Stem Cell Basics | STEM Cell Information (2023)

I. Introduction: What are stem cells, and why are they important?

Stem cells have the remarkable potential to renew themselves. They can develop into many different cell types in the body during early life and growth. Researchers study many different types of stem cells. There are several main categories: the “pluripotent” stem cells (embryonic stem cells and induced pluripotent stem cells) and nonembryonic or somatic stem cells (commonly called “adult” stem cells). Pluripotent stem cells have the ability to differentiate into all of the cells of the adult body. Adult stem cells are found in a tissue or organ and can differentiate to yield the specialized cell types of that tissue or organ.

Pluripotent stem cells

Early mammalian embryos at the blastocyst stage contain two types of cells – cells of the inner cell mass, and cells of the trophectoderm. The trophectodermal cells contribute to the placenta. The inner cell mass will ultimately develop into the specialized cell types, tissues, and organs of the entire body of the organism. Previous work with mouse embryos led to the development of a method in 1998 to derive stem cells from the inner cell mass of preimplantation human embryos and to grow human embryonic stem cells (hESCs) in the laboratory. In 2006, researchers identified conditions that would allow some mature human adult cells to be reprogrammed into an embryonic stem cell-like state. Those reprogramed stem cells are called induced pluripotent stem cells (iPSCs).

Adult stem cells

Throughout the life of the organism, populations of adult stem cells serve as an internal repair system that generates replacements for cells that are lost through normal wear and tear, injury, or disease. Adult stem cells have been identified in many organs and tissues and are generally associated with specific anatomical locations. These stem cells may remain quiescent (non-dividing) for long periods of time until they are activated by a normal need for more cells to maintain and repair tissues.

II. What are the unique properties of all stem cells?

Stem cells have unique abilities to self-renew and to recreate functional tissues.

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Stem cells have the ability to self-renew.

Unlike muscle cells, blood cells, or nerve cells—which do not normally replicate— stem cells may replicate many times. When a stem cell divides, the resulting two daughter cells may be: 1) both stem cells, 2) a stem cell and a more differentiated cell, or 3) both more differentiated cells. What controls the balance between these types of divisions to maintain stem cells at an appropriate level within a given tissue is not yet well known.

Discovering the mechanism behind self-renewal may make it possible to understand how cell fate (stem vs. non-stem) is regulated during normal embryonic development and post-natally, or misregulated as during aging, or even in the development of cancer. Such information may also enable scientists to grow stem cells more efficiently in the laboratory. The specific factors and conditions that allow pluripotent stem cells to remain undifferentiated are of great interest to scientists. It has taken many years of trial and error to learn to derive and maintain pluripotent stem cells in the laboratory without the cells spontaneously differentiating into specific cell types.

Stem cells have the ability to recreate functional tissues.

Pluripotent stem cells are undifferentiated; they do not have any tissue-specific characteristics (such as morphology or gene expression pattern) that allow them to perform specialized functions. Yet they can give rise to all of the differentiated cells in the body, such as heart muscle cells, blood cells, and nerve cells. On the other hand, adult stem cells differentiate to yield the specialized cell types of the tissue or organ in which they reside, and may have defining morphological features and patterns of gene expression reflective of that tissue.

Different types of stems cells have varying degrees of potency; that is, the number of different cell types that they can form. While differentiating, the cell usually goes through several stages, becoming more specialized at each step. Scientists are beginning to understand the signals that trigger each step of the differentiation process. Signals for cell differentiation include factors secreted by other cells, physical contact with neighboring cells, and certain molecules in the microenvironment.

III. How do you culture stem cells in the laboratory?

How are stem cells grown in the laboratory?

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Growing cells in the laboratory is known as “cell culture.” Stem cells can proliferate in laboratory environments in a culture dish that contains a nutrient broth known as culture medium (which is optimized for growing different types of stem cells). Most stem cells attach, divide, and spread over the surface of the dish.

The culture dish becomes crowded as the cells divide, so they need to be re-plated in the process of subculturing, which is repeated periodically many times over many months. Each cycle of subculturing is referred to as a “passage.” The original cells can yield millions of stem cells. At any stage in the process, batches of cells can be frozen and shipped to other laboratories for further culture and experimentation.

How do you “reprogram” regular cells to make iPSCs?

