Tissue engineering of human salivary gland organoids

Radiation therapy for malignant head and neck tumours is mainly responsible for inadvertent damage of the salivary glands. Xerostomia is the major symptom of this condition, with consequent mucositis, dental caries, dysphagia and nutritional deficits. At present there is no routine treatment for radiation-induced salivary dysfunction. Based on the principles of tissue engineering, this study presents a new experimental concept for reconstituting salivary gland function after radiation therapy for head and neck cancer. Human parotid cells were cultured with two different types of commercially available microcarriers-Cytodex 3 and Cytopore 1-for up to 3 weeks in vitro. Cultures were controlled daily by means of inverted microscopy. Medium samples were tested for alpha-amylase, tissue polypeptide antigen (TPA) and S100 in order to control parotid cell function in vitro. The vitality of the cells was investigated by in vitro staining with erythrosine. Immunocytochemical analysis for amylase and cytokeratin was performed in order to confirm epithelial character and maintain acinar cell type. Parotid gland cells could be cultured in a differentiated and vital state on both types of microcarriers for up to 3 weeks. Almost all of the cultured cells exhibited immunoreactivity for cytokeratin. High concentrations of TPA, a specific marker for salivary duct epithelium, indicated persistent differentiation of this cell type in vitro. Positivity for amylase was detectable in 20-45%, of cells growing on the microcarriers, and especially on Cytodex 3. Decreasing amylase levels in the culture medium indicated functional deficiencies of the remaining acinar cells. Tissue engineering of human salivary gland organoids on microcarriers is a new approach for potential causative treatment of radiation-induced xerostomia. Before clinical application can be considered significant improvements in the in vitro cultivation of salivary gland tissue and scaffold design have to be realized.