Tuesday, September 4, 2012
The process of creating formalin fixed paraffin embedded (FFPE) tissue and and fixed, H&E stained slides has been around for over a hundred years. It's a standard tool used by clinicians, pathologists and researchers in many life-science fields. Fixed material is stable at room temperature and can be conveniently stored for long periods. Since these techniques has been around for a while, hospitals and research labs all over the world have tended to accumulate huge archives of fixed material containing many millions of specimens and dating back many decades. In hospitals, this can include tissue removed as biopsies, resected material removed from patients during surgery and samples collected post-mortem. Hospitals keep these samples as a way to keep track of patient histories, monitor long-term changes of a patient's condition, ensure and improve the accuracy of diagnosis of disease and to meet legal record-keeping obligations. Only a tiny proportion of the massive global stockpile of preserved tissue has ever been used for research purposes, and for smaller community hospitals with no research labs on site, we can assume that virtually none of the tissue collected yields any research benefit to anyone once it's clinical purpose has been fulfilled. After a certain amount of time has elapsed, some organizations simply dispose of old samples, or move them to long-term storage facilities, never again to see the light of day. Until recently, the research value of old, preserved tissue specimens seemed dubious anyway, since preserved tissue is biologically inactive and samples are of sufficiently small size as to make the extraction of useful biochemicals impractical using traditional approaches.