Novel bilayered Gellan gum/Gellan gum hydroxyapatite scaffolds for osteochondral tissue engineering applications

摘要

Osteoarthritis is a major cause of disability during aging. By the age of60, close to 100% of the population will have histologic changes ofdegeneration in their knee cartilage (Loeser, 2000). Because of its avascularnature, cartilage has little capacity to self-regenerate. Despite theprogress already achieved in osteochondral regeneration, some limitationshave to be overcome. The formation of fibrocartilage has to beavoided and the innervation has to be improved. Further, one main featureto be promoted is the induction of vascularization in the bony partbut not in the cartilage part and to avoid de-differentiation processes. Apromising strategy could pass through the development and optimizationof novel culture systems. The ideal approach could integrate scaffoldspresenting regions with different physical characteristics,combined with different growth factors to support different stem cellsfates, regarding the complex tissue physiology to be regenerate. Thiswork aims to develop novel bilayered gellan gum (GG)/gellan gumhydroxyapatite(HAp) hydrogels based structures for osteochondral tissueengineering applications. Bilayered GG/GG-HAp hydrogels wereproduced by joining both solutions of GG 2% (w/v) with and withoutHAp (20% wt.) for bony and cartilage parts, respectively. The solutionswere introduced into a silicone mould with 20:10 mm (height anddiameter, respectively). Gelation of GG was promoted by immersion inPBS solution for 24 h. The architecture of the bilayered scaffolds wasinvestigated by micro-computed tomography. Results have shown thatthe freeze-dried bilayered scaffolds composed by low acyl GG(2%(w/v)/low acyl GG(2%(w/v)-HAp20%(w/w) possess a porosity of83.4 ± 0.8%, pore size of 279.3 ± 38.6 lm and interconnectivity of62.2 ± 5.4%. Degradability assays are being performed with the intentto use this system to culture human adipose derived stem cells inducingcell co-differentiation into chondrocytes and osteoblasts. Ultimately, the developed bilayered scaffolds will provide new therapeutic possibilities for the regeneration of osteochondral defects.