Rapid or Slow Time to Brain Death? Impact on Kidney Graft Injuries in an Allotransplantation Porcine Model

Cascading renal injury after brain death: Unveiling glycocalyx alteration and the potential protective role of tacrolimus

Brain death (BD) is a complex medical state that triggers systemic disturbances and a cascade of pathophysiological processes. This condition significantly impairs both kidney function and structural integrity, thereby presenting considerable challenges to graft viability and the long-term success of transplantation endeavors. Tacrolimus (FK506), an immunosuppressive drug, was used in this study to assess its impact as a pretreatment on brain death-induced renal injury. This study aimed to investigate changes associated with brain death-induced renal injury in a 4-month-old female porcine model. The experimental groups included brain death placebo-pretreated (BD; n = 9), brain death tacrolimus-pretreated using the clinical dose of 0.25 mg/kg the day before surgery, followed by 0.05 mg/kg/day 1 hour before the procedure (BD + FK506; n = 8), and control (ctrl, n = 7) piglets, which did not undergo brain death induction. Furthermore, we aimed to assess the effect of FK506 on these renal alterations through graft preconditioning. We hypothesized that immunosuppressive properties of FK506 reduce tissue inflammation and preserve the glycocalyx. Our findings revealed a series of interconnected events triggered by BD, leading to a deterioration of renal function and increased proteinuria, increased apoptosis in the vessels, glomeruli and tubules, significant leukocyte infiltration into renal tissue, and degradation of the glycocalyx in comparison with ctrl group. Importantly, treatment with FK506 demonstrated significant efficacy in attenuating these adverse effects. FK506 helped reduce apoptosis, maintain glycocalyx integrity, regulate neutrophil infiltration, and mitigate renal injury following BD. This study offers new insights into the pathophysiology of BD-induced renal injury, emphasizing the potential of FK506 pretreatment as a promising therapeutic intervention for organ preservation, through maintaining endothelial function with the additional benefit of limiting the risk of rejection.

Improvement of a Model of Brain Death for Transplant-Associated Studies in Rats

BACKGROUND

The most common method of inducing brain death in rats is inflating an intracranially placed balloon of a Fogarty catheter inserted through a burr hole. However, because of the poor controllability of balloon position, the standardization and stability of the model are compromised. This study examined an improved technique in which the balloon is placed and fixed through double holes.

METHODS

Forty adult male Sprague-Dawley (SD) rats were randomly and equally assigned into the single-hole (SH) group and the double-hole (DH) group. In each rat in the DH group, 2 holes were made, at the left frontal bone and parietal bone. A Fogarty catheter was inserted outside of the dura mater through the frontal hole, and its tip was guided out through the parietal hole using an arc-shaped needle. The SH group served as a control. In both groups, normal saline was injected into the balloon at 40 μL/minute until breathing stopped. Mechanical ventilation was instituted immediately and provided for another 6 hours after the determination of brain death.

RESULTS

Typical blood pressure patterns were observed in both groups during the brain death induction period, whereas the fluctuation seemed relatively mild in the DH group. Stable brain death with normotension for 6 hours was induced successfully in 18 rats (90%) in the DH group and in 9 rats (45%) in the SH group (P = .002). The mean arterial pressure at 3 hours and thereafter was significantly higher in the DH group compared to the SH group (P < .05).

CONCLUSIONS

Our results demonstrate that the DH method is a simple and effective technique to make the brain death model more stable and standardized, possibly due to precise control of the direction of the cannulation and the position of the balloon.

Considerations for the use of porcine organ donation models in preclinical organ donor intervention research

Use of animal models in preclinical transplant research is essential to the optimization of human allografts for clinical transplantation. Animal models of organ donation and preservation help to advance and improve technical elements of solid organ recovery and facilitate research of ischemia-reperfusion injury, organ preservation strategies, and future donor-based interventions. Important considerations include cost, public opinion regarding the conduct of animal research, translational value, and relevance of the animal model for clinical practice. We present an overview of two porcine models of organ donation: donation following brain death (DBD) and donation following circulatory death (DCD). The cardiovascular anatomy and physiology of pigs closely resembles those of humans, making this species the most appropriate for pre-clinical research. Pigs are also considered a potential source of organs for human heart and kidney xenotransplantation. It is imperative to minimize animal loss during procedures that are surgically complex. We present our experience with these models and describe in detail the use cases, procedural approach, challenges, alternatives, and limitations of each model.

Astragaloside IV Ameliorates Streptozotocin Induced Pancreatic β-Cell Apoptosis and Dysfunction Through SIRT1/P53 and Akt/GSK3β/Nrf2 Signaling Pathways

BACKGROUND

Absolute or relative lack of insulin secretion caused by pancreatic β-cell dysfunction can lead to diabetes. Astragaloside IV (AS-IV), the main components of the traditional Chinese medicine Astragalus, has anti-oxidant, anti-inflammatory and anti-apoptotic properties, and exerts anti-diabetic pharmacological effects.

