The research, led by Lingting Shi, Ajna Uzuni and Ximi K. Wang under the joint supervision of Elham Azizi and Ran Reshef at Columbia University, followed 31 transplant recipients using an integrated spatiotemporal framework. The team combined longitudinal T cell antigen receptor profiling with single-cell RNA sequencing paired with TCR sequencing and spatial transcriptomics, allowing them to track the fate of specific alloreactive T cell clones from the bloodstream into the gut epithelium, where the most lethal manifestations of graft-versus-host disease occur.

A central methodological innovation was DecompTCR, a computational tool developed by the team to resolve the temporal dynamics of T cell clonal expansion from bulk TCR repertoire data. The researchers also adapted existing computational approaches to map clone phenotypes and their tissue niches, including StarfyshHD for spatial deconvolution of high-resolution spatial transcriptomic data and DecipherTCR for joint representation of clonal states. Together, these tools allowed the investigators to ask not merely which T cell clones were present, but when they expanded, what programs they expressed and where they accumulated within damaged tissue.

One of the study’s most clinically consequential findings concerns post-transplantation cyclophosphamide, a widely used prophylactic strategy in which high-dose chemotherapy is administered shortly after infusion of the donor graft. The time-resolved modeling revealed that cyclophosphamide does indeed selectively deplete alloreactive T cell clones, validating the biological rationale behind the intervention. However, the data also exposed a critical vulnerability: when early expansion of alloreactive clones is insufficient, the depletion is incomplete, and residual surviving clones can seed severe disease. This finding reframes the drug’s success or failure as a matter of clonal population dynamics rather than simple toxicity.

Patients who went on to develop severe graft-versus-host disease were distinguished by persistent expansion of alloreactive clones in the blood, accompanied by increased clonal diversity among the expanding populations. The team’s analyses showed that severe disease was also marked by a rewiring of homeostatic cell types, suggesting that the alloimmune attack does not simply destroy tissue but actively remodels the cellular ecosystem of the affected organ. These early-repertoire dynamics, the authors propose, could serve as biomarkers to identify high-risk patients before clinical symptoms escalate.

Perhaps the most striking discovery emerged from tracking donor-derived CD8-positive clonotypes as they migrated into epithelial tissue. During this migration, the clones underwent a remarkable phenotypic transformation, diversifying and acquiring Hobit-positive tissue-resident memory T cell programs, marked by expression of the transcription factor ZNF683. This plasticity means that the same alloreactive clone can exist in fundamentally different functional states depending on its location, shifting from a circulating effector into a tissue-embedded resident cell that is far harder to eliminate with systemic therapies.

Spatial transcriptomic analysis then revealed where these transformed cells wreak their damage. Using spatial deconvolution, the researchers identified hubs of CD8-positive effector and Hobit-positive tissue-resident memory T cells clustered near intestinal stem-cell-rich crypt bases and in regions of crypt loss. This anatomical positioning is devastating in its implications: intestinal stem cells are essential for regenerating the epithelial barrier, and their destruction by neighboring cytotoxic T cells undermines the gut’s capacity for repair. The study thereby links tissue-instructed tissue-resident memory remodeling directly to localized epithelial injury, providing a mechanistic bridge between clonal immune dynamics and the clinical pathology of gastrointestinal graft-versus-host disease.

The framework also documented collaborative immune responses within crypt-loss regions, where multiple cell types appeared to act in concert to drive tissue destruction. By resolving these interactions at clonotype level, the study moves the field beyond the traditional view of graft-versus-host disease as a diffuse inflammatory process and toward a model in which discrete, spatially organized immune hubs determine where and how severely tissue damage occurs. The burden of these spatial hubs, the authors suggest, may itself serve as a measurable biomarker of disease severity.

The translational implications are substantial. If early clonal expansion dynamics in the blood can predict which patients will progress to severe disease, clinicians could intensify prophylaxis or intervene earlier in those at highest risk, while sparing others unnecessary immunosuppression. The identification of Hobit-positive tissue-resident memory programs as drivers of epithelial injury also nominates new therapeutic targets, since strategies that prevent T cells from adopting residency programs or that dislodge established resident populations could complement existing approaches such as costimulation blockade with abatacept and other prophylactic regimens under clinical evaluation.

