Masoud Ghorbani - Department of Tissue Engineering and Applied Cell Sciences, Faculty of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
Jafar Ai - Department of Tissue Engineering and Applied Cell Sciences, Faculty of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
Mohammad Reza Nourani - Chemical Injury Research Center (CIRC), Biotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
Mahmoud Azami - Department of Tissue Engineering and Applied Cell Sciences, Faculty of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.

Intervertebral disc degeneration is recognized to be the leading cause of 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-CSCol-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: βGP: 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 in vitro 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 at 4 °C is an injectable transparent solution. It started gelation at 37 °C after about 30 min. 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.

Injectable hydrogel, Intervertebral disc, Tissue engineering