A novel extracorporeal kidney perfusion system: a concept model

Congenital pelvic kidney perfusion during infrarenal aortic aneurysm repair

Purpose: This case report describes a patient with a pelvic kidney associated with an aortoiliac aneurysm amenable to open repair. Methods: We chose the selective cold renal perfusion to preserve renal function. Results: Other techniques such as transient or permanent extra-anatomic bypass, extracorporeal circulation and proximal aortic double clamping are also described in this report. Conclusions: Choosing the renal perfusion technique depended on the anatomical evaluations of the kidney and the renal artery location during the preoperative period.

Vascular reconstruction: A major challenge in developing a functional whole solid organ graft from decellularized organs

Bioengineering a functional organ holds great potential to overcome the current gap between the organ need and shortage of available organs. Whole organ decellularization allows the removal of cells from large-scale organs, leaving behind extracellular matrices containing different growth factors, structural proteins, and a vascular network with a bare surface. Successful application of decellularized tissues as transplantable organs is hampered by the inability to completely reline the vasculature by endothelial cells (ECs), leading to blood coagulation, loss of vascular patency, and subsequent death of reseeded cells. Therefore, an intact, continuous layer of endothelium is essential to maintain proper functioning of the vascular system, which includes the transfer of nutrients to surrounding tissues and protecting other types of cells from shear stress. Here, we aimed to summarize the available cell sources that can be used for reendothelialization in addition to different trials performed by researchers to reconstruct vascularization of decellularized solid organs. Additionally, different techniques for enhancing reendothelialization and the methods used for evaluating reendothelialization efficiency along with the future prospective applications of this field are discussed. STATEMENT OF SIGNIFICANCE: Despite the great progress in whole organ decellularization, reconstruction of vasculature within the engineered constructs is still a major roadblock. Reconstructed endothelium acts as a multifunctional barrier of vessels, which can reduce thrombosis and help delivering of oxygen and nutrients throughout the whole organ. Successful reendothelialization can be achieved through reseeding of appropriate cell types on the naked vasculature with or without modification of its surface. Here, we present the current research milestones that so far established to reconstruct the vascular network in addition to the methods used for evaluating the efficiency of reendotheilization. Thus, this review is quite significant and will aid the researchers to know where we stand toward biofabricating a transplantable organ from decellularizd extracellular matrix.

Biomarkers assessing warm ischemic injury using an isolated porcine kidney hemoreperfusion model

Prolonged warm ischemia (WI) occurring in marginal kidney donors together with reperfusion injury determines allograft survival, in which apoptosis and inflammation play crucial roles. There is no single valid biomarker, so far, to assess the degree of kidney donor injury. To define new biomarkers for detecting initial donor ischemic injury, caspase-3, caspase-7, apoptosis, inflammation, HSP70 and renal histological changes were examined in porcine kidneys subjected to 7- 15- 25- or 40-min WI, two-hour cold storage and six-hour hemoreperfusion. Caspase-3 activity was gradually increased by prolonged reperfusion, with a decrease trend against WI time. This result was verified by raised 17 kDa active caspase-3 in postreperfusion kidneys, with elevated 12 kDa active caspase-3 and lowered precursor at seven-minute WI. Active caspase-7 was also doubled by reperfusion with decreased precursor at seven-minute WI, but declined against prolonged WI. Apoptotic cells in tubular and interstitial areas were greatly increased by reperfusion at seven-minute WI, but decreased against prolonged WI. In addition, myeloperoxidase (MPO)+ cells were dramatically increased by reperfusion and presented as a bell-shape against WI time, while HSP70 was significantly increased at 7-min WI, but decreased at 40-min WI after reperfusion. In postreperfusion kidneys, tubular dilation and cell shedding were observed at 7- and 15-min WI, while tubular vacuolation and cell debris were found in tubular lumens at longer WI times. At 40-min WI, early nuclear pyknosis, tubular epithelia detachment and peri-tubular capillary dilation were detected. Furthermore, caspase-3, caspase-7, apoptosis, but not MPO+ cells or HSP70, were correlated with renal function. In conclusion, caspase-3, caspase-7 and apoptosis appear to be better biomarkers than MPO+ cells or HSP70 for assessing warm ischemic injury in donor kidneys. Hemoreperfusion activates caspase-3 and caspase-7, promotes apoptosis of damaged cells in kidneys only with limited WI, which might be beneficial to renal structural re-modeling and functional recovery.

Leucocyte depletion improves renal function in porcine kidney hemoreperfusion through reduction of myeloperoxidase+ cells, caspase-3, IL-1β, and tubular apoptosis

BACKGROUND

Leucocytes play crucial roles in ischemia reperfusion injury that is inevitable in kidney transplantation. Leucocyte-depleted hemoreperfusion improved post-ischemic renal function was demonstrated in our previous study and its underlying mechanisms were further investigated in this study.

METHODS

Porcine kidneys were subjected to 7 min warm ischemia and 2 h cold storage, and preserved by hemoreperfusion with or without leucocyte depletion for 6 h on an isolated organ perfusion system.

RESULTS

Tubulointerstitial damage was improved by leucocyte depletion, which was accompanied by reduced myeloperoxidase+ cell infiltration up to 91%. Apoptotic cells in tubular and interstitial areas were increased by hemoreperfusion, but tubular apoptosis was decreased by leucocyte depletion. The raised caspase-3 activity by hemoreperfusion was almost completely abolished by leucocyte depletion. In addition, the expression of IL-1β active subunit was enhanced by hemoreperfusion, but partially reduced by leucocyte depletion, although IL-1β precursor and HSP70 were increased by hemoreperfusion regardless of leucocyte depletion. Furthermore, myeloperoxidase+ cells were associated with caspase-3 activity, both of which were positively correlated with tubular apoptosis, IL-1β active subunit, tubulointerstitial damage, and serum creatinine, while HSP70 was linked to renal blood flow.

CONCLUSIONS

Leucocyte depletion improved post-ischemic renal function and structure was mainly due to reduced infiltration of myeloperoxidase+ cells, which was associated with decreased apoptosis, caspase-3 activity and IL-1β activation.