All data generated in the study have been deposited in the Gene Expression Omnibus under accession number GSE307215, and the analysis code is publicly available, enabling the broader research community to build on this clonotype-resolved framework. As single-cell and spatial technologies continue to mature, this work offers a template for dissecting other immune-mediated conditions, from inflammatory bowel disease to solid organ transplant rejection, where the same principles of clonal tracking, phenotypic plasticity and spatial mapping are likely to illuminate how destructive immune responses take root in human tissue.

Subject of Research: Spatiotemporal single-cell profiling of alloreactive T cell clonal dynamics and phenotypic plasticity in human graft-versus-host disease

Article Title: Spatiotemporal single-cell profiling reveals T cell clonal dynamics and phenotypic plasticity in human graft-versus-host disease

Article References: Shi, L., Uzuni, A., Wang, X. K., Pressler, M., Harle, D. W., Chakrabarti, S., Macedo, R., Belay, K., Gordillo, C. A., McMahon-Skates, T., Raps, E., Zhang, J. Y. A., Nazaret, A., Fan, J. L., Jin, Y., Shen, X., Fuller, J. S., Azad, T., Huang, J., … Reshef, R. (2026). Spatiotemporal single-cell profiling reveals T cell clonal dynamics and phenotypic plasticity in human graft-versus-host disease. Nature Immunology. https://doi.org/10.1038/s41590-026-02631-2

Image Credits: AI Generated

DOI: 10.1038/s41590-026-02631-2

Keywords: graft-versus-host disease, hematopoietic cell transplantation, single-cell RNA sequencing, T cell receptor profiling, tissue-resident memory T cells, spatial transcriptomics, alloreactive T cells, cyclophosphamide, intestinal stem cells, clonal dynamics, transplant immunology, Hobit ZNF683

The clinical stakes could hardly be higher. Congenital diarrheas and enteropathies are a group of inherited disorders that strike in the first weeks or months of life, often leaving infants dependent on intravenous nutrition and, in the most severe cases, candidates for intestinal transplantation. Diarrhea-9, caused by loss-of-function mutations in WNT2B, is among the most extreme of these conditions. Yet attempts to model the disease in rodents have fallen short, and studying epithelial tissue taken directly from patients has not fully captured the human phenotype. This gap between mouse and human biology is precisely what the new study set out to close by building the disease in a dish, using human cells that carry the very mutation found in patients.

The research team generated induced pluripotent stem cells from a patient carrying a specific nonsense mutation in WNT2B, designated WNT2B R69*, a single DNA base change that introduces a premature stop signal and truncates the protein. These patient-derived stem cells were then coaxed through the elaborate choreography of intestinal development, first into definitive endoderm and ultimately into three-dimensional human intestinal organoids, or HIOs, which contain both the epithelial lining of the gut and its surrounding mesenchymal support tissue. Quality-control assays, including karyotyping, STR profiling and pluripotency scorecard testing, confirmed that the patient-derived line behaved like a healthy stem cell line in every respect except the one under investigation: the WNT2B mutation itself.

When the researchers examined the WNT2B-deficient organoids under live and histological imaging, a striking abnormality emerged. The organoids showed partial epithelial delamination, meaning that cells of the intestinal lining were detaching and peeling away from their proper positions, a defect entirely absent in control organoids derived from healthy stem cells. Delamination of the epithelium is a catastrophic problem for an organ whose function depends on an intact, continuous barrier between the body and the outside world. It provides a direct structural explanation for the severe malabsorption and fluid loss that characterize Diarrhea-9 in affected infants.

The damage extended deep into the regenerative engine of the intestine. A significant fraction of the crypt-like structures in WNT2B-deficient organoids lacked olfactomedin 4, or OLFM4, a well-established surrogate marker of active intestinal stem cell function. Because the intestinal lining turns over every few days in healthy tissue, sustained stem cell activity is essential for maintaining the barrier. The loss of OLFM4 signal suggests that WNT2B deficiency undermines the stem cell compartment, potentially compounding the structural defects with a failure of repair and renewal. Further characterization of secretory lineages, including Paneth cells marked by lysozyme, goblet cells marked by mucin 2, and enteroendocrine cells marked by chromogranin A, allowed the team to assess whether specific differentiated cell types were selectively lost, painting a detailed cellular census of the diseased tissue.

