Strontium (Sr)-based nanofibers have gained great attention in biomedical and tissue engineering applications due to their unique ability to combine nanoscale structural features with the biological activity of Sr ions (Sr2+). Nanofibers offer a versatile platform to harness these properties owing to their high surface area, tunable porosity, and mechanical strength. The incorporation of Sr2+ ions further enhances their bio-functionality and offers a cost-effective alternative to growth factor-based strategies. Sr2+ ions could stimulate the production of growth factors such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), thereby promoting neovascularization, while also enhancing osteogenesis by mimicking calcium's physiological role, inducing mesenchymal stem cell differentiation, and stimulating extracellular matrix mineralization. This review summarizes recent advances in the fabrication techniques such as electrospinning, assisted-electrospinning, and non-electrospinning, including the design, control composition, morphology, and functionality of Sr-based nanofibers. The mechanisms governing Sr2+ ions interactions with cells and tissues are discussed, along with in vitro and in vivo biological outcomes. Our bibliometric analysis shows that Sr-based nanofibers have been most extensively investigated in bone tissue engineering, followed by applications in drug delivery and tumor therapy, with fewer studies exploring skin and cartilage regeneration. This review highlights the advantages and disadvantages of every fabrication strategy, discusses biomedical applications of Sr-based nanofibers, and outlines challenges and future directions for their clinical translation.

Cystinosis is a systemic lysosomal storage disease resulting from mutations in the CTNS gene encoding the lysosomal cystine transporter cystinosin, leading to cystine accumulation in all organs. Despite cystinosin's ubiquitous expression, renal Fanconi syndrome (FS) is the first clinical manifestation of cystinosis, which is not prevented by cystine reduction therapy with cysteamine. Here, we report a novel interaction of cystinosin and sodium/hydrogen (Na+/H+) exchanger proteins in the endosomes of yeast and mammalian cells. NHE3 is a major absorptive sodium transporter at the apical membrane of proximal tubular cells (PTCs). Cystinosin is required for the correct subcellular localization and trafficking of NHE3 and for sodium uptake. Introducing CTNS successfully rescues these defects in CTNS- deficient PTCs, whereas CTNS-LKG, encoding the lysosomal and plasma membrane isoform of cystinosin, did not. NHE3 mislocalization was confirmed in Ctns-/- mice and cystinosis patient kidney. Transplantation of wild-type hematopoietic stem and progenitor cells in Ctns-/- mice restores NHE3 expression at the brush border membrane and improves FS-related phenotypes. This study uncovers an evolutionary conserved novel role of cystinosin in NHE3 trafficking, offering insights into FS pathogenesis and potential new therapeutic avenues.

DNA replication timing (RT) often correlates with transcription during cell fate transitions, yet notable exceptions indicate a complex relationship. Using a reductionist system in mouse embryonic stem cells, we manipulate transcriptional length and strength at a single locus upstream of the silent, late-replicating Pleiotrophin (Ptn) gene. Small reporter genes driven by two of four promoters advance RT, whereas all promoters advance RT when driving the 96-kb endogenous Ptn gene. Inducible transcription of Ptn, but not the reporter, triggers a rapid and reversible RT advance, providing a system to manipulate RT independent of differentiation. Strikingly, deletion of the Ptn promoter and enhancers abolishes transcription yet does not prevent the developmental RT switch to early replication during neural differentiation. These findings, supported by parallel genome-wide analyses during differentiation, demonstrate that transcriptional elongation can causally advance RT in a rate-dependent and context-specific manner, but that transcription is neither necessary nor sufficient for RT advancement. Our results provide a solid empirical base with which to re-evaluate decades of seemingly contradictory literature.

The Drosophila midgut epithelium undergoes nutrient-dependent growth regulated by the InR-Akt-TOR signaling pathway, though the downstream transducers that coordinate this response remain incompletely defined. We demonstrate that hipk is selectively expressed in intestinal stem cells (ISCs) and their immediate progeny, enteroblasts (EBs), the transient precursors to the absorptive enterocytes (ECs) that form the bulk of the gut epithelium. Hipk expression is dynamically regulated by nutritional status and requires active InR-Akt-TOR signaling; notably, ectopic activation of this pathway is sufficient to induce hipk expression even under nutrient-restricted conditions. Through genetic analysis, we show that Hipk promotes ISC proliferation while simultaneously directing lineage specification toward the EB fate, thereby facilitating expansion of the absorptive epithelium in response to nutrient availability. These findings establish Hipk as a critical nutrient-responsive effector that couples insulin signaling to both stem cell division and lineage commitment in the adult intestine.

