Non-planar bioprinting with molding assistance for irregular wound shape

Abstract

Most human organs and tissues have different shapes, which vary per individual. When printing biomedical scaffolds using material extrusion-based additive manufacturing bioprinters, sacrificial layers are generally used to support the suspended parts of the scaffold. However, the in-process generation of sacrificial layers is time-consuming and the scaffold can be damaged when removing the sacrificial layers. In this study, a novel non-planar grid slicing (NPGS) process was proposed for printing irregularly shaped tissues with low aspect ratios (for example, skin wounds), where the required 3D shape is formed following the deposition of non-planar paths, layer-by-layer. By stacking layers of bioink onto a non-planar support base, the NPGS process considerably reduced the total length of the deposition paths and number of fragmented paths. Therefore, it can reduce the use of costly bioink and improve the success rate of the scaffold printing. The proposed NPGS process and traditional planar slicing (TPS) process were used to fabricate scaffolds that conform to the shape and depth of two clinical wounds. Compared to TPS, NPGS reduced the total length of the deposition paths and number of fragmented paths (paths shorter than 5 mm) by 49.2% and 59.6%, respectively. In animal testing, a large irregular wound was created on the rat's dorsal skin and treated with tri-cell-laden hydrogel printed by the NPGS process, demonstrating full repair after 28 days. The NPGS process shows great potential for customized biofabrication in tissue engineering.

Keywords

• Tissue engineering
• Non-planar slicing
• Bioprinting
• Molding assistance
• Irregular wound shape