Beyond structure, the study probed function at the molecular level. Transcriptomic analysis comparing WNT2B-deficient and control organoids identified a set of significantly altered biological pathways, among the most notable being the trafficking of apical digestion proteins, the molecular machinery that delivers digestive enzymes such as sucrase isomaltase to the microvillar surface of the epithelium where nutrients are absorbed. Immunofluorescence staining confirmed these transcriptional findings visually, showing mislocalized digestion machinery in the mutant tissue. Proteomic analysis of enteroids derived from the patient’s own tissue revealed a broadly similar pattern of disruption, providing independent lines of evidence that WNT2B loss derails both the logistics of digestion and the integrity of the epithelial barrier. Additional analyses of epithelial junction and barrier-associated genes, including tight junction components, adherens junction genes and epithelial keratins, further mapped the molecular consequences of the mutation.

Perhaps the most conceptually important experiment involved organoid recombination, a technique that allowed the researchers to build chimeric organoids with mixed origins: normal epithelium paired with WNT2B-deficient mesenchyme, or mutant epithelium paired with normal mesenchyme. The results were unambiguous. When the mesenchyme lacked WNT2B, the resulting organoids showed a far more pronounced disruption of epithelial architecture and organization than when the epithelium itself carried the defect. In other words, the surrounding connective tissue compartment, not the lining cells alone, is the dominant driver of the structural collapse seen in Diarrhea-9. This finding reframes the disease as a disorder of the gut’s supporting niche as much as of its absorptive surface.

This compartment-specific conclusion carries broad implications for developmental biology. Wnt signaling is one of the fundamental patterning systems of the animal body, and WNT2B is expressed in the mesenchyme underlying the intestinal epithelium, where it has been suspected of nurturing stem cells and organizing tissue architecture. The new data demonstrate that in humans, the mesenchymal source of WNT2B is not a redundant backup but a critical instructive signal for the epithelium. They also help explain why mouse models have failed to capture the human disease: the division of labor between epithelial and mesenchymal Wnt sources appears to differ between species, making human organoid systems not merely convenient but essential for studying this condition.

The study also delivers a methodological message that resonates well beyond Diarrhea-9. Human intestinal organoids, and in particular transplanted human intestinal organoids that mature in vivo and can later be harvested as enteroids for functional experiments, proved capable of reproducing a human-specific intestinal disorder that rodents could not. Functional assays on enteroids derived from the organoids, including responses to forskolin that trigger fluid secretion, demonstrated that the model system supports physiological testing, not just static observation. As organoid platforms proliferate across biomedical research, this work stands as a case study in how patient-derived stem cells can illuminate rare diseases that have resisted conventional modeling for decades.

For families affected by congenital diarrheas, the research offers a clearer mechanistic map of what has gone wrong and a credible experimental platform for testing future interventions. By pinpointing the mesenchyme as the critical compartment and identifying stem cell exhaustion, epithelial delamination and defective trafficking of digestive proteins as downstream consequences of WNT2B loss, the study defines concrete targets for therapy development, whether through small molecules that bolster epithelial resilience, niche-supporting factors that substitute for missing Wnt signals, or gene-based approaches that correct the underlying mutation. It also underscores the value of international collaboration among pediatric hospitals, stem cell facilities and proteomics cores in tackling diseases so rare that no single institution could assemble the evidence alone. As the organoid revolution matures, studies of this kind are transforming rare genetic disorders from unsolvable mysteries into tractable engineering problems, one miniature human gut at a time.

