Human gastric cancer modelling using organoids

Harnessing the Potential of Stem Cells for Disease Modeling: Progress and Promises

Ex vivo cell/tissue-based models are an essential step in the workflow of pathophysiology studies, assay development, disease modeling, drug discovery, and development of personalized therapeutic strategies. For these purposes, both scientific and pharmaceutical research have adopted ex vivo stem cell models because of their better predictive power. As matter of a fact, the advancing in isolation and in vitro expansion protocols for culturing autologous human stem cells, and the standardization of methods for generating patient-derived induced pluripotent stem cells has made feasible to generate and investigate human cellular disease models with even greater speed and efficiency. Furthermore, the potential of stem cells on generating more complex systems, such as scaffold-cell models, organoids, or organ-on-a-chip, allowed to overcome the limitations of the two-dimensional culture systems as well as to better mimic tissues structures and functions. Finally, the advent of genome-editing/gene therapy technologies had a great impact on the generation of more proficient stem cell-disease models and on establishing an effective therapeutic treatment. In this review, we discuss important breakthroughs of stem cell-based models highlighting current directions, advantages, and limitations and point out the need to combine experimental biology with computational tools able to describe complex biological systems and deliver results or predictions in the context of personalized medicine.

Generating and Utilizing Murine Cas9-Expressing Intestinal Organoids for Large-Scale Knockout Genetic Screening

Organoid culture faithfully reproduces the in vivo characteristics of the intestinal/colon epithelium and elucidates molecular mechanisms underlying the regulation of stem cell compartment that, if altered, may lead tumorigenesis. CRISPR-Cas9 based editing technology has provided promising opportunities for targeted loss-of-function mutations at chosen sites in the genome of eukaryotes. Herein, we demonstrate a CRISPR/Cas9-mediated mutagenesis-based screening method using murine intestinal organoids by investigating the phenotypical morphology of Cas9-expressing murine intestinal organoids. Murine intestinal crypts can be isolated and seeded into Matrigel and grown into stable organoid lines. Organoids subsequently transduced and selected to generate Cas9 expressing organoids. These organoids can be further transduced with the second lentiviruses expressing guide RNA (gRNA) (s) and screened for 8-10 days using bright-field and fluorescent microscopy to determine possible morphological or phenotypical abnormalities. Via phenotypical screening analysis, the candidate knockouts can be selected based on differential abnormal growth pattern vs their untransduced or lenti-GFP transduced controls. Further assessment of these knockout organoids can be done via phalloidin and propidium iodide (PI) staining, proliferation assay and qRT-PCR and also biochemical analysis. This CRISPR/Cas9 organoid mutagenesis-based screening method provides a reliable and rapid approach for investigating large numbers of genes with unknown/poorly identified biological functions. Knockout intestinal organoids can be associated with the key biological function of the gene(s) in development, homeostasis, disease progression, tumorigenesis, and drug screening, thereby reducing and potentially replacing animal models.

Mouse Models of Human Gastric Cancer Subtypes With Stomach-Specific CreERT2-Mediated Pathway Alterations

BACKGROUND & AIMS

Patterns of genetic alterations characterize different molecular subtypes of human gastric cancer. We aimed to establish mouse models of these subtypes.

METHODS

We searched databases to identify genes with unique expression in the stomach epithelium, resulting in the identification of Anxa10. We generated mice with tamoxifen-inducible Cre recombinase (CreERT2) in the Anxa10 gene locus. We created 3 mouse models with alterations in pathways that characterize the chromosomal instability (CIN) and the genomically stable (GS) subtypes of human gastric cancer: Anxa10-CreER^T2;Kras^G12D/+;Tp53^R172H/+;Smad4^fl/f (CIN mice), Anxa10-CreER^T2;Cdh1^fl/fl;Kras^G12D/+;Smad4^fl/fl (GS-TGBF mice), and Anxa10-CreER^T2;Cdh1^fl/fl;Kras^G12D/+;Apc^fl/fl (GS-Wnt mice). We analyzed tumors that developed in these mice by histology for cell types and metastatic potential. We derived organoids from the tumors and tested their response to chemotherapeutic agents and the epithelial growth factor receptor signaling pathway inhibitor trametinib.

