Development of dual-triggered in situ gelling scaffolds for tissue engineering

Hydrogel-forming materials that mimic the three-dimensional architecture and properties of tissue are known to have a positive effect on cellular differentiation and growth. A subset of those are in situ gels, which utilise in vivo conditions like pH(e. g. acetate phthalate), temperature (e. g. poloxamer) and ionic concentration (e. g. Gelrite (TM)), and can be used to facilitate the delivery of cells to an affected tissue. Hence, we have developed in situ hydrogels based on gellan and hydroxypropylmethylcellulose (HPMC), which are known to be triggered through ions and temperature, respectively, as matrices to deliver cells. Gellan/HPMC blends had a lower gelation temperature than gellan alone crosslinked with calcium, suggesting the role of the dual trigger. Average storage modulus at a frequency of 10 Hz for gellan crosslinked with 3 mmol L-1 calcium was 4.53 x 10(3) Pa; for 9: gellan/HPMC crosslinked with 3 mmol L-1 calcium was 5.59 x 10(3) Pa; and for 8:2 gellan/HPMC crosslinked with 3 mmol L-1 calcium was 2.13 x 10(3) Pa, suggesting tunable stiffness by changing the gellan-to-HPMC ratio. Hydrophilicity was confirmed using goniometry with a contact angle much less than 90 degrees, facilitating the passage of cells and electrolytes when using the gels as scaffolds. The gels were also found to be porous and non-toxic to fibroblast cell line L929 and osteosarcoma cell line MG-63, which, when encapsulated within the gels, were able to grow and proliferate. These blended hydrogels are suitable as scaffolds to encapsulate cells, with tunable stiffness modulated by varying the concentration of gellan and HPMC. (C) 2014 Society of Chemical Industry