fish
Regenerative Medicine: New Clue from Fish about Healing Spinal Cord Injuries
Posted on by Dr. Francis Collins
Caption: Tissue section of zebrafish spinal cord regenerating after injury. Glial cells (red) cross the gap between the severed ends first. Neuronal cells (green) soon follow. Cell nuclei are stained blue and purple.
Credit: Mayssa Mokalled and Kenneth Poss, Duke University, Durham, NC
Certain organisms have remarkable abilities to achieve self-healing, and a fascinating example is the zebrafish (Danio rerio), a species of tropical freshwater fish that’s an increasingly popular model organism for biological research. When the fish’s spinal cord is severed, something remarkable happens that doesn’t occur in humans: supportive cells in the nervous system bridge the gap, allowing new nerve tissue to restore the spinal cord to full function within weeks.
Pretty incredible, but how does this occur? NIH-funded researchers have just found an important clue. They’ve discovered that the zebrafish’s damaged cells secrete a molecule known as connective tissue growth factor a (CTGFa) that is essential in regenerating its severed spinal cord. What’s particularly encouraging to those looking for ways to help the 12,000 Americans who suffer spinal cord injuries each year is that humans also produce a form of CTGF. In fact, the researchers found that applying human CTGF near the injured site even accelerated the regenerative process in zebrafish. While this growth factor by itself is unlikely to produce significant spinal cord regeneration in human patients, the findings do offer a promising lead for researchers pursuing the next generation of regenerative therapies.
Snapshots of Life: Fish Awash in Color
Posted on by Dr. Francis Collins
If this image makes you think of a modern art, you’re not alone. But what you’re actually seeing are hundreds of live cells from a tiny bit (0.0003348 square inches) of skin on the tail fin of a genetically engineered adult zebrafish. Zebrafish are normally found in tropical freshwater and are a favorite research model to study vertebrate development and tissue regeneration. The cells have been labeled with a cool, new fluorescent imaging tool called Skinbow. It uniquely color codes cells by getting them to express genes encoding red, green, and blue fluorescent proteins at levels that are randomly determined. The different ratios of these colorful proteins mix to give each cell a distinctive hue when imaged under a microscope. Here, you can see more than 70 detectable Skinbow colors that make individual cells as visually distinct from one another as jellybeans in a jar.
Skinbow is the creation of NIH-supported scientists Chen-Hui Chen and Kenneth Poss at Duke University, Durham, NC, with imaging computational help from collaborators Stefano Di Talia and Alberto Puliafito. As reported recently in the journal Developmental Cell [1], Skinbow’s distinctive spectrum of color occurs primarily in the outermost part of the skin in a layer of non-dividing epithelial cells. Using Skinbow, Poss and colleagues tracked these epithelial cells, individually and as a group, over their entire 2 to 3 week lifespans in the zebrafish. This gave them an unprecedented opportunity to track the cellular dynamics of wound healing or the regeneration of lost tissue over time. While Skinbow only works in zebrafish for now, in theory, it could be adapted to mice and maybe even humans to study skin and possibly other organs.
Bright Lights, Cool Science
Posted on by Dr. Francis Collins
This may look like a tangle of holiday lights, but it’s actually a peek inside the developing brain of a live zebrafish. NIH-supported researchers created this award-winning picture by labeling the brain’s endothelial cells with fluorescent proteins and then using a confocal microscope to snap 3-D images as the cells assembled into the blood-brain barrier. So why are these guys taking photos of fish brains? They want to gain a better understanding of how the blood-brain barrier develops. And that’s important because a major hurdle in the treatment of many brain disorders is figuring out better ways to move drugs and other therapies from the bloodstream and into the brain.
