422.2: Investigating Galectin-3 as a Novel Therapeutic Target To Block Inflammation and Reduce Ischemia Reperfusion Injury During Vascular Composite Allograft Transplantation

Abstract

Introduction: Vascularized Composite Allograft (VCA) transplantation is a treatment option for complex injuries that leave patients with structural and functional deficits that cannot be adequately reconstructed. During transplantation, grafts are subjected to hypoxic/ischemic injury during procurement, storage, and reperfusion. Skin and muscle containing VCA are highly susceptible to ischemia reperfusion injury. Galectin-3 is an endogenous β-galactoside binding lectin known to play a role in driving inflammatory responses in response to hypoxic/ischemic stress. Blocking galectin-3 using known inhibitors including modified citrus pectin (MCP) has been shown in animal models to reduce inflammation and fibrosis. We hypothesized that galectin-3 significantly contributes to VCA IRI and that blocking galectin-3 can serve as a novel therapeutic approach to prevent or reduce IRI. We aimed to determine the role of galectin-3 in VCA ischemia reperfusion injury and the effect of blocking galectin-3 using MCP in syngeneic VCA models. Method: Male Brown Norway rats underwent syngeneic hind limb transplantation following 0, 6 or 24 hours of cold ischemia time. A group of rats receiving hind limbs subjected to 24 hours of static cold storage were treated with MCP (1% w/v) in the drinking water starting one week prior to transplantation. Recipient serum and donor VCA tissues were collected at end-of-study 6 days post transplantation. Sera and tissues collected from naive Brown Norway rats were included as controls. Sera levels of galectin-3 were determined by sandwich ELISA (Novus Biologics, Inc). Galectin-3 expression in the muscle was determined by Western Blotting. The degree of inflammation in the muscle tissue was determined by H&E. Results: Sera galectin-3 levels averaged 0.854±0.557ng/ml in naïve BN rats (n=7), 4.232±2.134ng/ml in recipients of grafts transplanted immediately without static cold storage (n=3), 12.86±1.292ng/ml in recipients of grafts subjected to 6 hours cold storage without MCP treatment (n=3),20.10±3.185ng/ml in recipients of grafts subjected to 24 hours cold storage without MCP treatment (n=6), and 12.77±2.098ng/ml in recipients of grafts subjected to 24 hours cold storage with MCP treatment (n=9) (Figure 1A). Galectin-3 expression in the VCA muscle increased according to the extent of cold ischemia. MCP treatment decreased muscle galectin-3 expression (Figure 1B) and inflammation in the muscle (Figure 2) post transplantation.Conclusion: Galectin-3 levels significantly increased in recipient sera and donor muscle within a week in rats transplanted with donor VCA grafts subjected to prolonged ischemia. Blocking galectin-3 using MCP can reduce the amount of galectin-3 in circulation and muscle tissue post transplantation and may decrease inflammation associated with VCA IRI. Galectin-3 may serve as a novel therapeutic target to reduce inflammation associated with ischemic injury and improve VCA outcomes. DOD CDMRP RTRP W81XWH1910163 RT180168.