Transitioning of renal transplant pathology from allograft to xenograft and tissue engineering pathology: Are we prepared?

Table 2 Types of chronic xenograft vasculopathy

Type of vasculopathy	Histopathological features
Chronic humoral rejection-associated vasculopathy	Arterial intimal thickening; Presence of TUNEL+ cells; Deposits of fibrin, immunoglobulins (IgG and IgM), and complement components (C3, C4d, and C5b-9)
Chronic cellular rejection-associated vasculopathy	Mononuclear cell infiltration in the neointima; Active endothelialitis; TUNEL+ cells
Combined chronic humoral and cellular rejection-associated vasculopathy	Fibrinoid material deposition and cellular infiltration in the arterial neointima with immunoglobulin and complement deposition and infiltration of T cells, macrophages, and polymorphonuclear leukocytes
Fully developed vasculopathy	Narrowing of arteries with a fibrotic neointima, but without fibrinoid material, or cellular infiltration

TUNEL: Terminal deoxynucleotidyl transferase dUTP nick end labeling.