Guided self-organization and cortical plate formation in human brain organoids

Modelling human brain development and disease with organoids

Organoids are systems derived from pluripotent stem cells at the interface between traditional monolayer cultures and in vivo animal models. The structural and functional characteristics of organoids enable the modelling of early stages of brain development in a physiologically relevant 3D environment. Moreover, organoids constitute a tool with which to analyse how individual genetic variation contributes to the susceptibility and progression of neurodevelopmental disorders. This Roadmap article describes the features of brain organoids, focusing on the neocortex, and their advantages and limitations - in comparison with other model systems - for the study of brain development, evolution and disease. We highlight avenues for enhancing the physiological relevance of brain organoids by integrating bioengineering techniques and unbiased high-throughput analyses, and discuss future applications. As organoids advance in mimicking human brain functions, we address the ethical and societal implications of this technology.

Advancing autism research: Insights from brain organoid modeling

Autism Spectrum Disorders (ASD) are characterized by a variety of behavioral symptoms and a complex genetic architecture, posing significant challenges in understanding the mechanistic processes underlying their pathology. Despite extensive research, the mechanisms linking genetic variations to the phenotypic outcomes associated with ASD remain elusive. Consistent evidence indicates disruptions in early brain development among individuals with ASD. The advent of brain organoids offers a unique opportunity for uncovering, how brain development changes in ASD patients. Brain organoids are three-dimensional in vitro model systems derived from pluripotent stem cells that recapitulate early human brain development across multiple biological levels. They have become an invaluable tool for studying human-specific brain development processes and neurodevelopmental disorders. In this review, we discuss recent findings using brain organoid technologies to model ASD and discuss, how these new technologies can enhance our understanding of ASD genetics and pathology at the molecular, cellular, and tissue levels.

Cardiomyocyte sheet stacking using fibrin enables high-speed construction of three-dimensional myocardial tissue and high transplantation efficiency

Despite the development of three-dimensional (3D) tissues that promises remarkable advances in myocardial therapies and pharmaceutical research, vascularization is required for the repair of damaged hearts using cardiac tissue engineering. In this study, we developed a method for rapid generation of a 3D cardiac tissue, with extremely high engraftment efficiency, by stacking cardiomyocyte sheets using fibrin as an adhesive. Cell sheets were created by peeling off confluent cultured cells from a culture dish grafted with a polymer that induced surface hydrophilicity in response to low temperatures. The high engraftment rate was attributed to the retention of the adhesive protein. The multistacked vascularized cell sheets prepared using fibrin, when transplanted into the subcutaneous tissue and at myocardial infarction site in rats, yielded a transplanted 3D myocardial tissue. Furthermore, multilayered cardiomyocyte sheets were transplanted twice at 1 week intervals to create a 3D myocardial tissue. Our data suggest that fibrin-based rapidly layered cell sheets can advance tissue-engineered transplantation therapy and should aid the development of next-generation tissue-engineered products in the fields of regenerative medicine and drug screening.

Three-Dimensional-Bioprinted Embedded-Based Cerebral Organoids: An Alternative Approach for Mini-Brain In Vitro Modeling Beyond Conventional Generation Methods

Cerebral organoids (cORGs) obtained from induced pluripotent stem cells (iPSCs) have become significant instruments for investigating human neurophysiology, with the possibility of simulating diseases and enhancing drug discovery. The current approaches require a strict process of manual inclusion in animal-derived matrix Matrigel® and are challenged by unpredictability, operators' skill and expertise, elevated costs, and restricted scalability, impeding their extensive applicability and translational potential. In this study, we present a novel method to generate brain organoids that address these limitations. Our approach does not require a manual, operator-dependent embedding. Instead, it employs a chemically defined hydrogel in which the Matrigel® is diluted in a solution enriched with sodium alginate (SA) and sodium carboxymethylcellulose (CMC) and used as a bioink to print neural embryoid bodies (nEBs). Immunohistochemical, immunofluorescence, and gene expression analyses confirmed that SA-CMC-Matrigel® hydrogel can sustain the generation of iPSC-derived cortical cORGs as the conventional Matrigel®-based approach does. By day 40 of differentiation, hydrogel-based 3D-bioprinted cORGs showed heterogeneous and consistent masses, with a cytoarchitecture resembling an early-stage developmental fetal brain composed of neural progenitor cells PAX6+/Ki67+ organized into tubular structures, and densely packed cell somas with extensive neurites SYP+, suggestive of cortical tissue-like neuronal layer formation.

Individualized patient tumor organoids faithfully preserve human brain tumor ecosystems and predict patient response to therapy

Tumor organoids are important tools for cancer research, but current models have drawbacks that limit their applications for predicting response to therapy. Here, we developed a fast, efficient, and complex culture system (IPTO, individualized patient tumor organoid) that accurately recapitulates the cellular and molecular pathology of human brain tumors. Patient-derived tumor explants were cultured in induced pluripotent stem cell (iPSC)-derived cerebral organoids, thus enabling culture of a wide range of human tumors in the central nervous system (CNS), including adult, pediatric, and metastatic brain cancers. Histopathological, genomic, epigenomic, and single-cell RNA sequencing (scRNA-seq) analyses demonstrated that the IPTO model recapitulates cellular heterogeneity and molecular features of original tumors. Crucially, we showed that the IPTO model predicts patient-specific drug responses, including resistance mechanisms, in a prospective patient cohort. Collectively, the IPTO model represents a major breakthrough in preclinical modeling of human cancers, which provides a path toward personalized cancer therapy.

