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Microglia, the immune sentinel of the central nervous system (CNS), are generated from yolk sac erythromyeloid progenitors that populate the developing CNS. Interestingly, a specific type of bone marrow-derived monocyte is able to express a yolk sac microglial signature and populate CNS in disease. Here we have examined human bone marrow (hBM) in an attempt to identify novel cell sources for generating microglia-like cells to use in cell-based therapies and in vitro modeling. We demonstrate that hBM stroma harbors a progenitor cell that we name stromal microglial progenitor (STR-MP). STR-MP single-cell gene analysis revealed the expression of the consensus genetic microglial signature and microglial-specific genes present in development and CNS pathologies. STR-MPs can be expanded and generate microglia-like cells in vitro, which we name stromal microglia (STR-M). STR-M cells show phagocytic ability, classically activate, and survive and phagocyte in human brain tissue. Thus, our results reveal that hBM harbors a source of microglia-like precursors that can be used in patient-centered fast derivative approaches., (© 2020 The Authors. STEM CELLS TRANSLATIONAL MEDICINE published by Wiley Periodicals LLC on behalf of AlphaMed Press.)

Skeletal stem cells (SSC) are a sub-population of bone marrow stromal cells that reside in postnatal bone marrow with osteogenic, chondrogenic and adipogenic differentiation potential. SSCs reside only in the bone marrow and have organisational and regulatory functions in the bone marrow microenvironment and give rise to the haematopoiesis-supportive stroma. Their differentiation capacity is restricted to skeletal lineages and therefore the term SSC should be clearly distinguished from mesenchymal stem cells which are reported to exist in extra-skeletal tissues and, critically, do not contribute to skeletal development. SSCs are responsible for the unique regeneration capacity of bone and offer unlimited potential for application in bone regenerative therapies. A current unmet challenge is the isolation of homogeneous populations of SSCs, in vitro , with homogeneous regeneration and differentiation capacities. Challenges that limit SSC isolation include a) the scarcity of SSCs in bone marrow aspirates, estimated at between 1 in 10–100,000 mononuclear cells; b) the absence of specific markers and thus the phenotypic ambiguity of the SSC and c) the complexity of bone marrow tissue. Microfluidics provides innovative approaches for cell separation based on bio-physical features of single cells. Here we review the physical principles underlying label-free microfluidic sorting techniques and review their capacity for stem cell selection/sorting from complex (heterogeneous) samples. [ABSTRACT FROM AUTHOR]

We studied the process of trans-differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs) into insulin-producing cells. Streptozotocin (STZ)-induced diabetic rat model was used to study the effect of portal vein transplantation of these insulin-producing cells on blood sugar levels. The BM-MSCs were differentiated into insulin-producing cells under defined conditions. Real-time PCR, immunocytochemistry and glucose challenge were used to evaluate in vitro differentiation. Flow cytometry showed that hBM-MSCs were strongly positive for CD44, CD105 and CD73 and negative for hematopoietic markers CD34, CD38 and CD45. Differentiated cells expressed C-peptide as well as β-cells specific genes and hormones. Glucose stimulation increased C-peptide secretion in these cells. The insulin-producing, differentiated cells were transplanted into the portal vein of STZ-induced diabetic rats using a Port-A catheter. The insulin-producing cells were localized in the liver of the recipient rat and expressed human C-peptide. Blood glucose levels were reduced in diabetic rats transplanted with insulin-producing cells. We concluded that hBM-MSCs could be trans-differentiated into insulin-producing cells in vitro. Portal vein transplantation of insulin-producing cells alleviated hyperglycemia in diabetic rats. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) may be employed to support hematopoietic reconstitution and mitigate graft- vs.-host disease (GVHD) in transplantation of hematopoietic stem cells (HSCs). The aim of this study was to explore the feasibility and safety of cotransplantation culture-expanded MSCs and HSCs from the same human leukocyte antigen (HLA)-identical sibling donor in Chinese patients with hematologic diseases. Bone marrow mononuclear cells from healthy donors were cultured and expanded ex vivo. Immunophenotype, adipogenic and osteogenic differentiation potential, and karyotype of the harvested MSCs were detected on those who had been cotransplanted with HSCs and MSCs from the same donor. Hematopoietic reconstitutions, complications, and clinical outcomes were observed after cotransplantation in these patients. (1.77 ± 0.40) × 106/kg (donor’s weight) MSCs were successfully expanded from 23.6 ± 5.96 ml of bone marrow samples. They had normal karyotypes with bi-lineages differentiation potential, and were CD73, CD90, and CD105 positive. Twelve patients underwent cotransplantation with no observable adverse response during and after the infusion of MSCs. Hematopoietic reconstitutions were rapid. Two patients developed grade II–IV acute GVHD, and two extensive chronic GVHD. Four patients suffered from cytomegalovirus infection but were cured eventually. Up to now, seven patients have been followed as long as 29–57 months and five patients died. It is concluded that MSCs can be expanded effectively by culture and it is safe and feasible to cotransplant patients with allogenic culture-expanded MSCs and HSCs. [ABSTRACT FROM AUTHOR]

