Low molecular weight dextran sulfate prevents complement activation and delays hyperacute rejection in pig‐to‐human xenotransplantation models

Abstract

Dextran sulfate of 5000 molecular weight (DXS 5000) is known to block complement activation as well as the intrinsic coagulation cascade by potentiation of C inhibitor. The effect of DXS 5000 on hyperacute rejection (HAR) was tested in pig-to-human xenotransplantation models. For in vitro testing, a cytotoxicity assay was used with the pig kidney cell line PK15 as target cells and fresh, undiluted human serum as antibody and complement source. Ex vivo pig lung perfusion was chosen to assess DXS 5000 in a physiologic model. Pig lungs were perfused with fresh, citrate-anticoagulated whole human blood to which 1 or 2 mg/ml DXS 5000 were added; the lungs were ventilated and the blood de-oxygenated. Pulmonary vascular resistance (PVR) and blood oxygenation (deltapO2) were monitored throughout the experiment. Autologous pig blood and human blood without DXS 5000 served as controls. In the PK 15 assay DXS 5000 led to a complete, dose-dependent inhibition of human serum cytotoxicity with an average IC50 of 43 +/- 18 microg/ml (n=8). Pig lungs perfused with untreated human blood (n=2) underwent HAR within 105 +/- 64 min, characterized by increased PVR, decrease of deltapO2, and generalized edema. Microscopically, capillary bleeding as well as deposition of human antibodies, complement and fibrin could be observed. Addition of DXS 5000 (n=4) prolonged lung survival to 170 +/- 14 min for 1 mg/ml and 250 +/- 42 min for 2 mg/ml. and PVR values as well as edema formation were comparable to control lungs that were perfused with autologous pig blood (n=2). Activation of complement (activation products in serum, deposition on lung tissue) and the coagulation system (fibrin monomers) were significantly diminished as compared to human blood without DXS 5000. Binding of anti-Gal antibodies was not influenced, and in vitro experiments showed no evidence of complement depletion by DXS 5000. In conclusion, DXS 5000 is an efficient complement inhibitor in pig-to-human xenotransplantation models and therefore a candidate for complement-inhibitory/anti-inflammatory therapy either alone or in combination with other substances and warrants further investigation.

Curcumin Has Potent Liver Preservation Properties in an Isolated Perfusion Model

“…New organ preservation solutions are formulated to prevent or reduce the aforementioned factors. For example, the use of calcium and potassium channel blockers to prevent K ϩ efflux and Ca ϩϩ influx, thus to reduce the Ca ϩϩ induced ATP depletion in the cells and to prevent cell edema; the use of metallo-proteinase (MMP) inhibitors to prevent MMP, especially MMP-2 induced tissue inflammation (23); the use of complement inhibitors to prevent multimolecular assembly of C5b-9 that is able to damage cell membrane, thus induces cell lysis and organ damage (24,25); the use of heme oxygenases, such as heme oxygenase-1 (HO-1), to down-regulate inflammation (26,27) and the use of N-acetyl cysteine (NAC) to reduce oxidative stress (28).…”

Protection of Endothelial Cells by Dextran Sulfate in Rats with Thrombotic Microangiopathy

“…Complement-mediated EC activation and damage have also been demonstrated in the pathophysiology of acute vascular rejection in xenotransplantation (31). DXS inhibits complement in vitro experiments using human serum and porcine cells (32). Similarly, DXS inhibited complement in vivo by preventing hamster cardiac xenografts from undergoing acute vascular rejection, and DXS in combination with cyclosporin A significantly prolonged xenograft survival rate (33).…”

Multimeric tyrosine sulfate acts as an endothelial cell protectant and prevents complement activation in xenotransplantation models

“…In a previous study, we have demonstrated that the sulfated polyglucose dextran sulfate (DXS) is a very potent complement inhibitor and able to delay HAR in a pig lung perfusion model with human blood [10]. Moreover, we have shown recently that DXS acts as an EC-protectant and prevents human complement-and natural killer (NK) cell-mediated cytotoxicity towards porcine cells in vitro [11].…”