In this issue, Apaydin and Sadhnani et al. report in situ genome editing of human skin to correct a common disease-causing mutation underlying autosomal recessive congenital ichthyosis (ARCI). They combine a base editor,...In this issue, Apaydin and Sadhnani et al. report in situ genome editing of human skin to correct a common disease-causing mutation underlying autosomal recessive congenital ichthyosis (ARCI). They combine a base editor, transient barrier modulation, and topical mRNA-lipid nanoparticle administration to restore clinically meaningful levels of transglutaminase 1 activity.
Midena et al. employ a nanoengineered 3D "nichoid" substrate that mechanically supports CD34 hematopoietic stem and progenitor cells (HSPCs) during ex vivo manipulation, reducing culture-associated stress and improving e...Midena et al. employ a nanoengineered 3D "nichoid" substrate that mechanically supports CD34 hematopoietic stem and progenitor cells (HSPCs) during ex vivo manipulation, reducing culture-associated stress and improving engraftment and polyclonal output after gene editing or lentiviral gene addition. The work spotlights mechanobiology as a manufacturing lever for improving HSPC gene therapies.
Autosomal recessive congenital ichthyosis (ARCI) refers to a group of rare, highly debilitating skin disorders that significantly impair patients' quality of life and lack any effective treatment options. Here, we report...Autosomal recessive congenital ichthyosis (ARCI) refers to a group of rare, highly debilitating skin disorders that significantly impair patients' quality of life and lack any effective treatment options. Here, we report clinically relevant in situ correction of the most common ARCI-causing mutation, TGM1 c.877-2A>G, a splice-site aberration, in human disease models. Targeted skin barrier modulation followed by topical application of the cytosine base editor eTd packaged into lipid nanoparticles yielded functional restoration of ∼30% of wild-type transglutaminase 1 activity in skin tissue. Toxicity studies and comprehensive off-target analysis demonstrated an excellent safety profile even after repeated application, without systemic distribution of the lipid nanoparticles or the genetic cargo as determined via highly sensitive methods, including desorption electrospray ionization (DESI) metabolic imaging. This study presents comprehensive preclinical data on the feasibility of in situ gene correction of genodermatoses-causing mutations, showcasing its therapeutic potential and paving the way for curative next-generation treatments for severe genetic skin diseases.
Organoids derived from pluripotent stem cells have emerged as powerful models to study human development. To investigate signaling pathways regulating human pancreas differentiation and morphogenesis, we developed a high...Organoids derived from pluripotent stem cells have emerged as powerful models to study human development. To investigate signaling pathways regulating human pancreas differentiation and morphogenesis, we developed a high-content, image-based screen and quantitative multivariate analysis pipelines robust to heterogeneity to extract single-cell and organoid features using pancreatic progenitor organoids. Here, we identified 54 compounds affecting cell identity and/or morphological landscape. Focusing on one family of compounds, we found that glycogen synthase kinase 3α/β (GSK3A/B) inhibition via wingless/int-1 (WNT) signaling has a reversible effect on cell identity, repressing pancreatic progenitor markers and inducing a poised state in progenitors transitioning to acinar cells. We show that additional fibroblast growth factor (FGF) repression enables further differentiation of acinar cells, recapitulating pancreatic acinar morphogenesis and function. The ability to produce acinar cells is valuable for future studies on pancreatic exocrine function and cancer initiation in humans, as acinar cells are thought to be an important cell of origin for pancreatic adenocarcinoma.
The Food and Drug Administration recently announced a plan to phase out animal-testing requirements for drug assessments based on advances in new approach methodologies, including human organ-on-a-chip (Organ Chip) micro...The Food and Drug Administration recently announced a plan to phase out animal-testing requirements for drug assessments based on advances in new approach methodologies, including human organ-on-a-chip (Organ Chip) microfluidic culture technology. Although Organ Chips are being explored in many pharmaceutical laboratories, they have not yet been integrated into drug-development pipelines. Here, I review challenges that must be overcome to bridge this gap and new opportunities that will emerge. I also discuss additional work that will be required for Organ Chips to reduce animal use, lower drug costs, meet regulatory goals, and improve clinical success in the future.
