Three-Dimensional Organoid System Transplantation Technologies in Future Treatment of Central Nervous System Diseases

The Application of Brain Organoid Technology in Stroke Research: Challenges and Prospects

Stroke is a neurological disease responsible for significant morbidity and disability worldwide. However, there remains a dearth of effective therapies. The failure of many therapies for stroke in clinical trials has promoted the development of human cell-based models, such as brain organoids. Brain organoids differ from pluripotent stem cells in that they recapitulate various key features of the human central nervous system (CNS) in three-dimensional (3D) space. Recent studies have demonstrated that brain organoids could serve as a new platform to study various neurological diseases. However, there are several limitations, such as the scarcity of glia and vasculature in organoids, which are important for studying stroke. Herein, we have summarized the application of brain organoid technology in stroke research, such as for modeling and transplantation purposes. We also discuss methods to overcome the limitations of brain organoid technology, as well as future prospects for its application in stroke research. Although there are many difficulties and challenges associated with brain organoid technology, it is clear that this approach will play a critical role in the future exploration of stroke treatment.

Vitrification for cryopreservation of 2D and 3D stem cells culture using high concentration of cryoprotective agents

BACKGROUND

Vitrification is the most promising technology for successful cryopreservation of living organisms without ice crystal formation. However, high concentrations (up to ~ 6-8 M) of cryoprotective agents (CPAs) used in stem cell induce osmotic and metabolic injuries. Moreover, the application of conventional slow-freezing methods to cultures of 3-D organoids of stem cells in various studies, is limited by their size.

RESULTS

In this study, we evaluated the effect of high concentrations of CPAs including cytotoxicity and characterized human mesenchymal stem cell (MSC) at single cell level. The cell viability, cellular damage, and apoptotic mechanisms as well as the proliferation capacity and multipotency of cells subjected to vitrification were similar to those in the slow-freezing group. Furthermore, we identified the possibility of vitrification of size-controlled 3-D spheroids for cryopreservation of organoid with high survivability.

CONCLUSIONS

Our results demonstrate successful vitrification of both single cell and spheroid using high concentration of CPAs in vitro without cytotoxicity.

Brain Organoids: Tiny Mirrors of Human Neurodevelopment and Neurological Disorders

Unravelling the complexity of the human brain is a challenging task. Nowadays, modern neurobiologists have developed 3D model systems called "brain organoids" to overcome the technical challenges in understanding human brain development and the limitations of animal models to study neurological diseases. Certainly like most model systems in neuroscience, brain organoids too have limitations, as these minuscule brains lack the complex neuronal circuitry required to begin the operational tasks of human brain. However, researchers are hopeful that future endeavors with these 3D brain tissues could provide mechanistic insights into the generation of circuit complexity as well as reproducible creation of different regions of the human brain. Herein, we have presented the contemporary state of brain organoids with special emphasis on their mode of generation and their utility in modelling neurological disorders, drug discovery, and clinical trials.

Organoid technology in female reproductive biomedicine

Recent developments in organoid technology are revolutionizing our knowledge about the biology, physiology, and function of various organs. Female reproductive biology and medicine also benefit from this technology. Organoids recapitulate features of different reproductive organs including the uterus, fallopian tubes, and ovaries, as well as trophoblasts. The genetic stability of organoids and long-lasting commitment to their tissue of origin during long-term culture makes them attractive substitutes for animal and in vitro models. Despite current limitations, organoids offer a promising platform to address fundamental questions regarding the reproductive system's physiology and pathology. They provide a human source to harness stem cells for regenerative medicine, heal damaged epithelia in specific diseases, and study biological processes in healthy and pathological conditions. The combination of male and female reproductive organoids with other technologies, such as microfluidics technology, would enable scientists to create a multi-organoid-on-a-chip platform for the next step to human-on-a-chip platforms for clinical applications, drug discovery, and toxicology studies. The present review discusses recent advances in producing organoid models of reproductive organs and highlights their applications, as well as technical challenges and future directions.

Vascularization and Engraftment of Transplanted Human Cerebral Organoids in Mouse Cortex

Neural stem cells (NSCs) hold great promise for neural repair in cases of CNS injury and neurodegeneration; however, conventional cell-based transplant methods face the challenges of poor survival and inadequate neuronal differentiation. Here, we report an alternative, tissue-based transplantation strategy whereby cerebral organoids derived from human pluripotent stem cells (PSCs) were grafted into lesioned mouse cortex. Cerebral organoid transplants exhibited enhanced survival and robust vascularization from host brain as compared to transplants of dissociated neural progenitor cells (NPCs). Engrafted cerebral organoids harbored a large NSC pool and displayed multilineage neurodifferentiation at two and four weeks after grafting. Cerebral organoids therefore represent a promising alternative source to NSCs or fetal tissues for transplantation, as they contain a large set of neuroprogenitors and differentiated neurons in a structured organization. Engrafted cerebral organoids may also offer a unique experimental paradigm for modeling human neurodevelopment and CNS diseases in the context of vascularized cortical tissue.