Stephen Kintz
Dec 11, 2011

Mutant tadpoles, the voltage potential of cells, and regenerating human body parts

Scientists are a strange lot. To the general public, their work can sometimes seem silly or plain ridiculous. Scientists are responsible for creating a monstrous mouse with a human ear growing from its back. They have created bioluminescent kitty-cats; I suspect for easy glow-in-the-dark kitty playtime. Now, scientists have created a tadpole with eyes located improperly on its tail. Yes, you read that right.


Vaibhav Pai and colleagues at Tufts University have published an article on December 7, 2011 in “Development” that claims that by manipulating the transmembrane voltage potential of cells, the scientists were able to determine the location of eye development in embryonic tadpoles [Tufts Press Release] .


Basically, all cells have a voltage potential -- or a non-zero charge. This voltage potential is considered a form of bioelectrical communication between cells, and therefore, it is assumed to be important in determining how cells develop in embryonic development. For example, the cluster of cells that form the eyes will have a specific voltage potential range that is different from the cells that will develop into the spinal cord, heart or lungs.


When Vaibhav Pai and colleagues injected cells on the tadpole's tail with mRNA encoded with ion channels to match the voltage potential on the tadpole's tail with the voltage potential of the cell cluster that normally forms eyes, the scientists were able to form ectopic eyes on the tadpole's tail. The scientists were also able to use voltage potential to grow eyes on the back of the tadpole's head and disrupt the formation of endogenous eyes.


Of course, the researchers were not simply trying to create a terrifyingly topsy-turvy tadpole. The researchers were trying to understand how the body is able to determine which cells develop into which body parts. Moreover, the researchers are hoping that this research will lead to several new innovations within the medical field.


The researchers are hoping that this information will be useful to two main areas of medical research: birth defects and organ re-generation.


Birth defects are an area that might benefit from this research. Since the researchers demonstrated the ability to change the voltage potential of cells at will with no harm to the developing embryonic tadpoles, the same methods might be able to be used on human embryos. For example, if it is demonstrated that an embryo is not developing an organ properly, scientists might be able to induce proper organ growth through the injection of mRNA encoded with the proper ion channels.


This might also lead to the ability to diagnose embryos that have a high chance for malformed organs. Once researchers have determined the voltage potential of the cells for any organ, it is then possible to determine if the embryo is developing normally by placing a small single electrode into the area of interest and measuring the voltage between cells.


Of course, any research on embryos or babies is highly restricted. So, while this research might one day help alleviate birth defects, that day is many years into the future. Moreover, I am unsure how an electrode would be introduced to a human embryo.


Organ regeneration or organ transplantation is the other area that might benefit from this research. In fact, the researchers who published this article are hoping to explore how voltage potential might help with the regeneration of the spinal cord, brain tissues and limbs.


Ideally, voltage potential could facilitate the growing of organs outside of the body; or in the area of brain tissue, limbs and spinal cords injuries, the goal might be to inject cells with particular voltage potentials that repair or regenerate organs.


Now regrowing an arm or spinal cord in an adult human is very different from growing eyes in an embryonic tadpole. However, the researchers are hoping that unraveling the way the body generates organs during embryonic development will lead to methods that can regenerate organs in a non-embryonic setting.


Either way, this strange monstrous tadpole might be the beginning of a whole new branch of re-generative medicine.