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BACKGROUND: The discovery of induced pluripotent stem cells revolutionized regenerative medicine,providing a source for generating induced pluripotent stem cell-derived mesenchymal stem cells (iMSCs). AIM: To evaluate and compare five iMSC differentiation protocols,assessing their efficiency,phenotypic characteristics,and functional properties relative to primary mesenchymal stem cells (MSCs). METHODS: Five iMSC differentiation protocols were assessed: SB431542-based differentiation (iMSC1,iMSC3),an iMatrix-free method (iMSC2),growth factor supplementation (iMSC4),and embryoid body formation with retinoic acid (EB-iMSC). iMSC identity was confirmed according to the International Society for Cell & Gene Therapy 2006 criteria,requiring expression of surface markers (CD105,CD73,CD90) and absence of pluripotency markers. Functional assays were conducted to evaluate differentiation potential (osteogenic and adipogenic),proliferation,mitochondrial function,reactive oxygen species,senescence,and migration. RESULTS: All iMSC types expressed MSC markers and lacked pluripotency markers. EB-iMSC and iMSC2 showed enhanced osteogenesis (runt-related transcription factor 2; P ≤ 0.01 and P ≤ 0.0001,respectively),while adipogenic potential was reduced in iMSC2 (Adipsin; P ≤ 0.01) and EB-iMSC (Adipsin and peroxisome proliferator-activated receptor gamma; P ≤ 0.0001 and P ≤ 0.01,respectively). Proliferation was comparable or superior to bone marrow MSCs,except in iMSC1,with iMSC4 showing the highest rate (MTT assay; P values ranged from 0.01 to 0.001). Despite reduced mitochondrial health in iMSC3 and iMSC4 (P ≤ 0.001),reactive oxygen species levels were lower in all iMSCs (P values ranged from 0.001 to 0.0001),and senescence was significantly reduced in all iMSCs with the exception of iMSC1 (P values ranged from 0.01 to 0.0001). Migration was most reduced in iMSC4 (P ≤ 0.001 at 24 hours and P ≤ 0.0001 at 48 hours). CONCLUSION: While all protocols generated functional iMSCs,variations in differentiation,proliferation,and function emphasize the impact of protocol selection. These findings contribute to optimizing iMSC generation for research and clinical applications. View Publication

Background: The pathology of Alzheimer’s Disease (AD) is characterized by aggregates of amyloid beta (Aβ) peptides and neurofibrillary tau tangles. Increased blood-brain barrier (BBB) permeability and reduced Aβ clearance,which signal neurovascular dysfunction,have also been proposed as early markers of AD. Despite intense scrutiny,the mechanisms of AD remain elusive and novel treatments that address core symptoms of dementia are limited. New alternative methods (NAMs) aim to develop in-vitro translational models that recapitulate human pathology more accurately than previous models and could contribute to the development of new therapies. Methods: Here,we developed a NAM model of the cortical neurovascular unit (NVU) using brain cells derived from human induced pluripotent stem cells (hiPSCs) from a patient with AD and a healthy individual. Differentiated neurons,astrocytes,pericytes,microglia,and brain-like microvascular endothelial cells were cultured in a microphysiological system to create a brain-chip model to evaluate NVU-related endpoints. Results: Compared to control,AD brain-chips had reduced claudin-5 and ZO-1 expression and increased paracellular permeability. AD brain-chips also had decreased activity of the efflux transporter P-glycoprotein (P-gp),but its expression was unchanged. In AD brain-chips,levels of Aβ42,total tau,and p-tau 181 were decreased in protein lysates from the brain channel,while levels of total tau and p-tau 181 were increased in protein lysates from the vascular channel. Finally,AD brain-chips had increased levels of the proinflammatory markers IL-6 and MCP-1 in effluent from both brain and vascular channels. Conclusion: In this brain-chip model,we showed Aβ-independent NVU dysfunction that was related to neuroinflammation and vascular tau accumulation. This study demonstrates the utility of the brain-chip model to evaluate changes in NVU functions induced by AD-like pathology and highlights donor-specific responses associated with the use of hiPSC-derived models. View Publication

