Fully Transparent Zebrafish Shows How Melanoma Cells Spread to the Skin

Researchers at Children’s Hospital Boston created a zebrafish that is transparent throughout its life and used it to discover that metastasis isn’t random.

The transparent fish was created by mating two existing zebrafish breeds: a breed that lacks the reflective pigment and one that lacks the black pigment. The offspring only had a yellow pigment in their skin, essentially looking clear.

To examine how a cancer spreads, investigators created a fluorescent melanoma tumor in the transparent fish’s abdominal cavity. They report observing that the cancer cells began to spread within five days. They also saw individual cells metastasize.

The spreading melanoma cells appeared to home to the skin after leaving the abdominal cavity. “This told us that when tumor cells spread to other parts in the body, they don’t do it randomly,” remarks Richard White, M.D., Ph.D., a clinical fellow in the Stem Cell Program. “They know where to go.”

The fish’s brain, heart, and digestive tract are also visible allowing the study  of genetic defects of these organs from early embryonic development through adulthood, the scientists note. The also demonstrated that the blood stream is also observable and could be used to answer questions related to stem-cell transplant rejection.

The paper will be published in the February 7 issue of Cell Stem Cell.