Splenectomy in zebrafish: a new model for immune thrombocytopenia

In humans, splenectomy is performed to treat many clinical disorders, including immune thrombocytopenia. However, the incidence of splenectomies for immune thrombocytopenia as a therapeutic has significantly declined over the past decade due to the availability of new therapies. Infection and sepsis as a result of splenectomies are well documented, but other long-term effects are not well characterized. Evidence suggests that persons who have had a prior splenectomy may be at an increased risk of vascular conditions. Also, elevated levels of cell-derived microparticles appear to contribute to an increased risk of thrombosis and cardiovascular disease. However, in vivo studies on the increased levels of microparticles following splenectomy are limited. In order to understand the effects of splenectomies, we developed a protocol for splenectomy in adult zebrafish. After anesthesia, the spleen was removed under a stereomicroscope after making an incision on the ventral side of the fish. The spleen was removed by pulling with forceps. The incision was closed by Vetbond tissue glue. Blood collected from both splenectomized zebrafish and those that underwent sham surgeries was immunolabeled with polyclonal antisera against alpha IIb, followed by flow cytometry. We observed elevated levels of thrombocytes and their microparticles in splenectomized zebrafish. Finally, by injecting alpha IIb antibody intravenously into zebrafish, we found the thrombocyte counts decreased, suggesting the fish developed immune thrombocytopenia like conditions, which were then reversed by splenectomy. In summary, the model developed here should be useful to study molecular changes due to splenectomy. Also, the zebrafish will be useful in modeling treatment of immune thrombocytopenia like conditions.