The potential of carbohydrate supramolecular hydrogels for long-term 3D culture of primary fibroblasts

N-Alkyl-galactonamides, which are small synthetic molecules derived from galactose, self-assemble to give fibrous hydrogels. These molecules are biocompatible and, in a previous study, the cell culture of human neural stem cells was performed for 7 days on a gel of N-heptyl-D-galactonamide. With the objective of broadening the scope of these molecules as scaffolds for cell culture, in the present study, the culture of primary human dermal fibroblasts has been carried out on N-nonyl-D-galactonamide hydrogels. These supramolecular fibrillar hydrogels have a sufficient mechanical strength to withstand cell culture (≈50 kPa) and they are resistant enough on the long term to carry out the cell culture over at least 3 weeks. In contrast to N-heptyl-D-galactonamide, N-nonyl-D-galactonamide is insoluble in the culture medium. It avoids its dissolution at each renewal of the culture medium. The molecule is only slowly eliminated by other mechanisms (1/3rd in 3 weeks), which did not impair the cell culture on a monthly scale. The hydrogel's microstructure and how the cells organize on this scaffold have been studied using electron and two-photon microscopies. The gel is made of a quite homogeneous network with a width of ≈180 nm and hundreds of micrometer long fibers, except at the surface where a dense mat of heterogeneous fibers is formed. We focused on methods able to colocalize the cells and the gel fibers. Many cell clusters have elongated and multidirectionnal shapes, guided by the fibers. Chains of single cells are also found following the fibers from one cluster to another. N-Nonyl-D-galactonamide fibers, which have the advantage of not being autofluorescent, do not mask the fluorescence of cells. But interestingly, they give a strong second harmonic generation (SHG) signal, due to their well-organized lamellar structure. We also made a special effort to visualize the penetration of cells within the depth of the hydrogels, in 3D, notably by sectioning the hydrogels, despite their softness. It was found that most of the cells stayed at the surface, but several cells grew within the supramolecular fiber network between 50 and 100 μm depth.

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.

Leptomeningeal Neural Organoid Fusions as Models to Study Meninges-Brain Signaling

Neural organoids derived from human-induced pluripotent stem cells (iPSCs) provide a model to study the earliest stages of human brain development, including neurogenesis, neural differentiation, and synaptogenesis. However, neural organoids lack supportive tissues and some non-neural cell types that are key regulators of brain development. Neural organoids have instead been cocultured with non-neural structures and cell types to promote their maturation and model interactions with neuronal cells. One component of the brain that does not form de novo in neural organoids is the meninges, a trilayered structure that surrounds the central nervous system and secretes key signaling molecules required for mammalian brain development. Most studies of meninges-brain signaling have been performed in mice or using two-dimensional cultures of human cells, which do not accurately recapitulate the architecture and cellular diversity of the tissue. To overcome this, we developed a coculture system of neural organoids generated from human iPSCs fused with fetal leptomeninges (LPM) from mice with fluorescently labeled meninges (Col1a1-GFP), which we call leptomeningeal neural organoid (LMNO) fusions. This proof-of-concept study tests the stability of the different cell types in the LPM (fibroblasts and macrophages) and the fused neural organoid (progenitors and neurons), as well as the interface between the organoid and meningeal tissue. We test the longevity of the fusion pieces after 30 and 60 days in culture, describe best practices for preparing the meninges sample before fusion, and examine the feasibility of single or multiple meninges pieces fused to a single organoid. We discuss potential uses of the current version of the LMNO fusion model and opportunities to improve the system.

Tissue-specific extracellular matrix for the larger-scaled expansion of spinal cord organoids

Spinal cord organoids (SCOs) are in vitro models that faithfully recapitulate the basic tissue architecture and cell types of the spinal cord and play a crucial role in developmental studies, disease modeling, and drug screening. Physiological cues are required for proliferation and differentiation during SCO culture. However, commonly used basement membrane matrix products, such as Matrigel®, lack tissue-specific biophysical signals. The current study utilizes decellularization process to fabricate tissue-derived hydrogel from porcine spinal cord tissue that retain intrinsic matrix components. This gel system supported an expanded neuroepithelial scale and enhanced ventral recognition patterns during SCO cultivation. Based on the characteristics of the enlarged aggregate size, a technical system for SCO cutting and subculture are proposed to improve the economic feasibility. Finally, the advantage of S-gel in maintaining neurite outgrowth are also found, which suggests its potential application in neural-related microphysiological systems.

Early spinal cord development: from neural tube formation to neurogenesis

As one of the simplest and most evolutionarily conserved parts of the vertebrate nervous system, the spinal cord serves as a key model for understanding the principles of nervous system construction. During embryonic development, the spinal cord originates from a population of bipotent stem cells termed neuromesodermal progenitors, which are organized within a transient embryonic structure known as the neural tube. Neural tube morphogenesis differs along its anterior-to-posterior axis: most of the neural tube (including the regions that will develop into the brain and the anterior spinal cord) forms via the bending and dorsal fusion of the neural groove, but the establishment of the posterior region of the neural tube involves de novo formation of a lumen within a solid medullary cord. The early spinal cord primordium consists of highly polarized neural progenitor cells organized into a pseudostratified epithelium. Tight regulation of the cell division modes of these progenitors drives the embryonic growth of the neural tube and initiates primary neurogenesis. A rich history of observational and functional studies across various vertebrate models has advanced our understanding of the cellular events underlying spinal cord development, and these foundational studies are beginning to inform our knowledge of human spinal cord development.

Bioengineering tools for next-generation neural organoids

Human stem cell-derived neural organoids were recently introduced as powerful in vitro 3D experimental model systems that innately undergo critical steps of organogenesis in culture and exhibit molecular, cellular, and structural features similar to the fetal human nervous system. These organoids have yielded new insights into human neurodevelopment and associated disorders. However, neural organoids have some crucial limitations that arise from the loosely controlled conditions for their development, an inability to maintain their spatial orientation in culture and a lack of technologies for taking long-term measurements on their morphology and electrical activity. Here, we review recent progress in using bioengineering methods to improve neural organoid formation and analysis by leveraging microfabrication, biomaterials, 3D printing, and flexible electrodes. We discuss how the applications of each technique can help to address critical limitations with standard neural organoid models. We conclude with a perspective on future applications of bioengineered next-generation neural organoids.

Organoids-on-a-chip: microfluidic technology enables culture of organoids with enhanced tissue function and potential for disease modeling

Organoids are stem-cell derived tissue structures mimicking specific structural and functional characteristics of human organs. Despite significant advancements in the field over the last decade, challenges like limited long-term functional culture and lack of maturation are hampering the implementation of organoids in biomedical research. Culture of organoids in microfluidic chips is being used to tackle these challenges through dynamic and precise control over the organoid microenvironment. This review highlights the significant breakthroughs that have been made in the innovative field of "organoids-on-chip," demonstrating how these have contributed to advancing organoid models. We focus on the incorporation of organoids representative for various tissues into chips and discuss the latest findings in multi-organoids-on-chip approaches. Additionally, we examine current limitations and challenges of the field towards the development of reproducible organoids-on-chip systems. Finally, we discuss the potential of organoids-on-chip technology for both in vitro and in vivo applications.

