$$\rightleftharpoonup{xx}$$
$$\longleftharp{xx}$$,
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There is a considerable amount of interest in studying fallopian tube epithelium as fallopian tubes play a significant role in reproduction and are the site of origin for most HGSOC. To that end, many investigators have described protocols to isolate fallopian tube cells in both human and mouse models10,11,12,15,16,17,18,19,20,21. The method we describe to extract and enrich for fallopian tube epithelial cells adds to existing fallopian tube cell isolation protocols. Although overlaps exist within these protocols, there are two general types of methods reported in mice and humans. The first involves mincing and enzymatically digesting the whole fallopian tube that gives a total cell suspension10,12,15,16,17. The second involves sloughing with agitation or scraping, which results in sheets of tissue11,18,19,20,21. Both methods allow epithelial cells to be analyzed via downstream experiments such as flow cytometry, sequencing, and in-vitro culture. A major advantage of our method is that the protocol yields a population of fallopian tube cells that are already enriched for epithelial cells through enzymatic digestion and mechanical pushing steps. This population enriched for epithelia can be further digested resulting in a single-cell suspension that can be used for many applications such as flow cytometry, 2D culture, immunocytochemistry, and single-cell RNA sequencing.
Key steps we found to impact cell yield include the duration for which the fallopian tube fragments incubate in 1% trypsin/HBSS and DMEM/DNase. Overincubation in either solution will degrade the cells and significantly decrease the viability of the cells. However, insufficient incubation time will inhibit the researcher's ability to push out many epithelial cells during protocol step 2.6 as they will continue to adhere to each other. It is also important to use a 1% trypsin solution, as both lower and higher concentrations of trypsin solutions reduced the yield of viable fallopian tube epithelial cells. By combining chemical and mechanical isolation and a digestion step (protocol step 3.1), we can exponentially shorten the period it takes to go from tissue to single-cell suspension. This ensures good viability and time to perform downstream analysis on the same day.
In protocol step 1.4, it is critical to ensure that the pieces of fallopian tube cut are 3-5 mm thick. If the pieces are too large, it will be difficult to perform protocol step 2.7 and ultimately decrease the cell yield as a longer incubation time in DMEM/DNase will be necessary.
Although the cell suspension is enriched for epithelial cells, stromal cell contamination is inevitable. If the preparation needs to be purely epithelial cells, sorting using flow cytometry and the markers we described can be performed to isolate epithelial cells and deplete stromal cells.
Postmenopausal fallopian tubes were used in this study. However, this method has been successfully utilized in our lab on premenopausal fallopian tubes. The main difference between pre- and postmenopausal fallopian tubes is the composition of ciliated and secretory epithelial cells1. This protocol works for all reproductive stages.
This efficient protocol will facilitate investigating cell types of the fallopian tube epithelium, including delineating cellular lineages, their dynamic changes during reproductive cycles as well as after menopause, and their role in initiating high-grade serous ovarian cancer.