STEM CELLS最新文献

Neuronal branching, the extension and arborization of neurites, is critical for establishing and maintaining functional neural circuits. Emerging evidence suggests that mitochondria play an important role in regulating this process. In this review, we explore how the use of human induced pluripotent stem cell (iPSC)-derived neuronal models in two dimensions (2D) and three dimensions (3D) could help uncover possible mechanisms linking mitochondrial function and dysfunction to neuronal branching capacity. We highlight examples of iPSC-based models of mitochondrial and neurological diseases where aberrant neurite growth has been observed and discuss the potential therapeutic implications. Additionally, we review current methodologies for assessing neurite outgrowth in 2D and 3D neuronal models, addressing their strengths and limitations. Insights gained from these models emphasize the significance of mitochondrial health in neuronal branching and demonstrate the potential of iPSC-derived neurons and brain organoids for studying disrupted neuronal morphology. Harnessing these human stem cell models to devise phenotypic drug discovery platforms can eventually pave the way for innovative therapeutic interventions, particularly in the context of disorders with poorly understood genetic mechanisms and limited therapeutic options.

Background: Breast cancer is a highly heterogeneous disease with diverse phenotypes. At present, increasing evidence supports the role of ribosomal biogenesis in human diseases and tumorigenesis. PNO1, as a ribosome assembly factor, plays a key role in the biological synthesis of ribosomes and ribosomal protein mutations associated with human diseases and tumor development. This study explored PNO1's role as a prognostic biomarker for breast cancer.

Methods: Clinical samples and online datasets were used to determine PNO1 expression in breast cancers with different molecular phenotypes and clinicopathological subtypes. CCK-8 assays, colony formation assays, wound healing, and transwell assays were performed to investigate tumor cell proliferation, migration, and invasion. Western blot, flow cytometry, and sphere-formation assays were used to assess the effect of PNO1 on breast cancer stemness. RNA-sequencing analysis was also performed to elucidate the underlying mechanism.

Results: Results showed that the expression level of PNO1 was upregulated in breast cancer samples. In addition, high PNO1 expression was positively correlated with poor survival in breast cancer patients with different molecular types. Moreover, PNO1 was associated with breast cancer heterogeneity by promoting its stem-like properties both in vitro and in vivo through the NF-κB signaling pathway, which can be suppressed by JSH-23.

Conclusions: Our study found that PNO1 expression was positively correlated with poor survival in different molecular subtypes of breast cancer and that PNO1 promoted stem-like properties of breast cancer by activating NF-κB activity. Collectively, PNO1 is a potential prognostic biomarker that plays an important role in breast cancer progression.

The role of peroxisomes in hematopoiesis remains poorly understood. The PEX1-Gly844Asp knock-in mouse lacks peroxisome formation and is peroxisome deficient. We observed that peroxisome-deficient animals had up to 50% greater numbers of peripheral lymphocytes, neutrophils, and platelets which contained 2-fold greater reactive oxygen species (ROS, P = .0002). The marrow contained 2-fold greater numbers of cells and colony forming unit (P = .0009 and <.0001, respectively). We found expansion (up to 3-fold) in the hematopoietic stem and progenitor cell (HSPC) compartment compared to that of wild-type (WT) animals demonstrated by: in vivo enumeration of Lin-SCA1+c-KIT+ (LSK) (P < .0001). Importantly through competitive bone marrow transplant experiments (primary and secondary), we show that peroxisome-deficient cells outcompete WT. We further demonstrate that peroxisome-deficient HSPC harbor very high levels of intrinsic ROS which are attenuated after repopulation. Isolation of mesenchymal stem cells (MSC) isolated from peroxisome-deficient mice also showed elevated levels of ROS. Finally, we found elevated levels of stem cell factor (SCF) in the plasma of peroxisome-deficient mice, and peroxisome-deficient MSC expressed 2-fold more SCF compared to WT. Chemical induction of ROS also increased SCF expression by MSC. Lin-SCA1+c-KIT+ expanded 10-fold greater in the absence of SCF on peroxisome-deficient MSC than that on WT MSC. In conclusion, the increase in HSPC numbers is, in part, driven by response to ROS in the microenvironment leading to increased SCF. These data add new insight into the role of peroxisomes in the bone marrow niche.

Background: UC‑MSC‑Exos (umbilical cord mesenchymal stem cell‑derived exosomes) offer a potential therapy for captive giant pandas. This study aimed to clarify their proteomic and miRNA profiles and functions to understand therapeutic mechanisms and optimize their application.

Methods: UC‑MSC‑Exos were isolated from giant panda UC‑MSC culture supernatant by ultracentrifugation. Proteomic and miRNA profiles were identified by mass spectrometry and high‑throughput small RNA sequencing, respectively. Dual‑luciferase gene reporter assays were used to evaluate the impact of miR‑21‑5p on DF proliferation.

Results: Giant panda UC‑MSC‑Exos are rich in proteins and miRNAs. They significantly boosted DF proliferation and migration, mediated by growth factors like PDGF, TGF‑β1, b‑FGF, and miR‑21‑5p. We found that miR‑21‑5p contributes to fibroblast proliferation by targeting the programmed cell death 4 (PDCD4) and reversion inducing cysteine rich protein with Kazal motifs (RECK) genes, attenuating the expression of α‑smooth muscle actin (α‑SMA) induced by TGF‑β1, and impeding the differentiation of fibroblasts into myoblasts.

