Introduction to Regenerative Medicine
The body works as a complete system, where all its parts have different functions that support each other. In many ways, we can compare the function of certain organs to machines: the heart is like a pump that pumps blood, the brain is like a computer that processes thought. But, unlike a machine, the body has a fantastic ability to adapt and heal!
Regenerative medicine works with the body' natural healing processes, so when an injury occurs that is beyond what the body can heal, doctors can intervene and help the healing occur faster or use special materials from the laboratory to regrow tissue.
The injuries in question have to do with extensive tissue damage like broken bones, severe burns, heart attacks (damaged heart muscle) or spinal cord injuries. Some of these injuries will take months to heal. Sadly, some injuries will not heal at all.
Where some individuals will get new treatments that utilize regenerative medicine that help them heal in weeks, not months. Other individuals will get new treatments that cure them forever, improving and even saving their lives.
Where the body’s healing ends, regenerative medicine takes over!
Our body has a fantastic ability to heal itself! But some injuries are more than the body can handle. Doctors and scientists are working on regenerative medicine to help speed the body's natural healing ability.
Injuries and Healing
When areas of tissue in the body are damaged or destroyed, the body tries to replace them with new tissue by producing cells capable of creating new tissue.
When a tissue like bone is broken, both its cells and its blood vessels may be injured. The body is prepared to heal minor injuries like these, so when trauma occurs the body works to stop any blood loss by clotting. Then the body starts producing new cells to replace the damaged ones. These new cells are produced in several places in the body, the main one being the marrow in the center of the bone. They travel through the body to the damaged site and become new tissue. The body also builds new thin blood vessels, called capillaries, to bring nutrients and oxygen to the new cells.
When the damage is too extensive and there is a big gap of missing or dead tissue where no capillaries survive, new cells cannot fill the area because there is no blood reaching them with nutrients and oxygen.
Some tissues are easier to heal than other tissues in the body. Those that cannot heal as well form scars in the places where they were mended. The scar tissue is a weaker and more disorganized tissue than the original, healthy tissue.
Cells, Tissues, and Organs
All living things are made of cells. Humans, plants, birds, and bacteria are all made of cells.
One Cell or Many Millions – The Complexity of Life
Cells have existed for millions of years. A cell is the basic unit of life, which means that all living things are made of cells.
Some life forms, like bacteria, are only one cell and others, like humans, are made of millions of cells. Single-cell organisms, like bacteria, are very efficient organisms. Some bacteria live in extreme environments where no human could go without special equipment. In more complex organisms, different groups of cells work together to do complex functions, such as protecting the body from the outside environment or allowing the organism to be able to move and look for food. With increased complexity comes an increased need for energy and an increased capacity to interact with the world!
Cells can work together!
Millions of years ago, life consisted mostly of one-celled organisms, but over time a myriad of bigger and more complex organisms emerged. One of the most interesting things scientists have found is that at some point some cells developed the ability to swallow other cells! Some scientists think this was the beginning of eukaryotic cells.
At some point, some cells started to stick together like glue, forming multicellular organisms (organisms with more than one cell). When cells started to work together, cells were able to start focusing on different tasks:
- Some swallowing cells took over the process of eating for their neighbors, so their neighbors could have time and energy to do other things.
- The outer cells became "skin" cells to help protect the inner cells which became "eating cells."
- Some cells became really good at moving around in a group of cells and sniffing out bad or dead cells to remove them before they harmed their neighbors.
This kind of cell cooperation happens all over!
For example, in your immune system, you have special cells called B and T cells that travel through the body and talk to each other to determine whether a newfound particle is good or bad.
Your neurons carry messages from all over the body— signals to the brain from all over your body and from your brain out to all parts of your body.
Cells and Tissues
In complex organisms, like a human being, you can find many kinds of cells, such as muscle cells, bone cells, intestinal cells and immune cells! Each kind of cell works together to form a specific tissue; for example, there are a few different kinds of skin cells that work together to form the skin.
A tissue is made when of one or more types of cells, group together. These cells are held together by the extracellular matrix which is sort of the glue that holds everything together. Blood vessels bring oxygen and nutrients that the cells need to live, into the tissue.
Stem cells are special cells that are able to develop into many different types of cells. Stem cells can divide again and again, renewing other cells in the body of a person or animal. They serve as an internal repair system for the body, replacing damaged or dying cells with healthy new cells.
There are two main types of stem cells: embryonic stem cells and non-embryonic stem cells. Embryonic stem cells are found in embryos- the small ball of cells created shortly after an egg is fertilized. Non-embryonic stem cells (also called "somatic" or "adult" stem cells) are found throughout the body in various tissues. When a stem cell divides it creates two new cells. Each cell that is created may remain a stem cell or may become another type of cell that has a distinct function, such as a skin, brain, lung, muscle, or even a red blood cell. The process of a stem cell turning into a specific type of cell is known as differentiation.
In regenerative medicine, stem cells play an important role. Stem cells can be used to treat illnesses or injuries because of their unique ability to differentiate. For example, if a person has a disease, this person's stem cells could be collected. Then, in a laboratory, these cells can be made to differentiate into a specific type of cell that the person needs to help them. The cells could then be put back into the individual’s body to help treat their disease.
Regenerative medicine provides an artificial support structure – a scaffold – to allow the new cells and capillaries to settle and make new tissue.
The scaffold is structurally similar to the tissue that it is trying to help so the body will recognize it. It also must be strong enough to provide support but naturally degradable so that it can eventually be entirely replaced by healthy, new tissue.
In the future, regenerative medicine could potentially be used to find cures for problems like spinal cord injuries, diabetes, diseases like Parkinson's, and replacing and entirely healing bones and organs like the heart.