Regional specificity of brain organoids and their application in ischemic stroke modeling and drug development

Abstract

BACKGROUND: The construction of brain organoid technology and its application in ischemic stroke are new research hotspots in recent years. The anatomy and functional organization of the brain of rodents are significantly different from those of the human brain, which determines that they cannot fully mimic the physiological, pathological and anatomical characteristics of the human brain. At the same time, there are ethical issues in obtaining brain tissue samples from patients in clinical practice, so the importance of brain organoids in ischemic stroke research lies in their ability to replace clinical brain tissue and animal models to construct in vitro research models that are more closely related to human brain tissue, and they are of great value in disease mechanism modeling and drug development. OBJECTIVE: To review and summarize the current research on regional specificity of brain organoids, and to provide new technical means and research strategies for the application of brain organoids in ischemic stroke modeling and drug development. METHODS: Literature search on organoids and ischemic stroke was conducted in CNKI and PubMed databases, with the search time limit from database inception to May 2025. Chinese search terms were "ischemic stroke, stroke, organoids, ischemia-reperfusion injury, oxygen-glucose deprivation/reoxygenation, forebrain organoids, hippocampal organoids, thalamic organoids, midbrain organoids", and English search terms were "ischemic stroke, stroke, organoids, oxygen-glucose deprivation/reoxygenation, middle cerebral artery occlusion, forebrain organoids, hippocampal organoids, thalamic organoids, midbrain organoids". All retrieved literature included original research and related reviews, and finally 98 articles were screened for analysis and summary. RESULTS AND CONCLUSION: (1) Dorsal forebrain organoids mimic cortical neuroepithelium and differentiate into neural cells such as astrocytes, excitatory neurons, and oligodendrocytes; ventral forebrain organoids mimic ganglionic eminences and develop into basal ganglia and striatum, exhibiting extensive neuronal migration and maintaining GABAergic properties. (2) Human induced pluripotent stem cell-derived hippocampal organoids can integrate functionally with mouse hippocampal neural circuits, receive excitatory input, and form synaptic-connected neuronal networks. (3) Thalamic/hypothalamic organoids mimic the development and cellular diversity of the human hypothalamic arcuate nucleus and explore dopaminergic neuron specificity. (4) Midbrain organoids are widely used in modeling Parkinson's disease, gene editing, and drug development. (5) Oxygen-glucose deprivation can induce brain organoids to simulate ischemic stroke in vitro, and then participate in neural injury through apoptosis, necroptosis, autophagy, and ferroptosis. The gene expression profile of brain organoids after oxygen-glucose deprivation changes significantly. Application of neuroprotective drugs such as carnosic acid or transplantation of brain organoids into rats with middle cerebral artery occlusion can improve neurological deficits and reduce infarct volume, playing an important role in transplantation regenerative medicine.

1. Introduction

Ischemic stroke, caused by arterial occlusion leading to reduced blood flow, results in severe consequences such as facial paralysis, limb movement disorders, head deviation, and aphasia, causing tremendous harm to patients' daily life and health [1-2]. Therefore, the development of therapeutic drugs for ischemic stroke is urgent. Over the past decades, many neuroprotective agents targeting excitotoxicity, oxidative stress, nitrosative stress, and inflammation have been developed, but almost all are in the transition from laboratory to clinical use [3]. One major factor is the species difference between experimental and clinical studies. In the laboratory, research on neuroprotective agents for stroke is mainly conducted on rodent models, not on primate or humanized models, which may mislead clinical efficacy to some extent. Compared with humans, rodents are lissencephalic, with smooth cortices and no sulci [4], and their white matter proportion is lower than that of the human brain. The proportion of white matter in the whole brain is 60% in humans, 15% in rats, and 10% in mice [5]. The degree of ischemic injury to white matter plays a crucial role in stroke prognosis. These differences determine that they cannot fully mimic the physiological, pathological, and anatomical characteristics of the human brain. Currently, whether the lissencephalic structure of rats affects the efficacy of stroke therapeutic drugs remains controversial, but it is certain that different anatomical structures and functional organizations are related to infarct location. Therefore, how to establish a stroke research model that better conforms to human brain physiology and function has been a challenge in the development of effective anti-stroke drugs.

Meanwhile, due to significant limitations in obtaining tissue samples from patients with brain diseases, research on brain diseases mainly relies on animal models. Due to species differences, the results of animal experiments often cannot be directly translated to humans. Brain organoids, derived from stem cells, are three-dimensional cell clusters that self-organize and mimic the structure and function of organs in vitro. They have emerged as a promising alternative to animal models and human brain tissue, providing a more physiologically relevant platform for disease modeling and drug testing. In the context of ischemic stroke, brain organoids with regional specificity—such as forebrain, hippocampal, thalamic, and midbrain organoids—can recapitulate the complex cellular architecture and regional vulnerability of the human brain, offering new opportunities for understanding disease mechanisms and developing effective therapies.