Look at your finger tips. You have hard nails, unique finger prints, and nerve endings that can read brail. All these began from a single cell that divided many times. How did one cell become so many different kinds of cell tissue with so many different shapes? How did it decide that your fingers were going to stop growing at different lengths but that your fingernails would continue to grow? How did some cells become ridges and some cells become valleys and line up in swirls on your finger tips? How do cells know if they’re a knee bone or an eyebrow? How did you get to be you?
All tissue in our body and our eleven primary body systems come from stem cells. That’s why stem cells are in the news today. Stem cells are the only cells that make more of themselves. When needed, stems cells also make intermediate cells (TACs), which make fully differentiated cells. How this happens is poorly understood, but it’s being vigorously studied. If we could figure out how the body makes the different kinds of intermediate cells, then maybe we could grow any tissue we want.
The differentiation process has an ingenious way of turning genes on and off in the DNA string, so that the daughter cell can’t make certain proteins. This transforms the cell into a different kind of cell. This can be done for certain genes in the laboratory, but I don’t know from my reading if anyone knows for sure how it is done in the body. We understand the process in general, but with tens of thousands of genes to turn on and off in trillions of cells, which cells decide to turn off which genes and how do they do that in the right cell at the right time? Some scientists dedicate their entire lives to understanding just one gene. The communication that exists between cells is absolutely phenomenal.
Gene editing is a little different. To date, China has genetically engineered at least 86 cancer and HIV patients. This involves taking immune cells from patients, changing critical genes in the DNA using CRISPR/Cas9 technology, and transfusing the cells back into the body. The difference is between replacing broken genes and blocking genes from being used. In either case, we’re messing with some very powerful machinery that we don’t fully understand.