Abstract
Purpose:
Lacrimal gland dysfunction is believed to be the single most important factor resulting in aqueous-deficient dry eye. Regeneration of the lacrimal gland using progenitor cells may potentially restore lacrimal gland function and therefore improve the ocular surface health. Previous studies have documented the role of progenitor cells in the repair of murine lacrimal glands. Since rabbit is a promising animal model for further lacrimal gland study (due to better accessibility to its ocular surface), it is important to study whether the progenitor cells also exist in rabbit LGs. The purpose of this study is to investigate the presence of progenitor cells in intact adult rabbit LGs, and if they could be isolated and expand in vitro.
Methods:
Frozen intact rabbit LG sections were made. While acinar and duct cells were identified by their respective cellular morphology, myoepithelial cells were identified by immunohistochemistry (IHC) using antibody against alpha-smooth muscle actin (α-SMA). The presence of progenitor cells was determined using IHC by exploring for the expression of selected stem cell markers - △Np63, ABCG2, Pax6, vimentin. Immature cells were isolated from LGs using enzyme digestion and mechanical separation and subsequently grown in keratinocyte growth medium (KGM) without fetal bovine serum. The expression of selected stem cell markers and α-SMA in immature cells from passage 0 (P0) to passage 2 (P2) was examined by immunocytochemistry (ICC).
Results:
In the intact adult rabbit LGs, some myoepithlial and duct cells expressed stem cell markers - △Np63, ABCG2, Pax6 and vimentin. Isolated immature cells were found to successfully passage and expand in serum-free KGM, and express stem cell markers - △Np63, ABCG2, Pax6 and vimentin - in a subpopulation from P0 to P2. In addition, some isolated immature cells expressing stem cell markers were also found to be labeled with α-SMA.
Conclusions:
We conclude that progenitor cells exist in intact adult rabbit LGs and can be isolated in vitro. Our results also indicate that the progenitor cells may not only be myoepithelial cells but also duct cells.
Keywords: 576 lacrimal gland •
486 cornea: tears/tear film/dry eye