Mitochondrial transformations in the aging human placenta.

Mitochondria play a key role in homeostasis and are central to one of the leading hypotheses of aging, the free radical theory. Mitochondria function as a reticulated network, constantly adapting to the cellular environment through fusion (joining), biogenesis (formation of new mitochondria), and fission (separation). This adaptive response is particularly important in response to oxidative stress, cellular damage, and aging, when mitochondria are selectively removed through mitophagy, a mitochondrial equivalent of autophagy. During this complex process, mitochondria influence surrounding cell biology and organelles through the release of signaling molecules. Given that the human placenta is a unique organ having a transient and somewhat defined life span of ∼280 days, any adaption or dysfunction associated with mitochondrial physiology as a result of aging will have a dramatic impact on the health and function of both the placenta and the fetus. Additionally, a defective placenta during gestation, resulting in reduced fetal growth, has been shown to influence the development of chronic disease in later life. In this review we focus on the mitochondrial adaptions and transformations that accompany gestational length and share similarities with age-related diseases. In addition, we discuss the role of such changes in regulating placental function throughout gestation, the etiology of gestational complications, and the development of chronic diseases later in life.