VP5: Plasma Derived Extracellular Vesicles as a Treatment Option in Nerve Regeneration- An In-Vitro Study

Abstract

INTRODUCTION: Previous experiments with Extracellular Vesicles (EVs) derived from highly proliferative mesenchymal stromal cells, f.e. adipose tissue derived stromal cells (ADSC), showed in-vitro an increased proliferation, and migration of Schwann cells and in-vivo an improvement of nerve regeneration in nerve lesion models. However, the isolation process of EVs from cell cultures is laborious with a plenty of processing steps and a low recovery rate. In addition, the harvest requires an invasive procedure, f.e. liposuction, or bone marrow puncture. As an alternative, EVs isolated from blood plasma showed proliferative effects on osteoblasts, chondrocytes, and fibroblast. The goal of this experiments was to investigate the effects of EVs isolated from blood plasma on proliferation of Schwann cells. MATERIALS AND METHODS: EVs were isolated from rat plasma, and conditioned medium from rat ADSC culture with differential ultracentrifugation steps. The amount and size of EVs was determined by Nanoparticle Tracking Analysis (NTA) with a Zetaview Particlemetrix®. ADSC-EVs in one dosage and Plasma-EVs in two dosages were added to primary rat Schwann cells culture. As control, Schwann cells were incubated in common growth medium. The proliferation rate was determined by EdU-proliferation assay. RESULTS: NTA results showed, that EVs derived from plasma were slightly larger than ADSC-EVs. Further, Plasma-EVs significantly outnumbered ADSC-EVs per volume. Schwann cells treated with ADSC-EVs showed highest proliferation rate. Plasma-EVs in highest dosage were superior to control, whereas plasma-EVs in lower dosage missed to show a proliferative effect in comparison to control group. CONCLUSION: Our results showed a proliferative effect of Plasma-EVs on Schwann cells. Moreover, we could show an easy isolation of EVs in a large amount. Thus, plasma-EVs could be an autologous treatment option with an absent donor site morbidity for critical nerve defects. However, further investigation of Plasma-EVs in proliferation and migration assays, and of the specific cargo are needed.