INTRODUCTION: Annulus fibrosus (AF) tissue engineering is reaching increasing interest in developing strategies to both reduce recurrent disc herniation (DH) rate and increase effectiveness of intervertebral disc regeneration techniques. This study evaluate the use of a bioactive microfiber scaffold in Poly‐L‐Lactic Acid (PLLA) releasing the growth factor TGF‐β1 and investigate both cell toxicity and the extracellular matrix produced by bovine AF cells (bAFCs) and human mesenchymal stem cells (hMSCs) cultured on these scaffolds in vitro.
METHODS: Scaffolds were fabricated by electrospinning a PLLA solutions loaded with TGF‐β1 and characterized in terms of morphology and release rate of TGF‐β1. Bare PLLA scaffolds were use as control. bAFCs and hMSCs were cultured on the scaffolds and cell toxicity was evaluated at 4, 6 and 24 hours. bAFCs were seeded at the density of 5x105 cell/cm2 on the scaffold and cultured for 3 weeks. bAFCs were tested to quantitatively assess glycosaminoglycans (DMMB assay) and total collagen production (Sirus Red Assay). Histology was performed and the neo‐ECM thickness measured.
RESULTS: PLLA and PLLA/TGF‐β1 membranes were composed by fibers with diameter of 1.5±0.9μm and 0.6±0.2μm respectively. The scaffolds were not toxic for both hMSCs and bAFCs at all time points. PLLA/TGF‐β1 membranes released TGF‐β1. bAFCs cultured on PLLA/TGF‐β1 deposited a significant greater amount of glycosaminoglycans and total collagen than the control with higher neo‐ECM thickness.
DISCUSSION: PLLA/TGF‐β1 scaffold releasing TGF‐β1 induces an anabolic stimulus on bAFCs mimicking the ECM three‐dimensional environment of AF tissue. This bioactive scaffold shows encouraging results which could allow to find an application to repair the AF after discectomy and prevent recurrent DH. The scaffold could be associated with hMSCs for tissue engineering strategy in the treatment of intervertebral disc degeneration.