Bartram J, Treichel S, Song BA
… +10 more, Xu J, Sharma D, Nasr W, Frangiosa M, Harley A, Nemkov T, D'Alessandro A, Salomonis N, Grimes HL, Filippi MD
Cell Stem Cell
· 2026 Feb · PMID 41534523
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Adult hematopoietic stem cells (HSCs) sustain the lifelong production of all mature blood and immune cells. HSCs possess extensive regenerative potential, but their self-renewal is limited. A long-standing question has b...Adult hematopoietic stem cells (HSCs) sustain the lifelong production of all mature blood and immune cells. HSCs possess extensive regenerative potential, but their self-renewal is limited. A long-standing question has been why replicative history negatively impacts HSC functions. We found that accrued divisions alter HSC production, generating low-output bone-marrow landscapes that are highly variable in lineage contribution and transcriptionally divergent within individual lineages. Division-driven HSC functional alterations arise from redirecting branched-chain amino acid (BCAA) usage from catabolic toward anabolic activity, causing faster HSC cell-cycle kinetics. Adding a BCAA transamination product overcomes the BCAA catabolic checkpoint and slows down the cell cycle, durably rescuing balanced lineage output of HSCs with accrued divisions. Hence, our study suggests the paradigm whereby replicative history causes metabolic and transcriptional drift, generating divergent HSC output. Division-dependent HSC functional drift can be restored by metabolite replacement, which has long-term therapeutic implications for HSC regenerative medicine.
Spinal cord repair demands biomaterials that replicate the aligned axonal architecture and mechanical softness of native tissue. However, most current scaffolds fail to support three-dimensional alignment and neuronal di...Spinal cord repair demands biomaterials that replicate the aligned axonal architecture and mechanical softness of native tissue. However, most current scaffolds fail to support three-dimensional alignment and neuronal differentiation of human neural stem cells (hNSCs) in hydrated, low-stiffness environments. Here, we present NEAT (nanoengineered extrusion-aligned tract), a shear-stress-driven 3D bioprinting strategy that utilizes norbornene-functionalized collagen (NorCol) to generate highly aligned, mechanically stable hydrogels without post-processing. NEAT preserves the native triple-helical structure of collagen, supports hierarchical fibrillar organization, and enables rapid photopolymerization for long-term culture (>8 weeks). When encapsulated in NEAT constructs, human NSCs exhibited enhanced alignment and accelerated neuronal differentiation, guided by the optimized fibrillar architecture. In a rat model of complete spinal cord transection, NEAT implants promoted robust axonal reconnection, synapse formation, and significant functional locomotor recovery. This strategy bridges topographical control, cellular programming, and functional integration, providing a powerful platform for neural tissue engineering and spinal cord regeneration.
Paulsen B, Barrachina F, Piechota S
… +28 more, Noblett AD, Johnson M, Kats S, Lew C, Marchante M, Figueroa AB, Garcia Granada I, Ingalls Lopez E, Martinez E, Ricra P, Carlos C, Meza J, Montanchez W, Pino P, Reategui C, Noriega E, Elias A, Noriega-Portella L, Haddad G, Radenkovic D, Moran E, Villanueva P, Guiterrez J, Guzman L, Bortolleto P, Albertini DF, De Vos M, Kramme CC
Human induced pluripotent stem cells (hiPSCs) show promise in the development of novel strategies to alleviate reproductive diseases and improve reproductive outcomes. Here, we detail the clinical development and applica...Human induced pluripotent stem cells (hiPSCs) show promise in the development of novel strategies to alleviate reproductive diseases and improve reproductive outcomes. Here, we detail the clinical development and application of an ovarian support cell (OSC) product, Fertilo, to improve the in vitro maturation (IVM) of human oocytes. First, we demonstrate that transcription factor-mediated hiPSC differentiation produces OSCs that improve the oocyte MII maturation rate. To support clinical application, we describe raw material upgrades and the generation of clinically suitable hiPSC seed and master cell banks, with transcriptomic analysis of resultant OSCs showing consistent and reproducible outcomes. Next, we detail analytical release testing and development of a murine oocyte maturation assay to assess product potency. Finally, application of Fertilo in a longitudinal cohort analysis shows improvement in key outcomes, compared with traditional IVM. Our findings demonstrate the first-time clinical development and application of an hiPSC-derived product to promote successful reproductive outcomes.
Retinal organoids are widely used to model human retinal development and disease, but their utility is limited by the absence of vascular networks and stable axonal projections, which contribute to retinal ganglion cell...Retinal organoids are widely used to model human retinal development and disease, but their utility is limited by the absence of vascular networks and stable axonal projections, which contribute to retinal ganglion cell degeneration and loss of function. To address these challenges, we incorporated stem cell-derived endothelial cells to induce transient vascular-like networks and used microfluidic devices to stabilize axonal growth. The resulting organoids showed reduced hypoxia, increased size, and decreased apoptosis, indicating improved long-term survival and maturation of retinal ganglion cells. Integration with microfluidic-microelectrode arrays enabled stable recordings of spontaneous and optogenetically evoked activity, which persisted beyond the time when control organoids lost function. At later stages, these transiently vascularized organoids displayed photoreceptor-driven ON, OFF, and ON-OFF light responses, indicating circuit-level retinal activity. This bioengineered platform establishes a long-term, functional model of the human retina as a transformative tool for retinal research and therapeutic innovation.
