The way embryonic stems cells are collected is by fertilizing an egg and then letting it sit for 3-5 days. Within these few days an embryo is formed and the stem cells are ready to be extracted. In order to extract the stem cells it kills the embryo which is a big ethical problem. I am concerned about this because there is a more ethical way to get stem cells.
Adult stem cells are collected from the same person that needs these types of cells. By using these types of stem cells the patient is less likely to reject the stem cells and they are less likely to grow tumors because they do not multiply as quickly. Adult stem cells have also had success stories unlike embryonic stem cells. There is no need to create an embryo and destroy it for the stem cells if there is a more efficient and ethical way to obtain and use stem cells.
