Project description:Glycogen synthase kinase-3β (GSK-3β) has been recently identified as an important regulator of stem cell function. In vitro studies show that GSK-3β inhibition delays proliferation of human haematopoietic progenitor cells while increasing numbers of late dividing multipotent progenitors. Gene expression analysis revealed that GSK-3β inhibition modulates the expression of a subset of genes that are transcriptional targets for cytokines. GSK-3β inhibition antagonised down-regulation of genes encoding cyclin dependent kinase inhibitor p57 and a member of the growth arrest and DNA damage 45 family, GADD45B as well as up-regulation of cyclin D1 by cytokines, providing a possible mechanism for the BIO-induced delay in cell cycle progression. Surprisingly, inhibition of GSK-3β earlier shown to prevent β-catenin degradation and promote the nuclear accumulation of β-catenin was not sufficient to activate its transcriptional targets in haematopoietic stem cells. GSK-3β inhibition up-regulated the expression of a several positive regulators of stem cell function suppressed during cytokine-induced proliferation. The data supports a clinical role for GSK-3β inhibition to improve engraftment efficiency of ex vivo expanded stem cells.
Project description:Glycogen synthase kinase-3β (GSK-3β) has been recently identified as an important regulator of stem cell function. In vitro studies show that GSK-3β inhibition delays proliferation of human haematopoietic progenitor cells while increasing numbers of late dividing multipotent progenitors. Gene expression analysis revealed that GSK-3β inhibition modulates the expression of a subset of genes that are transcriptional targets for cytokines. GSK-3β inhibition antagonised down-regulation of genes encoding cyclin dependent kinase inhibitor p57 and a member of the growth arrest and DNA damage 45 family, GADD45B as well as up-regulation of cyclin D1 by cytokines, providing a possible mechanism for the BIO-induced delay in cell cycle progression. Surprisingly, inhibition of GSK-3β earlier shown to prevent β-catenin degradation and promote the nuclear accumulation of β-catenin was not sufficient to activate its transcriptional targets in haematopoietic stem cells. GSK-3β inhibition up-regulated the expression of a several positive regulators of stem cell function suppressed during cytokine-induced proliferation. The data supports a clinical role for GSK-3β inhibition to improve engraftment efficiency of ex vivo expanded stem cells. Total RNA was isolated from three groups following expansion of CD34+ cells in cytokikes and then treatment with BIO, as described below.
Project description:Modulating signaling pathways including Wnt and Hippo can induce cardiomyocyte proliferation in vivo. Applying these signaling modulators to human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in vitro can expand CMs only to modest extent (< 5-fold). Here, we demonstrate massive expansion of hiPSC-CMs in vitro (i.e. 100-250-fold) by glycogen synthase kinase-3β (GSK-3β) inhibition using CHIR99021 and concurrent removal of cell-cell contact. We show GSK-3β inhibition suppresses CM maturation while contact removal prevents CMs from cell cycle exit. Remarkably, contact removal enabled 10-to-25-times greater expansion beyond GSK-3β inhibition alone. Mechanistically, cell cycle re-activation required both LEF/TCF activity and AKT phosphorylation, but it was independent from Yes associated protein (YAP) activity. Engineered heart tissues from expanded hiPSC-CMs showed the comparable contractility to those from unexpanded hiPSC-CMs, demonstrating uncompromised cellular functionality after expansion. In sum, we uncovered a molecular interplay that enables massive expansion hiPSC-CMs for large-scale drug screening and tissue engineering.
