In-vitro reconstitution of three-dimensional human salivary gland tissue structures

This study aimed to achieve functional reconstitution of salivary units from human salivary gland cells in an in vitro three-dimensional culture system. Human salivary cells were isolated from human salivary gland tissue, cultured, expanded, and placed into a three-dimensional culture system containing collagen and matrigel. Morphogenesis of reconstituted salivary structures was assessed by histomorphometry and transmission electron microscopy. Phenotypic and functional characteristics were assessed by immunohistochemistry and reverse transcription polymerase chain reaction (occludin, claudin 1, ZO-1, aquaporin 5, amylase) as well as spectrophotometric biochemical assay to measure amylase production. In a novel gel culture system, single human salivary cells divided and assembled into three-dimensional acinar and ductal structures in the presence of collagen and matrigel. All salivary gland units produced amylase and expressed aquaporin-5, a critical water channel protein. Tight junction proteins ZO-1, occludin, and claudin-1 were expressed under all culture conditions. Electron microscopy demonstrated desmosomes, microvilli, and secretory granules. This study showed that functional, differentiated salivary units containing acini and ducts formed from single salivary cells in a three-dimensional culture system. This in vitro culture system could be used to engineer functional salivary tissue in vivo.