Platelet sequestration and activation during GalTKO.hCD46 pig lung perfusion by human blood is primarily mediated by GPIb, GPIIb/IIIa, and von Willebrand Factor

Abstract

Background Here we ask whether platelet GPIb and GPIIb/IIIa receptors modulate platelet sequestration and activation during GalTKO.hCD46 pig lung xenograft perfusion. Methods GalTKO.hCD46 transgenic pig lungs were perfused with heparinized fresh human blood. Results from perfusions in which αGPIb Fab (6B4, 10mg/L blood, n=6), αGPIIb/IIIa Fab (ReoPro, 3.5mg/L blood, n=6), or both drugs (n=4) were administered to the perfusate were compared to 2 additional groups in which the donor pig received DDAVP, 3μg/kg (to pre-deplete pVWF, the main GPIb ligand), with or without αGPIb (n=6 each). Results Platelet sequestration was significantly delayed in αGPIb, αGPIb+DDAVP and αGPIb+αGPIIb/IIIa groups. Median lung “survival” was significantly longer (>240 vs. 162min reference, p=0.016), and platelet activation (as CD62P and βTG) were significantly inhibited, when pigs were pre-treated with DDAVP, with or without αGPIb Fab treatment. Pulmonary vascular resistance rise was not significantly attenuated in any group, and was associated with residual thromboxane and histamine elaboration. Conclusions The GPIb-VWF and GPIIb/IIIa axes play important roles in platelet sequestration and coagulation cascade activation during GalTKO.hCD46 lung xenograft injury. GPIb blockade significantly reduces platelet activation and delays platelet sequestration in this xenolung rejection model, an effect amplified by adding αGPIIb/IIIa blockade or depletion of VWF from pig lung.

Effects of carbon monoxide on early dysfunction and microangiopathy following GalT‐KO porcine pulmonary xenotransplantation in cynomolgus monkeys

“…In addition, others have reported platelet activation and sequestration become attenuated when desmopressin is administered to pigs prior to lung procurement to deplete pig vWF . Alternatively, Burdorf L et al recently showed the important role of anti‐GPIb Ab therapy on reducing lung xenograft injury that could be a potential additive treatment to inhibit platelet activation.…”

A review of pig liver xenotransplantation: Current problems and recent progress

“…96 GPIb blockade proved insufficient to prevent platelet activation and sequestration in pig livers perfused with human blood, 97 but a combination of GpIb and GpIIb/IIIa blockade successfully prevented platelet sequestration. 98 Pre-infusion of 1-deamino-8-d-arginine vasopressin to the donor pig reduced vWF content in the lung graft to attenuate platelet activation and complement/coagulation activation. 99 α-1-Antitrypsin, a circulating anti-inflammatory glycoprotein, inhibited proteases released by inflammatory cells, especially neutrophils, to attenuate xenograft rejection.…”

“…The fusion protein, GpVI‐CD39, effectively delayed vascular thrombosis without a risk of bleeding . GPIb blockade proved insufficient to prevent platelet activation and sequestration in pig livers perfused with human blood, but a combination of GpIb and GpIIb/IIIa blockade successfully prevented platelet sequestration . Pre‐infusion of 1‐deamino‐8‐d‐arginine vasopressin to the donor pig reduced vWF content in the lung graft to attenuate platelet activation and complement/coagulation activation .…”

Xenotransplantation

“…Burdorf et al showed that platelet sequestration and activation during GTKO.hCD46 pig lung perfusion by human blood was primarily mediated by GPIb, GPIIb/IIIa, and von Willebrand Factor [22]. Laird et al showed that transgenic expression of human leukocyte antigen (HLA)-E attenuates GTKO.hCD46 pig lung xenograft injury [23].…”