RESULTS

The gastric tumors from the CIN mice had an invasive phenotype and formed liver and lung metastases. The tumor cells had a glandular morphology, similar to human intestinal-type gastric cancer. The gastric tumors from the GS-TGFB mice were poorly differentiated with diffuse morphology and signet ring cells, resembling human diffuse-type gastric cancer. Cells from these tumors were invasive, and mice developed peritoneal carcinomatosis and lung metastases. GS-Wnt mice developed adenomatous tooth-like gastric cancer. Organoids derived from tumors of GS-TGBF and GS-Wnt mice were more resistant to docetaxel, whereas organoids from the CIN tumors were more resistant to trametinib.

CONCLUSIONS

Using a stomach-specific CreERT2 system, we created mice that develop tumors with morphologic similarities to subtypes of human gastric cancer. These tumors have different patterns of local growth, metastasis, and response to therapeutic agents. They can be used to study different subtypes of human gastric cancer.

Malignant ascites-derived organoid (MADO) cultures for gastric cancer in vitro modelling and drug screening

PURPOSE

Malignant ascites (MA) is a common manifestation in advanced gastric cancer with peritoneal carcinomatosis and usually indicates a poor prognosis. However, lack of in vitro models that can faithfully recapitulate the characteristics of tumour cells in ascites hinders related researches. Tumour organoids have emerged as a robust in vitro model for tumour research and drug screening. Hence, we aimed to generate a 3-D in vitro organoid cultures from malignant ascites of gastric cancer for disease modelling and drug screening.

METHODS

Eleven MADOs were generated from the MA tumour cells of gastric cancer patients. We made comparisons between MADOs and original MA tumour cells in histopathology by immunohistochemistry and genomics by whole-exome sequencing. In order to evaluate MADOs as functional in vitro disease models, we tested whether MADOs could be used for drug sensitivity screens.

RESULTS

Eleven MADO cultures from human gastric cancer were established. MADOs demonstrated divergent growth characteristics and morphologies. MADO cultures preserve the histological architecture, genomic landscape of the corresponding MA tumour cells. MADOs exhibited heterogeneous responses to standard-of-care chemotherapeutics.

CONCLUSIONS

We generated MADOs modelling characteristics and mutated genes of MA tumour cells. A broad range of intrinsic MADO response to conventional chemotherapeutics suggests MADOs are amenable to drug screening.

Towards manufacturing of human organoids

Organoids are 3D miniature versions of organs produced from stem cells derived from either patient or healthy individuals in vitro that recapitulate the actual organ. Organoid technology has ensured an alternative to pre-clinical drug testing as well as being currently used for "personalized medicine" to modulate the treatment as they are uniquely identical to each patient's genetic makeup. Researchers have succeeded in producing different types of organoids and have demonstrated their efficient application in various fields such as disease modeling, pathogenesis, drug screening and regenerative medicine. There are several protocols for fabricating organoids in vitro. In this comprehensive review, we focus on key methods of producing organoids and manufacturing considerations for each of them while providing insights on the advantages, applications and challenges of these methods. We also discuss pertinent challenges faced during organoid manufacturing and various bioengineering approaches that can improve the organoid manufacturing process. Organoids size, number and the reproducibility of the fabrication processes are touched upon. The major factors which are involved in organoids manufacturing such as spatio-temporal controls, scaffold designs/types, cell culture parameters and vascularization have been highlighted.

circZNF609 promotes the proliferation and migration of gastric cancer by sponging miR-483-3p and regulating CDK6

Objective

To explore the regulatory effects of circZNF609 on proliferative and migratory capacities of gastric cancer (GC) and its underlying mechanism.

Methods

Expression level of circZNF609, CDK6 and miR-483-3p in GC tissues and cells were detected qRT-PCR verification. CCK-8 and transwell assay were conducted the cell viability and migratory capacities of GC cells. Dual luciferase assay was enrolled to confirm the interaction among circZNF609, CDK6 and miR-483-3p. Western blot was used to detect the protein level of CDK6.

