Genipin crosslinked chitosan/PEO nanofibrous scaffolds exhibiting an improved microenvironment for the regeneration of articular cartilage

Abstract

Towards optimizing the growth of extracellular matrix to produce repair cartilage for healing articular cartilage (AC) defects in joints, scaffold-based tissue engineering approaches have recently become a focus of clinical research. Scaffold-based approaches by electrospinning aim to support the differentiation of chondrocytes by providing an ultrastructure similar to the fibrillar meshwork in native cartilage. In a first step, we demonstrate how the blending of chitosan with poly(ethylene oxide) (PEO) allows concentrated chitosan solution to become electrospinnable. The chitosan-based scaffolds share the chemical structure and characteristics of glycosaminoglycans, which are important structural components of the cartilage extracellular matrix. Electrospinning produced nanofibrils of ∼100 nm thickness that are closely mimicking the size of collagen fibrils in human AC. The polymer scaffolds were stabilized in physiological conditions and their stiffness was tuned by introducing the biocompatible natural crosslinker genipin. We produced scaffolds that were crosslinked with 1.0% genipin to obtain values of stiffness that were in between the stiffness of the superficial zone human AC of 600 ± 150 kPa and deep zone AC of 1854 ± 483 kPa, whereas the stiffness of 1.5% genipin crosslinked scaffold was similar to the stiffness of deep zone AC. The scaffolds were degradable, which was indicated by changes in the fibril structure and a decrease in the scaffold stiffness after seven months. Histological and immunohistochemical analysis after three weeks of culture with human articular chondrocytes (HACs) showed a cell viability of over 90% on the scaffolds and new extracellular matrix deposited on the scaffolds.

Polyethylene Oxide Assisted Fish Collagen-Poly-ε-Caprolactone Nanofiber Membranes by Electrospinning

“…The infrared spectra were shown in Figure 4 , and the absorption bands of different pure polymers (FC, PCL, PEO) were summarized in Table 2 . The absorption peak near 1238 cm −1 was the absorption peak of the amide III band, which was caused by the C-O stretching vibration [ 11 ], which was also related to the triple helix structure of collagen [ 21 ]. The characteristic peaks of type I collagen was more obvious after PEO removal.…”

Genipin does not reduce the initiation or propagation of microcracks in collagen networks of cartilage

“…Genipin, a cross-linker derived from plants, has received attention as a means to enhance mechanical properties of cartilage and tissue-engineered cartilage constructs [ 18 , 19 ], and as a potential repair for collagen damage [ 17 ]. Cartilage turns black in color when genipin reacts with the amino groups, and the color associates with oxygen radical-induced polymerization of genipin [ 28 ].…”

“…Cartilage turns black in color when genipin reacts with the amino groups, and the color associates with oxygen radical-induced polymerization of genipin [ 28 ]. Its low cytotoxicity makes genipin an appealing option to stimulate structural changes that may improve outcomes after severe mechanical loading [ 17 ].…”

“…1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride, or EDAC) can effectively increase the modulus of collagen networks, but can also create toxic cellular environments [ 15 ]. In contrast genipin, a well-known natural cross-linker for proteins including collagen, can improve the ultimate tensile stress of collagen networks [ 16 ] and promote regeneration of cartilage [ 17 ]. Genipin stimulates intra- and inter-molecular cross-links of the amino residues on tropocollagen or proteoglycan molecules [ 18 ].…”

Repair of annulus fibrosus defects using decellularized annulus fibrosus matrix/chitosan hybrid hydrogels

“…Chitosan, an abundant and renewable resource, has been the topic of extensive research in biomedicine because it has exceptional mechanical properties, is nontoxic, and has antimicrobial properties [19] . Genipin has been widely used in articular cartilage and intervertebral disc tissue engineering research because of its low cytotoxicity and good biological stability [20][21] .…”