An In Vitro Culture System for Long-Term Expansion of Epithelial and Mesenchymal Salivary Gland Cells: Role of TGF-β1 in Salivary Gland Epithelial and Mesenchymal Differentiation

Abstract EN

Despite a pivotal role in salivary gland development, homeostasis, and disease, the role of salivary gland mesenchyme is not well understood.

In this study, we used the Col1a1-GFP mouse model to characterize the salivary gland mesenchyme in vitro and in vivo.

The Col1a1-GFP transgene was exclusively expressed in the salivary gland mesenchyme.

Ex vivo culture of mixed salivary gland cells in DMEM plus serum medium allowed long-term expansion of salivary gland epithelial and mesenchymal cells.

The role of TGF-β1 in salivary gland development and disease is complex.

Therefore, we used this in vitro culture system to study the effects of TGF-β1 on salivary gland cell differentiation.

TGF-β1 induced the expression of collagen, and inhibited the formation of acini-like structures in close proximity to mesenchymal cells, which adapted a fibroblastic phenotype.

In contrast, TGF-βR1 inhibition increased acini genes and fibroblast growth factors (Fgf-7 and Fgf-10), decreased collagen and induced formation of larger, mature acini-like structures.

Thus, inhibition of TGF-β signaling may be beneficial for salivary gland differentiation; however, due to differential effects of TGF-β1 in salivary gland epithelial versus mesenchymal cells, selective inhibition is desirable.

In conclusion, this mixed salivary gland cell culture system can be used to study epithelial-mesenchymal interactions and the effects of differentiating inducers and inhibitors.