A bioprinted human ear from Princeton University. Credit: Princeton University
Today, much of the research around 3D bioprinting tissue and organs revolves around laying down enough cells in an abiotic substrate outside a living body, so they can culture and then be implanted where needed.
One company, however, believes a better method will be to print the cells inside of a human host, and take advantage of the body's natural ability to incubate and promote cell reproduction. This method is called in-vivo.
William Warren, vice president of vaccine manufacturer Sanofi Pasteur's VaxDesign Campus, explained to attendees of the RAPID 3D Printing Conference here this week that in-vivo bioprinting is also the least invasive procedure.
Sanofi Pasteur, a division of pharmaceutical company Sanofi, is the largest company dedicated entirely to vaccine development. Recently, it developed a bioprinting method that can extrude tissues of varying thicknesses to build constructs that living cells can grow around to form tissues.
The technology has allowed Sanofi Pasteur to print everything from collagen, a protein that connects tissues, to fibrinogen, the body's clotting agent.
Warren believes that before reproducing organs in vivo, 3D bioprinting will succeed in conquering "low-hanging fruit" first, such as reproducing auditory tissue for hearing, skin, tissue for vision and endoskeletons such as vertebrae. In fact, Warren believes, science will be able to bioprint organs outside of the body within five to seven years.
"I think we'll do it in vitro first, and that's being done very successfully now," Warren said. "But, I think long-term it will be in vivo."
In the meantime, bioprinting is mainly being used for drug testing, a form of personalized medicine where a patient's tissue can be cultivated and then used to test the effectiveness or toxicity of drugs.
Sanofi Pasteur's bioprinting method, which looks like a robotically controlled pen dispensing ink, has allowed it to lay down various tissues onto organs gently enough to not damage existing tissue. Company researchers have even been able to print on water without breaking the surface.
"We haven't figured out how to walk on water, but we have figured out how to print on water," Warren quipped.
To date, Sanofi Pasteur has been able to print various tissues on the organs of dead animals, to a height of about one millimeter.
However, there are significant hurdles to creating functioning organ tissue, the greatest of which is being able to produce a vascular infrastructure significant enough to feed the tissue with nutrients and oxygen. Vasculature is extremely complicated, Warren noted.
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