Conclusions: This study comprehensively reveals the functional properties of giant panda UC‑MSC‑Exos as well as their therapeutic potential in wound healing, providing insights for improving tissue regeneration and health in giant pandas.

Stem cell sources capable of producing appropriate cells for replacement will be necessary for functional repair of the injured brain. Here, we have determined whether transcription factor programming of human embryonic stem (hES) cells can be used to generate layer-specific cortical neurons capable of integrating into the stroke-injured rat cortex. Human embryonic stem cells were programmed via overexpression of neurogenin 2 (NGN2). After 7 days, hES-induced neurons (hES-iNs) were characterized in vitro using immunocytochemistry, RT-qPCR, and whole-cell patch-clamp. Cortical ischemic stroke was induced in rats via distal middle cerebral artery occlusion. Forty-eight hours later, hES-iNs were transplanted into the somatosensory cortex adjacent to the ischemic lesion. Three months thereafter, brains were analyzed for expression of neuronal markers, axonal myelination, and synapse formation using immunohistochemistry and immunoelectron microscopy (iEM). Overexpression of NGN2 in hES cells for 7 days generated excitatory neurons, expressing cortical markers at different stages of maturation. After transplantation, the hES-iNs expressed markers of both immature and mature neurons and of upper and deep cortical layers. The hES-iNs sent widespread projections to both hemispheres, and iEM revealed that they were myelinated by host oligodendrocytes and had formed efferent synaptic connections with host cortical neurons. The hES cells programmed via NGN2 overexpression gave rise to subtypes of cortical neurons, capable of integrating structurally into the injured brain, more rapidly than neurons produced by previous protocols. Functional characterization of the grafted hES-iNs and their impact on the balance between brain excitation and inhibition are now highly warranted. This new stem cell source should be considered when, in the future, the most suitable candidate will be selected for clinical translation.

In steady state, hematopoietic stem cells (HSCs) reside quiescently in their hypoxic niche with minimal mitochondrial activity, maintaining characteristically low levels of reactive oxygen species (ROS) and instead favoring glycolysis to meet their low energy requirements. However, stress, such as acute infection, triggers a state of emergency hematopoiesis during which HSCs expand more rapidly to produce up to 10-fold more downstream differentiated immune cells. To cope with this demand, HSCs increase their energy production by switching from low ATP-yielding glycolysis to high ATP-yielding mitochondrial oxidative phosphorylation. It is this metabolic switch that enables rapid HSC expansion and differentiation into downstream progeny to increase the immune cell pool and effectively clear the infection. This metabolic switch relies on the sufficient availability of healthy mitochondria as well as fuel in the form of free fatty acids to drive the necessary production of cellular components. This concise review aims to focus on how HSCs increase their mitochondrial content and fuel ATP production via fatty acid oxidation and the impact of HSC dysfunction during aging and other metabolic diseases.

Background: The integrity and function of the blood‑brain barrier (BBB) are largely regulated by pericytes. Pericyte deficiency leads to BBB breakdown and neurological dysfunction in major neurological disorders including stroke and Alzheimer's disease (AD). Transplantation of pericytes derived from induced pluripotent stem cells (iPSC‑PC) has been shown to restore the BBB and improve functional recovery in mouse models of stroke and pericyte deficiency. However, the molecular profile and functional properties of iPSC‑PC under hypoxic conditions, similar to those found in ischemic and neurodegenerative diseases remain largely unexplored.

Methods: We examined iPSC‑PC under hypoxia to assess molecular marker expression, proliferation, ability to home to brain vessels, and uptake of amyloid beta (Aβ).

Results: iPSC‑PC under severe hypoxia retain essential functional properties, including key molecular markers, proliferation rates, and the ability to migrate to host brain vessels via function‑associated PDGFRB‑PDGF‑BB signaling. Additionally, we show that iPSC‑PC exhibit similar clearance of Aβ neurotoxins from AD mouse brain sections under both normoxic and hypoxic conditions.

Conclusions: These findings suggest that iPSC‑PC functions are largely resilient to hypoxia, highlighting their potential as a promising cell source for treating ischemic and neurodegenerative disorders.

One of the most important properties of human embryonic stem cells (hESCs) is their ability to exist in primed and naive pluripotent states. Our previous meta-analysis indicated the existence of heterogeneous pluripotent states derived from diverse naive protocols. In this study, we characterized a commercial, RSeT-based pluripotent state under various growth conditions. Notably, RSeT hESCs can circumvent the hypoxic growth conditions required by naive hESCs, although some RSeT cells (eg, H1 cells) exhibit much lower single-cell plating efficiency and display altered or significantly retarded cell growth under both normoxia and hypoxia. Importantly, RSeT hPSCs lack many transcriptomic hallmarks of naive and formative pluripotency (the phase between naive and primed states). Integrative transcriptome analysis suggests that our primed and RSeT hESCs are similar to the early stage of post-implantation embryos, in line with previously reported primary hESCs and early hESC cultures. Moreover, RSeT hESCs do not express naive surface markers such as SUSD2 and CD75 at significant levels. At the biochemical level, RSeT hESCs show differential dependence on FGF2 and co-independency on both Janus kinase (JAK) and TGFβ signaling in a cell line-specific manner. Thus, RSeT hESCs represent a previously unrecognized pluripotent state downstream of naive pluripotency. Our data suggest that human naive pluripotent potentials may be restricted in RSeT medium, which sustains FGF2 activity. Hence, this study provides new insights into pluripotent state transitions in vitro.