Scientists and Their Opinions

We emailed several scientists and doctors to ask them different questions about stem cells and their opinions on them. Here are the questions we asked them and the answers we received.

David T. Harris, PhD


What are embryonic stem-cell transplants?

There are no embryonic stem cell transplants as these cells when put in vivo cause a type of tumor called a teratoma. Transplants are done with cells derived from ES cells.


What is your opinion on stem-cell transplants?

Each year stem cell transplants using bone marrow and cord blood stem cells saves the lives of more than 40,000 people in the USA with cancer.


How do you preform stem-cell transplants?

Patients are given chemotherapy to eliminate the cancer, infused with stem cells from a donor and then given immunsuppressive drugs to prevent rejection. Works about 60% of time.


Where do stem-cells come from?

Stem cells are found in all organs and tissues of the body. However, the easiest place to obtain stem cells is bone marrow, cord blood and fat.


What are the potential uses of human embryonic stem cells?

Generally, its thought that they serve as good models systems and for discovery.


Are stem-cell transplants illegal, or are there just a lot of restrictions on them that make them seem illegal?

Stem cell transplants for cancer at done routinely in the US at 40,000 per year. Embryonic and fetal stem cell transplants are not done because they result in cancers. Other types of stem cell therapies are permitted.

Ales Cvekl, PhD

What are embryonic stem-cell transplants?

What is your opinion on stem-cell transplants?

How do you preform stem-cell transplants?

Where do stem-cells come from?

What are the potential uses of human embryonic stem cells?

What can stem-cells teach us?

The term used "embryonic stem-cell transplants" is misleading. I think that the correct term is "tissue transplants derived from differentiation of embryonic stem (ES) cells". I am not aware of any work in the eye field where pluripotent ES cells would be transplanted into the eye. The current experiments are aimed to replace lost cells in the eye by a) "transplanting" fully differentiated cells, for example grown as sheets of cells in special gels, into the damaged area and hoping that they will functionally integrate, or b) using suspensions of retinal progenitor cells and injected into the sub retinal space with the hope that these cells will divide, migrate and terminally differentiate where needed. With this clarification you can learn from many web sites, e.g. NIH and HHMI, the rest.

Dr. Cvekl


How would you define "Stem-cells"?

The ES cells can give rise to any cell type in the body, are pluripotent. Other types of stem cells differentiate into a limited number of adult cell types. Example: corneal stem cells (reside in "limbus") and make new corneal epithelium as we loose these cells all the time from the outer surface of the eye as we blink.


The term "ES cells" refer to inner cell mass component of the blastocyst, after they are taken away and cultured in special medium on dish, to keep their pluripotency. The ES cells are thus like other cell lines store in liquid nitrogen, grown on dish, and can be differentiated into various cell types and primitive organs ("organoids", e.g. retinal organoies, kidney organdies, intestinal organdies, ...) in dish.

Carl Schildkraut, PhD

What is Bonafide Erythroid?

Good question


There are many cell types on the pathway to erythroid cells. So fithe cells he obtains are not 100% differentiated they are not guaranteed to be e.

Sunshine Weaver

We are currently in the process of interviewing Sunshine Weaver. She is the mother of an 8 year old boy who was cured of leukemia by adult stem-cells.