Results

Expression levels of circZNF609 were higher in GC patients by qRT-PCR.GC patients with higher expression of circZNF609 were expected to have a higher TNM stage and lower 5-year survival than those with lower expression. ROC curves showed a well diagnostic value of circZNF609 in GC. Treatment of RNase R in GC cells downregulated the expression of ZNF609, whereas circZNF609 expression did not change. Furthermore, cytoplasmic expression of circZNF609 was higher than those of nuclear expression. Besides, biological experiments indicated that overexpression of circZNF609 promoted the proliferative and migratory capacities of GC cells. To demonstrate the underlying mechanism of circZNF609, we found that circZNF609 bound to miR-483-3p, which presented a lower expression in GC tissues than that of paracancerous tissues. Both circZNF609 and miR-483-3p could bind to Ago2, suggesting that circZNF609 may act as a sponge of miR-483-3p. In addition, the effect of overexpressed circZNF609 on cellular behaviors of GC cells were partly reversed by overexpression of miR-483-3p. Bioinformatics suggested that CDK6 has a potential binding site with miR-483-3p. The expression of CDK6 markedly increased in GC tissues and cells, which was negatively correlated with miR-483-3p expression. Dual-luciferase reporter gene results indicated that miR-483-3p could bind to the 3’-UTR of CDK6. Moreover, miR-483-3p downregulated CDK6 at both mRNA and protein levels. Overexpression of miR-483-3p inhibited proliferative and migratory capacities of GC cells, which were reversed by CDK6 overexpression.

Conclusion

In summary, the expression of circZNF609 is upregulated in GC. CircZNF609 can be used as the sponge of miR-483-3p to regulate the expression level of CDK6, thus participating in the progression of GC by regulating the proliferative and migratory capacities of GC cells.

Review: Gastric cancer-Clinical aspects

Gastric cancer (GC) was responsible for over 1 000 000 new cases in 2018 and an estimated 783 000 deaths, making it still the fifth most frequently diagnosed cancer and the third leading cause of cancer deaths in both sexes worldwide. Divergent trends for GC incidence were observed in the USA. Incidence rates, particularly for non-cardia GC, were stable or increasing among persons aged <50 years. In an analysis of data from a public hospital database in Hong Kong, treatment of Helicobacter pylori infection was associated with a lower risk of GC, particularly in older subjects who received treatment ≥10 years before. Based on the results of a 16-year endoscopy-based follow-up eradication trial, patients with incomplete-type intestinal metaplasia (IM) should receive endoscopic surveillance upon H. pylori eradication therapy. Updated guidelines on the endoscopic surveillance of preneoplastic conditions of the stomach (MAPS II) have been published. In the RAINFALL trial, the addition of ramucirumab to a backbone chemotherapy as a first-line regimen failed to improve overall survival (OS) of patients with metastatic disease. Also, pembrolizumab did not prolong OS when compared to paclitaxel in the second-line treatment of patients with advanced GC or esophagogastric junction (EGJ) cancer. Trifluridine/tipiracil improved OS by 2.1 months in the third or further treatment line of patients with advanced GC. In a systematic investigation conducted on Chinese patients with GC, CLDN18-ARHGAP26/6 fusion was associated with signet-ring cell content and was prognostic for a worse outcome and predictive for no benefit from oxaliplatin/fluoropyrimidine-based chemotherapy. Organoid cultures represent an appealing model that may be applied for therapy response testing in the near future.

Clinical Implementation of Precision Medicine in Gastric Cancer

Gastric cancer (GC) is one of the deadliest malignancies in the world. Currently, clinical treatment decisions are mostly made based on the extent of the tumor and its anatomy, such as tumor-node-metastasis staging. Recent advances in genome-wide molecular technology have enabled delineation of the molecular characteristics of GC. Based on this, efforts have been made to classify GC into molecular subtypes with distinct prognosis and therapeutic response. Simplified algorithms based on protein and RNA expressions have been proposed to reproduce the GC classification in the clinical field. Furthermore, a recent study established a single patient classifier (SPC) predicting the prognosis and chemotherapy response of resectable GC patients based on a 4-gene real-time polymerase chain reaction assay. GC patient stratification according to SPC will enable personalized therapeutic strategies in adjuvant settings. At the same time, patient-derived xenografts and patient-derived organoids are now emerging as novel preclinical models for the treatment of GC. These models recapitulate the complex features of the primary tumor, which is expected to facilitate both drug development and clinical therapeutic decision making. An integrated approach applying molecular patient stratification and patient-derived models in the clinical realm is considered a turning point in precision medicine in GC.