Project description:Ex-vivo expanded mesenchymal stromal cells (MSCs) are increasingly used for paracrine support of hematopoietic stem cell (HSC) regeneration, but inconsistent outcomes have been the huddle for on-going clinical trials. Here, we hypothesized that the heterogeneity in the niche activity of manufactured MSCs can be a parameter for variable outcomes in MSC-based cell therapy. We first screened MSC culture medium and found that serum batches caused larger variations in colony forming unit-fibroblast (CFU-F) content of MSCs than individual donor variations. The culture conditions supporting high (stimulatory) and low (non-stimulatory) CFU-F caused distinct niche activity of MSCs; MSCs under stimulatory condition exhibited higher level expression of cross-talk molecules (Jagged-1 and CXCL-12) and higher support for HSCS during long-term culture than MSCs under non-stimulatory culture. Moreover, the effects of MSCs enhancing hematopoietic engraftment were only visible when HSCs were co-transplanted with MSCs expanded under stimulatory, but not non-stimulatory conditions. However, these differences of MSCs were readily reversed by switching the culture mediums, indicating their distinct functional state, rather than clonal heterogeneity. Accordingly, transcriptomic analysis showed distinct gene set enrichment between the different MSCs and revealed distinct upstream signaling pathways such as inhibition of P53 and activation of ATF4 for MSCs under stimulatory conditions. Taken together, our study shows that the heterogeneity in the niche activity of MSCs can be created during ex-vivo expansion to cause a difference in the hematopoietic engraftment and raise the possibility that MSCs can be pre-screened for more predictable outcomes in clinical trials of MSCs. Total RNA obtained from isolated human mesenchymal stromal cells. To compare stimulatory (SS) serum and non-stimulatory (NSS) serums, MSCs had been maintained in each serum media were sub-cultured for at least two passages before analysis.
Project description:Transplantation with low numbers of hematopoietic stem cells (HSCs), found in many of the publically accessible cryopreserved umbilical cord blood (UCB) units, leads to delayed time to engraftment, high graft failure rates, and early mortality in many patients. A chemical screen in zebrafish identified the prostaglandin compound, 16,16 dimethyl prostaglandin E2 (dmPGE2), to be a critical regulator of hematopoietic stem cell homeostasis. We hypothesized that an ex vivo modulation with dmPGE2 prior to transplantation would lead to enhanced engraftment by increasing the “effective” dose of hematopoietic stem cells (HSCs) in cord blood. A phase I trial of reduced-intensity double UCB transplantation was performed to evaluate safety, rates of engraftment and fractional chimerism of dmPGE2 enhanced UCB units. To explore potential causes of the lack of enhanced efficacy in the first cohort, we characterized HSCs to determine whether the prostaglandin pathway was being activated under the ex vivo incubation conditions (4°C, 10µM dmPGE2, 60 minutes). Incubation conditions were identified (37°C, 10µM dmPGE2, 120 minutes) that maximize the activation of the prostaglandin pathway by dmPGE2 in human CD34+ cells. Isolated human CD34+ from umbilical cord blood were incubated ex vivo in Stem Span media with 10uM 16,16-dmPGE2 or DMSO. Two treatment conditions were evaluated (4 deg C for 1 hour, 37 deg C for 2 hours) with either 3 or 7 biological replicates at each condition. Total RNA was isolated post incubation and analyzed on Affymetrix microarrays for pathway activation.
Project description:The Notch signaling pathway plays a critical role in regulating the proliferation and differentiation of stem and progenitor cells including hematopoietic stem and progenitor cells (HSPCs). Notch receptors and ligands are expressed in BM stromal and hematopoietic cells. A large body of evidence has demonstrated that activating Notch signaling enhances HSCs self-renewal and facilitates its expansion ex vivo. We report that an endothelium-targeted soluble Notch ligand, the DSL domain of mouse Delta-like 1 fused with a RGD motif (mD1R), efficiently promotes the expansion ex vivo of mouse bone marrow HSPCs in a Notch signaling and endocytosis dependent manner. HSPCs expanded in the presence of mD1R kept long-term HSPC repopulation capacity. We used microarrays to compare the gene expression profiles of HSPCs expanded in the presence of PBS and mD1R. KSL cells were plated on Human umbilical vein endothelial cells (HUVECs) and cultured in a serum-free medium supplemented with a cocktail containing 5 types of mouse cytokines (m5GF) in the presence of PBS or mD1R for 7 days. Then KSL cells were sorted from these cultured hematopoietic cells for RNA extraction and hybridization on Affymetrix microarrays. The experiments were repeated 3 times.