Differentiated cells, such as skin cells, can be reprogrammed back into a pluripotent state. Reprogramming is achieved over several weeks by forced expression of genes that are known to be master regulators of pluripotency. At the end of this process, these master regulators will remodel the expression of an entire network of genes. Features of differentiated cells will be replaced by those associated with the pluripotent state, essentially reversing the developmental process.

How are stem cells stimulated to differentiate?

As long as the pluripotent stem cells are grown in culture under appropriate conditions, they can remain undifferentiated. To generate cultures of specific types of differentiated cells, scientists may change the chemical composition of the culture medium, alter the surface of the culture dish, or modify the cells by forcing the expression of specific genes. Through years of experimentation, scientists have established some basic protocols, or “recipes,” for the differentiation of pluripotent stem cells into some specific cell types (see Figure 1 below).


Stem Cell Basics | STEM Cell Information (1)

(Video) GCSE Biology - What are Stem Cells? Difference Between Embryonic and Adult Stem Cells #11

What laboratory tests are used to identify stem cells?

At various points during the process of generating stem cell lines, scientists test the cells to see whether they exhibit the fundamental properties that make them stem cells. These tests may include:

  • Verifying expression of multiple genes that have been shown to be important for the function of stem cells.
  • Checking the rate of proliferation.
  • Checking the integrity of the genome by examining the chromosomes of selected cells.
  • Demonstrating the differentiation potential of the cells by removing signals that maintain the cells in their undifferentiated state, which will cause pluripotent stem cells to spontaneously differentiate, or by adding signals that induce adult stem cells to differentiate into appropriate cell phenotypes.

IV. How are stem cells used in biomedical research and therapies?

Given their unique regenerative abilities, there are many ways in which human stem cells are being used in biomedical research and therapeutics development.

Understanding the biology of disease and testing drugs

Scientists can use stem cells to learn about human biology and for the development of therapeutics. A better understanding of the genetic and molecular signals that regulate cell division, specialization, and differentiation in stem cells can yield information about how diseases arise and suggest new strategies for therapy. Scientists can use iPSCs made from a patient and differentiate those iPSCs to create “organoids” (small models of organs) or tissue chips for studying diseased cells and testing drugs, with personalized results.

(Video) STEM CELLS: Totipotent, pluripotent, multipotent and unipotent. Learn how iPS cells are made

Cell-based therapies

An important potential application is the generation of cells and tissues for cell-based therapies, also called tissue engineering. The current need for transplantable tissues and organs far outweighs the available supply. Stem cells offer the possibility of a renewable source. There is typically a very small number of adult stem cells in each tissue, and once removed from the body, their capacity to divide is limited, making generation of large quantities of adult stem cells for therapies difficult. In contrast, pluripotent stem cells are less limited by starting material and renewal potential.

To realize the promise of stem cell therapies in diseases, scientists must be able to manipulate stem cells so that they possess the necessary characteristics for successful differentiation, transplantation, and engraftment. Scientists must also develop procedures for the administration of stem cell populations, along with the induction of vascularization (supplying blood vessels), for the regeneration and repair of three-dimensional solid tissues.

To be useful for transplant purposes, stem cells must be reproducibly made to:

  • Proliferate extensively and generate sufficient quantities of cells for replacing lost or damaged tissues.
  • Differentiate into the desired cell type(s).
  • Survive in the recipient after transplant.
  • Integrate into the surrounding tissue after transplant.
  • Avoid rejection by the recipient’s immune system.
  • Function appropriately for the duration of the recipient’s life.

While stem cells offer exciting promise for future therapies, significant technical hurdles remain that will likely only be overcome through years of intensive research.

Note: Currently, the only stem cell-based products that are approved for use by the U.S. Food and Drug Administration (FDA) for use in the United States consist of blood-forming stem cells (hematopoietic progenitor cells) derived from cord blood. These products are approved for limited use in patients with disorders that affect the body system that is involved in the production of blood (called the “hematopoietic” system). TheseFDA-approved stem cell products are listed on the FDA website. Bone marrow also is used for these treatments but is generally not regulated by the FDA for this use. The FDA recommends that people considering stem cell treatments make sure that the treatment is either FDA-approved or being studied under an Investigational New Drug Application (IND), which is a clinical investigation plan submitted and allowed to proceed by the FDA.

