The enhancement of submandibular gland branch formation on chitosan membranes

Many glandular organs are developed by branching morphogenesis, an efficient and ubiquitous process for creating a larger cellular area for metabolic requirement. To regenerate a glandular organ, such as salivary glands, recapitulation of branching processes may be requisite. At present, the roles of biomaterials in regenerative branching have never been thoroughly explored. By culturing the embryonal submandibular gland (SMG) on different substrata, including polyvinyl alcohol (PVA), chitosan, and polycarbonate (PC), this study demonstrated for the first time that chitosan was capable of providing a more preferential environment for salivary gland branch formation. After culturing SMG explants on chitosan membranes, secreted extracellular matrices distributed in a reticular manner and formed thicker fibers beyond the extents of cell attachment, which were not found in PVA and PC. In the subsequent culture of explants just on the used chitosan substrates, these conditioned membranes were able to further enhance SMG branching. The fact that the promoting effects were eliminated with collagenase treatment and type I and type III collagen were identified within the adherent fibrillar extracellular matrix raised the possibility that the stimulating factors were collagen-originated. This indicates that, for SMG, chitosan is a bioactive substratum which enables cells to synthesize and deposit essential extracellular matrix, paving an important way for ensuing branch formation. Accordingly, the current study provides a larger scope to use chitosan as a biomaterial for recapitulating branching, which might be useful for the scaffold design of salivary gland regeneration.