00:00There are currently hundreds of thousands of people on transplant lists,
00:12waiting for critical organs like kidneys, hearts, and livers that could save their lives.
00:18Unfortunately, there aren't nearly enough donor organs available to fill that demand.
00:24What if, instead of waiting, we could create brand new, customized organs from scratch?
00:31That's the idea behind bioprinting,
00:34a branch of regenerative medicine currently under development.
00:38We're not able to print complex organs just yet,
00:41but simpler tissues, including blood vessels and tubes responsible for nutrient and waste exchange,
00:47are already in our grasp.
00:50Bioprinting is a biological cousin of 3D printing,
00:54a technique that deposits layers of material on top of each other
00:57to construct a three-dimensional object, one slice at a time.
01:02Instead of starting with metal, plastic, or ceramic,
01:05a 3D printer for organs and tissues uses bioink,
01:10a printable material that contains living cells.
01:14The bulk of many bioinks are water-rich molecules called hydrogels.
01:19Printed into those are millions of living cells,
01:22as well as various chemicals that encourage cells to communicate and grow.
01:27Some bioinks include a single type of cell,
01:30while others combine several different kinds to produce more complex structures.
01:35Let's say you want to print a meniscus,
01:38which is a piece of cartilage in the knee
01:40that keeps the shin bone and thigh bone from grinding against each other.
01:44It's made up of cells called chondrocytes,
01:46and you'll need a healthy supply of them for your bioink.
01:50These cells can come from donors whose cell lines are replicated in a lab,
01:55or they might originate from a patient's own tissue
01:58to create a personalized meniscus less likely to be rejected by their body.
02:03There are several printing techniques,
02:05and the most popular is extrusion-based bioprinting.
02:09In this, bioink gets loaded into a printing chamber
02:13and pushed through a round nozzle attached to a printhead.
02:17It emerges from a nozzle that's rarely wider than 400 microns in diameter,
02:23and can produce a continuous filament roughly the thickness of a human fingernail.
02:29A computerized image or file guides the placement of the strands,
02:33either onto a flat surface or into a liquid bath
02:36that'll help hold the structure in place until it stabilizes.
02:40These printers are fast, producing the meniscus in about half an hour,
02:45one thin strand at a time.
02:47After printing, some bioinks will stiffen immediately.
02:51Others need UV light or an additional chemical or physical process
02:55to stabilize the structure.
02:57If the printing process is successful,
02:59the cells in the synthetic tissue will begin to behave
03:03the same way cells do in real tissue,
03:05signaling to each other, exchanging nutrients, and multiplying.
03:10We can already print relatively simple structures like this meniscus.
03:14Bioprinted bladders have also been successfully implanted,
03:17and printed tissue has promoted facial nerve regeneration in rats.
03:23Researchers have created lung tissue, skin, and cartilage,
03:27as well as miniature, semi-functional versions of kidneys, livers, and hearts.
03:33However, replicating the complex biochemical environment of a major organ
03:38is a steep challenge.
03:40Extrusion-based bioprinting may destroy a significant percentage of cells in the ink
03:45if the nozzle is too small, or if the printing pressure is too high.
03:50One of the most formidable challenges is how to supply oxygen and nutrients
03:55to all the cells in a full-size organ.
03:59That's why the greatest successes so far have been with structures that are flat or hollow,
04:04and why researchers are busy developing ways to incorporate blood vessels
04:09into bioprinted tissue.
04:11There's tremendous potential to use bioprinting to save lives
04:15and advance our understanding of how our organs function in the first place.
04:19And the technology opens up a dizzying array of possibilities,
04:23such as printing tissues with embedded electronics.
04:27Could we one day engineer organs that exceed current human capability,
04:31or give ourselves features like unburnable skin?
04:36How long might we extend human life by printing and replacing our organs?
04:42And exactly who and what will have access to this technology and its incredible output?
04:50For more mind-blowing medical advancements,
04:53check out this video on hacking human genes to fight cancer,
04:57or this video to see how doctors use radioactive drugs to detect diseases.
05:03and until then, descend INIGHTS.
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