V. How does NIH support stem cell research?

NIH conducts and funds basic, translational, and clinical research with a range of different types of stem cells. NIH-supported research with human pluripotent stem cells is conducted under the terms of theNIH Guidelines for Human Stem Cell Research. NIH awards are listed in various categories of stem cell research through theNIH Estimates of Funding for Various Research, Condition, and Disease Categories (RCDC). NIH also supports a major adult stem cell and iPSC research initiative through theRegenerative Medicine Innovation Project.

(Video) GCSE Science Revision Biology "Stem Cells"


What are the 3 main types of stem cells? ›

Different types of stem cell

There are three main types of stem cell: embryonic stem cells. adult stem cells. induced pluripotent stem cells.

What cells are in stem cells? ›

Stem cells are special human cells that are able to develop into many different cell types. This can range from muscle cells to brain cells. In some cases, they can also fix damaged tissues.

What is the main function of stem cells? ›

Stem cells are cells with the potential to develop into many different types of cells in the body. They serve as a repair system for the body. There are two main types of stem cells: embryonic stem cells and adult stem cells.

Where do stem cells come from? ›

Stem cells originate from two main sources: adult body tissues and embryos. Scientists are also working on ways to develop stem cells from other cells, using genetic “reprogramming” techniques.

What is the most common stem cell? ›

Multipotent haematopoietic stem cell (HSC) transplantation is currently the most popular stem cell therapy. Target cells are usually derived from the bone marrow, peripheral blood, or umbilical cord blood [83].

How long do stem cells live? ›

They self-renew and produce progeny to replenish dying or damaged cells throughout an organism's lifetime. Because of these unique characteristics, stem cells are traditionally thought to be immortal and exempt from aging.

What are the benefits of stem cells? ›

While stem cell treatments provide fast recovery, it also increases the functionality, range of motion and flexibility of the joint, muscle or part of the body that was damaged. One of the amazing benefits of stem cell treatments is to help patients restore their injured body part to the way it was prior to the injury.

What are the 4 types of stem cells? ›

Hematopoietic Stem Cells (Blood Stem Cells) Mesenchymal Stem Cells. Neural Stem Cells. Epithelial Stem Cells.

Where do stem cells live? ›

Stem cells mostly live in the bone marrow (the spongy center of certain bones). This is where they divide to make new blood cells. Once blood cells mature, they leave the bone marrow and enter the bloodstream. A small number of the immature stem cells also get into the bloodstream.

What are the four major types of stem cells? ›

Stem cells are often categorized as (1) totipotent, (2) pluripotent, (3) multipotent, or (4) unipotent.

What are 3 main functions of a stem? ›

A stem performs the following functions in a plant: (i) It supports branches, leaves, flowers, and fruits. (ii) It transports water and minerals from the roots to the leaves and other parts of plants. (iii) It transports food from leaves to different parts of the plant.

What are the two main types of stem cells? ›

Researchers study many different types of stem cells. There are several main categories: the “pluripotent” stem cells (embryonic stem cells and induced pluripotent stem cells) and nonembryonic or somatic stem cells (commonly called “adult” stem cells).

How many stem cells are in the human body? ›

Estimates vary from 30-40 trillion, which seems more impressive when written out (like on the lower end): 30,000,000,000,000. If we took a wild stab at the specific stem cell number and said that about 1 in 1,000 cells are of the stem variety then you might guess that there are 30 billion stem cells in the body.

What diseases can stem cells cure? ›

Conditions that stem cell transplants can be used to treat include:
  • severe aplastic anaemia (bone marrow failure)
  • leukaemia – a type of cancer affecting white blood cells.
  • lymphoma – another type of cancer affecting white blood cells.
  • multiple myeloma – cancer affecting cells called plasma cells.

How is stem cell extracted? ›

The most common way to harvest stem cells involves temporarily removing blood from the body, separating out the stem cells, and then returning the blood to the body. To boost the number of stem cells in the blood, medicine that stimulates their production will be given for about 4 days beforehand.

What is the best source of stem cells? ›

The Best Sources Of Stem Cells Explained: Cord Blood, Bone Marrow, and Teeth. Stem cell research is one of the most exciting and rapidly advancing areas of contemporary medicine.

