Combined Phloretin and Human Platelet-rich Plasma Effectively Preserved Integrities of Brain Structure and Neurological Function in Rat after Traumatic Brain Damage

Abstract

This study investigates whether phloretin, a brain-edema inhibitor, can enhance the therapeutic effects of human-derived platelet-rich plasma (hPRP) in reducing brain hemorrhagic volume (BHV) and preserving neurological function in rodents following acute traumatic brain damage (TBD) Forty rats were divided into five groups: sham-control, TBD, TBD + phloretin (80 mg/kg/dose intraperitoneally at 30 minutes and on days 2/3 post-TBD), TBD + hPRP (80μL by left intra-carotid-artery injection at 3 hours post-TBD), and TBD + phloretin + hPRP. Cerebral tissues were harvested on day 28 post-TBD for analysis. Brain MRI on day 28 showed the lowest BHV in the sham-control group and the highest in the TBD group. BHV was significantly lower in the phloretin + hPRP group compared to the phloretin or hPRP alone groups, which had similar BHV. Neurological function followed an inverse pattern to BHV. By day 28, protein levels of upstream (HGMB1, TLR-2, TLR-4, MyD88, Mal, TRAM, TRIF, TRAF6, IKK-α, IKK-ß, p-NF-κB) and downstream (IL-1ß, TNF-α, iNOS) inflammation signalings, apoptosis (caspase3, PARP), and fibrosis (Smad3, TGF-ß) biomarkers, as well as flow cytometric assessment of inflammatory cells (CD11b/c+, Ly6G+, PMO+) and early (AN-V+/PI-) and late (AN-V+/PI+) mononuclear-cell apoptosis, displayed patterns similar to BHV. The number of inflammatory (CD68+, MMP9+) and brain-swelling/myelin-damaged (AQP4+, GFAP+) mediators also followed this pattern, while neuronal-myelin (Doublecortin+, NeuN, nestin) mediators showed an inverse relationship with BHV (all p<0.0001). Combined phloretin and hPRP therapy is superior to either treatment alone in protecting the brain against TBD, primarily by suppressing inflammatory signaling and brain-swelling biomarkers.