SCIENCEPEDIA

There are two main groups of stem cells. There are tissue specific stem cells and pluripotent stem cells. Pluripotent means capable of giving rise to multiple types of cells. Tissue specific stem cells reside in developed tissue and can only give rise to that specific tissue cell. Embryonic stem cells and iPS cells are a pluripotent stem cell. These cells are found in the early embryo (within 3-7 days of existence. Known as a blastocyst). These cells are pluripotent, as they can turn into any cell in the human body. This is a key element in the development of young as an embryo begins as a very small number of cells. Without stem cells, this small number would have to consist of every single type of cell in the human body. There are around 200 different cell types/compositions, each with approximately 20 structures and organelles, which equates to 4,000 different cells, if there were to be one of each type. Now, an embryo, at some point develops from a single cell, a zygote, not 4,000 different ones. This is where stem cells come into the equation. The zygote begins to divide into smaller cells, some of which I assume are the pluripotent stem cells. Then the pluripotent stem cells begin to develop into different cells, depending on which are required. Stem cells divide in order to create new cells. If a single stem cell divides, each one has the potential either to become a more specific, specialised cell, such as a red blood cell or brain cell, or to stay as a stem cell. This give the cells the ability to increase in quantity exponentially.

iPS cells stands for induced Pluripotent Stem cells. These are cells that biologists or immunologists make in the lab. They are ‘induced’ as they are adult cells being encouraged to become stem cells.

Stem cells are useful in science as they can replace lost or damaged cells in our bodies, and they can aid medical research