Blood sample processing for the study of aging, and characterization of caspasemRNA expression in peripheral blood mononuclear cells.

摘要

Centenarian population studies are one of several approaches currently used to study the aging process and characterize successful aging. I have described a methodology permitting the simultaneous generation of RNA, DNA, protein, and plasma samples, as well as fixed peripheral blood mononuclear cells (PBMC) and frozen blood aliquots, from a single 10- to 30-ml sample of peripheral blood obtained from donors of any age, and showed that although extremely old individuals are somewhat anemic, it is possible to obtain enough biological material from their blood to conduct aging studies.; I investigated the possibility of immortalizing B-lymphocytes from extremely old individuals, using the Epstein-Barr virus (EBV), and found that although extremely old individuals (90+ years) possess low levels of circulating B-lymphocytes, it is possible to immortalize B cells present in less than one milliliter of their blood using EBV.; Using biological material obtained from blood samples of individuals of all ages by the method for blood sample processing I have described, I studied the mRNA expression of cell death (specifically caspase) genes in nonagenarians and centenarians, successful models of aging who have survived or avoided age-associated diseases, as well as in their younger counterparts, to determine whether apoptotic genes may be part of the genetic determinants of longevity. I found that a population of extremely old individuals (90+) shows a unique pattern of caspase mRNA expression, characterized by high levels of caspase-1 and -3, and low levels of caspase-8, mRNA, while slightly less aged individuals (70--89) are characterized by high levels of caspase-8 mRNA expression. Furthermore, I showed that these changes in caspase mRNA do not appear to result from age-related changes in PBMC composition, such as decreases in CD24. Therefore, I suggest that unique patterns of caspase mRNA result from the regulation of message abundance on a per cell basis, via a putative regulation of caspase genes at the transcription or RNA processing level, rather than age-associated changes in immune profiles.