Poster Presentation The 13th International Congress of the Immunology of Diabetes Society 2013

On the road to unraveling the mechanistic pathways of the Instant Blood Mediated Inflammatory Reaction against Porcine Neonatal Islet Cells. (#158)

David Liuwantara 1 , Emmanuel Favaloro 2 , Peta Phillips 1 , Evelyn Salvaris 3 , Joanne Hawkes 1 , Andrew Lew 4 , Mark Nottle 5 , Tony d'Apice 3 , Peter Cowan 3 , Philip O'Connell 1 6 , Wayne J Hawthorne 1 6
  1. CTRR, Westmead Millennium Institute, Westmead , NSW, Australia
  2. Westmead Hospital, Westmead, NSW, Australia
  3. Immunology, St Vincents Hospital, Melbourne, VIC, Australia
  4. Walter and Eliza Hall Institute, Melbourne, VIC, Australia
  5. University of Adelaide, Adelaide, SA, Australia
  6. University of Sydney, Westmead Hospital, Westmead, NSW, Australia

In the immediate post-transplant period following xenotransplantation of porcine neonatal islet cell cluster (NICC) a large number are destroyed due to the Instant Blood Mediated Inflammatory Reaction (IBMIR). It is the initial barrier to the survival of NICC is this rapid activation and binding of platelets to the transplanted NICC, along with the activation of the complement and the coagulation cascades, which can cause a large proportion of the islet cell loss.

The aim of this study was to decipher the mechanistic pathways of IBMIR and to investigate potential methods to reduce or prevent IBMIR from being triggered.

Methods: Our study examined NICC from Gal KO/CD55-CD59-HT+/- pigs, Westran pigs, and these were compared to normal Wild Type (WT) outbred pig NICC. NICC were incubated with freshly collected human blood plasma. Thrombin was measured by an automated thrombin generation assay and complement activation was measured by using cytometric beads assay.

Results: We found that WT NICC triggered large amounts of complement and thrombin. However, Gal KO/CD55-CD59-HT+/- NICC have a reduced thrombin production (AUC at 250 IEQ: 3851 ± 283.7 vs. 5149 ± 490.6 nM*min p<0.001) compared to WT controls. Whereas Westran NICC have delayed lag phase (250 IEQ: 5.8 vs. 3.9 min p<0.05) and delayed peak time (250 IEQ: 12.1 vs. 9.3 min p<0.05) but the AUC for thrombin production was unchanged compared to WT control. We also found that Gal KO/CD55-CD59-HT+/- NICC have reduced complement activation when compared to Westran or WT Control NICC (1.38-fold ± 0.88 vs. 4.45-fold ± 1.2vs 8.15-fold ± 4.48).

Conclusion: Our findings show that CD55/59 expression on gal-KO NICC could reduce IBMIR by inhibiting complement activation and thrombin production, whereas Westran NICC has the ability to delay thrombin generation. A combination of these features could be beneficial in tissues used for xenotransplantation.