PURPOSE

To explore whether AS-IV can protect the apoptosis and dysfunction of pancreatic β-cells induced by streptozotocin (STZ) and its underlying molecular mechanism.

METHODS

STZ-induced pancreatic β-cell line INS-1 was treated with different concentrations of AS-IV, then cell viability, apoptosis, oxidative stress and insulin secretion was assessed by CCK-8, TUNEL staining, Western blot, commercial kits and qRT-PCR, respectively. The expression of proteins involved in Sirtuin 1 (SIRT1)/p53 and Akt/glycogen synthase kinase-3 β (GSK3β)/nuclear factor E2-related factor 2 (Nrf2) signaling was measured by Western blot assay. Besides, Akt inhibitor MK-2206 and SIRT1 inhibitor EX-527 were used to co-treat STZ-induced INS-1 cells in the presence of AS-IV, and the above experiments were repeated.

RESULTS

AS-IV increased the cell viability of INS-1 cells induced by STZ. AS-IV also reduced the increase in apoptosis rate and reversed STZ-induced down-regulation of Bcl-2 and up-regulation of Bax and Cleaved caspase 3. In addition, AS-IV significantly reduced STZ-induced malondialdehyde upregulation and reduced superoxide dismutase and glutathione peroxidase levels. Furthermore, the use of AS-IV was found to increase the insulin secretion capacity of INS-1 cells with impaired function, along with the increase of the mRNA levels of insulin 1 and insulin 2. Mechanism studies further showed that MK-2206 and EX-527 reversed the protective effect of AS-IV against STZ-induced injury on INS-1 cells.

CONCLUSION

AS-IV exerted cytoprotective effect on STZ-induced INS-1 cells through regulating SIRT1/p53 and Akt/GSK3β/Nrf2 signaling pathways. These findings are expected to provide new supplements to the molecular mechanism of AS-IV in the treatment of diabetes.

The inhibition of eIF5A hypusination by GC7, a preconditioning protocol to prevent brain death-induced renal injuries in a preclinical porcine kidney transplantation model

The eIF5A hypusination inhibitor GC7 (N1-guanyl-1,7-diaminoheptane) was shown to protect from ischemic injuries. We hypothesized that GC7 could be useful for preconditioning kidneys from donors before transplantation. Using a preclinical porcine brain death (BD) donation model, we carried out in vivo evaluation of GC7 pretreatment (3 mg/kg iv, 5 minutes after BD) at the beginning of the 4h-donor management, after which kidneys were collected and cold-stored (18h in University of Wisconsin solution) and 1 was allotransplanted. Groups were defined as following (n = 6 per group): healthy (CTL), untreated BD (Vehicle), and GC7-treated BD (Vehicle + GC7). At the end of 4h-management, GC7 treatment decreased BD-induced markers, as radical oxygen species markers. In addition, GC7 increased expression of mitochondrial protective peroxisome proliferator-activated receptor-gamma coactivator-1-alpha (PGC1α) and antioxidant proteins (superoxyde-dismutase-2, heme oxygenase-1, nuclear factor [erythroid-derived 2]-like 2 [NRF2], and sirtuins). At the end of cold storage, GC7 treatment induced an increase of NRF2 and PGC1α mRNA and a better mitochondrial integrity/homeostasis with a decrease of dynamin- related protein-1 activation and increase of mitofusin-2. Moreover, GC7 treatment significantly improved kidney outcome during 90 days follow-up after transplantation (fewer creatininemia and fibrosis). Overall, GC7 treatment was shown to be protective for kidneys against BD-induced injuries during donor management and subsequently appeared to preserve antioxidant defenses and mitochondria homeostasis; these protective effects being accompanied by a better transplantation outcome.

Evaluation of Liver Quality after Circulatory Death Versus Brain Death: A Comparative Preclinical Pig Model Study

The current organ shortage in hepatic transplantation leads to increased use of marginal livers. New organ sources are needed, and deceased after circulatory death (DCD) donors present an interesting possibility. However, many unknown remains on these donors and their pathophysiology regarding ischemia reperfusion injury (IRI). Our hypothesis was that DCD combined with abdominal normothermic regional recirculation (ANOR) is not inferior to deceased after brain death (DBD) donors. We performed a mechanistic comparison between livers from DBD and DCD donors in a highly reproducible pig model, closely mimicking donor conditions encountered in the clinic. DCD donors were conditioned by ANOR. We determined that from the start of storage, pro-lesion pathways such as oxidative stress and cell death were induced in both donor types, but to a higher extent in DBD organs. Furthermore, pro-survival pathways, such as resistance to hypoxia and regeneration showed activation levels closer to healthy livers in DCD-ANOR rather than in DBD organs. These data highlight critical differences between DBD and DCD-ANOR livers, with an apparent superiority of DCD in terms of quality. This confirms our hypothesis and further confirms previously demonstrated benefits of ANOR. This encourages the expended use of DCD organs, particularly with ANOR preconditioning.