Efficacy of mesenchymal stem cell therapy in repairing the structure and the ultrastructure of the rat lacrimal gland after chronic exposure to formaldehyde.

Background: Prolonged exposure to formalin causes chronic lacrimal gland (LG) inflammation, causing dry eye disease. Stem cell therapy may offer more long-lasting and sustainable treatments. The aim of the current research was to examine the therapeutic efficiency of bone marrow mesenchymal stem cells (MB-MSCs) in repairing LG formaldehyde-induced injury in adult albino rats. Methods: The animals were distributed into three groups; control group, lacrimal gland defect, and BM-MSCs-treated group (group I, II, and III, respectively), each containing ten rats. Lacrimal gland injury was induced in groups II and III by chronic exposure to formaldehyde vapor daily for three weeks, group III rats were treated by a single IV dose of BM-MSCs. The histopathology and ultrastructure of the lacrimal gland and its cell's expression of NF-kb were assessed. Relative glandular fibrosis and glandular index were evaluated by morphometric analysis. Culture of the isolated acinar cell and measuring major tears' protein (scIgA, lactoferrin, and lysozyme) in their conditioned media was performed for functional assessment. Results: massive Structural and ultrastructural alteration was recognized in group II along with a significant decrease in the major tear proteins in this group's acinar cell-conditioned media. Most of the acini in group III regained their normal shape and almost their ultrastructure. The glandular index, the relative glandular fibrosis, and the expression of NF-κB almost reached the control levels. The secretory function of acinar cells was significantly improved. Conclusion: BM-MSCs could restore the structure, ultrastructure, and function of LG and may be used as an effective therapeutic approach for dry eye treatment after formalin exposure.