Physical properties imparted by genipin to chitosan for tissue regeneration with human stem cells: A review

- The quality of genipin (GEN) produced with green technology is instrumentally assessed.
- Minor amounts of GEN impart to chitosan (CHI) stability, stiffness, sensitivity to stimuli, fluorescence.
- Stem cells, growth factors, morphogenetic proteins are incorporated in CHI | GEN for tissue regeneration.
- Enhanced osteogenesis is obtained via osteoblast modulation with CHI | GEN in the presence of inorganics.
- Cartilage is regenerated by fibroblasts growing uniformly in porous CHI | GEN | collagen.

Genipin is a fully assessed non-cytotoxic crosslinking compound. The chitosan | genipin physical properties such as morphology, roughness, porosity, hydrophilicity, ζ-potential, surface area and surface energy exert control over cell adhesion, migration, phenotype maintenance and intracellular signaling in vitro, and cell recruitment at the tissue-scaffold interface in vivo. For example a therapy using fucose | chitosan | genipin nanoparticles encapsulating amoxicillin, based on the recognition of fucose by H. pylori, leads to sharply improved clinical results. A bioactive scaffold sensitive to environmental stimuli provides an alternative approach for inducing adipose stem cell chondrogenesis: the expression of specific genes, the accumulation of cartilage-related macromolecules and the mechanical properties are comparable to the original cartilage-derived matrix (CDM), thus making the CDM | genipin a contraction-free biomaterial suitable for cartilage tissue engineering. For the regeneration of the cartilage, chitosan | genipin permits to modulate matrix synthesis and proliferation of chondrocytes by dynamic compression; chondrocytes cultured on the composite substrate produce much more collagen-II and sulfated GAG. The main advantages gained in the bone regeneration area with chitosan | genipin are: acceleration of mineral deposition; enhancement of adhesion, proliferation and differentiation of osteoblasts; promotion of the expression of osteogenic differentiation markers; greatly improved viability of human adipose stem cells.