Benzylaminated dextran-modified hydrogels: A long-term bioactive TGF- beta 1 carrier

Highly porous dextran-based hydrogels [in which various amounts (up to 16.6%, w/w) of a benzylaminated dextran (DMCB) exhibiting high affinity for TGF beta 1 was immobilized] were developed to achieve long-term retention of bioactive TGF beta 1 in situ. Unmodified hydrogels rapidly desorbed 80-90% compared with only 40-60% of the preloaded TGF beta 1 from the DMCB-modified hydrogels during a period of 21 days in PBS in vitro. TGF beta 1 release experiments (performed with high ionic strength solutions) indicated that formation of the complex between TGF beta 1 and functionalized hydrogels was governed by different interactions, depending on the degree of conjugation with DMCB: ionic interactions in the case of weakly conjugated matrices and nonionic interactions in highly conjugated matrices. Using cells containing a TGF beta -sensitive luciferase reporter gene, weakly DMCB-modified hydrogels sequestered bioactive TGF beta 1 in situ, giving much higher, long-term signaling performance than highly functionalized hydrogels. Because these biocompatible functionalized hydrogels can provide long-term bioactive TGF beta 1, they could be used as scaffolds for cells to stimulate and regulate human tissue repair processes.