A tissue-bioengineering strategy for modeling rare human kidney diseases in vivo

Toxicological effects and mechanisms of renal injury induced by inhalation exposure to airborne nanoplastics

Micro-nanoplastics (MNPs) are ubiquitously present in various natural habitats, and the kidney plays a critical role in eliminating metabolic waste from the body. Therefore, nephrotoxicity studies of MNPs are necessary. Consequently, we conducted a study utilizing a mouse model that underwent autonomous inhalation of polystyrene nanoplastics (PS-NPs) to investigate the impact of airborne nanoplastics (NPs) on kidney. The results demonstrated that airborne NPs could accumulate within the kidney subsequent to pulmonary entry. Transcriptome analysis showed that exposure to airborne NPs persistently interfered with important signaling pathways including oxidative stress, inflammation, and coagulation, which activated the NR4A1/CASP3 and TF/F12 signaling pathways. In vitro studies have shown that NPs were internalized by human kidney proximal tubular epithelial (HK-2) cells, leading to a range of pathological responses, and ultimately affecting cell fate. Furthermore, we pioneered the exposure of NPs to human kidney organoids. Our findings revealed a heightened sensitivity in kidney organoids towards NPs as compared to immortalized cell lines. This suggested that exposure to NPs could potentially inflict a more substantial toxic effect on the development of embryonic kidneys. In conclusion, this study has revealed the deleterious effects of exposure to airborne NPs on the mouse kidney.

Biomedical applications of organoids in genetic diseases

Organoid technology has significantly transformed biomedical research by providing exceptional prospects for modeling human tissues and disorders in a laboratory setting. It has significant potential for understanding the intricate relationship between genetic mutations, cellular phenotypes, and disease pathology, especially in the field of genetic diseases. The intersection of organoid technology and genetic research offers great promise for comprehending the pathophysiology of genetic diseases and creating innovative treatment approaches customized for specific patients. This review aimed to present a thorough analysis of the current advancements in organoid technology and its biomedical applications for genetic diseases. We examined techniques for modeling genetic disorders using organoid platforms, analyze the approaches for incorporating genetic disease organoids into clinical practice, and showcase current breakthroughs in preclinical application, individualized healthcare, and transplantation. Through the integration of knowledge from several disciplines, such as genetics, regenerative medicine, and biological engineering, our aim is to enhance our comprehension of the complex connection between genetic variations and organoid models in relation to human health and disease.

Organoids from pluripotent stem cells and human tissues: When two cultures meet each other

Human organoids are a widely used tool in cell biology to study homeostatic processes, disease, and development. The term organoids covers a plethora of model systems from different cellular origins that each have unique features and applications but bring their own challenges. This review discusses the basic principles underlying organoids generated from pluripotent stem cells (PSCs) as well as those derived from tissue stem cells (TSCs). We consider how well PSC- and TSC-organoids mimic the different intended organs in terms of cellular complexity, maturity, functionality, and the ongoing efforts to constitute predictive complex models of in vivo situations. We discuss the advantages and limitations associated with each system to answer different biological questions including in the field of cancer and developmental biology, and with respect to implementing emerging advanced technologies, such as (spatial) -omics analyses, CRISPR screens, and high-content imaging screens. We postulate how the two fields may move forward together, integrating advantages of one to the other.

A systematic review on the culture methods and applications of 3D tumoroids for cancer research and personalized medicine

Cancer is a highly heterogeneous disease, and thus treatment responses vary greatly between patients. To improve therapy efficacy and outcome for cancer patients, more representative and patient-specific preclinical models are needed. Organoids and tumoroids are 3D cell culture models that typically retain the genetic and epigenetic characteristics, as well as the morphology, of their tissue of origin. Thus, they can be used to understand the underlying mechanisms of cancer initiation, progression, and metastasis in a more physiological setting. Additionally, co-culture methods of tumoroids and cancer-associated cells can help to understand the interplay between a tumor and its tumor microenvironment. In recent years, tumoroids have already helped to refine treatments and to identify new targets for cancer therapy. Advanced culturing systems such as chip-based fluidic devices and bioprinting methods in combination with tumoroids have been used for high-throughput applications for personalized medicine. Even though organoid and tumoroid models are complex in vitro systems, validation of results in vivo is still the common practice. Here, we describe how both animal- and human-derived tumoroids have helped to identify novel vulnerabilities for cancer treatment in recent years, and how they are currently used for precision medicine.

