STEM CELLS最新文献

Stem cell-derived retinal organoids (ROs) have been investigated for applications in regenerative medicine, retinal disease models, and compound safety evaluation. Although the development of 3D organoids has provided novel opportunities for innovation, some unresolved limitations continue to exist in organoid research. The passive diffusion of oxygen and nutrients limits the growth and functional gain of organoids. Vascularization may circumvent these problems because it allows oxygen and nutrients to enter the organoid core. In the present study, ROs and vascular organoids (VOs) were generated from healthy human induced pluripotent stem cells. We attempted to create vascular-like structures in ROs by co-culturing them with VO-derived vascular endothelial cells/pericytes. Our vascularized retinal organoids (vROs) contained type IV collagen- and CD31-positive vascular-like structures. The expression of the mature neuronal marker SMI-32 and SNCG was markedly higher in the vROs than in the ROs. When vROs were cultured under conditions that mimicked diabetes, their size and the number of retinal ganglion cells were significantly decreased. In conclusion, the co-culture of ROs with VO-derived cells enabled the production of ROs with vascular-like structures, and the vROs responded to severe diabetic retinopathy conditions. In summary, our findings underscore the potential of vROs as invaluable tools for elucidating disease mechanisms and screening therapeutic interventions for retinal vascular disorders, thereby paving the way for personalized medicine approaches in ophthalmology.

Synovial joints, such as knee, temporomandibular, and spinal joints, play a key role in human movement and postural maintenance. Biological research has focused on understanding their developmental process and disease mechanisms. In recent years, the rapid development of single-cell transcriptome sequencing has provided a powerful tool for revealing the mysteries of synovial joints. Single-cell transcriptome sequencing can accurately capture the gene expression profile of each cell, thereby revealing the heterogeneity and interactions of different cell types in synovial joints. During joint development, this technique contributes to elucidating the molecular mechanisms of joint formation, cartilage differentiation, and synovial tissue construction. In terms of joint disease research, single-cell sequencing technology has been applied to the molecular pathology studies of various joint diseases such as osteoarthritis, rheumatoid arthritis, and intervertebral disk degeneration, providing new perspectives and strategies for early diagnosis, accurate treatment, and prognosis assessment of diseases.

Over the last two decades, research has increasingly focused on Cancer Stem Cells (CSCs), considered responsible for tumor formation, resistance to therapies, and relapse. The traditional "static" CSC model used to describe tumor heterogeneity has been challenged by the evidence of CSC dynamic nature and plasticity. A comprehensive understanding of the mechanisms underlying this plasticity, and the capacity to unambiguously identify cancer markers to precisely target CSCs are crucial aspects for advancing cancer research and introducing more effective treatment strategies. In this context, Raman spectroscopy (RS) and specific Raman schemes, including CARS, SRS, SERS, have emerged as innovative tools for molecular analyses both in vitro and in vivo. In fact, these techniques have demonstrated considerable potential in the field of cancer detection, as well as in intraoperative settings, thanks to their label-free nature and minimal invasiveness. However, the RS integration in pre-clinical and clinical applications, particularly in the CSC field, remains limited. This review provides a concise overview of the historical development of RS and its advantages. Then, after introducing the CSC features and the challenges in targeting them with traditional methods, we review and discuss the current literature about the application of RS for revealing and characterizing CSCs and their inherent plasticity, including a brief paragraph about the integration of artificial intelligence with RS. By providing the possibility to better characterize the cellular diversity in their microenvironment, RS could revolutionize current diagnostic and therapeutic approaches, enabling early identification of CSCs and facilitating the development of personalized treatment strategies.

