Bioactive electrospun scaffold for annulus fibrosus repair and regeneration

PURPOSE: Annulus fibrosus (AF) tissue engineering is gathering increasing interest for the development of strategies to reduce recurrent disc herniation (DH) rate and to increase the effectiveness of intervertebral disc regeneration strategies. This study evaluates the use of a bioactive microfibrous poly(L-lactide) scaffold releasing Transforming Growth Factor (TGF)-β1 (PLLA/TGF) for the repair and regeneration of damaged AF. METHODS: The scaffold was synthesized by electrospinning, with a direct incorporation of TGF-β1 into the polymeric solution, and characterized in terms of morphology and drug release profile. Biological evaluation was performed with bovine AF cells (AFCs) that were cultured on the scaffold up to 3 weeks to quantitatively assess glycosaminoglycans and total collagen production, using bare electrospun PLLA as a control. Histological evaluation was performed to determine the thickness of the deposited neo-ECM. RESULTS: Results demonstrated that AFCs cultured on PLLA/TGF deposited a significantly greater amount of glycosaminoglycans and total collagen than the control, with higher neo-ECM thickness. CONCLUSIONS: PLLA/TGF scaffold induced an anabolic stimulus on AFCs, mimicking the ECM three-dimensional environment of AF tissue. This bioactive scaffold showed encouraging results that allow envisaging an application for AF tissue engineering strategies and AF repair after discectomy for the prevention of recurrent DH.