Serum Syndecan-1: a potent prognostic biomarker for transplant outcomes.

Introduction: Post-transplant-associated complications arising from endothelial injury, such as sinusoidal obstruction syndrome (SOS) and transplant-associated thrombotic microangiopathy (TA-TMA), are associated with high mortality rates following hematopoietic stem cell transplantation (HSCT). Syndecan-1 (SDC1), a cell-surface proteoglycan released into the circulation upon endothelial damage, is a potential biomarker for vascular integrity. We previously demonstrated that elevated serum SDC1 levels were associated with disease severity and poor prognosis in patients with COVID-19. Methods: This prospective study investigated whether longitudinal serum SDC1 kinetics could predict early mortality in HSCT recipients; serial blood samples were collected from 130 patients undergoing hematopoietic stem cell transplantation (HSCT), from the day of HSCT through day 28 post-transplant, to investigate whether serum SDC1 levels could serve as a predictive marker for early mortality within 100 days after HSCT. Results: During the observation period, 12 patients died, of whom 9 deaths were attributed to conditions associated with endothelial injury, including SOS ( Conclusion: These findings suggest that serum SDC1 has the potential to predict early post-transplant mortality and warrants further validation in larger prospective studies.