Stem cell research & therapy 2018 03 229(1) 74 doi 10.1186/s13287-018-0829-x
Three-dimensional (3D) cultures recapitulate the microenvironment of tissue-resident stem cells and enable them to modulate their properties. We determined whether salivary gland-resident stem cells (SGSCs) are primed by a 3D spheroid culture prior to treating irradiation-induced salivary hypofunction using in-vitro coculture and in-vivo transplant models.
3D spheroid-derived SGSCs (SGSCs) were obtained from 3D culture in microwells consisting of a nanofiber bottom and cell-repellent hydrogel walls, and were examined for salivary stem or epithelial gene/protein expression, differentiation potential, and paracrine secretory function compared with monolayer-cultured SGSCs (SGSCs) in vitro and in vivo.
SGSCsexpressed increased salivary stem cell markers (LGR5 and THY1) and pluripotency markers (POU5F1 and NANOG) compared with SGSCs. Also, SGSCsexhibited enhanced potential to differentiate into salivary epithelial cells upon differentiation induction and increased paracrine secretion as compared to SGSCs. Wnt signaling was activated by 3D spheroid formation in the microwells and suppression of the Wnt/β-catenin pathway led to reduced stemness of SGSCs. Enhanced radioprotective properties of SGSCsagainst radiation-induced salivary hypofunction was confirmed by an organotypic 3D coculture and in-vivo transplantation experiments.
The 3D spheroid culture of SGSCs in nanofibrous microwells promotes stem cell properties via activation of Wnt signaling. This may contribute to SGSC priming prior to regenerative therapy to restore salivary hypofunction after radiotherapy.