Table VI.

Concepts in tissue procurement and preservation

Tissue protein biomarkers: preanalytical procurement validation and guidelines for minimizing preanalytical variables during clinical tissue procurement
1. Tissue procurement protocols must be based on the recognition that the excised tissue is alive and reactive to ex vivo stress. Kinase pathways are active and reactive until the tissue cells are stabilized.
2. Based on time course analysis of phosphoproteins, tissue should be stabilized as soon as possible after excision. Taking into consideration the average time for procurement in a community hospital, the recommended maximum elapsed time is 20 min from excision to stabilization (e.g. flash freezing, thermal denaturation, or chemical stabilization).
3. For preservation of kinase pathway proteins, stabilization methods should be designed to block both sides of the kinase/phosphatase kinetics. Blocking the phosphatases only can cause false elevation of the phosphorylation level of the analyte.
4. Reactive changes occurring in tissue postexcision can generate false elevation as well as false decline in protein (or molecular) analytes. This is a significant source of bias for clinical biomarker qualification and must be known before a tissue biomarker is selected for clinical use.