Mouse parotid salivary gland organoids for the in vitro study of stem cell radiation response.

OBJECTIVE Hyposalivation related xerostomia is an irreversible, untreatable and frequent condition after radiotherapy for head and neck cancer. Stem cell therapy is an attractive option of treatment, but demands knowledge of stem cells functioning. Therefore, we aimed to develop a murine parotid gland organoid model to explore radiation response of stem cells in vitro. MATERIAL AND METHODS Single cells derived from murine parotid gland organoids were passaged in Matrigel with defined medium to assess self-renewal and differentiation potential. Single cells were irradiated and plated in a 3D clonogenic stem cell survival assay to assess submandibular and parotid gland radiation response. RESULTS Single cells derived from parotid gland organoids were able to extensively self-renew and differentiate into all major tissue cell types, indicating the presence of potential stem cells. FACS selection for known salivary gland stem cells markers CD24/CD29 did not further enrich for stem cells. The parotid gland organoid derived stem cells displayed radiation dose response curves similar to the submandibular gland. CONCLUSIONS Murine parotid gland organoids harbor stem cells with long term expansion and differentiation potential. This model is useful for mechanistic studies of stem cell radiation response and suggest similar radiosensitivity for the parotid and submandibular gland organoids.