A reduction in the number of neurons and an increased susceptibility to apoptosis are one of the characteristic features observed in Down syndrome (DS). However, the multifaceted actions of chromosomal aneuploidy hinder the elucidation of the underlying mechanism. Here, using neurons and astrocytes differentiated from patient-derived induced pluripotent stem cells (iPSCs), we aimed to clarify the neuropathology of DS by focusing on aneuploidy-associated stress and the dosage effects of specific genes. Human chromosomal trisomies 13, 18, and 21 exert a stress response on neurons, resulting in the accumulation of protein aggregates. In addition, DYRK1A overdosage in trisomy 21 astrocytes causes intrinsic activation of the NLRP3 inflammasome, which leads to the release of inflammatory cytokines. These dual actions reciprocally interact and enhance neuronal apoptosis in trisomy 21. Notably, correction of DYRK1A copy number successfully rescued apoptotic neural death in combination with a chemical chaperone treatment. Our study provides insights into the neuropathological mechanism of DS and its potential therapeutic strategy.

The SARS-CoV-2 mRNA vaccine provides effective protection against viral infection and severe disease by inducing efficient adaptive immunity. However, vaccine efficacy is decreased against emerging variants, and immune memory is relatively short-lived. Here, we added new T cell epitopes to the RBD (receptor-binding domain) mRNA vaccine and identified a SARS-CoV-2 membrane epitope that significantly improved vaccine-induced immunity and protection in vivo. That new vaccine, designated G1-C, induced 8.2-fold higher levels of RBD-specific antibodies than did RBD and enhanced spike-specific T cell and B cell responses. Remarkably, the G1-C modulated hematopoietic stem cell (HSC) differentiation and increased levels of B and NK cells by regulating multiple signaling pathways in bone marrow potentially via Fos, Klf4, and Klf6 transcription factors. Altogether, these findings identify a new vaccine candidate to control viral infection by affecting the lymphoid-myeloid lineage bias and suggest the potential role of T cell epitopes in vaccine design and development.

Controlled signaling activity is vital for normal tissue homeostasis and oncogenic signaling activation facilitates tumorigenesis. Here, we combine single-cell transcriptomics with in-depth genetic and imaging analysis to investigate the role of the EGFR-Ras and Hedgehog signaling pathways in homeostasis of the Drosophila follicle stem cell lineage. We find that Hedgehog signaling simultaneously promotes an undifferentiated state and induces differentiation via activation of the epithelial-mesenchymal-transition associated transcription factor Zfh1. Overactivation of Hedgehog signaling generates a mixed transcriptional state comparable to partial epithelial-mesenchymal-transition. EGFR-Ras overactivation induces cell cycle defects by activating the transcription factors Pointed and E2f1 and impedes differentiation. Overactivation of both pathways blocks differentiation and induces tumor-like growth where follicle cells exhibit a loss of tissue architecture, sustained proliferation and a reduced lifespan of the host. These findings provide new insight into how signaling pathways converge at the transcriptional level to prevent malignant cell behavior.

Osteosarcoma (OS) remains a challenging malignancy with a high propensity for metastasis and poor survival outcomes. Bone marrow mesenchymal stem cell-derived extracellular vesicles (BMSC-EVs) have emerged as key mediators in the tumor microenvironment, promoting OS progression. This study identifies a novel molecular axis centered on circRNA-0010220 within BMSC-EVs that drives OS aggressiveness. We demonstrate that BMSC-EVs are internalized by OS cells, enhancing their proliferation, migration, and invasion. High-throughput sequencing revealed circRNA-0010220 as the most significantly upregulated circRNA in EV-treated OS cells. Functional studies showed that circRNA-0010220 knockdown in BMSCs attenuated the oncogenic effects of their EVs both in vitro and in vivo. Mechanistically, circRNA-0010220 recruits the histone methyltransferase EZH2 to the CTNNBIP1 promoter, facilitating H3K27me3-mediated epigenetic silencing. The subsequent downregulation of CTNNBIP1 leads to activation of the Wnt/β-catenin signaling pathway. This cascade was consistently observed across gain-of-function and loss-of-function experiments, and pharmacologic inhibition of β-catenin reversed the pro-tumorigenic effects. Our findings elucidate a complete signaling axis from BMSC-EVs to Wnt/β-catenin activation via circRNA-0010220/EZH2/CTNNBIP1, providing new insights into the epigenetic regulation of OS progression and suggesting potential therapeutic targets.

