The structure of intestinal tissue is complex. In vitro simulation of intestinal structure and function is important for studying intestinal development and diseases. Recently, organoids have been successfully constructed and they have come to play an important role in biomedical research. Organoids are miniaturized three-dimensional (3D) organs, derived from stem cells, which mimic the structure, cell types, and physiological functions of an organ, making them robust models for biomedical research. Intestinal organoids are 3D micro-organs derived from intestinal stem cells or pluripotent stem cells that can successfully simulate the complex structure and function of the intestine, thereby providing a valuable platform for intestinal development and disease research. In this article, we review the latest progress in the construction and application of intestinal organoids.
Organoids/cytology* ; Intestines/physiology* ; Humans ; Animals ; Pluripotent Stem Cells

Organoids are three-dimensional (3D) cellular structures formed through the differentiation and self-organization of pluripotent stem cells or tissue-derived cells, showing considerable potential in the research on disease mechanism, personalized medicine, and developmental biology. However, the development of organoids is limited by the complex composition, batch-to-batch variations, and immunogenicity of basement-membrane matrix in the current culture system, which hinders the clinical translation and in vivo applications of organoids. Hydrogels are highly hydrated 3D polymer network materials, with modifiable mechanical and biochemical properties by engineering, representing an ideal alternative to basement-membrane matrix. This article reviews the research progress in engineered hydrogels with defined composition currently used in organoid culture. We introduce the structural characteristics and engineering design considerations of hydrogels, emphasize the latest research progress and specific application cases, and discuss the future development of these engineered hydrogels, provide valuable insights for the further advancement and optimization of engineered hydrogels for organoid.
Hydrogels/chemistry* ; Organoids/cytology* ; Tissue Engineering/methods* ; Humans ; Animals ; Pluripotent Stem Cells/cytology* ; Cell Culture Techniques, Three Dimensional/methods* ; Tissue Scaffolds

METHODS: Cardiac organoids derived from the self-assembled human induced pluripotent stem cells were constructed by regulating the Wnt signaling pathway. Flow cytometry was used to detect the proportion of cardiomyocytes in the cardiac organoids, and RT-qPCR was employed to detect the mRNA expressions. Immunofluorescence staining was used to detect the protein expressions of TNNT2, CD31, and vimentin. The beating amplitude of the cardiac organoids was determined with calcium transient. In vitro myocardial injury models and ischemia-reperfusion models were established, and the cell injuries were examined using Masson staining. TUNEL staining and calcium transient detection were used to evaluate the adverse effects of doxorubicin and trastuzumab in the cardiac organoids. RESULTS: The cardiac organoids began to beat on the 8th day of culture and consisted of 32.4% cardiomyocytes with high expressions of the myocardial markers TNNT2, NKX2.5, RYR2 and KCNJ2. No significant differences in morphological size, beating frequency, proportion of cardiomyocytes, or myocardial contractility were observed in the cardiac organoids differentiated from different batches. These cardiac organoids could be maintained in in vitro culture conditions for at least 50 days. Captopril treatment could obviously alleviate liquid nitrogen-induced myocardial injury in the cardiac organoids. Hypoxia/reoxygenation induced ischemia-reperfusion injury and promoted myocardial fibrosis and apoptosis in the cardiac organoids. Treatment with doxorubicin for 24 h resulted in significantly increased cell death and reduced beating frequency and cell viability in the cardiac organoids in a dose-dependent manner. Trastuzumab significantly impaired the contractile and calcium handling abilities of the cardiac organoids. CONCLUSIONS Cardiac organoids derived from human induced pluripotent stem cells have been successfully constructed and can be used for cardiac disease modeling and drug evaluation.
Humans ; Induced Pluripotent Stem Cells/cytology* ; Organoids/cytology* ; Myocytes, Cardiac/cytology* ; Cell Differentiation ; Heart Diseases

