How to minimise cell damage during 3D Bioprinting
5 considerations to improve the biocompatibility of the 3D fabrication process
Three-dimensional (3D) Bioprinting is a novel and promising technology, which may help to address the serious problem of human organ shortage in health care. Nowadays, 3D bioprinting is successfully used in many areas including tissue engineering and regenerative medicine, where it has allowed researchers to print complex structures such as a blood vessel, heart valves, bone, cartilage, kidneys, skin, nerves, and other tissues.
3D Bioprinting differs from other forms of 3D cell culture and requires the user to control several factors which are relevant to the printing process, which may place extra strain on the cells used for printing.
1. Material properties
3D Bioprinting technology uses biomaterials to mimic the extracellular matrix (ECM), which promotes cell adhesion, growth, proliferation, migration, and differentiation. These materials should support cell metabolism and provide a similar environment to that which is found in vivo. The biomaterials used should have excellent biocompatibility and tunable mechanical strength. Hydrogels are promising materials for this application, as they can be optimised to meet both of these requirements.
2. Scaffold Structure
3D Bioprinting is aiming to fabricate organs with a high degree of similarity not only in shape but also in functionality with the human body. Therefore, the biocompatibility of biomaterials is the first parameter to be considered when fabricating scaffolds. The biological scaffold must simultaneously support the growth of different cell types, which may require specific mechanical properties, chemical gradients, cell populations, and geometric structures. The ideal material must have appropriate hydrophilicity, pH neutrality, and degradability. It needs to be biocompatible and mechanically stable. The cells are usually encapsulated in biodegradable hydrogels that mimic a tissue-like environment for building bioprinted ink. Hydrogels can be tuned to protect the cell contained within from the shear force generated in the printing process and maintain their bio-functions, such as the self-renewal ability and multi-lineage differentiation potency of stem cells.
3. Environmental control
The external factors such as temperature and humidity are also important factors, as they can affect cell growth and proliferation. Some research show that the survival rate of cells is best at a temperature between 29 and 31 degrees and with humidity levels maintained at 65-85%.
4. Printing precision
In 3D bioprinting, a long-term goal is to achieve controlled single cell deposition. Especially for complex multi-cellular organs, single-cell control can simulate the structure of the human body to closely mimic human organs. Unfortunately, existing bioprinting technologies cannot yet achieve single-cell control. Improving the accuracy of the printers, coupled with a reasonable control algorithm is an important way to enhance the function of the fabricated tissues and organs.
5. Sterile conditions
One of the key drivers of 3D bioprinting technology is to reproduce human organs for use in clinical transplantation. The printing process and final printed organs must, therefore, be sterile to eliminate the risk of infections. If the 3D printing process is time-consuming, the possibility of contamination is increased, and therefore decreasing printing time is a way to optimise 3D Bioprinting for this purpose.
Li, Jipeng et al. “Recent advances in bioprinting techniques: approaches, applications, and future prospects.” Journal of Translational Medicine (2016)
Zhang, B., Luo, Y., Ma, L. et al. “3D bioprinting: an emerging technology full of opportunities and challenges“ Bio-design and Manufacturing (2018)