Figure 5. Immunohistological expression of representative genes in transplanted porcine renal and cardiac xenografts.

Selected immunohistological confirmation of the tabulated gene microarray studies (Table 2) demonstrating upregulation of von Willebrand factor (vWF) in porcine kidneys (A) and hearts (B) transplanted into baboons. Heightened P-selectin staining was present in porcine renal xenografts (C) relative to cardiac xenografts (D) prior to rejection, indicating both upregulation of endothelial cell expression as well as heightened platelet sequestration in kidneys, relative to hearts. Renal graft staining for plasminogen activator inhibitor-1 (PAI-1) (E) did not increase in functioning grafts and was comparable to the basal expression in the native kidneys, until fully established rejection was noted, whereas increases of plasminogen activator inhibitor-1 staining were notable in functioning cardiac grafts (F). Heme oxygenase-1 (HO-1) expression was increased in both renal (G) and cardiac (H) xenografts. Heightened CD39 expression was pronounced in renal grafts (I), where it was associated with vWf expression with extensive platelet sequestration. Some increment of CD39 staining was also seen in the cardiac xenografts (J). Expression of this ectoenzyme was lost when rejection became fully established in both kidneys and hearts with extensive tissue destruction (not shown).