Cadmium induces spontaneous abortion by impairing endometrial stromal cell decidualization.

Cadmium (Cd) is a toxic heavy metal with a high propensity to accumulate within the body, and Cd accumulation has been shown to cause organ damage. However, it is unclear whether Cd accumulation is a cause of impaired decidualization, which induces to spontaneous abortion (SA). In this study, we found that the decidual Cd concentration was increased in patients with SA and positively correlated with the occurrence of SA. The levels of two decidualization markers (prolactin, PRL and insulin-like growth factor binding protein 1, IGFBP1) were reduced in the decidua of all-cause SA patients. Using 8-week ICR female mice, we further established a uterus-specific Cd accumulation mouse model and verified that Cd-accumulating mice had increased numbers of absorbed fetuses and defective decidualization. Finally, using in vitro-cultured human ENdometrial stromal cells (hEnSCs), we found that Cd accumulation significantly inhibited decidualization; and moreover, Cd treatment downregulated the regulatory genes upstream of PRL and IGFBP1 such as PGR, ESR1, ESR2 and FOXO1. This study suggests that Cd accumulation could produce impaired decidualization by downregulating the upstream regulators of PRL and IGFBP1, thereby increasing the risk of SA. Our study offered new possibilities for the prevention and treatment of spontaneous abortion.