Evaluation of the role of heparinoids as immune modulators of organ perfusion solutions

Kidney transplantation is the only therapy for patients with end-stage kidney failure. There is a shortage of suitable organs from living donors and heart-beating donors (HBDs) leading to an increased use of marginal organs, including those from non- heart-beating donors (NHBD) to expand the donor pool. However, such kidneys are exposed to periods of warm and cold ischaemia plus reperfusion (IR) injury which can be associated with acute tubular necrosis leading to primary non function (PNF), delayed graft failure (DGF) with an increased risk of acute and chronic allograft rejection. Therefore, minimising ischaemic injury will be beneficial to improve immediate allograft function and reduce the incidence of PNF and DGF. Perfusate solutions can ameliorate the damage caused by IR injury. This study examined the possible protective effect of heparinoids, low molecular weight (LMW) sodium heparin (HS-3400) and sodium pentosan polysulfate (NaP PS), as supplements in perfusate solutions. An in vivo rodent surgical model of NHB kidney donation was used to investigate the effects of heparinoids as immune modulators during kidney preservation. It was demonstrated that heparinoids significantly reduced oedema but did not have any effects on pressure, intra-renal vascular resistance (I RVR) or osmolarity of the perfusate solution. Microarray and qPCR analysis revealed that many genes involved in IR injury were differentially expressed after warm oxygenated perfusion. Network analysis revealed that the pro-inflammatory cytokine TNF-a was the common denominator and a potential key regulator of IR injury. Data obtained strongly demonstrate that these networks were removed by the addition of heparinoids. In vitro biological assays investigated the effects of heparinoids on class 11 MHC antigen expression on primary endothelial cells (ECs) treated with IFN-y. It was found that NaPPS and the majority of its derivatives were more efficient in antagonising IFN-y activity. In addition, NaPPS and its derivatives significantly inhibited transendothelial migration of leukocytes across an IFN-y-activated endothelial monolayer. The anti-inflammatory properties of heparinoids can be exploited for better preservation of NHBD organs to improve short and long-term allograft survival and function. Significantly, this is the first study to reveal the potential of heparinoids as TNF-a antagonists and additives to perfusate solutions.EThOS - Electronic Theses Online ServiceGBUnited Kingdo