Stem cells and development最新文献

Exposure to high-dose radiation often results in hematopoietic acute radiation syndromes, leading to early mortality, while current therapies for patients exposed to lethal radiation doses are limited. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have shown promise in tissue repair and regeneration but have not been well investigated for mitigating high-dose radiation damage. We previously demonstrated that human or murine MSC-EVs can reverse bone marrow injury caused by mild or moderate radiation. The current study evaluated the therapeutic potential of human MSC-EVs in mice exposed to high-dose total body irradiation (TBI). Mice were exposed to 0, 700, or 950 cGy TBI and subsequently received daily intravenous MSC-EV injections (1 × 10⁹ particles) for 3 days postirradiation. We evaluated survival rates, peripheral blood recovery, bone marrow engraftment, and bone marrow gene expression profiles at various intervals following treatment. MSC-EV administration significantly enhanced survival, with 70% of treated mice surviving 120 days after 950 cGy TBI exposure, compared with 0% survival in untreated controls by day 30. Although early peripheral blood recovery was not observed within 14 days, MSC-EV treatment facilitated substantial recovery at 3 months postirradiation, with significant increases in red blood cell, platelet, white blood cell, and hemoglobin levels, despite white blood cell and hemoglobin levels remaining slightly below normal. Furthermore, the engraftment capacity of bone marrow stem cells was significantly improved. The changes in hematopoietic-related gene expression presented at 14 days postirradiation returned to normal levels by 120 days in MSC-EV-treated mice. These results highlight the potential of MSC-EVs as a therapeutic strategy for high-dose radiation injuries by promoting hematopoietic recovery and improving survival. Our future research will focus on elucidating the radioprotective mechanisms and investigating their integration with existing therapies.

The microenvironment within lymph nodes plays a pivotal role in the pathogenesis of follicular lymphoma (FL), a malignancy characterized by the accumulation of neoplastic B cells. Here, we report that human FL lymph node mesenchymal stromal cells (FLSCs) display surface protein expression profiles consistent with the standard phenotypic criteria for human mesenchymal stromal/stem cells (MSCs), yet exhibit reduced mesenchymal differentiation capability. FLSCs did not show the typical immunomodulatory protein expression patterns observed in fibroblastic reticular cells, marginal reticular cells, or follicular dendritic cells, as they expressed chemokine (C-X-C motif) ligand 13 and podoplanin but lacked chemokine (C-C motif) ligand 19 and complement receptor 1/2. Functionally, FLSCs exhibited superior FL cell survival-supportive capability in cocultures compared with bone marrow MSCs. This supportive effect was reduced when the cell culture inserts were used. In addition, this supportive capability was accompanied by reduced levels of B-cell-supportive soluble factors such as interleukin-6, regardless of the presence of cell culture inserts. Thus, both cell-cell contact-dependent and -independent mechanisms are involved in this process. Comprehensive transcriptomic analysis revealed that transcription factor paired-like homeodomain 1 (PITX1) is downregulated in FLSCs. Given that PITX1 regulates human telomerase reverse transcriptase (hTERT) transcription, FLSCs exhibited longer telomeres and a higher population-doubling capacity than MSCs. Furthermore, FLSCs expressed elevated podoplanin, whereas MSCs did not. Notably, hTERT-transfected MSCs also showed increased podoplanin expression, suggesting a positive association between hTERT and podoplanin. In summary, our findings indicate that FLSCs deviate from classical MSCs in their differentiation potential and instead exhibit a protumorigenic phenotype. This phenotype supports FL cell survival and is potentially mediated by an aberrant PITX1-hTERT-podoplanin signaling axis. These results highlight the critical role of FLSCs in the FL lymph node microenvironment, with implications for understanding tumor-supportive niches in FL pathogenesis.

