According to National Institutes of Health, hESCs are stem cells taken from human embryos, which are fertilized under an artificial laboratory environment rather than in the productive system of a woman. These embryos are not initially made for scientific research, but they are redundant ones from in vitro fertilization (2009). After five days since fertilized, the zygote develops into a blastocyst, which is a hollow ball with an inner cell mass. And it is in this stage that the hESCs are extracted and then grown in the …show more content…
While hESCs are pluripotent, which means that they have ability to turn into a wide range of specialized types of cells, ASCs have limits in their differentiation capacity. They are able to transform into some major types of cells only. In terms of origins, ASCs are assumed to locate in a separated area within each tissue, where they remain inactive for long periods of time. Only when they receive signals do they become specialized to repair damaged cells. After removed from the body, ASCs still need to be expanded in population in laboratories. Generally, ASCs exist in lower quantities and it is more challenging to grow a high number of ASCs than that of hESCs. (National Institutes of Health,