Applications of organoid technology to brain tumors

Evolution of Preclinical Models for Glioblastoma Modelling and Drug Screening

PURPOSE OF REVIEW

Isocitrate dehydrogenase wild-type glioblastoma is an extremely aggressive and fatal primary brain tumour, characterised by extensive heterogeneity and diffuse infiltration of brain parenchyma. Despite multimodal treatment and diverse research efforts to develop novel therapies, there has been limited success in improving patient outcomes. Constructing physiologically relevant preclinical models is essential to optimising drug screening processes and identifying more effective treatments.

RECENT FINDINGS

Traditional in-vitro models have provided critical insights into glioblastoma pathophysiology; however, they are limited in their ability to recapitulate the complex tumour microenvironment and its interactions with surrounding cells. In-vivo models offer a more physiologically relevant context, but often do not fully represent human pathology, are expensive, and time-consuming. These limitations have contributed to the low translational success of therapies from trials to clinic. Organoid and glioblastoma-on-a-chip technology represent significant advances in glioblastoma modelling and enable the replication of key features of the human tumour microenvironment, including its structural, mechanical, and biochemical properties. Organoids provide a 3D system that captures cellular heterogeneity and tumour architecture, while microfluidic chips offer dynamic systems capable of mimicking vascularisation and nutrient exchange. Together, these technologies hold tremendous potential for high throughput drug screening and personalised, precision medicine. This review explores the evolution of preclinical models in glioblastoma modelling and drug screening, emphasising the transition from traditional systems to more advanced organoid and microfluidic platforms. Furthermore, it aims to evaluate the advantages and limitations of both traditional and next-generation models, investigating their combined potential to address current challenges by integrating complementary aspects of specific models and techniques.

Cerebral organoid research for pediatric patients with neurological disorders

Cerebral organoids derived from human induced pluripotent stem cells offer a groundbreaking foundation for the analysis of pediatric neurological diseases. Unlike organoids from other somatic systems, cerebral organoids present unique challenges, such as the high sensitivity of neuronal cells to environmental conditions and the complexity of replicating brain-specific architectures. Cerebral organoids replicate the human brain development and pathology, enabling research on conditions such as microcephaly, Rett syndrome, autism spectrum disorders, and brain tumors. This review explores the utility of cerebral organoids for modeling diseases and testing therapeutic interventions. Despite current limitations such as variability and lack of vascularization, recent technological advancements have improved the reliability and application of such interventions. Cerebral organoids provide valuable insight into the mechanisms underlying complex neural disorders and hold promise as novel treatment strategies for pediatric neurological diseases.

Brain Organoid Research in a Post-Dobbs World

The creation and study of brain organoids may hold significant promise for understanding brain functions, disorders, and diseases. This research may also raise novel considerations and ethical concerns, but it has significant public and professional support when thoughtfully undertaken. Current legislative and judicial restrictions on abortion and pronouncements about fetal personhood could, however, have a surprisingly broad and unintended reach, even conceivably restricting the development and use of brain organoids and other biomedical and bioengineered research tools. Brain organoid research thus may constitute a cautionary tale about the risks of performative policy-making.

Cas9 Mouse Model of Skull Base Meningioma Driven by Combinational Gene Inactivation in Meningeal Cells

INTRODUCTION

Neurofibromatosis type 2 (Nf2) gene inactivation is common in sporadic and Nf2-related meningioma. There is currently scant literature describing the development of an intracranial meningioma model in animals. Given the role of Nf2 and other gene inactivation in meningeal cells, we used Cas9 mice here as the background host to establish a new animal model of skull base meningioma in this study.

AIMS

Cas9 transgenic mice were purchased from Jackson Laboratory and raised in our institution. Subsequently, meningeal cells were obtained from the Cas9 transgenic mice, cultured in medium, and passaged in vitro. We then prepared lentivirus vector pLentiCre/gRNA, which could express the elements blocking the function of four genes: Nf2, P15Ink4b, P16Ink4a, and P19Arf. We infected the meningeal cells with the lentivirus vector pLentiCre/gRNA and tested the expression of these four genes in those infected meningeal cells. Next, adeno-associated virus vector pAAVCre/gRNA was injected in vivo into the skull base meningeal cells of the neonate Cas9 transgenic mice. These mice were observed once a week and killed 10 months later for brain inspection and pathological analysis.

