When someone suffers a fully severed spinal cord, it’s considered highly unlikely the injury will heal on its own. That’s because the spinal cord’s neural tissue is notorious for its inability to bridge large gaps and reconnect in ways that restore vital functions. But the image above is a hopeful sight that one day that could change.
Here, a mouse neural stem cell (blue and green) sits in a lab dish, atop a special gel containing a mat of synthetic nanofibers (purple). The cell is growing and sending out spindly appendages, called axons (green), in an attempt to re-establish connections with other nearby nerve cells.
Tags: axons, bioengineering, biomaterials, FASEB Bioart 2016, nanofiber gel, nanofibers, neural stem cell, neurons, regenerative medicine, Scanning electron microscope, spinal cord, spinal cord injuries, stem cell, tissue engineering, tissue regeneration, traumatic injury, wound healing
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.
Tags: connective tissue growth factor a, CTGF, Danio rerio, fish, glia, glial bridges, glial cells, growth factor, model organisms, nerve cells, nervous system, regenerative medicine, self-healing, spinal cord, spinal cord injuries, tissue engineering, tissue regeneration, traumatic injury, wound healing, zebrafish
Jessica Whited enjoys spending time with her 6-year-old twin boys, reading them stories, and letting their imaginations roam. One thing Whited doesn’t need to feed their curiosity about, however, is salamanders—they hear about those from Mom almost every day. Whited already has about 1,000 rare axolotl salamanders in her lab at Harvard University and Brigham and Women’s Hospital, Cambridge, MA. But caring for the 9-inch amphibians, which originate from the lakes and canals underlying Mexico City, certainly isn’t child’s play. Axolotls are entirely aquatic–their name translates to “water monster”; they like to bite each other; and they take 9 months to reach adulthood.
Like many other species of salamander, the axolotl (Ambystoma mexicanum) possesses a remarkable, almost magical, ability to grow back lost or damaged limbs. Whited’s interest in this power of limb regeneration earned her a 2015 NIH Director’s New Innovator Award. Her goal is to discover how the limbs of these salamanders know exactly where they’ve been injured and start regrowing from precisely that point, while at the same time forging vital new nerve connections to the brain. Ultimately, she hopes her work will help develop strategies to explore the possibility of “awakening” this regenerative ability in humans with injured or severed limbs.
Tags: 2015 NIH Director’s New Innovator Award, Ambystoma mexicanum, amphibian, axolotl, axolotl salamander, blastema, CRISPR-Cas, limb regeneration, regenerative medicine, salamander, single cell analysis, single cell sequencing, tissue regeneration, transcriptome, vertebrate, wound epidermis, wound healing
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 , 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.
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