Simply Adding Oxygen during Hypothermic Machine Perfusion to Combat the Negative Effects of Ischemia-Reperfusion Injury: Fundamentals and Current Evidence for Kidneys

The use of high-risk renal grafts for transplantation requires optimization of pretransplant preservation and assessment strategies to improve clinical outcomes as well as to decrease organ discard rate. With oxygenation proposed as a resuscitative measure during hypothermic machine preservation, this review provides a critical overview of the fundamentals of active oxygenation during hypothermic machine perfusion, as well as the current preclinical and clinical evidence and suggests different strategies for clinical implementation.

Dendritic Cells: Versatile Players in Renal Transplantation

Dendritic cells (DCs) induce and regulate adaptive immunity through migrating and maturing in the kidney. In this procedure, they can adopt different phenotypes—rejection-associated DCs promote acute or chronic injury renal grafts while tolerogenic DCs suppress the overwhelmed inflammation preventing damage to renal functionality. All the subsets interact with effector T cells and regulatory T cells (Tregs) stimulated by the ischemia–reperfusion procedure, although the classification corresponding to different effects remains controversial. Thus, in this review, we discuss the origin, maturation, and pathological effects of DCs in the kidney. Then we summarize the roles of divergent DCs in renal transplantation: taking both positive and negative stages in ischemia–reperfusion injury (IRI), switching phenotypes to induce acute or chronic rejection, and orchestrating surface markers for allograft tolerance via alterations in metabolism. In conclusion, we prospect that multidimensional transcriptomic analysis will revolute researches on renal transplantation by addressing the elusive mononuclear phagocyte classification and providing a holistic view of DC ontogeny and subpopulations.

Aberrant activation of complement system in renal grafts is mediated by cold storage

Aberrant complement activation leads to tissue damage during kidney transplantation, and it is recognized as an important target for therapeutic intervention (6, 19, 35, 64). However, it is not clear whether cold storage (CS) triggers the complement pathway in transplanted kidneys. The goal of this study was to determine the impact of CS on complement activation in renal transplants. Male Lewis and Fischer rats were used, and donor rat kidneys were exposed to 4 h or 18 h of CS followed by transplantation (CS+Transplant). To study CS-induced effects, a group with no CS was included in which the kidney was removed and transplanted back to the same rat (autotransplantation, ATx). Complement proteins (C3 and C5b-9) were evaluated with western blotting (reducing and non-reducing conditions) and immunostaining. Western blot of renal extracts or serum indicated that the levels of C3 and C5b-9 increased after CS+Transplant compared to ATx. Quite strikingly, intracellular C3 was profoundly elevated within renal tubules after CS+Transplant but was absent in Sham or ATx groups, which showed only extratubular C3. Similarly, C5b-9 immunofluorescence staining of renal sections showed an increase in C5b-9 deposits in kidneys after CS+Transplant. Real-time PCR (SYBR Green) showed increased expression of CD11b and CD11c, components of complement receptors 3 and 4, respectively, as well as inflammatory markers such as TNF-α. In addition, recombinant TNF-α significantly increased C3 levels in renal cells. Collectively, these results demonstrate that CS activates the complement system in renal transplants.

Candida Contamination in Kidney and Liver Organ Preservation Solution: Does It Matter?

Introduction: Fungal infections remain a major challenge affecting outcomes after kidney (KT) and liver transplantation (LT). Methods: In this retrospective single center study, the incidence of Candida contamination in renal and hepatic graft preservation solution (PS) was evaluated. In addition, Candida associated infections in recipients and related complications were analyzed. Results: Overall, the PS of 1248 hepatic and 1273 renal grafts were evaluated. The incidence of fungal contamination in the PS of hepatic and renal grafts was 1.2% and 0.86%, respectively. Additionally, the hepatic PS of one patient who underwent a combined liver–kidney transplant had Candida contamination. Candida albicans was the most common organism (70.4%) and 65.4% of the patients received antifungal treatment. Candida-associated complications in the recipients was 19%. Complications in LT patients included Candida peritonitis and Candida sepsis. Two KT recipients with contaminated PS developed a mycotic aneurysm at the anastomotic site resulting in severe bleeding. The 1-year mortality in patients with PS contamination for LT and KT recipients was 33% and 18%, respectively. Although the incidence of fungal contamination of PS was low, contaminated PS was associated with a high mortality. Conclusion: The results of the study suggest that PS should be evaluated for fungal growth.

Outcomes of Renal Stone Surgery Performed Either as Predonation or Ex Vivo Bench Procedure in Renal Grafts from Living Donors: A Systematic Review

Aims. We aimed to summarize available evidence about intraoperative and postoperative donors’ and recipients’ outcomes following stone surgery in renal grafts from living donors performed either before donation or as ex vivo bench surgery at the time of living-donor nephrectomy. Methods. A systematic review of PubMed, ISI Web of Knowledge, and Scopus databases was performed in September 2020. We included full papers that met the following criteria: original research, English language, human studies, and describing the results of stone surgery in renal grafts from living donors performed either before transplantation or as ex vivo bench surgery. Results. We identified 11 studies involving 106 patients aged between 22 and 72 years. Predonation and bench stone surgery was performed in 9 (8.5%) and 96 (90.6%) patients, respectively. Predonation stone surgery involved extracorporeal shock wave lithotripsy, retrograde intrarenal surgery, and percutaneous nephrolithotomy in 8, 1, and 1 patient, respectively. The overall success rate of predonation stone surgery was 78%, and the complication rate was 0%. Bench stone surgery involved ureteroscopy, pyelolithotomy, or a combination of both in 79 (82.3%), 10 (10.4%), and 7 (7.3%) cases, respectively, with an overall success rate of 95.8% and an overall complication rate of 9.37%. Conclusions. Predonation and bench stone surgery in grafts from living donors represents efficacious and safe procedures. Further studies on wider series with a longer follow-up are required.