Neural organoids derived from human-induced pluripotent stem cells (iPSCs) provide a model to study the earliest stages of human brain development, including neurogenesis, neural differentiation, and synaptogenesis. However, neural organoids lack supportive tissues and some non-neural cell types that are key regulators of brain development. Neural organoids have instead been cocultured with non-neural structures and cell types to promote their maturation and model interactions with neuronal cells. One component of the brain that does not form de novo in neural organoids is the meninges, a trilayered structure that surrounds the central nervous system and secretes key signaling molecules required for mammalian brain development. Most studies of meninges-brain signaling have been performed in mice or using two-dimensional cultures of human cells, which do not accurately recapitulate the architecture and cellular diversity of the tissue. To overcome this, we developed a coculture system of neural organoids generated from human iPSCs fused with fetal leptomeninges (LPM) from mice with fluorescently labeled meninges (Col1a1-GFP), which we call leptomeningeal neural organoid (LMNO) fusions. This proof-of-concept study tests the stability of the different cell types in the LPM (fibroblasts and macrophages) and the fused neural organoid (progenitors and neurons), as well as the interface between the organoid and meningeal tissue. We test the longevity of the fusion pieces after 30 and 60 days in culture, describe best practices for preparing the meninges sample before fusion, and examine the feasibility of single or multiple meninges pieces fused to a single organoid. We discuss potential uses of the current version of the LMNO fusion model and opportunities to improve the system.

The development of acute graft-versus-host disease (GvHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is facilitated by damage-associated molecular patterns (DAMPs) released upon tissue damage due to the conditioning regimen. Heme oxygenase-1 (HO-1) is a stress-inducible enzyme responsible for the breakdown of the DAMP cell-free heme. HO-1 plays a protective role in diseases characterized by systemic inflammation such as sepsis, but its role in the development of acute GvHD remains unclear. Here, we characterized the expression of HO-1 in a small cohort of allo-HSCT recipients with and without acute GvHD. We found HO-1 protein levels in plasma to be elevated in patients just before their acute GvHD diagnosis compared with baseline. Furthermore, HO-1 mRNA expression was increased in patients with acute GvHD at 1 and 3 months after allogeneic HSCT compared with patients without acute GvHD. Finally, induction of HO-1 in a humanized mouse model for acute GvHD led to lower disease scores and a reduction in weight loss. Overall, our data indicate that HO-1 expression is increased in patients with acute GvHD and that HO-1 induction might be able to provide protection against the disease, warranting further research into HO-1 as a target for clinical application.

Orchestrated changes in cell arrangements and cell-to-cell contacts are susceptible to cellular stressors during central nervous system development. Effects of mitochondrial complex I inhibition on cell-to-cell contacts have been studied in vascular and intestinal structures; however, its effects on developing neuronal cells are largely unknown. We investigated the effects of the classical mitochondrial stressor and complex I inhibitor, rotenone, on the architecture of neural rosettes-radially organized neuronal progenitor cells (NPCs)-differentiated from human-induced pluripotent stem cells. We then analyzed the effects of rotenone on the distribution of cell-contact proteins within neural rosettes. Exposure to rotenone for 24 hours led to a dose-dependent irreversible disruption of the neural rosette architecture and relocalization of the cell-contact proteins ZO-1, β-catenin, and N-cadherin from the rosette center to the pericellular region. Though the levels of nestin and SOX2 remained unchanged, NPCs showed decreased levels of the NPC marker PAX6 and exhibited impaired neurogenesis following rotenone exposure. Our study suggests that complex I inhibition leads to a rearrangement of intercellular contacts with disruptive effects on neuronal development.

Japan's regenerative medicine sector has encountered major challenges, underscored by the recent failures of products such as HeartSheet and Collategene. These setbacks expose critical weaknesses in the fast-track approval system, raising concerns about patient safety and the scientific robustness of product evaluations. Despite strong governmental support, addressing these fundamental issues is essential for the future success of regenerative medicine in Japan.

Spiral ganglion neurons (SGNs) are crucial for transferring auditory signals from cochlear sensory hair cells to the brainstem. However, SGNs are usually damaged in sensorineural hearing loss. Embryonic stem cells (ESCs) have been used to regenerate SGNs, but it is obscure whether ESC-derived neurons can fully resemble SGN subtype features. This study aimed to understand the effect of neurotrophins on the generation of SGN-like cells from ESCs and their subsequent subtype specification. This study utilized a stepwise neuronal generation approach to direct DsRed ESCs toward neural progenitors and eventually SGN-like cells. The derived SGN-like cells expressed multiple neuronal markers, including Tuj1, Map2, and NeuN, indicating maturity. Neurotrophins, including brain-derived neurotrophic factor, neutrotrophin-3, and nerve growth factor, seemed to regulate the generation of mature neurons from ESCs. In addition, derived neuron-like cells expressed the otic protein marker Gata3 and glutamatergic marker VGluT1, suggesting that they are SGN-like the glutamatergic cells. Significantly more SGN subtype marker-positive cells, including Pou4f1, calbindin, and calretinin-positive cells, were observed in the neurotrophin treatment groups. Overall, this study indicates the potential of SGN subtype generation from ESCs, which could be significant for cochlear implant therapy or stem cell-based replacement studies.

