Nucleus pulposus (NP) cell senescence is involved in disc degeneration. The in situ osmolarity within the NP region is an important regulator of disc cell’s biology. However, its effects on NP cell senescence remain unclear. The present study was aimed to investigate the effects and mechanism of hyper-osmolarity on NP cell senescence. Rat NP cells were cultured in the in situ -osmolarity medium and hyper-osmolarity medium. The reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) was added along with the medium to investigate the role of oxidative injury. Cell cycle, cell proliferation, senescence associated β-galactosidase (SA-β-Gal) activity, telomerase activity, expression of senescence markers (p16 and p53) and matrix molecules (aggrecan and collagen II) were tested to assess NP cell senescence. Compared with the in situ -osmolarity culture, hyper-osmolarity culture significantly decreased cell proliferation and telomerase activity, increased SA-β-Gal activity and cell fraction in the G 0 /G 1 phase, up-regulated expression of senescence markers (p16 and p53) and down-regulated expression of matrix molecules (aggrecan and collagen II), and increased intracellular ROS accumulation. However, addition of NAC partly reversed these effects of hyper-osmolarity culture on cellular senescence and decreased ROS content in NP cells. In conclusion, a hyper-osmolarity culture promotes NP cell senescence through inducing oxidative stress injury. The present study provides new knowledge on NP cell senescence and helps us to better understand the mechanism of disc degeneration.
Missed abortion is one of the common complications of assisted reproductive technology (ART). Genetic abnormality is the most important factor. However, the effect of ART on the molecular karyotype of products of conception (POC) remains unknown. We explored the effect of ART on the molecular karyotype of POC in miscarriage. POC were obtained from women undergoing ART. Single nucleotide polymorphism (SNP) microarray was used to analyze the molecular karyotype. A total of 1493 POC were collected for SNP array analysis. The total rate of karyotypic abnormalities was 63.1% (943/1493). The proportion of karyotypic abnormalities was 70.4% (193/416) in >35-year-old group, which was significantly higher than that (60.6%) (343/566) in <30-year-old group and that (60%) (307/511) in the 30–35-year-old group. In natural conception (NC) group, the proportion of karyotypic abnormalities was 64.6% (201/311), whereas in ART group it was 62.7% (742/1182) and, there was no significant difference. The ratio between male and female fetuses was 1:1.13 (698/795). The rate of karyotypic abnormalities in male was 62.9% (439/698) and that in female was 63.4% (504/795), and these values did not differ significantly ( P =0.84). Molecular karyotypic abnormality is the most important reason in miscarriage, and female age is a significant factor influencing the karyotypic abnormalities. Comparison with NC, ART, and gender of aborted embryos may not increase the rate of molecular karyotypic abnormality in miscarriage.