Allogeneic cell-based therapies hold great promise for cancer immunotherapy but face challenges like scalability, immune rejection, graft-versus-host disease, and toxicities. Human pluripotent stem cells (hPSCs), includi...Allogeneic cell-based therapies hold great promise for cancer immunotherapy but face challenges like scalability, immune rejection, graft-versus-host disease, and toxicities. Human pluripotent stem cells (hPSCs), including embryonic and induced pluripotent stem cells (iPSCs), offer a scalable and adaptable platform to address these limitations. hPSCs provide an inexhaustible source of immune cells that can be genetically modified at the single-cell level to enhance anti-tumor activity and reduce immunogenicity. Recent advancements in generating iPSC-derived natural killer (NK) cells, T cells, and macrophages are opening the door to safer and more effective immunotherapies. This review examines the progress, challenges, and future directions in utilizing hPSC-derived immune cells to enhance cancer treatment and overcome barriers in allogeneic therapy.
Stierli S, Salas-Bastos A, Micheli S
… +11 more, Ballwein I, Kelemen A, Lehmann J, Loos B, Jordaan WS, Stifter SA, Gwerder M, Nakandalage R, Stadler J, Greter M, Sommer L
Skin repair is a complex, dynamic process involving multiple cell types. Using multiplex imaging, spatial transcriptomics, and single-cell RNA sequencing, we show that peripheral nerves-containing repair glia-form a pro-...Skin repair is a complex, dynamic process involving multiple cell types. Using multiplex imaging, spatial transcriptomics, and single-cell RNA sequencing, we show that peripheral nerves-containing repair glia-form a pro-reparative niche closely interacting with macrophages and proliferating fibroblasts in acute skin wounds. Repair glia function as critical early-stage regulators of wound healing by initiating the inflammatory response through secretion of monocyte chemoattractant proteins, such as CCL2, which recruit monocyte-derived macrophages. Accordingly, depletion of repair glia as well as glia-specific deletion of CCL2 reduces the number of macrophages, leading to impaired fibroblast proliferation and diminished fibroblast-to-myofibroblast transition. These findings identify repair glia as early regulators of the immune response, orchestrating the spatiotemporal progression of wound healing.
Midena F, Alessandrini L, Conci C
… +33 more, Barcella M, Gazzo F, Jacchetti E, Carsana E, Benedicenti F, Vacca R, Della Volpe L, Arévalo S, Giannetti K, Barozzi D, Franchino M, Zonari E, Ferrua F, Farina G, Brombin C, Cugnata F, Fiumara M, Tavella T, Cherubin L, Fraschetta F, Cerullo G, Osellame R, Radrizzani M, Ferrari S, Merelli I, Gentner B, Scielzo C, Brendolan A, Naldini L, Aiuti A, Montini E, Raimondi MT, Di Micco R
Cell Stem Cell
· 2026 Feb · PMID 41512872
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Full text
Ex vivo culture of hematopoietic stem and progenitor cells (HSPCs) is required for gene therapy applications but inadvertently triggers detrimental cellular responses, potentially threatening clinical success. In this st...Ex vivo culture of hematopoietic stem and progenitor cells (HSPCs) is required for gene therapy applications but inadvertently triggers detrimental cellular responses, potentially threatening clinical success. In this study, we employ nichoids, biocompatible 3D culture substrates with cell-scale resolution, to provide HSPCs with mechanical support during ex vivo manipulation. This innovative 3D system improves HSPC multi-lineage differentiation and engraftment capacity by leveraging mechanobiological control over nuclear morphology, cytoskeleton organization, metabolism, and DNA integrity. Notably, 3D culture enables efficient genetic engineering across multiple platforms, including long-range gene editing, base- and prime-editing, and lentiviral-mediated gene addition. Moreover, this scaffold increases the clonal output and persistence of genetically engineered cells in xenotransplantation experiments, including a clinical protocol for lentiviral gene addition in Wiskott-Aldrich syndrome. Overall, we propose a transformative approach to enhance the efficacy and safety of emerging and established hematopoietic stem cell-based gene therapy applications.
