Development of a Novel Perfusable Solution for ex vivo Preservation: Towards Photosynthetic Oxygenation for Organ Transplantation.

Valentina Veloso-Giménez,Sergio Riveros,Rocío Corrales-Orovio,Carlo Marino,Mauricio P Boric,David Necuñir,Rosalba Escamilla,Carolina Ehrenfeld,José Tomás Egaña,Rolando Rebolledo,Christian Dani Guzmán

doi:10.3389/fbioe.2021.796157

Abstract

Oxygen is the key molecule for aerobic metabolism, but no animal cells can produce it, creating an extreme dependency on external supply. In contrast, microalgae are photosynthetic microorganisms, therefore, they are able to produce oxygen as plant cells do. As hypoxia is one of the main issues in organ transplantation, especially during preservation, the main goal of this work was to develop the first generation of perfusable photosynthetic solutions, exploring its feasibility for ex vivo organ preservation. Here, the microalgae Chlamydomonas reinhardtii was incorporated in a standard preservation solution, and key aspects such as alterations in cell size, oxygen production and survival were studied. Osmolarity and rheological features of the photosynthetic solution were comparable to human blood. In terms of functionality, the photosynthetic solution proved to be not harmful and to provide sufficient oxygen to support the metabolic requirement of zebrafish larvae and rat kidney slices. Thereafter, isolated porcine kidneys were perfused, and microalgae reached all renal vasculature, without inducing damage. After perfusion and flushing, no signs of tissue damage were detected, and recovered microalgae survived the process. Altogether, this work proposes the use of photosynthetic microorganisms as vascular oxygen factories to generate and deliver oxygen in isolated organs, representing a novel and promising strategy for organ preservation.

Highlights

The lack of appropriate tissue oxygenation represents a major issue in several medical areas, being relevant in the transplantation field, where organ ischemia induces hypoxia, limiting their ex vivo preservation time, as well as their further clinical outcome after transplantation (Hosgood et al, 2012; Giwa et al, 2017).Aiming to decrease the oxygen requirements of isolated organs, static cold storage (SCS) has been the gold standard in clinical transplantation settings, reducing metabolism and oxygenPhotosynthesis for Organ Preservation consumption in about 90% (Karangwa et al, 2016)
This technique is limited in terms of preservation time and for maintaining the integrity of suboptimal grafts derived from expanded criteria donor (ECD) and donation after circulatory death (DCD), which are more sensitive to damage (Soo et al, 2020; Vries et al, 2020)
Results show that glomeruli and tubules did not present signs of damage, as neither necrotic cells in Bowman’s capsule nor blood cells or microalgae in Bowman’s space were detected. In this proof-of-concept study, we demonstrate the feasibility to incorporate photosynthetic microorganisms in organ perfusion solutions to provide an alternative intravascular source of oxygen to isolated organs

Summary

Introduction

The lack of appropriate tissue oxygenation represents a major issue in several medical areas, being relevant in the transplantation field, where organ ischemia induces hypoxia, limiting their ex vivo preservation time, as well as their further clinical outcome after transplantation (Hosgood et al, 2012; Giwa et al, 2017).Aiming to decrease the oxygen requirements of isolated organs, static cold storage (SCS) has been the gold standard in clinical transplantation settings, reducing metabolism and oxygenPhotosynthesis for Organ Preservation consumption in about 90% (Karangwa et al, 2016). Photosynthetic therapies aim to generate a local symbiotic relationship between animal and photosynthetic cells where, in the presence of light, both metabolisms could be coupled with each other (Chávez et al, 2020) This approach has been described by our group in recent in vitro (Hopfner et al, 2014; Centeno-Cerdas et al, 2018; Chávez et al, 2021) and in vivo (Schenck et al, 2015; Chávez et al, 2016) studies, and further confirmed by other independent groups, highlighting its potential application in several medical fields, including tissue engineering and regeneration (Yamaoka et al, 2012; Evron et al, 2015; Haraguchi et al, 2017; Chen et al, 2020), heart ischemia (Cohen et al, 2017), and tumor treatment (Huo et al, 2020; Liu et al, 2020; Qiao et al, 2020).

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