BACKGROUND: The placenta is a unique organ that despite constant influences by external factors, has a defined life span of approximately 40 weeks in humans. This is the result of aging, which mitochondria play an important role, however its role of aging in a healthy pregnancy remains elusive. This study aimed to identify aging markers and the role of mitochondria within healthy placentae collected from term and post-term pregnancies.
METHODS: Term (39-40 weeks' gestation, n=6-7) and post-date (41-42 weeks' gestation, n=6-7) human placental samples were taken at delivery from the Gold Coast University Hospital, Queensland. Following RNA extraction, qRT-PCR was utilised to measure genes to assess the profile of cellular stress and dysfunction associated with gestational aging. Subsequent protein extraction and western blotting was performed on proteins of interest. Gene and protein markers of aging and mitochondrial processes were measured via qPCR and western blotting.
RESULTS: This study found increases of senescence marker p53 and anti-apoptotic marker BCL-2 were observed in post-term placenta. Gene expression of SIRT1, SIRT3, FOXO1 and TFAM were decreased in post-term tissue, however, mitochondrial complex I, III, IV and V were increased, possibly due to an observed increase in mitofusins MFN1 and MFN2 protein expression. The increase in citrate synthase/mitochondrial content in post-term placenta is suggestive of an increase in mitochondrial adaptations in healthy post-term placenta.
DISCUSSION: These observed changes in mitochondrial adaptation and aging markers may be the reason why some placental tissue can progress to post-term, whilst others can turn pathological.