Abstract: Since stem cells can differentiate into hepatocyte, stem cell-based therapy becomes a potential alternative treatment for terminal liver diseases. However, an appropriate source of human mesenchymal stem cells (hMSCs) for hepatocytes has not yet been clearly elucidated. The aim of the present study was to investigate the in vitro biological characterization and hepatic differentiation potential of human amniotic fluid-derived mesenchymal stem cells (AF-hMSCs) and human bone marrow-derived mesenchymal stem cells (BM-hMSCs). Our results show that AF-hMSCs possess higher proliferation and self-renewal capacity than BM-hMSCs. Cytogenetic studies indicate that AF-hMSCs are as genetically stabile as BM-hMSCs. Following incubation with specific hepatogenic agents, AF-hMSCs showed a higher hepatic differentiation potential than BM-hMSCs. Expression of several liver-specific markers was significantly greater in AF-hMSCs than in BM-hMSCs, as shown by real time RT-PCR and immunofluorescence (IF). In conclusion, AF-hMSCs possess superior potential for hepatic differentiation, making them more suitable for diverse terminal liver diseases. [Copyright &y& Elsevier]

Time-dependent variations in clock gene expression have recently been observed in mouse hematopoietic cells, but the activity of these genes in human bone marrow (BM) has so far not been investigated. Since such data can be of considerable clinical interest for monitoring the dynamics in stem/progenitor cells, the authors have studied mRNA expression of the clock genes hPer1, hPer2, hCry1, hCry2, hBmal1, hRev-erb α, and hClock in human hematopoietic CD34-positive (CD34+) cells. CD34+ cells were isolated from the BM samples obtained from 10 healthy men at 6 times over 24 h. In addition, clock gene mRNA expression was analyzed in the whole BM in 3 subjects. Rhythms in serum cortisol, growth hormone, testosterone, and leukocyte counts documented that subjects exhibited standardized circadian patterns. All 7 clock genes were expressed both in CD34+ cells and the whole BM, with some differences in magnitude between the 2 cell populations. A clear circadian rhythm was shown for hPer1, hPer2, and hCry2 expression in CD34+ cells and for hPer1 in the whole BM, with maxima from early morning to midday. Similar to mouse hematopoietic cells, hBmal1 was not oscillating rhythmically. The study demonstrates that clock gene expression in human BM stem/progenitor cells may be developmentally regulated, with strong or weaker circadian profiles as compared to those reported in other mature tissues. [ABSTRACT FROM AUTHOR]

Current theory indicates that mitochondria were obtained 1.5 billion years ago from an ancient prokaryote. The mitochondria provided the capacity for aerobic respiration, the creation of the eukaryotic cell, and eventually complex multicellular organisms. Recent reports have found that mitochondria play essential roles in aging and determining lifespan. A variety of heritable and acquired diseases are linked to mitochondrial dysfunction. We report here that mitochondria are more dynamic than previously considered: mitochondria or mtDNA can move between cells. The active transfer from adult stem cells and somatic cells can rescue aerobic respiration in mammalian cells with nonfunctional mitochondria. [ABSTRACT FROM AUTHOR]

Abstract: Mesenchymal stem cells (MSCs) are found in a variety of tissues, including human bone marrow; secrete hematopoietic cytokines; support hematopoietic progenitors in vitro; and possess potent immunosuppressive properties. We hypothesized that cotransplantation of culture-expanded MSCs and hematopoietic stem cells (HSCs) from HLA-identical sibling donors after myeloablative therapy could facilitate engraftment and lessen graft-versus-host disease (GVHD); however, the safety and feasibility of this approach needed to be established. In an open-label, multicenter trial, we coadministered culture-expanded MSCs with HLA-identical sibling-matched HSCs in hematologic malignancy patients. Patients received either bone marrow or peripheral blood stem cells as the HSC source. Patients received 1 of 4 study-specified transplant conditioning regimens and methotrexate (days 1, 3, and 6) and cyclosporine as GVHD prophylaxis. On day 0, patients were given culture-expanded MSCs intravenously (1.0¿5.0 × 106/kg) 4 hours before infusion of either bone marrow or peripheral blood stem cells. Forty-six patients (median age, 44.5 years; range, 19¿61 years) received MSCs and HLA-matched sibling allografts. MSC infusions were well tolerated, without any infusion-related adverse events. The median times to neutrophil (absolute neutrophil count ¿0.500 × 109/L) and platelet (platelet count ¿20 × 109/L) engraftment were 14.0 days (range, 11.0¿26.0 days) and 20 days (range, 15.0¿36.0 days), respectively. Grade II to IV acute GVHD was observed in 13 (28%) of 46 patients. Chronic GVHD was observed in 22 (61%) of 36 patients who survived at least 90 days; it was extensive in 8 patients. Eleven patients (24%) experienced relapse at a median time to progression of 213.5 days (range, 14¿688 days). The probability of patients attaining disease- or progression-free survival at 2 years after MSC infusion was 53%. Cotransplantation of HLA-identical sibling culture-expanded MSCs with an HLA-identical sibling HSC transplant is feasible and seems to be safe, without immediate infusional or late MSC-associated toxicities. The optimal MSC dose and frequency of administration to prevent or treat GVHD during allogeneic HSC transplantation should be evaluated further in phase II clinical trials. [Copyright &y& Elsevier]