Recently, I was flipping through the channels on television looking for something interesting to watch. I stumbled across a program titled, “Explorer, How to Build a Beating Heart” and in light of this class, I decided to watch.
The show begins by showcasing a woman named Samantha who was born with a defective heart and is on the waiting list just like thousands of other Americans. Because only 2,500 transplants are performed each year with roughly 100,000 people on the waiting list, she will likely die waiting unless something changes that allows science to grow her a new heart. From there, the show began describing the science behind regenerative medicine. According to the doctors, the goal of regenerative medicine is to potentially grow organs and body parts with the hope of transplanting them to human beings in need or altering their own bodies in such a way that they can grow back tissue and entire limbs themselves. For those in need, this science is in great spirit but for those whom own and run businesses based on the development of hardware of artificial parts, this scientific possibility unfortunately threatens their business and well being.
The first experiments done with regeneration according to the show were performed with rat hearts. A dead rat’s heart was used and put into a decellularization machine. The decellularization machine removes all living cells so that when the organ is implanted there are no remaining donor cells that could potentially be rejected. The next step is to isolate the cells to repopulate the remaining scaffold for the organ in hopes of regenerating the organ. The organ is then placed into a bioreactor that simulates the environment of a body so that the cells implanted will repopulate the organ with living tissue. After the cells are repopulated and the heart is shocked the scientists wait to see if the rat heart will beat. The heart, indeed, does begin to beat on its own. The success of this experiment obviously causes the scientists to have the desire to try the exact same experiment using a human heart to see if they can regenerate it in the same way. They do try this and it is showcased at the end of the show, so back to this later.
The next segment features the importance of being able to keep organs alive outside of the body. If we can grow organs successfully, we must be able to keep them alive long enough to be transplanted successfully. Interestingly, most of the research done on regenerative medicine occurs in rehabilitation hospitals belonging to the military when they are working on injured soldiers coming back from Iraq and Afghanistan. The scientists have plenty of subjects because modern warfare has allowed for the development of much more sophisticated equipment that solders are now outfitted with so when 50 years ago a particular injury would have likely caused a soldier to die, today they live as a result of their protective equipment. It is because of this, many more soldiers are returning home with injuries to rehabilitation hospitals which gives them many subjects to study. Additionally, the defense department is the largest contributor to regenerative medicine research.
The most successful regenerative medical project the scientists have discovered is the regeneration of human ears. First an engineer creates a scaffold for an ear. From there, they place an extracellular matrix on the scaffolding for the new cells to adhere to and then attach them to the backs of mice to see the cells repopulate. The science of developing lab grown human ears has been successful because ears are easier to regenerate because they do not require such a complex network of blood vessels to keep them alive and supplied. The biggest problem they face after development? Attaching them to the skin. Lab grown skin has been grown in labs for many years and is relatively easy to do, but it is a slow process and for burn victims, they need skin that will adhere and grow very quickly before the scarring has a chance to take over.
A scientist featured on the show has developed an experimental spray gun that is loaded with someone’s own stem cells and then the cells are sprayed on the burn or area of injury. The advantage of the gun is that it effectively covers burns very quickly and heals them in enough time to prevent typical burn scarring. Amazingly, a man featured on the show who was burned in an accident with bonfire was the first person used with the gun. He had second degree burns on his side, arm, neck and face. Almost immediately, they harvested stem cells from his skin, loaded the gun and sprayed the fresh burns. He now looks like he was never burned and you would have never known that he had second degree burns on almost half of his body.
The next segment elaborates on the cellular matrix and how it works. As the scientists have begun to study the ECM (extra cellular matrix) in more depth to figure out how and why these stem cells take to the ECM so well. The ECM combined with a patient’s own stem cells is more promising than using embryonic stem cells because a patient’s body won’t reject their own stem cells, but they will reject embryonic stem cells. Additionally, there is an added complication with the development of solid organs. There have been a few successful experiements with the ECM done using muscle tissue, ears, and even a human bladder, but developing a more complicated, solid organ is a challenge because it is more difficult to recreate the blood vessels needed to fill the organ. Believe it or not, they are using cotton candy to mimic the blood vessels of the human body and creating molds out of that in hopes of some day using the cotton candy blood vessel molds to create solid organs.
Following the promise of possibly regenerating or growing organs outside of the body the following question is raised: Why do humans not regenerate entirely? Our fingernails, the lining of our intestines regenerate, but not whole fingers, limbs or organs. Why is this? To look for possible answers we look to salamanders who have the ability to regenerate and regrow entire limbs. So what is the difference between us and salamanders that makes it so we cannot regenerate in the same way? We scar while salamanders do not. We have evolved as human beings to scar and scarring is what keeps us alive after a traumatic injury. We might not be able to get our limb back, but we are alive to see tomorrow. If humans could scar less, then maybe we could regenerate better.
Some very successful experiments are featured with regeneration using the ECM of a pig bladder to grow back digits in their entirety. A guy named Lee got the tip of his finger cut off by accident in the propellers of a model plane. He went to a surgeon who, of course, told him that nothing could be done to restore his lost finger tip. Through a fortunate series of events, Lee was chosen to use the ECM from a pig bladder to grow his finger back. In 5 treatments of sprinking the powdered ECM on his wounded finger his finger was completely regenerated, nail and all. The success of this caused the scientists to take a closer look at the ECM. How, exactly, does the ECM work to do this. It turns out, the ECM sends signals to our cells to regenerate instead of scarring so stem cells are set to grow new tissue. Briefly, and also interestingly, at the end of this segment they mention the potential ethical problems of the development of this type of technology. If we can grow an entire limb or organ, then eventually we should have the ability to grow an entire human being in the lab. Without stating the ethical problems explicity (since they are completely obvious here), the posed question leaves the audience including me wondering.
The end of the show goes back to the same experiment with a rat heart showed at the beginning and is now tried on a donated human heart. Just like the rat heart, the heart is harvested and all the cells are removed only leaving the scaffolding. Human stem cells are added to the heart and the heart is placed in a bioreactor so that the stem cells will populate the scaffold and grow into new tissue. After the heart is regrown, the scientists attempt to pump the heart to “teach” the cells to expand and contract and behave like heart cells. Unfortunately, unlike the rat heart, the regenerated human heart does not beat on its own and this is where the similarities between the rat heart end.
I wanted to share this show with the class and I hope I did a sufficient job in describing the knowledge and research the show featured. It was very interesting and got me thinking a lot about the speakers we’ve listened to and the readings we have discussed thus far in class.