Pullulan-Based Scaffolds for Advanced Cell Culture: Tailoring Structural, Mechanical, and Biological Properties

Pullulan, a natural microbial polysaccharide composed of repeating maltotriose units, is widely explored as a candidate for advanced cell culture configurations, tissue engineering (TE), and regenerative medicine (RM). Due to its excellent biocompatibility, lack of immunogenicity, and structural flexibility, it serves as a versatile base material. Pristine pullulan exhibits high water solubility and lacks intrinsic signals for cell attachment and proliferation. However, the presence of nine reactive hydroxyl groups per repeating maltotriose unit enables extensive chemical functionalization to address these limitations. This review provides a comprehensive analysis of multi-functional design strategies used to tailor pullulan into distinct structural forms, such as hydrogels, porous scaffolds, electrospun fibrous membranes, thin films, 3D-printed scaffolds, and self-assembling nanosystems. Polymer blending, chemical modification, and crosslinking strategies are discussed in relation to scaffold microstructure, pore size, degradation rate, and mechanical properties. In addition, these structural and physicochemical properties are correlated with biological performance, including cell migration, proliferation, and differentiation. Pullulan-based materials are particularly suited for applications requiring extensive chemical tunability, such as injectable hydrogels, bioinks, and multifunctional delivery systems. However, their intrinsic bioinertness and limited mechanical strength generally require combination with complementary components to achieve effective cell adhesion and structural stability. Finally, current processing limitations and future strategies are discussed for translating pullulan-based systems into clinical applications.