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1. TERMIS AM

   Teal Russell, Qassim Dirar (July 2023, Development of Cortical Spheroid Tissue Constructs with Perfusable Microvasculature Platform)

   Human induced pluripotent stem cell (hiPSC)-derived brain spheroids can recapitulate the complex cytoarchitecture of the brain as well as the genetic/epigenetic footprint of human brain development. Although the brain spheroids can mimic the structures and functions of the brain in vivo at certain complexity, the 3D models do not have a perfusable microvascular network that can provide the interaction with spheroids. Here we report on a microfluidic-based three-dimensional, cortical spheroid tissue grafted on the vascular-network. Angiogenic sprouting was induced by using concentration gradient-driven angiogenic factors and its vascularized network was characterized in terms of morphology, directional alignment under perfusion, lumen formation, and permeability. This paper demonstrates the potential utility of a membrane-free in vitro cortical spheroid tissue construct with perfusable microvascular network that can be scaled up to a high throughput platform as a cost-effective alternative platform to model brain diseases and disorders. 

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2. Multimodal monitoring of human cortical organoids implanted in mice reveal functional connection with visual cortex

   https://doi.org/10.1038/s41467-022-35536-3  

   Wilson, Madison N.; Thunemann, Martin; Liu, Xin; Lu, Yichen; Puppo, Francesca; Adams, Jason W.; Kim, Jeong-Hoon; Ramezani, Mehrdad; Pizzo, Donald P.; Djurovic, Srdjan; et al (December 2022, Nature Communications)

   Abstract Human cortical organoids, three-dimensional neuronal cultures, are emerging as powerful tools to study brain development and dysfunction. However, whether organoids can functionally connect to a sensory network in vivo has yet to be demonstrated. Here, we combine transparent microelectrode arrays and two-photon imaging for longitudinal, multimodal monitoring of human cortical organoids transplanted into the retrosplenial cortex of adult mice. Two-photon imaging shows vascularization of the transplanted organoid. Visual stimuli evoke electrophysiological responses in the organoid, matching the responses from the surrounding cortex. Increases in multi-unit activity (MUA) and gamma power and phase locking of stimulus-evoked MUA with slow oscillations indicate functional integration between the organoid and the host brain. Immunostaining confirms the presence of human-mouse synapses. Implantation of transparent microelectrodes with organoids serves as a versatile in vivo platform for comprehensive evaluation of the development, maturation, and functional integration of human neuronal networks within the mouse brain. 

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3. Multicellular 3D Neurovascular Unit Model for Assessing Hypoxia and Neuroinflammation Induced Blood-Brain Barrier Dysfunction

   https://doi.org/10.1038/s41598-020-66487-8  

   Nzou, G; Wicks, R. T.; N. R., Mekky; G. A., Seale; S. A., Aya; ... & Atala, A. J (June 2020, Scientific reports)

   The blood-brain barrier (BBB) is a dynamic component of the brain-vascular interface that maintains brain homeostasis and regulates solute permeability into brain tissue. The expression of tight junction proteins between adjacent endothelial cells and the presence of efflux proteins prevents entry of foreign substances into the brain parenchyma. BBB dysfunction, however, is evident in many neurological disorders including ischemic stroke, trauma, and chronic neurodegenerative diseases. Currently, major contributors to BBB dysfunction are not well understood. Here, we employed a multicellular 3D neurovascular unit organoid containing human brain microvascular endothelial cells, pericytes, astrocytes, microglia, oligodendrocytes and neurons to model the effects of hypoxia and neuroinflammation on BBB function. Organoids were cultured in hypoxic chamber with 0.1% O2 for 24 hours. Organoids cultured under this hypoxic condition showed increased permeability, pro-inflammatory cytokine production, and increased oxidative stress. The anti-inflammatory agents, secoisolariciresinol diglucoside and 2-arachidonoyl glycerol, demonstrated protection by reducing inflammatory cytokine levels in the organoids under hypoxic conditions. Through the assessment of a free radical scavenger and an anti-inflammatory endocannabinoid, we hereby report the utility of the model in drug development for drug candidates that may reduce the effects of ROS and inflammation under disease conditions. This 3D organoid model recapitulates characteristics of BBB dysfunction under hypoxic physiological conditions and when exposed to exogenous neuroinflammatory mediators and hence may have potential in disease modeling and therapeutic development. 

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4. The Use of Pluripotent Stem Cell-Derived Organoids to Study Extracellular Matrix Development during Neural Degeneration

   https://doi.org/10.3390/cells8030242  

   Yan, Yuanwei; Bejoy, Julie; Marzano, Mark; Li, Yan (March 2019, Cells)

   The mechanism that causes the Alzheimer’s disease (AD) pathologies, including amyloid plaque, neurofibrillary tangles, and neuron death, is not well understood due to the lack of robust study models for human brain. Three-dimensional organoid systems based on human pluripotent stem cells (hPSCs) have shown a promising potential to model neurodegenerative diseases, including AD. These systems, in combination with engineering tools, allow in vitro generation of brain-like tissues that recapitulate complex cell-cell and cell-extracellular matrix (ECM) interactions. Brain ECMs play important roles in neural differentiation, proliferation, neuronal network, and AD progression. In this contribution related to brain ECMs, recent advances in modeling AD pathology and progression based on hPSC-derived neural cells, tissues, and brain organoids were reviewed and summarized. In addition, the roles of ECMs in neural differentiation of hPSCs and the influences of heparan sulfate proteoglycans, chondroitin sulfate proteoglycans, and hyaluronic acid on the progression of neurodegeneration were discussed. The advantages that use stem cell-based organoids to study neural degeneration and to investigate the effects of ECM development on the disease progression were highlighted. The contents of this article are significant for understanding cell-matrix interactions in stem cell microenvironment for treating neural degeneration. 

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5. The pericyte microenvironment during vascular development

   https://doi.org/10.1111/micc.12554  

   Payne, Laura B.; Zhao, Huaning; James, Carissa C.; Darden, Jordan; McGuire, David; Taylor, Sarah; Smyth, James W.; Chappell, John C. (May 2019, Microcirculation)

   Abstract Vascular pericytes provide critical contributions to the formation and integrity of the blood vessel wall within the microcirculation. Pericytes maintain vascular stability and homeostasis by promoting endothelial cell junctions and depositing extracellular matrix (ECM) components within the vascular basement membrane, among other vital functions. As their importance in sustaining microvessel health within various tissues and organs continues to emerge, so does their role in a number of pathological conditions including cancer, diabetic retinopathy, and neurological disorders. Here, we review vascular pericyte contributions to the development and remodeling of the microcirculation, with a focus on the local microenvironment during these processes. We discuss observations of their earliest involvement in vascular development and essential cues for their recruitment to the remodeling endothelium. Pericyte involvement in the angiogenic sprouting context is also considered with specific attention to crosstalk with endothelial cells such as through signaling regulation and ECM deposition. We also address specific aspects of the collective cell migration and dynamic interactions between pericytes and endothelial cells during angiogenic sprouting. Lastly, we discuss pericyte contributions to mechanisms underlying the transition from active vessel remodeling to the maturation and quiescence phase of vascular development. 

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