Chitosan/γ-poly(glutamic acid) scaffolds with surface-modified albumin, elastin and poly-l-lysine for cartilage tissue engineering.

Cartilage has limited ability to self-repair due to the absence of blood vessels and nerves. The application of biomaterial scaffolds using biomimetic extracellular matrix (ECM)-related polymers has become an effective approach to production of engineered cartilage. Chitosan/γ-poly(glutamic acid) (γ-PGA) scaffolds with different mass ratios were prepared using genipin as a cross-linker and a freeze-drying method, and their surfaces were modified with elastin, human serum albumin (HSA) and poly-l-lysine (PLL). The scaffolds were formed through a complex between NH3+ of chitosan and COO- of γ-PGA, confirmed by Fourier transform infrared spectroscopy, and exhibited an interconnected porous morphology in field emission scanning electron microscopy analysis. The prepared chitosan/γ-PGA scaffolds, at a 3:1 ratio, obtained the required porosity (90%), pore size (≥100µm), mechanical strength (compressive strength>4MPa, Young's modulus>4MPa) and biodegradation (30-60%) for articular cartilage tissue engineering applications. Surface modification of the scaffolds showed positive indications with improved activity toward cell proliferation (deoxyribonucleic acid), cell adhesion and ECM (glycoaminoglycans and type II collagen) secretion of bovine knee chondrocytes compared with unmodified scaffolds. In caspase-3 detection, elastin had a higher inhibitory effect on chondrocyte apoptosis in vitro, followed by HSA, and then PLL. We concluded that utilizing chitosan/γ-PGA scaffolds with surface active biomolecules, including elastin, HSA and PLL, can effectively promote the growth of chondrocytes, secrete ECM and improve the regenerative ability of cartilaginous tissues.

Cryopreserved chondrocytes in porous biomaterials with surface elastin and poly-L-lysine for cartilage regeneration.

The ability of cryopreserved chondrocytes to revitalize and propagate is a key biotechnology in cartilage regeneration. This study shows the formation of neocartilage from cryopreserved chondrocytes in scaffolds grafted with elastin and poly-L-lysine. Cryopreserved chondrocytes in elastin- and poly-L-lysine-grafted constructs were cultured in a dynamic bioreactor and assessed by biochemical assay and staining. Elastin demonstrated a better efficacy for recruiting cryopreserved chondrocytes onto the pore surface of constructs than poly-L-lysine. However, surface elastin and poly-L-lysine did not significantly enhance the biocompatibility to cryopreserved chondrocytes. Chondrocytes multiplied from cryopreserved chondrocytes in elastin-grafted constructs is faster than that in poly-L-lysine-grafted constructs. In addition, elastin could stimulate cryopreserved chondrocytes to synthesize more glycosaminoglycans and collagen than poly-L-lysine. Porous biomaterials with surface elastin and poly-L-lysine can maintain active chondrocytic proliferation and extracellular matrix secretion from chondrocytes with appropriate cryopreservation.