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The effect of growth factors on the proliferation and differentiation of human nasal gland cells.

OBJECTIVE
To elucidate a mechanism of proliferation and differentiation of nasal gland cells, we established a serum-free 3-dimensional culture system for human nasal gland (HNG) cells and examined the effects of epidermal growth factor, keratinocyte growth factor, and retinoic acid on proliferation and differentiation of cultured HNG cells.


MATERIALS AND METHODS
Nasal polyps were obtained from patients undergoing endoscopic endonasal sinus surgery. The HNG cells were cultured under a monolayer culture and transferred to a collagen-embedded culture using RPMI 1640 medium containing transferrin, insulin, hydrocortisone, retinoic acid, epidermal growth factor, and keratinocyte growth factor. Cell growth was measured by bromodeoxyuridine incorporation assays. To measure cell differentiation, the percentage of cells containing secretory granules, which were stained with Alcian blue in cytoplasm, was determined.


RESULTS
In the serum-free 3-dimensional culture, the HNG cells showed ductal structures containing secretory products in a lumen. The addition of epidermal growth factor promoted the proliferation of HNG cells in its optimal concentrations, and keratinocyte growth factor also enhanced the proliferation of HNG cells. Conversely, the differentiation of HNG cells was not dependent on epidermal growth factor and keratinocyte growth factor. Retinoic acid suppressed the proliferation, but promoted the differentiation of HNG cells.


CONCLUSION
Our culture system could be useful for studying the effects of various growth factors and cytokines on HNG proliferation and differentiation to better understand the mechanisms of growth and morphogenesis of nasal glands.