Anala Shetty

Was not provided for this article.

Liver transplantation remains the only definitive therapy for end stage liver disease, yet its application is fundamentally constrained by donor organ scarcity. Despite advances in organ preservation, marginal graft utilization, and xenotransplantation, a scalable source of functional liver tissue has not been realized. Blastocyst complementation has emerged as a novel strategy to generate exogenic organs, enabling the development of human derived hepatocytes within a xenogeneic host. The approach introduces a distinct biological paradigm where human parenchymal cells coexist with partial xenogeneic non-parenchymal compartments, resulting in compartmentalized immunogenicity. Efficient human-porcine blastocyst complementation remains an evolving technology, and functional exogenic humanized livers have yet to be demonstrated in large-animal transplant models. We examine exogenic liver transplantation through an immunology-first, clinical framework with emphasis on early graft injury driven predominantly by innate immune mechanisms at the vascular interface, including complement activation, macrophage mediated clearance, thrombocytopenia, and coagulation dysregulation as a major barrier observed in liver xenotransplantation. While adaptive immune responses may be attenuated due to reduced antigenic burden, residual xenogeneic endothelial and stromal compartments remain critical drivers of immune activation. We highlight exogenic hepatocyte transplantation as a potential translational bridge, enabling functional validation of chimerism-derived human hepatocytes in vivo while bypassing the vascular incompatibility inherent to whole organ transplantation. This cell-based therapy could offer a platform before the clinical realization of whole exogenic liver transplantation. We propose a phased immunomodulatory approach centered on early control of innate and humoral injury using induction therapy, plasmapheresis, and complement modulation, followed by tolerance-oriented tapering of maintenance immunosuppression. Finally, we outline a translational pathway incorporating preclinical validation, ex vivo perfusion, and human decedent transplant models, while addressing ethical, biosafety, and logistical considerations. Exogenic liver transplantation has the potential to represent a transformative strategy to generate scalable, immunologically optimized grafts and redefine the future of liver transplantation.

Introduction: Xenotransplantation has advanced through porcine genetic modifications to enhance graft survival and immunological compatibility. More recently, generating of exogenic organs from recipient-derived stem cells via blastocyst complementation has emerged as a promising strategy to achieve graft-specific tolerance and reduce dependence on long-term immunosuppression. However, ischemia-reperfusion-injury (IRI) during organ donation and transplantation activates inflammatory and innate immune pathways that compromise graft function and survival. To better understand the immunological response following interspecies transplantation, we compared xeno-adaptive and acute inflammatory responses between mouse-to-rat heterotopic liver transplants and rat allotransplants. This model will serve as baseline parameters for future studies of anti-inflammatory mechanisms to mitigate IRI, especially while testing exogenic livers. Methods: Livers from retired breeder male C57BL/6 mice were heterotopically transplanted into retired breeder male Lewis rats. After 90 minutes of reperfusion, transplanted liver, recipient blood and spleen were recovered for immune and inflammatory analyses. As a control to xenografts, Sprague Dawley donor livers were transplanted into Lewis recipients to represent a clinically relevant allotransplant model. Plasma cytokine and chemokine levels were quantified, and mixed leukocyte reactions (MLR) were performed to assess CD4⁺ and CD8⁺ T cell proliferation. Results: Xenografts exhibited elevated plasma levels of IL-2 (p = 0.04), IL-10 (p < 0.01), IL-13 (p = 0.01), IL-17A (p < 0.01) TNF-a (p < 0.05), and RANTES (p < 0.05) compared with naïve controls. Although xenografts demonstrated higher levels after transplant, they were not statistically distinct to allotransplant results. MLR assays revealed significantly increased CD8⁺ T cell proliferation (p = 0.01) when rat splenocytes were stimulated with mouse non-parenchymal liver cells, whereas CD4⁺ T cell proliferation was not significant in either model. Discussion: Although xenograft induced heightened inflammatory and adaptive responses, these were comparable to allotransplants. For successful exogenic organ transplantation without maintenance immunosuppression, future strategies must focus on mitigating reperfusion-induced systemic inflammation to improve graft tolerance and survival.

