Gellan Gum Injectable Hydrogels for Cartilage Tissue Engineering Applications: In Vitro Studies and Preliminary In Vivo Evaluation

Abstract

Gellan gum is a polysaccharide that we have previously proposed for applications in the cartilage tissue engineering field. In this work, gellan gum hydrogels were tested for their ability to be used as injectable systems using simple processing methods, able to deliver and maintain chondrocytes by in situ gelation, and support cell viability and production of extracellular matrix (ECM). Rheological measurements determined that the sol-gel transition occurred near the body temperature at 39 degrees C, upon temperature decrease, in approximately 20 s. Gellan gum discs shows a storage compression modulus of around 80 kPa at a frequency of 1 Hz by dynamic mechanical analysis. Human articular chondrocytes were encapsulated in the gels, cultured in vitro for total periods of 56 days, and analyzed for cell viability and ECM production. Calcein AM staining showed that cell kept viable after 14 days and the histological analysis and real-time quantitative polymerase chain reaction revealed that hyaline-like cartilage ECM was synthesized. Finally, the in vivo performance of the gellan gum hydrogels, in terms of induced inflammatory reaction and integration into the host tissue, was evaluated by subcutaneous implantation in Balb/c mice for 21 days. Histological analysis showed a residual fibrotic capsule at the end of the experiments. Dynamic mechanical analysis revealed that the gels were stable throughout the experiments while evidencing a tendency for decreasing mechanical properties, which was consistent with weight measurements. Altogether, the results demonstrate the adequacy of gellan gum hydrogels processed by simple methods for noninvasive injectable applications toward the formation of a functional cartilage tissue-engineered construct and originally report the preliminary response of a living organism to the subcutaneous implantation of the gellan gum hydrogels. These are the two novel features of this work.

Modified gellan gum hydrogels for tissue engineering applications

“…Chondrocytes were shown to remain viable when encapsulated in GG hydrogels 63 and exhibited ECM production when implanted subcutaneously in nude mice 66 . 10 Injectable delivery of these chondrocyte-laden gels was also investigated, taking advantage of the ability of GG to form a gel under physiological conditions 67 . GG hydrogels were also used to encapsulate oligodendrocyte-like cells within the centre of a tubular structure fabricated by 3D extrusion printing of starch 68 .…”

A nanoparticulate injectable hydrogel as a tissue engineering scaffold for multiple growth factor delivery for bone regeneration

“…Solutions of xanthan are known to be pseudo plastic; stable to variations in pH, temperature, and salt concentrations; show a rapid regain of viscosity upon removal of shear stress; and show optimal suspension properties and high viscosity at low shear rates. 7 The versatility of gellan to be used as scaffolds, fibers, particles, or membranes as well as its ability to support human nasal chondrocytes growth and proliferation has been shown in studies by Oliveira et al 8,9 Studies with human and rat articular chondrocytes have also proven its potential as a promising material for cartilage tissue regeneration. 9,10 A gellan xanthan combination has been shown to be a promising injectable gel system that could act as a supporting matrix for cells to regenerate cartilage, by our group.…”

“…7 The versatility of gellan to be used as scaffolds, fibers, particles, or membranes as well as its ability to support human nasal chondrocytes growth and proliferation has been shown in studies by Oliveira et al 8,9 Studies with human and rat articular chondrocytes have also proven its potential as a promising material for cartilage tissue regeneration. 9,10 A gellan xanthan combination has been shown to be a promising injectable gel system that could act as a supporting matrix for cells to regenerate cartilage, by our group. 11 With an excellent water holding capacity and hydrophilicity, gellan xanthan gels show a gelling time of ,10 minutes at room temperature and ,5 minutes at 37°C which make them suitable for the intended application.…”

Injectable gellan gum hydrogels with autologous cells for the treatment of rabbit articular cartilage defects

“…19 In our previous works, it has been used to encapsulate both human nasal and articular chondrocytes in vitro, and has been tested in vivo by subcutaneous implantation in nude mice with human articular chondrocytes. [20][21][22] In this work, autologous cells [adipose stem cells (ASC) articular chondrocytes (AC)] were combined with gellan gum and injected in rabbit knee full thickness size defects. The results show that gellan gum constructs are able to efficiently regenerate hyaline-like cartilage tissue in the created defects.…”