Outcomes of acute leukemia patients transplanted with naive T cell–depleted stem cell grafts

BACKGROUND. Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality following allogeneic hematopoietic stem cell transplantation (HCT). In mice, naive T cells (T_N) cause more severe GVHD than memory T cells (T_M). We hypothesized that selective depletion of T_N from human allogeneic peripheral blood stem cell (PBSC) grafts would reduce GVHD and provide sufficient numbers of hematopoietic stem cells and T_M to permit hematopoietic engraftment and the transfer of pathogen-specific T cells from donor to recipient, respectively.METHODS. In a single-arm clinical trial, we transplanted 35 patients with high-risk leukemia with T_N-depleted PBSC grafts following conditioning with total body irradiation, thiotepa, and fludarabine. GVHD prophylactic management was with tacrolimus immunosuppression alone. Subjects received CD34-selected PBSCs and a defined dose of T_M purged of CD45RA⁺ T_N. Primary and secondary objectives included engraftment, acute and chronic GVHD, and immune reconstitution.RESULTS. All recipients of T_N-depleted PBSCs engrafted. The incidence of acute GVHD was not reduced; however, GVHD in these patients was universally corticosteroid responsive. Chronic GVHD was remarkably infrequent (9%; median follow-up 932 days) compared with historical rates of approximately 50% with T cell–replete grafts. T_M in the graft resulted in rapid T cell recovery and transfer of protective virus-specific immunity. Excessive rates of infection or relapse did not occur and overall survival was 78% at 2 years.CONCLUSION. Depletion of T_N from stem cell allografts reduces the incidence of chronic GVHD, while preserving the transfer of functional T cell memory.TRIAL REGISTRATION. ClinicalTrials.gov ({"type":"clinical-trial","attrs":{"text":"NCT 00914940","term_id":"NCT00914940"}}NCT 00914940).FUNDING. NIH, Burroughs Wellcome Fund, Leukemia and Lymphoma Society, Damon Runyon Cancer Research Foundation, and Richard Lumsden Foundation.     

The relationship between CD34+ stem cell dose and time to neutrophil recovery in autologous haematopoietic stem cell recipients—A single centre experience

A retrospective, observational study was performed of 112 patients who underwent autologous haematopoietic stem cell transplantation (ASCT) to determine the relationship between CD34+ stem cell dose and neutrophil engraftment. Importantly, a novel approach to more accurately calculate time to neutrophil engraftment was employed. The results demonstrated that a higher CD34+ stem cell dose was associated with faster neutrophil recovery (P?<?0.05). CD34+ stem cell dose using actual and ideal patient body weight were both equally predictive of neutrophil engraftment as were absolute and viable CD34+ measurements. The clinical implications for this relationship are limited with an increase in CD34+ stem cell dose by 1?×?10⁶/kg reducing the neutrophil engraftment time by only 3?h and 50?min. The median time to neutrophil recovery was 217?h (9 days and 1?h) and this relatively early engraftment time may be related to an early initiation of granulocyte colony-stimulating factor (G-CSF) on day +1 post-transplant. Female patients engrafted 17?h faster than their male counterparts on multi-variate analysis (P?<?0.05). Conditioning chemotherapy, bacteraemia, G-CSF dose/kg body weight and increasing age had no impact on time to neutrophil recovery.     

Hematopoietic stem cell development requires transient Wnt/β-catenin activity

Understanding how hematopoietic stem cells (HSCs) are generated and the signals that control this process is a crucial issue for regenerative medicine applications that require in vitro production of HSC. HSCs emerge during embryonic life from an endothelial-like cell population that resides in the aorta-gonad-mesonephros (AGM) region. We show here that β-catenin is nuclear and active in few endothelial nonhematopoietic cells closely associated with the emerging hematopoietic clusters of the embryonic aorta during mouse development. Importantly, Wnt/β-catenin activity is transiently required in the AGM to generate long-term HSCs and to produce hematopoietic cells in vitro from AGM endothelial precursors. Genetic deletion of β-catenin from the embryonic endothelium stage (using VE-cadherin-Cre recombinase), but not from embryonic hematopoietic cells (using Vav1-Cre), precludes progression of mutant cells toward the hematopoietic lineage; however, these mutant cells still contribute to the adult endothelium. Together, those findings indicate that Wnt/β-catenin activity is needed for the emergence but not the maintenance of HSCs in mouse embryos.     