Tissue formation and organ homeostasis are achieved by precise coordination of proliferation and differentiation of stem cells and progenitors. While deregulation of these processes can result in degenerative disease or cancer, their molecular interplays remain unclear. Here we show that the switch of human pluripotent stem cell (hPSC) self-renewal to differentiation is associated with the induction of distinct cyclin-dependent kinase inhibitors (CDKIs). In hPSCs, Activin/Nodal/TGFβ signaling maintains CDKIs in a poised state via SMAD2/3-NANOG-OCT4-EZH2-SNON transcriptional complex. Upon gradual differentiation, CDKIs are induced by successive transcriptional complexes between SMAD2/3-SMYD2 and developmental regulators such as EOMES, thereby lengthening the G1 phase. This, in turn, induces SMAD2/3 transcriptional activity by blocking its linker phosphorylation. Such SMAD2/3-CDKI positive feedback loops drive the exit from pluripotency and stepwise cell-fate specification that could be harnessed for producing cells for therapeutic applications. Our study uncovers fundamental mechanisms of how cell-fate specification is interconnected to cell-cycle dynamics and provides insight into autonomous circuitries governing tissue self-formation.
Humans ; Smad2 Protein/genetics* ; Smad3 Protein/genetics* ; Cell Differentiation ; Pluripotent Stem Cells/metabolism* ; Signal Transduction ; Octamer Transcription Factor-3/genetics* ; Enhancer of Zeste Homolog 2 Protein/genetics* ; Nanog Homeobox Protein/genetics* ; Phosphorylation

Frostbite is the most common cold injury and is caused by both immediate cold-induced cell death and the gradual development of localized inflammation and tissue ischemia. Delayed healing of frostbite often leads to scar formation, which not only causes psychological distress but also tends to result in the development of secondary malignant tumors. Therefore, a rapid healing method for frostbite wounds is urgently needed. Herein, we used a mouse skin model of frostbite injury to evaluate the recovery process after frostbite. Moreover, single-cell transcriptomics was used to determine the patterns of changes in monocytes, macrophages, epidermal cells, and fibroblasts during frostbite. Most importantly, human-induced pluripotent stem cell (hiPSC)-derived skin organoids combined with gelatin-hydrogel were constructed for the treatment of frostbite. The results showed that skin organoid treatment significantly accelerated wound healing by reducing early inflammation after frostbite and increasing the proportions of epidermal stem cells. Moreover, in the later stage of wound healing, skin organoids reduced the overall proportions of fibroblasts, significantly reduced fibroblast-to-myofibroblast transition by regulating the integrin α5β1-FAK pathway, and remodeled the extracellular matrix (ECM) through degradation and reassembly mechanisms, facilitating the restoration of physiological ECM and reducing the abundance of ECM associated with abnormal scar formation. These results highlight the potential application of organoids for promoting the reversal of frostbite-related injury and the recovery of skin functions. This study provides a new therapeutic alternative for patients suffering from disfigurement and skin dysfunction caused by frostbite.
Animals ; Organoids/metabolism* ; Mice ; Humans ; Wound Healing ; Frostbite/metabolism* ; Skin/pathology* ; Induced Pluripotent Stem Cells/cytology* ; Cicatrix/pathology* ; Fibroblasts/metabolism* ; Disease Models, Animal ; Mice, Inbred C57BL ; Extracellular Matrix/metabolism* ; Male

Human naïve pluripotent stem cells (PSCs) hold great promise for embryonic development studies. Existing induction and culture strategies for these cells, heavily dependent on MEK inhibitors, lead to widespread DNA hypomethylation, aberrant imprinting loss, and genomic instability during extended culture. Here, employing high-content analysis alongside a bifluorescence reporter system indicative of human naïve pluripotency, we screened over 1,600 chemicals and identified seven promising candidates. From these, we developed four optimized media-LAY, LADY, LUDY, and LKPY-that effectively induce and sustain PSCs in the naïve state. Notably, cells reset or cultured in these media, especially in the LAY system, demonstrate improved genome-wide DNA methylation status closely resembling that of pre-implantation counterparts, with partially restored imprinting and significantly enhanced genomic stability. Overall, our study contributes advancements to naïve pluripotency induction and long-term maintenance, providing insights for further applications of naïve PSCs.
Humans ; DNA Methylation/drug effects* ; Genomic Instability ; Pluripotent Stem Cells/metabolism* ; Cell Culture Techniques/methods* ; Cells, Cultured

