Enhanced immunosuppression improves early allograft function in a porcine kidney transplant model of donation after circulatory death

Salvaging donated kidneys from prolonged warm ischemia during ex vivo hypothermic oxygenated perfusion

Prolonged warm ischemic is the main cause discarding donated organs after cardiac death. Here, we identified that prolonged warm ischemic time induced disseminated intravascular coagulation and severe capillary vasospasm after cardiac death of rat kidneys. Additionally, we found a significant accumulation of fibrinogen in a hypoxic cell culture of human umbilical vein epithelial cells and in isolated kidneys exposed to prolonged warm ischemic following flushing out of blood. However, pre-flushing the kidney with snake venom plasmin in a 90-minute warm ischemic model maximized removal of micro thrombi and facilitated the delivery of oxygen and therapeutic agents. Application of carbon monoxide-releasing CORM-401 during ex vivo hypothermic oxygenated perfusion achieved multipath protective effects in prolonged warm ischemic kidneys. This led to significant improvements in perfusion parameters, restoration of the microcirculation, amelioration of mitochondrial injury, oxidative stress, and apoptosis. This benefit resulted in significantly prolonged warm ischemic kidney recipient survival rates of 70%, compared with none in those receiving ex vivo hypothermic oxygenated perfusion alone. Significantly, ex vivo hypothermic oxygenated perfusion combined with cytoprotective carbon monoxide releasing CORM-401 treatment meaningfully protected the donated kidney after cardiac death from ischemia-reperfusion injury by reducing inflammation, oxidative stress, apoptosis, and pathological damage. Thus, our study suggests a new combination treatment strategy to potentially expand the donor pool by increasing use of organs after cardiac death and salvaging prolonged warm ischemic kidneys.

Administration of adipose stromal vascular fraction attenuates acute rejection in donation after circulatory death rat renal transplantation

OBJECTIVE

Stem cell therapy represents a new approach to induce immune tolerance in solid organ transplantation. However, the time-consuming process of stem cell expending limits the range of stem cell treatment. Uncultured adipose stromal vascular fraction is considered an attractive cell source for cell-based therapy. This study aimed to evaluate the effect of stromal vascular fraction on the immune system in donation after circulatory death rat renal transplantation.

METHODS

Stromal vascular fraction cells and splenocytes were co-cultured to evaluate the effect of stromal vascular fraction on splenocyte proliferation and viability. Sprague-Dawley rats were used as donors. and Wistar rats as recipients to establish a donation after a circulatory death rat renal transplantation model. Warm ischemia time was 5 min. Stromal vascular fraction was administered in the rat model following the intra-arterial route. The spleens and grafts of recipients were harvested on days 1, 3 and 7 post-transplantation for assessing acute rejection, infiltration of inflammatory cells, indoleamine 2, 3-dioxygenase expression and T-cell frequency in the spleen.

RESULTS

Stromal vascular fraction could inhibit proliferation and induce apoptosis of splenocytes in vitro (P < 0.05). The administration of stromal vascular fraction could significantly reduce acute rejection and infiltration of CD8⁺ T cells and mononuclear macrophages in grafts, and increase indoleamine 2, 3-dioxygenase expression (P < 0.05). The frequency of CD8⁺ T cells decreased, and the frequency of CD25⁺ Foxp3⁺ regulatory T cells increased in the spleen of the acute rejection + stromal vascular fraction group on day 7 post-transplantation (P < 0.05).

CONCLUSION

Administration of the adipose stromal vascular fraction could attenuate acute rejection in donation after circulatory death renal transplantation by increasing the ratio of regulatory T cells and enhancing indoleamine 2, 3-dioxygenase expression.

Dual Lactate Clearance in the Viability Assessment of Livers Donated After Circulatory Death With Ex Situ Normothermic Machine Perfusion

Supplemental Digital Content is available in the text.

Perfusate lactate clearance (LC) is considered one of the useful indicators of liver viability assessment during normothermic machine perfusion (NMP); however, the applicable scope and potential mechanisms of LC remain poorly defined in the setting of liver donation after circulatory death.

Prolonged warm ischemia time leads to severe renal dysfunction of donation-after-cardiac death kidney grafts

Kidney transplantation with grafts procured after donation-after-cardiac death (DCD) has led to an increase in incidence of delayed graft function (DGF). It is thought that the warm ischemic (WI) insult encountered during DCD procurement is the cause of this finding, although few studies have been designed to definitely demonstrate this causation in a transplantation setting. Here, we use a large animal renal transplantation model to study the effects of prolonged WI during procurement on post-transplantation renal function. Kidneys from 30 kg-Yorkshire pigs were procured following increasing WI times of 0 min (Heart-Beating Donor), 30 min, 60 min, 90 min, and 120 min (n = 3-6 per group) to mimic DCD. Following 8 h of static cold storage and autotransplantation, animals were followed for 7-days. Significant renal dysfunction (SRD), resembling clinical DGF, was defined as the development of oliguria < 500 mL in 24 h from POD3-4 along with POD4 serum potassium > 6.0 mmol/L. Increasing WI times resulted in incremental elevation of post-operative serum creatinine that peaked later. DCD120min grafts had the highest and latest elevation of serum creatinine compared to all groups (POD5: 19.0 ± 1.1 mg/dL, p < 0.05). All surviving animals in this group had POD4 24 h urine output < 500 cc (mean 235 ± 172 mL) and elevated serum potassium (7.2 ± 1.1 mmol/L). Only animals in the DCD120min group fulfilled our criteria of SRD (p = 0.003), and their renal function improved by POD7 with 24 h urine output > 500 mL and POD7 serum potassium < 6.0 mmol/L distinguishing this state from primary non-function. In a transplantation survival model, this work demonstrates that prolonging WI time similar to that which occurs in DCD conditions contributes to the development of SRD that resembles clinical DGF.