All Publications

  • Dopaminergic neurons entering the brain under the immunological cover of darkness. Cell stem cell Chai, T., Chen, J. Y., Loh, K. M. 2025; 32 (5): 675-677

    Abstract

    The ability to transplant immunologically foreign cells into an animal without immune suppression would be transformative. Pavan et al. show that human pluripotent stem cell-derived dopaminergic neuron progenitors engineered to express eight immune-evasive proteins can engraft in humanized mice and a rat model of Parkinson's disease without recourse to immune suppression.1.

    View details for DOI 10.1016/j.stem.2025.04.004

    View details for PubMedID 40315830

  • TMX1, a disulfide oxidoreductase, is necessary for T cell function through regulation of CD3ζ. bioRxiv : the preprint server for biology Chai, T., Loh, K. M., Weissman, I. L. 2024

    Abstract

    T cell-targeted therapies are commonly used to manage T cell hyperactivity in autoimmune disorders, graft-versus-host diseases (GVHD), and transplant rejections. However, many patients experience significant side effects or inadequate responses to current treatments, highlighting the urgent need for alternative strategies. In this study, we searched for regulators of T cells through proximity labeling with APEX2 to detect proteins interacting with CD8α, a coreceptor of the T-cell receptor (TCR). This screen revealed TMX1, an ER resident transmembrane disulfide oxidoreductase, is essential for T cell cytotoxicity and NFAT, NFκB, and AP1 signaling but not cell proliferation. TMX1 deletion decreases surface TCR expression and destabilizes CD3ζ, a subunit of TCR complex; however, overexpression of CD3ζ rescues the phenotype, suggesting that TMX1 is not required for CD3ζ function. Mechanistically, TMX1 was found to directly engage the CxxC motif of CD3δ, which has been reported to be essential for proper TCR assembly and function. We hypothesize that the loss of TMX1 interaction with CD3δ leads to impaired TCR assembly and subsequent CD3ζ destabilization. These findings identify TMX1 as a novel regulator of T-cell receptor assembly and a potential target for immunosuppressive therapy.

    View details for DOI 10.1101/2024.09.22.614388

    View details for PubMedID 39386445

    View details for PubMedCentralID PMC11463681

  • Lineage-tracing hematopoietic stem cell origins in vivo to efficiently make human HLF+ HOXA+ hematopoietic progenitors from pluripotent stem cells. Developmental cell Fowler, J. L., Zheng, S. L., Nguyen, A., Chen, A., Xiong, X., Chai, T., Chen, J. Y., Karigane, D., Banuelos, A. M., Niizuma, K., Kayamori, K., Nishimura, T., Cromer, M. K., Gonzalez-Perez, D., Mason, C., Liu, D. D., Yilmaz, L., Miquerol, L., Porteus, M. H., Luca, V. C., Majeti, R., Nakauchi, H., Red-Horse, K., Weissman, I. L., Ang, L. T., Loh, K. M. 2024

    Abstract

    The developmental origin of blood-forming hematopoietic stem cells (HSCs) is a longstanding question. Here, our non-invasive genetic lineage tracing in mouse embryos pinpoints that artery endothelial cells generate HSCs. Arteries are transiently competent to generate HSCs for 2.5 days (∼E8.5-E11) but subsequently cease, delimiting a narrow time frame for HSC formation in vivo. Guided by the arterial origins of blood, we efficiently and rapidly differentiate human pluripotent stem cells (hPSCs) into posterior primitive streak, lateral mesoderm, artery endothelium, hemogenic endothelium, and >90% pure hematopoietic progenitors within 10 days. hPSC-derived hematopoietic progenitors generate T, B, NK, erythroid, and myeloid cells in vitro and, critically, express hallmark HSC transcription factors HLF and HOXA5-HOXA10, which were previously challenging to upregulate. We differentiated hPSCs into highly enriched HLF+ HOXA+ hematopoietic progenitors with near-stoichiometric efficiency by blocking formation of unwanted lineages at each differentiation step. hPSC-derived HLF+ HOXA+ hematopoietic progenitors could avail both basic research and cellular therapies.