Ischemia-reperfusion injury (IRI) represents a major challenge in liver transplantation,driving acute dysfunction and contributing to long-term allograft rejection. This process triggers a robust inflammatory response,leading to hepatocyte damage,senescence,and impaired liver regeneration. While the underlying mechanisms remain incompletely understood,increasing evidence highlights macrophage-derived signaling as a pivotal driver of hepatocyte fate during IRI. Here,we identify iRhom2 as a key regulator of immune-mediated liver injury,orchestrating macrophage-driven inflammation and hepatocyte senescence. iRhom2 is known to modulate the secretion of multiple cytokines by macrophages,yet its specific contribution to IRI-driven hepatocyte senescence has not been fully elucidated. We reveal a significant upregulation of iRhom2 in IRI+ reperfused allografts,particularly in Kupffer cells and monocyte-derived macrophages. Functional characterization in iRhom2-deficient macrophages revealed reduced ER stress,preserved mitochondrial function,and attenuated apoptosis,indicating a protective role against IRI-induced cellular damage. Proteomic profiling further uncovers iRhom2-dependent secretion of inflammatory mediators,with HMGB1 emerging as a critical damage-associated molecular pattern (DAMP) molecule in this context. Notably,HMGB1 release occurs independently of TACE catalytic activity,suggesting an alternative unexplored regulatory mechanism. Furthermore,co-culture experiments confirm that macrophage-derived HMGB1 directly induces senescence of human induced pluripotent stem cell-derived hepatocytes (hiPSC-Heps) under in vitro IRI condition,driving the up-regulation of key senescence markers and disrupting cell cycle dynamics. Strikingly,HMGB1 neutralization enhances hepatocyte viability and mitigates senescence,underscoring its pathogenic role. Additionally,HMGB1 knockdown in macrophages protects hepatocytes,though p21 expression remains unaffected,hinting at additional senescence pathways. Our findings establish iRhom2 as a central orchestrator of macrophage-driven hepatocyte dysfunction in IRI and suggest that targeting the iRhom2-HMGB1 axis could represent a promising therapeutic strategy to improve post-transplant liver recovery and long-term graft survival. View Publication

Multiple myeloma (MM) is the second most common hematological malignancy,characterized by a clonal expansion of malignant plasma cells in bone marrow. Monoclonal gammopathy of undetermined significance (MGUS) is the premalignant condition of MM. The tumor microenvironment is thought to influence the progression from premalignant conditions. Myeloid‐derived suppressor cells (MDSCs) are a heterogenous group of different cellular subsets with myeloid origin,characterized by their ability to inhibit T‐cell responses. MDSC are thought to play an important immunoregulatory role in different diseases,and in many cancers their levels seem to correlate with a poor prognosis. There are three different subsets,the neutrophil‐like polymorphonuclear (PMN)‐MDSC,the monocyte‐like (M)‐MDSC,and the immature early (e)MDSC. In this study,we investigate the levels and functions of all MDSC subsets in the bone marrow of both MGUS and MM patients and compare it to blood MDSC. We found that MDSC levels are not increased in neither the blood nor bone marrow of MGUS or MM patients,and they lack strong T‐cell suppressive abilities. Blood PMN‐MDSC seems to have a small inhibitory effect,but mature neutrophils were more suppressive. Interestingly,eMDSC levels were decreased in the blood of MM patients. Our data indicate that MDSC are not key players in the pathogenesis of MM,but that mature neutrophils may be more important as they have a stronger immunoregulatory effect. View Publication

The immunoregulatory effects of probiotics have been widely studied,particularly in maintaining immune balance. Conventional in vitro functional screening of probiotics relies on fresh donor-derived primary immune cells,which often exhibit significant inter-individual and temporal variability,limiting reproducibility and interpretation. As an alternative,human-induced pluripotent stem cell (iPSC)-derived dendritic cells were co-cultured with five probiotic strains in the current study to evaluate their immunomodulatory interactions. To assess whether cytokines produced by probiotic-stimulated dendritic cells can influence T cell differentiation,human CD4+ T cells were exposed to the conditioned medium derived from co-cultures. Enzyme-linked immunosorbent assay results demonstrated that iPSC-derived dendritic cells secreted cytokines at distinct concentrations in response to different probiotic strains,suggesting that these cells can distinguish between different microbial stimuli,and supporting their use in functional probiotic screening. Among the five strains tested,Lactiplantibacillus plantarum LPA-56,Limosilactobacillus reuteri RU-23,and Lactobacillus fermentum Fem-99 induced cytokine production levels that promoted the differentiation of the human CD4+ T cells into regulatory T cells. These findings demonstrate that iPSC-derived dendritic cells have immunomodulatory potential,are reliable for in vitro screening of probiotics,and offer a promising strategy for selecting potent immunoregulatory probiotic candidates. View Publication