What are cons of stem cells? ›

Cons of the stem cell therapy include: Adult stem cells are hard to grow for long period in culture. There is still no technology available to generate adult stem cells in large quantities. Stimulated pluripotent cells normally do not have any p method of maintenance and reproducibility.

What are some of the risks of stem cells? ›

Until your body starts being able to produce healthy blood cells again, you may be at risk of: iron deficiency anaemia – a lack of red blood cells that can make you feel tired and short of breath; this may be treated with regular blood transfusions.

Can your body run out of stem cells? ›

This process of becoming more specialised is called differentiation. Stem cells can also self-renew, which means that they can replace themselves so that your supply of stem cells doesn't run out.

What stimulates stem cell growth? ›

Vitamins C and D

Vitamin C helps our bone marrow stem cells by promoting their proliferation (increase in numbers). Vitamin D3 can reduce the aging of our stem cells, make them healthier, and help them differentiate, or turn into other types of cells.

Can stem cells reverse aging? ›

Stem cells are a promising potential solution for reversing the visible signs of aging. These special cells have the ability to regenerate damaged tissues and improve overall cellular function, which may lead to a reduction in the appearance of wrinkles and other age-related changes.

What are the benefits and risks of stem cells? ›

While stem cell therapy has the potential to cure many diseases and injuries, there are also some risks associated with this treatment. For example, there is a risk of rejection by the body's immune system, as well as a risk of the stem cells turning into cancer cells.

Why are people against stem cell research? ›

Opponents argue that the research is unethical, because deriving the stem cells destroys the blastocyst, an unimplanted human embryo at the sixth to eighth day of development. As Bush declared when he vetoed last year's stem cell bill, the federal government should not support “the taking of innocent human life.”

What are the two main characteristics of stem cells? ›

Stem cells have the ability to differentiate into specific cell types. The two defining characteristics of a stem cell are perpetual self-renewal and the ability to differentiate into a specialized adult cell type.

What are stem cells for dummies? ›

Stem cells are the building blocks of the human body. At the start of life, they divide over and over again to create a full person from an embryo. As we age, they replenish cells in our blood, bone, skin and organs. Stem cells could be powerful tools in treating injury and illness.

What parts of the body contain stem cells? ›

Stem cells are pretty ubiquitous in the body, appearing in many different organs and tissues including the brain, blood, bone marrow, muscle, skin, heart, and liver tissues. In these areas, they lie dormant until needed to regenerate lost or damaged tissue.

Who Cannot donate stem cells? ›

Autoimmune diseases

Most diseases which may be defined as autoimmune disorders, such as multiple sclerosis, systemic lupus, chronic fatigue syndrome and fibromyalgia, will prevent you from donating marrow or blood-forming cells.

What are the 4 major types of stem cells? ›

Stem cells are often categorized as (1) totipotent, (2) pluripotent, (3) multipotent, or (4) unipotent.

What are the 4 stem cells? ›

Types of Stem Cells
  • Embryonic stem cells.
  • Tissue-specific stem cells.
  • Mesenchymal stem cells.
  • Induced pluripotent stem cells.

What are three types of stem cells and what makes each type unique? ›

There are several main categories: the “pluripotent” stem cells (embryonic stem cells and induced pluripotent stem cells) and nonembryonic or somatic stem cells (commonly called “adult” stem cells). Pluripotent stem cells have the ability to differentiate into all of the cells of the adult body.

Where are stem cells found? ›

Where are stem cells found? Adult stem cells have been found in most parts of the body, including brain, bone marrow, blood vessels, skin, teeth and heart. There are typically a small number of stem cells in each tissue.

What are the 5 types of stem cells? ›

Types of Adult Stem Cells:
  • Hematopoietic Stem Cells (Blood Stem Cells)
  • Mesenchymal Stem Cells.
  • Neural Stem Cells.
  • Epithelial Stem Cells.
  • Skin Stem Cells.

What are 5 uses of stem cells? ›

Potential uses of stem cells

grow new cells in a laboratory to replace damaged organs or tissues. correct parts of organs that don't work properly. research causes of genetic defects in cells. research how diseases occur or why certain cells develop into cancer cells.

What are the benefits of stem cell? ›

The main benefits of stem cells are their ability to differentiate (transform) into any cell type, and their ability to repair damaged tissue. Because of this, researchers think they may have a role in treating a range of medical conditions.


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