Increased expression of angiogenic cytokines in CD56+ uterine natural killer cells from women with recurrent miscarriage.

OBJECTIVE: To compare the expression pattern of angiogenic cytokines in CD56+ uNK cells from peri-implantation endometrium in women with a history of recurrent miscarriage and fertile controls.

METHODS: 28 women were recruited, from which 18 women were diagnosed as recurrent miscarriage and 10 women were of proven fertility. Endometrial biopsy samples were obtained precisely 7 days after luteinization hormone surge in a natural cycle. The angiogenic profile of isolated CD56+ uNK cells was determined by RayBio human angiogenesis antibody array G Series 1000. Differentially expressed angiogenic cytokines between groups were validated by ELISA kits.

RESULTS: CD56+ uNK cells freshly isolated from peri-implantation endometrium were determined to be >90% pure. Angiogenic cytokine array demonstrated that CD56+ uNK cells are one of the angiogenic factors producers in endometrium around the time of embryo implantation. A differential angiogenic cytokine expression profile was found between two groups, with significantly higher expressions of angiogenin, VEGF-A and bFGF in CD56+ uNK cells from women with recurrent miscarriage, compared with fertile controls.

CONCLUSIONS: Differential angiogenic cytokine profile of isolated CD56+ uNK cells suggested the role of uNK cells in the altered endometrial vascularity at the time of implantation, which may account for the endometrial contribution to recurrent miscarriage.