Antarctic Bear Introduction:According to relevant data, as of June 10, 2022, there were 106,075 men, women and children on the waiting list for organ transplants in the United States. However, living donors only provide about 6,000 organs per year on average, and about 8,000 deceased donors provide an average of 3.5 organs each year, which is clearly not enough to meet the demand for transplants. If doctors could print a kidney directly from a patient’s cells, instead of finding a matching donor, wouldn’t that fundamentally solve the problem?
△In Wake Forest Regenerative Medicine Institute, a bladder scaffold was seeded with cellsThis type of regenerationmedicineis in development, and the driving force behind this innovation is “real human needs”. “Some people have experienced catastrophic health events, their organs are not of high quality enough to be donated, or they are not on the organ donor list in the first place, so finding a good match is very difficult,” Lewis said. In 2006, Dr. Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine, and his colleagues grew human bladders by hand in the lab and implanted a complex organ into the human body for the first time — saving three the lives of the children they implanted in their bladders.
According to the U.S. Health Resources and Services Administration, 17 people die every day while waiting for an organ transplant, and one person is killed every 9 minutes. Put on a waiting list. In 2021, more than 90 percent of people on the transplant list will need a kidney. Lewis said: “There are about 1 million people around the world who need a kidney, have end-stage renal failure and have to go on dialysis. Once a patient goes on dialysis, they basically have only five years to live, and every year Mortality increases by 15%. Dialysis is very tough on the patient’s body. So that’s really what motivated us to take on the grand challenge of printing organs.”< strong>Principles of 3D Printing OrgansTo begin the process of bioprinting organs, doctors usually start with a patient’s own cells. They take a small needle biopsy of an organ, or do a minimally invasivesurgery to remove a small piece of tissue, less than half the size of a postage stamp. By taking this small piece of tissue, cells can be separated and grown and expanded in vitro. This growth occurs inside a sterile incubator or bioreactor, a pressurized stainless steel vessel that helps cells retain nutrients. Doctors “feed” every 24 hours because cells have their own metabolism. Each cell type has a different medium, and the incubator or bioreactor is like an oven-like device that mimics the body’s internal temperature and oxygen. The cells are then mixed with the gel, which is like a glue, every organ in your body has cells and glue that holds it together, this is also known as the ‘extracellular matrix’ ‘. This is a printable mixture of living cells, water-rich molecules called hydrogels, and mediators and growth factors that help cells continue to proliferate and differentiate. The hydrogel mimics the human body’s extracellular matrix, which contains substances including proteins, collagen and hyaluronic acid. The acellular sample portion of the glue can be made in the laboratory, and the biological material used must be non-toxic, biodegradable and biocompatible to avoid negative immune responses. Collagen and gelatin are the two most common biomaterials used to bioprint tissues or organs. The process of printing organsThe doctor will place the bioink (depending on what they want to print) cell types) into a print chamber, and the ink is squeezed out using a print head and nozzle, building up the material layer by layer. Tissues with personalized properties can be created by programming the printer with imaging data from a patient’s X-rays or scans. With a color printer, there are several different ink cartridges, each of which prints a different color, and then you come up with your (final) color. The same goes for bioprinting; you just use cells instead of traditional inks. How long the printing process takes depends on several factors, including the organ or tissue being printed, the fineness of the resolution and the number of print heads required. But it usually lasts a few hours. The time from biopsy to implantation is approximately four to six weeks.
△A 3D printer seeded different types of cells onto a kidney scaffold
The ultimate challenge is to “get the organs to actually function as they should”, just like harvesting an organ from a donor, the 3D printed organ must be immediately placed into a bioreactor and perfused , otherwise the cell will die. A perfusion organ is the supply of fluid, usually blood or a blood substitute, to it through the circulation ofvasculatureor other channels. Depending on the complexity of the organ, it is sometimes necessary to further mature the tissue in the bioreactor, or to drive connections further. In order for the printed organ to truly function in the body like a human organ, some plumbing issues and challenges must be completed. Honestly, this has not been fully resolved. OneOnce the bioprinted organ is implanted in a patient, it will naturally degrade over time, which is no problem because it is designed that way. “As the glue gradually dissolves, the cells sense that they no longer have a firm footing. So the cells begin to create their own bridges, creating their own glue.”< /span>How many more years will it take and how much will it cost?Lewis and Atala for fully functional bioprinting Conservative estimates of the number of years remaining before organs can be implanted in humans. Lewis said, “The field is growing fast, but I think we’re talking about a decade or more, even with all the tremendous progress that’s been made.”Atala said:” I learned years ago never to predict because you can always There are too many factors in terms of regulations). Our interest is in making sure the technology is safe for the patient, which is paramount.”Whenever bioprinted organs become an available option, Affordability for patients and their caregivers should not be an issue. Atala said: “The costs associated with organ failure are very high. Just to keep a patient on dialysis costs more than $250,000 a year. So creating an organ that can be implanted in a patient requires Much cheaper.”According to research published by the American Academy of Nephrology, the average kidney transplant cost in 2020 is $442,500 — while 3D printers retail for around a few thousand dollars and can range up to $10 million dollars, depending on its complexity. But even with low-cost printers, the expensive parts of bioprinting can include maintaining cell banks for patients, culturing cells and safely handling biological materials. Some of the major costs of organ transplants right now are “getting the organ from the donor, shipping costs, then of course the surgery the recipient goes through, and then all the care and monitoring.” Even bioprinting, where Some costs are still unavoidable. “
Harvard develops 3D bioprinted heart technology that accompanies maternal growth, which is expected to solve the dilemma of “hard to find”
On June 12, 2022, the Antarctic bear was informed that a researcher from Harvard’s Wyss Institute for Bionic Engineering and Harvard’s School of Engineering and Applied Sciences (SEAS) Jennifer Lewis’ team has collaborated to develop a new set of heart engineering techniques that mimics the complex arrangement of cardiac contractile elements while producing tissue thick enough for regenerative heart therapy.
△3D bioprinting process
The development of thin slices of cardiac tissue with a complex and varied arrangement similar to actual human myocardium will hopefully pave the way for 3D printed cardiac tissue substitutes.
To test the contractile characteristics of the printed heart structures, the researchers also printed “large filaments” connecting two large posts and measured the contractile force produced by the filaments and contraction rate increased over 7 days, suggesting that cardiac filaments are capable of maturing into true muscle-like filaments.
△3D bioprinted heart cells
In the future, with this technology, it can be used to generate more models of physiological diseases and create highly structured myocardial patches that, like Lego blocks, can be matched And used to replace patient-specific scars after a heart attack.
Similarly, they can be customized to patch patient-specific ‘holes’ in the hearts of newborns with congenital heart defects, and the patches can accompany the child development without having to followchange as the child grows.
Additional advances in 3D bioprinted cardiac tissue
As early as 2017, a research team at the Federal Institute of Technology in Zurich used 3D printing technology to create an artificial silicone heart that can beat like an organ in the human body, but the test results at the time showed that it could only be used for 30 times. to 45 minutes.
△Picture from: ETH Zürich
△Picture from: Wyss Institute
A research team from the Chinese Academy of Sciences and Tsinghua University creatively transformed a six-axis robot into a biological 3D printer–a six-axis robotic biological 3D printer, realizing 360° all-round and any angle Cell printing; and developed an oil bath cell printing system to better maintain the natural function of cells after printing. Combining a self-designed bioreactor and an iterative printing culture strategy, the bioprinting system is able to generate vascularized, contractile, and long-lived cardiac tissue, providing a promising solution for the in vitro fabrication of complex organs.
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