title: Biofabrication using fibrous shape-morphing materials
Creators: name: Apsite, Indra
Publisher: name: University of Bayreuth
Year: 2020
Subjects: subject: electrospinning
subject: self-folding
subject: biofabrication
subject: skeletal muscle
subject: nerve guide conduits
subject: 4D biofabrication
subject: neuron cells
subject: 500
subject: 600

description: Even though the field of medicine is constantly growing and advancing, organ and tissue transplantation remains the standard treatment for life-threatening organ damage. As human life expectancy is constantly increasing, organ demand is greater than the supply of donated organs. Another serious issue with organ transplantation is immune rejection of donor organs. Nowadays, scientists consider tissue engineering as a possible solution to these problems. Even though tissue engineering has promise, fabrication of highly complex tissue with specific/ uniaxial cell alignment remains a significant problem. Another field in close contact with tissue engineering is biofabrication. Biofabrication can be defined as “the production of complex living and non-living biological products from raw materials such as living cells, molecules, extracellular matrices, and biomaterials”1. That is, biofabrication deals with fabrication of complex objects with biological functions. A novel biofabrication technique is 4D biofabrication, which assumes fabrication of complex 3D objects by shape-transformation of 2D and 3D objects in response to a specific stimulus. One of major advantage of this approach is that it allows high-resolution fabrication of hollow tubular structures with no use of sacrificial material and easy cell encapsulation. The aim of this work is development of methods for fabrication of fibrous shape-morphing structures, which shall allow 4D biofabrication of muscle and neural tissues. It is envisioned that fibrous shape-morphing materials will be able to provide high permeability needed for diffusion of oxygen and nutrition as well as structured topography that can be used for improved cell alignment and growth. The novelty of this work is the investigation of the biocomptability, degradability and cell-material interactions with the fibrous shape-morphing materials. Three different designs of biocompatible and degradable fibrous shape-morphing materials were prepared and investigated throughout this work. Different folding scenarios of the bilayer and multilayer fibrous shape-morphing materials have been discussed and explained based on various parameters: each layer thickness, the overall thickness of the bilayer/multilayer, number of the layers, environment temperature, choice of media, fiber alignment and shape of the material. Fibrous shape-morphing material interaction with three different cell types (fibroblasts, skeletal muscle cells, and neuron cells) has been described. High degradability has been achieved by the design of a fibrous bilayer system, that was able to achieve 70 % mass loss during a month of degradation without losing the stability of the self-rolled construct. Overall, though this work, it was shown that designed materials can be used for engineering of tissue with uniaxial cell alignment as skeletal muscle and neuron tissue. It was demonstrated fibrous shape-morphing material potential for functional muscle microtissue formation, that can be further developed by self-assembly into muscle bundles. Electrospinning of conductive fibers could improve both muscle and neuron cell differentiation.