The development and manufacture of biological tissues are major socio-economic issues valued at 15 billion dollars in 2014 and is expected to double by 2018. Applications of these tissues concern both the industrial sector (cosmetics and pharmaceuticals) and regenerative medicine.
To cope with the limitations of conventional methods of tissue engineering, BioPrinting uses the principles of 3D printing, and so proceeds from the layer – by – layer assembly of tissue components, such as cells and extracellular matrix.
Laser-Assisted Bioprinting, as opposed to the conventional methods of tissue engineering and extrusion-based bioprinting, allows 3D positioning of cells with micrometric resolution and unmatched precision. It currently is the highest resolution bioprinting technology.
A laser pulse is focused on a cartridge (ie, a ink film spread on a glass plate) containing the cells to print; the laser crates an ink jet directed to a substrate, on which the "microdroplets", that is to say, the cells, land. By monitoring the physical conditions of ejection (energy, viscosity , …) the volume of the droplets is precisely controlled (~ picolitre ). The patterns of cells are obtained by a quick scan of the cartridge by the laser resulting in the formation of 10 000 droplets per second.
Laser-Assisted Bioprinting's greatest asset, its high printing resolution, allows the integration of more information and details into the tissue, thus making possible to reproduce the complexity of genuine biological tissues. Among the details are not only the microscopic 3D position of tissue components (such as cells and extra-cellular matrix elements), but also the projection of their evolution in time (the "fourth dimension", hence the name) up to the emergence of forms and special functions.
Our 4D Bioprinting approach to the needs of custom human tissue is as follows :
A digital file describing the architecture of biological tissues is produced by CAD. The information in this file involves both the initial position (x, y, z) of the tissue components (cells, extra-cellular matrix) and a projection of their evolution in time.
In this phase, the 3D digital file is cut into slices and the print settings are adjusted to the physical properties of the inks to be used.
The printing is done by depositing successive layers of micro-droplets made out of biological ink.
The fourth dimension is the time dimension associated with the self-organization of cellular processes (cell communication, cell interaction, extra-cellular matrix).
Printed organic tissues will be used as predictive models to evaluate the toxicity and efficacy of new therapeutic molecules and new ingredients for cosmetics (see Solutions).