Anterior cruciate ligament (ACL) reconstructive surgery is a major health concern world-wide because of a large aging population and increased occurrence of sport-related injuries. Tissue engineering is a rapidly growing interdisciplinary field that offers a promising new approach for ACL repair. The aim of this project is to explore novel “smart” surgical fixation devices that not only secure a graft in place without strength failure, but also incorporate and release bioactive materials, intended to promote bone tissue growth. In order to facilitate bioactive reagent release, biopolymeric scaffolds with continuous micro-porous structure were developed. The morphology of the porous structures in the poly-L-lactic acid (PLLA) matrix reflects the differential influence of the concentration of sacrificial material (PS-polystyrene), phase separation levels of the immiscible polymers (PLLA and PS), and melt-blending conditions (Fig. 1) [1]. During removal of the sacrificial material, the chemical solvent might introduce some chemical reactant into the scaffolds. In order to assess the feasibility of using the micro-porous structures for medical applications, 7F2 osteoblasts were cultured on these scaffolds for 7 days. The attachment and proliferation of 7F2 cells on all scaffolds were assessed by fluorescent nuclear staining with Hoechst 33258 and phalloidin. The morphology of 7F2 osteoblasts on solid PLLA and PLLA/HA with 40% porous structure scaffolds till the 7 days pos-seeding was observed under confocal microscopy (Fig. 2A and B). The results showed that removal of the sacrificial material does not influence cell growth and the composites are biocompatible. Besides in vitro cytotoxicity test, in vivo test of all the micro-porous structural scaffolds was performed through rat subcutaneous surgery. Histological analysis (H&E staining) of the porous PLLA/HA with 40% pores retrieved from rat subcutaneous tissue 4 weeks postimplantation show that cells start to grow inside the porous scaffold (Fig. 3A). The morphology of surrounding extracellular matrix (ECM) growing on the scaffolds was observed under SEM. Figure 3B shows soft tissue attached onto PLLA/HA porous scaffold after 1 month post implantation time point, which indicates the good biocompatibility of the scaffolds. Based on these data we predict that these scaffolds will be suitable for inducing and sustaining bone tissue regeneration, and will be feasible for ACL repair.
Highly porous multiwalled carbon nanotube buckypaper using electrospun polyacrylonitrile nanofiber as a sacrificial material