Disease modelling in human organoids

The past decade has seen an explosion in the field of in vitro disease modelling, in particular the development of organoids. These self-organizing tissues derived from stem cells provide a unique system to examine mechanisms ranging from organ development to homeostasis and disease. Because organoids develop according to intrinsic developmental programmes, the resultant tissue morphology recapitulates organ architecture with remarkable fidelity. Furthermore, the fact that these tissues can be derived from human progenitors allows for the study of uniquely human processes and disorders. This article and accompanying poster highlight the currently available methods, particularly those aimed at modelling human biology, and provide an overview of their capabilities and limitations. We also speculate on possible future technological advances that have the potential for great strides in both disease modelling and future regenerative strategies.

Summary: Human organoids are important tools for modelling disease. This At a Glance article summarises the current organoid models of several human diseases, and discusses future prospects for these technologies.

A more physiological approach to lipid metabolism alterations in cancer: CRC-like organoids assessment

Precision medicine might be the response to the recent questioning of the use of metformin as an anticancer drug in colorectal cancer (CRC). Thus, in order to establish properly its benefits, metformin application needs to be assayed on the different progression stages of CRC. In this way, intestinal organoids imply a more physiological tool, representing a new therapeutic opportunity for CRC personalized treatment to assay tumor stage-dependent drugs. The previously reported lipid metabolism-related axis, Acyl-CoA synthetases/ Stearoyl-CoA desaturase (ACSLs/SCD), stimulates colon cancer progression and metformin is able to rescue the invasive and migratory phenotype conferred to cancer cells upon this axis overexpression. Therefore, we checked ACSL/SCD axis status, its regulatory miRNAs and the effect of metformin treatment in intestinal organoids with the most common acquired mutations in a sporadic CRC (CRC-like organoids) as a model for specific and personalized treatment. Despite ACSL4 expression is upregulated progressively in CRC-like organoids, metformin is able to downregulate its expression, especially in the first two stages (I, II). Besides, organoids are clearly more sensitive in the first stage (Apc mutated) to metformin than current chemotherapeutic drugs such as fluorouracil (5-FU). Metformin performs an independent "Warburg effect" blockade to cancer progression and is able to reduce crypt stem cell markers expression such as LGR5+. These results suggest a putative increased efficiency of the use of metformin in early stages of CRC than in advanced disease.

Utilizing gastric cancer organoids to assess tumor biology and personalize medicine

While the incidence and mortality of gastric cancer (GC) have declined due to public health programs, it remains the third deadliest cancer worldwide. For patients with early disease, innovative endoscopic and complex surgical techniques have improved survival. However, for patients with advanced disease, there are limited treatment options and survival remains poor. Therefore, there is an urgent need for more effective therapies. Since novel therapies require extensive preclinical testing prior to human trials, it is important to identify methods to expedite this process. Traditional cancer models are restricted by the inability to accurately recapitulate the primary human tumor, exorbitant costs, and the requirement for extended periods of development time. An emerging in vitro model to study human disease is the patient-derived organoid, which is a three-dimensional system created from fresh surgical or biopsy tissues of a patient’s gastric tumor. Organoids are cultured in plastic wells and suspended in a gelatinous matrix, providing a substrate for extension and growth in all dimensions. They are rapid-growing and highly representative of the molecular landscape, histology, and morphology of the various subtypes of GC. Organoids uniquely model tumor initiation and growth, including steps taken by normal stomach cells to transform into invasive, intestinal-type tumor cells. Additionally, they provide ample material for biobanking and screening novel therapies. Lastly, organoids are a promising model for personalized therapy and warrant further investigation in drug sensitivity studies for GC patients.

3D model for CAR-mediated cytotoxicity using patient-derived colorectal cancer organoids

Immunotherapy using chimeric antigen receptor (CAR)-engineered lymphocytes has shown impressive results in leukemia. However, for solid tumors such as colorectal cancer (CRC), new preclinical models are needed that allow to test CAR-mediated cytotoxicity in a tissue-like environment. Here, we developed a platform to study CAR cell cytotoxicity against 3-dimensional (3D) patient-derived colon organoids. Luciferase-based measurement served as a quantitative read-out for target cell viability. Additionally, we set up a confocal live imaging protocol to monitor effector cell recruitment and cytolytic activity at a single organoid level. As proof of principle, we demonstrated efficient targeting in diverse organoid models using CAR-engineered NK-92 cells directed toward a ubiquitous epithelial antigen (EPCAM). Tumor antigen-specific cytotoxicity was studied with CAR-NK-92 cells targeting organoids expressing EGFRvIII, a neoantigen found in several cancers. Finally, we tested a novel CAR strategy targeting FRIZZLED receptors that show increased expression in a subgroup of CRC tumors. Here, comparative killing assays with normal organoids failed to show tumor-specific activity. Taken together, we report a sensitive in vitro platform to evaluate CAR efficacy and tumor specificity in a personalized manner.

