Telomerase activity in pregnancy complications (Review)

Telomeres are specific DNA regions positioned at the ends of chromosomes and composed of functional non-coding repeats. Upon cell division, the telomeres decrease in length by a preordained amount. When the telomeres become critically short, cells lose the ability to divide and enter a specific functioning mode designated as 'cellular senescence'. However, human tissues express an enzyme that deters the shrinking of the telomeres, the telomerase. Due to its ability to maintain telomere length, the telomerase slows down and possibly suspends the aging of the cells. In regard to this, solid evidence demonstrates that female human fertility decreases with increased maternal age and that various adverse factors, including alterations in telomerase activity, can contribute to age-associated infertility in women. The fact that telomerase activity is regulated in a time- and location-dependent manner in both embryo and placental tissues, highlights it potential importance to the successful completion of pregnancy. Since maternal age is a crucial determining factor for the success of in vitro and in vivo fertilization, numerous studies have focused on telomerase activity and its correlation with mammalian fertilization, as well as the following cleavage and pre-implantation developmental processes. Associations between telomerase activity and pregnancy complications have been previously observed. Our aim in this review was to summarize and critically discuss evidence correlating telomerase activity with pregnancy complications.