Vascular network-inspired diffusible scaffolds for engineering functional midbrain organoids

Organoids, 3D organ-like tissue cultures derived from stem cells, show promising potential for developmental biology, drug discovery, and regenerative medicine. However, the function and phenotype of current organoids, especially neural organoids, are still limited by insufficient diffusion of oxygen, nutrients, metabolites, signaling molecules, and drugs. Herein, we present vascular network-inspired diffusible (VID) scaffolds to mimic physiological diffusion physics for generating functional organoids and phenotyping their drug response. Specifically, the VID scaffolds, 3D-printed meshed tubular channel networks, successfully engineer human midbrain organoids almost without necrosis and hypoxia in commonly used well plates. Compared with conventional organoids, these engineered organoids develop more physiologically relevant features and functions, including midbrain-specific identity, oxygen metabolism, neuronal maturation, and network activity. Moreover, these engineered organoids also better recapitulate pharmacological responses, such as neural activity changes to fentanyl exposure, compared with conventional organoids with significant diffusion limits. This platform may provide insights for organoid development and therapeutic innovation.

Assembly of glioblastoma tumoroids and cerebral organoids: a 3D in vitro model for tumor cell invasion

Glioblastoma (GBM) has a fatal prognosis because of its aggressive and invasive characteristics. Understanding the mechanism of invasion necessitates an elucidation of the relationship between tumor cells and the tumor microenvironment. However, there has been a scarcity of suitable models to investigate this. In this study, we established a glioblastoma-cerebral organoid assembloid (GCOA) model by co-culturing patient-derived GBM tumoroids and human cerebral organoids. Tumor cells from the tumoroids infiltrated the cerebral organoids, mimicking the invasive nature of the parental tumors. Using time-lapse imaging, various invasion patterns of cancer cells within cerebral organoids resembling a normal tissue milieu were monitored. Both single- and collective-cell invasion was captured in real-time. We also confirmed the formation of an intercellular tumor network and tumor-normal-cell interactions. Furthermore, the transcriptomic characterization of GCOAs revealed distinct features of invasive tumor cells. Overall, this study established the GCOA as a three-dimensional (3D) in vitro assembloid model to investigate invasion mechanisms and interactions between tumor cells and their microenvironment.

Aberrant choroid plexus formation drives the development of treatment-related brain toxicity

Brain tumors are commonly treated with radiotherapy, but the efficacy of the treatment is limited by its toxicity to the normal tissue including post-irradiation contrast enhanced lesions often linked to necrosis. The poorly understood mechanisms behind such brain lesions were studied using cerebral organoids. Here we show that irradiation of such organoids leads to dose-dependent growth retardation and formation of liquid-filled cavities but is not correlated with necrosis. Instead, the radiation-induced changes comprise of an enhancement of cortical hem markers, altered neuroepithelial stem cell differentiation, and an increase of ZO1+/AQP1+/CLDN3+-choroid plexus (CP)-like structures accompanied by an upregulation of IGF2 mRNA, known to be expressed in CP and cerebrospinal fluid. The altered differentiation is attributed to changes in the WNT/BMP signaling pathways. We conclude that aberrant CP formation can be involved in radiation-induced brain lesions providing additional strategies for possible countermeasures.

Mitochondrially Transcribed dsRNA Mediates Manganese-induced Neuroinflammation

Manganese (Mn) is an essential trace element required for various biological functions, but excessive Mn levels are neurotoxic and lead to significant health concerns. The mechanisms underlying Mn-induced neurotoxicity remain poorly understood. Neuropathological studies of affected brain regions reveal astrogliosis, and neuronal loss, along with evidence of neuroinflammation. Here, we present a novel Mn-dependent mechanism linking mitochondrial dysfunction to neuroinflammation. We found that Mn disrupts mitochondrial transcriptome processing, resulting in the accumulation of complementary RNAs that form double-stranded RNA (dsRNA). This dsRNA is released to the cytoplasm, where it activates cytosolic sensor pathways, triggering type I interferon responses and inflammatory cytokine production. This mechanism is present in 100-day human cerebral organoids, where Mn-induced inflammatory responses are observed predominantly in mature astrocytes. Similar effects were observed in vivo in a mouse model carrying mutations in the SLC30A10 gene, which results in Mn accumulation. These findings highlight a previously unrecognized role for mitochondrial dsRNA in Mn-induced neuroinflammation and provide insights into the molecular basis of manganism. We propose that this mitochondrial dsRNA-induced inflammatory pathway has broad implications in for neurodegenerative diseases caused by environmental or genetic insults.

Advancing Glioblastoma Research with Innovative Brain Organoid-Based Models

Glioblastoma (GBM) is a relatively rare but highly aggressive form of brain cancer characterized by rapid growth, invasiveness, and resistance to standard therapies. Despite significant progress in understanding its molecular and cellular mechanisms, GBM remains one of the most challenging cancers to treat due to its high heterogeneity and complex tumor microenvironment. To address these obstacles, researchers have employed a range of models, including in vitro cell cultures and in vivo animal models, but these often fail to replicate the complexity of GBM. As a result, there has been a growing focus on refining these models by incorporating human-origin cells, along with advanced genetic techniques and stem cell-based bioengineering approaches. In this context, a variety of GBM models based on brain organoids were developed and confirmed to be clinically relevant and are contributing to the advancement of GBM research at the preclinical level. This review explores the preparation and use of brain organoid-based models to deepen our understanding of GBM biology and to explore novel therapeutic approaches. These innovative models hold significant promise for improving our ability to study this deadly cancer and for advancing the development of more effective treatments.

Vaccine-induced T cell receptor T cell therapy targeting a glioblastoma stemness antigen

T cell receptor-engineered T cells (TCR-T) could be advantageous in glioblastoma by allowing safe and ubiquitous targeting of the glioblastoma-derived peptidome. Protein tyrosine phosphatase receptor type Z1 (PTPRZ1), is a clinically targetable glioblastoma antigen associated with glioblastoma cell stemness. Here, we identify a therapeutic HLA-A*02-restricted PTPRZ1-reactive TCR retrieved from a vaccinated glioblastoma patient. Single-cell sequencing of primary brain tumors shows PTPRZ1 overexpression in malignant cells, especially in glioblastoma stem cells (GSCs) and astrocyte-like cells. The validated vaccine-induced TCR recognizes the endogenously processed antigen without off-target cross-reactivity. PTPRZ1-specific TCR-T (PTPRZ1-TCR-T) kill target cells antigen-specifically, and in murine experimental brain tumors, their combined intravenous and intracerebroventricular administration is efficacious. PTPRZ1-TCR-T maintain stem cell memory phenotype in vitro and in vivo and lyse all examined HLA-A*02+ primary glioblastoma cell lines with a preference for GSCs and astrocyte-like cells. In summary, we demonstrate the proof of principle to employ TCR-T to treat glioblastoma.