Establishing Pure Cancer Organoid Cultures: Identification, Selection and Verification of Cancer Phenotypes and Genotypes

Precision medicine requires in vitro models which will both faithfully recapitulate the features of an individual's disease and enable drug testing on a wide variety of samples covering the greatest range of phenotypes possible for a particular disease. Organoid technology has immense potential to fulfill this demand, but it will be necessary to develop robust protocols that enable the generation of organoids in a dependable manner from nearly every patient. Here we provide a user's guide, including detailed step-by-step protocols, to the establishment, isolation and verification of gastric cancer organoids. Selection strategies include omission of growth factors, addition of drugs, isolation of distinct phenotypes and generation of monoclonal lines. For confirmation of cancer identity, we use sequencing, drug selection, karyotyping and histology. While we specify these protocols for human gastric cancer organoids here, the methods described are applicable to organoids derived from other tissues as well.

CFTR Expression Analysis for Subtyping of Human Pancreatic Cancer Organoids

Background

Organoid cultures of human pancreatic ductal adenocarcinoma (PDAC) have become a promising tool for tumor subtyping and individualized chemosensitivity testing. PDACs have recently been grouped into different molecular subtypes with clinical impact based on cytokeratin-81 (KRT81) and hepatocyte nuclear factor 1A (HNF1A). However, a suitable antibody for HNF1A is currently unavailable. The present study is aimed at establishing subtyping in PDAC organoids using an alternative marker.

Methods

A PDAC organoid biobank was generated from human primary tumor samples containing 22 lines. Immunofluorescence staining was established and done for 10 organoid lines for cystic fibrosis transmembrane conductance regulator (CFTR) and KRT81. Quantitative real-time PCR (qPCR) was performed for CFTR and HNF1A. A chemotherapeutic drug response analysis was done using gemcitabine, 5-FU, oxaliplatin, and irinotecan.

Results

A biobank of patient-derived PDAC organoids was established. The efficiency was 71% (22/31) with 68% for surgical resections and 83% for fine needle aspirations. Organoids could be categorized into the established quasimesenchymal, exocrine-like, and classical subtypes based on KRT81 and CFTR immunoreactivity. CFTR protein expression was confirmed on the transcript level. CFTR and HNF1A transcript expression levels positively correlated (n = 10; r = 0.927; p = 0.001). PDAC subtypes of the primary tumors and the corresponding organoid lines were identical for most of the cases analyzed (6/7). Treatment with chemotherapeutic drugs revealed tendencies but no significant differences regarding drug responses.

Conclusions

Human PDAC organoids can be classified into known subtypes based on KRT81 and CFTR immunoreactivity. CFTR and HNF1A mRNA levels correlated well. Furthermore, subtype-specific immunoreactivity matched well between PDAC organoids and the respective primary tumor tissue. Subtyping of human PDACs using CFTR might constitute an alternative to HNF1A and should be further investigated.

MIR-1265 regulates cellular proliferation and apoptosis by targeting calcium binding protein 39 in gastric cancer and, thereby, impairing oncogenic autophagy

Increasing evidence indicates that microRNAs (miRNAs) play an important role in various tumors by regulating downstream target genes and diverse signaling pathways. Herein, we confirmed miR-1265 expression in gastric cancer (GC) using the Cancer Genome Atlas (TCGA) database and assessed the level of miR-1265 expression in clinical specimens and cell lines. We found that miR-1265 expression was negatively correlated with tumor size. Further functional analysis revealed that miR-1265 suppresses cellular proliferation and autophagy while inducing apoptosis in GC cells. A luciferase reporter assay was used to identify an miR-1265 targeted gene, calcium binding protein 39 (CAB39), which is an essential upstream regulator in the AMPK-mTOR signaling pathway. Upregulation or downregulation of CAB39 expression reversed the effects of miR-1265 overexpression or inhibition, respectively. Notably, the knockdown of autophagy-related gene 12 (ATG12) impaired the effects of miR-1265 inhibition or CAB39 overexpression in GC. MiR-1265 also suppressed the growth of GC cells in vivo and that of human gastric organoids. Altogether, our results show that miR-1265 suppresses GC progression and oncogenic autophagy by reducing CAB39 expression and regulating the AMPK-mTOR signaling pathway. Therefore, miR-1265 may represent a potential therapeutic target for GC.