    View details for DOI 10.1016/j.devcel.2024.03.003

    View details for PubMedID 38569552

  • UCHL1 is a potential molecular indicator and therapeutic target for neuroendocrine carcinomas. Cell reports. Medicine Liu, S., Chai, T., Garcia-Marques, F., Yin, Q., Hsu, E. C., Shen, M., Shaw Toland, A. M., Bermudez, A., Hartono, A. B., Massey, C. F., Lee, C. S., Zheng, L., Baron, M., Denning, C. J., Aslan, M., Nguyen, H. M., Nolley, R., Zoubeidi, A., Das, M., Kunder, C. A., Howitt, B. E., Soh, H. T., Weissman, I. L., Liss, M. A., Chin, A. I., Brooks, J. D., Corey, E., Pitteri, S. J., Huang, J., Stoyanova, T. 2024: 101381

    Abstract

    Neuroendocrine carcinomas, such as neuroendocrine prostate cancer and small-cell lung cancer, commonly have a poor prognosis and limited therapeutic options. We report that ubiquitin carboxy-terminal hydrolase L1 (UCHL1), a deubiquitinating enzyme, is elevated in tissues and plasma from patients with neuroendocrine carcinomas. Loss of UCHL1 decreases tumor growth and inhibits metastasis of these malignancies. UCHL1 maintains neuroendocrine differentiation and promotes cancer progression by regulating nucleoporin, POM121, and p53. UCHL1 binds, deubiquitinates, and stabilizes POM121 to regulate POM121-associated nuclear transport of E2F1 and c-MYC. Treatment with the UCHL1 inhibitor LDN-57444 slows tumor growth and metastasis across neuroendocrine carcinomas. The combination of UCHL1 inhibitors with cisplatin, the standard of care used for neuroendocrine carcinomas, significantly delays tumor growth in pre-clinical settings. Our study reveals mechanisms of UCHL1 function in regulating the progression of neuroendocrine carcinomas and identifies UCHL1 as a therapeutic target and potential molecular indicator for diagnosing and monitoring treatment responses in these malignancies.

    View details for DOI 10.1016/j.xcrm.2023.101381

    View details for PubMedID 38244540

  • Generating human artery and vein cells from pluripotent stem cells highlights the arterial tropism of Nipah and Hendra viruses. Cell Ang, L. T., Nguyen, A. T., Liu, K. J., Chen, A., Xiong, X., Curtis, M., Martin, R. M., Raftry, B. C., Ng, C. Y., Vogel, U., Lander, A., Lesch, B. J., Fowler, J. L., Holman, A. R., Chai, T., Vijayakumar, S., Suchy, F. P., Nishimura, T., Bhadury, J., Porteus, M. H., Nakauchi, H., Cheung, C., George, S. C., Red-Horse, K., Prescott, J. B., Loh, K. M. 2022

    Abstract

    Stem cell research endeavors to generate specific subtypes of classically defined "cell types." Here, we generate >90% pure human artery or vein endothelial cells from pluripotent stem cells within 3-4 days. We specified artery cells by inhibiting vein-specifying signals and vice versa. These cells modeled viral infection of human vasculature by Nipah and Hendra viruses, which are extraordinarily deadly (∼57%-59% fatality rate) and require biosafety-level-4 containment. Generating pure populations of artery and vein cells highlighted that Nipah and Hendra viruses preferentially infected arteries; arteries expressed higher levels of their viral-entry receptor. Virally infected artery cells fused into syncytia containing up to 23 nuclei, which rapidly died. Despite infecting arteries and occupying ∼6%-17% of their transcriptome, Nipah and Hendra largely eluded innate immune detection, minimally eliciting interferon signaling. We thus efficiently generate artery and vein cells, introduce stem-cell-based toolkits for biosafety-level-4 virology, and explore the arterial tropism and cellular effects of Nipah and Hendra viruses.

