Disparity, Liver Demand, and Access to Transplants

Immune response against the biomaterials used in 3D bioprinting of organs

Regenerative medicine has developed promising approaches for healing and replacing defective and damaged organs or tissues with functional ones. Three-dimensional (3D) bioprinting innovation has integrated a potential to design organs or tissues specific to the patient with the capability of rapid construction to fulfill the storage of organs and the need for transplantation. 3D bioprinting of organs has the main goal to develop a structural and functional organ or tissue mimic to the original one. The highly complex fabrication of tissue engineering scaffolds containing biomaterials, tissue models, and biomedical devices has made it possible to print small blood vessels to mimic organs to reduce organ or tissue rejection. 3D bioprinting has the concept of bioinks containing biomaterials that may trigger the immune responses in the body. Nevertheless, foreign body response (FBR) is mediated by various cell types such as B-cells, dendritic cells, macrophages, natural killer cells, neutrophils, and T-cells, and molecular signals such as antibodies (Abs), cytokines, and reactive radical species. Typically, the biomaterial is shielded by the fibrous encapsulation that is regulated by molecular signals. This review explored the progress in 3D bioprinting of vital organs and basic immune response against the biomaterials used in this approach. Thus, evaluating immune response against biomaterials used in 3D printed organs is necessary to mitigate tissue rejection after the transplantation.

Between-center disparities in access to heart transplantation in France: contribution of candidate and center factors - A comprehensive cohort study

Transplantation represents the last option for patients with advanced heart failure. We assessed between-center disparities in access to heart transplantation in France 1 year after registration and evaluated the contribution of factors to these disparities. Adults (n = 2347) registered on the French national waiting list between January 1, 2010, and December 31, 2014, in the 23 transplant centers were included. Associations between candidate and transplant center characteristics and access to transplantation were assessed by proportional hazards frailty models. Candidate blood groups O and A, sensitization, and body mass index ≥30 kg/m² were independently associated with lower access to transplantation, while female gender, severity of heart failure, and high serum bilirubin levels were independently associated with greater access to transplantation. Center factors significantly associated with access to transplantation were heart donation rate in the donation service area, proportion of high-urgency candidates among listed patients, and donor heart offer decline rate. Between-center variability in access to transplantation increased by 5% after adjustment for candidate factors and decreased by 57% after adjustment for center factors. After adjustment for candidate and center factors, five centers were still outside of normal variability. These findings will be taken into account in the future French heart allocation system.