There are many HSCs in the bone marrow, but getting them out in sufficient numbers is laborious—and for the donor, can be a painful process. Small numbers of HSCs circulate within the blood stream, but not nearly enough. And while umbilical cord blood from newborn babies may present a relatively rare but promising source for HSCs, a single cord generally contains fewer cells than are necessary.
And here’s the rub: The demand for HSCs is only going to increase. Once a last resort treatment for aggressive blood cancers, HSCTs are being used for a growing list of conditions, including some solid tumor cancers, non-malignant blood disorders and even a number of metabolic disorders.
If you look at the range of research models available to scientists today (from fungi to flies to mice and larger), one little guy stands out – a tropical freshwater fish from the rivers of Bangladesh called the zebrafish. While it may be small, this fish is having a big impact on medical science, especially in genetics, stem cell biology, and drug screening, as covered in today’s Wall Street Journal.
As we’ve mentioned previously on Vector, the zebrafish is swimming its way into many research programs, both here at Children’s Hospital Boston and across the country. As a model, they are quite attractive to researchers, in part due to their small size, their fecundity, and their surprising similarities to us (from a genetic standpoint, that is).
One of the characteristics that make zebrafish a fantastic model for research is that they spawn…a lot. A healthy female zebrafish can lay upwards of 1,000 eggs each week. By comparison, the mouse, another species widely used in research, may have a single 12-pup litter each month.
Sometimes, though, that isn’t enough. A researcher screening a library of chemicals for potential drugs, for instance, might need tens of thousands of zebrafish embryos, all at the same developmental stage, to have statistically meaningful results.
They’re small, they’re transparent, and they breed at an amazing rate. They may hold the key to understanding the genetics of many human diseases. And they may help scientists discover new drugs – quicker and cheaper. Oh, and they’re fish.
The zebrafish (Danio rerio to the taxonomists) is a striped tropical fish, no longer than your pinky finger, that looks like it would be more at home in someone’s aquarium than in a laboratory. But for several reasons, zebrafish are powerful organisms for stem cell, developmental, and genetic research:
Despite our distance from zebrafish on the evolutionary tree, they’re surprisingly similar to us from a genetic standpoint.
Because of their small size, they can be housed at high densities.
Compared to other model organisms like mice, they’re relatively inexpensive to care for.
An adult female zebrafish can lay 300 eggs each week. By comparison, a mouse might have a single 12-pup litter each month.
Their skin is permeable, so they can absorb drugs directly from the water of their tank.
Zebrafish embryos are transparent, offering a window into their bodies; some lines, like Casper, remain transparent through adulthood. …