    View details for DOI 10.1016/j.cell.2022.05.024

    View details for PubMedID 35738284

  • Dach1 Extends Artery Networks and Protects Against Cardiac Injury. Circulation research Raftrey, B., Williams, I. M., Rios Coronado, P. E., Fan, X., Chang, A. H., Zhao, M., Roth, R. K., Trimm, E., Racelis, R., D'Amato, G., Phansalkar, R., Nguyen, A., Chai, T., Gonzalez, K. M., Zhang, Y., Ang, L. T., Loh, K., Bernstein, D., Red-Horse, K. 2021

    Abstract

    Rationale: Coronary artery disease (CAD) is the leading cause of death worldwide, but there are currently no methods to stimulate artery growth or regeneration in diseased hearts. Studying how arteries are built during development could illuminate strategies for re-building these vessels during ischemic heart disease. We previously found that Dach1 deletion in mouse embryos resulted in small coronary arteries. However, it was not known whether Dach1 gain-of-function would be sufficient to increase arterial vessels and whether this could benefit injury responses. Objective: We investigated how Dach1 overexpression in endothelial cells affected transcription and artery differentiation, and how it influenced recovery from myocardial infarction (MI). Methods and Results: Dach1 was genetically overexpressed in coronary endothelial cells (ECs) in either developing or adult hearts using ApjCreER. This increased the length and number of arterial end branches expanded arteries during development, in both the heart and retina, by inducing capillary ECs to differentiate and contribute to growing arteries. Single-cell RNA sequencing (scRNAseq) of ECs undergoing Dach1-induced arterial specification indicated that it potentiated normal artery differentiation, rather than functioning as a master regulator of artery cell fate. ScRNAseq also showed that normal arterial differentiation is accompanied by repression of lipid metabolism genes, which were also repressed by Dach1. In adults, Dach1 overexpression did not cause a statistically significant change artery structure prior to injury, but increased the number of perfused arteries in the injury zone post-MI. Conclusions: Our data demonstrate that increasing Dach1 is a novel method for driving artery specification and extending arterial branches, which could be explored as a means of mitigating the effects of CAD.

    View details for DOI 10.1161/CIRCRESAHA.120.318271

    View details for PubMedID 34383559

  • CD47 prevents the elimination of diseased fibroblasts in scleroderma. JCI insight Lerbs, T., Cui, L., King, M. E., Chai, T., Muscat, C., Chung, L., Brown, R., Rieger, K., Shibata, T., Wernig, G. 2020; 5 (16)

    Abstract

    Scleroderma is a devastating fibrotic autoimmune disease. Current treatments are partly effective in preventing disease progression but do not remove fibrotic tissue. Here, we evaluated whether scleroderma fibroblasts take advantage of the "don't-eat-me-signal" CD47 and whether blocking CD47 enables the body's immune system to get rid of diseased fibroblasts. To test this approach, we used a Jun-inducible scleroderma model. We first demonstrated in patient samples that scleroderma upregulated transcription factor JUN and increased promoter accessibilities of both JUN and CD47. Next, we established our scleroderma model, demonstrating that Jun mediated skin fibrosis through the hedgehog-dependent expansion of CD26+Sca1- fibroblasts in mice. In a niche-independent adaptive transfer model, JUN steered graft survival and conferred increased self-renewal to fibroblasts. In vivo, JUN enhanced the expression of CD47, and inhibiting CD47 eliminated an ectopic fibroblast graft and increased in vitro phagocytosis. In the syngeneic mouse, depleting macrophages ameliorated skin fibrosis. Therapeutically, combined CD47 and IL-6 blockade reversed skin fibrosis in mice and led to the rapid elimination of ectopically transplanted scleroderma cells. Altogether, our study demonstrates the efficiency of combining different immunotherapies in treating scleroderma and provides a rationale for combining CD47 and IL-6 inhibition in clinical trials.