Mesenchymal stem cell repair of knee chondral lesions北大核心CSCD

BACKGROUND AND OBJECTIVE As mesenchymal stem ceils have the capacity to differentiate into a variety of cells,many have explored the use of those cells for the treatment of chondral defects.This study used such cells to develop a three-dimensional,tissue-engi-neered construct (TEC),containing undifferentiated,synovial-derived mesenchymal cells,surrounded by extracellular matrices synthesized by the cells.     

Protein tyrosine phosphatase–σ regulates hematopoietic stem cell–repopulating capacity

Hematopoietic stem cell (HSC) function is regulated by activation of receptor tyrosine kinases (RTKs). Receptor protein tyrosine phosphatases (PTPs) counterbalance RTK signaling; however, the functions of receptor PTPs in HSCs remain incompletely understood. We found that a receptor PTP, PTPσ, was substantially overexpressed in mouse and human HSCs compared with more mature hematopoietic cells. Competitive transplantation of bone marrow cells from PTPσ-deficient mice revealed that the loss of PTPσ substantially increased long-term HSC-repopulating capacity compared with BM cells from control mice. While HSCs from PTPσ-deficient mice had no apparent alterations in cell-cycle status, apoptosis, or homing capacity, these HSCs exhibited increased levels of activated RAC1, a RhoGTPase that regulates HSC engraftment capacity. shRNA-mediated silencing of PTPσ also increased activated RAC1 levels in wild-type HSCs. Functionally, PTPσ-deficient BM cells displayed increased cobblestone area–forming cell (CAFC) capacity and augmented transendothelial migration capacity, which was abrogated by RAC inhibition. Specific selection of human cord blood CD34⁺CD38^–CD45RA^–lin^– PTPσ^– cells substantially increased the repopulating capacity of human HSCs compared with CD34⁺CD38^–CD45RA^–lin^– cells and CD34⁺CD38^–CD45RA^–lin^–PTPσ⁺ cells. Our results demonstrate that PTPσ regulates HSC functional capacity via RAC1 inhibition and suggest that selecting for PTPσ-negative human HSCs may be an effective strategy for enriching human HSCs for transplantation.     

Does myeloma genetic have an effect on stem cell mobilization?

BackgroundAutologous stem cell transplantation (ASCT) after induction treatment is the standard of care. Our understanding of myeloma genetics has been very limited and its effect to stem cell mobilization is not widely investigated. We aimed to investigate the effect of genetic abnormalities on stem cell mobilization in myeloma.MethodsThe data of 150 MM patients who underwent stem cell mobilization at our center between 2009–2020 were included and analyzed retrospectively. Pre-treatment bone marrow cytogenetics and fluorescence in situ hybridization tests were performed for each patient.ResultsGroups were divided into two as patients with normal cytogenetic and abnormal cytogenetic. No difference observed between groups regarding age, gender and ECOG (p = 0.4; p = 0.2; p = 0.3). Groups were similar concerning myeloma characteristics, received treatment and treatment response. Median CD34+ cells/kg harvested was 444(2−11.29) in normal cytogenetic group whereas it was 4,8(2.4−8.6) in abnormal cytogenetic group(p = 0.2). Optimal CD34+ cells level achievement was 73 (67 %) in normal cytogenetic group while it was 25(71.4 %) in abnormal cytogenetic group(p = 0.6). Neutrophil and platelet engraftment durations were similar among cytogenetic groups (p = 0.7; p = 0.9). R-ISS based groups were also did not differ regarding harvested CD34+ cells and achievement optimal CD34 level (p = 0.79, p = 0.74). Engraftment durations for neutrophil and platelet were comparable between R-ISS based groups (p = 0.59, p = 0.65)ConclusionsHere we were not able to find any impact of genetic abnormalities on stem cell mobilization in myeloma patients. Expanded studies can aid to identify the effect of particular genetic anomalies on the stem cell mobilization.     

What is the role of apheresis technology in stem cell transplantation?