RESULTS

Twenty Cas9 transgenic mice were successfully bred. Five mice were killed so that meningeal cells could be extracted, cultured, and infected with the lentivirus vector pLentiCre/gRNA for 72 h in vitro. The gene function test showed that Nf2, P15Ink4b, P16Ink4a, and P19Arf were all blocked in the infected meningeal cells, which indicated that the lentivirus vector pLentiCre/gRNA could effectively block the expression of the four genes in targeted cells. Then pAAVCre/gRNA was injected into the skull base meningeal cells of 15 mice in vivo, and nine mice were observed for 10 months so that the intracranial tumor growth could be assessed. Among these nine mice, pathological analysis showed that six mice had benign meningioma subtypes similar to human meningioma, one mouse had atypical meningioma, one mouse had malignant meningioma, and one mouse had sarcoma.

CONCLUSIONS

The Cas9 mouse model of skull base meningioma generated with the Nf2 genetic defect and the combinational loss of P15Ink4b, P16Ink4a, and P19Arf could provide a new tool for investigating the pathogenesis of meningioma and the development of chemical interventions for this disease.

Preliminary study of utilizing a patient derived tumor spheroid model to augment precision therapy in metastatic brain tumors

Treating metastatic brain tumors remains a significant challenge. This study introduces and applies the Patient-Derived Tumor Spheroid (PDTS) system, an ex vivo model for precision drug testing on metastatic brain tumor. The PDTS system utilizes a decellularized extracellular matrix (dECM) derived from adipose tissue, combined with the tumor cells, to form tumor spheroids. These spheroids were subsequently used to test anticancer drugs, with results compared to the clinical outcomes observed after administering these treatments to patients. To assess the validity of the data, the correlation between the drug responses observed in the PDTS model and actual patient outcomes was analyzed. Chi-square tests evaluated the significance of associations between lab predictions and clinical outcomes, using a significance threshold of p < 0.05. In preliminary data, 17 patients met the criteria for final analysis, which showed an overall 57% accuracy (p-value = 0.463), with improvements to 73% accuracy (p-value = 0.072) when patients receiving certain treatments were excluded. This PDTS offers real-time results within three weeks, simultaneous testing of multiple drugs, and the ability to culture and store tumor cells for reproducibility. Despite some limitations, further development of this model could enhance its clinical application and improve patient outcomes.

Advances in the application of colorectal cancer organoids in precision medicine

Colorectal cancer (CRC) ranks among the most prevalent gastrointestinal tumors globally and poses a significant threat to human health. In recent years, tumor organoids have emerged as ideal models for clinical disease research owing to their ability to closely mimic the original tumor tissue and maintain a stable phenotypic structure. Organoid technology has found widespread application in basic tumor research, precision therapy, and new drug development, establishing itself as a reliable preclinical model in CRC research. This has significantly advanced individualized and precise tumor therapies. Additionally, the integration of single-cell technology has enhanced the precision of organoid studies, offering deeper insights into tumor heterogeneity and treatment response, thereby contributing to the development of personalized treatment approaches. This review outlines the evolution of colorectal cancer organoid technology and highlights its strengths in modeling colorectal malignancies. This review also summarizes the progress made in precision tumor medicine and addresses the challenges in organoid research, particularly when organoid research is combined with single-cell technology. Furthermore, this review explores the future potential of organoid technology in the standardization of culture techniques, high-throughput screening applications, and single-cell multi-omics integration, offering novel directions for future colorectal cancer research.

A tumorigenicity evaluation platform for cell therapies based on brain organoids

BACKGROUND

Tumorigenicity represents a critical challenge in stem cell-based therapies requiring rigorous monitoring. Conventional approaches for tumorigenicity evaluation are based on animal models and have numerous limitations. Brain organoids, which recapitulate the structural and functional complexity of the human brain, have been widely used in neuroscience research. However, the capacity of brain organoids for tumorigenicity evaluation needs to be further elucidated.

