Biomedical Engineering Reference
In-Depth Information
variability of the bioprinting process output. For example, lot-to-lot variability in the growth media can
affect the viability of living and biomolecular components of the bioink post printing. Similarly, the
viability of fabricated structures can be affected by the source of cells and their storage method prior to
printing, even when the bioprinting process parameters are held constant. During the development and
characterization of a bioprinting process for allogenic applications, it is critical that the appropriate-
ness of the selected cell source be determined from an application perspective, and its characteristics
be thoroughly analyzed and documented. Concepts such as crowd sourcing can be used during the
research and development phase to eliminate variability caused by the bioink material.
Measurement and in-process monitoring technologies:
A key technology gap to advance bioprint-
ing technologies for engineered tissue is the ability to monitor in real time the process of printing
cells and biological moieties. While optical methods are being utilized to monitor droplets and printed
constructs, currently there are limited options available to nondestructively evaluate the “living” com-
ponents within the printed constructs. For example, in the scale-up production of printed cellular con-
structs, how do we monitor both the placement and functionality of cells within the biomaterial? The
problem is even more challenging when encapsulated in 3D hydrogel. Real-time label-free monitoring
methods must be developed to advance the scalability and integration of the bioprinting process to eco-
nomically viable production. The data generated can also help to identify critical process parameters
and help implement statistical process control for the bioprinting processes. Ultimately these technolo-
gies will be needed to help scale-up or scale-out the process to help meet the demand for customized
tissue- and organs-on-demand.
3.5
CONCLUSION
Undoubtedly, the ability to accurately place cells and cellular constructs to form engineered tissue and
organoid systems by the definition of a digital model is powerful. The technologies presented offer
viable and high-throughput approaches to printing cells and hydrogels in a biocompatible and cell-
friendly environment. Spatial control, precise placement of multiple cell types, and high-throughput
speed when compared to manual methods are clearly the biggest advantages of the 3D bioprinting tech-
nology. When compared to microfabrication techniques such as microstamping and micromolding, the
biggest advantage of 3D bioprinting is the ability to define complex interior architecture in true three-
dimensions due to the layer by layer additive manufacturing approach taken by most bioprinting tech-
nologies. This bottom-up technology bridges microscale and mesoscale definition of engineered tissue,
thereby offering the possibility of addressing the challenge of building thick tissues and organ systems.
An immediate application of 3D bioprinting are the use of these systems to create disease models
to study pathophysiology, as complex
in vitro
tissue models to screen for new therapeutic drugs and
as systems to help achieve engineered meat and leather products. Maturation of these applications of
bioprinting will see some of the groundwork being laid to address the challenges highlighted in the
previous section. Lab-grown organs and functional tissue intended for human implantation will likely
see another decade of fundamental research activity before they have the possibility to become real ap-
plication scenarios. The future success and commercial viability of the process will depend on efforts to
address the challenges to adoption of bioprinting. The systems have the potential to be widely adopted
and integrated within conventional cell culture laboratories. They provide a new avenue for researchers
to ask research questions in the third dimension, thereby replicating the dynamics of
in vivo
cellular
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