Since the demonstration that hematopoietic cells are present in circulating blood, peripheral blood stem cell transplantation (PBSCT) has become an area of interest. The invention of growth factors such as the granulocyte colony-stimulating factor (G-CSF) and the availability of apheresis techniques allowed the wide application of peripheral blood stem cells (PBSC) in both autologous and allogeneic hematopoietic stem cell transplantation settings. It has been since 1986 that clinically introduced, peripheral blood stem cells replaced bone marrow as a stem-cell source to nearly 100% in the autologous and to approximately 75% in the allogeneic transplantation setting. During this period of time, remarkable development occurred in both stem cell mobilizing agents (i.e. CXCR4 antagonists) and apheresis techniques. Currently, apheresis technology is being increasingly used in not only for collection of PBSC or blood product support, but also for treatment and/or prevention of several transplantations related complications. Apheresis technology also allows to manipulate stem cells and thus provides opportunity to curative treatment of certain diseases.     

The CDK inhibitors: potential targets for therapeutic stem cell manipulations?

Therapies involving adult stem cells are dependent upon sufficient expansion of these cells to repopulate or replace the diseased tissue and are consequently hindered by their relatively quiescent phenotype. Cellular proliferation is governed by the cyclin-dependent kinases, which in a complex with a corresponding cyclin, phosphorylate a number of downstream mediators to drive the cell through the cell cycle. In turn, biochemical activities of the cyclin-dependent kinases are regulated by two families of cyclin-dependent kinase inhibitors, which have been shown to be potent cell intrinsic blocks of adult stem cell proliferation in multiple tissue types. In contrast to normal stem cells, inappropriate regulation of the cell cycle in cancer stem cells may underlie tumorigenesis and failure of conventional chemotherapeutics to fully eradicate a tumor. Thus, definition of the roles of the cyclin-dependent kinase inhibitors in normal and cancer stem cells may permit the development of novel strategies for adult stem cell expansion and therapies specifically targeted to cancer stem cells.     

Autologous mesenchymal stem cell–derived dopaminergic neurons function in parkinsonian macaques

A cell-based therapy for the replacement of dopaminergic neurons has been a long-term goal in Parkinson’s disease research. Here, we show that autologous engraftment of A9 dopaminergic neuron-like cells induced from mesenchymal stem cells (MSCs) leads to long-term survival of the cells and restoration of motor function in hemiparkinsonian macaques. Differentiated MSCs expressed markers of A9 dopaminergic neurons and released dopamine after depolarization in vitro. The differentiated autologous cells were engrafted in the affected portion of the striatum. Animals that received transplants showed modest and gradual improvements in motor behaviors. Positron emission tomography (PET) using [¹¹C]-CFT, a ligand for the dopamine transporter (DAT), revealed a dramatic increase in DAT expression, with a subsequent exponential decline over a period of 7 months. Kinetic analysis of the PET findings revealed that DAT expression remained above baseline levels for over 7 months. Immunohistochemical evaluations at 9 months consistently demonstrated the existence of cells positive for DAT and other A9 dopaminergic neuron markers in the engrafted striatum. These data suggest that transplantation of differentiated autologous MSCs may represent a safe and effective cell therapy for Parkinson’s disease.     

Which regimen is better for stem cell mobilization of lymphoma patients?

Although chemotherapy combined with G-CSF is an effective method for hematopoietic stem cell mobilization, standard chemotherapy protocol leading to best stem cell yield is not defined. In our study, we aimed to assess the impact of chemotherapy choice on mobilization outcome in lymphoma patients. Patients were mobilized with cyclophosphamide (n:15), ASHAP (n:11) or VGEPP (n:12) protocols. Groups were similar according to collected CD34+ cell count, total nucleated cell count and median apheresis days. Five out of fifteen (33%) patients could not be mobilized in Cy group but there was only one failed mobilization attempt in both salvage groups (9% with ASHAP vs 8% with VGEPP). In conclusion, we showed that VGEPP and ASHAP are safe protocols in terms of stem cell mobilization and have similar mobilization capacity as cyclophosphamide alone.     

