Overview of Organisms
So what are organisms? By definition, an organism is anything that does seven things: move, reproduce, respond, need nutrition, excrete, make energy, and grow. Without all of these characteristics, an object cannot be considered an organism. Organisms come from an extremely large range of sizes, from the smallest bacteria, to the largest blue whale. Anything that meets all the criteria for life can be considered as an organism.
The basic unit of any organism is the cell. The cell contains a nucleus, where deoxyribonucleic acid (DNA), the blueprints for the entire cell, is stored. The DNA is copied to ribonucleic acid ( RNA) and transformed to proteins. This DNA to RNA to protein governs the entire workings of the each cell.
Cancer. Two syllables that stand for one deadly disease. Cancer starts with one cell. One cell makes a mistake when replicating DNA. This mistake causes a cell to divide rapidly, drawing nutrients away from healthy cells, and sucking all the nutrients into these malevolent cells, slowly starving and destroying the organism from the inside out. Cancer can affect any part of the body, including the brain, the heart, and the blood. Cancer is feared because there are only a few cures for only a few types of the disease. Cancer starts as a small cell, undetectable by any viewing system known. The cancer only becomes noticeable when it has replicated many times, and by then, it is too late.
Cancer is one of the most dangerous diseases because there are no symptoms until it has grown tremendously. To most effectively cure cancer, we must find a way to spot cancer in its earliest stages. Before it grows out of control. In the summer of 2006, Professor Shuming Nie found a way to spot cancer. He created designer nanoparticles called quantum dots, which shine light from inside the body. Next, he created a molecular container that clung to cancer cells like superglue. Because the quantum dots and the container were so unlike, the quantum dots wouldn’t stay in the container.
Professor Nie then created a substance that had two sides: one that stuck to the quantum dots and one that stuck to the container. After he had achieved this, he tested it on mice with injected human prostate cancer cells. These quantum dots traveled around the body, then clumped around the human prostate cancer cells. When viewed, the cells glowed with bright orange light. Unfortunately, there are some limitations. The quantum dots work by adhering themselves to markers on cancer cells. Prostate cancer has one distinguishing marker, but not all cancers do. Still, many types of cancers have a combination of these markers, which researchers can use to identify the type of cancer. Also, visible light is not easy to see through tissue and bone. A solution to that is to use a type of light that is not affected by bone and tissue, such as infrared. If these limitations are overcome, then we may be able to see cancer when it is just a single cell.
But once we see cancer, can we stop it? Today’s treatments involve carpet-bombing the patient with rays or drugs. While it does help stop cancer, it also attacks the patient. Can we find a way to target the drugs in a specific area?
Cancer has certain receptors on its surface that distinguishes it from other cells. Using these receptors, we can distinguish and connect objects to the cancer cells alone. Taking this one step farther, we can use these receptors to latch cancer drugs onto the cells. Liposomes are nanospheres that can be filled up with drugs to deliver them to a cell. If we attach the appropriate molecules that match a cancer cell receptor, the liposomes will only connect with the cancer cells. The cancer cells will swallow the liposomes through endocytosis, and the drugs will be released, destroying the cancer cells. Still, liposomes will be attacked by our immune system, the system that destroys malignant objects in our body. In order for the liposomes to work well, we will have to stop our immune system from recognizing these nanospheres as enemies.
When your car breaks down, you either fix what’s broken, or replace it. If you get sick (your body breaks down), you go to the doctor. When you get medical treatment, you usually fix what’s broken. If your condition is severe, you will need to get a transplant (replacement). Unfortunately, organs aren’t very easy to get, so there is a long waiting list for replacement organs. About 15% of the candidates for liver or heart transplants die while on the waiting list. Today, organs are only useful when they have been living inside a human body for many years. Is there a way to grow these organs?
If we are to create organs, we must first decide on the shape and size, which can be customized. Next, we produce a scaffold for the organ, a structure on which it can grow on. Lastly, we put cells into the scaffold to let the organ grow. One of the hard parts is creating the scaffold. The scaffold needs to meet certain criteria to work, all at the same time. The scaffold needs to allow cells to travel through them, to provide nourishment, and to disappear when not needed.
Sam Stupp has built a scaffold that meets all three requirements. Stupp created a special molecule to build this scaffold. The molecule has a special property: one end is attracted to water (hydrophilic), and the other is repelled against it (hydrophobic). Other substances built like this molecule are soap and phospholipids, the molecule you find in cell membranes. This kind of molecule will form a cylinder if enough of these molecules are put in a liquid. The head of the molecule will face outside, protecting the tail, the hydrophobic part, from the outside. In the experiment, he decided to work on growing nerve tissue. On the head portion of the molecule, Stupp attached a protein that would promote nerve tissue growth. Stupp let the scaffold assemble themselves and added stem cells, cells that do not have a specific job, and can therefore specialize into many different types of cells. Stupp found that his scaffold helped the cells survive, and actually created living neurons instead of scar tissue, which will not send signals.