麦克维尔长沙总代理:Telomerase expression in fertile patients com...
A. C. Lorch, A. Franco, J. C. McSweet, D. L. Keefe, H. J. Kliman; Yale University, New Haven, CT, Brown University, Providence, RI
Objective: A very thin endometrial lining that is unresponsive to estrogen is often associated with infertility and failed ART cycles. We hypothesized that these patients may have a decrease or absence of endometrial epithelial stem cells compared to normal patients. Telomerase defines immortalized stem cells and is present in tissues that continually regenerate, including the endometrium. We first identified the pattern of telomerase expression in endometrial glands across the menstrual and mitotic cycles in fertile normal controls and then compared this to telomerase expression in cases of unresponsive, thin endometria.
Design: Endometrial biopsies from both the follicular and the luteal phases of the menstrual cycle in normal fertile women and women with thin endometria were immunohistochemically stained for telomerase and quantitatively assessed for pattern and percent of glandular nuclei stained.
Materials and Methods: Cycle day 15 (n=4) and day 24 (n=5) endometrial biopsies from parous Endometrial Function Test (EFT?) normal (Fertil Steril 80:146-56, 2003) or thin endometrial patients (d15 = 4, d24 = 8) were stained with mouse anti-human telomerase antibody (Vector Laboratories, Burlingame, CA). Percent of glandular nuclei and cytoplasm stained, as well as the patterns of staining, were compared between the two groups. Liver, heart and lung were used as negative controls.
Results: Telomerase appeared in two patterns in normal endometrial glands: punctate and diffuse. Smaller, presumably G0 and G1, resting cells exhibited only a punctate nuclear pattern (Figure, arrow heads). Cells with visible chromatin condensation (prophase) exhibited both punctate and diffuse patterns in the nuclei. Larger cells with visible mitotic figures (metaphase) exhibited a diffuse pattern, with telomerase dispersed throughout the entire cell (Figure, arrow). Mitotic figures were frequent in the normal day 15 biopsies but absent in the day 24 biopsies. The average percentage of normal glands stained with telomerase was 94.5% on day 15 and 60% on day 24 with the diffuse pattern being present in 5.5% of nuclei on day 15 and no nuclei on day 24. The thin endometria had fewer mitotic figures on day 15, less telomerase staining on day 15 (85%) and day 24 (56%), and only 1.4% of the nuclei had diffuse staining on day 15 compared to normal patients. No telomerase was observed in liver, heart or lung samples.
Conclusion: Telomerase is present in high concentrations in endometrial glandular cells, consistent with their stem cell nature. In G0 and G1 resting phase cells, telomerase is stored in punctate nuclear particles. As the glandular epithelial cells move into the S, G2 and M phases of the mitotic cycle the telomerase appears to be released from its storage depots where it presumably associates with and rejuvenates the telomeres of the replicating DNA. Following anaphase the telomerase is apparently degraded, but reappears in its punctate storage form as the cells reenter G0 or G1. Samples from thin endometria have less, but not absent, telomerase, suggesting that decreased telomerase may partly explain this clinical condition.
Support: Reproductive and Placental Research Unit, Yale University
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Last modified 10.21.04