Incidence of neurodegenerative diseases such as Alzheimer’s, Parkinson’s, Huntington’s, and amyotrophic lateral sclerosis have increased dramatically as life expectancy has risen year-over-year, and can lead to neurologic changes. Neurological changes within the central nervous system, specifically the brain, include cell loss and deterioration that impact motor function, memory, executive function, and mood. Available treatments are limited and often only address symptomatic manifestations of the disease rather than disease progression. Cell transplantation therapy has shown promise for treating neurodegenerative diseases, but a source of autologous cells is required. Blastocyst complementation provides an innovative method for generating autologous neural cells. By injecting mouse induced pluripotent stem cells into a wild type mouse blastocyst, we generated a chimeric mouse brain derived of both donor and host neuronal and non-neuronal cells. At embryonic day 12.5 (E12.5), automated image analysis of mouse-mouse chimeric brains showed the presence of GFP-labeled donor-derived dopaminergic and serotonergic neuronal precursors. GFP-labeled donor-derived cholinergic precursor neurons and non-neuronal microglia-like and macrophage-like cells were also observed using more conventional imaging analysis software. This work demonstrates that the generation of mouse-mouse chimeric neural cells is possible; and that characterization of early neuronal and non-neuronal precursors provides a first step toward utilizing these cells for cell transplantation therapies for neurodegenerative diseases.

Coronavirus disease 2019 (COVID-19) in adults is well characterized and associated with multisystem dysfunction. A subset of patients develop post-acute sequelae of SARS-CoV-2 infection (PASC, or long COVID), marked by persistent and fluctuating organ system abnormalities. In children, distinct clinical and pathophysiological features of COVID-19 and long COVID are increasingly recognized, though knowledge remains limited relative to adults. The exponential expansion of the COVID-19 literature has made comprehensive appraisal by individual researchers increasingly unfeasible, highlighting the need for new approaches to evidence synthesis. Large language models (LLMs) such as the Generative Pre-trained Transformer (GPT) can process vast amounts of text, offering potential utility in this domain. Earlier versions of GPT, however, have been prone to generating fabricated references or misrepresentations of primary data. To evaluate the potential of more advanced models, we systematically applied GPT-4 to summarize studies on pediatric long COVID published between January 2022 and January 2025. Articles were identified in PubMed, and full-text PDFs were retrieved from publishers. GPT-4-generated summaries were cross-checked against the results sections of the original reports to ensure accuracy before incorporation into a structured review framework. This methodology demonstrates how LLMs may augment traditional literature review by improving efficiency and coverage in rapidly evolving fields, provided that outputs are subjected to rigorous human verification.

Analysis of a cell’s replication timing (RT) provides insight into how genes replicate, early or late, during the S-phase of the cell cycle. RT is cell-type specific, inheritable, and has been correlated to gene expression in normal and diseased states. However, most studies have been limited to somatic cells. Very little is known about RT control in early mouse embryos, and how it correlates with the start of transcription during zygote gene activation (ZGA), at the 2-cell stage. In this study, we develop an in-house single-cell multiomics approach to simultaneously analyze RT and gene expression in individual cells of the mouse 1-cell, 2-cell, and 4-cell embryos. We detect that RT is established at the 1-cell stage prior to ZGA. Surprisingly, we observe that the coordinated RT and gene expression control is different in early totipotent embryos, compared to previously published studies in somatic cells. Late replicating regions correlate with higher gene expression and open chromatin in the early developing embryos. Lastly, we perform an integrated pseudo time trajectory analysis combining RT and gene expression information per cell.

