Acoustofluidic separation enables early diagnosis of traumatic brain injury based on circulating exosomes

Abstract

Traumatic brain injury (TBI) is a global cause of morbidity and mortality. Initial management and risk stratification of patients with TBI is made difficult by the relative insensitivity of screening radiographic studies as well as by the absence of a widely available, noninvasive diagnostic biomarker. In particular, a blood-based biomarker assay could provide a quick and minimally invasive process to stratify risk and guide early management strategies in patients with mild TBI (mTBI). Analysis of circulating exosomes allows the potential for rapid and specific identification of tissue injury. By applying acoustofluidic exosome separation—which uses a combination of microfluidics and acoustics to separate bioparticles based on differences in size and acoustic properties—we successfully isolated exosomes from plasma samples obtained from mice after TBI. Acoustofluidic isolation eliminated interference from other blood components, making it possible to detect exosomal biomarkers for TBI via flow cytometry. Flow cytometry analysis indicated that exosomal biomarkers for TBI increase in the first 24 h following head trauma, indicating the potential of using circulating exosomes for the rapid diagnosis of TBI. Elevated levels of TBI biomarkers were only detected in the samples separated via acoustofluidics; no changes were observed in the analysis of the raw plasma sample. This finding demonstrated the necessity of sample purification prior to exosomal biomarker analysis. Since acoustofluidic exosome separation can easily be integrated with downstream analysis methods, it shows great potential for improving early diagnosis and treatment decisions associated with TBI.

Neuroprotective and Neurotoxic Effects of Glial-Derived Exosomes

“…Some studies already suggest that finding higher levels of glial-derived exosomes in blood could be used as a disease biomarker in TBI ( Manek et al, 2018 ; Mondello et al, 2020 ; Wang et al, 2021 ), EAE ( Willis et al, 2017 ), and alcohol abuse ( Kodidela et al, 2020 ). Therefore, if new studies arise in the field, connecting number, glial origin and cargo, their assessment would be expected to be useful as a real biomarker for disease.…”

“…Different strategies have been used for identifying the presence of glial-derived exosomes in body fluids, such as plasma and CSF. Some of them have evaluated the presence of GFAP (for astrocyte origin) or isolectin B4 (IB4) (for microglial origin) in total purified exosomes by either western blot of flow cytometry ( Joshi et al, 2014 ; Willis et al, 2017 ; Kodidela et al, 2020 ; Mondello et al, 2020 ; Wang et al, 2021 ). Others have done proteomic analysis, finding GFAP expression as well ( Manek et al, 2018 ), while some have identified glial exosomes by ELISA sandwich, combining glutamate aspartate transporter (GLAST) and CD81 in plasma samples ( Ohmichi et al, 2019 ).…”

Optimization Analysis of Particle Separation Parameters for a Standing Surface Acoustic Wave Acoustofluidic Chip

“…In many biological and medical applications, the efficient separation of particles or cells based on microfluidic approaches provides a convenient, miniaturized, automated, and reliable method for disease diagnosis, − drug screening, , and cell analysis. − The microfluidic technology is also called lab-on-a-chip. Through the design of ingenious microchannel structures and actuators, the entire cell and particle separation process can be scaled down to a small chip.…”

“…In many biological and medical applications, the efficient separation of particles or cells based on microfluidic approaches provides a convenient, miniaturized, automated, and reliable method for disease diagnosis, 1 − 3 drug screening, 4 , 5 and cell analysis. 6 − 8 The microfluidic technology is also called lab-on-a-chip.…”

Optimization of a Translational Murine Model of Closed-head Traumatic Brain Injury

“…and have added to the expanding knowledge of the brain response to mild to moderate TBI by increasing the understanding of mechanisms, pathological outcomes, and therapeutic interventions after injury [16][17][18][19][20][21][22] . Adapting closedhead TBI models for mice allows researchers to increase throughput and leverage transgenic approaches for mechanistic studies.…”