Human Astrocyte Matrisome Enhances Neural Network Formation for Use in Transplant Therapy in Cortical Vision Loss

Damage to the occipital cortex disrupts established neural tracks and networks resulting in poor vision processing and blindness. Regeneration of these networks are inherently slow; thus, expediting recovery of synapses in this region is imperative. Here, we demonstrate the use of synapse-promoting mechanisms of astrocytes in human organoid systems to develop rapid and mature neural networks within 28 days.

314 Human Astrocyte Matrisome Enhances Neural Network Formation for Use in Transplant Therapy in Cortical Vision Loss Megh Patel 1, Sailee Lavekar 2, Sajedeh Nasr Esfahani 2, Samira Aghlara-Fotovat 3, Suki Oji 2, Omid Veiseh 3, Robert Krencik 2 1 Texas A&M School of Medicine, 2 Houston Methodist Research Institute, 3 Rice University Introduction: Damage to the occipital cortex disrupts established neural tracks and networks resulting in poor vision processing and blindness. Regeneration of these networks are inherently slow; thus, expediting recovery of synapses in this region is imperative. Here, we demonstrate the use of synapse-promoting mechanisms of astrocytes in human organoid systems to develop rapid and mature neural networks within 28 days. Methods: Transgenic stems cells engineered for rapid maturation into neurons and astrocytes were differentiated in 3 and 12 days respectively and were combined in 3-dimensional organoid coculture (Asteroids) versus monocultures of neurons-only (Neurospheres). Results: Asteroids showed increased synchronicity and frequency of neural burst activity seen both in multi-electrode array (MEA) analysis and Ca2+-imaging when compared to neurospheres. To further specify the mechanism, transcriptome analysis of stem-cell derived astrocytes compared to neural progenitor cells identified known synaptogenic matricellular protein Thrombospondin-1 (THBS1) and multiple matrix chondroitin sulfate (CS) proteoglycans to be uniquely secreted by astrocytes. Immunohistochemistry imaging of asteroids confirmed that astrocytes secrete significantly more proteoglycans than neurospheres. To test these components upon neural networks, exogenous addition of THBS1 to neurospheres showed increased frequency of synaptic bursts on Ca2+-imaging and increased spike frequency on MEA. This effect was blocked with cotreatment of gabapentin, an anticonvulsant known to antagonize THBS1 at its receptor, α2∂1. Chondroitin sulfate treatment of neurospheres also increased Ca2+ bursts. Thus, astrocyte-mediated synaptogenesis offers therapeutic potential to restore neural networks in injured and diseased areas; therefore, we genetically engineered human asteroids to overexpress THBS1 via lentivirus transduction. Encapsulation of these asteroids in alginate hydrogel capsules provide a nonimmunogenic and non-motile environment permitting transplantation of capsules to an injured occipital cortex in vivo. Conclusions: Overall, we identified and characterized the role of astrocytes in generating robust neural networks and propose a therapy to regenerate networks after occipital neurotrauma or stroke to expeditiously restore visual function. References: None provided. Keywords: Trauma, Stroke, Higher visual functions, Miscellaneous Financial Disclosures: The authors had no disclosures. Grant Support: Mission Connect, a program of TIRR Foundation (#022-105) National Institute of Neurological Disorders and Stroke (R01NS129788). Contact Information: Megh Dipak Patel, [e-mail] 470 | North American Neuro-Ophthalmology Society