Human cerebral organoids model tumor infiltration and migration supported by astrocytes in an autologous setting

Efforts to achieve precise and efficient tumor targeting of highly malignant brain tumors are constrained by the dearth of appropriate models to study the effects and potential side effects of radiation, chemotherapy, and immunotherapy on the most complex human organ, the brain. We established a cerebral organoid model of brain tumorigenesis in an autologous setting by overexpressing c-MYC as one of the most common oncogenes in brain tumors. GFP + /c-MYC high cells were isolated from tumor organoids and used in two different culture approaches: assembloids comprising of a normal cerebral organoid with a GFP + /c-MYC high tumor sphere and co-culture of cerebral organoid slices at air-liquid interface with GFP + /c-MYC high cells. GFP + /c-MYC high cells used in both approaches exhibited tumor-like properties, including overexpression of the c-MYC oncogene, high proliferative and invasive potential, and an immature phenotype as evidenced by increased expression of Ki-67, VIM, and CD133. Organoids and organoid slices served as suitable scaffolds for infiltrating tumor-like cells. Using our highly reproducible and powerful model system that allows long-term culture, we demonstrated that the migratory and infiltrative potential of tumor-like cells is shaped by the environment in which glia cells provide support to tumor-like cells.

Cellular Systems for Colorectal Stem Cancer Cell Research

Oncological diseases consistently occupy leading positions among the most life-threatening diseases, including in highly developed countries. At the same time, the second most common cause of cancer death is colorectal cancer. The current level of research shows that the development of effective therapy, in this case, requires a new grade of understanding processes during the emergence and development of a tumor. In particular, the concept of cancer stem cells that ensure the survival of chemoresistant cells capable of giving rise to new tumors is becoming widespread. To provide adequate conditions that reproduce natural processes typical for tumor development, approaches based on increasingly complex cellular systems are being improved. This review discusses the main strategies that allow for the study of the properties of tumor cells with an emphasis on colorectal cancer stem cells. The features of working with tumor cells and the advantages and disadvantages of 2D and 3D culture systems are considered.

Emerging approaches to enhance human brain organoid physiology

Brain organoids are important 3D models for studying human brain development, disease, and evolution. To overcome some of the existing limitations that affect organoid quality, reproducibility, characteristics, and in vivo resemblance, current efforts are directed to improve their physiological relevance by exploring different, yet interconnected, routes. In this review, these approaches and their latest developments are discussed, including stem cell optimization, refining morphogen administration strategies, altering the extracellular matrix (ECM) niche, and manipulating tissue architecture to mimic in vivo brain morphogenesis. Additionally, strategies to increase cell diversity and enhance organoid maturation, such as establishing co-cultures, assembloids, and organoid in vivo xenotransplantation, are reviewed. We explore how these various factors can be tuned and intermingled and speculate on future avenues towards even more physiologically-advanced brain organoids.

Functional Imaging Methods for Investigating 3D Choroid Plexus Organoids

The choroid plexus (ChP) is a vital brain structure that produces cerebrospinal fluid (CSF) and forms a selective barrier between the blood and CSF, essential for brain homeostasis. Composed of secretory epithelial cells, connective stroma, and a fenestrated vascular network, the ChP supports nutrient transport, immune surveillance, and the clearance of toxic by-products. Despite its significance in maintaining cerebral function, the mechanisms underlying its development and maturation remain poorly understood. Recent advancements, such as the creation of stem cell-derived three-dimensional (3D) ChP organoid model, provide a promising platform for studying these processes. The ChP organoid model replicates key developmental stages and functions of the ChP, including CSF secretion and barrier formation. Additionally, they offer unique opportunities to investigate the impacts of drugs, pathogens, and toxins on the blood-CSF barrier. This study highlights imaging techniques critical for the characterization and utilization of ChP organoids, illustrating their value in advancing our understanding of ChP biology and its role in health and disease.

Functional and Structural Improvement of Engineered Cardiac Microtissue Using Aligned Microfilaments Scaffold

To enhance therapeutic strategies for cardiovascular diseases, the development of more reliable in vitro preclinical systems is imperative. These models, crucial for disease modeling and drug testing, must accurately replicate the 3D architecture of native heart tissue. In this study, we engineered a scaffold with aligned poly(lactic-co-glycolic acid) (PLGA) microfilaments to induce cellular alignment in the engineered cardiac microtissue (ECMT). Consequently, the coculture of three cell types, including cardiac progenitor cells (CPC), human umbilical cord endothelial cells (HUVEC), and human foreskin fibroblasts (HFF), within this 3D scaffold significantly improved cellular alignment compared to the control. Additionally, cells in the ECMT exhibited a more uniaxial anisotropic and oriented cytoskeleton, characterized by immunostaining of F-actin. This approach not only enhanced cell structure and microtissue architecture but also improved functionality, evident in synchronized electrophysiological signals. Therefore, our engineered cardiac microtissue using this aligned microfilament scaffold (AMFS) holds great potential for pharmaceutical research and other biomedical applications.

Human iPSC-derived microglial cells protect neurons from neurodegeneration in long-term cultured adhesion brain organoids

Brain organoid models have greatly facilitated our understanding of human brain development and disease. However, key brain cell types, such as microglia, are lacking in most brain organoid models. Because microglia have been shown to play important roles in brain development and pathologies, attempts have been made to add microglia to brain organoids through co-culture. However, only short-term microglia-organoid co-cultures can be established, and it remains challenging to have long-lasting survival of microglia in organoids to mimic long-term residency of microglia in the brain. In this study, we developed an adhesion brain organoid (ABO) platform that allows prolonged culture of brain organoids (greater than a year). Moreover, the long-term (LT)-ABO system contains abundant astrocytes and can support prolonged survival and ramification of microglia. Furthermore, we showed that microglia in the LT-ABO could protect neurons from neurodegeneration by increasing synaptic density and reducing p-Tau level and cell death in the LT-ABO. Therefore, the microglia-containing LT-ABO platform generated in this study provides a promising human cellular model for studying neuron-glia and glia-glia interactions in brain development and the pathogenesis of neurodegenerative diseases such as Alzheimer's disease.

