Project description:Millions suffer from incurable lung diseases, and the donor lung shortage hampers organ transplants. Generating the whole organ in conjunction with the thymus is a significant milestone for organ transplantation because the thymus is the central organ to educate immune cells. Using lineage-tracing mice and human pluripotent stem cell (PSC)-derived lung-directed differentiation, we revealed that gastrulating Foxa2 lineage contributed to both lung mesenchyme and epithelium formation. Interestingly, Foxa2 lineage-derived cells in the lung mesenchyme progressively increased and occupied more than half of the mesenchyme niche, including endothelial cells, during lung development. Foxa2 promoter-driven, conditional Fgfr2 gene depletion caused the lung and thymus agenesis phenotype in mice. Wild-type donor mouse PSCs injected into their blastocysts rescued this phenotype by complementing the Fgfr2-defective niche in the lung epithelium and mesenchyme and thymic epithelium. Donor cell is shown to replace the entire lung epithelial and robust mesenchymal niche during lung development, efficiently complementing the nearly entire lung niche. Importantly, those mice survived until adulthood with normal lung function. These results suggest that our Foxa2 lineage-based model is unique for the progressive mobilization of donor cells into both epithelial and mesenchymal lung niches and thymus generation, which can provide critical insights into studying lung transplantation post-transplantation shortly.
Project description:Rationale: The regeneration and replacement of lung cells or tissues from induced pluripotent stem cell- or embryonic stem cell-derived cells represent future therapies for life-threatening pulmonary disorders but are limited by technical challenges to produce highly differentiated cells able to maintain lung function. Functional lung tissue-containing airways, alveoli, vasculature, and stroma have never been produced via directed differentiation of embryonic stem cells (ESCs) or induced pluripotent stem cells. We sought to produce all tissue components of the lung from bronchi to alveoli by embryo complementation.Objectives: To determine whether ESCs are capable of generating lung tissue in Nkx2-1-/- mouse embryos with lung agenesis.Methods: Blastocyst complementation was used to produce chimeras from normal mouse ESCs and Nkx2-1-/- embryos, which lack pulmonary tissues. Nkx2-1-/- chimeras were examined using immunostaining, transmission electronic microscopy, fluorescence-activated cell sorter analysis, and single-cell RNA sequencing.Measurements and Main Results: Although peripheral pulmonary and thyroid tissues are entirely lacking in Nkx2-1 gene-deleted embryos, pulmonary and thyroid structures in Nkx2-1-/- chimeras were restored after ESC complementation. Respiratory epithelial cell lineages in restored lungs of Nkx2-1-/- chimeras were derived almost entirely from ESCs, whereas endothelial, immune, and stromal cells were mosaic. ESC-derived cells from multiple respiratory cell lineages were highly differentiated and indistinguishable from endogenous cells based on morphology, ultrastructure, gene expression signatures, and cell surface proteins used to identify cell types by fluorescence-activated cell sorter.Conclusions: Lung and thyroid tissues were generated in vivo from ESCs by blastocyst complementation. Nkx2-1-/- chimeras can be used as "bioreactors" for in vivo differentiation and functional studies of ESC-derived progenitor cells.
Project description:In the case of organ transplantation accompanied by vascular anastomosis, major histocompatibility complex mismatched vascular endothelial cells become a target for graft rejection. Production of a rejection-free, transplantable organ, therefore, requires simultaneous generation of vascular endothelial cells within the organ. To generate pluripotent stem cell (PSC)-derived vascular endothelial cells, we performed blastocyst complementation with a vascular endothelial growth factor receptor-2 homozygous mutant blastocyst. This mutation is embryonic lethal at embryonic (E) day 8.5-9.5 due to an early defect in endothelial and hematopoietic cells. The Flk-1 homozygous knockout chimeric mice survived to adulthood for over 1 year without any abnormality, and all vascular endothelial cells and hematopoietic cells were derived from the injected PSCs. This approach could be used in conjunction with other gene knockouts which induce organ deficiency to produce a rejection-free, transplantable organ in which all the organ's cells and vasculature are PSC derived.