METHODS

A cerebral organoid model produced from human pluripotent stem cells (hPSCs) was employed. Meanwhile, to enhance the detection sensitivity for potential tumorigenic cells, we created a glioblastoma-like organoid (GBM organoid) model from TP53-/-/PTEN-/- hPSCs to provide a tumor microenvironment for injected cells. Midbrain dopamine (mDA) cells from human embryonic stem cells were utilized as a cell therapy product. mDA cells, hPSCs, mDA cells spiked with hPSCs, and immature mDA cells were then injected into the brain organoids and NOD SCID mice. The injected cells within the brain organoids were characterized, and compared with those injected in vivo to evaluate the capability of the brain organoids for tumorigenicity evaluation. Single-cell RNA sequencing was performed to identify the differential gene expression between the cerebral organoids and the GBM organoids.

RESULTS

Both cerebral organoids and GBM organoids supported maturation of the injected mDA cells. The hPSCs and immature mDA cells injected in the GBM organoids showed a significantly higher proliferative capacity than those injected in the cerebral organoids and in NOD SCID mice. Furthermore, the spiked hPSCs were detectable in both the cerebral organoids and the GBM organoids. Notably, the GBM organoids demonstrated a superior capacity to enhance proliferation and pluripotency of spiked hPSCs compared to the cerebral organoids and the mouse model. Kyoto Encyclopedia of Genes and Genomes analysis revealed upregulation of tumor-related metabolic pathways and cytokines in the GBM organoids, suggesting that these factors underlie the high detection sensitivity for tumorigenicity evaluation.

CONCLUSIONS

Our findings suggest that brain organoids could represent a novel and effective platform for evaluating the tumorigenic risk in stem cell-based therapies. Notably, the GBM organoids offer a superior platform that could complement or potentially replace traditional animal-based models for tumorigenicity evaluation.

Co-culture models for investigating cellular crosstalk in the glioma microenvironment

Glioma is the most prevalent primary malignant tumor in the central nervous system (CNS). It represents a diverse group of brain malignancies characterized by the presence of various cancer cell types as well as an array of noncancerous cells, which together form the intricate glioma tumor microenvironment (TME). Understanding the interactions between glioma cells/glioma stem cells (GSCs) and these noncancerous cells is crucial for exploring the pathogenesis and development of glioma. To invesigate these interactions requires in vitro co-culture models that closely mirror the actual TME in vivo. In this review, we summarize the two- and three-dimensional in vitro co-culture model systems for glioma-TME interactions currently available. Furthermore, we explore common glioma-TME cell interactions based on these models, including interactions of glioma cells/GSCs with endothelial cells/pericytes, microglia/macrophages, T cells, astrocytes, neurons, or other multi-cellular interactions. Together, this review provides an update on the glioma-TME interactions, offering insights into glioma pathogenesis.

The unfolded protein response machinery in glioblastoma genesis, chemoresistance and as a druggable target

BACKGROUND

The role of the unfolded protein response (UPR) has been progressively unveiled over the last decade and several studies have investigated its implication in glioblastoma (GB) development. The UPR restores cellular homeostasis by triggering the folding and clearance of accumulated misfolded proteins in the ER consecutive to endoplasmic reticulum stress. In case it is overwhelmed, it induces apoptotic cell death. Thus, holding a critical role in cell fate decisions.

METHODS

This article, reviews how the UPR is implicated in cell homeostasis maintenance, then surveils the evidence supporting the UPR involvement in GB genesis, progression, angiogenesis, GB stem cell biology, tumor microenvironment modulation, extracellular matrix remodeling, cell fate decision, invasiveness, and grading. Next, it concurs the evidence showing how the UPR mediates GB chemoresistance-related mechanisms.

RESULTS

The UPR stress sensors IRE1, PERK, and ATF6 with their regulator GRP78 are upregulated in GB compared to lower grade gliomas and normal brain tissue. They are activated in response to oncogenes and are implicated at different stages of GB progression, from its genesis to chemoresistance and relapse. The UPR arms can be effectors of apoptosis as mediators or targets.

CONCLUSION

Recent research has established the role of the UPR in GB pathophysiology and chemoresistance. Targeting its different sensors have shown promising in overcoming GB chomo- and radioresistance and inducing apoptosis.