Advances in the Development and Application of Human Organoids: Techniques, Applications, and Future Perspectives

Organoids are three-dimensional (3D) cell cultures derived from human pluripotent stem cells or adult stem cells that recapitulate the cellular heterogeneity, structure, and function of human organs. These microstructures are invaluable for biomedical research due to their ability to closely mimic the complexity of native tissues while retaining human genetic material. This fidelity to native organ systems positions organoids as a powerful tool for advancing our understanding of human biology and for enhancing preclinical drug testing. Recent advancements have led to the successful development of a variety of organoid types, reflecting a broad range of human organs and tissues. This progress has expanded their application across several domains, including regenerative medicine, where organoids offer potential for tissue replacement and repair; disease modeling, which allows for the study of disease mechanisms and progression in a controlled environment; drug discovery and evaluation, where organoids provide a more accurate platform for testing drug efficacy and safety; and microecological research, where they contribute to understanding the interactions between microbes and host tissues. This review provides a comprehensive overview of the historical development of organoid technology, highlights the key achievements and ongoing challenges in the field, and discusses the current and emerging applications of organoids in both laboratory research and clinical practice.

Central nervous system vascularization in human embryos and neural organoids

In recent years, neural organoids derived from human pluripotent stem cells (hPSCs) have offered a transformative pre-clinical platform for understanding central nervous system (CNS) development, disease, drug effects, and toxicology. CNS vasculature plays an important role in all these scenarios; however, most published studies describe CNS organoids that lack a functional vasculature or demonstrate rudimentary incorporation of endothelial cells or blood vessel networks. Here, we review the existing knowledge of vascularization during the development of different CNS regions, including the brain, spinal cord, and retina, and compare it to vascularized CNS organoid models. We highlight several areas of contrast where further bioengineering innovation is needed and discuss potential applications of vascularized neural organoids in modeling human CNS development, physiology, and disease.

Reliability of high-quantity human brain organoids for modeling microcephaly, glioma invasion and drug screening

Brain organoids offer unprecedented insights into brain development and disease modeling and hold promise for drug screening. Significant hindrances, however, are morphological and cellular heterogeneity, inter-organoid size differences, cellular stress, and poor reproducibility. Here, we describe a method that reproducibly generates thousands of organoids across multiple hiPSC lines. These High Quantity brain organoids (Hi-Q brain organoids) exhibit reproducible cytoarchitecture, cell diversity, and functionality, are free from ectopically active cellular stress pathways, and allow cryopreservation and re-culturing. Patient-derived Hi-Q brain organoids recapitulate distinct forms of developmental defects: primary microcephaly due to a mutation in CDK5RAP2 and progeria-associated defects of Cockayne syndrome. Hi-Q brain organoids displayed a reproducible invasion pattern for a given patient-derived glioma cell line. This enabled a medium-throughput drug screen to identify Selumetinib and Fulvestrant, as inhibitors of glioma invasion in vivo. Thus, the Hi-Q approach can easily be adapted to reliably harness brain organoids' application for personalized neurogenetic disease modeling and drug discovery.

Pluripotent stem cell-derived organoids: A brief history of curiosity-led discoveries

Organoids are quickly becoming an accepted model for understanding human biology and disease. Pluripotent stem cells (PSC) provide a starting point for many organs and enable modeling of the embryonic development and maturation of such organs. The foundation of PSC-derived organoids can be found in elegant developmental studies demonstrating the remarkable ability of immature cells to undergo histogenesis even when taken out of the embryo context. PSC-organoids are an evolution of earlier methods such as embryoid bodies, taken to a new level with finer control and in some cases going beyond tissue histogenesis to organ-like morphogenesis. But many of the discoveries that led to organoids were not necessarily planned, but rather the result of inquisitive minds with freedom to explore. Protecting such curiosity-led research through flexible funding will be important going forward if we are to see further ground-breaking discoveries.

Biofunctionalized gelatin hydrogels support development and maturation of iPSC-derived cortical organoids

Human neural organoid models have become an important tool for studying neurobiology. However, improving the representativeness of neural cell populations in such organoids remains a major effort. In this work, we compared Matrigel, a commercially available matrix, to a neural cadherin (N-cadherin) peptide-functionalized gelatin methacryloyl hydrogel (termed GelMA-Cad) for culturing cortical neural organoids. We determined that peptide presentation can tune cell fate and diversity in gelatin-based matrices during differentiation. Of particular note, cortical organoids cultured in GelMA-Cad hydrogels mapped more closely to human fetal populations and produced neurons with more spontaneous excitatory postsynaptic currents relative to Matrigel. These results provide compelling evidence that matrix-tethered signaling peptides can influence neural organoid differentiation, opening an avenue to control stem cell fate. Moreover, outcomes from this work showcase the technical utility of GelMA-Cad as a simple and defined hydrogel alternative to Matrigel for neural organoid culture.

Progress in spinal cord organoid research: advancing understanding of neural development, disease modelling, and regenerative medicine

Stem cell-derived spinal cord organoids (SCOs) have revolutionised the study of spinal cord development and disease mechanisms, offering a three-dimensional model that recapitulates the complexity of native tissue. This review synthesises recent advancements in SCO technology, highlighting their role in modelling spinal cord morphogenesis and their application in neurodegenerative disease research. We discuss the methodological breakthroughs in inducing regional specification and cellular diversity within SCOs, which have enhanced their predictive ability for drug screening and their relevance in mimicking pathological conditions such as neurodegenerative diseases and neuromuscular disorders. Despite these strides, challenges in achieving vascularisation and mature neuronal integration persist. The future of SCOs lies in addressing these limitations, potentially leading to transformative impactions in regenerative medicine and therapeutic development.

