FAQs about STEM CELLS

FAQs about STEM CELLS

What are embryonic stem cells?

Embryonic stem cells (ESCs) are cells derived from embryos at the blastocyst stage. This stage is around 5 days after the sperm fertilizes the egg. The blastocyst consists of a ball of cells made up of two cell types:

• the inside cells called inner cell mass. These cells develop into all the cells of the embryo)
• the outside cells called trophoblast, a layer of cells surrounding the inner cell mass. These cells are in contact with cells from the mother's womb and form the placenta.

Stem cells are distinguished from other cell types by two important characteristics. First, they are can self-renew indefinitely. Second, they are pluripotent. This means that under certain physiologic or experimental conditions, they can be induced to become tissue- or organ-specific cells of the entire body.

What are adult stem cells?

Adult stem cells are cells found in many organs and tissues such as the skin, intestines and bone marrow. Stem cells in these organs regularly divide to repair and replace worn out or damaged cells. When a stem cell divides, each new cell has the potential either to remain a stem cell or become a more specialized cell of that organ.

Why do I care about stem cells?

Studying stem cells will help us understand how they transform into the specialized cells of the different organs. Some of the most serious medical conditions, such as degenerative diseases and birth defects, are due to either lack of stem cells, or the lack of stem cells to become the specialized cell of the organ. Understanding how embryonic stem cells develop into the different cell types of the body will provide insights on early human development, an area of study that has been limited due to difficulty in obtaining experimental material and the ethical concerns involving human embryo research. Understanding stem cell biology will also allow us to correct medical conditions due to stem cell defects.

Moreover, hESCs could also be used to test new drugs. For example, new medications could be tested for safety on differentiated cells generated from hESCs. Other kinds of cell lines are already used in this way. Cancer cell lines, for example, are used to screen potential anti-tumor drugs. The availability of hESCs would allow drug testing in a wider range of cell types.

Most importantly, stem cells can be used to generate cells and tissues that could be used for cell-based therapies. Today, donated organs and tissues are often used to replace those that are diseased or destroyed. Unfortunately, the number of people needing transplant far exceeds the number of organs available for transplantation. Stem cells could be made into specialized cells to treat diseases such as Parkinson's disease, amyotrophic lateral sclerosis, spinal cord injury, burns, heart disease, diabetes, and arthritis.

Have human embryonic stem cells successfully treated any human diseases? 

There are currently three clinical trials using cells derived from human embryonic stem cells:

• Geron, a biotechnology company located in California, began enrolling patients in October 2010 for its clinical trial of a hESC-derived therapy. This trial has been designed to test the safety of using hESCs to achieve restoration of spinal cord function: oligodendrocyte progenitor cells derived from hESCs will be injected directly into the lesion site of the patient's injured spinal cord.
• ACT, a biotechnology company based in Santa Monica, California, has been granted FDA permission to begin enrolling patients for Phase I (safety and tolerability) clinical trials of two hESC-derived stem cell products:

1. The first ACT trial proposes to test the safety of hESC-derived retinal cells to treat patients with an eye disease called Stargardt's Macular Dystrophy (SMD). ACT issued a press release announcing this trial on November 22, 2010.
2. The second ACT trial proposes to test the safety of hESC-derived retinal cells to treat patients with age-related macular degeneration. ACT issued a press release announcing this trial on January 3, 2011.

Should I store my child's umbilical cord blood? 

Umbilical cord blood is a source of hematopoietic stem cells. Hematopoietic stem cells can give rise to all the blood cell types. They can be used to treat blood cancers and other blood disorders.

What are induced-pluripotent stem cells? 

Induced pluripotent stem cells (iPSCs) are adult cells (e.g. skin cells or blood cells) that have been genetically altered to an embryonic stem cell–like state. Although these cells meet the defining criteria for ESCs, it is not known if iPSCs and ESCs differ in clinically significant ways. Mouse iPSCs were first reported in 2006, and human iPSCs were first reported in late 2007.

Nonetheless, iPSCs are already useful tools for drug development and modeling of diseases, and scientists hope to use them in transplantation medicine.
This breakthrough discovery is important because firstly, it has created a powerful way to "de-differentiate" cells (it is like making the cells go back in time).  Secondly, tissues made from iPSCs will be a nearly identical match to the cell donor and thus probably avoid rejection by the immune system.

I want to undergo stem cell therapy. What should I do? 

READ THIS: A Closer Look at Stem Cell Treatment by the ISSCR


Acknowledgements
Some information presented here are obtained from http://stemcells.nih.gov/info