Injectable natural polymer compound for tissue engineering of intervertebral disc: In vitro study.

Intervertebral disc degeneration is recognized to be the leading cause for chronic low-back pain. Injectable hydrogel is one of the great interests for tissue engineering and cell encapsulation specially for intervertebral (IVD) affecting rate of regeneration success, in this study we assessed viscoelastic properties of a Chitosan-β glycerophosphate-hyaluronic acid, Chondroitin-6-sulfate, type 2 of Collagen, gelatin, fibroin silk (Ch-β-GP-HA-CS-Col-Ge-FS) hydrogel which was named as NP hydrogel that is natural extracellular matrix of IVD. Chitosan-based hydrogel was made in the ratio of 1.5%: 7%: 1%:1%:1%-1.5%-1% (Ch: β-GP: HA-CS-Col-Ge-FS). Gelation time and other rheological properties were studied using amplitude sweep and frequency sweep tests. Also, the cytotoxicity of the hydrogel invitro assessed by MTT and trypan blue tests. Morphology of the hydrogel and attachment of NP cells were evaluated by SEM. Our result showed that NP hydrogel in 4°C is an injectable transparent solution. It started gelation in 37°C after about 30min. Gelation temperature of NP hydrogel was 37°C. Storage modulus (G') of this hydrogel at 37°C was almost constant over a wide range of strain. MTT and trypan blue tests showed hydrogel was cytocompatible. The obtained results suggest that this hydrogel would be a natural and cytocompatible choice as an injectable scaffold for using in vivo study of IVD regeneration.