Efficiency Of An Intra-discal Injection Of Hepatocyte Growth Factor In Retarding The Degeneration Of Intervertebral Discs In Rat Model

Background:A poor nutritional supply to the cells of the avascular intervertebral discs, caused by dehydration of the extracellular matrix (ECM), is a major cause of intervertebral disc degeneration (IVD). Hepatocyte growth factor (HGF) exerts its effects on anti-fibrosis. Thus, HGF might play a role in retarding IVD.Objective:To evaluate the effectiveness of HGF in retarding IVD in a rat tail disc degeneration model.Methods:A disc degeneration model was induced by making a stab injury at the rat tail discs with a needle. Four weeks after needle puncture, a tri-block poly(lactide-co-glycolide)-poly(ethyleneglycol)-poly(lactide-co-glycolide) (PLGA-PEG-PLGA) polymer gel loaded with HGF or the gel-alone was injected into the discs. The effectiveness of HGF in retarding IVD was assessed by magnetic resonance imaging (MRI), histological score, vascular channel counts in endplates, and immunohistochemical evaluation for type Ⅰ collagen, type Ⅱ collagen, and bone morphogenetic protein 2 (BMP-2).Results:HGF-loaded gel injected into the nucleus pulposus (NP) showed a trend toward an increase in T2 signal intensity (P=0.028), type Ⅱ collagen staining in NP, and BMP-2 positive cells in the anulus fibrosus (AF), and toward a decrease in histological score (P=0.025) and type Ⅰ collagen staining in NP when compared with gel-alone-treated segments after disc degeneration induced by stab injury. Treating with HGF also showed a tendency to maintain the disc height (no statistical significance).Conclusion:Our findings suggest that HGF-loaded PLGA-PEG-PLGA gel injected into the degenerative discs can retard disc degeneration, as revealed by MRI, histological, and immunohistochemical evaluation.