Manufacturing Uniform Cerebral Organoids for Neurological Disease Modeling and Drug Evaluation

Human cerebral organoids are promising tools for investigating brain development and the pathogenesis underlying neurological disorders. To use organoids for drug effectiveness and safety screening, the organoids dispensed into each well must be prepared under precisely the same conditions as the cells. Despite decades of extensive research on approaches to improve organoid generation, various challenges remain, such as low yields and heterogeneity in size and differentiation both within and between batches. Here, we newly established uniform cerebral organoids (UCOs) derived from induced pluripotent stem cells by optimizing organoid size and performing real-time monitoring of telencephalic differentiation marker expression. These organoids exhibited morphological uniformity and consistent expression of FOXG1 during telencephalic differentiation, with high productivity. Moreover, UCOs faithfully recapitulated early corticogenesis, concomitant with the establishment of neuroepithelial populations, cortical plate neurons, and glial cells. Furthermore, UCOs systematically developed neural networks and exhibited both excitatory and inhibitory electrophysiological signals when exposed to neurotransmission blockers. Neurodevelopmental disease models derived from UCOs manifested neurite outgrowth defects, which could be ameliorated with targeted drug treatment. We propose UCOs as an advanced platform with low organoid variations and high reproducibility for modeling both brain development and neurological diseases.

Low-intensity ultrasound ameliorates brain organoid integration and rescues microcephaly deficits

Human brain organoids represent a remarkable platform for modelling neurological disorders and a promising brain repair approach. However, the effects of physical stimulation on their development and integration remain unclear. Here, we report that low-intensity ultrasound significantly increases neural progenitor cell proliferation and neuronal maturation in cortical organoids. Histological assays and single-cell gene expression analyses revealed that low-intensity ultrasound improves the neural development in cortical organoids. Following organoid grafts transplantation into the injured somatosensory cortices of adult mice, longitudinal electrophysiological recordings and histological assays revealed that ultrasound-treated organoid grafts undergo advanced maturation. They also exhibit enhanced pain-related gamma-band activity and more disseminated projections into the host brain than the untreated groups. Finally, low-intensity ultrasound ameliorates neuropathological deficits in a microcephaly brain organoid model. Hence, low-intensity ultrasound stimulation advances the development and integration of brain organoids, providing a strategy for treating neurodevelopmental disorders and repairing cortical damage.

Human brain organoid: trends, evolution, and remaining challenges

Advanced brain organoids provide promising platforms for deciphering the cellular and molecular processes of human neural development and diseases. Although various studies and reviews have described developments and advancements in brain organoids, few studies have comprehensively summarized and analyzed the global trends in this area of neuroscience. To identify and further facilitate the development of cerebral organoids, we utilized bibliometrics and visualization methods to analyze the global trends and evolution of brain organoids in the last 10 years. First, annual publications, countries/regions, organizations, journals, authors, co-citations, and keywords relating to brain organoids were identified. The hotspots in this field were also systematically identified. Subsequently, current applications for brain organoids in neuroscience, including human neural development, neural disorders, infectious diseases, regenerative medicine, drug discovery, and toxicity assessment studies, are comprehensively discussed. Towards that end, several considerations regarding the current challenges in brain organoid research and future strategies to advance neuroscience will be presented to further promote their application in neurological research.

A polarized FGF8 source specifies frontotemporal signatures in spatially oriented cell populations of cortical assembloids

Organoids generating major cortical cell types in distinct compartments are used to study cortical development, evolution and disorders. However, the lack of morphogen gradients imparting cortical positional information and topography in current systems hinders the investigation of complex phenotypes. Here, we engineer human cortical assembloids by fusing an organizer-like structure expressing fibroblast growth factor 8 (FGF8) with an elongated organoid to enable the controlled modulation of FGF8 signaling along the longitudinal organoid axis. These polarized cortical assembloids mount a position-dependent transcriptional program that in part matches the in vivo rostrocaudal gene expression patterns and that is lost upon mutation in the FGFR3 gene associated with temporal lobe malformations and intellectual disability. By producing spatially oriented cell populations with signatures related to frontal and temporal area identity within individual assembloids, this model recapitulates in part the early transcriptional divergence embedded in the protomap and enables the study of cortical area-relevant alterations underlying human disorders.

Non-small cell lung cancer organoids: Advances and challenges in current applications

Lung cancer is emerging as a common malignancy worldwide, with non-small cell lung cancer (NSCLC) accounting for approximately 85% of all cases. Two-dimensional (2D) in vitro cell line cultures and animal models are currently used to study NSCLC. However, 2D cell cultures fail to replicate the medication response and neoplastic heterogeneity of parental tumors. Animal models are expensive and require lengthy modeling cycles. The generation of in vitro three-dimensional (3D) tissue cultures called organoids, which exhibit multicellular, anatomical, and functional properties of real organs, is now achievable owing to advancements in stem cell culturing. The genetic, proteomic, morphological, and pharmacological characteristics of tumors are largely preserved in tumor organoids grown in vitro. The design and physiology of human organs can be precisely reconstructed in tumor organoids, opening new possibilities for complementing the use of animal models and studying human diseases. This review summarizes the development of NSCLC organoids and their applications in basic research, drug testing, immunotherapy, and individualized treatments.

Dynamic culture of cerebral organoids using a pillar/perfusion plate for the assessment of developmental neurotoxicity

Despite the potential toxicity of commercial chemicals to the development of the nervous system (known as developmental neurotoxicity or DNT), conventionalin vitrocell models have primarily been employed for the assessment of acute neuronal toxicity. On the other hand, animal models used for the assessment of DNT are not physiologically relevant due to the heterogenic difference between humans and animals. In addition, animal models are low-throughput, time-consuming, expensive, and ethically questionable. Recently, human brain organoids have emerged as a promising alternative to assess the detrimental effects of chemicals on the developing brain. However, conventional organoid culture systems have several technical limitations including low throughput, lack of reproducibility, insufficient maturity of organoids, and the formation of the necrotic core due to limited diffusion of nutrients and oxygen. To address these issues and establish predictive DNT models, cerebral organoids were differentiated in a dynamic condition in a unique pillar/perfusion plate, which were exposed to test compounds to evaluate DNT potential. The pillar/perfusion plate facilitated uniform, dynamic culture of cerebral organoids with improved proliferation and maturity by rapid, bidirectional flow generated on a digital rocker. Day 9 cerebral organoids in the pillar/perfusion plate were exposed to ascorbic acid (DNT negative) and methylmercury (DNT positive) in a dynamic condition for 1 and 3 weeks, and changes in organoid morphology and neural gene expression were measured to determine DNT potential. As expected, ascorbic acid did not induce any changes in organoid morphology and neural gene expression. However, exposure of day 9 cerebral organoids to methylmercury resulted in significant changes in organoid morphology and neural gene expression. Interestingly, methylmercury did not induce adverse changes in cerebral organoids in a static condition, thus highlighting the importance of dynamic organoid culture in DNT assessment.

