Using cell sheets to regenerate mouse submandibular glands.

Temperature-responsive polymer grafted tissue culture dishes release cells as confluent living sheets in response to small changes in temperature, with recovered cell sheets retaining cell-cell communications, functional extracellular matrices and tissue-like behaviors. These features promote tissue regeneration and improve transplantation efficacy in various tissues including cartilage, heart, kidney, liver, endometrium, cornea, middle ear, periodontium, and esophageal living sheet transplants. However, the functional effects of cell sheets for salivary gland regeneration to treat hyposalivation have not yet been studied. Thus, the present study aims to both establish the viability of thermoresponsive cell sheets for use in salivary glands and then explore the delivery option (i.e., single vs. multiple layers) that would result in the most complete tissue growth in terms of cell differentiation and recovered tissue integrity. Results indicate that single cell sheets form polarized structures that maintain cell-cell junctions and secretory granules in vitro while layering of two-single cell sheets forms a glandular-like pattern in vitro. Moreover, double layer cell sheets enhance tissue formation, cell differentiation and saliva secretion in vivo. In contrast, single cell sheets demonstrated only modest gains relative to the robust growth seen with the double layer variety. Together, these data verify the utility of thermoresponsive cell sheets for use in salivary glands and indicates the double layer form to provide the best option in terms of cell differentiation and recovered tissue integrity, thereby offering a potential new therapeutic strategy for treating hyposalivation.