Organoids as Sophisticated Tools for Renal Cancer Research: Extensive Applications and Promising Prospects

Background

Kidney cancer is a significant global health problem that affects nearly 1 in 25 of cancer patients. Prevalence, morbidity and mortality data associated with kidney cancer continue to increase every year, revealing a heavy economic and social burden. Organoid culture is a new research tool with great potential for many applications, particularly in cancer research. The integration of organoids with other emerging technologies has simultaneously expanded their potential applications. However, there is no thorough assessment of organoids in the field of renal cancer research.

Objectives

This paper presents a comprehensive review of the current development of renal cancer organoids and discusses the corresponding solutions and future directions of renal cancer organoids.

Methods

In this study, we have compared the operating procedures of different organoid culture protocols and proposed a summary of constituents in culture media. Extensive discussions of renal cancer organoids, including generation and maintenance approaches, application scenarios, current challenges and prospects, have also been made. The information required for this study is extracted from literature databases such as PubMed, SCOPUS and Web of Science.

Results

In this article, we systematically review thirteen successful methods for generating organoids to kidney cancer and provide practical guidelines for their construction as a reference. In addition, we also elucidate the clinical application of organoids, address the existing challenges and limitations, and highlight promising prospects.

Conclusion

Ultimately, we firmly believe that as kidney tumour organoids continue to develop and improve, they will become a crucial tool for treating kidney cancer.

Augmented ERO1α upon mTORC1 activation induces ferroptosis resistance and tumor progression via upregulation of SLC7A11

BACKGROUND

The dysregulated mechanistic target of rapamycin complex 1 (mTORC1) signaling plays a critical role in ferroptosis resistance and tumorigenesis. However, the precise underlying mechanisms still need to be fully understood.

METHODS

Endoplasmic reticulum oxidoreductase 1 alpha (ERO1α) expression in mTORC1-activated mouse embryonic fibroblasts, cancer cells, and laryngeal squamous cell carcinoma (LSCC) clinical samples was examined by quantitative real-time PCR (qRT-PCR), western blotting, immunofluorescence (IF), and immunohistochemistry. Extensive in vitro and in vivo experiments were carried out to determine the role of ERO1α and its downstream target, member 11 of the solute carrier family 7 (SLC7A11), in mTORC1-mediated cell proliferation, angiogenesis, ferroptosis resistance, and tumor growth. The regulatory mechanism of ERO1α on SLC7A11 was investigated via RNA-sequencing, a cytokine array, an enzyme-linked immunosorbent assay, qRT-PCR, western blotting, IF, a luciferase reporter assay, and a chromatin immunoprecipitation assay. The combined therapeutic effect of ERO1α inhibition and the ferroptosis inducer imidazole ketone erastin (IKE) on mTORC1-activated cells was evaluated using cell line-derived xenografts, LSCC organoids, and LSCC patient-derived xenograft models.

RESULTS

ERO1α is a functional downstream target of mTORC1. Elevated ERO1α induced ferroptosis resistance and exerted pro-oncogenic roles in mTORC1-activated cells via upregulation of SLC7A11. Mechanically, ERO1α stimulated the transcription of SLC7A11 by activating the interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) pathway. Moreover, ERO1α inhibition combined with treatment using the ferroptosis inducer IKE exhibited synergistic antitumor effects on mTORC1-activated tumors.

