Objective To establish an "human serum - porcine aortic endothelial cells (PAEC) - human platelets" in vitro model and explore the mechanism of xenotransplantation-related coagulation dysfunction mediated by immune complexes - platelet FcγRⅡa (CD32a) receptor. Methods Healthy human serum was co-incubated with PAEC to prepare the supernatant containing immune complexes, which was then used to stimulate healthy human platelets, or directly treated with the serum of xenogeneic liver transplant recipients. Flow cytometry was used to detect platelet activation markers CD62P and surface IgG binding levels, and the platelet adhesion function was evaluated by platelet-PAEC adhesion experiments. CD32a blocking antibody IV.3 and SYK blocker SKYIN 4 were used to clarify the signaling pathways. Results The supernatant from the co-incubation of healthy human serum and PAEC could significantly induce platelet activation and endothelial adhesion. The use of the serum from xenogeneic liver transplant recipients could also significantly induce platelet activation. Antibody IV.3 and SYK blocker SKYIN 4 could significantly inhibit these effects. Conclusions In xenotransplantation, the immune complexes formed by human serum antibodies and porcine endothelial antigens may induce abnormal platelet activation through the platelet CD32a receptor, which is an important mechanism of non-complement-dependent post-transplant coagulation dysfunction, providing a new target for the intervention of coagulation complications in xenotransplantation.

BACKGROUND:At present,there is a main kind of operation,which is represented by the proximal femoral nail antirotation,to treat femoral intertrochanteric fractures,but some sequelae still occur such as internal fixation loosening,failure,and nail withdrawal.We designed a new femoral neck spiral blade system to solve this problem,so we analyze the mechanical structure by the finite element method that can be regard as the theoretical basis for the system.OBJECTIVE:To compare the mechanical properties of the new femoral neck spiral blade system and the proximal femoral nail antirotation in the treatment of femoral intertrochanteric fracture by the finite element method.METHODS:Based on the finite element model of the femur,the A1.2 and A2.2 femoral intertrochanteric fracture models were established according to the AO fracture classification principle of 2018 edition.The models were fixed with the proximal femoral nail antirotation and the new internal fixation system,applying an axial load of 700,1 400,and 2 100 N above the femoral head.The mechanical characteristics of the two internal fixation methods were respectively compared and analyzed by observing the maximum equivalent stress and the maximum deformation of each group.RESULTS AND CONCLUSION:(1)The maximum equivalent stress of the new internal fixation group under different compressive loads was smaller than that of the proximal femoral nail antirotation group.(2)In the A1.2 fracture model,under different compression loads,the deformation of the new internal fixation system was smaller than that of the proximal femoral nail antirotation group,and the average value of difference between the two was 1.113 mm;the result of the A2.2 type fracture model was the same as that in the A1.1 with an average value of difference of 2.017 mm between the two.(3)In the A1.2 fracture model,under different compressive loads,the maximum deformation of the spiral blade fixed by the new internal fixation system was smaller than that of the proximal femoral nail antirotation group,and the average value of difference between the two was 1.062 mm;the result of the A2.2 type fracture model was the same as that in the A1.1 with an average value of difference of 1.891 mm between the two.(4)The results indicate that the new femoral neck spiral blade system has a lower internal fixation stress value compared to the proximal femoral nail antirotation,and a smaller displacement value of the femur after fixation and internal fixation.It can more effectively fix fractures and prevent the spiral blade from retracting or cutting out in the femoral neck.

BACKGROUND:At present,there is a main kind of operation,which is represented by the proximal femoral nail antirotation,to treat femoral intertrochanteric fractures,but some sequelae still occur such as internal fixation loosening,failure,and nail withdrawal.We designed a new femoral neck spiral blade system to solve this problem,so we analyze the mechanical structure by the finite element method that can be regard as the theoretical basis for the system.OBJECTIVE:To compare the mechanical properties of the new femoral neck spiral blade system and the proximal femoral nail antirotation in the treatment of femoral intertrochanteric fracture by the finite element method.METHODS:Based on the finite element model of the femur,the A1.2 and A2.2 femoral intertrochanteric fracture models were established according to the AO fracture classification principle of 2018 edition.The models were fixed with the proximal femoral nail antirotation and the new internal fixation system,applying an axial load of 700,1 400,and 2 100 N above the femoral head.The mechanical characteristics of the two internal fixation methods were respectively compared and analyzed by observing the maximum equivalent stress and the maximum deformation of each group.RESULTS AND CONCLUSION:(1)The maximum equivalent stress of the new internal fixation group under different compressive loads was smaller than that of the proximal femoral nail antirotation group.(2)In the A1.2 fracture model,under different compression loads,the deformation of the new internal fixation system was smaller than that of the proximal femoral nail antirotation group,and the average value of difference between the two was 1.113 mm;the result of the A2.2 type fracture model was the same as that in the A1.1 with an average value of difference of 2.017 mm between the two.(3)In the A1.2 fracture model,under different compressive loads,the maximum deformation of the spiral blade fixed by the new internal fixation system was smaller than that of the proximal femoral nail antirotation group,and the average value of difference between the two was 1.062 mm;the result of the A2.2 type fracture model was the same as that in the A1.1 with an average value of difference of 1.891 mm between the two.(4)The results indicate that the new femoral neck spiral blade system has a lower internal fixation stress value compared to the proximal femoral nail antirotation,and a smaller displacement value of the femur after fixation and internal fixation.It can more effectively fix fractures and prevent the spiral blade from retracting or cutting out in the femoral neck.