Exosomes: New biomarker and therapeutic candidates in autism spectrum disorder research

Background: There is no recognised cure or specific biomarker for autism spectrum disorder (ASD). Exosomes are small vesicles that carry proteins, lipids and nucleic acids. They have been investigated for diseases such as Parkinson's and Alzheimer's. As the conclusions were on the biological utility of exosomes as a non-invasive brain biopsy, some animal, human and in vitro exosome studies have also been presented in the ASD field. The purpose of this review is to compile the studies that have established a relationship between ASD and exosomes so far and discuss their potential for linking the gap between the laboratory and clinic.Methods: In this systematic review, 31 PubMed articles were identified using the keywords 'exosomal', 'exosome and 'autism spectrum disorder'. After excluding 16 reviews, 4 irrelevant studies and 1 preprint, and adding 5 relevant articles, 15 research articles were included based on PRISMA criteria. The articles were investigated and reviewed by both authors. Their methodology and results are also discussed according to two main streams in studies.Results: Numerous studies have identified potential biomarkers, including mitochondrial DNA (mtDNA7S), cytokines including IL-1 beta, TNF-alpha and IL-6, and different types of RNAs by comparing the exosomal contents of ASD patients or models with controls. In studies that focused on treatment, behavioural improvements were shown in ASD model mice.Conclusion: Since there are presently no reliable biomarkers or effective treatments for ASD, exosome-based research offers a promising avenue for early diagnosis and the creation of tailored therapies.