Progress and potential of brain organoids in epilepsy research

Epilepsies are disorders of the brain characterised by an imbalance in electrical activity, linked to a disruption in the excitation and inhibition of neurons. Progress in the epilepsy research field has been hindered by the lack of an appropriate model, with traditionally used 2D primary cell culture assays and animal models having a number of limitations which inhibit their ability to recapitulate the developing brain and the mechanisms behind epileptogenesis. As a result, the mechanisms behind the pathogenesis of epilepsy are largely unknown. Brain organoids are 3D aggregates of neural tissue formed in vitro and have been shown to recapitulate the gene expression patterns of the brain during development, and can successfully model a range of epilepsies and drug responses. They thus present themselves as a novel tool to advance studies into epileptogenesis. In this review, we discuss the formation of brain organoids, their recent application in studying genetic epilepsies, hyperexcitability dynamics and oxygen glucose deprivation as a hyperexcitability agent, their use as an epilepsy drug testing and development platform, as well as the limitations of their use in epilepsy research and how these can be mitigated.

Human olfactory neurosphere-derived cells: a unified tool for neurological disease modelling and neurotherapeutic applications

As one of the leading causes of global mortality and morbidity, various neurological diseases cause social and economic burdens. Despite significant advances in the treatment of neurological diseases, establishing a proper disease model, especially for degenerative and infectious diseases, remains a major challenging issue. For long, mice were the model of choice but suffered from serious drawbacks of differences in anatomical and functional aspects of the nervous system. Furthermore, the collection of postmortem brain tissues limits their usage in cultured cell lines. Overcoming such limitations has prompted the usage of stem cells derived from the peripheral nervous system, such as the cells of the olfactory mucosa as a preferred choice. These cells can be easily cultured in vitro and retain the receptors of neuronal cells life-long. Such cells have various advantages over embryonic or induced stem cells, including homology, and ease of culture and can be conveniently obtained from diseased individuals through either biopsies or exfoliation. They have continuously helped in understanding the genetic and developmental mechanisms of degenerative diseases like Alzheimer's and Parkinson's disease. Moreover, the mode of infection of various viruses that can lead to postviral olfactory dysfunction, such as the Zika virus can be monitored through these cells in vitro and their therapeutic development can be fastened.

Advances in the Differentiation of hiPSCs into Cerebellar Neuronal Cells

The cerebellum has historically been primarily associated with the regulation of precise motor functions. However, recent findings suggest that it also plays a pivotal role in the development of advanced cognitive functions, including learning, memory, and emotion regulation. Pathological changes in the cerebellum, whether congenital hereditary or acquired degenerative, can result in a diverse spectrum of disorders, ranging from genetic spinocerebellar ataxias to psychiatric conditions such as autism, and schizophrenia. While studies in animal models have significantly contributed to our understanding of the genetic networks governing cerebellar development, it is important to note that the human cerebellum follows a protracted developmental timeline compared to the neocortex. Consequently, employing animal models to uncover human-specific molecular events in cerebellar development presents significant challenges. The emergence of human induced pluripotent stem cells (hiPSCs) has provided an invaluable tool for creating human-based culture systems, enabling the modeling and analysis of cerebellar physiology and pathology. hiPSCs and their differentiated progenies can be derived from patients with specific disorders or carrying distinct genetic variants. Importantly, they preserve the unique genetic signatures of the individuals from whom they originate, allowing for the elucidation of human-specific molecular and cellular processes involved in cerebellar development and related disorders. This review focuses on the technical advancements in the utilization of hiPSCs for the generation of both 2D cerebellar neuronal cells and 3D cerebellar organoids.

Functional Neural Networks in Human Brain Organoids

Human brain organoids are 3-dimensional brain-like tissues derived from human pluripotent stem cells and hold promising potential for modeling neurological, psychiatric, and developmental disorders. While the molecular and cellular aspects of human brain organoids have been intensively studied, their functional properties such as organoid neural networks (ONNs) are largely understudied. Here, we summarize recent research advances in understanding, characterization, and application of functional ONNs in human brain organoids. We first discuss the formation of ONNs and follow up with characterization strategies including microelectrode array (MEA) technology and calcium imaging. Moreover, we highlight recent studies utilizing ONNs to investigate neurological diseases such as Rett syndrome and Alzheimer's disease. Finally, we provide our perspectives on the future challenges and opportunities for using ONNs in basic research and translational applications.

Cross-site reproducibility of human cortical organoids reveals consistent cell type composition and architecture

While guided human cortical organoid (hCO) protocols reproducibly generate cortical cell types at one site, variability in hCO phenotypes across sites using a harmonized protocol has not yet been evaluated. To determine the cross-site reproducibility of hCO differentiation, three independent research groups assayed hCOs in multiple differentiation replicates from one induced pluripotent stem cell (iPSC) line using a harmonized miniaturized spinning bioreactor protocol across 3 months. hCOs were mostly cortical progenitor and neuronal cell types in reproducible proportions that were consistently organized in cortical wall-like buds. Cross-site differences were detected in hCO size and expression of metabolism and cellular stress genes. Variability in hCO phenotypes correlated with stem cell gene expression prior to differentiation and technical factors associated with seeding, suggesting iPSC quality and treatment are important for differentiation outcomes. Cross-site reproducibility of hCO cell type proportions and organization encourages future prospective meta-analytic studies modeling neurodevelopmental disorders in hCOs.