    View details for DOI 10.1172/jci.insight.140458

    View details for PubMedID 32814713

  • Survival of infants ≤24 months of age with brain tumors: Apopulation-based study using the SEER database. PloS one Faltermeier, C., Chai, T., Syed, S., Lau, N., Elkaim, L., Ibrahim, G., Wang, A., Weil, A., Bendel, A., Fallah, A., Tu, A. 2019; 14 (9): e0223051

    Abstract

    INTRODUCTION: Brain tumors are the most common solid malignancy and leading cause of cancer-related deaths in infants. Current epidemiological data is limited by low numbers of reported cases. This study used a population-based approach with analysis of contemporary and historical survival curves to provide up-to-date prognostication.METHODS: Observational cohort analysis was performed using the Surveillance, Epidemiology and End Results (SEER) database. Infants with brain tumors diagnosed from 1973 to 2013 were categorized by the most common tumor types (diffuse astrocytic and oligodendroglioma, choroid plexus, embryonal, ependymal, medulloblastoma and pilocytic astrocytoma). The 1, 5 and 10 year survival was stratified by decade, with trends in management and outcomes analyzed.RESULTS: We identified 2996 affected infants satisfying inclusion criteria. All tumor types, except embryonal and choroid plexus, demonstrated improving survival with time. Infants with embryonal tumors showed a decline in survival from the 1970s to 1990s (p = 0.009), whereas infants with choroid plexus tumors had no change in survival. Infants with ependymal tumors experienced the greatest improvement in survival from 1980s to 1990s and 1990s to 2000s (p = 0.0001, p = 0.01), with 5-year survival probability improving from 28% (95% CI 15-42%) in the 1980s to 77% (95% CI 69-83%) the 2000s. The use of radiation declined from 1970 to 2000 for all tumors; however, radiation treatment for embryonal and ependymal subtypes increased after 2000.CONCLUSIONS: While overall survival for infants with brain tumors has improved from the 1970s onwards, not every tumor type has seen a statistically significant change. Given changes in management and survival, prognostication of infants with brain tumor should be updated.

    View details for DOI 10.1371/journal.pone.0223051

    View details for PubMedID 31553771

  • Systemic surfaceome profiling identifies target antigens for immune-based therapy in subtypes of advanced prostate cancer PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Lee, J. K., Bangayan, N. J., Chai, T., Smith, B. A., Pariva, T. E., Yun, S., Vashisht, A., Zhang, Q., Park, J., Corey, E., Huang, J., Graeber, T. G., Wohlschlegel, J., Witte, O. N. 2018; 115 (19): E4473–E4482

    Abstract

    Prostate cancer is a heterogeneous disease composed of divergent molecular and histologic subtypes, including prostate adenocarcinoma (PrAd) and neuroendocrine prostate cancer (NEPC). While PrAd is the major histology in prostate cancer, NEPC can evolve from PrAd as a mechanism of treatment resistance that involves a transition from an epithelial to a neurosecretory cancer phenotype. Cell surface markers are often associated with specific cell lineages and differentiation states in normal development and cancer. Here, we show that PrAd and NEPC can be broadly discriminated by cell-surface profiles based on the analysis of prostate cancer gene expression datasets. To overcome a dependence on predictions of human cell-surface genes and an assumed correlation between mRNA levels and protein expression, we integrated transcriptomic and cell-surface proteomic data generated from a panel of prostate cancer cell lines to nominate cell-surface markers associated with these cancer subtypes. FXYD3 and CEACAM5 were validated as cell-surface antigens enriched in PrAd and NEPC, respectively. Given the lack of effective treatments for NEPC, CEACAM5 appeared to be a promising target for cell-based immunotherapy. As a proof of concept, engineered chimeric antigen receptor T cells targeting CEACAM5 induced antigen-specific cytotoxicity in NEPC cell lines. Our findings demonstrate that the surfaceomes of PrAd and NEPC reflect unique cancer differentiation states and broadly represent vulnerabilities amenable to therapeutic targeting.

    View details for PubMedID 29686080