Growth Factor Signaling in Solid Organ Transplantation: A Conceptual Framework for Chronic Remodeling and Survival

Long-term survival after solid organ transplantation remains limited by chronic remodeling, fibrosis, vascular complications, and malignancy despite advances in immunosuppressive therapy. Current monitoring strategies primarily rely on functional and immunological parameters that often identify complications only after irreversible injury has occurred. There is a critical need for earlier, mechanistically informative biomarkers that can predict survival outcomes. Many platelet-associated growth factors (PDGF, TGF-β, VEGF, EGF, and IGF-1) are stored in platelet α-granules but can also originate from immune, endothelial, and stromal cells, regulate angiogenesis, extracellular matrix deposition, immune modulation, and tissue repair-processes central to graft adaptation and chronic injury. In this review, we propose the growth factor signaling network as a conceptual framework that potentially links platelet biology, ischemia-reperfusion injury, alloimmune responses, and chronic immunosuppression to sustained growth factor signaling and maladaptive graft remodeling. This framework should be interpreted as a biologically plausible integrative model rather than a fully validated mechanistic pathway in transplant recipients. Importantly, direct clinical evidence linking platelet activation markers (e.g., P-selectin, PF4, β-thromboglobulin) with circulating growth factor levels and long-term transplant outcomes remains limited, highlighting a critical gap in current biomarker research. Emerging clinical evidence suggests their potential prognostic relevance in transplant outcomes. Elevated TGF-β levels have been associated with increased risk of opportunistic infections, while early postoperative IGF-1 concentrations predict short-term survival. Increased VEGF-A levels correlate with primary graft dysfunction and cardiac allograft vasculopathy, while PDGF isoforms contribute to fibrotic and vascular progression across transplanted organs. However, their clinical applicability is limited by methodological variability and lack of large-scale validation. Rather than serving solely as markers of rejection, platelet-associated growth factors may reflect dynamic processes involved in transplant remodeling and mortality risk. Incorporating growth factor profiling into multiparametric survival prediction models may improve early risk stratification and support precision post-transplant management strategies.