Platelet‐rich plasma exhibits antibacterial and anti‐inflammatory effects in an in vitro donkey endometritis model

Background Infectious endometritis, mainly caused by Escherichia coli ( E. coli ) and Streptococcus equi subsp. zooepidemicus ( SEZ ), significantly impairs donkey reproductive performance. Platelet‐rich plasma (PRP) shows promise as an anti‐inflammatory and antibiotic alternative. Objectives To evaluate PRP's antimicrobial efficacy against key pathogens and assess its anti‐inflammatory and tissue repair properties in an in vitro endometrial model. Study Design Non‐randomised in vitro and explant experiments. Methods In in vitro antibacterial assays, the inhibitory effects of PRP on the growth of E. coli and SEZ were evaluated. In an in vitro infected endometrial explant model, tissues were treated with PRP, ceftiofur (CEF), 1/2 MIC CEF, or PRP combined with 1/2 MIC CEF. Antibacterial efficacy was evaluated by bacterial load quantification, while inflammatory and healing responses were assessed by measuring the protein levels of pro‐inflammatory cytokines (IL‐1β, IL‐6, TNF‐α), anti‐inflammatory cytokine (IL‐10), tissue repair factor (TGF‐β), matrix metallopeptidase 9 (MMP‐9), and histological examination of the endometrium. Results 50% PRP significantly inhibited E. coli and SEZ during an 8 h culture period ( p < 0.05), although efficacy decreased by 24 h. In the SEZ model, PRP reduced bacterial load, IL‐1β, IL‐6, TNF‐α, and TGF‐β levels while enhancing the expression of IL‐10 and MMP‐9 ( p < 0.05). In the E. coli model, PRP + 1/2 MIC CEF demonstrated synergistic antibacterial and optimal anti‐inflammatory effects ( p < 0.05). PRP also promoted epithelial and glandular repair as indicated by upregulated MMP‐9 levels. Main Limitations Models may not fully replicate complex co‐infections and cell interactions. Conclusion The antibacterial efficacy of PRP depends on concentration, duration, and pathogen type, with PRP showing greater inhibitory effects against SEZ than E. coli . Application strategies should be tailored to the type of infectious endometritis to maximise the effect of PRP.