Tumor organoids: From inception to future in cancer research

Tumor models have created new avenues for personalized medicine and drug development. A new culture model derived from a three-dimensional system, the tumor organoid, is gradually being used in many fields. An organoid can simulate the physiological structure and function of tissue in situ and maintain the characteristics of tumor cells in vivo, overcoming the disadvantages of traditional experimental tumor models. Organoids can mimic pathological features of tumors and maintain genetic stability, making them suitable for both molecular mechanism studies and pharmacological experiments of clinical transformation. In addition, the application of tumor organoids combined with other technologies, such as liquid biopsy technology, microraft array (MRA), and high-content screening (HCS), for the development of personalized diagnosis and cancer treatment has a promising future. In this review, we introduce the evolution of organoids and discuss their specific application and advantages. We also summarize the characteristics of several tumor organoids culture systems.

A subset of diffuse-type gastric cancer is susceptible to mTOR inhibitors and checkpoint inhibitors

BACKGROUND

Mechanistic target of rapamycin (mTOR) pathway is essential for the growth of gastric cancer (GC), but mTOR inhibitor everolimus was not effective for the treatment of GCs. The Cancer Genome Atlas (TCGA) researchers reported that most diffuse-type GCs were genomically stable (GS). Pathological analysis suggested that some diffuse-type GCs developed from intestinal-type GCs.

METHODS

We established patient-derived xenograft (PDX) lines from diffuse-type GCs, and searched for drugs that suppressed their growth. Diffuse-type GCs were classified into subtypes by their gene expression profiles.

RESULTS

mTOR inhibitor temsirolimus strongly suppressed the growth of PDX-derived diffuse-type GC-initiating cells, which was regulated via Wnt-mTOR axis. These cells were microsatellite unstable (MSI) or chromosomally unstable (CIN), inconsistent with TCGA report. Diffuse-type GCs in TCGA cohort could be classified into two clusters, and GS subtype was major in cluster I while CIN and MSI subtypes were predominant in cluster II where PDX-derived diffuse-type GC cells were included. We estimated that about 9 and 55% of the diffuse-type GCs in cluster II were responders to mTOR inhibitors and checkpoint inhibitors, respectively, by identifying PIK3CA mutations and MSI condition in TCGA cohort. These ratios were far greater than those of diffuse-type GCs in cluster I or intestinal-type GCs. Further analysis suggested that diffuse-type GCs in cluster II developed from intestinal-type GCs while those in cluster I from normal gastric epithelial cells.

CONCLUSION

mTOR inhibitors and checkpoint inhibitors might be useful for the treatment of a subset of diffuse-type GCs which may develop from intestinal-type GCs.

Three-Dimensional Organoids in Cancer Research: The Search for the Holy Grail of Preclinical Cancer Modeling

Most solid tumors become therapy resistant and will relapse, with no durable treatment option available. One major impediment to our understanding of cancer biology and finding innovative approaches to cancer treatment stems from the lack of better preclinical tumor models that address and explain tumor heterogeneity and person-to-person differences in therapeutic and toxic responses. Past cancer research has been driven by inadequate in vitro assays utilizing two-dimensional monolayers of cancer cells and animal models. Additionally, animal models do not truly mimic the original human tumor, are time consuming, and usually costly. New preclinical models are needed for innovation in cancer translational research. Hence, it is time to welcome the three-dimensional (3D) organoids: self-organizing cells grown in 3D culture systems mimicking the parent tissues from which the primary cells originate. The 3D organoids offer deeper insights into the crucial cellular processes in tissue and organ formation and pathological processes. Generation of near-perfect physiological microenvironments allow 3D organoids to couple with gene editing tools, such as the clustered regularly interspersed short palindromic repeat (CRISPR)/CRISPR-associated 9 and the transcription activator-like effector nucleases to model human diseases, offering distinct advantages over current models. We explain in this expert review that through recapitulating patients' normal and tumor tissues, organoid technology can markedly advance personalized medicine and help reveal once hidden aspects of cancers. The use of defined tissue- or organ-specific matrices, among other factors, will likely allow organoid technology to realize its potential in innovating many fields of life sciences.

