Chitosan biomaterials induce branching morphogenesis in a model of tissue-engineered glandular organs in serum-free conditions.

Glandular organs feature ramified structures that are important for regulating physiological transport. The aim of this study was to develop a biomaterial-assisted, serum-free culture system to generate branching structures in explants of glandular organs. The fetal mammary gland (MG) was selected as the model organ to study the formation of glandular structure. Among the many biomaterials tested, chitosan demonstrated a superior effect in promoting branch formation in MGs. The morphogenetic effect toward MG branching was chitosan specific and not observed with other analogs with similar chemical compositions or structures. The molecular weight and specific linkages in the chitosan polymer were important parameters in mediating the morphogenetic effect. MG explants from different anatomical locations effectively promoted structure formation. Blocking endogenous fibroblast growth factor 10 (FGF10) inhibited the morphogenetic effect of chitosan, indicating that the chitosan effect was FGF10 dependent. This work demonstrates the feasibility of creating a serum-free system that is competent in facilitating tissue morphogenesis in MG. MG tissue structure can be efficiently generated in a biocompatible system, which was assisted by biomaterials.