Regenerative Medicine: New Clue from Fish about Healing Spinal Cord Injuries

Zebrafish Spinal Cord

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.

Continue reading

Charting the Chemical Choreography of Brain Development

Drawing of baby, adolescent, and adult with decorative brains

Credit: Image courtesy of Scot Nicholls

Once in a while a research publication reveals an entirely new perspective on a fundamental issue in biology or medicine. Today’s blog is about such a paper. The story, though complex, is very significant.

The choreography of human brain development is amazing, but quite mysterious. Today’s post highlights a study [1] that reveals the locations of some of the chemical choreographers that collaborate with DNA to orchestrate these fancy moves in the brain. Continue reading

Mice Learn Better with Help from Human Brain Cells

Photo image of human astrocytes

Human astrocytes in a mouse brain
Source: Steven Goldman, M.D., Ph.D., University of Rochester Medical Center

What happens when you implant human glia—a type of brain cell that protects and nurtures neurons—into the brains of newborn mice? Well, it turns out these glia mature into multi-talented astrocyte cells that provide nutrients, repair injuries, and modulate signals just like they do in a human brain. They even assume the same complex star shape!

We know the cells in question are indeed human astrocytes because they produce a group of specific proteins, which are tagged with a combination of dyes that together appear yellow in this image. In contrast, the mouse cells are blue.

This all looks very pretty, but you might wonder what impact these human astrocytes have on mouse cognition. Researchers found mice that received the implants were better able to learn and remember than those that didn’t. In short, the human cells seem to have made the mice smarter.

Interestingly, human astrocytes are larger, more complex, and more diverse than their counterparts in other species. So, perhaps these cells may hold some of the keys to our own unique cognitive abilities.

Reference:

Forebrain Engraftment
by Human Glial Progenitor Cells Enhances Synaptic Plasticity and Learning in Adult Mice. Xiaoning Han, Michael Chen, Fushun Wang, Martha Windrem, Su Wang, Steven Shanz, Qiwu Xu, Nancy Ann Oberheim, Lane Bekar,  Sarah Betstadt,  Alcino J. Silva, Takahiro Takano, Steven A. Goldman, and Maiken Nedergaard. Cell Stem Cell 12, 342–353, March 7, 2013.

NIH support: the National Institute of Mental Health; and the National Institute of Neurological Disorders and Stroke