Direct conversion is an innovative new technology that involves the conversion of somatic cells to target cells without passing through a pluripotent state. Forced expression alone or in combination with transcription factors (TFs), which are critical for the generation of target cells, is important for successful direct conversion. However, most somatic cells are unable to directly convert into target cells even with forced expression. We herein demonstrated that epithelial-mesenchymal transition (EMT) is advantageous for the direct conversion of somatic cells. We previously reported that mouse keratinocytes converted into neural crest cells (NCCs) following the forced expression of the NCC specifier Sox10 in combination with expression of the TFs Snail1, Slug, Twist1, and Tcfap2a (4 TFs). 4 TFs induced EMT in keratinocytes; therefore, EMT was considered to be advantageous for direct conversion. The direct conversion of mouse mammary gland epithelial cells (NMuMG cells) into NCCs was not observed with the forced expression of Sox10, but was detected with the expression of Sox10 following the induction of EMT by 4 TFs. Furthermore, TGF-β1-induced EMT and Sox10 expression directly converted NMuMG cells into NCCs. These results suggest that the induction of EMT in somatic cells is advantageous for direct conversion.

Acute renal ischemia-reperfusion injury (IRI) poses significant challenges in clinical management, necessitating the exploration of novel therapeutic strategies. This study investigates the therapeutic potential and underlying mechanisms of multilineage-differentiating stress-enduring (Muse) cells in alleviating renal IRI. In recent years, stem cell research has advanced significantly, providing promising prospects for clinical treatment. Mesenchymal stromal cells (MSCs), from which Muse cells are derived, are a heterogeneous population of cells that include stem cells with varying degrees of multipotency, committed progenitors, and differentiated cells. Muse cells, a subpopulation of MSCs, were isolated from adipose tissue obtained through liposuction in this study. In vivo studies revealed the effective recruitment of Muse cells to injured kidneys and their ability to ameliorate renal pathological damage and improve renal function in a rat model of acute kidney IRI. Mechanistically, Muse cells modulated the polarization of macrophages toward an anti-inflammatory M2 phenotype, as evidenced by decreased M1/M2 ratios. In vitro experiments further elucidated the interaction between Muse cells and macrophages, demonstrating Muse cell-mediated promotion of M2 polarization. Co-culture with M2 macrophages during reoxygenation phases enhanced the survival of renal tubular epithelial cells following hypoxia-reoxygenation injury, highlighting the therapeutic potential of Muse cells in mitigating renal IRI through modulation of macrophage polarization. These findings provide insights into the therapeutic mechanisms of Muse cells and offer promising avenues for the development of innovative renal injury treatments.

Hypertension, commonly known as high blood pressure, is a significant health issue that increases the risk of cardiovascular diseases, stroke, and renal failure. This condition broadly encompasses both primary and secondary forms. Despite extensive research, the underlying mechanisms of systemic arterial hypertension-particularly primary hypertension, which has no identifiable cause and is affected by genetic and lifestyle agents-remain complex and not fully understood. Recent studies indicate that an imbalance in gut microbiota, referred to as dysbiosis, may promote hypertension, affecting blood pressure regulation through metabolites such as short-chain fatty acids and trimethylamine N-oxide. Current antihypertensive medications face limitations, including resistance and adherence issues, highlighting the need for novel therapeutic approaches. Stem cell therapy, an emerging field in regenerative medicine, shows promise in addressing these challenges. Stem cells, with mesenchymal stem cells being a prime example, have regenerative, anti-inflammatory, and immunomodulatory properties. Emerging research indicates that stem cells can modulate gut microbiota, reduce inflammation, and improve vascular health, potentially aiding in blood pressure management. Research has shown the positive impact of stem cells on gut microbiota in various disorders, suggesting their potential therapeutic role in treating hypertension. This review synthesizes the recent studies on the complex interactions between gut microbiota, stem cells, and systemic arterial hypertension. By offering a thorough analysis of the current literature, it highlights key insights, uncovers critical gaps, and identifies emerging trends that will inform and guide future investigations in this rapidly advancing field.