The shortage of organs available for transplantation remains a global problem that will increase as life expectancy continues to rise.

Whole organ perfusion decellularisation is a technique designed for the generation of non-immunogenic organs from allogeneic or xenogeneic donors. Decellularisation is used to remove the cellular content of an organ, leaving behind an extracellular matrix (ECM) with preserved microstructure, biochemical composition and cell-instructive signals (Figure 1) without immunogenicity, meaning it can be available to everyone.

Figure 1: Gross appearance (top row) and histological examination (bottom row) of native (left column) and decellularised kidneys (right column). Scale bar: 100µm (Cohen et al, 2019).

Successful utilisation of this technique depends on the integrity of the organ’s vasculature. The organ’s native vascular tree is first used to circulate detergent-based solutions that dissolve cells and wash away cellular antigens and DNA. The native vasculature is also used to repopulate the organ with non-immunogenic, preferably recipient-derived cells and to deliver cell culture media to support cell viability and differentiation.

Thus, it is crucial to maintain the integrity throughout the different steps of the organ manufacturing process, to ensure that no vascular damage has occurred and that decellularised vessels regain functionality.

The goal of our study was to propose that fluoroscopic angiography under controlled flow conditions can be used to assess the arterial and venous integrity in a reliable and accessible manner.

Our hospital is the leading centre for transplantation in Israel; extensive research is being conducted in this field with an emphasis on decellularised organs and their re-population with patient-derived cells. Part of the research is the imaging and assessment of these organs; thus, the Department of Organ Transplantation and the Department of Radiology joined forces to evaluate the new developing organs.

Harvested porcine kidneys underwent ex vivo fluoroscopic angiography before and after the perfusion decellularisation process, under controlled flow conditions.

Arterial and venous patency were defined as visualisation of contrast medium (CM) in distal capillaries and renal vein, respectively (Figure 2). For permeability assessment, greyscale intensity within the parenchyma was measured and washout index (Windex) was calculated at several time points during a washout phase.

Figure 2: Arterial patency in decellularised kidneys – representative sequential fluoroscopic and corresponding DSA. Note normal branching of the renal artery into segmental, lobar, interlobar and arcuate arteries (Cohen et al, 2019).

We found no differences in patency among decellularised kidneys compared to native kidneys.

However, significantly lower Windex was calculated for decellularised kidneys, indicating delayed CM clearance and increased vascular permeability (Figure 3). We also demonstrated focal parenchymal opacities representing extravasation of CM into the parenchymal tissue. These findings were only detected in decellularised kidneys.

Figure 3: Vascular permeability. Representative fluoroscopic images of CM washout at t=0, t=5 and t=10 min in native kidneys (top row) and decellularised kidneys (middle row) (Cohen et al, 2019). Graph shows lower Windex indicating decreased CM clearance in decellularised kidneys compared with native kidneys, * p<0.05.

In summary, quantitative assessment of vascular permeability should be coupled with patency when studying the effect of perfusion decellularisation on kidney vasculature. Flow-controlled fluoroscopic angiography based on the proposed methodology is an accessible, accurate and sensitive method that should be adopted as method-of-choice for evaluation of vascular integrity in bioengineered organs.

Our findings provide important information for the development of bioengineered organs.

Dr. Sarit Hirschberg is a 3rd year radiology resident at Rabin Medical Center in Israel.

Research Presentation Session
RPS 1415 Advances in vascular imaging

Flow-controlled angiography for the assessment of vascular patency, permeability, and leakage in bioengineered kidneys
S. Cohen1, S. Hirschberg2, S. Partouche1, M. Gurevich1, V. Tennak1, V. Mezhybovsky1, E. Nesher1, E. Mor3, E. Atar1; 1Petah Tikva/IL, 2Salit/IL, 3Ramat Gan/IL

Read the full abstract in the ECR 2020 Book of Abstracts
Hirschberg S, et al. (2020) Flow-controlled angiography for the assessment of vascular patency, permeability, and leakage in bioengineered kidneys. Abstract RPS 1415-1 in: ECR 2020 Book of Abstracts. Insights Imaging 11, 34 (2020). DOI 10.1186/s13244-020-00851-0