Tissue morphology influences the temporal program of human brain organoid development

The unveiled mosaic of intra-tumor heterogeneity in ovarian cancer through spatial transcriptomic technologies: A systematic review

Epithelial ovarian cancer is a significant global health issue among women. Diagnosis and treatment pose challenges due to difficulties in predicting patient responses to therapy, primarily stemming from gaps in understanding tumor chemoresistance mechanisms. Recent advancements in transcriptomic technologies like single-cell RNA sequencing and spatial transcriptomics have greatly improved our understanding of ovarian cancer intratumor heterogeneity and tumor microenvironment composition. Spatial transcriptomics, in particular, comprises a plethora of technologies that enable the detection of hundreds of transcriptomes and their spatial distribution within a histological section, facilitating the study of cell types, states, and interactions within the tumor and its microenvironment. Studies investigating the spatial distribution of gene expression in ovarian cancer masses have identified specific features that impact prognosis and therapy outcomes. Emerging evidence suggests that specific spatial patterns of tumor cells and their immune and non-immune microenvironment significantly influence therapy response, as well as the behavior and progression of primary tumors and metastatic sites. The importance of spatially contextualizing ovarian cancer transcriptomes is underscored by these findings, which will advance our understanding and therapeutic approaches for this complex disease.

Artificial Meshed Vessel-Induced Dimensional Breaking Growth of Human Brain Organoids and Multiregional Assembloids

Brain organoids are widely used to model brain development and diseases. However, a major challenge in their application is the insufficient supply of oxygen and nutrients to the core region, restricting the size and maturation of the organoids. In order to vascularize brain organoids and enhance the nutritional supply to their core areas, two-photon polymerization (TPP) 3D printing is employed to fabricate high-resolution meshed vessels in this study. These vessels made of photoresist with densely distributed micropores with a diameter of 20 μm on the sidewall, are cocultured with brain organoids to facilitate the diffusion of culture medium into the organoids. The vascularized organoids exhibit dimensional breaking growth and enhanced proliferation, reduced hypoxia and apoptosis, suggesting that the 3D-printed meshed vessels partially mimic vascular function to promote the culture of organoids. Furthermore, cortical, striatal and medial ganglionic eminence (MGE) organoids are respectively differentiated to generate Cortico-Striatal-MGE assembloids by 3D-printed vessels. The enhanced migration, projection and excitatory signaling transduction are observed between different brain regional organoids in the assembloids. This study presents an approach using TPP 3D printing to construct vascularized brain organoids and assembloids for enhancing the development and assembly, offering a research model and platform for neurological diseases.

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.

Primitive and Definitive Neural Precursor Cells Are Present in Human Cerebral Organoids

Activation of neural stem cells (NSCs) correlates with improved functional outcomes in mouse models of injury. In the murine brain, NSCs have been extensively characterized and comprise (1) primitive NSCs (pNSCs) and (2) definitive NSCs (dNSCs). pNSCs are the earliest cells in the NSC lineage giving rise to dNSCs in the embryonic and adult mouse brain. pNSCs are quiescent under baseline conditions and can be activated upon injury. Herein, we asked whether human pNSCs and dNSCs can be isolated during the maturation of human cerebral organoids (COs) and activated by drugs known to regulate mouse NSC behavior. We demonstrate that self-renewing, multipotent pNSC and dNSC populations are present in human COs and express genes previously characterized in mouse NSCs. The drug NWL283, an inhibitor of apoptosis, reduced cell death in COs but did not improve NSC survival. Metformin, a drug used to treat type II diabetes that is known to promote NSC activation in mice, was found to expand human NSC pools. Together, these findings are the first to identify and characterize human pNSCs, advancing our understanding of the human NSC lineage and highlighting drugs that enhance their activity.

Rigor and reproducibility in human brain organoid research: Where we are and where we need to go

Human brain organoid models have emerged as a promising tool for studying human brain development and function. These models preserve human genetics and recapitulate some aspects of human brain development, while facilitating manipulation in an in vitro setting. Despite their potential to transform biology and medicine, concerns persist about their fidelity. To fully harness their potential, it is imperative to establish reliable analytic methods, ensuring rigor and reproducibility. Here, we review current analytical platforms used to characterize human forebrain cortical organoids, highlight challenges, and propose recommendations for future studies to achieve greater precision and uniformity across laboratories.

Modeling hypothalamic pathophysiology in vitro for metabolic, circadian, and sleep disorders

The hypothalamus, a small and intricate brain structure, orchestrates numerous neuroendocrine functions through specialized neurons and nuclei. Disruption of this complex circuitry can result in various diseases, including metabolic, circadian, and sleep disorders. Advances in in vitro models and their integration with new technologies have significantly benefited research on hypothalamic function and pathophysiology. We explore existing in vitro hypothalamic models and address their challenges and limitations as well as translational findings. We also highlight how collaborative efforts among multidisciplinary teams are essential to develop relevant and translational experimental models capable of replicating intricate neural circuits and neuroendocrine pathways, thereby advancing our understanding of therapeutic targets and drug discovery in hypothalamus-related disorders.

Brain organoid protocols and limitations

Stem cell-derived organoid technology is a powerful tool that revolutionizes the field of biomedical research and extends the scope of our understanding of human biology and diseases. Brain organoids especially open an opportunity for human brain research and modeling many human neurological diseases, which have lagged due to the inaccessibility of human brain samples and lack of similarity with other animal models. Brain organoids can be generated through various protocols and mimic whole brain or region-specific. To provide an overview of brain organoid technology, we summarize currently available protocols and list several factors to consider before choosing protocols. We also outline the limitations of current protocols and challenges that need to be solved in future investigation of brain development and pathobiology.

Moral considerability of brain organoids from the perspective of computational architecture

Human brain organoids equipped with complex cytoarchitecture and closed-loop feedback from virtual environments could provide insights into neural mechanisms underlying cognition. Yet organoids with certain cognitive capacities might also merit moral consideration. A precautionary approach has been proposed to address these ethical concerns by focusing on the epistemological question of whether organoids possess neural structures for morally-relevant capacities that bear resemblance to those found in human brains. Critics challenge this similarity approach on philosophical, scientific, and practical grounds but do so without a suitable alternative. Here, I introduce an architectural approach that infers the potential for cognitive-like processing in brain organoids based on the pattern of information flow through the system. The kind of computational architecture acquired by an organoid then informs the kind of cognitive capacities that could, theoretically, be supported and empirically investigated. The implications of this approach for the moral considerability of brain organoids are discussed.