† These authors contributed equally.
We explored the correlation between extracellular matrix (ECM) components and spontaneous abortion by defining the types and levels of ECM proteins that are transcriptionally and translationally expressed in endometrial stromal (ES) cells. The ES cells were retrieved from the uterus of a woman who had experienced normal delivery without spontaneous abortion and one who had experienced spontaneous abortion. In the presence and absence of spontaneous abortion, the transcription of eight ECM protein-encoding genes [fibronectin, nidogen-1, tenascin C, vitronectin, elastin, collagen type 1 alpha 1 chain (COL1A1), COL3A1, and COL5A2] was observed, whereas four ECM protein-encoding genes (laminin, COL2A1, COL4A3, and COL11A1) were not transcribed. Translation of all ECM protein-encoding genes was equally observed on the surface of ES cells derived from women with normal pregnancy and spontaneous abortion; however, the proportion of ES cells expressing each ECM protein and the quantity of each ECM protein expressed on the cell surface were significantly different. These results demonstrate that altered expression of ECM proteins in ES cells constituting the endometrium may be a key factor in triggering spontaneous abortion.