Abstract
Purpose: :
To identify progenitor cells in the lacrimal gland.
Methods: :
Rat lacrimal glands were dissociated by repetitive cycles of digestion in Type I collagenase. Liberated cells were first grown in serum-supplemented RPMI-1640 medium. To examine plasticity of precursor cells, they were cultured in either serum-free RPMI medium or in X-Vivo medium containing various growth factors. Characterization medium consisted of either RPMI or X-Vivo medium supplemented with 10% FBS. Cells were evaluated for expression of the progenitor cell marker, nestin; the proliferation markerKi-67; the myoepithelial cell markers smooth muscle actin, α-actinin, vimentin, and adenyl cyclase II; the neuronal markers NF-200 and MAP 5; and the glial cell marker, GFAP. Tissue sections of lacrimal gland were also examined for the presence of nestin.
Results: :
Following digestion with collagenase, a variety of cells immediately attached to the culture vessel and became confluent. Gradually, clusters of round immature cells that were nestin and Ki-67 positive began to form and overgrew the underlying monolayer. In FBS-supplemented RPMI medium these cells differentiated into myoepithelial cells expressing smooth muscle actin, α-actinin, vimentin and adenyl cyclase II. When tissue sections of lacrimal gland were evaluated for nestin expression, nestin was observed in a population of myoepithelial cells surrounding both acini and ducts. In separate experiments to examine plasticity of these immature precursor cells, they were grown in X-Vivo neural cell medium that caused them to differentiate into neuronal-like cells, which expressed NF-200 and MAP-5, but not the glial cell marker GFAP.
Conclusions: :
Lacrimal gland myoepithelial cells appear to originate from progenitor cells within the gland and may retain some progenitor cell functions.
Keywords: lacrimal gland • cornea: tears/tear film/dry eye