CONCLUSIONS

The ERO1α/IL-6/STAT3/SLC7A11 pathway is crucial for mTORC1-mediated ferroptosis resistance and tumor growth, and combining ERO1α inhibition with ferroptosis inducers is a novel and effective treatment for mTORC1-related tumors.

Advancements in kidney organoids and tubuloids to study (dys)function

The rising prevalence of kidney diseases urges the need for novel therapies. Kidney organoids and tubuloids are advanced in vitro models and have recently been described as promising tools to study kidney (patho)physiology. Recent developments have shown their application in disease modeling, drug screening, and nephrotoxicity. These applications rely on their ability to mimic (dys)function in vitro including endocrine activity and drug, electrolyte, and water transport. This review provides an overview of these emerging kidney models and focuses on the most recent developments that utilize their functional capabilities. In addition, we cover current limitations and provide future perspectives for this rapidly evolving field, including what these functional properties mean for translational and personalized medicine now and in the future.

Modeling tuberous sclerosis complex with human induced pluripotent stem cells

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder with a birth incidence of 1:6000 in the United States that is characterized by the growth of non-cancerous tumors in multiple organ systems including the brain, kidneys, lungs, and skin. Importantly, TSC is also associated with significant neurological manifestations including epilepsy, TSC-associated neuropsychiatric disorders, intellectual disabilities, and autism spectrum disorder. Mutations in the TSC1 or TSC2 genes are well-established causes of TSC, which lead to TSC1/TSC2 deficiency in organs and hyper-activation of the mammalian target of rapamycin signaling pathway. Animal models have been widely used to study the effect of TSC1/2 genes on the development and function of the brain. Despite considerable progress in understanding the molecular mechanisms underlying TSC in animal models, a human-specific model is urgently needed to investigate the effects of TSC1/2 mutations that are unique to human neurodevelopment.

DATA SOURCES

Literature reviews and research articles were published in PubMed-indexed journals.

RESULTS

Human-induced pluripotent stem cells (iPSCs), which capture risk alleles that are identical to their donors and have the capacity to differentiate into virtually any cell type in the human body, pave the way for the empirical study of previously inaccessible biological systems such as the developing human brain.

CONCLUSIONS

In this review, we present an overview of the recent progress in modeling TSC with human iPSC models, the existing limitations, and potential directions for future research.

Engineered organoids for biomedical applications

As miniaturized and simplified stem cell-derived 3D organ-like structures, organoids are rapidly emerging as powerful tools for biomedical applications. With their potential for personalized therapeutic interventions and high-throughput drug screening, organoids have gained significant attention recently. In this review, we discuss the latest developments in engineering organoids and using materials engineering, biochemical modifications, and advanced manufacturing technologies to improve organoid culture and replicate vital anatomical structures and functions of human tissues. We then explore the diverse biomedical applications of organoids, including drug development and disease modeling, and highlight the tools and analytical techniques used to investigate organoids and their microenvironments. We also examine the latest clinical trials and patents related to organoids that show promise for future clinical translation. Finally, we discuss the challenges and future perspectives of using organoids to advance biomedical research and potentially transform personalized medicine.

Advances and challenges toward developing kidney organoids for clinical applications

Kidney organoids have enabled modeling of human development and disease. While methods of generating the nephron lineage are well established, new protocols to induce another lineage, the ureteric bud/collecting duct, have been reported in the past 5 years. Many reports have described modeling of various hereditary kidney diseases, with polycystic kidney disease serving as the archetypal disease, by using patient-derived or genome-edited kidney organoids. The generation of more organotypic kidneys is also becoming feasible. In this review, I also discuss the significant challenges for more sophisticated disease modeling and for realizing the ambitious goal of generating transplantable synthetic kidneys.