Vascular network-inspired diffusible scaffolds for engineering functional neural organoids

Organoids, three-dimensional in vitro organ-like tissue cultures derived from stem cells, show promising potential for developmental biology, drug discovery, and regenerative medicine. However, the function and phenotype of current organoids, especially neural organoids, are still limited by insufficient diffusion of oxygen, nutrients, metabolites, signaling molecules, and drugs. Herein, we present Vascular network-Inspired Diffusible (VID) scaffolds to fully recapture the benefits of physiological diffusion physics for generating functional organoids and phenotyping their drug response. In a proof-of-concept application, the VID scaffolds, 3D-printed meshed tubular channel networks, support the successful generation of engineered human midbrain organoids almost without necrosis and hypoxia in commonly used well-plates. Compared to conventional organoids, these engineered organoids develop with more physiologically relevant features and functions including midbrain-specific identity, oxygen metabolism, neuronal maturation, and network activity. Moreover, these engineered organoids also better recapitulate pharmacological responses, such as neural activity changes to fentanyl exposure, compared to conventional organoids with significant diffusion limits. Combining these unique scaffolds and engineered organoids may provide insights for organoid development and therapeutic innovation.

Particle Beam Radiobiology Status and Challenges: A PTCOG Radiobiology Subcommittee Report

Particle therapy (PT) represents a significant advancement in cancer treatment, precisely targeting tumor cells while sparing surrounding healthy tissues thanks to the unique depth-dose profiles of the charged particles. Furthermore, their linear energy transfer and relative biological effectiveness enhance their capability to treat radioresistant tumors, including hypoxic ones. Over the years, extensive research has paved the way for PT's clinical application, and current efforts aim to refine its efficacy and precision, minimizing the toxicities. In this regard, radiobiology research is evolving toward integrating biotechnology to advance drug discovery and radiation therapy optimization. This shift from basic radiobiology to understanding the molecular mechanisms of PT aims to expand the therapeutic window through innovative dose delivery regimens and combined therapy approaches. This review, written by over 30 contributors from various countries, provides a comprehensive look at key research areas and new developments in PT radiobiology, emphasizing the innovations and techniques transforming the field, ranging from the radiobiology of new irradiation modalities to multimodal radiation therapy and modeling efforts. We highlight both advancements and knowledge gaps, with the aim of improving the understanding and application of PT in oncology.

Brain organoids: A new tool for modelling of neurodevelopmental disorders

Neurodevelopmental disorders are mostly studied using mice as models. However, the mouse brain lacks similar cell types and structures as those of the human brain. In recent years, emergence of three-dimensional brain organoids derived from human embryonic stem cells or induced pluripotent stem cells allows for controlled monitoring and evaluation of early neurodevelopmental processes and has opened a window for studying various aspects of human brain development. However, such organoids lack original anatomical structure of the brain during maturation, and neurodevelopmental maturation processes that rely on unique cellular interactions and neural network connections are limited. Consequently, organoids are difficult to be used extensively and effectively while modelling later stages of human brain development and disease progression. To address this problem, several methods and technologies have emerged that aim to enhance the sophisticated regulation of brain organoids developmental processes through bioengineering approaches, which may alleviate some of the current limitations. This review discusses recent advances and application areas of human brain organoid culture methods, aiming to generalize optimization strategies for organoid systems, improve the ability to mimic human brain development, and enhance the application value of organoids.

A comprehensive review of electrophysiological techniques in amyotrophic lateral sclerosis research

Amyotrophic lateral sclerosis (ALS), a devastating neurodegenerative disease, is characterized by progressive motor neuron degeneration, leading to widespread weakness and respiratory failure. While a variety of mechanisms have been proposed as causes of this disease, a full understanding remains elusive. Electrophysiological alterations, including increased motor axon excitability, likely play an important role in disease progression. There remains a critical need for non-animal disease models that can integrate electrophysiological tools to better understand underlying mechanisms, track disease progression, and evaluate potential therapeutic interventions. This review explores the integration of electrophysiological technologies with ALS disease models. It covers cellular and clinical electrophysiological tools and their applications in ALS research. Additionally, we examine conventional animal models and highlight advancements in humanized models and 3D organoid technologies. By bridging the gap between these models, we aim to enhance our understanding of ALS pathogenesis and facilitate the development of new therapeutic strategies.

Establishment of advanced tumor organoids with emerging innovative technologies

Tumor organoids have emerged as a crucial preclinical model for multiple cancer research. Their high establishment rates, stability, and ability to replicate key biological features of original tumor cells in vivo render them invaluable for exploring tumor molecular mechanisms, discovering potential anti-tumor drugs, and predicting clinical drug efficacy. Here, we review the establishment of tumor organoid models and provide an extensive overview of organoid culturing strategies. We also emphasize the significance of integrating cellular components of the tumor microenvironment and physicochemical factors in the organoid culturing system, highlighting the importance of artificial intelligence technology in advancing organoid construction. Moreover, we summarize recent advancements in utilizing organoid systems for novel anti-cancer drug screening and discuss promising trends for enhancing advanced organoids in next-generation disease modeling.

Research progress of brain organoids in the field of diabetes

Human embryonic stem cells and human induced pluripotent stem cells may be used to create 3D tissues called brain organoids. They duplicate the physiological and pathological characteristics of human brain tissue more faithfully in terms of both structure and function, and they more precisely resemble the morphology and cellular structure of the human embryonic brain. This makes them valuable models for both drug screening and in vitro studies on the development of the human brain and associated disorders. The technical breakthroughs enabled by brain organoids have a significant impact on the research of different brain regions, brain development and sickness, the connections between the brain and other tissues and organs, and brain evolution. This article discusses the development of brain organoids, their use in diabetes research, and their progress.

Is Tunisia ready for precision medicine? Challenges of medical genomics within a LMIC healthcare system

As one of the key tools on the precision medicine workbench, high-throughput genetic testing has enormous promise for improving healthcare outcomes. Tunisia has made tremendous progress in acquiring and implementing the technology in the clinical context. However, current utilization does not ensure the whole range of benefits that high-throughput genomic testing provides which impedes the country's ability to move forward into the new era of precision medicine. This issue is primarily related to the current state of Tunisia's healthcare ecosystem and the sociological attributes of its population, creating numerous challenges that must be addressed. In the current review, we aimed to identify and highlight these challenges that may be prevalent in other low and middle-income countries. Essentially, they fall into three main categories that include the socio-economic landscape in Tunisia, which prevents citizens from engaging in precision medicine activities; the current settings of the healthcare system that lack or miss key components for the successful implementation of precision medicine practices; and the inability of the current infrastructure and resources to handle the various challenges related to genomic data and metadata. We also propose five pillar solutions as a framework for addressing all of these challenges, which could strengthen Tunisia's capability for effective precision medicine implementation in today's clinical environment.