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

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.

Genipin-Crosslinked Chitosan Gels and Scaffolds for Tissue Engineering and Regeneration of Cartilage and Bone.

The present review article intends to direct attention to the technological advances made since 2009 in the area of genipin-crosslinked chitosan (GEN-chitosan) hydrogels. After a concise introduction on the well recognized characteristics of medical grade chitosan and food grade genipin, the properties of GEN-chitosan obtained with a safe, spontaneous and irreversible chemical reaction, and the quality assessment of the gels are reviewed. The antibacterial activity of GEN-chitosan has been well assessed in the treatment of gastric infections supported by Helicobacter pylori. Therapies based on chitosan alginate crosslinked with genipin include stem cell transplantation, and development of contraction free biomaterials suitable for cartilage engineering. Collagen, gelatin and other proteins have been associated to said hydrogels in view of the regeneration of the cartilage. Viability and proliferation of fibroblasts were impressively enhanced upon addition of poly-l-lysine. The modulation of the osteocytes has been achieved in various ways by applying advanced technologies such as 3D-plotting and electrospinning of biomimetic scaffolds, with optional addition of nano hydroxyapatite to the formulations. A wealth of biotechnological advances and know-how has permitted reaching outstanding results in crucial areas such as cranio-facial surgery, orthopedics and dentistry. It is mandatory to use scaffolds fully characterized in terms of porosity, pore size, swelling, wettability, compressive strength, and degree of acetylation, if the osteogenic differentiation of human mesenchymal stem cells is sought: in fact, the novel characteristics imparted by GEN-chitosan must be simultaneously of physico-chemical and cytological nature. Owing to their high standard, the scientific publications dated 2010-2015 have met the expectations of an interdisciplinary audience.

Emerging biomedical applications of nano-chitins and nano-chitosans obtained via advanced eco-friendly technologies from marine resources.

The present review article is intended to direct attention to the technological advances made in the 2010-2014 quinquennium for the isolation and manufacture of nanofibrillar chitin and chitosan. Otherwise called nanocrystals or whiskers, n-chitin and n-chitosan are obtained either by mechanical chitin disassembly and fibrillation optionally assisted by sonication, or by e-spinning of solutions of polysaccharides often accompanied by poly(ethylene oxide) or poly(caprolactone). The biomedical areas where n-chitin may find applications include hemostasis and wound healing, regeneration of tissues such as joints and bones, cell culture, antimicrobial agents, and dermal protection. The biomedical applications of n-chitosan include epithelial tissue regeneration, bone and dental tissue regeneration, as well as protection against bacteria, fungi and viruses. It has been found that the nano size enhances the performances of chitins and chitosans in all cases considered, with no exceptions. Biotechnological approaches will boost the applications of the said safe, eco-friendly and benign nanomaterials not only in these fields, but also for biosensors and in targeted drug delivery areas.