AP Biology class blog for discussing current research in Biology

Tag: spinal cord

Just Keep Swimming…and Fixing Paralysis!


Zebrafish (Danio rerio)

Zebrafish (Danio rerio)- from Flickr

The zebrafish may just look like a cute aquatic animal, but they actually have a unique power that humans don’t: they can heal a severed spinal cord. While this uncanny ability sounds almost magical, it can be explained by the work of a certain protein, CTGF (connective tissue growth factor), that humans have as well. Because of this commonality, recent research conducted by Duke University suggests that by learning from the mechanism that allows the Zebrafish to do this, humans may eventually be able to regenerate their lost spinal tissue!

Essentially, the zebrafish is able to regenerate their spinal cord by forming a cellular bridge across the damaged or missing area. They can be fully healed in as little as 8 weeks! But how is this “bridge” possible on a molecular level? When the fish get injured, dozens of genes get activated. Seven of these genes code for proteins that are secreted from cells. The researchers at Duke found that CTGF, one of these proteins, is crucial to the bridge-making process. They found this by looking at the glia, which are the supporting cells that help initially form the bridge before the arrival of nerve cells. After forming the bridge, CTGF levels rose marginally in these glia. When the researchers genetically deleted CTGF from the glia, the whole regeneration process failed. This research proved exciting because humans also have a very similar form of CTGF, and when they added this human-version of the gene to the glia, regeneration was even faster, only taking 2 weeks! The researchers even discovered which of the four parts of CTGF was the important one in this regeneration phenomenon, which in the future would make it easier to create therapies modeled after this part for humans.

However, using this knowledge to help human tissue regeneration is not as straightforward as it may seem. Mammals such as ourselves form scar tissue around damaged areas, complicating the matter further. The group plans on experimenting with other mammals, namely mice to compare and contrast their CTGF levels with those of zebrafish. Do you think that CTGF research is the best way to achieve human tissue regeneration? Is there any way to prevent scar tissue from forming around our wounds? Let me know in the comments!


Original Article:

Photo Credit to Tohru Murakami:

Spinal Neurogenesis

An astrocyte cell grown in tissue culture as viewed by Gerry Shaw

Normally, when spinal neurons are lost during life due to disease or injury, they are lost for good, however, thanks to a recent study done by  Zhida Su and his colleagues at the University of Texas Southwestern Medical Center that may no longer be the case. The team took astrocytes—star-shaped support cells in the nervous system— from the spines of living mice and converted them into neurons. This research was based of the previous works of  Marius Wernig from the Stanford University School of Medicine, who first converted rat skin cells into stem cell like cells and then into neurons, Benedikt Berninger from Ludwig Maximillians University Munich, who took certain brain cells and turned them into neurons, and Olof Torper from Lund University, who transformed astroytes from the brains of mice into neurons. Su and his team were drawn to spinal astrocytes because they form scar tissue after spinal cord injuries.

Su and his team accomplished this transformation by injecting a series of viruses into the mice, one of which, SOX2, managed to convert the spinal astrocytes into neuroblasts, both in culture and in living mice who had suffered spinal injuries. Some of these neuroblasts then went on to form functioning neurons and with the addition of valproic acid the number of cells which matured doubled and actually interacted with existing motor neurons.  Although this process is slow and can take up to four weeks, it is incredibly promising and it is even suggested that, “For each reprogrammed [cell], perhaps more than one new neuron could be generated,” meaning that each neuroblast could divide and create multiple neurons. Although this research is extremely promising, only 3-6% of astrocytes effected become neuroblasts which has been in no way enough to study the effects on the health of the mice. However, this research is very young and could lead to major achievments in neurogenesis in the future and the “curing” of paralysis and other conditions that result from the destruction of neurons.

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