Quantitative Characteristics of Small Extracellular Vesicles from the Blood of Patients with Non-Suicidal Self-Injury

Abstract—The aim of the study was to determine the quantitative characteristics of small extracellular vesicles (sEV) in the blood of patients with non-suicidal self-injury (NSSI) and comparison of the concentration and size of sEVs in patients with major depressive disorder (MDD) with and without NSSI, as well as to assess the relationship between the size and concentration of sEVs in the sample with such parameters as the severity of situational and personal anxiety, depression, and suicidal risk. The study included 28 patients (11 m/17 f) with a current episode of major depression and at least five episodes of NSSI in the last 12 months (main group, mean age 28.3 years) and 28 patients with major depression identical in sex and age without NSSI throughout life (comparison group). Patients’ mental status was assessed using the MINI interview, the Beck Depression Inventory II (BDI II), and the Spielberger Anxiety Scale. Isolation of sEVs from blood was carried out using polyethylene glycol (PEG) precipitation and gel filtration. The size and concentration of isolated particles were estimated using dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). The groups differed significantly in the severity of depression according to the BDI-II questionnaire, the Spielberger Situational Anxiety Scale, and the Spielberger Personality Anxiety Scale. The assessment of suicidal risk, carried out according to the corresponding module of the MINI questionnaire, revealed a significantly larger number of participants with medium and high suicidal risk in the group of patients with NSSI. The sEV fraction was isolated from the blood of the patients of the main group and the comparison group. There were no differences in the concentration or size of sEVs between groups of patients with depression with and without NSSI. In our study, we found no dependence of the concentration and size of sEVs on the severity of depression, situational and personal anxiety, and the severity of suicidal risk. Conclusion: NSSI in individuals with major depressive disorder is associated with a more severe course of the disorder (greater severity of depression, situational and personal anxiety), as well as a higher risk of suicide. Our study did not reveal any differences in the quantitative characteristics of sEV in patients with a depressive episode with and without NSSI. Future studies should focus on investigating the structural differences and functional features of sEVs in NSSI.