 Oftentimes, when we learn biology, we ask, who cares? And argue that what we learn from the textbook doesn't apply to our lives, or the real world. But the truth is, it does matter. And here is why. Do you think we could fix a broken machine if we didn't know how it worked? No, right? Well, the same goes for biology. In order to treat disease, we need to understand biology. This is why scientists are constantly doing research to better understand how our bodies work, while also investigating lots of exciting new questions. New discoveries can translate into very practical improvements for all of us, such as new medicines or guidelines for avoiding cancer risks. And some of the smallest things we learn about in biology class are often the most important to maintain our health. And they are being researched by these scientists all over the world. For instance, a vesicle. We learn about vesicles as these small, little organelles inside of cells that just transport things around, like vehicles. However, right now at the University of Pennsylvania, scientists are intently studying a particular type of vesicle called an exosome. An exosome is a type of vesicle which leaves the cell. They circulate in our bloodstream all the time. And there are two big ideas about exosomes that scientists at UPenn are focusing on. One, using exosomes as a targeted drug delivery system. And two, using exosomes to better predict patient response to drug therapy. Let's start with number one. What exactly is targeted drug therapy? Let's look at a common drug, such as ibuprofen, or Advil. This is a typical, non-targeted therapy which helps relieve pain. When we take an ibuprofen pill, the drug spreads out over the whole body. This means it is not as strong as it could be at the painful area. And also, because the whole body is being treated, there might be unwanted side effects. Targeted drug therapy means that the medicine goes directly and only to the body tissue that is in trouble. To transport the drug to the target, artificial vesicles can be made that can specifically recognize little receptors on the outer surface of cells that make up the painful tissue. The problem is our immune system recognizes these artificial vesicles as intruders, and it tries to eliminate them. So, scientists and doctors want to find a way to deliver drugs through naturally made exosomes, which should not be eliminated by the immune system. Scientists at UPenn are trying to use these tiny exosomes to deliver treatments to help with cartilage damage in our joints, which is irreversible, causes unbearable pain, and is seen in about 50 million people in the United States. Now on to the second big idea. Remember that cancer cells divide uncontrollably to form a tumor which prevents the tissue from functioning properly. Pieces of this tumor can sometimes break away and invade healthy tissues elsewhere in the body. These are metastatic tumors. One team of researchers at UPenn is looking at metastatic melanomas, skin cancer cells that are spreading. They found that these skin cancer cells release exosomes with a protein on their surface which stops our immune cells from recognizing and killing the cancer cells. So the cancer cells can continue to spread without anything standing in their way. And because the patients with metastatic melanoma have more exosomes with this special protein circulating in their blood, we can take a blood sample to detect the exosomes and make a quick and early diagnosis of the disease. Detecting this exosome can also indicate whether a patient will respond to some existing therapies. Armed with this information, we can now better predict whether a certain therapy might work for a patient. So who cares about understanding all of the details of how our body works? According to the little tiny organelles that we can't even see without really powerful microscopes, well, these guys care. They care about understanding the smallest structures in our bodies with the goal of inventing new ways to treat disease.