Hydrogels as Scaffold Materials

2 Hydrogels as Scaffold Materials 3.8.2.1 Tissue Engineering and Scaffolds 

Tissue engineering aims to replace, repair, or regenerate tissue or organ function and to create artificial tissues and organs for transplantation [67]. As previously mentioned, hydrogels are an attractive scaffolding material (3D matrix) for cells as they are structurally similar to the natural extracellular matrix (ECM) of many tissues. 

A number of different methods have been described in the literature for preparing porous stmctures to be employed as prefabricated tissue engineering scaffolds. Each of these techniques presents its own advantages, but none are free of drawbacks [73-75]. 

In the following, some conventional but also microengineering fabrication techniques for hydrogel scaffolds will be presented. 

Instead of single porogen particles, bulk polymer scaffold templates (e.g., made from PLGA) can be utilized for the production of macroporous hydrogels. Therefore, the hydrogel precursor solution is cast and cured around the scaffold. After degradation of the polymer scaffold with a suitable chemical, a porous hydrogel matrix is left behind. 

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Hydrogels as scaffold material in tissue engineering which contain human cells in order to repair tissue (Tsang and Bhatia 2004 Cushing and Anseth... 

Jiang, B., Waller, T.M., Larson, J.C., Appel, A.A., Brey, E.M., 2013. Fibrin-Loaded porous poly(ethylene glycol) hydrogels as scaffold materials for vascularized tissue formation. Tissue Engineering Part A 19 (1—2), 224—234. 

The behavior of stem cells in a 3D environment is well worth studying, since most practical applications of tissue repair and regeneration are accomplished by materials with a 3D structure, such as scaffolds, hydrogels, fibrous meshes, and microspheres. 

For example, stereolithography can be used. It is a liquid-based technique that utilizes LBL curing of a photosensitive hydrogel precursor solution by means of a laser. Alternatively, nozzle-based systems are applied. They process the material chemically as it passes through the nozzle (ink-jet printing, 3D printing cf. Section 3.10). Cells and biomolecules can be simultaneously printed with the scaffold material [79]. 

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