Gellan gum injectable hydrogels for cartilage tissue engineering applications : in vitro studies and preliminary in vivo evaluation

摘要

Gellan gum is a polysaccharide that we have previously proposed for applications in the cartilage tissueengineering field. In this work, gellan gum hydrogels were tested for their ability to be used as injectable systemsusing simple processing methods, able to deliver and maintain chondrocytes by in situ gelation, and support cellviability and production of extracellular matrix (ECM). Rheological measurements determined that the sol–geltransition occurred near the body temperature at 39ºC, upon temperature decrease, in approximately 20 s. Gellangum discs shows a storage compression modulus of around 80 kPa at a frequency of 1Hz by dynamic mechanicalanalysis. Human articular chondrocytes were encapsulated in the gels, cultured in vitro for total periodsof 56 days, and analyzed for cell viability and ECM production. Calcein AM staining showed that cell kept viableafter 14 days and the histological analysis and real-time quantitative polymerase chain reaction revealed thathyaline-like cartilage ECM was synthesized. Finally, the in vivo performance of the gellan gum hydrogels, interms of induced inflammatory reaction and integration into the host tissue, was evaluated by subcutaneousimplantation in Balb/c mice for 21 days. Histological analysis showed a residual fibrotic capsule at the end of theexperiments. Dynamic mechanical analysis revealed that the gels were stable throughout the experiments whileevidencing 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 fornoninvasive injectable applications toward the formation of a functional cartilage tissue-engineered constructand originally report the preliminary response of a living organism to the subcutaneous implantation of thegellan gum hydrogels. These are the two novel features of this work.