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Samantha You, Ayesha Tariq, Claire Kublin, Driss Zoukhri; Identification Of Label-retaining Cells And Their Role In Lacrimal Gland Repair Following Experimentally Induced Injury. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5156.
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© ARVO (1962-2015); The Authors (2016-present)
It was previously reported that expression of nestin (a marker of stem cells) increased after experimentally induced injury. Literature shows that stem cells are also label-retaining cells. The purpose of the present studies was to identify and determine the role of label-retaining stem cells during lacrimal gland repair using bromodeoxyuridine (BrdU).
For seven days, female BALB/c mice pulsed with BrdU administered by intraperitoneal injection (1 mg in 0.3 mL). For labeling of noninjured glands, animals were sacrificed at 2, 4, 7, and 12 weeks after pulsing. Lacrimal glands were excised and processed for immunohistochemistry. For labeling of tissue during regeneration, injury was induced in the 12-week chase group by direct injection of recombinant human interleukin-1 (IL-1)α (1 µg in 2 µl) into the exorbital lacrimal glands of anesthetized female BALB/c mice. Animals were sacrificed 3 days after IL-1 injection and glands were removed for histopathology, immunohistochemistry and explant tissue culture. Tissue was directly explanted onto 2-well chamber slides and also cells passaged once were grown on 8-well chamber slides. Cultured cells were maintained in complete Dulbecco’s Modified Eagle Medium (DMEM) supplemented with 10% fetal bovine serum (FBS).
Label retaining cells were observed in lacrimal glands at all time points. The cells were randomly distributed throughout the gland. The number of BrdU+ cells decreased as the chase period increased. By 12 weeks, very few BrdU+ cells can be seen per section. When the lacrimal gland was injured, the number of BrdU cells increased in the area of injury suggesting that the label-retaining cells in the lacrimal gland proliferated after the injury. Immunohistochemistry studies showed that BrdU+ cells were also present in cultures made from tissue explants. Double-labeling experiments revealed that some BrdU staining colocalized with that of nestin, vimentin and α-smooth muscle actin, markers of mesenchymal stem cells in the lacrimal gland.
We concluded from these studies that label-retaining cells are normally present in the lacrimal gland and that their number increased after experimentally induced injury.
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