Stem Cells: The Origin Story

By Diya Ramesh (’23)

Superheroes. Every little child (or child at heart) idolizes them and aspires to be just like them. What’s not to love? They’re strong, powerful, brave citizens that use their talents to enforce justice in the world. Best of all, they have amazing super powers. Imagine being able to fly, have super strength, shoot lasers from your hands, or even change form. Wait a minute, you don’t have to, because you have stem cells, which are a veritable super power in their own right. Confused? Well, stick around to clear your doubts and learn the science behind this amazing part of the human body.

Before we understand stem cells, we need to understand the specialization of cells in the body. Think of the human body like a society or a city. There are many different people with various jobs that they are trained and suited to do. You wouldn’t want your plumber doing your surgery or your dentist building your house. Similarly, there are different cell types in the body, each with its own function or set of functions that it performs. However, just like in human society, cells don’t always begin this way. We humans are not born with our jobs assigned to us, but we eventually have these jobs. Similarly, in the human body, when a sperm cell fertilizes an egg cell, they form a zygote. The zygote is one cell, but it will divide to form a blastocyst, which, in turn, will become an embryo, which will become a human fetus, which eventually will be born as a human infant. During the process of development, these cells will eventually differentiate, or specialize, into specific cells with specific functions. However, what we are interested in are undifferentiated cells, meaning cells with no one job. These cells can essentially become any different type of cell or even other stem cells.

Additionally, there are different types of stem cells with different characteristics. Two of the main classifications are adult stem cells and embryonic stem cells. Adult stem cells (also called somatic stem cells) exist throughout people’s lives. Although they don’t have one function, they are more specialized than embryonic stem cells, and they are used in different parts of the body to become cells needed in that area, such as how stem cells in the bone marrow differentiate to replenish different blood cell types. Embryonic stem cells, on the other hand, have far more cells that they can become. As the name suggests, they originate from human embryos. So, since they have to eventually become all types of cells in the body, they have the capability to become a much wider variety of cell types. Note that there are also smaller categories, more specific categories, which are created based on a stem cell’s potency, or the amount of different types of cells that it can become. 

Now you may start to wonder what is so special about these cells. You may argue that they don’t even have a set purpose or type. Well, it’s actually this potential that makes them powerful. Scientists are trying to harness this capability to fight diseases and change lives. Want to know more? Well, stick around for “Stem Cells: The Superhero Sequel”.

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