Understanding Primary Blast Injury: High Frequency Pressure Acutely Disrupts Neuronal Network Dynamics in Cerebral Organoids

Abstract

Blast exposure represents a common occupational risk capable of generating mild to severe traumatic brain injuries (TBI). During blast exposure, a pressure shockwave passes through the skull and exposes brain tissue to complex pressure waveforms. The primary neurophysiological response to blast-induced pressure waveforms remains poorly understood. Here, we use a computer-controlled table-top pressure chamber to expose human stem cell–derived cerebral organoids to varied frequency of pressure waves and characterize the neurophysiological response. Pressure waves that reach a maximum amplitude of 250 kPa were used to model a less severe TBI and 350 kPa for a more severe blast TBI event. With each amplitude, a frequency range of 500 Hz, 3000 Hz, and 5000 Hz was tested. Following the 250 kPa overpressure a multi-electrode array recorded organoid neural activity. We observed an acute suppression neuronal activity in single unit events, population events, and network oscillations that recovered within 24 h. Additionally, we observed a network desynchronization after exposure higher frequency waveforms. Conversely, organoids exposed to higher amplitude pressure (350k Pa) displayed drastic neurophysiological differences that failed to recover within 24 h. Further, lower amplitude “blast” (250 kPa) did not induce cellular damage whereas the higher amplitude “blast” (350 kPa) generated greater apoptosis throughout each organoid. Our data indicate that specific features of pressure waves found intracranially during blast TBI have varied effects on neurophysiological activity that can occur even without cellular damage.

Opening the black box of traumatic brain injury: a holistic approach combining human 3D neural tissue and an in vitro traumatic brain injury induction device

“…Although there was some variability observed among the various injured tissues, a distinct reduction in spontaneous activity recorded from most electrodes on the MEAs was noted. These observations are in accordance with previous studies carried out in vivo (Ding et al, 2011 ; Johnstone et al, 2013 ) and in vitro (Silvosa et al, 2022 ). Gradual restoration of spontaneous activity was also observed over time.…”

“…This is a significant weakness as traumatic brain injuries typically involve structural damage to the brain and affect different types of cells and networks of cellular interaction. To overcome this limitation, bioengineered tissues grown in 3D culture systems, mimicking native brain anatomy and physiological responses, are emerging as powerful in vitro models to investigate the pathophysiology of TBI (Ramirez et al, 2021b ; Silvosa et al, 2022 ). This led to the development of a new in vitro model of TBI combining human cells organized in a 3D neural tissue subjecting to fluid percussion injury.…”

“…Recent technological advancements have allowed the creation of 3D brainlike structures called cerebral organoids (Chiaradia and Lancaster, 2020 ), which resemble the cellular and anatomical composition of different regions of the human brain and can mimic disease pathways (Lancaster et al, 2013 ; Mariani et al, 2015 ; Garcez et al, 2016 ; Pollen et al, 2019 ; Velasco et al, 2019 ). Human brain organoids are becoming an emerging tool in TBI and mTBI as they provide a window into the injured tissues after trauma (Jgamadze et al, 2020 ; Ramirez et al, 2021a , b ) and over time into the chronic phase of injury (Silvosa et al, 2022 ).…”