Evaluation of hydrogels for bio‐printing applications

Abstract

In the United States alone, there are approximately 500,000 burn injuries that require medical treatment every year. Limitations of current treatments necessitate the development of new methods that can be applied quicker, result in faster wound regeneration, and yield skin that is cosmetically similar to undamaged skin. The development of new hydrogel biomaterials and bioprinting deposition technologies has provided a platform to address this need. Herein we evaluated characteristics of twelve hydrogels to determine their suitability for bioprinting applications. We chose hydrogels that are either commercially available, or are commonly used for research purposes. We evaluated specific hydrogel properties relevant to bioprinting applications, specifically; gelation time, swelling or contraction, stability, biocompatibility and printability. Further, we described regulatory, commercial and financial aspects of each of the hydrogels. While many of the hydrogels screened may exhibit characteristics suitable for other applications, UV-crosslinked Extracel, a hyaluronic acid-based hydrogel, had many of the desired properties for our bioprinting application. Taken together with commercial availability, shelf life, potential for regulatory approval and ease of use, these materials hold the potential to be further developed into fast and effective wound healing treatments.

Principles of the Kenzan Method for Robotic Cell Spheroid-Based Three-Dimensional Bioprinting

“…Besides the notion of 'scaffold' (which in this context would indicate a supportive material for bioprinting 4,[13][14][15][16] ), another term with a complex meaning which at times is confusing, is that of 'bioink'.…”

“…For example, for some authors a 'bioink' is whatever is used for bioprinting: any material, cells, or combination thereof [16][17][18] . But for many others, including the companies producing them, the 'bioinks' are the embedding bio-materials (the 'scaffolds') for bioprinting.…”

Progress in scaffold‐free bioprinting for cardiovascular medicine

“…Another favourable feature, making it preferable for large, cell‐homogenous, matrix‐rich tissues such as bone, cartilage, muscle, is its excellent scalability 9. However, although new biological bioinks are emerging, for example, collagen‐ or fibrin‐based,10, 11 the structural cohesion (the “glue”) is obtained by still non‐universal, sometimes proprietary and/or expensive polymeric materials in form of hydrogels 12. As these hydrogels are essentially soft materials, in order to provide the constructs with the necessary biomechanical properties, they require a hardening step, usually a chemically‐ or UV‐induced polymerization 13.…”

Advances in bioprinted cell-laden hydrogels for skin tissue engineering

“…By placing suitable cell types in appropriate positions, the tissue construct may then mature into a tissue/organ and late achieve functionality either inside a bioreactor or in vivo [22]. The ideal properties of hydrogels for bioprinting include stability, sterilization, biodegradability, adequate mechanical properties and swelling characteristics, but it is also required that both hydrogel chemistry and crosslinking mechanisms promote cell function [126]. Cells must not only survive to the printing process and remain viable, but should also be able to migrate within and from the implant, proliferate, establish cell-cell/cellmatrix interactions, and also secrete growth factors and other healing mediatiors.…”