Astrocyte-like subpopulation of NG2 glia in the adult mouse cortex exhibits characteristics of neural progenitor cells.

Glial cells expressing neuron-glial antigen 2 (NG2), also known as oligodendrocyte progenitor cells (OPCs), play a critical role in maintaining brain health. However, their ability to differentiate after ischemic injury is poorly understood. The aim of this study was to investigate the properties and functions of NG2 glia in the ischemic brain. Using transgenic mice, we selectively labeled NG2-expressing cells and their progeny in both healthy brain and after focal cerebral ischemia (FCI). Using single-cell RNA sequencing, we classified the labeled glial cells into five distinct subpopulations based on their gene expression patterns. Additionally, we examined the membrane properties of these cells using the patch-clamp technique. Of the identified subpopulations, three were identified as OPCs, whereas the fourth subpopulation had characteristics indicative of cells likely to develop into oligodendrocytes. The fifth subpopulation of NG2 glia showed astrocytic markers and had similarities to neural progenitor cells. Interestingly, this subpopulation was present in both healthy and post-ischemic tissue; however, its gene expression profile changed after ischemia, with increased numbers of genes related to neurogenesis. Immunohistochemical analysis confirmed the temporal expression of neurogenic genes and showed an increased presence of NG2 cells positive for Purkinje cell protein-4 at the periphery of the ischemic lesion 12 days after FCI, as well as NeuN-positive NG2 cells 28 and 60 days after injury. These results suggest the potential development of neuron-like cells arising from NG2 glia in the ischemic tissue. Our study provides insights into the plasticity of NG2 glia and their capacity for neurogenesis after stroke.

Visual stimulation and brain-derived neurotrophic factor (BDNF) have protective effects in experimental autoimmune uveoretinitis.

AIMS: To investigate the therapeutic potential of visual stimulation (VS) and BDNF in murine experimental autoimmune uveoretinitis (EAU). MAIN METHODS: Mice were immunized by subcutaneous injection of interphotoreceptor retinoid-binding protein in Freund's complete adjuvant and intravenous injection of pertussis toxin, and were then exposed to high-contrast VS 12 h/day (days 1-14 post-immunization). EAU severity was assessed by examining clinical score, visual acuity, inflammatory markers, and immune cells in the retina. The transcriptome of activated retinal cells was determined by RNA-seq using RNA immunoprecipitated in complex with phosphorylated ribosomal protein S6. The retinal levels of protein products of relevant upregulated genes were quantified. The effect of BDNF on EAU was tested in unstimulated mice by its daily topical ocular administration (days 8-14 post-immunization). KEY FINDINGS: VS attenuated EAU development and decreased the expression of pro-inflammatory cytokines/chemokines and numbers of immune cells in the retina (n = 10-20 eyes/group for each analysis). In activated retinal cells of control mice (n = 30 eyes/group), VS upregulated genes encoding immunomodulatory neuropeptides, of which BDNF and vasoactive intestinal peptide (VIP) also showed increased mRNA and protein levels in the retina of VS-treated EAU mice (n = 6-10 eyes/group for each analysis). In unstimulated EAU mice, BDNF treatment mimicked the protective effects of VS by modulating the inflammatory and stem cell properties of Müller cells (n = 5 eyes/group for each analysis). SIGNIFICANCE: VS effectively suppresses EAU, at least through enhancing retinal levels of anti-inflammatory and neuroprotective factors, VIP and BDNF. Our findings also suggest BDNF as a promising therapeutic agent for uveitis treatment.

Highly variable biological effects of statins on cancer, non-cancer, and stem cells in vitro.

Statins, the drugs used for the treatment of hypercholesterolemia, have come into the spotlight not only as chemoadjuvants, but also as potential stem cell modulators in the context of regenerative therapy. In our study, we compared the in vitro effects of all clinically used statins on the viability of human pancreatic cancer (MiaPaCa-2) cells, non-cancerous human embryonic kidney (HEK 293) cells and adipose-derived mesenchymal stem cells (ADMSC). Additionally, the effect of statins on viability of MiaPaCa-2 and ADMSC cells spheroids was tested. Furthermore, we performed a microarray analysis on ADMSCs treated with individual statins (12 µM) and compared the importance of the effects of statins on gene expression between stem cells and pancreatic cancer cells. Concentrations of statins that significantly affected cancer cells viability (< 40 µM) did not affect stem cells viability after 24 h. Moreover, statins that didn´t affect viability of cancer cells grown in a monolayer, induce the disintegration of cancer cell spheroids. The effect of statins on gene expression was significantly less pronounced in stem cells compared to pancreatic cancer cells. In conclusion, the low efficacy of statins on non-tumor and stem cells at concentrations sufficient for cancer cells growth inhibition, support their applicability in chemoadjuvant tumor therapy.

The fate of secretory cells during intestinal homeostasis, regeneration, and tumor formation is regulated by Tcf4.

The single-layer epithelium of the gastrointestinal tract is a dynamically renewing tissue that ensures nutrient absorption, secretory and barrier functions and is involved in immune responses. The basis for this homeostatic renewal is the Wnt signaling pathway. Blocking this pathway can lead to epithelial damage, while its abnormal activation can result in the development of intestinal tumors. In this study, we investigated the dynamics of intestinal epithelial cells and tumorigenesis using a conditional mouse model. Using single-cell and bulk RNA sequencing and histological analysis, we elucidated the cellular responses following the loss of specific cell types. We focused on the fate of cells in the lower parts of the intestinal crypts and the development of colon adenomas. By partially inactivating the transcription factor Tcf4, a key effector of the Wnt signaling pathway, we analyzed the regeneration of isolated hyperproliferative foci (crypts). Our results suggest that the damaged epithelium is not restored by a specific regeneration program associated with oncofetal gene production, but rather by a standard homeostatic renewal pathway. Moreover, disruption of Tcf4 in secretory progenitors resulted in a significant shift in the cell lineage from Paneth cells to goblet cells, characterized by morphological changes and loss of Paneth cell-specific genes. We also found that hyperactivation of the Wnt signaling pathway in colonic adenomas correlated with the upregulation of genes typical of Paneth cells in the intestine, followed by the emergence of secretory tumor cells producing the Wnt3 ligand. The absence of Tcf4 led to a phenotypic shift of the tumor cells towards goblet cells. Our study presents a new model of epithelial regeneration based on the genetically driven partial elimination of intestinal crypts. We highlight the critical role of Tcf4 in the control of cell lineage decisions in the intestinal epithelium and colon tumors.