Organ printing on a 3D printer or bioprinting is a promising technology for growing healthy and living organs to replace damaged or missing ones. In addition to a 3D printer, bioprinting requires an organ model, the patient’s cellular material, and an environment where the organ will be preserved until implantation.
Printed organs are better than prostheses and transplanted body parts. Their capabilities are identical to native organs and they are not rejected by the immune system if created from the patient’s DNA. Bioprinting will shorten the time it takes to get the right organ and save the lives of patients who need an immediate transplant.
Printing organs on a 3D printer has already been successfully tested on animals. Scientists at Northwestern University implanted artificial ovaries into sterilized mice and they gave birth to healthy mice. In the Chinese company Sichuan Revotek, rhesus macaques were implanted with blood vessels grown from the material of these same macaques.
So far, only internal tissues and skin are printed from human body parts. Reduced, but working copies of ears and noses are being created. The first printing of human organs is expected by 2030.
How bioprinting works
Research groups or companies are developing different bioprinting concepts:
Wireframe. Building living cells onto an inorganic substrate, disappearing as the natural connections between cells develop. The main challenge is to find a material that is as elastic or rigid as the organ to be replaced. It must degrade quickly so as not to interfere with the strengthening of the intercellular matrix and dissolve without leaving toxic compounds. Hydrogel, titanium, gelatin, synthetic and biopolymers are suitable for frame printing.
Frameless. The application of prefabricated cells to a hydrogel base. While the cells are in the printer, they are cooled and in thin hydrogel spheroids. During printing, the temperature rises to 36.6°, the spheroids dissipate and the cells gradually form a natural framework – the cell matrix – on their own. This printing is less common than framework printing – it appeared later and is more difficult to reproduce.
Mimicry. The technology of the future, involves creating complete copies of organs at once. For it, bioprinting at the molecular level is being developed and in-depth studies of the nature of cells are being conducted.
Ways to 3D print organs
Inkjet. The first bioprinting devices were inkjet, and conventional printers print by this method as well. They store biological material in cartridges, which is sprayed onto a hydrogel substrate like paint on paper. The disadvantages are inaccurate droplet emission and clogging of the spraying nozzle with possible death of cellular material. Inkjet organ printing on a printer is not suitable for viscous materials because they do not atomize. The field of application is limited to the restoration of bone, cartilage, muscle and skin. The advantages are low cost and mass reproducibility.
Microextrusion. This method is used in inorganic 3D printing. It uses a pneumatic feed of material into a movable extruder head, which deposits the cells. The more heads, the more accurate and faster the printer works. The disadvantage is that the denser the cells are stacked, the less they survive. For comparable stacking densities, more cells die from microextrusion printing than from inkjet printing. Advantages – suitable for 3D printing of high density organs, fine adjustment of material feed through pressure control.
Laser. Common in industry, but used in bioprinting. They use a laser to heat glass with a liquid cellular substrate. Excess pressure is created at the concentration point of the beam, which pushes the cells to the desired area of the substrate. A reflective element is placed between the beam and the glass with the biomaterial, which reduces the power of the beam. Disadvantages – increased metal content in the cells from the evaporation of the reflective element. Cost. Advantages – controllable down to individual cells, stacking of the biomaterial.