Musashi2 sustains the mixed-lineage leukemia–driven stem cell regulatory program

Leukemia stem cells (LSCs) are found in most aggressive myeloid diseases and contribute to therapeutic resistance. Leukemia cells exhibit a dysregulated developmental program as the result of genetic and epigenetic alterations. Overexpression of the RNA-binding protein Musashi2 (MSI2) has been previously shown to predict poor survival in leukemia. Here, we demonstrated that conditional deletion of Msi2 in the hematopoietic compartment results in delayed leukemogenesis, reduced disease burden, and a loss of LSC function in a murine leukemia model. Gene expression profiling of these Msi2-deficient animals revealed a loss of the hematopoietic/leukemic stem cell self-renewal program and an increase in the differentiation program. In acute myeloid leukemia patients, the presence of a gene signature that was similar to that observed in Msi2-deficent murine LSCs correlated with improved survival. We determined that MSI2 directly maintains the mixed-lineage leukemia (MLL) self-renewal program by interacting with and retaining efficient translation of Hoxa9, Myc, and Ikzf2 mRNAs. Moreover, depletion of MLL target Ikzf2 in LSCs reduced colony formation, decreased proliferation, and increased apoptosis. Our data provide evidence that MSI2 controls efficient translation of the oncogenic LSC self-renewal program and suggest MSI2 as a potential therapeutic target for myeloid leukemia.     

Do tumor-suppressive mechanisms contribute to organism aging by inducing stem cell senescence?

Stem/progenitor cells ensure tissue and organism homeostasis and might represent a frequent target of transformation. Although these cells are potentially immortal, their life span is restrained by signaling pathways (p19-p53; p16-Rb) that are activated by DNA damage (telomere dysfunction, environmental stresses) and lead to senescence or apoptosis. Execution of these checkpoint programs might lead to stem cell depletion and organism aging, while their inactivation contributes to tumor formation.     

SDF-1α as a therapeutic stem cell homing factor in myocardial infarction

Myocardial infarction is associated with persistent muscle damage, scar formation and depressed cardiac performance. Recent studies have demonstrated the clinical significance of stem cell-based therapies after myocardial infarction with the aim to improve cardiac remodeling and function by inducing the reconstitution of functional myocardium and formation of new blood vessels. Stem cell homing signals play an important role in stem cell mobilization from the bone marrow to the ischemic cardiac environment and are therefore crucial for myocardial repair. To date, the most prominent stem cell homing factor is the chemokine SDF-1α/CXCL12. This protein was shown to be significantly upregulated in many experimental models of myocardial infarction and in patients suffering from ischemic cardiac diseases, suggesting the involvement in the pathophysiology of these disorders. A number of studies focused on manipulating SDF-1α and its receptor CXCR4 as central regulators of the stem cell mobilization process. Targeted expression of SDF-1α after myocardial infarction was shown to result in increased engraftment of bone marrow-derived stem cells into infarcted myocardium. This was accompanied by beneficial effects on cardiomyocyte survival, neovascularization and cardiac function. Thus, the SDF-1/CXCR4 axis seems to be a promising novel therapeutic approach to improve post-infarction therapy by attracting circulating stem cells to remain, survive and possibly differentiate in the infarct area. This review will summarize clinical trials of stem cell therapy in patients with myocardial infarction. We further discuss the basic findings about SDF-1α in stem cell recruitment and its therapeutic implications in experimental myocardial infarction.     

The plastic liver: differentiated cells,stem cells,every cell?

The liver is capable of full regeneration following several types and rounds of injury, ranging from hepatectomy to toxin-mediated damage. The source of this regenerative capacity has long been a hotly debated topic. The damage response that occurs when hepatocyte proliferation is impaired is thought to be mediated by oval/dedifferentiated progenitor cells, which replenish the hepatocyte and ductal compartments of the liver. Recently, reports have questioned whether these oval/progenitor cells truly serve as the facultative stem cell of the liver following toxin-mediated damage. In this issue of the JCI, Kordes and colleagues use lineage tracing to follow transplanted rat hepatic stellate cells, a resident liver mesenchymal cell population, in hosts that have suffered liver damage. Transplanted stellate cells repopulated the damaged rat liver by contributing to the oval cell response. These data establish yet another cell type of mesenchymal origin as the progenitor for the oval/ductular response in the rat. The lack of uniformity between different damage models, the extent of the injury to the liver parenchyma, and potential species-specific differences might be at the core of the discrepancy between different studies. Taken together, these data imply a considerable degree of plasticity in the liver, whereby several cell types can contribute to regeneration.