Subject of Research: Compartment-specific roles of the WNT2B signaling gene in human intestinal development and congenital diarrhea

Article Title: Compartment-specific roles for WNT2B in human intestinal development and function

Article References: Compartment-specific roles for WNT2B in human intestinal development and function. (n.d.). https://doi.org/10.1186/s12915-026-02724-2

Image Credits: AI Generated

DOI: 10.1186/s12915-026-02724-2

Keywords: WNT2B, congenital diarrhea, human intestinal organoids, intestinal stem cells, mesenchyme, epithelium, Diarrhea-9, organoid recombination, BMC Biology, developmental biology, enteroids, rare disease

The consortium’s central message is that the intestinal stem cell is not a fixed identity but a flexible state dictated by its surroundings. Historically, researchers divided intestinal stem cells into two camps: actively self-renewing cells marked by the gene Lgr5, which continuously fuel the everyday turnover of the epithelium, and a facultative or ‘reserve’ population, sometimes called revival stem cells, that normally rests but springs into action after catastrophic injury. Landmark studies identified Bmi1, Hopx, and other markers for these reserve cells, and work by Tian and colleagues showed that a reserve population could render Lgr5-positive cells dispensable under certain conditions. The new Roadmap argues that neither population is intrinsically determined; rather, homeostatic and regenerative properties emerge from signals emanating from a specialized local niche, the microenvironment that cradles the stem cells and instructs their behavior.

That niche has turned out to be far more complex than early models suggested. In the small intestine, Paneth cells interdigitated among the stem cells at the crypt base supply Wnt ligands, antimicrobial peptides, and metabolic support, although studies by Kim, Escudero, and Shivdasani demonstrated that Lgr5 stem cells can function even without Paneth cells, pointing to redundant support systems. Surrounding the crypts lies a constellation of mesenchymal cell types, each with distinct jobs. PDGFRα-positive pericryptal stromal cells and GLI1-expressing cells serve as critical sources of Wnts and the Wnt-amplifying protein RSPO3, while FOXL1-positive telocytes, CD34-positive mesenchymal cells, and distinct smooth muscle layers contribute additional Wnt ligands, bone morphogenetic protein gradients, and structural organization. Graded BMP signaling within the crypt architecture, as shown by Kraiczy and colleagues, even directs the self-organization of the Wnt-secreting niche itself, revealing an intricate feedback loop between epithelium and stroma.

Beyond fibroblasts, the consortium highlights an expanding cast of niche regulators. Lymphatic vessels act as signaling hubs, with lymphangiocrine signals required for proper repair after cytotoxic injury. Enteric glial cells, macrophages, and type 3 innate lymphoid cells all modulate stem cell activity, the latter through the cytokine interleukin-22, which promotes stem-cell-mediated epithelial regeneration and protects stem cells from immune-mediated damage. Even nerves participate: adrenergic nerves regulate intestinal regeneration through IL-22 signaling from innate lymphoid cells, and nociceptive neurons have been implicated in tumor progression via a CGRP-RAMP1 axis. Mechanosensing adds another dimension, with PIEZO-dependent mechanical signals proving essential for stem cell fate decisions. The picture that emerges is of a layered, multi-tissue ecosystem in which epithelial, mesenchymal, immune, vascular, lymphatic, and neural components jointly govern when stem cells divide, differentiate, or revert to a fetal-like regenerative program.

Cellular plasticity sits at the heart of this regenerative capacity. When Lgr5-positive stem cells are ablated, a remarkable variety of differentiated and progenitor cells can dedifferentiate and rebuild the stem cell compartment. Dll1-positive secretory progenitors, enterocyte-lineage daughters, Paneth cells responding to Notch activation, enteroendocrine lineage cells, and even tuft cells, which Huang and colleagues showed act as regenerative stem cells in the human intestine, have all been documented to revert. Single-cell transcriptomics revealed a revival stem cell state marked by fetal programs, and parasitic helminths were found to induce fetal-like reversion in the niche as part of the immune response. Chromatin studies explain how this is possible: the intestinal epithelium maintains broadly permissive chromatin that allows rapid switching between lineages, while factors such as Ascl2, ATOH1 phosphorylation, and Frizzled5-controlled chromatin accessibility orchestrate the dedifferentiation process. In disease, this plasticity is a double-edged sword, since the same reserve and revival programs that heal wounds can seed radioresistant, cancer-initiating populations.