Cell Reprogramming Techniques: Contributions to Cancer Therapy

The reprogramming of terminally differentiated cells over the past few years has become important for induced pluripotent stem cells (iPSCs) in the field of regenerative medicine and disease drug modeling. At the same time, iPSCs have also played an important role in human cancer research. iPSCs derived from cancer patients can be used to simulate the early progression of cancer, for drug testing, and to study the molecular mechanism of cancer occurrence. In recent years, with the application of cellular immunotherapy in cancer therapy, patient-derived iPSC-induced immune cells (T, natural killer, and macrophage cells) solve the problem of immune rejection and have higher immunogenicity, which greatly improves the therapeutic efficiency of immune cell therapy. With the continuous progress of cancer differentiation therapy, iPSC technology can reprogram cancer cells to a more primitive pluripotent undifferentiated state, and successfully reverse cancer cells to a benign phenotype by changing the epigenetic inheritance of cancer cells. This article reviews the recent progress of cell reprogramming technology in human cancer research, focuses on the application of reprogramming technology in cancer immunotherapy and the problems solved, and summarizes the malignant phenotype changes of cancer cells in the process of reprogramming and subsequent differentiation.

Tuberous Sclerosis Complex Kidney Lesion Pathogenesis: A Developmental Perspective

The phenotypic diversity of tuberous sclerosis complex (TSC) kidney pathology is enigmatic. Despite a well-established monogenic etiology, an incomplete understanding of lesion pathogenesis persists. In this review, we explore the question: How do TSC kidney lesions arise? We appraise literature findings in the context of mutational timing and cell-of-origin. Through a developmental lens, we integrate the critical results from clinical studies, human specimens, and genetic animal models. We also review novel insights gleaned from emerging organoid and single-cell sequencing technologies. We present a new model of pathogenesis which posits a phenotypic continuum, whereby lesions arise by mutagenesis during development from variably timed second-hit events. This model can serve as a conceptual framework for testing hypotheses of TSC lesion pathogenesis, both in the kidney and in other affected tissues.

Arginine depletion attenuates renal cystogenesis in tuberous sclerosis complex model

Cystic kidney disease is a leading cause of morbidity in patients with tuberous sclerosis complex (TSC). We characterize the misregulated metabolic pathways using cell lines, a TSC mouse model, and human kidney sections. Our study reveals a substantial perturbation in the arginine biosynthesis pathway in TSC models with overexpression of argininosuccinate synthetase 1 (ASS1). The rise in ASS1 expression is dependent on the mechanistic target of rapamycin complex 1 (mTORC1) activity. Arginine depletion prevents mTORC1 hyperactivation and cell cycle progression and averts cystogenic signaling overexpression of c-Myc and P65. Accordingly, an arginine-depleted diet substantially reduces the TSC cystic load in mice, indicating the potential therapeutic effects of arginine deprivation for the treatment of TSC-associated kidney disease.

Human pluripotent-stem-cell-derived organoids for drug discovery and evaluation

Human pluripotent stem cells (hPSCs) and three-dimensional organoids have ushered in a new era for disease modeling and drug discovery. Over the past decade, significant progress has been in deriving functional organoids from hPSCs, which have been applied to recapitulate disease phenotypes. In addition, these advancements have extended the application of hPSCs and organoids for drug screening and clinical-trial safety evaluations. This review provides an overview of the achievements and challenges in using hPSC-derived organoids to conduct relevant high-throughput, high-contentscreens and drug evaluation. These studies have greatly enhanced our knowledge and toolbox for precision medicine.

Can Kidney Organoid Xenografts Accelerate Therapeutic Development for Genetic Kidney Disorders?

A number of genetic kidney diseases can now be replicated experimentally, using kidney organoids generated from human pluripotent stem cells. This methodology holds great potential for drug discovery. Under in vitro conditions, however, kidney organoids remain developmentally immature, develop scarce vasculature, and may contain undesired off-target cell types. Those critical deficiencies limit their potential as disease-modeling tools. Orthotopic transplantation under the kidney capsule improves the anatomic maturity and vascularization of kidney organoids, while reducing off-target cell content. The improvements can translate into more accurate representations of disease phenotypes and mechanisms in vivo . Recent studies using kidney organoid xenografts highlighted the unique potential of this novel methodology for elucidating molecular mechanisms driving monogenic kidney disorders and for the development ofnovel pharmacotherapies.

