Additively Manufactured Multiphasic Bone-Ligament-Bone Scaffold for Scapholunate Interosseous Ligament Reconstruction
36 Pages Posted: 14 Jan 2019 First Look: Under Review
The scapholunate interosseous ligament (SLIL) is a commonly torn wrist ligament. Current surgical options for SLIL tears are suboptimal and these injuries alter carpal kinematics resulting in secondary osteoarthritis. This research aims to develop a novel multiphasic bone-ligament-bone (BLB) scaffold using 3D-printing and cell sheet technology for the reconstruction of the dorsal scapholunate interosseous ligament (SLIL). Multiphasic bone-ligament-bone scaffolds modelled from the dorsal component of the SLIL were 3D-printed with medical grade polycaprolactone (PCL). These comprised two bone compartments bridged by aligned PCL fibres mimicking the architecture of the native ligament. Mechanical testing of the BLB scaffolds showed that they were capable of withstanding physiological forces. The BLB construct was implanted ectopically into athymic rats and harvested at 2 and 8 weeks. Three experimental groups were utilised (i) BLB scaffold only control, (ii) bone morphogenetic protein (BMP) in the bone compartment of the BLB scaffold and (iii) BMP in the bone compartment and human cell sheets in the ligament of the BLB scaffold. The cell sheets were formed by culturing human bone marrow mesenchymal stem cells on tissue culture plastic for 21 days with or without ascorbic acid supplemented media. Cell sheets treated with ascorbic acid showed high DNA content and ECM deposition in vitro prior to implantation, and was therefore used for subsequent experiments. Analysis of cell sheets in vitro showed that harvesting and placement of cell sheets did not compromise cell viability and that the sheets were homogeneously distributed into the ligament compartment prior to implantation. Histological analysis of the in vivo samples demonstrated that the scaffolds were biocompatible, displayed good tissue integration and were highly vascularized. Bone formation was observed only at week 8 time-point and remained localised to the bone compartment. Cells in the ligament compartment were aligned and the graft underwent extensive tissue remodelling in vivo. This proof-of-concept study demonstrated that a 3D-printed multiphasic bone-ligament-bone scaffold can be successfully generated and implanted in a predictable manner for application in scapholunate ligament reconstruction. The specific architecture of the scaffold provided guiding properties for ligament fibre alignment and tissue regeneration.
Keywords: Scapholunate interosseous ligament, 3D-printing, cell sheet, bone-ligament-bone construct, scaffold, polycaprolactone
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