Establishment and characterization of novel high mucus-producing lung tumoroids derived from a patient with pulmonary solid adenocarcinoma

Among mucus-producing lung cancers, invasive mucinous adenocarcinoma of the lung is a rare and unique subtype of pulmonary adenocarcinoma. Notably, mucus production may also be observed in the five subtypes of adenocarcinoma grouped under the higher-level diagnosis of Invasive Non-mucinous Adenocarcinomas (NMA). Overlapping pathologic features in mucus-producing tumors can cause diagnostic confusion with significant clinical consequences. In this study, we established lung tumoroids, PDT-LUAD#99, from a patient with NMA and mucus production. The tumoroids were derived from the malignant pleural effusion of a patient with lung cancer and have been successfully developed for long-term culture (> 11 months). Karyotyping by fluorescence in situ hybridization using an alpha-satellite probe showed that tumoroids harbored aneuploid karyotypes. Subcutaneous inoculation of PDT-LUAD#99 lung tumoroids into immunodeficient mice resulted in tumor formation, suggesting that the tumoroids were derived from cancer. Xenografts from PDT-LUAD#99 lung tumoroids reproduced the solid adenocarcinoma with mucin production that was observed in the patient's metastatic lymph nodes. Immunoblot analysis showed MUC5AC secretion into the culture supernatant of PDT-LUAD#99 lung tumoroids, which in contradistinction was barely detected in the culture supernatants of NCI-A549 and NCI-H2122 pulmonary adenocarcinoma cells known for their mucin-producing abilities. Here, we established a novel high-mucus-producing lung tumoroids from a solid adenocarcinoma. This preclinical model may be useful for elucidating the pathogenesis of mucus-producing lung cancer.

Tumor Organoids: The Era of Personalized Medicine

The strategies of future medicine are aimed to modernize and integrate quality approaches including early molecular-genetic profiling, identification of new therapeutic targets and adapting design for clinical trials, personalized drug screening (PDS) to help predict and individualize patient treatment regimens. In the past decade, organoid models have emerged as an innovative in vitro platform with the potential to realize the concept of patient-centered medicine. Organoids are spatially restricted three-dimensional clusters of cells ex vivo that self-organize into complex functional structures through genetically programmed determination, which is crucial for reconstructing the architecture of the primary tissue and organs. Currently, there are several strategies to create three-dimensional (3D) tumor systems using (i) surgically resected patient tissue (PDTOs, patient-derived tumor organoids) or (ii) single tumor cells circulating in the patient's blood. Successful application of 3D tumor models obtained by co-culturing autologous tumor organoids (PDTOs) and peripheral blood lymphocytes have been demonstrated in a number of studies. Such models simulate a 3D tumor architecture in vivo and contain all cell types characteristic of this tissue, including immune system cells and stem cells. Components of the tumor microenvironment, such as fibroblasts and immune system cells, affect tumor growth and its drug resistance. In this review, we analyzed the evolution of tumor models from two-dimensional (2D) cell cultures and laboratory animals to 3D tissue-specific tumor organoids, their significance in identifying mechanisms of antitumor response and drug resistance, and use of these models in drug screening and development of precision methods in cancer treatment.

Emerging roles of 3D-culture systems in tackling tumor drug resistance

Drug resistance that affects patients universally is a major challenge in cancer therapy. The development of drug resistance in cancer cells is a multifactor event, and its process involves numerous mechanisms that allow these cells to evade the effect of treatments. As a result, the need to understand the molecular mechanisms underlying cancer drug sensitivity is imperative. Traditional 2D cell culture systems have been utilized to study drug resistance, but they often fail to mimic the 3D milieu and the architecture of real tissues and cell-cell interactions. As a result of this, 3D cell culture systems are now considered a comprehensive model to study drug resistance in vitro. Cancer cells exhibit an in vivo behavior when grown in a three-dimensional environment and react to therapy more physiologically. In this review, we discuss the relevance of main 3D culture systems in the study of potential approaches to overcome drug resistance and in the identification of personalized drug targets with the aim of developing patient-specific treatment strategies that can be put in place when resistance emerges.