In multiple areas such as science, technology, and economic activities, it is necessary to unify the management of repetitive tasks or concepts by standardization to obtain the best order and high efficiency. Organoids, as living tissue models, have rapidly developed in the past decade. Organoids can be used repetitively for in vitro culture, cryopreservation, and recovery for further utilization. Because organoids can recapitulate the parental tissues' morphological phenotypes, cell functions, biological behaviors, and genomic profiles, they are known as renewable "living biobanks". Organoids cover two mainstream fields: Adult stem cell-derived organoids (also known as patient-derived organoids) and induced pluripotent stem cell-derived and/or embryonic stem cell-derived organoids. Given the increasing importance of organoids in the development of new drugs, standardized operation, and management in all steps of organoid construction is an important guarantee to ensure the high quality of products. In this review, we systematically introduce the standardization of organoid construction operation procedures, the standardization of laboratory construction, and available standardization documents related to organoid culture that have been published so far. We also proposed the challenges and prospects in this field.
Organoids ; Humans ; Biological Specimen Banks/standards* ; Induced Pluripotent Stem Cells/cytology* ; Cryopreservation/methods*

Efforts have been made to establish various human pluripotent stem cell lines. However, such methods have not yet been duplicated in non-human primate cells. Here, we introduce a multiplexed single-cell sequencing technique to profile the molecular features of monkey pluripotent stem cells in published culture conditions. The results demonstrate suboptimized maintenance of pluripotency and show that the selected signaling pathways for resetting human stem cells can also be interpreted for establishing monkey cell lines. Overall, this work legitimates the translation of novel human cell line culture conditions to monkey cells and provides guidance for exploring chemical cocktails for monkey stem cell line derivation.
Animals ; Haplorhini ; Single-Cell Gene Expression Analysis ; Pluripotent Stem Cells/metabolism* ; Cell Line ; Signal Transduction ; Cell Differentiation ; Transcriptome

Although somatic cells can be reprogrammed to pluripotent stem cells (PSCs) with pure chemicals, authentic pluripotency of chemically induced pluripotent stem cells (CiPSCs) has never been achieved through tetraploid complementation assay. Spontaneous reprogramming of spermatogonial stem cells (SSCs) was another non-transgenic way to obtain PSCs, but this process lacks mechanistic explanation. Here, we reconstructed the trajectory of mouse SSC reprogramming and developed a five-chemical combination, boosting the reprogramming efficiency by nearly 80- to 100-folds. More importantly, chemical induced germline-derived PSCs (5C-gPSCs), but not gPSCs and chemical induced pluripotent stem cells, had authentic pluripotency, as determined by tetraploid complementation. Mechanistically, SSCs traversed through an inverted pathway of in vivo germ cell development, exhibiting the expression signatures and DNA methylation dynamics from spermatogonia to primordial germ cells and further to epiblasts. Besides, SSC-specific imprinting control regions switched from biallelic methylated states to monoallelic methylated states by imprinting demethylation and then re-methylation on one of the two alleles in 5C-gPSCs, which was apparently distinct with the imprinting reprogramming in vivo as DNA methylation simultaneously occurred on both alleles. Our work sheds light on the unique regulatory network underpinning SSC reprogramming, providing insights to understand generic mechanisms for cell-fate decision and epigenetic-related disorders in regenerative medicine.
Male ; Mice ; Animals ; Cellular Reprogramming/genetics* ; Tetraploidy ; Pluripotent Stem Cells/metabolism* ; Induced Pluripotent Stem Cells/metabolism* ; DNA Methylation ; Spermatogonia/metabolism* ; Germ Cells/metabolism*

Human pluripotent stem cells provide an inexhaustible model to study human embryogenesis in vitro. Recent studies have provided diverse models to generate human blastoids by self-organization of different pluripotent stem cells or somatic reprogramming intermediates. However, whether blastoids can be generated from other cell types or whether they can recapitulate postimplantation development in vitro is unknown. Here, we develop a strategy to generate human blastoids from heterogeneous intermediates with epiblast, trophectoderm, and primitive endoderm signatures of the primed-to-naïve conversion process, which resemble natural blastocysts in morphological architecture, composition of cell lineages, transcriptome, and lineage differentiation potential. In addition, these blastoids reflect many features of human peri-implantation and pregastrulation development when further cultured in an in vitro 3D culture system. In summary, our study provides an alternative strategy to generate human blastoids and offers insights into human early embryogenesis by modeling peri- and postimplantation development in vitro.
Humans ; Pluripotent Stem Cells/metabolism* ; Embryo, Mammalian/metabolism* ; Cell Differentiation ; Blastocyst ; Cell Lineage ; Embryonic Development