Stem cells help block cancer in mice

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Stem cells help block cancer in mice

Tumors killed, healthy cells untouched, scientists say

WASHINGTON - Stem cells, immature cells already showing promise as

tools to regenerate and replace damaged tissue, may also help target

and destroy cancer, U.S. scientists said on Monday.

Tests in mice showed the cells could deliver powerful cancer-killing

proteins, destroying tumors while leaving healthy cells untouched.

Dr. Andreeff and colleagues at the University of Texas M. D.

Cancer Center in Houston used cells taken from bone marrow.

These immature cells, known as mesenchymal stem cells, usually give

rise to muscle and other tissues.

The researchers genetically engineered these cells to carry interferon

alpha, an immune system protein that can help kill cancer cells, or a

cancer-destroying virus.

GUIDE Stem cell research

Harvesting stem cells

• Step One

• Step Two

• Step Three

• Step Four

Glossary

Embryonic stem cells used in research most often come from embryos

left over after in vitro fertilization procedures.

Step One: An egg is fertilized by a sperm in a lab dish.

Step Two: The fertilized egg begins to divide and develop into an

embryo. About five days later, the embryo becomes a blastocyst -- a

hollow ball of about 100 cells. The inner cells are the embryonic stem

cells.

Step Three: Stem cells are removed from the blastocyst and cultured in

the laboratory where they theoretically can multiply indefinitely.

Step Four: By adding and removing certain proteins, scientists can

coax the cells to develop into new heart, bone, nerve or other cells

to treat diseases.

Assisted reproductive technology: Fertility treatments that involve a

laboratory handling eggs or embryos, such as in vitro fertilization.

Blastocyst: A preimplantation embryo of 30 to 150 cells.

Differentiation: The process by which early unspecified cells acquire

the features of specific cells such as heart tissue, liver or muscle.

Embryo: The earliest stage of development from the single cell to

implantation in the uterus.

Embryonic stem cell: A cell from an embryo that has the potential to

become a wide variety of specialized cell types.

In vitro: Done outside the body.

In vivo: Done within the living body.

Tissue or cell culture: Growth of tissue in a laboratory dish for

experimental research.

Source: Associated Press, MSNBC research • Print this

Cells attracted to cancers

In mice these cells slowed several kinds of leukemia, attacked

melanoma -- skin cancer and breast cancer cells --that had spread to

the lung, and tackled brain tumors.

The approach cured 70 percent of mice implanted with one kind of human

ovarian cancer, the researchers told a meeting of the American

Association of Cancer Research in Orlando, Florida.

" This drug delivery system is attracted to cancers, both primary and

metastatic, and anti-tumor effects are observed when the cells

integrate into the tumor micro-environment, " Andreeff said in a

statement.

" The most important discovery here is that these cells are capable of

migrating from the bone marrow or blood circulation selectively into

tumors and produce anti-tumor agents only at the sites of these tumors

and their metastasis. "

Andreeff said tumors attract mesenchymal stem cells by sending out

signals similar to those sent by damaged tissue.

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