Organoid technology in disease modelling, drug development, personalized treatment and regeneration medicine

Organoid technology bridges the gap between conventional two-dimensional cell line culture and in vivo models. The near-physiological technology can virtually recapitulates organ development and human diseases, such as infectious diseases, genetic abnormality and even cancers. In addition, organoids can more accurately predict drug responses, and serve as an excellent platform for drug development, including efficacy evaluation, toxicity testing and pharmacokinetics analysis. Furthermore, organoids can also be exploited to explore the possible optimized treatment strategies for each individual patient. Besides, organoid technology is a promising strategy for regeneration medicine and transplantation use, which can overcome the deficiency in the supply of healthy donor tissues and inherent immunological rejection through establishing isogenic organoids from minuscule amounts of patient biopsies. Collectively, organoids hold enormous potential for clinical applications and bring basic research closer to clinical practice. In this review, we described common organoid lines, summarized the potential clinical applications, and outlined the current limitations.

Modeling Hematological Diseases and Cancer With Patient-Specific Induced Pluripotent Stem Cells

The advent of induced pluripotent stem cells (iPSCs) together with recent advances in genome editing, microphysiological systems, tissue engineering and xenograft models present new opportunities for the investigation of hematological diseases and cancer in a patient-specific context. Here we review the progress in the field and discuss the advantages, limitations, and challenges of iPSC-based malignancy modeling. We will also discuss the use of iPSCs and its derivatives as cellular sources for drug target identification, drug development and evaluation of pharmacological responses.

An Organoid-Based Preclinical Model of Human Gastric Cancer

BACKGROUND & AIMS

Our goal was to develop an initial study for the proof of concept whereby gastric cancer organoids are used as an approach to predict the tumor response in individual patients.

METHODS

Organoids were derived from resected gastric cancer tumors (huTGOs) or normal stomach tissue collected from sleeve gastrectomies (huFGOs). Organoid cultures were treated with standard-of-care chemotherapeutic drugs corresponding to patient treatment: epirubicin, oxaliplatin, and 5-fluorouracil. Organoid response to chemotherapeutic treatment was correlated with the tumor response in each patient from whom the huTGOs were derived. HuTGOs were orthotopically transplanted into the gastric mucosa of NOD scid gamma mice.

RESULTS

Whereas huFGOs exhibited a half maximal inhibitory concentration that was similar among organoid lines, divergent responses and varying half maximal inhibitory concentration values among the huTGO lines were observed in response to chemotherapeutic drugs. HuTGOs that were sensitive to treatment were derived from a patient with a near complete tumor response to chemotherapy. However, organoids resistant to treatment were derived from patients who exhibited no response to chemotherapy. Orthotropic transplantation of organoids resulted in the engraftment and development of human adenocarcinoma. RNA sequencing revealed that huTGOs closely resembled the patient's native tumor tissue and not commonly used gastric cancer cell lines and cell lines derived from the organoid cultures.

CONCLUSIONS

The treatment of patient-derived organoids alongside patients from whom cultures were derived will ultimately test their usefulness to predict individual therapy response and patient outcome.

Organoid technology and applications in cancer research

During the past decade, the three-dimensional organoid technology has sprung up and become more and more popular among researchers. Organoids are the miniatures of in vivo tissues and organs, and faithfully recapitulate the architectures and distinctive functions of a specific organ.

These amazing three-dimensional constructs represent a promising, near-physiological model for human cancers, and tremendously support diverse potential applications in cancer research. Up to now, highly efficient establishment of organoids can be achieved from both normal and malignant tissues of patients. Using this bioengineered platform, the links of infection-cancer progression and mutation-carcinogenesis are feasible to be modeled. Another potential application is that organoid technology facilitates drug testing and guides personalized therapy. Although organoids still fail to model immune system accurately, co-cultures of organoids and lymphocytes have been reported in several studies, bringing hope for further application of this technology in immunotherapy. In addition, the potential value in regeneration medicine might be another paramount branch of organoid technology, which might refine current transplantation therapy through the replacement of irreversibly progressively diseased organs with isogenic healthy organoids.

In conclusion, organoids represent an excellent preclinical model for human tumors, promoting the translation from basic cancer research to clinical practice. In this review, we outline organoid technology and summarize its applications in cancer research.