Adult Stem Cells and Induced Pluripotent Stem Cells
Regenerative Medicine and Stem Cells 101
Regenerative medicine and stem cell therapy is a relatively new area of medicine. This article introduces consumers and patients with adult stem cells and induced pluripotent stem cells and explains their role in how human cells develop.
What is an adult stem cell?
LMK: Although the precise origin of adult stem cells is still unproven, the consensus is that adult stem cells are derived from the next stage in embryonic development—when a layer of reproducing cells in the blastocyst forms three germ cell layers of the embryo (eg, ectoderm, mesoderm, endoderm).
Adult stem cells are highly capable. Consider—the human skeleton completely replaces itself about every seven years. This feat would be impossible without adult stem cells—resourceful little players who sense when duty calls to replace—for example, bone. Inside bone, adult stem cells mature into osteoclasts that devour old bone in conjunction with osteoblasts that create new bone. These processes are in part governed by the effects of specific chemical messengers in the plasma (blood) called growth factors. Growth factors stimulate cell growth.
What are the sources of adult stem cells in the human body?
LMK: It is believed that every organ in the human body has a source of adult multipotent stem cells—meaning, they can develop into limited types of cells. There are specific storage sites in the body where stem cells are more plentiful, therefore, physicians harvest (remove by a medical procedure) from these sites.
- Bone marrow (where blood is produced), is usually taken from the hip bones
- Adipose fat tissue (eg, abdominal area)
Both areas are plentiful for harvesting mesenchymal adult stem cells, that can become different types of cells—bone cells, cartilage cells, muscle cells, and fat cells.
After the three primitive germ layers form in the embryo (ectoderm, mesoderm, endoderm) the cells become multipotent—they can develop into limited types of cells. However, multipotent cells cannot become pluripotent (ie, able to develop into any human cell type).
What are induced pluripotent stem cells? Why are they important?
LMK: A pluripotent stem cell can develop into any type of human cell. The importance of induced pluripotent stem cells was revealed in part by Shinya Yamanaka, MD, PhD, who is well-known for his in-depth research about stem cells. He received the 2012 Nobel Prize in Physiology/Medicine for his impressive research.
Dr. Yamanaka’s work is pivotal to induced pluripotent stem cells. He developed a technique that induces a mature human cell after genetic alteration to develop in reverse. In other words, the cell reverts back to a near embryonic stem cell state. These cells are therefore called induced pluripotent stem cells, and they have the ability to develop into any type of cell.
These cells overcome the ethical issues associated with embryonic stem cells because no embryos are used or destroyed. Furthermore, because the patient’s own adult stem cells are utilized, the immune system recognizes the cell as its own and rejection is avoided. Induced stem cells are a topic of considerable research today, and it is hoped they will be capable of therapeutic applications soon.
Off-label Statement: The US Food and Drug Administration (FDA) has not approved stem cell-based products, except for blood forming stem cells used to treat certain types of cancers.1 When certain products (eg, platelet rich plasma) are used by a medical professional, it’s use is termed “off-label”.2
To learn about Dr. Kamhi’s practice, click here.