What Are Stem Cells?

stem-cells-what-are-stem-cellsA cell is the smallest unit of living matter and the functional basic unit of life. The human body is composed of 100 trillion cells and each cell is assigned a specialized function to perform. Some cells function in the brain (neurons), while others function in our hearts (cardiac myocytes), our skin (fibroblasts), and our pancreas (pancreatic cells), etc.

Before a cell becomes specialized, it is a stem cell. Stem cells have two unique properties:

  • Stem cells can multiply
  • Stem cells can become other types of cells

Stem cells are blank impressionable cells until particular factors, or nutrients, induce them to perform a particular function. Stem cells can divide and create progeny; they are often referred to as “progenitor” cells because they can reproduce copies of themselves. The process of unspecialized cells becoming specialized cells is called differentiation (becoming other cell types). During differentiation, the cell goes through several stages, becoming more specialized at each step. Scientists are working to understand what prompts each step of the differentiation process.

Before more recent developments in the field, stem cell scientists around the world relied on embryonic stem cells – cells from embryos – for their research studies. This was controversial and was also slowed significantly by funding obstacles. Scientists have now discovered an alternative, called an induced pluripotent stem (iPS) cell (or iPSC), which holds incredible promise for research as no embryos are involved in their formation. In fact, these newer stem cells can be made from skin cells or even blood cells. Coriell does not participate in embryonic stem cell research; rather, we are working to advance the promise of induced pluripotent stem cells.

Why Are Stem Cells so Important?

Given their unique regenerative abilities, stem cells offer researchers the ability to investigate disease and develop appropriate treatments.

Stem Cell Science

stem-cells-what-are-stem-cells-2stem-cells-what-are-stem-cells-3The potency of a cell specifies its potential to differentiate into different cell types.

Totipotency is the ability of a single cell to divide and produce all the differentiated cell types. Human development begins when a sperm fertilizes an egg and creates a single totipotent cell called a zygote.

Pluripotency refers to a stem cell that has the potential to differentiate into any of the three germ layers that create all of the tissues and organs in a human:
Endoderm – interior stomach lining, gastrointestinal tract, lungs
Mesoderm – muscle, bone, blood, urogenital
Ectoderm – epidermal tissues and nervous system

Multipotent cells have the potential to give rise to cells from multiple, but a limited number of, lineages. An example of a multipotent stem cell is a blood stem cell that can develop into several types of blood cells, but cannot develop into brain cells or other types of cells.

In cell biology, a unipotent cell is one that has the capacity to differentiate into only one type of cell. The most common of these in humans are skin cells. These cells have a unique property of being able to self-renew.