Establishment of a Novel in vitro Model of Sepsis-Induced Myocardial Injury Using Septic Serum: A Comprehensive Comparative Study

Background: Sepsis is a life-threatening systemic inflammatory syndrome, in which myocardial injury plays a key role in disease progression and poor outcomes. However, the precise mechanisms underlying sepsis-induced myocardial injury remain unclear, and the most appropriate in vitro model for its investigation remains to be established. This study aimed to systematically compare different in vitro models to determine the most appropriate model for studying the pathophysiological mechanisms of sepsis-induced myocardial injury. Materials and Methods: AC16 cardiomyocytes were treated with lipopolysaccharide (LPS), tumor necrosis factor-α (TNF-α), or septic serum for 24 hours to induce myocardial injury. Cell viability, cytotoxicity, inflammatory response, oxidative stress, apoptosis, and myocardial injury biomarkers were assessed to evaluate model performance. The mRNA expression profiles were analyzed to identify differentially expressed genes (DEGs), followed by functional enrichment analysis. The diagnostic utility of each model was assessed using receiver operating characteristic (ROC) analysis. Results: While LPS and TNF-α-treated cardiomyocytes exhibited similar injury features, both only partially captured the complexity of the sepsis-induced myocardial injury phenotype. In contrast, cardiomyocytes exposed to septic serum demonstrated more pronounced inflammatory responses, oxidative stress, apoptosis, and myocardial damage. Transcriptomic analysis revealed that the septic serum model induced 706 DEGs, significantly more than LPS (262 DEGs) or TNF-α (237 DEGs), and enriched in a broader array of biological processes and signaling pathways. ROC analysis confirmed that the septic serum model (AUC=0.671, 0.610) had higher diagnostic accuracy for septic cardiomyopathy datasets compared to the LPS (AUC= 0.548, 0.426) and TNF-α (AUC= 0.470, 0.559) models. Conclusion: This study introduces a novel in vitro approach using septic serum to model sepsis-induced myocardial injury, providing a physiologically relevant platform that more accurately reflects the complex pathophysiology of the disease.