MELT ELECTROSPINNING WRITING AND THE BIOFABRICATION OF VOLUMNOUS TISSUES AND ORGANS

摘要

Considering the complexity of natural tissues, a major challenge in tissue engineering applications is to produce three- dimensional (3D) structures that are anatomically accurate. This requires the manufacture of high resolution scaffolds in large volume (mL) dimensions, that can be effectively vascularized. Furthermore, the structural heterogeneity that occurs in living tissue needs to be replicated, at least in part. Multimodal constructs contain features across different length scales, and are a method to manufacture a high surface area scaffold with milliliter volumes. For example, electrospinning has been used in conjunction with fused deposition modelling (FDM) to create a "bimodal" scaffold that contained both small diameter and large diameter elements. In this instance, the ordered scaffold structure is provided by the FDM component, while the electrospun fibers fill up the pores between each FDM layer. While there has been a significant effort in developing similar techniques to manufacture multimodal substrates with a defined organization, the resolutions remain limited. In general, highly resolved scaffolds with micron-scale control are difficult to build in the centimeter scale-range. Additive manufacturing is poised to achieve complex, highly resolved and vascularized tissue constructs, through advances in both printing resolution and computer-directed fabrication based on customization. One additive manufacturing approach that could address this existing situation is melt electrospinning writing. This technique electrostatically stabilizes a falling molten thread, placing it accurately onto a collector without any jet break-up. It can generate organized 3D scaffolds with a precise and predictable layer-by-layer deposition with finely resolved fibers. This solvent-free approach provides a pathway to clinical products while addressing the need for 3D architecture requirements for a variety of tissue engineering applications. Examples of MEW scaffolds are shown in Figure 1.