Translating this biology into therapies has been propelled by organoid technology, one of the field’s transformative breakthroughs. In 2009, Sato and colleagues showed that single Lgr5 stem cells could build crypt-villus structures in vitro without a mesenchymal niche, and Ootani’s team sustained intestinal epithelium in a Wnt-dependent stem cell culture system the same year. Human colon, adenoma, and Barrett’s epithelium organoids followed in 2011, as did the directed differentiation of human pluripotent stem cells into intestinal tissue by Spence and colleagues. The technology has since matured dramatically: scaffold-guided morphogenesis produces homeostatic mini-intestines, organoid-derived tissues have repaired damaged bowel in vivo, patient-derived jejunal mucosal grafts have been engineered from children with intestinal failure, and organ-repurposing approaches have treated short bowel syndrome in preclinical models. Human intestinal organoids transplanted into humanized mice develop immune tissue, and coordinated differentiation protocols now generate organoids with functional enteric neurons and vasculature, bringing engineered gut tissue closer to clinical reality.

The consortium also emphasizes how organoids and microfluidic gut-on-a-chip systems have become indispensable for studying host-pathogen interactions. Complex human gut microbiomes have been cultured in anaerobic intestine-on-a-chip devices, and human colon models have revealed uncoupled apical and basal cytotoxicity during early Clostridioides difficile toxin exposure. These platforms allow researchers to interrogate how pathogens reshape the stem cell compartment and how microbial metabolites, such as microbiota-derived lactate, accelerate stem-cell-mediated epithelial development. Innate immune receptors on the stem cells themselves, including Toll-like receptor 4 and NOD2, which protects LGR5-positive cells from reactive oxygen species through mitophagy, directly link microbial sensing to regenerative capacity, suggesting that microbiome manipulation could become a therapeutic lever for mucosal healing.

Pharmacological strategies form the second pillar of the therapeutic roadmap. R-spondin ligands, potent amplifiers of Wnt signaling, have been shown to induce intestinal stem cells, augment chemoradioprotection, promote colonic regeneration, and ameliorate experimental colitis, while surrogate Wnt agonists that phenocopy canonical signaling support organoid growth and show promise for FZD-specific activation of repair pathways. Glucagon-like peptide-2 agonists, already approved for short bowel syndrome, stimulate S-phase entry of Lgr5-positive stem cells and support stem cell and Paneth cell repair during graft-versus-host disease, with newer agents such as glepaglutide showing anti-inflammatory and mucosal regenerative effects. Structure-based design has even decoupled the tissue-protective functions of interleukin-22 from its pro-inflammatory actions, opening the door to safer regenerative cytokine therapies. The consortium cautions, however, that stimulating proliferation carries oncogenic risk, and that niche dysregulation is predicted to underlie compromised regeneration in conditions such as inflammatory bowel disease, where stem cells retain epigenetic memories of inflammation.

The Roadmap closes with a candid inventory of remaining knowledge gaps. Human intestinal stem cells differ from their mouse counterparts in ways that matter for therapy, and spatial atlases of the adult human intestine, single-cell maps of human development, and spatial transcriptomic surveys of regeneration are only now filling the void. Bioengineered colon organoids with in vivo-like complexity, bioprinted tissues recapitulating macro-scale self-organization, and instant collagen assembly for tissue engineering are pushing manufacturing capabilities forward, while lessons from the first pluripotent stem cell therapies entering the clinic, including stem-cell-derived islets for diabetes and retinal cells for macular degeneration, offer a template for regulatory and safety pathways. What the ISCC’s fifteen-year arc demonstrates is that the intestine, once considered too dynamic and complex to rebuild, has yielded its construction secrets to systematic, collaborative biology. The remaining challenge is engineering: assembling niche cells, immune compartments, vasculature, and nerves into transplantable tissue that can survive, integrate, and function in patients whose own guts can no longer keep pace. If the consortium’s roadmap holds, the era of stem-cell-built intestines may be closer than anyone dared predict when the effort began.

Subject of Research: Intestinal stem cell biology and stem cell-based strategies for intestinal regeneration and tissue engineering

Article Title: Building and regenerating intestines by manipulating intestinal stem cells

Article References: Building and regenerating intestines by manipulating intestinal stem cells. (n.d.). https://doi.org/10.1038/s41575-026-01242-4

Image Credits: AI Generated

DOI: 10.1038/s41575-026-01242-4

Keywords: intestinal stem cells, stem cell niche, organoids, epithelial regeneration, Wnt signaling, R-spondin, interleukin-22, cellular plasticity, short bowel syndrome, inflammatory bowel disease, tissue engineering, Intestinal Stem Cell Consortium