1 00:00:06,742 --> 00:00:12,052 There are currently hundreds of thousands of people on transplant lists, 2 00:00:12,052 --> 00:00:16,399 waiting for critical organs like kidneys, hearts, and livers 3 00:00:16,399 --> 00:00:18,449 that could save their lives. 4 00:00:18,449 --> 00:00:19,609 Unfortunately, 5 00:00:19,609 --> 00:00:24,619 there aren’t nearly enough donor organs available to fill that demand. 6 00:00:24,619 --> 00:00:26,583 What if instead of waiting, 7 00:00:26,583 --> 00:00:31,123 we could create brand-new, customized organs from scratch? 8 00:00:31,123 --> 00:00:33,783 That’s the idea behind bioprinting, 9 00:00:33,783 --> 00:00:38,063 a branch of regenerative medicine currently under development. 10 00:00:38,063 --> 00:00:41,273 We’re not able to print complex organs just yet, 11 00:00:41,273 --> 00:00:44,563 but simpler tissues including blood vessels and tubes 12 00:00:44,563 --> 00:00:47,503 responsible for nutrient and waste exchange 13 00:00:47,503 --> 00:00:49,683 are already in our grasp. 14 00:00:49,683 --> 00:00:53,743 Bioprinting is a biological cousin of 3-D printing, 15 00:00:53,743 --> 00:00:57,479 a technique that deposits layers of material on top of each other 16 00:00:57,479 --> 00:01:01,989 to construct a three-dimensional object one slice at a time. 17 00:01:01,991 --> 00:01:05,191 Instead of starting with metal, plastic, or ceramic, 18 00:01:05,191 --> 00:01:09,751 a 3-D printer for organs and tissues uses bioink: 19 00:01:09,751 --> 00:01:13,622 a printable material that contains living cells. 20 00:01:13,622 --> 00:01:18,892 The bulk of many bioinks are water-rich molecules called hydrogels. 21 00:01:18,892 --> 00:01:21,839 Mixed into those are millions of living cells 22 00:01:21,839 --> 00:01:26,679 as well as various chemicals that encourage cells to communicate and grow. 23 00:01:26,679 --> 00:01:29,846 Some bioinks include a single type of cell, 24 00:01:29,846 --> 00:01:35,366 while others combine several different kinds to produce more complex structures. 25 00:01:35,366 --> 00:01:37,740 Let’s say you want to print a meniscus, 26 00:01:37,740 --> 00:01:39,910 which is a piece of cartilage in the knee 27 00:01:39,910 --> 00:01:44,040 that keeps the shinbone and thighbone from grinding against each other. 28 00:01:44,040 --> 00:01:46,820 It’s made up of cells called chondrocytes, 29 00:01:46,820 --> 00:01:50,520 and you’ll need a healthy supply of them for your bioink. 30 00:01:50,520 --> 00:01:55,320 These cells can come from donors whose cell lines are replicated in a lab. 31 00:01:55,320 --> 00:01:58,339 Or they might originate from a patient’s own tissue 32 00:01:58,339 --> 00:02:03,489 to create a personalized meniscus less likely to be rejected by their body. 33 00:02:03,489 --> 00:02:05,416 There are several printing techniques, 34 00:02:05,416 --> 00:02:09,476 and the most popular is extrusion-based bioprinting. 35 00:02:09,476 --> 00:02:13,096 In this, bioink gets loaded into a printing chamber 36 00:02:13,096 --> 00:02:17,426 and pushed through a round nozzle attached to a printhead. 37 00:02:17,426 --> 00:02:23,526 It emerges from a nozzle that’s rarely wider than 400 microns in diameter, 38 00:02:23,526 --> 00:02:26,123 and can produce a continuous filament 39 00:02:26,123 --> 00:02:29,173 roughly the thickness of a human fingernail. 40 00:02:29,173 --> 00:02:33,433 A computerized image or file guides the placement of the strands, 41 00:02:33,433 --> 00:02:36,853 either onto a flat surface or into a liquid bath 42 00:02:36,853 --> 00:02:40,743 that’ll help hold the structure in place until it stabilizes. 43 00:02:40,743 --> 00:02:45,133 These printers are fast, producing the meniscus in about half an hour, 44 00:02:45,133 --> 00:02:47,843 one thin strand at a time. 45 00:02:47,843 --> 00:02:51,533 After printing, some bioinks will stiffen immediately; 46 00:02:51,533 --> 00:02:55,723 others need UV light or an additional chemical or physical process 47 00:02:55,723 --> 00:02:57,592 to stabilize the structure. 48 00:02:57,592 --> 00:02:59,972 If the printing process is successful, 49 00:02:59,972 --> 00:03:01,762 the cells in the synthetic tissue 50 00:03:01,762 --> 00:03:05,502 will begin to behave the same way cells do in real tissue: 51 00:03:05,502 --> 00:03:09,702 signaling to each other, exchanging nutrients, and multiplying. 52 00:03:09,702 --> 00:03:13,912 We can already print relatively simple structures like this meniscus. 53 00:03:13,912 --> 00:03:17,561 Bioprinted bladders have also been successfully implanted, 54 00:03:17,561 --> 00:03:23,091 and printed tissue has promoted facial nerve regeneration in rats. 55 00:03:23,091 --> 00:03:26,942 Researchers have created lung tissue, skin, and cartilage, 56 00:03:26,942 --> 00:03:33,672 as well as miniature, semi-functional versions of kidneys, livers, and hearts. 57 00:03:33,672 --> 00:03:37,024 However, replicating the complex biochemical environment 58 00:03:37,024 --> 00:03:39,954 of a major organ is a steep challenge. 59 00:03:39,954 --> 00:03:42,984 Extrusion-based bioprinting may destroy 60 00:03:42,984 --> 00:03:47,754 a significant percentage of cells in the ink if the nozzle is too small, 61 00:03:47,754 --> 00:03:50,893 or if the printing pressure is too high. 62 00:03:50,893 --> 00:03:52,863 One of the most formidable challenges 63 00:03:52,863 --> 00:03:58,703 is how to supply oxygen and nutrients to all the cells in a full-size organ. 64 00:03:58,703 --> 00:04:01,390 That’s why the greatest successes so far 65 00:04:01,390 --> 00:04:04,420 have been with structures that are flat or hollow— 66 00:04:04,420 --> 00:04:06,920 and why researchers are busy developing ways 67 00:04:06,920 --> 00:04:11,320 to incorporate blood vessels into bioprinted tissue. 68 00:04:11,320 --> 00:04:13,778 There’s tremendous potential to use bioprinting 69 00:04:13,778 --> 00:04:16,178 to save lives and advance our understanding 70 00:04:16,178 --> 00:04:19,208 of how our organs function in the first place. 71 00:04:19,208 --> 00:04:23,358 And the technology opens up a dizzying array of possibilities, 72 00:04:23,358 --> 00:04:27,258 such as printing tissues with embedded electronics. 73 00:04:27,258 --> 00:04:31,558 Could we one day engineer organs that exceed current human capability, 74 00:04:31,558 --> 00:04:35,925 or give ourselves features like unburnable skin? 75 00:04:35,925 --> 00:04:42,242 How long might we extend human life by printing and replacing our organs? 76 00:04:42,242 --> 00:04:44,754 And exactly who—and what— 77 00:04:44,754 --> 00:04:49,054 will have access to this technology and its incredible output?