Extracellular microvesicles (ExMVs) were one of the first communication platforms between cells that emerged early in evolution. Evidence indicates that all types of cells secrete these small circular structures surrounded by a lipid membrane that plays an important role in cellular physiology and some pathological processes. ExMVs interact with target cells and may stimulate them by ligands expressed on their surface and/or transfer to the target cells their cargo comprising various RNA species, proteins, bioactive lipids, and signaling nucleotides. These small vesicles can also hijack some organelles from the cells and, in particular, transfer mitochondria, which are currently the focus of scientific interest for their potential application in clinical settings. Different mechanisms exist for transferring mitochondria between cells, including their encapsulation in ExMVs or their uptake in a "naked" form. It has also been demonstrated that mitochondria transfer may involve direct cell-cell connections by signaling nanotubules. In addition, evidence accumulated that ExMVs could be enriched for regulatory molecules, including some miRNA species and proteins that regulate the function of mitochondria in the target cells. Recently, a new beneficial effect of mitochondrial transfer has been reported based on inducing the mitophagy process, removing damaged mitochondria in the recipient cells to improve their energetic state. Based on this novel role of ExMVs in powering the energetic state of target cells, we present a current point of view on this topic and review some selected most recent discoveries and recently published most relevant papers.

There is increasing interest in use of marsupial models in research, for use in next-generation conservation by improving fitness through genetic modification, and in de-extinction efforts. Specifically this includes dasyurid marsupials such as the Thylacine, Tasmanian devil, quolls and the small rodent-like dunnarts. Technologies for generating genetically modified Australian marsupials remains to be established. Given the need to advance research in this space, the fat-tailed dunnart (Sminthopsis crassicaudata) is being established as a model for marsupial spermatogonial stem cell isolation, modification and testicular transplantation. This species is small (60-90mm body size), polyovulatory (8-12 pups per birth), and can breed in standard rodent facilities when housed in a 12:12 light cycle. To develop the fat tailed dunnart as a model for next-generation marsupial conservation, this study aimed to enrich dunnart spermatogonial stem cells from whole testis digestions using a fluorescent dye technology and fluorescence-activated cell sorting. This approach is not dependent on antibodies or genetic reporter animals that are limiting factors when performing cell sorting on species separated from human and mouse by large evolutionary timescales. This study also assessed development of spermatogonia and spermatogenesis in the fat-tailed dunnart, by making the first definition of the cycle of the seminiferous epithelium in any dasyurid. Overall, this is the first detailed study to assess the cycle of dasyurid spermatogenesis and provides a valuable method to enrich marsupial spermatogonial stem cells for cellular, functional and molecular analysis.

In our aging society, the degeneration of the musculoskeletal system and adjacent tissues is a growing orthopedic concern. As bones age, they become more fragile, increasing the risk of fractures and injuries. Furthermore, tissues like cartilage accumulate damage, leading to widespread joint issues. Compounding this, the regenerative capacity of these tissues declines with age, exacerbating the consequences of fractures and cartilage deterioration. With rising demand for fracture and cartilage repair, bone-derived stem cells have attracted significant research interest. However, the therapeutic use of stem cells has produced inconsistent results, largely due to ongoing debates and uncertainties regarding the precise identity of the stem cells responsible for musculoskeletal growth, maintenance and repair. This review focuses on the potential to leverage endogenous skeletal stem cells (SSCs)-a well-defined population of stem cells with specific markers, reliable isolation techniques, and functional properties-in bone repair and cartilage regeneration. Understanding SSC behavior in response to injury, including their activation to a functional state, could provide insights into improving treatment outcomes. Techniques like microfracture surgery, which aim to stimulate SSC activity for cartilage repair, are of particular interest. Here, we explore the latest advances in how such interventions may modulate SSC function to enhance bone healing and cartilage regeneration.