Allogeneic T cell therapies are a highly desirable option to circumvent the cost and complexity of using autologous T cells to treat diseases. Allogeneic CD8 T cells can be made from pluripotent stem cells (PSCs), but de...Allogeneic T cell therapies are a highly desirable option to circumvent the cost and complexity of using autologous T cells to treat diseases. Allogeneic CD8 T cells can be made from pluripotent stem cells (PSCs), but deriving CD4 T cells from PSCs has remained a significant challenge. Using feeder- and serum-free conditions, we found that CD4 vs. CD8 T cell commitment from PSCs can be controlled by fine-tuning the dynamics of Notch and T cell receptor (TCR) signaling delivered to CD4CD8 double-positive T cells. Notch signaling negatively impacts CD4 T cell commitment, and its timed removal allows generation of clonally diverse and expandable CD4 T cells from PSCs. The resulting CD4 T cells respond to cytokine-mediated polarization by differentiating into Th1, Th2, or Th17 cells, recapitulating canonical helper cell function. These findings represent a significant step toward using PSC-derived CD4 T cells as a low-cost, off-the-shelf cell therapy.
In this issue of Cell Stem Cell, Zhang et al. identify a pathological NTRK2 isoform switch in bronchopulmonary dysplasia that alters the regenerative capacity of capillary endothelial cells, highlighting isoform-specific...In this issue of Cell Stem Cell, Zhang et al. identify a pathological NTRK2 isoform switch in bronchopulmonary dysplasia that alters the regenerative capacity of capillary endothelial cells, highlighting isoform-specific targeting as a promising strategy for vascular repair..
Neural transplantation holds the potential to repair damaged neural circuits in neurological diseases. However, it remains unknown how the grafted neurons project axons to and make functional connections with the appropr...Neural transplantation holds the potential to repair damaged neural circuits in neurological diseases. However, it remains unknown how the grafted neurons project axons to and make functional connections with the appropriate targets to repair the damaged circuit at the adult stage. Here, we report that human cortical progenitors, transplanted into the ischemic mouse motor cortex, matured and integrated into cortical and subcortical neural circuits, including the corticospinal tract. Neuronal tracing combined with single-nuclei RNA sequencing revealed the close relationship between the transcription profiles of a cortical neuronal subtype, especially those of axon guidance and synapse assembly, with the specific target projection and synapse organization. Machine learning-based regression further identified the transcriptional codes for the targeted projection and circuit integration to reconstruct the damaged circuits. Our finding opens a promising strategy for treating neurological diseases through promoting regeneration and neural transplantation.
Human pineal development and neuroendocrine regulation remain incompletely understood at the molecular and functional levels. Kiral et al. establish human pineal gland organoids (hPGOs) that recapitulate pinealocyte matu...Human pineal development and neuroendocrine regulation remain incompletely understood at the molecular and functional levels. Kiral et al. establish human pineal gland organoids (hPGOs) that recapitulate pinealocyte maturation, noradrenergic responsiveness, and melatonin synthesis, providing a platform for investigating circadian dysfunction and disease-associated sleep disturbances.
Aging is characterized by a progressive decline in physiological function, driven by interconnected molecular hallmarks that increase the risk of chronic diseases. To extend health span, interventions targeting these hal...Aging is characterized by a progressive decline in physiological function, driven by interconnected molecular hallmarks that increase the risk of chronic diseases. To extend health span, interventions targeting these hallmarks, including lifestyle modifications, pharmacological agents, and genetic strategies, have been developed. Among these, partial reprogramming, the transient expression of Yamanaka factors, has emerged as a powerful approach to reverse age-related cellular damage and restore youthful epigenetic and transcriptional signatures without erasing cell identity. This perspective highlights the therapeutic possibilities arising from the convergence of partial reprogramming with the innovative technology of ex vivo machine perfusion. These platforms offer a unique opportunity to apply rejuvenation therapies directly to suboptimal donor organs outside the body before transplantation. Combining these strategies could significantly improve organ quality, expand the donor pool, enhance transplantation outcomes, and advance regenerative medicine.
Editors' note: The Ogawa-Yamanaka Stem Cell Prize recognizes groundbreaking work in translational regenerative medicine using reprogrammed cells. The prize is supported by Gladstone Institutes, in partnership with Cell P...Editors' note: The Ogawa-Yamanaka Stem Cell Prize recognizes groundbreaking work in translational regenerative medicine using reprogrammed cells. The prize is supported by Gladstone Institutes, in partnership with Cell Press. Among his myriad accomplishments, Rudolf Jaenisch-winner of the 2025 Ogawa-Yamanaka Stem Cell Prize-was the first to demonstrate the potential of induced pluripotent stem cells to treat disease.
Liu et al. generate human sympathetic ganglion organoids and assemble them with heart-forming organoids to build functionally connected sympathetic-cardiac organoids in vitro. Their platform captures autonomic developmen...Liu et al. generate human sympathetic ganglion organoids and assemble them with heart-forming organoids to build functionally connected sympathetic-cardiac organoids in vitro. Their platform captures autonomic development, neuromodulation of heart function, and metabolic injury, opening new opportunities to study human autonomic disorders and cardiometabolic disease..