Regeneration of Intervertebral Disc by Stem Cell and Injectable Hydrogel in Animal Model

Background and Aim: Intervertebral disc degeneration is recognized tobe the leading cause for chronic low-back pain which occur because ofstructural damage of disc and is caused by herniation. Current methodsfor treatment of degeneration are artificial disc and prostheses but thereare caused by the limitation of movement and are invasive. Advancemethod for regeneration is cell and hydrogel In this study injectablehydrogel prepared that was similar to the extracellular matrix of the disc.Finally, hydrogel with nucleus pulposus (NP) cells and BMSCs injected todegenerated disc model and survey effects of its regenerationMethods: Injectable hydrogel synthesis with chitosan, B glycerolPhosphate, collagen, gelatin, hyaluronic acid, chondroitin 6 sulfate,and fibroin silk. Bone marrow mesenchymal stem cells extracted fromrabbit and cultured and differentiated to NP cells and another groupundifferentiated. Rheology, MTT, trypan blue, SEM used for evaluationof hydrogel. Discs 3-6 in animal model degenerated using by needle andinjection of papain. The degenerated discs divided into 4 groups: group 1was disc 3(L3-L4) that used as control group 2 was disc 4(L4-L5) that wasdegenerated but without cell and hydrogel injection. Group 3 was disc5(L5-L6) that encapsulated BMSc in hydrogel injected. Group 4 was disc6(L6-L7) that encapsulated NP cells in hydrogel injected. Finally, effectsregeneration of cells and hydrogel in animal model evaluated by MRI,histology, immunofluorescent and RT-PCR.Results: Results of rheology showed that gelation of hydrogel startedat 37°C after about 30 min. Rheological properties showed suitablemechanical properties of hydrogel and too. MTT and trypan blue testsindicated hydrogel was cytocompatible. Results of histology and immunefluorescent of rabbit IVD post injection of hydrogel-NP cells and hydrogel-BMSc determined high expression and production of extracellular matrixpost injection of NP cell-hydrogel in degenerated IVD. MRI indicated signal intensity and high of disc increased in the hydrogel-NP group.Conclusion: Our study suggests using of compound hydrogel-NP cell isexcellent for regeneration of IVD and it could use for regeneration ofdegenerated IVD in the human. It needs that perform our results in thebig animal before clinical trial.

Keywords:

Intervertebral Disc , Low back pain , Nucleus pulposus cells , Injectable , Chitosan , Collagen , Chondroitin sulfate , Fibroin silk , Hyaluronic acid , Gelatin