Cardiac transplant recipients face many complications due to transplant rejection. Scientists must conduct animal experiments to study disease onset mechanisms and develop countermeasures. Therefore, many animal models have been developed for research topics including immunopathology of graft rejection, immunosuppressive therapies, anastomotic techniques, and graft preservation techniques. Small experimental animals include rodents, rabbits, and guinea pigs. They have a high metabolic rate, high reproductive rate, small size for easy handling, and low cost. Additionally, they have genetically modified strains for pathological mechanisms research; however, there is a lacuna, as these research results rarely translate directly to clinical applications. Large animals, including canines, pigs, and non-human primates, have anatomical structures and physiological states that are similar to those of humans; therefore, they are often used to validate the results obtained from small animal studies and directly speculate on the feasibility of applying these results in clinical practice. Before 2023, PubMed Central^® at the United States National Institute of Health’s National Library of Medicine was used for literature searches on the animal models for heart transplantation focusing on the pathological conditions. Unpublished reports and abstracts from conferences were excluded from this review article. We discussed the applications of small- and large-animal models in heart transplantation-related studies. This review article aimed to provide researchers with a complete understanding of animal models for heart transplantation by focusing on the pathological conditions created by each model.

Orthotopic allograft transplantation (OAT) is a major strategy for solid heart and kidney failure. However, the recipient’s immunity-induced chronic rejection induces OAT vasculopathy that results in donor organ failure. With the exception of immunosuppressive agents, there are currently no specific means to inhibit the occurrence of OAT vasculopathy. On the other hand, far-infrared (FIR) therapy uses low-power electromagnetic waves given by FIR, with a wavelength of 3–25 μm, to improve human physiological functions. Previous studies have shown that FIR therapy can effectively inhibit inflammation. It has also been widely used in adjuvant therapy for various clinical diseases, especially cardiovascular diseases, in recent years. Thus, we used this study to explore the feasibility of FIR in preventing OAT vasculopathy. In this study, the model of transplantation of an aorta graft from PVG/Seac rat to ACI/NKyo rat, and in vitro model of human endothelial progenitor cells (EPCs) was used. In this report, we presented that FIR therapy decreased the serious of vasculopathy in OAT-recipient ACI/NKyo rats via inhibiting proliferation of smooth muscle cells, accumulation of collagen, and infiltration of fibroblast in the vessel wall; humoral and cell-mediated immune responses were decreased in the spleen. The production of inflammatory proteins/cytokines also decreased in the plasma. Additionally, FIR therapy presented higher mobilization and circulating EPC levels associated with vessel repair in OAT-recipient ACI/NKyo rats. In vitro studies demonstrated that the underlying mechanisms of FIR therapy inhibiting OAT vasculopathy may be associated with the inhibition of the Smad2-Slug axis endothelial mesenchymal transition (EndoMT). Thus, FIR therapy may be the strategy to prevent chronic rejection-induced vasculopathy.

ScCO₂-decellularized artery graft having tremendous application in vascular regenerative medicine.It with physiological-like responses, including high potential of biocompatibility and long-term patency, lower risk of aneurysm after xenotransplantation.

