Tissue engineered intervertebral disc implantation in situ：an experimental study

English Keywords:Tissue engineering  Intervertebral disc  In vivo  Poly L-lactic-co-glycolic acid  Canine

English Abstract:

  【Abstract】 Objective：To construct tissue engineered poly L-lactic-co-glycolic acid（PLGA） scaffold-nucleus pulposus cells intervertebral disc and to investigate the in vivo performance of the composite and its morphology and function in a canine model.Method：Nucleus pulposus（NP） cells isolated from the lumbar intervertebral discs of Beagle dog were cultured and proliferated in vitro and seeded into a 3-D porous PLGA scaffold.The composite was tested in 18 beagle dogs which were randomly divided into 3 groups：nucleotomy alone（group A），nucleotomy with PLGA implantation（group B） and nucleotomy with PLGA scaffold/NP cells composite implantation（group C）.X-ray and MRI scan were performed before and after the operation.Evaluation of disc height，segment stability，biomechanics and immunohistochemical analysis were performed and their results were recorded.Result：All animals were alive after operation.4 weeks later，disc height decreased in all three groups，with group C less severe than group A and B（P<0.05）.Flexion-extension ROM of group A and B were higher than group C（P<0.05）.More remarkable disc degeneration was noted in group A and B which showed black disc than group C which showed gray disc on T2 weighted MRI with T2-weighted signal intensity of group A and B lower than group C（P<0.05）.No PLGA scaffolds structure was found at 4 weeks postoperatively，scar tissue formation was evidenced in group A and B，while PHK-26 positive cells were evidenced in group C 8 weeks later with amount of chondrocyte cells proliferation and matrix formation.Type Ⅰ and Ⅱ collagen were noted in all three groups 8 weeks later，and type Ⅱ collagen staining in group C was more severe than type Ⅰ，type Ⅰ collagen staining in group A and B was more severe than type Ⅱ.Conclusion：The NP cell-PLGA scaffold composite is degradable and the seed cells can release type Ⅰ and Ⅱ collagen which can prevent scar infiltration as well as reconstruction of segmental stability and alignment.