While prime editing offers improved precision compared to traditional CRISPR-Cas9 systems, concerns remain regarding potential off-target effects, including epigenetic changes such as DNA methylation. In this study, we investigated whether prime editing induces aberrant CpG methylation patterns. Whole-genome bisulfite sequencing revealed overall methylation similarity between Cas9-edited, and PE2-edited cells. However, localized epigenetic changes were observed, particularly in CpG islands and exon regions. The PE2-edited group showed a higher proportion of differentially methylated regions (DMRs) in some coding sequences compared to controls and Cas9-edited samples. Notably, CpG island methylation reached 0.18% in the PE2 vs. Cas9 comparison, indicating a higher susceptibility of these regulatory elements to epigenetic alterations by prime editing. Molecular function analyses including Gene Ontology and KEGG pathway analyses further revealed enrichment in molecular functions related to transcriptional regulation and redox activity in PE2-edited cells. These findings suggest that prime editing, while precise, may introduce subtle but functionally relevant methylation changes that could influence gene expression and cellular pathways. In summary, prime editing can induce localized DNA methylation changes in human cells, particularly within regulatory and coding regions. Understanding these epigenetic consequences is critical for the development of safer and more effective therapeutic applications of genome editing technologies.

Incidence of neurodegenerative diseases such as Alzheimer’s, Parkinson’s, Huntington’s, and amyotrophic lateral sclerosis have increased dramatically as life expectancy at birth has risen year-over-year and the population ages. Neurological changes within the central nervous system, specifically the brain, include cell loss and deterioration that impact motor function, memory, executive function, and mood. Available treatments are limited and often only address symptomatic manifestations of the disease rather than disease progression. Cell transplantation therapy has shown promise for treating neurodegenerative diseases, but a source of autologous cells is required. Blastocyst complementation provides an innovative method for generating those autologous neural cells. By injecting mouse induced pluripotent stem cells (iPSCs) into a wild type (WT) mouse blastocyst, we generated a chimeric mouse brain derived of both donor and host neuronal and non-neuronal cells. An embryonic day 12.5 (E12.5), automated image analysis of mouse-mouse chimeric brains showed the presence of GFP-labeled donor-derived dopaminergic and serotonergic neuronal precursors. GFP-labeled donor-derived cholinergic precursor neurons and non-neuronal microglia-like and macrophage-like cells were also observed using more conventional imaging analysis software. This work demonstrates that the generation of mouse-mouse chimeric neural cells is possible; and that characterization of early neuronal and non-neuronal precursors provides a first step towards utilizing these cells for cell transplantation therapies for neurodegenerative diseases.

Solid organ transplantation remains a life-saving treatment for patients worldwide. Unfortunately, the supply of donor organs cannot meet the current need, making the search for alternative sources even more essential. Xenotransplantation using sophisticated genetic engineering techniques to delete and overexpress specific genes in the donor animal has been investigated as a possible option. However, the use of exogenous tissue presents another host of obstacles, particularly regarding organ rejection. Given these limitations, interspecies blastocyst complementation in combination with precise gene knockouts presents a unique, promising pathway for the transplant organ shortage. In recent years, great advancements have been made in the field, with encouraging results in producing a donor-derived organ in a chimeric host. That said, one of the major barriers to successful interspecies chimerism is the mismatch in the developmental stages of the donor and the host cells in the chimeric embryo. Another major barrier to successful chimerism is the mismatch in the developmental speeds between the donor and host cells in the chimeric embryos. This review outlines 19 studies in which blastocyst complementation was used to generate solid organs. In particular, the genesis of the liver, lung, kidney, pancreas, heart, thyroid, thymus and parathyroids was investigated. Of the 19 studies, 7 included an interspecies model. Of the 7, one was completed using human donor cells in a pig host, and all others were rat–mouse chimeras. While very promising results have been demonstrated, with great advancements in the field, several challenges continue to persist. In particular, successful chimerism, organ generation and donor contribution, synchronized donor–host development, as well as ethical concerns regarding human–animal chimeras remain important aspects that will need to be addressed in future research.