Background: The extracorporeal life support (ECLS) and temporary bilateral ventricular assist device (t-BiVAD) are commonly applied in patients with cardiogenic shock. Prolonged cardiopulmonary resuscitation (CPR) has poor prognosis. Herein, we report our findings on a combined ECLS and t-BiVAD approach to salvage cardiogenic-shock patients with CPR for more than one hour. Methods: Fifty-nine patients with prolonged CPR and rescued by ECLS and subsequent t-BiVAD were retrospectively collected between January 2015 and December 2019. Primary diagnoses included ischemic, dilated cardiomyopathy, acute myocardial infarction, post-cardiotomy syndrome, and fulminant myocarditis. The mean LVEF was 16.9% ± 6.56% before t-BiVAD. The median ECLS-to-VAD interval is 26 h. Results: A total of 26 patients (44%) survived to weaning, including 13 (22%) bridged to recovery, and 13 (22%) bridged to transplantation. Survivors to discharge demonstrated better systemic perfusion and hemodynamics than non-survivors. The CentriMag-related complications included bleeding (n = 22, 37.2%), thromboembolism (n = 5, 8.4%), and infection (n = 4, 6.7%). The risk factors of mortality included Glasgow Coma Scale (Motor + Eye) ≤ 5, and lactate ≥ 8 mmol/L at POD-1, persistent ventricular rhythm or asystole, and total bilirubin ≥ 6 mg/dL at POD-3. Mortality factors included septic shock (n = 11, 18.6%), central failure (n = 10, 16.9%), and multiple organ failure (n = 12, 20.3%). Conclusions: Combined ECLS and t-BiVAD could be a salvage treatment for patients with severe cardiogenic shock, especially for those already having prolonged CPR. This combination can correct organ malperfusion and allow sufficient time to bridge patients to recovery and heart transplantation, especially in Asia, where donation rates are low, as well as intracorporeal VAD or total artificial heart being seldom available.

Therapeutic elevation of high-density lipoprotein (HDL) is thought to minimize atherogenesis in subjects with dyslipidemia. However, this is not the case in clinical practice. The function of HDL is not determined by its concentration in the plasma but by its specific structural components. We previously identified an index for the prediction of HDL functionality, relative HDL (rHDL) index, and preliminarily explored that dysfunctional HDL (rHDL index value > 2) failed to rescue the damage to endothelial progenitor cells (EPCs). To confirm the effectiveness of the rHDL index for predicting HDL functions, here we evaluated the effects of HDL from patients with different rHDL index values on the endothelial–mesenchymal transition (EndoMT) of EPCs. We also analyzed the lipid species in HDL with different rHDL index values and investigated the structural differences that affect HDL functions. The results indicate that HDL from healthy adults and subjects with an rHDL index value < 2 protected transforming growth factor (TGF)-β1-stimulated EndoMT by modulating Smad2/3 and Snail activation. HDL from subjects with an rHDL index value > 2 failed to restore the functionality of TGF-β1-treated EPCs. Lipidomic analysis demonstrated that HDL with different rHDL index values may differ in the composition of triglycerides, phosphatidylcholine, and phosphatidylinositol. In conclusion, we confirmed the applicability of the rHDL index value to predict HDL function and found structural differences that may affect the function of HDL, which warrants further in-depth studies.

Objective: This study aimed to compare the hemorheological and inflammatory changes before and after coronary artery bypass graft (CABG) surgery, as factors such as hypothermia, hemodilution, transfusion, and other variables affect blood viscosity and inflammation during the procedure. Methods: A total of 25 patients who underwent CABG surgery were enrolled in this study. Whole blood was collected just before the CABG (D₀), 2 days after surgery (D₂), and 5 days after surgery (D₅). The plasma viscosity (PV) and whole blood viscosity (WBV) were measured at shear rates ranging from 0.1 to 1000 s⁻¹ using a rheometer, and the mean values were compared. Inflammatory markers were also assessed and analyzed in relation to the hemorheological changes. Results: Compared with the baseline values, the PV significantly increased after 5 days. WBV showed a significant increase on day 2 and after 5 days. The WBV and fibrinogen were significantly correlated on day 2 and day 5 but not before surgery. Inflammatory markers such as CRP, WBC, platelets, and fibrinogen also demonstrated notable changes in relation to the hemorheological alterations. Conclusions: This study highlights the crucial finding that hyperviscosity, characterized by elevated PV and WBV, persists for almost one week after on-pump CABG surgery. Understanding the interplay between inflammation and hemorheological properties during the postoperative period is crucial for optimizing patient care. Future research should focus on exploring the underlying mechanisms and potential therapeutic interventions to mitigate the impact of inflammation on blood viscosity and improve patient outcomes following CABG surgery.