Totipotent, Pluripotent and Multipotent Stem Cells – What is the Difference?
In this post let us talk about few terms that we frequently use when we talk about stem cells and they can be really confusing sometimes. I am talking about totipotent, pluripotent and multipotent. Like always first thing first. What are stem cells? Stem cells are undifferentiated, unspecialized cells which mean stem cells can differentiate into any type of cell present in our body and we have around 200+ cell types in our body and stem cell can give rise to any of them.
To understand these three terms we should know the categories of stem cells. Stem cells are classified under two categories, embryonic stem cells – found in embryo and adult stem cells – found in many organs. Embryonic stem cells can be either totipotent or pluripotent and adult stem cells are multipotent.
Now once let us try and understand each of the term.
- Totipotent – “totus” means “whole”. So the term is about whole of something. To understand totipotency let us go to fertilization process. When sperm cell fertilizes an egg it results in the zygote formation, we all know that. This zygote will then start dividing and differentiating, giving rise to whole organism. So this ability of zygote that it can differentiate into any type of cell (making a complete organism) is called totipotency. That means a zygote is a cell which is totipotent.
- Pluripotent – “pluri” means “several”. Now once the zygote is formed, it will start dividing and after few divisions it will reach the blastocyst stage. At this stage it is a hollow ball which has a cluster of cells called inner cell mass and a single cell line at the periphery called trophoblast. The inner cell mass of the blastocyst has the ability to produce all the cell types of our body except for what trophoblast can form e.g., placenta, amniotic sac etc. So this means we have around 200+ cell types in our body and inner cell mass can differentiated into any of them, e.g., it can give rise to all the blood cells, cardiac muscles, neural cells. This ability of inner cell mass is called pluripotency. So inner cell mass cells are pluripotent and we wouldn’t call it totipotent because it cannot give rise to what trophoblast cells can.
- Multipotent – “multi” in this case means “few”. As in the classification we saw that multipotent is term related to adult stem cells. Adult stem cells are found in many organs which means they are already specified to differentiate in particular cell line, depending on which organ they are present in. To make it easier to understand let us compare it with pluripotent stem cells. Pluripotent cells, as we already establish can differentiate in any of the cell type but multipotent cell would be more specified for one or more cell lines e.g., mesenchymal stem cell differentiates to form bone, cartilage, connective tissue, adipose tissue etc. So mesenchymal stem cell is multipotent.
Hope I am able to make it clear to you guys:)
Watch a video on this topic here.