Project description:Millions of people worldwide with incurable end-stage lung disease die because of inadequate treatment options and limited availability of donor organs for lung transplantation1. Current bioengineering strategies to regenerate the lung have not been able to replicate its extraordinary cellular diversity and complex three-dimensional arrangement, which are indispensable for life-sustaining gas exchange2,3. Here we report the successful generation of functional lungs in mice through a conditional blastocyst complementation (CBC) approach that vacates a specific niche in chimeric hosts and allows for initiation of organogenesis by donor mouse pluripotent stem cells (PSCs). We show that wild-type donor PSCs rescued lung formation in genetically defective recipient mouse embryos unable to specify (due to Ctnnb1cnull mutation) or expand (due to Fgfr2cnull mutation) early respiratory endodermal progenitors. Rescued neonates survived into adulthood and had lungs functionally indistinguishable from those of wild-type littermates. Efficient chimera formation and lung complementation required newly developed culture conditions that maintained the developmental potential of the donor PSCs and were associated with global DNA hypomethylation and increased H4 histone acetylation. These results pave the way for the development of new strategies for generating lungs in large animals to enable modeling of human lung disease as well as cell-based therapeutic interventions4-6.
Project description:Generation of functional organs from patients' own cells is one of the ultimate goals of regenerative medicine. As a novel approach to creation of organs from pluripotent stem cells (PSCs), we employed blastocyst complementation in organogenesis-disabled animals and successfully generated PSC-derived pancreas and kidneys. Blastocyst complementation, which exploits the capacity of PSCs to participate in forming chimeras, does not, however, exclude contribution of PSCs to the development of tissues-including neural cells or germ cells-other than those specifically targeted by disabling of organogenesis. This fact provokes ethical controversy if human PSCs are to be used. In this study, we demonstrated that forced expression of Mix-like protein 1 (encoded by Mixl1) can be used to guide contribution of mouse embryonic stem cells to endodermal organs after blastocyst injection. We then succeeded in applying this method to generate functional pancreas in pancreatogenesis-disabled Pdx1 knockout mice using a newly developed tetraploid-based organ-complementation method. These findings hold promise for targeted organ generation from patients' own PSCs in livestock animals.
Project description:Genetically modified mice are commonly generated by the microinjection of pluripotent embryonic stem (ES) cells into wild-type host blastocysts1, producing chimeric progeny that require breeding for germline transmission and homozygosity of modified alleles. As an alternative approach and to facilitate studies of the immune system, we previously developed RAG2-deficient blastocyst complementation2. Because RAG2-deficient mice cannot undergo V(D)J recombination, they do not develop B or T lineage cells beyond the progenitor stage2: injecting RAG2-sufficient donor ES cells into RAG2-deficient blastocysts generates somatic chimaeras in which all mature lymphocytes derive from donor ES cells. This enables analysis, in mature lymphocytes, of the functions of genes that are required more generally for mouse development3. Blastocyst complementation has been extended to pancreas organogenesis4, and used to generate several other tissues or organs5-10, but an equivalent approach for brain organogenesis has not yet been achieved. Here we describe neural blastocyst complementation (NBC), which can be used to study the development and function of specific forebrain regions. NBC involves targeted ablation, mediated by diphtheria toxin subunit A, of host-derived dorsal telencephalic progenitors during development. This ablation creates a vacant forebrain niche in host embryos that results in agenesis of the cerebral cortex and hippocampus. Injection of donor ES cells into blastocysts with forebrain-specific targeting of diphtheria toxin subunit A enables donor-derived dorsal telencephalic progenitors to populate the vacant niche in the host embryos, giving rise to neocortices and hippocampi that are morphologically and neurologically normal with respect to learning and memory formation. Moreover, doublecortin-deficient ES cells-generated via a CRISPR-Cas9 approach-produced NBC chimaeras that faithfully recapitulated the phenotype of conventional, germline doublecortin-deficient mice. We conclude that NBC is a rapid and efficient approach to generate complex mouse models for studying forebrain functions; this approach could more broadly facilitate organogenesis based on blastocyst complementation.
