TABLE 1.
Cell sources in background reference literature.
| Author | Year | Experiment/key findings | Cell source |
|---|---|---|---|
| King et al. (24) | 1989 | Increase in uNK cells during the secretory phase of menstrual cycle | Endometrium from routine hysterectomies |
| Bulmer et al. (39) | 1991 | Increase in uNK cells seen in late secretory endometrium and is sustained through the first trimester | 8–10-week decidua, hysterectomy specimens |
| Flynn et al. (38) | 2000 | Increase in uNK cells during the secretory phase of menstrual cycle | Hysterectomy specimens and EMB at time of tubal ligation |
| Sentman (55) | 2004 | Estradiol and progesterone promotion of chemokine expression to attract peripheral blood NK cells to the endometrium | Hysterectomy specimens (included women on hormone therapy and postmenopausally, 46 ± 11 years)–> created uNK clones |
| Hannan et al. (42) | 2004 | Progesterone-dependent chemotactic recruitment of leukocytes by endometrial cells | Endometrial biopsies from normal, fertile women |
| Jones et al. (43) | 2004 | Chemokines capable of leukocyte recruitment are expressed by epithelial and stromal endometrial cells and upregulated during the implantation window | Endometrial tissue obtained by dilation and curettage from women undergoing gynecological surgical procedures |
| Taylor et al (47) | 2004 | Donor HLA-type leukocytes found after bone marrow transplant suggesting in situ origin of uNK cells | Endometrial biopsies |
| Matsura-Sawada (49) | 2005 | Transplantation of human endometrium into mice lacking NK cells showed an increase in uNK cells | Hysterectomy samples from women with benign gynecologic disease |
| Ordi et al (40) | 2006 | Increase in uNK cells in decidual endometrium independent of the presence of an embryo | EMB from ectopic pregnancy patients |
| Lash et al. (61) | 2006 | Production of angiogenic factors by uNK cells differs by gestational age | 8–10-week decidua, 12–14-week decidua |
| Keskin et al. (45) | 2007 | Exposure of peripheral NK cells to stromal cell conditioned media leads to uNK cell-surface marker expression | 6–12-week decidua |
| Manaster (35) | 2008 | Secretory-phase NK cells are 30% of endometrial lymphocytes vs. 5%–15% of peripheral blood lymphocytes; have a unique receptor repertoire and are cytotoxic and produce cytokines only after IL-15 stimulation | Proliferative- and secretory-phase endometrium |
| Vacca et al (51) | 2011 | Hematopoietic precursors identified that differentiated into cells with uNK cell-surface marker phenotype after coculture with stromal cells | 9–12-week decidua |
| Robson et al. (62) | 2012 | Gestational age-dependent functions of uNK cells | 8–10-week decidua, 12–14-week decidua |
| Szereday et al. (52) | 2012 | Hematopoietic progenitor phenotype cells found in decidual tissue that were dysregulated in women with early spontaneous abortions | 7–12-week decidua |
| Cerdeira et al. (46) | 2013 | Exposure of peripheral NK cells to cocktail of factors converts them to uNK cell phenotype | First trimester decidua |
| Fu (60) | 2017 | “Growth factor-producing” NK cell subset identified that produces factors critical for fetal development | Decidua from elective pregnancy terminations |
| Vento-Tormo et al. (56) | 2018 | Three distinct subpopulations of uNK cells | First trimester decidua (6–14 weeks) |
| Gamliel et al. (59) | 2018 | Existence of “pregnancy trained” uNK cells in repeated pregnancies capable of producing increased levels of interferon gamma and VEGF-alpha, precursors found in endometrium | 6–14-week decidua |
| Suryawanshi et al. (57) | 2018 | Single-cell RNA sequencing indicates “resting” and “proliferative” uNK cell subsets | First trimester decidua |
| Huhn et al. (58) | 2020 | Mass cytometry confirmation of dNK1, dNK2, and dNK3 subsets and chemokine production differences indicating potential functional heterogeneity | 7–12-week decidua |
Note: EMB = endometrial biopsy; HLA = human leukocyte antigen; IL = interleukin; uNK = uterine natural killer; VEGF = vascular endothelial growth factor.