Interleukin-17 (IL-17) plays a central role in the pathogenesis of various autoimmune diseases. Soluble CD14 (sCD14),a marker of innate immune activation,is elevated in several inflammatory conditions. However,its influence on IL-17 production and the differentiation of Th17 cells remains poorly understood. We found that sCD14 enhances Th17-associated cytokine production and up-regulates critical transcription factors such as STAT3 and RORC. Notably,sCD14's effect on Th17 polarization was mediated indirectly through autologous sCD14-treated peripheral blood mononuclear cell (PBMC) supernatant (sCD14-PBMC-Sup). Additionally,we identified a distinct cytokine profile enriched for pro-inflammatory cytokines and chemokines in sCD14-treated T cells,further reinforcing the Th17-promoting role of sCD14. Interestingly,gamma-aminobutyric acid (GABA),a metabolite elevated in sCD14-treated monocytes,was identified as a potential contributor to Th17 polarization. GABA supplementation in T-cell cultures enhanced IL-17A secretion,indicating its role as a signaling molecule in T-cell differentiation. Our findings also revealed the expansion of innate lymphoid cell (ILC)2/3-like cells in T-cell cultures exposed to sCD14-PBMC-Sup and GABA,highlighting the potential role of monocytes in Th17-mediated immunity. Furthermore,while sCD14 promoted Th17 polarization,it simultaneously impaired T-cell activation and proliferation,suggesting an immunosuppressive effect mediated by soluble factors released from monocytes. These results underscore the dual role of sCD14 in modulating T-cell responses,promoting Th17 differentiation while suppressing T-cell effector functions. This study identifies a previously unrecognized role for sCD14 in promoting Th17 induction,highlighting its contribution to immune regulation and its potential as a therapeutic target in Th17-driven autoimmune conditions. View Publication

Cis-regulatory elements (CREs) are noncoding DNA regions regulating cell-type-specific gene expression programs by interacting with distal gene promoters. Here,we aim to decode the function and spatial organization of CRE-promoter interactions in human cardiomyocytes. We analyzed the epigenome and chromatin interactions of human male atrial,ventricular,and failing cardiomyocytes. Atrial and ventricular cardiomyocytes harbored chamber-specific CRE-promoter interactions modulating gene expression as confirmed by functional epigenetic silencing. These CRE-promoter interactions explain the distinct contribution of non-coding genetic variants to atrial and ventricular diseases,such as dilated cardiomyopathy and arrhythmias. We dissected the prototypic KCNJ2 locus,encoding a potassium channel associated with ventricular arrhythmia susceptibility. Functional epigenetic silencing confirmed that CREs,harboring QT-duration-associated genetic risk factors,modulate KCNJ2 gene expression levels,alter KCNJ2-dependent channel currents,and affect cardiomyocyte repolarization. The presented human CM-specific chromatin interaction analysis provides key insights into regulatory mechanisms and aids in interpreting genetic risk factors. Here the authors functionally test and resolve the spatial genome organization of cis-regulatory elements and genetic variants in atrial,ventricular,and failing human cardiomyocytes and linked them to heart disease traits,including QT syndrome. View Publication

Expansion microscopy (ExM) has enabled nanoscale imaging of tissues by physically enlarging biological samples in a swellable hydrogel. However,the increased sample size and water-based environment pose challenges for deep imaging using conventional inverted confocal microscopes,particularly due to the limited working distance of high-numerical-aperture (NA) water immersion objectives. Here,we introduce a practical imaging alternative that utilizes an inverted water-dipping objective and a refractive-index-matched optical path using fluorinated ethylene propylene (FEP) film. Through point spread function (PSF) measurements and simulations,we show that the FEP film introduces predominantly defocus-like wavefront profiles characteristic of high NA systems,which result in an easily correctable axial shift of the focal plane. To ensure stable immersion and refractive index continuity,we use an arrangement relying on an FEP film,Immersol W,water and a FEP-based imaging dish. This configuration achieves sub-micron lateral and axial resolution,supports large tile-scan acquisitions,and maintains image quality across depths exceeding 800 µm. We validate the system by imaging 4×-expanded U2OS cells and human cerebral organoids. Our approach provides a low-cost,plug-and-play solution for high-resolution volumetric imaging of expanded samples using standard inverted microscopes. View Publication