Gastric cancer (GC) remains a significant global health challenge due to the prevalence of multidrug resistance (MDR) that leads to therapy failure. MDR is driven by tumor heterogeneity and the presence of cancer stem cells (CSCs). Drug repurposing represents an innovative therapeutic strategy to overcome MDR. In this view, Salinomycin (Sal) has shown promising anticancer activity and selectivity against CSCs. Since its mechanisms in GC are not fully understood, we investigated its activity in a panel of four GC cell lines: SNU1, NCI-N87, AGS, and KATO-III. Our results demonstrate that Sal induces distinct forms of regulated cell death (RCD) in a cell line-specific manner. Sal treatment led to apoptosis in SNU1 and NCI-N87 cells, while it triggered ferroptosis in AGS and KATO-III cells. Autophagy was a common early event in all cell lines. Western blot analysis confirmed the activation of distinct signaling axes: mTOR/survivin/CASP-3/BAX in apoptotic cells and mTOR/survivin/SLC7A11/GPX4 in ferroptotic cells. Bioinformatics analysis revealed a unique 20-differentially expressed gene signature for ferroptosis-prone GC cells. Notably, Sal significantly reduced the proportion of CD44+ and CD133+ CSCs in the drug-resistant KATO-III and NCI-N87 cell lines. By selectively inducing either apoptosis or ferroptosis, Sal effectively overcomes MDR and targets the CSC population by reducing the capability to form spheroids and colonies. Moreover, our ferroptosis-related gene signature resulted useful to stratify GC patients and was found associated with better outcomes, highlighting the translational potential of Sal treatment. Indeed, it was effective to promote both apoptotic and ferroptotic RCD on patient-derived gastric cancer organoids. Notably, autophagy was a common RCD mechanism also in this preclinical model. Our findings suggest that Sal is a promising candidate for GC treatment, and understanding a tumor's specific molecular susceptibilities could enable the development of personalized therapeutic strategies.

Autosomal dominant polycystic kidney disease is a highly prevalent hereditary renal disorder caused by mutations in either polycystin-1 or polycystin-2. These patients also develop cardiomyopathies. However, the mechanism of how polycystin-2 defects could lead to cardiomyopathies is poorly understood. Moreover, previous studies using animal models cannot fully represent human cardiomyocyte pathophysiology. Human embryonic stem cells were differentiated into cardiomyocytes. These cardiomyocytes were transduced with viral-based polycystin-2-shRNAs, then mixed with an appropriate amount of human fetal fibroblasts, collagen, and Matrigel, and biofabricated into 3D bioengineered ventricular cardiac tissue strips (hvCTS). We used these 3D hvCTS and 2D human embryonic stem cells-derived cardiomyocytes to recapitulate polycystin-2 deficiency-associated cardiac contractile defects and to explore underlying mechanisms. Knockdown of polycystin-2 decreased the contractile force and slowed down the contraction and relaxation velocities in hvCTS, indicative of contractile malfunction. The underlying mechanisms involved an elevated endoplasmic reticulum stress and a decreased activity of sarcoplasmic reticulum Ca2+-ATPases. Alleviation of endoplasmic reticulum stress by small molecular chaperones 4-phenylbutyrate/tauroursodeoxycholic acid or stimulation of sarcoplasmic reticulum Ca2+-ATPase activity by CDN1163 partially rescued the polycystin-2 deficiency-associated contractile dysfunction in hvCTS. This study used 3D hvCTS and 2D human embryonic stem cells-derived cardiomyocytes as novel disease models to recapitulate PKD2 deficiency-associated contractile defects. We found that knockdown of polycystin-2 induces cardiomyopathies via elevating endoplasmic reticulum stress and decreasing sarcoplasmic reticulum Ca2+-ATPase activity. The results provide novel insights about polycystin-2 deficiency-associated cardiomyopathies in polycystic kidney disease patients.

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults, with poor prognosis despite multimodal therapy. Chloride cotransporters NKCC1 and KCC2 are key regulators of intracellular chloride levels and thereby determine whether GABA acts inhibitory or excitatory. In GBM, disrupted chloride homeostasis promotes proliferation, migration, and stem-like properties, but its clinical relevance is not fully understood. We analyzed NKCC1 and KCC2 expression in GBM samples, considering clinical parameters, such as age, gender, and MGMT promoter methylation. Statistical analyses included ROC-based cutoff determination, Kaplan-Meier survival analysis, and subgroup. Immunohistochemistry was performed to identify cell types expressing NKCC1. NKCC1 expression was significantly higher in older patients and emerged as a prognostic marker for recurrence-free survival, with lower levels correlating with delayed recurrence, although overall survival was unaffected. NKCC1 was expressed in stem-like, astrocytic, and neuronal progenitor cells, but not in mature neurons. These findings identify NKCC1 as a regulator of GBM progression and recurrence, linking chloride transporter imbalance to GABAergic signaling. Targeting NKCC1 and restoring chloride homeostasis may provide promising new treatment strategies.

