Fig. 2. Hypothetical link between pre-established endothelial cell injury and endothelial vulnerability with mortality after alloSCT.

Conditioning therapy, immunosuppressive drugs, and post-transplant complications increase endothelial cell distress. In most patients, the threshold to substantial endothelial dysfunction, disturbed microcirculation/microangiopathy and death will not be trespassed (patient 1). Patient 2 with pre-established endothelial cell injury responds similarly to the additional endothelial strains in the context of alloSCT. However, the threshold will be reached due to a lower area of resilience. Patient 3 without pre-established endothelial injury responds more vigorously to the same endothelial challenges due to a patient-specific endothelial vulnerability. The net effect is again an infringement of the threshold and severe complications/death.