Production of kidney organoids arranged around single ureteric bud trees, and containing endogenous blood vessels, solely from embryonic stem cells

There is intense worldwide effort in generating kidney organoids from pluripotent stem cells, for research, for disease modelling and, perhaps, for making transplantable organs. Organoids generated from pluripotent stem cells (PSC) possess accurate micro-anatomy, but they lack higher-organization. This is a problem, especially for transplantation, as such organoids will not be able to perform their physiological functions. In this study, we develop a method for generating murine kidney organoids with improved higher-order structure, through stages using chimaeras of ex-fetu and PSC-derived cells to a system that works entirely from embryonic stem cells. These organoids have nephrons organised around a single ureteric bud tree and also make vessels, with the endothelial network approaching podocytes.

Disease Modeling with Kidney Organoids

Kidney diseases often lack optimal treatments, causing millions of deaths each year. Thus, developing appropriate model systems to study human kidney disease is of utmost importance. Some of the most promising human kidney models are organoids or small organ-resembling tissue collectives, derived from human-induced pluripotent stem cells (hiPSCs). However, they are more akin to a first-trimester fetal kidney than an adult kidney. Therefore, new strategies are needed to advance their maturity. They have great potential for disease modeling and eventually auxiliary therapy if they can reach the maturity of an adult kidney. In this review, we will discuss the current state of kidney organoids in terms of their similarity to the human kidney and use as a disease modeling system thus far. We will then discuss potential pathways to advance the maturity of kidney organoids to match an adult kidney for more accurate human disease modeling.

Renal organoid modeling of tuberous sclerosis complex reveals lesion features arise from diverse developmental processes

Tuberous sclerosis complex (TSC) is a multisystem tumor-forming disorder caused by loss of TSC1 or TSC2. Renal manifestations predominately include cysts and angiomyolipomas. Despite a well-described monogenic etiology, the cellular pathogenesis remains elusive. We report a genetically engineered human renal organoid model that recapitulates pleiotropic features of TSC kidney disease in vitro and upon orthotopic xenotransplantation. Time course single-cell RNA sequencing demonstrates that loss of TSC1 or TSC2 affects multiple developmental processes in the renal epithelial, stromal, and glial compartments. First, TSC1 or TSC2 ablation induces transitional upregulation of stromal-associated genes. Second, epithelial cells in the TSC1^-/- and TSC2^-/- organoids exhibit a rapamycin-insensitive epithelial-to-mesenchymal transition. Third, a melanocytic population forms exclusively in TSC1^-/- and TSC2^-/- organoids, branching from MITF⁺ Schwann cell precursors. Together, these results illustrate the pleiotropic developmental consequences of biallelic inactivation of TSC1 or TSC2 and offer insight into TSC kidney lesion pathogenesis.

In Situ Detection of Kidney Organoid Generation From Stem Cells Using a Simple Electrochemical Method

Organoids that mimic the structural and cellular characteristics of kidneys in vitro have recently emerged as a promising source for biomedical research. However, uncontrollable cellular heterogeneity after differentiation often results in the generation of off-target cells, one of the most challenging issues in organoid research. This study proposes a new method that enables the real-time assessment of kidney organoids derived from stem cells. When placed on a conductive surface, these organoids generate unique electrochemical signals at ≈0.3 V with intensities proportional to the amount of kidney-specific cell types. Off-target cells (i.e., non-kidney cells) produce an electrical signature at 0 V that is distinguishable from other surrounding cell types, enabling non-destructive assessment of both the differentiation, and maturation levels of kidney organoids. The developed platform can be applied to other types of organoids and is thus highly promising as a tool for organoid-based drug screening, toxicity assessment, and therapeutics.

Modeling tuberous sclerosis with organoids

[Figure: see text].