The atrioventricular node (AVN) ensures synchronized heart contractions by establishing the electrical connection between the atria and ventricles. Dysfunction of the pacemaker cells of the AVN leads to atrioventricular block (AV block), a life-threatening condition managed with electronic pacemakers (EPMs). EPMs have drawbacks that could potentially be overcome by a human pluripotent stem cell (hPSC)-derived biological conduction bridge (BioCB). Recent studies demonstrated the differentiation of AVN-like cells from hPSCs, but their conduction properties upon engraftment in vivo remain unexplored. Here, we report the generation of AVN-like pacemaker cells (AVNLPCs) from hPSCs using Wnt and BMP signaling modulation. These AVNLPCs transcriptionally resemble fetal AVN pacemaker cells, exhibit pacemaker action potentials, and display unique AVN-like conduction properties. Notably, when transplanted into the guinea pig heart, AVNLPCs replicate the functional properties of the AVN. Our study highlights the potential of an AVNLPC-based BioCB as a novel cell therapy to improve treatment for patients with AV block.

DNA damage and mutations in hematopoietic stem cells (HSCs) enable clonal hematopoiesis (CH). Such damage occurs across a lifetime, but its origins remain unknown. Here, we demonstrate that endogenous formaldehyde causes HSC attrition and subsequently CH. We generated conditional mouse models lacking formaldehyde detoxification and Fanconi anemia (FA) DNA repair in blood. Formaldehyde protection was crucial for embryonic HSC emergence and throughout life. Despite severe deficiencies in HSCs, these mice produced blood for many months. To determine what enables this, we employed an unbiased method for detecting clones, which exploits somatic variant data. This revealed initial polyclonal hematopoiesis that diminishes to monoclonal hematopoiesis, devoid of known genetic selection. Furthermore, in FA children, we find the same transition to monoclonal hematopoiesis. Therefore, DNA damage-induced attrition down to the last functional cell can be a driving force for CH, representing an alternative route to CH other than purely by fitness-enhancing selection.

Most animals experience irreversibly declining health with advancing age, in part due to limitations in cell turnover and the accumulation of damage. The highly regenerative planarian Schmidtea mediterranea has abundant pluripotent stem cells that drive continuous cell turnover, yet it experiences an age-related loss of fertility, which can be restored through regeneration. We find that the source of planarian age-related infertility lies in the female reproductive system, accompanied by the formation of posterior ectopic ovaries and disrupted accessory reproductive structures, which are restored during regeneration. We further observe that the Notum/Wnt signaling gradient, which determines anterior-posterior polarity in planarians, is shifted posteriorly with age and that manipulating this gradient by RNAi was able to slow down or accelerate reproductive aging. These results indicate that in addition to a healthy stem cell pool, tissue polarity must be maintained to mitigate age-related decline and that resetting positional information could be a promising mechanism to promote tissue rejuvenation.

Mesenchymal stem cells have great therapeutic potential due to their antiinflammatory, anti-apoptotic and pro-angiogenic effects through their secretome. Wharton’s gelatin is one of the best sources of mesenchymal stromal stem cells; their secretome is rich in bioactive molecules with the ability to maintain cellular and tissue homeostasis for the treatment of pathologies such as inflammation, skin wounds, neurodegenerative disorders, and diabetes.

Aging of the male reproductive system is characterized by declining fertility, with epididymal dysfunction being a critical yet poorly understood contributor. Through a multimodal analysis in non-human primates that integrated histology and transcriptomics, we delineated a coherent epididymal aging phenotype encompassing epithelial senescence, chronic inflammation, fibrosis, and functional decline. Single-nucleus transcriptomics revealed principal cells (PCs) as the predominant and most transcriptionally perturbed epithelial cell type. Within PCs, the longevity-associated transcription factor FOXO1 was markedly downregulated with age. Functional studies in human epididymal epithelial cells demonstrated that FOXO1 deficiency drives cellular senescence. Mechanistically, FOXO1 transcriptionally activates LHX1, and this axis is essential for counteracting senescence. Furthermore, intervention with senescence-resistant mesenchymal progenitor cells or their exosomes mitigated epididymal aging phenotypes and restored FOXO1 expression in vivo and in vitro. Our study establishes the FOXO1-LHX1 axis as a key protective pathway against primate epididymal aging, providing mechanistic insights and potential therapeutic targets for preserving male reproductive health.