Regeneration of Lacrimal Gland Function to Maintain the Health of the Ocular Surface.

Dry eye is a multifactorial disease that is one of the most common diseases worldwide. A major cause of dry eye is the deficiency of aqueous tears, which are mainly secreted from the lacrimal gland. The lacrimal gland plays an important role in maintaining the health of the ocular surface and protecting it from environmental exposure. Dry eye can lead to ocular irritation and discomfort, as well as severe ocular surface diseases (e.g., ocular infections, corneal ulcerations, and ocular surface keratinization). These severe diseases can be induced by an atrophied or injured lacrimal gland; current therapies cannot completely restore the function of lacrimal gland. To develop more definitive therapies, it is important to understand lacrimal gland biology at the molecular level, as well as inflammatory processes affecting the function of the gland. During severe inflammation, the tissue structure of the lacrimal gland is destroyed; it is replaced by scar formation during wound healing, which leads to lacrimal gland dysfunction. Using an animal model of lacrimal gland dysfunction, many investigators have studied molecular mechanisms of inflammation in the lacrimal gland. To restore lacrimal gland function, the lacrimal acini must be restored in their niche. Notably, organ transplantation therapies have been reported to restore lacrimal gland function, directly or indirectly, in animal models. In this review, we describe the current understanding of the lacrimal gland as the therapeutic target for dry eye diseases, as well as recent advances in the field of lacrimal gland cell-based therapy to treat severe dry eye diseases.