Regenerative Medicine
The Future of Healing
The Process
After amputation, stem cells accumulate at the injury site in a structure called the blastema. It is being researched how signals from the injury site cause the stem cells to form the blastema and start dividing to rebuild the missing part. Stem cells can eithier be a single type of stem cell in the blastema that can differentiate into many different types of tissues (called pluripotent stem cells) or they can be separate sets of stem cells responsible for making each of the different tissues needed to make up the new body part. Animals such as planarians use multipotent stem cells to regenerate from just a head or a tail. The presence of multipotent stem cells allows this animal to regenerate many different body parts since the stem cells are able to grow into skin, muscle, or even bone cells. On the other hand, animals such as frogs and lizards use a different type of stem cell called an adult stem cell to regenerate. Adult stem cells can only regenerate the same type of tissue or organ as it originally came from. For example, when a lizard looses its tail in the common act of self decense, stem cells in the spinal cord migrate into the regrowing tail and differentiate into several cell types, including muscle and cartilage. The lizards ability to dedifferentiate cells is why they are able to just drop their tail and regrow one a couple of weeks later.
Since humans can do not have the ability to regenerate completely, scientists have researched ways to mirror the regenerative properties of these animals in order to better the lives of those in need. The process often begins with a scientist building a scaffold from artificial materials such as plastic or even using an existing scaffold from an organ by taking all the cells out and leaving just the remaining protein collagen. Once scaffolds are created, cells induced with a "cocktail" of growth factors can be introduced to the cell-less organ. If the environment is right, a viable tissue develops. In some cases, the cells, scaffolds, and growth factors are all mixed together at once, allowing the tissue to “self-assemble.” This process has been used to bioengineer kidney, lung, and even heart tissue. Regenerative medicine is a relatively new topic in science so, even though many important discoveries have been made, we are still a long way off from most of them being used in human practice. Supplemental bladders, small arteries, skin grafts, cartilage, and even a full trachea have been implanted in patients, but the procedures are still experimental and expensive. So, even though artificial hearts, lungs, and livers have been recreated in labs all over, it will still be a while until we see people walking around with an artificial heart after a severe heart attack.
The Growing Future
Regenerative medicine has been around since the sixteenth century when tissue graffing by surgeons, Cosmas and Damian inspired the painting of the “Transplantation of a leg by Saints Cosmas and Damian, assisted by angels” (Stuttgart, Germany) and made a huge impact in the medicine minds of scientists all over Europe but it was not untill fairly recently that regenerative medicine has been intently researched. Many discoveries have been made, including the discovery of stem cells, and in the upcoming years, it is expected that regenerative medicine will be an important factor in everyone's life. There are many goals that researchers and scientists are working on in order to make a huge impact. Almost every organ in the body can be recreated in a lab but the challenge to scientists all over the world is making the experiment easily recreated and safe enough to be implanted into a human recipient. Some day, surgeons will be able to bring home an amputee with a fully functional leg or relieve a diabetic from daily insulin injections by replacing the islets within the pancreas.
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Watch this video for a some information on animal regeneration