regulate proteostasis during stress in stem cells, and whether disruptions in proteostasis contribute stem cell aging is largely unexplored. We determined that ex vivo cultured mouse and human hematopoietic stem cells (HSCs) rapidly increase protein synthesis. This challenge to HSC proteostasis was associated with nuclear accumulation of Hsf1, and deletion of Hsf1 impaired HSC maintenance ex vivo. Strikingly, supplementing cultures with small molecules that enhance Hsf1 activation partially suppressed protein synthesis, rebalanced proteostasis, and supported retention of HSC serial reconstituting activity. Although Hsf1 was dispensable for young adult HSCs in vivo, Hsf1 deficiency increased protein synthesis and impaired the reconstituting activity of middle-aged HSCs. Hsf1 thus promotes proteostasis and the regenerative activity of HSCs in response to culture stress and aging.
2021-07-11 | GSE179413 | GEO
Project description:Hematopoietic stem cell transplantation (HSCT) is successfully applied since the late 1950s, however, its efficacy still needs to be improved. A promising strategy is to transplant high numbers of pluripotent hematopoietic stem cells (HSCs). Therefore, an advanced ex vivo culture system is needed that supports the proliferation and maintains the pluripotency of HSC to override possible limitations in cell numbers gained from donors. To model the natural HSC niche in vitro and thus, to amplify high numbers of undifferentiated HSCs, we used an optimized HSC cell culture medium in combination with artificial 3D bone marrow-like scaffolds made of polydimethylsiloxane (PDMS). After 14 days in vitro (DIV) cell culture, we performed transcriptome and proteome analysis of the whole cell populations. Ingenuity pathway analysis (IPA) indicated that our 3D PDMS cell culture scaffolds activated interleukin, SREBP, mTOR and FOXO signaling pathways as well as the HSC metabolism, which we confirmed by ELISA, Western blot and metabolic flux analysis. These molecular signaling pathways and HSC metabolism are well known to promote the expansion HSCs and are involved in their pluripotency maintenance. After selection and enrichment of immature CD34-positive/CD38-negative HSCs using FACS sorting, we could confirm our findings by another proteome analysis followed by IPA. Thus, we could show that our 3D bone marrow-like PDMS scaffolds activate key molecular signaling pathways to amplify the numbers of undifferentiated HSC efficiently ex vivo.
2021-11-10 | PXD025849 | Pride
Project description:Hematopoietic stem cells (HSCs) have some unique physiological adaptations to maintain blood cell production and deal with stress responses throughout life. To maintain such adaptations, HSCs are particularly dependent on maintaining a tightly controlled protein translation rate. However, how HSCs fine tune protein translation has not been fully described. In this study, we report the role of TRMT6 in regulating HSC function in adult hematopoiesis. Trmt6-null mice became moribund due to hematopoietic failure with pancytopenia in the blood and bone marrow 4 to 8 weeks after Trmt6 deletion. Trmt6-deleted bone marrow cells failed to repopulate hemoablated recipients in competitive transplantation experiments. Loss of TRMT6 resulted in an abnormally high rate of recruitment of quiescent hematopoietic stem cells (HSCs) into the cell cycle. Cycling HSCs produced progenitors at the expense of self-renewal, which led to the exhaustion of the HSC pool. Mechanistically, mTORC1 signaling pathway was highly upregulated in HSC-enriched cell populations after Trmt6 deletion by single cell RNA-seq analysis. Furthermore, TRMT6 was required for tRNA m1A modification required for HSC quiescence and self-renewal. Our data indicate that TRMT6 promotes the expression of TSC1, fine-tuning mTORC1 signaling level which is essential for HSC maintenance and self-renewal in adult hematopoiesis.
2024-06-03 | GSE230711 | GEO
Project description:Although practiced clinically for more than 40 years, the use of hematopoietic stem cell (HSC) transplants remains limited by the ability to expand these cells ex vivo. An unbiased screen with primary human HSCs identified a purine derivative, StemRegenin 1 (SR1), that promotes the ex vivo expansion of CD34+ cells. Culture of HSCs with SR1 led to a 50-fold increase in cells expressing CD34 and a 17-fold increase in cells that retain the ability to engraft immunodeficient mice. Mechanistic studies show that SR1 acts by antagonizing the aryl hydrocarbon receptor (AHR). The identification of SR1 and AHR modulation as a means to induce ex vivo HSC expansion should facilitate the clinical use of HSC therapy. LGC006, a less potent SR1 analog, was also examined. KEYWORDS: two compounds, multiple doses, one time point two compounds, multiple doses, one time point
2011-04-04 | E-GEOD-28359 | biostudies-arrayexpress
Project description:Hematopoietic stem cells (HSCs) are identified by their ability to sustain prolonged blood cell production in vivo, although recent evidence suggests that durable self-renewal (DSR) is shared by HSC subtypes with distinct self-perpetuating differentiation programs. Net expansions of DSR-HSCs occur in vivo, but molecularly defined conditions that support similar responses in vitro are lacking. We hypothesized that this might require a combination of factors that differentially promote HSC viability, proliferation and self-renewal. We now demonstrate that HSC survival and maintenance of DSR potential is variably supported by different Steel factor (SF)-containing cocktails with similar HSC-mitogenic activities. In addition, stromal cells produce other factors, including nerve growth factor and collagen 1, that can antagonize the apoptosis of initially quiescent adult HSCs and, in combination with SF and interleukin-11, produce >15-fold net expansions of DSR-HSCs ex vivo within 7 days. These findings suggest a new molecular basis for HSC control and expansion. Adult mouse bone marrow CD45+EPCR+CD48-CD150+ cells were used in a total of 4 conditions (fresh, 6 hour stimulation with SF+IL-11+UG26 CM, UG26 CM only, SF+IL-11) with 2 technical replicates per condition.
2014-05-01 | E-GEOD-57220 | biostudies-arrayexpress