The miR-290 and miR-302 clusters of microRNAs are highly expressed in naïve and primed pluripotent stem cells, respectively. Ectopic expression of the embryonic stem cell (ESC)-specific cell cycle regulating family of microRNAs arising from these two clusters dramatically enhances the reprogramming of both mouse and human somatic cells to induced pluripotency. Here, we used genetic knockouts to dissect the requirement for the miR-290 and miR-302 clusters during the reprogramming of mouse fibroblasts into induced pluripotent stem cells (iPSCs) with retrovirally introduced Oct4, Sox2, and Klf4. Knockout of either cluster alone did not negatively impact the efficiency of reprogramming. Resulting cells appeared identical to their ESC microRNA cluster knockout counterparts. In contrast, the combined loss of both clusters blocked the formation of iPSCs. While rare double knockout clones could be isolated, they showed a dramatically reduced proliferation rate, a persistent inability to fully silence the exogenously introduced pluripotency factors, and a transcriptome distinct from individual miR-290 or miR-302 mutant ESC and iPSCs. Taken together, our data show that miR-290 and miR-302 are essential yet interchangeable in reprogramming to the induced pluripotent state.

Exosomes in the hippocampal dentate gyrus are essential for modulating the cell signaling and controlling the neural differentiation of hippocampal neural stem cells (NSCs), which may determine the level of hippocampal adult neurogenesis. In the present study, we found that exosomes secreted by immature neurons may promote the neuronal differentiation of mouse NSCs in vitro. By miRNA sequencing, we discovered that miR-7a-5p was significantly lower in exosomes from differentiated immature neurons than those from undifferentiated NSCs. By modulating the level of miR-7a-5p, the mimic and inhibitor of miR-7a-5p could either inhibit or promote the neuronal differentiation of NSCs, respectively. Moreover, we confirmed that miR-7a-5p affected neurogenesis by directly targeting Tcf12, a transcription factor responsible for the differentiation of NSCs. The siRNA of Tcf12 inhibited neuronal differentiation of NSCs, while overexpression of Tcf12 promoted NSC differentiation. Thus, we conclude that the miR-7a-5p content in neural exosomes is essential to the fate determination of adult hippocampal neurogenesis and that miR-7a-5p directly targets Tcf12 to regulate adult hippocampal neurogenesis.

In the central nervous system, cell-to-cell interaction is essential for brain plassticity and repair, and its alteration is critically involved in the development of neurodegenerative diseases. Neural stem cells are a plentiful source of biological signals promoting neuroplasticity and the maintenance of cognitive functions. Extracellular vesicles (EVs) represent an additional strategy for cells to release signals in the surrounding cellular environment or to exchange information among both neighboring and distant cells. In the last years, rising attention has been devoted to the ability of stem cell (SC)-derived EVs to counteract inflammatory and degenerative brain disorders taking advantage of their immunomodulatory capacities and regenerative potential. Here, we review the role of adult neurogenesis impairment in the cognitive decline associated with neurodegenerative diseases and describe the beneficial effects of SC-derived EVs on brain plasticity and repair also discussing the advantages of SC-derived EV administration vs SC transplantation in the treatment of neurodegenerative disorders.

The role of Notch signaling in direct neuronal reprogramming remains unknown despite its importance to brain development in vivo. Here, we use microRNA-induced neurons that are directly reprogrammed from human fibroblasts to determine how Notch signaling contributes to neuronal identity. We found that Notch inhibition during the first week of reprogramming was both necessary and sufficient to enhance neurite outgrowth at a later timepoint, indicating an important role in the erasure of the original cell identity. Accordingly, transcriptomic analysis showed that the effect of Notch inhibition was likely due to improvements in fibroblast fate erasure and silencing of non-neuronal genes. To this effect, we identify MYLIP, whose downregulation in response to Notch inhibition significantly promoted neurite outgrowth. Moreover, Notch inhibition resulted in cells with neuronal transcriptome signatures defined by expressing long genes at a faster rate than the control, demonstrating the effect of accelerated fate erasure on neuronal fate acquisition. Our results demonstrate the antagonistic role of Notch signaling to the pro-neuronal microRNAs 9 and 124 and the benefits of its inhibition to the acquisition of neuronal morphology.