Altered expression of genes involved in the production and degradation of endometrial extracellular matrix in patients with unexplained infertility and recurrent miscarriages.

During the secretory phase of the menstrual cycle, the composition of extracellular matrix (ECM) in endometrium changes to favour implantation. In the present study, we have analysed whether some cases of unexplained infertility and recurrent abortions could be explained by abnormal production or turnover of endometrial ECM. Comparison of mRNA levels of a panel of collagens, matrix metalloproteinases (MMP), tissue inhibitors of metalloproteinases (TIMP) and cathepsins in the samples revealed higher levels of type I collagen, MMP-2 and cathepsin H and decreased levels of TIMP-3 mRNA in mid-secretory endometrium of patients with unexplained infertility and/or recurrent miscarriages when compared with normal mid-secretory endometrium. Furthermore, changes were also seen in the levels of type I collagen and TIMP-3 mRNA between the proliferative and mid-secretory phases of normal endometrium. The results suggest an altered ECM turnover in the endometrium of patients with fertility disorders prior to implantation.