Biofabrication of Hydrogel Constructs
Hydrogels are three dimensional (3D) hydrophilic networks with the ability to absorb and retain large amounts of water without dissolution, as a result of the establishment of physical or chemical bonds between the polymeric chains. Hydrogels obtained fro
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Abstract Hydrogels are three dimensional (3D) hydrophilic networks with the ability to absorb and retain large amounts of water without dissolution, as a result of the establishment of physical or chemical bonds between the polymeric chains. Hydrogels obtained from either natural or synthetic polymers are attractive materials for tissue engineering applications due to their excellent biocompatibility, biodegradability, elasticity and compositional similarities to the extracellular matrix. Several techniques have been explored to produce hydrogel meshes, films or 3D constructs for cell attachment, differentiation and proliferation or to release drugs and growth factors according to specific release profiles. This chapter describes the current state-of-the-art of biomanufacturing additive processes to produce hydrogel constructs for tissue engineering. Biomanufacturing processes are described in detail and the major advantages and limitations outlined. Keywords Biofabrication • Tissue engineering • Hydrogels • Scaffolds • Stereolithography • Personalized medicine
1 Introduction Tissue engineering is a multidisciplinary field that requires the combined effort of cell biologists, engineers, material scientists, mathematicians, geneticists, and clinicians towards the development of biological substitutes that restore, maintain,
R.F. Pereira • H.A. Almeida • P.J. Bártolo () Centre for Rapid and Sustainable Product Development, Polytechnic Institute of Leiria, Leiria, Portugal e-mail: [email protected] J. Coelho (ed.), Drug Delivery Systems: Advanced Technologies Potentially Applicable in Personalised Treatment, Advances in Predictive, Preventive and Personalised Medicine 4, DOI 10.1007/978-94-007-6010-3__8, © Springer ScienceCBusiness Media Dordrecht 2013
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Fig. 1 Fundamental strategies for tissue engineering: bottom-up and top-down approaches [3]
or improve tissue function [1]. Two fundamental strategies can be considered [1–5] (Fig. 1): 1. Bottom–up approaches; 2. Top–down approaches. The bottom-up approach employs different techniques for creating modular tissues, which are then assembled into engineered tissues with specific microarchitectural features [6]. Tissue modules can be created through self-assembled aggregation, microfabrication of cell-laden hydrogels, fabrication of cell sheets or direct printing. The ability of cell aggregates to fuse is based on the concept of tissue fluidity, according to which embryonic tissues can be considered as liquids [7]. The major drawback of this approach is that some cell types are unable to produce sufficient extracellular matrix (ECM), migrate or form cell-cell junctions [3]. The top-down or scaffold-based approach is based on the use of a temporary scaffold that provides a substrate for implanted cells and a physical support to organize the formation of the new tissue [1, 8]. In this approach, transplanted cells adhere to the scaffold, proliferate, secrete their own ECM and stimulate new tissue formation. The top-down approach is the mos
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