Types of Stem Cells: Where They Come From and Which Are Used in Therapy

What makes a cell a stem cell?

A stem cell can do two things other cells cannot: copy itself many times, and give rise to more specialized cells. How many cell types it can become is called its potency.

Multipotent cells are the ones most relevant to treatment today. They are more limited than pluripotent cells, which also makes them more predictable and safer to use.

The main types of stem cells

1. Embryonic stem cells

They are obtained from the inner cell mass of a blastocyst, an embryo of about five days, usually donated from in vitro fertilization with the consent of the donors. They are pluripotent, which makes them powerful for research but also carries a risk of forming tumors, and their use raises ethical debates. Their use in patients is limited to clinical trials.

2. Adult (tissue-specific) stem cells

They live in many tissues and help maintain and repair them. Two groups matter most in medicine:

• Hematopoietic (blood-forming) stem cells, from bone marrow, blood and cord blood. Their transplant is an established treatment for leukemia, lymphoma and other blood disorders.
• Mesenchymal stem (stromal) cells, found in bone marrow, fat and other tissues. They can form bone, cartilage and fat, and they release signals that modulate inflammation. The International Society for Cellular Therapy defined the minimum criteria to identify them in 2006.

3. Perinatal stem cells (umbilical cord and placenta)

Cord blood is rich in blood-forming stem cells and is the source of most FDA-approved stem cell products. The cord tissue itself, including Wharton’s jelly, contains mesenchymal cells that are collected after a healthy birth, with the mother’s consent, without harming mother or baby.

4. Induced pluripotent stem cells (iPSCs)

In 2006 Shinya Yamanaka’s team showed that adult cells can be reprogrammed into a pluripotent state, a discovery later recognized with the Nobel Prize. iPSCs avoid the use of embryos and are a major research tool, but treatments based on them are still in early clinical trials.

Where do stem cells come from?

Cells from your own body are called autologous; cells from a donor are allogeneic. Each has pros and cons: your own cells carry no risk of rejection but require a harvest procedure, and their quality can decline with age; donor cells avoid the harvest but must come from a properly screened and certified source.

Which stem cells are used in therapy today?

• Established: blood-forming stem cell transplants for blood cancers and some immune disorders.
• Used, with evolving evidence: mesenchymal stem cells for osteoarthritis, tendon and ligament injuries. See the evidence in our pros and cons guide.
• Research and clinical trials: embryonic and induced pluripotent stem cells, for example in eye diseases, Parkinson’s disease and diabetes.

At Stem Cell Medellin, regenerative protocols for knee, hip, shoulder and back pain work with mesenchymal stem cells. Dr. Catalina Henao explains in your consultation which source is proposed for your case and why.

Frequently asked questions

What are the 4 types of stem cells?

Embryonic stem cells, adult or tissue-specific stem cells (including mesenchymal and blood-forming cells), perinatal stem cells from the umbilical cord and placenta, and induced pluripotent stem cells created in the lab.

Where do stem cells come from?

From embryos, bone marrow, fat tissue, umbilical cord blood and tissue, and from adult cells reprogrammed in the laboratory. Every adult also has stem cells in several tissues.

What is a multipotent stem cell?

A stem cell that can become several cell types within one family. Mesenchymal stem cells, for example, can form bone, cartilage and fat; blood-forming stem cells produce all blood cells.

Are embryonic stem cells used to treat joint pain?

No. Treatments for joint and tendon pain use adult or perinatal mesenchymal cells. Embryonic stem cells are only used in research and clinical trials.

Which stem cells are FDA approved?

The FDA-approved stem cell products are mostly umbilical cord blood products used for blood and immune disorders. No stem cell product is approved for orthopedic conditions.