Study on Immune Regulation of Bone Marrow Mesenchymal Stem Cell-Derived Exosomes in Preterm Infants with Brain Injury

In this research, we aimed to investigate the effect of bone marrow mesenchymal stem cells (BMSCs)-derived exosomes on inflammatory factors interleukin-6 and transforming growth factor-beta in the brain injury model of preterm infants, and explore the mechanism of the paracrine effect of BMSCs. The enrichment of BMSCs-derived exosomes was performed by ultracentrifugation. Transmission electron microscopy (TEM) was used to determine the size of exosomes, and protein electrophoresis was used to identify exosome-specific protein molecules. The neonate mice of newborn 3-day-old clean SD rats were randomly divided into four groups: CONTROL group, WMD + PBS group, WMD + SUPERNATANT group and WMD + EXO group. HE staining was used to observe the pathological changes of brain tissue on the 7th day. Immunohistochemical method was used to detect the number of IL-6 and TGF-beta positive cells in the rat brains on the 7th day. The levels of IL-6 and TGF-beta in the brain homogenates were detected by enzyme-linked immunosorbent assay at Day 1, Day 2, Day 3, Day 5 and Day 7, respectively. SPSS 21.0 statistical software was used to statistically analyze the experimental data. This study successfully extracted and identified bone marrow mesenchymal stem cell-derived exosomes. After stereotactic injection of BMSCs-exo into the lateral ventricle, it significantly improved the prognosis of preterm infant brain injury, reduced the amount of pro-inflammatory factors, and promoted protective factors secretion.