Project description:This research is the first to produce induced pluripotent stem cell-derived inner ear sensory neurons in the Neurog1+/- heterozygote mouse using blastocyst complementation. Additionally, this approach corrected non-sensory deficits associated with Neurog1 heterozygosity, indicating that complementation is specific to endogenous Neurog1 function. This work validates the use of blastocyst complementation as a tool to create novel insight into the function of developmental genes and highlights blastocyst complementation as a potential platform for generating chimeric inner ear cell types that can be transplanted into damaged inner ears to improve hearing.
Project description:The generation of mature, functional, thyroid follicular cells from pluripotent stem cells would potentially provide a therapeutic benefit for patients with hypothyroidism, but in vitro differentiation remains difficult. We earlier reported the in vivo generation of lung organs via blastocyst complementation in fibroblast growth factor 10 (Fgf10), compound, heterozygous mutant (Fgf10 Ex1mut/Ex3mut) mice. Fgf10 also plays an essential role in thyroid development and branching morphogenesis, but any role thereof in thyroid organogenesis remains unclear. Here, we report that the thyroids of Fgf10 Ex1mut/Ex3mut mice exhibit severe hypoplasia, and we generate thyroid tissues from mouse embryonic stem cells (ESCs) in Fgf10 Ex1mut/Ex3mut mice via blastocyst complementation. The tissues were morphologically normal and physiologically functional. The thyroid follicular cells of Fgf10 Ex1mut/Ex3mut chimeric mice were derived largely from GFP-positive mouse ESCs although the recipient cells were mixed. Thyroid generation in vivo via blastocyst complementation will aid functional thyroid regeneration.
Project description:The application of pluripotent stem cells is expected to contribute to the elucidation of unknown mechanism of human diseases. However, in vitro induction of organ-specific cells, such as pancreas and liver, is still difficult and the reproduction of their disorders in a model has been unfeasible. To study the mechanism of human hereditary pancreatitis (HP), we here performed the blastocyst complementation (BC) method. In the BC method, mouse embryonic stem (ES) cells harboring CRISPR/CAS9-mediated mutations in the Prss1 gene were injected into blastocysts with deficient Pdx1 gene, which is a critical transcription factor in the development of pancreas. The results showed that trypsin was activated extremely in Prss1-mutant mice. This implied that the mouse phenotype mimics that of human HP and that the BC method was useful for the reproduction and study of pancreatic disorders. The present study opens the possibility of investigating uncharacterized human diseases by utilizing the BC method.
Project description:Murine animal models from genetically modified pluripotent stem cells (PSCs) are essential for functional genomics and biomedical research, which require germline transmission for the establishment of colonies. However, the quality of PSCs, and donor-host cell competition in chimeras often present strong barriers for germline transmission. Here, we report efficient germline transmission of recalcitrant PSCs via blastocyst complementation, a method to compensate for missing tissues or organs in genetically modified animals via blastocyst injection of PSCs. We show that blastocysts from germline-deficient Prdm14 knockout rats provide a niche for the development of gametes originating entirely from the donor PSCs without any detriment to somatic development. We demonstrate the potential of this approach by creating PSC-derived Pax2/Pax8 double mutant anephric rats, and rescuing germline transmission of a PSC carrying a mouse artificial chromosome. Furthermore, we generate mouse PSC-derived functional spermatids in rats, which provides a proof-of-principle for the generation of xenogenic gametes in vivo. We believe this approach will become a useful system for generating PSC-derived germ cells in the future.