Anisotropic Chitosan Scaffolds Generated by Electrostatic Flocking Combined with Alginate Hydrogel Support Chondrogenic Differentiation

Abstract

The replacement of damaged or degenerated articular cartilage tissue remains a challenge, as this non-vascularized tissue has a very limited self-healing capacity. Therefore, tissue engineering (TE) of cartilage is a promising treatment option. Although significant progress has been made in recent years, there is still a lack of scaffolds that ensure the formation of functional cartilage tissue while meeting the mechanical requirements for chondrogenic TE. In this article, we report the application of flock technology, a common process in the modern textile industry, to produce flock scaffolds made of chitosan (a biodegradable and biocompatible biopolymer) for chondrogenic TE. By combining an alginate hydrogel with a chitosan flock scaffold (CFS+ALG), a fiber-reinforced hydrogel with anisotropic properties was developed to support chondrogenic differentiation of embedded human chondrocytes. Pure alginate hydrogels (ALG) and pure chitosan flock scaffolds (CFS) were studied as controls. Morphology of primary human chondrocytes analyzed by cLSM and SEM showed a round, chondrogenic phenotype in CFS+ALG and ALG after 21 days of differentiation, whereas chondrocytes on CFS formed spheroids. The compressive strength of CFS+ALG was higher than the compressive strength of ALG and CFS alone. Chondrocytes embedded in CFS+ALG showed gene expression of chondrogenic markers (COL II, COMP, ACAN), the highest collagen II/I ratio, and production of the typical extracellular matrix such as sGAG and collagen II. The combination of alginate hydrogel with chitosan flock scaffolds resulted in a scaffold with anisotropic structure, good mechanical properties, elasticity, and porosity that supported chondrogenic differentiation of inserted human chondrocytes and expression of chondrogenic markers and typical extracellular matrix.

Electrostatic flocking of salt-treated microfibers and nanofiber yarns for regenerative engineering

“…The anisotropy imparted by the flocked layers contribute to the increased stiffness and compressive strength, though the mechanical characteristics of the PDMS (i.e., hysteresis looping and elastomeric behavior) are retained. The ability of flock fibers to induce anisotropy in a biomedical elastomer has not yet been reported, though several studies have sought to use a similar framework to create ultra-strong composite materials and reinforce hydrogels [ 66 , 67 ]. In addition to the anisotropy of the flocked fibers, the use of layered flocked structures contributes to the bulk material toughness.…”

Application of Alginate Hydrogels for Next-Generation Articular Cartilage Regeneration

“…With this goal, alginate was either chemically modified or engineered (sulfhydrylation, alkylation, dopamine modification) [349,354,359,361,376] or combined with other materials or compounds in order to generate mechanically stronger composite systems adapted for cartilage engineering [116,326,346,[350][351][352][353][355][356][357][358]360,[362][363][364][365][369][370][371][372]379].…”

“…Materials and compounds used to form composites with alginate include collagen [116,352], PRP [326], bovine cartilage matrix [346], agarose [352], polyvinyl alcohol (PVA) [364], poly(εcaprolactone) (PCL) [365], N,O-carboxymethyl chitosan/polyphosphate (N,O-CMC-polyP) [363], polyacrylamide (PAAm) [355,362,365], poly(L-lactic acid) (PLLA) [371], hyaluronic acid (HA) [360], polymethacrylate (PMA) [350], nanocellulose [351,358,379], poly(2-ethyl-2oxazoline) (PEOXA) [351], chondroitin sulfate [357], polyethylene glycol (PEG) with fibrin [370], and chitosan [353,356].…”

Stepwise Proliferation and Chondrogenic Differentiation of Mesenchymal Stem Cells in Collagen Sponges under Different Microenvironments

“…Cells embedded in hydrogels are surrounded by water-swollen networks that resemble the extracellular microenvironments surrounding cells in vivo [ 23 , 24 ]. The combination of porous scaffolds and hydrogels has been reported to facilitate cell loading [ 25 , 26 ]. In these studies, hydrogels have been used as a carrier to entrap the seeded cells in the porous structures, avoiding leakage of seeded cells from the interconnected pore structures of porous scaffolds.…”