This blog post explores why the human body cannot fully regenerate and whether animal testing holds potential to overcome these limitations.
Humans cannot restore severed fingers or noses lost in accidents to their original form. Such physical loss is not merely cosmetic; it leads to functional impairment, causing significant inconvenience in daily life. Furthermore, this loss often results in emotional trauma, leaving many experiencing social isolation or depression. For those who have lost a body part, a method to restore it is desperately needed. However, the reality is that current medical technology lacks a perfect solution for this.
Many people suffering from incurable diseases tragically die because they cannot receive the necessary organ transplants in time. At present, there is no adequate method to resolve this. The organ transplant waiting list grows longer each year, forcing families and patients to spend their time in despair and anxiety. The medical community is striving to advance artificial organs and bioprinting technology, but numerous technical and ethical issues remain before these can be widely applied. Yet chemical engineers are working to bring hope to these individuals.
Charles Vacanti, Director of the MIT Medical Center, and many chemical engineers are conducting research to create human ears by inserting bovine cartilage cells into mice. There is currently no known method to repair the cartilage portion of the ear when it is deformed, whether congenitally or acquired. This is why Charles Vacanti and many others are attempting to grow cells shaped like an ear on the back of a mouse. This research is considered a significant breakthrough that could profoundly impact future medical technology, going beyond mere scientific curiosity. The reason is that if this research succeeds, it could open the possibility of repairing other parts of the human body or organs in a similar manner. These mice are called Vacanti mice.
In the process of creating ears, engineers use nude mice. If regular mice were used, injecting bovine cartilage cells would trigger a rejection response. In contrast, nude mice are not only hairless due to a mutation but also possess a very weak immune system. This weak immune system does not reject externally injected cells, playing a crucial role in the success of this experiment. These nude mice provide a space where bovine cartilage cells can grow well and also serve as an energy source to aid their growth.
Let me explain the experimental process in detail. First, a scaffold is inserted into the mouse to help bovine cartilage cells grow into an ear shape. A crucial point is that this scaffold must be placed between the mouse’s skin and muscle layer. This scaffold is made of a material similar to the suture thread used in surgery, so it degrades into water and carbon dioxide after a certain period inside the body. Furthermore, the structure is formed like a wire mesh, with 97% of its interior filled with air. This allows the bovine cartilage cells to grow within the empty spaces previously occupied by air. After approximately three months, the mouse’s blood vessels extend to the area containing the bovine cartilage cells, supplying nutrients. The cells differentiate within the mesh. Once the cells have fully formed into the shape of a human ear, the mesh completely biodegrades.
This experiment has not yet been performed on humans. Since bovine cells are still being used, a method for transplanting them into humans without immune rejection has not yet been found. Researchers also emphasize that thorough safety and efficacy verification is necessary before applying the experiment to humans. This is because it involves a highly significant ethical issue in the field of biotechnology. However, engineers anticipate that experiments using human cells will be possible in the not-too-distant future.
In fact, such technological advancements hold the potential to revolutionize our lives. If repairing damaged organs or body parts becomes possible, it could significantly contribute not only to extending human lifespan but also to improving quality of life. Yet ethical barriers remain. One might worry that when this technology becomes commercialized, animals could be treated merely as tools for producing organs. Indeed, creating internal organs requires various animals, not just simple parts like ears. Nevertheless, scientists and engineers are conducting research while carefully considering the ethical issues of animal testing. This is to ensure a balance between scientific progress and ethical responsibility. Ethical deliberation regarding animal testing continues steadily, and without such sacrifices, modern biotechnology would not have reached its current position. Of course, we must always be grateful to these animals, but today, chemical and biological engineers worldwide continue their research for the countless people still suffering near us.
