Senescence in amniocytes and placentas from trisomy 21 pregnancies

Objective: Senescence has been described as a stable cell proliferation arrest resulting from the progression of primary human fibroblasts through a finite number of population doublings in vitro. Accelerated telomere shortening was observed in pregnancies complicated by intrauterine growth restriction, in placentas of diabetic mothers and trisomy 21 amniocytes. We hypothesized that under conditions of stress, telomeres in placentas will be shorter and there will be more cells with the senescence phenotype. Methods: The two study groups included placental biopsies from 7 cases of trisomy 21 and amniocytes from 10 cases of trisomy 21. The control groups consisted of placental biopsies from 6 cases and amniocytes from 10 pregnancies with a normal karyotype. The samples were analyzed for the presence of senescent cells based on the number of fragments in each cell. Results: A significantly higher percentage of cells in the senescent state, based on a higher percentage of cells with more fragmentations, were found in the amniocytes (20.8%) and in trophoblasts (94.3%) from placentas with trisomy 21 compared to the control groups. Conclusion: Among other genetic instability parameters, trisomy 21 amniocytes and trophoblasts express a higher prevalence of senescent cells than were previously reported.