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challenges, particularly in terms of reproducibility and ranging from molecular dysregulation to neural circuit
long-term viability. Although BOs derived from diverse remodeling. Although the human brain represents the most
human-induced pluripotent stem cell (hiPSC) lines exhibit physiologically relevant model, direct experimentation is
consistent cellular diversity and developmental trajectories, constrained by both technical limitations in maintaining
achieving uniform reproducibility across laboratories functional neural networks ex vivo and ethical restrictions
remains a formidable task. Data indicate that 95% of BOs on invasive human brain research. While animal models
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generate virtually indistinguishable cell types, highlighting have provided valuable insights into conserved biological
the highly constrained and reproducible nature of cellular pathways, their translational relevance is limited by inherent
diversity irrespective of the hiPSC line origin. While BOs can interspecies differences in cortical cytoarchitecture,
be maintained in culture for up to 6 months with preserved neuroimmune interactions, and blood–brain barrier (BBB)
cellular integrity, addressing cellular senescence and dynamics. These limitations hinder their ability to reliably
differentiation arrest is essential for broader applicability. model higher-order cognitive impairments and predict
The necessity for standardized protocols and stringent human-specific therapeutic responses.
quality control measures, such as spinner-flask bioreactor The development of human BO systems has emerged
culturing and single-cell RNA sequencing validation, is as a transformative approach, enabling the generation
underscored to ensure consistency and reliability in BOs of patient-derived 3D neural tissues that retain disease-
research. 6-10
specific genetic and phenotypic features. However, this
This review systematically examines the application of innovative technology also introduces ethical challenges,
BOs in neurosurgical practice, with a specific focus on their particularly concerning stem cell provenance validation
utility in modeling three critical neurological conditions: and neural activity monitoring, as emphasized in the
traumatic brain injury (TBI), glioblastoma (GBM), and ISSCR 2021 guidelines. Addressing these challenges is
Parkinson’s disease (PD). As three-dimensional (3D) in vitro critical to advancing the field while maintaining rigorous
models that replicate key aspects of the human brain’s ethical standards.
complexity, BOs have become essential tools for studying
CNS disorders. In TBI research, BOs effectively model 2.2. Advances in in vivo and ex vivo models
both acute and chronic pathological effects, including Human embryonic stem cells (hESCs) have emerged as
neuronal death and neuroinflammation processes. 11-13 a pivotal tool in the study of CNS diseases within ex vivo
For brain tumor investigations, particularly GBM, BOs models. Derived from the pluripotent inner cell mass
provide unique insights into the tumor microenvironment of pre-implantation blastocysts, these cells possess the
(TME) and GSCs behavior, significantly contributing capability to self-renew and differentiate into all three
to therapeutic strategy development. 14-16 In PD studies, germ layers, including various cell lineages within the
BOs serve as valuable platforms for investigating the CNS. By controlling the differentiation of these cells
characteristic loss of dopaminergic neurons and protein in vitro, researchers can simulate the complex processes
misfolding mechanisms. 17-20 From a fundamental research of CNS development and disease progression. Through
standpoint, these sophisticated in vitro models provide technological advancements, hESCs have evolved to
unprecedented insights into disease pathogenesis and become an essential tool for studying brain development
progression, thereby potentially guiding the development and dysfunction, thus advancing basic research into
of innovative surgical interventions and personalized neurological disorders. However, the use of hESCs is
therapeutic strategies. However, the broader application still encumbered by ethical concerns, which limit their
of BOs in drug development and regenerative medicine widespread application.
faces significant challenges, particularly in standardizing
production protocols and maintaining long-term culture The development of hiPSCs offers a promising alternative
stability. The primary objective of this review is to to address the issues associated with traditional neural
establish a comprehensive reference framework for both system modeling. By reprogramming human fibroblasts
clinicians and researchers who are engaged in advancing with the transduction of four key factors – Oct4, Sox2,
the application of organoid technology in CNS disease Klf4, and cMyc – researchers have been able to generate a
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modeling and neurosurgical innovation. versatile tool that can differentiate into CNS cell lineages,
including neurons, astrocytes, and oligodendrocytes. 23-27
2. Building CNS disease models Unlike hESCs, hiPSCs are derived from a patient’s own
somatic cells, offering the unique advantage of reduced
2.1. Challenges in modeling neural systems immune rejection and the potential for personalized
Accurately modeling human neural system diseases is disease modeling. These cells can simulate fetal brain
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a significant scientific challenge, requiring the precise development and are also applicable for studying adult
recapitulation of multi-scale pathophysiological processes, neurodegenerative and genetic diseases, thus providing a

Volume 1 Issue 1 (2025) 2 doi: 10.36922/or.8261