Five Common Misunderstandings Every gap in medical knowledge is an opportunity for you to discover new and better cures. The larger the gap, the bigger the opportunity. The worst obstacles to understanding are plausible misinterpretations. Simple lack of knowledge is rarely a big problem, especially once scientists know what new facts they need most. When everybody is looking for the wrong information, however, there can't be much progress. Here are five big mistakes, that hold back medical progress: Atherosclerosis is caused by cholesterol sticking to the inside walls of arteries. Cancer is caused by cells growing too fast. Autoimmune diseases result from cells not being able to distinguish "self". Undifferentiated stem cells are needed and sufficient to regenerate arms or legs. Aging is simply a result of the body wearing out by cumulative damage. As you have learned about atherosclerosis, the blockage is swelling of the artery walls themselves (not just stuck to it), and only a small fraction of this material is cholesterol. Mostly, the blockage consists of macrophages and smooth muscle cells. In atherosclerosis, the invading macrophages accumulate vacuoles and are called "foam cells". Their most important abnormalities is that they don't leave. Cholesterol has something to do with this. Microscopic blobs of cholesterol accumulate among the swelling, and people and animals that have unusually large amounts of cholesterol in their bodies develop severe atherosclerosis at relatively young ages. Incidentally, that business about "bad" cholesterol and "good" cholesterol has nothing to do with differences in the cholesterol molecules themselves. Instead, there are special proteins whose function is to carry cholesterol, to bind many molecules of cholesterol and make them soluble. For some reason that I haven't been able to find out, having lots of one of these kinds of cholesterol-carrying proteins is correlated with less atherosclerosis, and the other is correlated with more, earlier and worse atherosclerosis. Knowing all this, can you suggest how to cure or avoid atherosclerosis? Stimulate the foam cells to crawl into the blood? Induce apoptosis in macrophages? Induce active rearrangement of smooth muscle cells? Keep on thinking! You are much closer to inventing a cure than you would be without the information above. .