A central arteriovenous fistula reduces systemic hypertension in a mouse model.

Objective: A central arteriovenous fistula (AVF) has been proposed as a potential novel solution to treat patients with refractory hypertension. We hypothesized that venous remodeling after AVF creation in the hypertensive environment reduces systemic blood pressure but results in increased AVF wall thickness compared with remodeling in the normotensive environment. Methods: A central AVF was performed in C57BL6/J mice previously made hypertensive with angiotensin II (Ang II); mice were sacrificed on postoperative day 7 or 21. Results: In mice treated with Ang II alone, the mean systolic blood pressure increased from 90 ± 5 mmHg to 160 ± 5 mmHg at day 21; however, in mice treated with both Ang II and an AVF, the blood pressure decreased with creation of an AVF. There were significantly more PCNA-positive cells, SM22α/PCNA-positive cells, collagen I deposition, and increased Krüppel-like Factor 2 immunoreactivity in hypertensive mice with an AVF compared with normotensive mice with an AVF. Conclusions: These data show that a central AVF decreases systemic hypertension as well as induces local alterations in venous remodeling.

EphB4 monomer inhibits chronic graft vasculopathy in an aortic transplant model.

T cells and macrophages play an important role in the formation of allograft vasculopathy, which is the predominant form of chronic rejection in cardiac transplants. Arteries express Ephrin-B2 as a marker of arterial identity, whereas circulating monocytes express the cognate receptor EphB4, which facilitates monocyte adhesion to the endothelial surface. Adherent monocytes transmigrate and differentiate into macrophages that activate T cells and are a main source of tissue damage during rejection. We hypothesized that inhibition of Ephrin-B2-EphB4 binding would decrease immune cell accumulation within a transplanted graft and prevent allograft vasculopathy. We used EphB4 monomer to inhibit Ephrin-B2-EphB4 binding in a rat infrarenal aortic transplant model. Rats treated with EphB4 monomer had fewer macrophages and T cells in the aortic allografts at 28 days, as well as significantly less neointima formation. These data show that the Ephin-B2-EphB4 axis may be an important target for prevention or treatment of allograft vasculopathy.

Transplant Fellowship and Presenting at a Transplant-Specific Conference.

INTRODUCTION: The ASTS implemented a task force in 2018 to increase residents' interest in careers in organ transplantation. National meetings offer important experiences that can increase interest. The present study examines an association that exists between presenting at a major transplant surgery meeting and a trainee's likelihood of pursuing a career in transplant surgery. METHODS: All abstracts from the ASTS State of the Art Winter Symposium from 2010 to 2019 were evaluated. Using a combination of internet-based resources, it was determined if the presenter was a resident, what year of residency they were in, and if that individual went into a transplant fellowship. RESULTS: 1544 abstracts were reviewed and 133 were presented by residents. Out of residents that presented, 68.4% (54/79) were senior residents and 31.6% (25/79) were junior residents. Of senior residents, 66.7% (36/54) went into transplant fellowships, while only 20.0% (5/25) of junior residents went into transplant fellowships. Being a senior resident when presenting was statistically significant for pursuing a transplant fellowship (P = .000113). DISCUSSION: Senior residents who present at ASTS SAWS are likely to pursue a transplant surgery fellowship. Junior residents who present are less likely to pursue transplantation, and this represents an opportunity to improve the engagement of young surgeons in the specialty.

Revisiting the Principles of Preservation in an Era of Pandemic Obesity.

The current obesity epidemic has caused a significant decline in the health of our donor population. Organs from obese deceased donors are more prone to ischemia reperfusion injury resulting from organ preservation. As a consequence, these donors are more likely to be discarded under the assumption that nothing can be done to make them viable for transplant. Our current methods of organ preservation-which remain relatively unchanged over the last ~40 years-were originally adopted in the context of a much healthier donor population. But methods that are suitable for healthier deceased donors are likely not optimal for organs from obese donors. Naturally occurring models of acute obesity and fasting in hibernating mammals demonstrate that obesity and resilience to cold preservation-like conditions are not mutually exclusive. Moreover, recent advances in our understanding of the metabolic dysfunction that underlies obesity suggest that it may be possible to improve the resilience of organs from obese deceased donors. In this mini-review, we explore how we might adapt our current practice of organ preservation to better suit the current reality of our deceased donor population.