3D BIO-PRINTING

What’s it..?

3D bio-printing is a regenerative science and process for generating spatially-controlled cell patterns in 3D, where cell function and viability are preserved within the printed construct. Using 3D bio-printing for fabricating biological constructs typically involves dispensing cells onto a biocompatible scaffold using a successive layer-by-layer approach to generate tissue-like three-dimensional structures.

Why..?

Each day 79 receive organ each day while 18 will die from a lack of one

Most needed organs are kidneys, livers, lungs, hearts.

Conceptual Bio-printer

Bioprinter

The idea of 3d printers are from inkjet printers, driven by a motor, moves in horizontal strips across a sheet of paper. As it moves, ink stored in a cartridge sprays through tiny nozzles and falls on the page in a series of fine drops. The limitation of inkjet printers is that they only print in two dimensions -- along the x- and y-axes. A 3-D printer overcomes this by adding a mechanism to print along an additional axis, usually labeled the z-axis in mathematical applications. This mechanism is an elevator that moves a platform up and down. Fill the cartridge with plastic, and the printer will output a three-dimensional plastic widget. Fill it with cells, and it will output a mass of cells.

Continues…

Conceptually, bio-printing is really that simple. In reality, it's a bit more challenging because an organ contains more than one type of material. And because the material is living tissue, it needs to receive nutrients and oxygen. To accommodate this, bioprinting companies have modified their 3-D printers to better serve the medical community.

If you were to pull apart a bio-printer, as we'd love to do, you'd encounter these basic parts.

Bio-printer Components

Print head mount 

On a bio-printer, the print heads are attached to a metal plate running along a horizontal track. The x-axis motor propels the metal plate (and the print heads) from side to side, allowing material to be deposited in either horizontal direction.

Elevator

A metal track running vertically at the back of the machine, the elevator, driven by the z-axis motor, moves the print heads up and down. This makes it possible to stack successive layers of material, one on top of the next

Platform

A shelf at the bottom of the machine provides a platform for the organ to rest on during the production process. The platform may support a scaffold, a petri dish or a well plate, which could contain up to 24 small depressions to hold organ tissue samples for pharmaceutical testing. A third motor moves the platform front to back along the y-axis

Reservoirs

 The reservoirs attach to the print heads and hold the biomaterial to be deposited during the printing process. These are equivalent to the cartridges in your inkjet printer.

Print heads/syringes

   A pump forces material from the reservoirs down through a small nozzle or syringe, which is positioned just above the platform. As the material is extruded, it forms a layer on the platform.

Triangulation sensor

   A small sensor tracks the tip of each print head as it moves along the x-, y- and z-axes. Software communicates with the machine so the precise location of the print heads is known throughout the process..

Micro-gel 

 Unlike the ink you load into your printer at home, bio-ink is alive, so it needs food, water and oxygen to survive. This nurturing environment is provided by a micro-gel think gelatin enriched with vitamins, proteins and other life-sustaining compounds. Researchers either mix cells with the gel before printing or extrude the cells from one print head, micro-gel from the other. Either way, the gel helps the cells stay suspended and prevents them from settling and clumping.

Bioink 

Organs are made of tissues, and tissues are made of cells. To print an organ, a scientist must be able to deposit cells specific to the organ she hopes to build. For example, to create a liver, she would start with hepatocytes -- the essential cells of a liver -- as well as other supporting cells. These cells form a special material known as bioink, which is placed in the reservoir of the printer and then extruded through the print head. As the cells accumulate on the platform and become embedded in the microgel, they assume a three-dimensional shape that resembles a human organ.

Alternatively, the scientist could start with a bioink consisting of stem cells, which, after the printing process, have the potential to differentiate into the desired target cells. Either way, bioink is simply a medium, and a bioprinter is an output device

How do they print an organ. First, doctors make CT or MRI scans of

the desired organ. Next, they load the images into a

computer and build a corresponding 3-D blueprint of the structure using CAD software.

Combining this 3-D data with histological information collected from years of microscopic analysis of tissues, scientists build a slice-by-slice model of the patient's organ. Each slice accurately reflects how the unique cells and the surrounding cellular matrix fit together in three-dimensional space.

How do they print an organ.

After that, it's a matter of hitting File > Print, which sends the modeling data to the bio-printer.

The printer outputs the organ one layer at a time, using bio-ink and gel to create the complex multicellular tissue and hold it in place.

Finally, scientists remove the organ from the printer and place it in an incubator, where the cells in the bio-ink enjoy some warm, quiet downtime to start living and working together

Last step and the challenging one!

The final step of this process -- making printed organ cells behave like native cells -- has been challenging. Some scientists recommend that bio-printing be done with a patient's stem cells. After being deposited in their required three-dimensional space, they would then differentiate into mature cells, with all of the instructions about how to "behave." Then, of course, there's the issue of getting blood to all of the cells in a printed organ. Currently, bio-printing doesn't offer sufficient resolutions to create tiny, single-cell-thick capillaries. But scientists have printed larger blood vessels, and as the technology improves, the next step will be fully functional replacement organs, complete with the vascularization necessary to remain alive and healthy.

The printing process

Benefits

Artificial organ personalized using patients own cells

No DNA rejection Eliminate need for immunosuppressant drugs

needed after a regular organ transplant Eliminate organ donation No waiting period

Disadvantages

Printers cost hundreds of thousands of dollars

Possibly more expensive than regular organ transplant

Use of stem cells is still controversial Cost of using stem cells Not successfully created yet

Just look through some bioprinting projects which gonna going to change the world

3d bio-printing projects

Human heart

Researchers at the University of Louisville in Louisville, Kentucky said they have successfully printed parts of a human heart using by printing with a combination of human fat cells and collagen.

Human face

A man from Wales in the United Kingdom was in a motorcycle accident in 2012 and he has now received 3D printed implants on his face that successfully fixed injuries he sustained.  The project was done by the Centre for Applied Reconstructive Technologies in Surgery.

Liver tissue

In January, Organovo successfully printed samples of human liver tissue that were distributed to an outside laboratory for testing. The company is aiming for commercial sales later this year. The sets of 24 samples take about 30 minutes to produce. According to the company, the printed tissue responds to drugs similarly to a regular human liver.

Liver tissue

Scientists at Wake Forest School of Medicine designed a printer that can directly print skin cells onto burn wounds. The traditional treatment for severe burns is to cover them with healthy skin harvested from another part of the body, but often times there isn't enough. With this new machine, a scanner determines the size and depth of the skin, and layers the appropriate number of cells on the wound. Doctors only need a patch of skin one-tenth of the size of the wound to grow enough for this process.

Presented by : Muhammed Anees PK