Advances in Functional Restoration of the Lacrimal Glands.

The lacrimal glands produce tears to support a healthy homeostatic environment on the ocular surface. The lacrimal gland dysfunction characteristic of dry eye disease causes ocular discomfort and visual disturbances and in severe cases can result in a loss of vision. The demand for adequate restoration of lacrimal gland function has been intensified due to advances in stem cell biology, developmental biology, and bioengineering technologies. In addition to conventional therapies, including artificial tears, tear alternatives (such as autologous serum eye drops) and salivary gland transplantation, a regenerative medicine approach has been identified as a novel strategy to restore the function of the lacrimal gland. Recent studies have demonstrated the potential of progenitor cell injection therapy to repair the tissue of the lacrimal glands. A current three-dimensional (3D) tissue engineering technique has been shown to regenerate a secretory gland structure by reproducing reciprocal epithelial-mesenchymal interactions during ontogenesis in vitro and in vivo. A novel direct reprogramming method has suggested a possibility to induce markers in the lacrimal gland developmental process from human pluripotent stem cells. The development of this method is supported by advances in our understanding of gene expression and regulatory networks involved in the development and differentiation of the lacrimal glands. Engineering science has proposed a medical device to stimulate tearing and a bio-hybrid scaffold to reconstruct the 3D lacrimal gland structure. In this review, we will summarize recent bioengineering advances in lacrimal gland regeneration toward the functional restoration of the lacrimal glands as a future dry eye therapy.