Project description:The Notch signaling pathway plays a critical role in regulating the proliferation and differentiation of stem and progenitor cells including hematopoietic stem and progenitor cells (HSPCs). Notch receptors and ligands are expressed in BM stromal and hematopoietic cells. A large body of evidence has demonstrated that activating Notch signaling enhances HSCs self-renewal and facilitates its expansion ex vivo. We report that an endothelium-targeted soluble Notch ligand, the DSL domain of mouse Delta-like 1 fused with a RGD motif (mD1R), efficiently promotes the expansion ex vivo of mouse bone marrow HSPCs in a Notch signaling and endocytosis dependent manner. HSPCs expanded in the presence of mD1R kept long-term HSPC repopulation capacity. We used microarrays to compare the gene expression profiles of HSPCs expanded in the presence of PBS and mD1R.
Project description:Ex-vivo expanded mesenchymal stromal cells (MSCs) are increasingly used for paracrine support of hematopoietic stem cell (HSC) regeneration, but inconsistent outcomes have been the huddle for on-going clinical trials. Here, we hypothesized that the heterogeneity in the niche activity of manufactured MSCs can be a parameter for variable outcomes in MSC-based cell therapy. We first screened MSC culture medium and found that serum batches caused larger variations in colony forming unit-fibroblast (CFU-F) content of MSCs than individual donor variations. The culture conditions supporting high (stimulatory) and low (non-stimulatory) CFU-F caused distinct niche activity of MSCs; MSCs under stimulatory condition exhibited higher level expression of cross-talk molecules (Jagged-1 and CXCL-12) and higher support for HSCS during long-term culture than MSCs under non-stimulatory culture. Moreover, the effects of MSCs enhancing hematopoietic engraftment were only visible when HSCs were co-transplanted with MSCs expanded under stimulatory, but not non-stimulatory conditions. However, these differences of MSCs were readily reversed by switching the culture mediums, indicating their distinct functional state, rather than clonal heterogeneity. Accordingly, transcriptomic analysis showed distinct gene set enrichment between the different MSCs and revealed distinct upstream signaling pathways such as inhibition of P53 and activation of ATF4 for MSCs under stimulatory conditions. Taken together, our study shows that the heterogeneity in the niche activity of MSCs can be created during ex-vivo expansion to cause a difference in the hematopoietic engraftment and raise the possibility that MSCs can be pre-screened for more predictable outcomes in clinical trials of MSCs.
Project description:The identification of small molecules which either increase the number and/or enhance the activity of CD34+ hematopoietic stem and progenitor cells (HSPCs) during ex-vivo expansion has remained challenging. Applying an unbiased in vivo chemical screen in a transgenic (c-myb:EGFP) zebrafish embryo model, histone deacetylase inhibitors (HDACI) (valproic acid, resminostat and entinostat) were shown to significantly amplify the number of phenotypic hematopoietic precursors. The identified HDACIs were confirmed to significantly enhance also the expansion of human HSPCs during ex vivo treatment. Long-term functionality of ex vivo expanded human HSPCs was verified in a xenotransplantation model using NSG mice. However, the HDACI induced proliferation of HSPCs was associated with short-term functional changes. One of the identified hits, valproic acid (VPA), increased the adhesion capacity of CD34+ cells on primary mesenchymal stromal cells and reduced their chemokine-mediated migration capacity in vitro. In line with the reduced migratory potential in vitro, homing as well as early engraftment of VPA treated human CD34+ cells was significantly impaired in the xenotransplantation model. Our data confirms that HDACI treatment leads to a net expansion of HSPCs cells with long-term engraftment potential across different species. However impaired homing and short-term-engraftment has to be kept in mind when designing clinical transplantation protocols. In addition, our gene expression analysis (RNA-Seq) revealed expression of several genes that were altered in CD34+ cells by VPA treatment including cell adhesion molecules and Notch and wnt genes which has been shown to be involved in preservation of stem cell properties.
Project description:To analyze the roles of GSK-3β in podocytes, GSK-3β knockdown lentivirus by Clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein (Cas)9 was applied to establish stable cell lines. Phosphoproteome and proteome evaluation was conducted using TMT labeled LC-MS/MS technologies.