Performance of new gellan gum hydrogels combined with human articular chondrocytes for cartilage regeneration when subcutaneously implanted in nude mice

摘要

Gellan gum is a polysaccharide that has been recently proposed by our group for cartilage tissueengineeringapplications. It is commonly used in the food and pharmaceutical industry and hasthe ability to form stable gels without the use of harsh reagents. Gellan gum can function as aminimally invasive injectable system, gelling inside the body in situ under physiological conditionsand efficiently adapting to the defect site. In this work, gellan gum hydrogels were combined withhuman articular chondrocytes (hACs) and were subcutaneously implanted in nude mice for 4 weeks.The implants were collected for histological (haematoxylin and eosin and Alcian blue staining),biochemical [dimethylmethylene blue (GAG) assay], molecular (real-time PCR analyses for collagentypes I, II and X, aggrecan) and immunological analyses (immunolocalization of collagen types I andII). The results showed a homogeneous cell distribution and the typical round-shaped morphologyof the chondrocytes within the matrix upon implantation. Proteoglycans synthesis was detected byAlcian blue staining and a statistically significant increase of proteoglycans content was measuredwith the GAG assay quantified from 1 to 4 weeks of implantation. Real-time PCR analyses showed astatistically significant upregulation of collagen type II and aggrecan levels in the same periods. Theimmunological assays suggest deposition of collagen type II along with some collagen type I. Theoverall data shows that gellan gum hydrogels adequately support the growth and ECM depositionof human articular chondrocytes when implanted subcutaneously in nude mice.