They've got eyes in the back of their head: Researchers create mutant tadpoles with body parts on their tails
- Scientists grew new organs by changing bioelectric signals in cells
- Further research planned targeting brain, spinal cord and limbs of tadpole embyos
By Nadia Gilani
Frankenstein-style creatures, including tadpoles with eyes on their backs and tails, have been created by scientists, it was revealed today.
US researchers have been able to grow new organs in parts of the body where they don't normally grow by changing bioelectric signals in cells.
The groundbreaking findings mean that complex organs can be created for transplantation or regenerative therapy, the researchers claim.
All-seeing: An eye created by scientists can be seen on this tadpole shown with a red arrow pointing to it
The scientists could even pick the type of organ which was created and specify the location by altering the bioelectrical communication between the animal's cells.
The researchers, from Tuft's University in Massachusetts achieved the most shocking results when they genetically manipulated the membrane voltage of cells in the frog embryo's back and tail and created new eyes - well outside the area they normally form.
Dr Vaibhav Pai, who led the study, said: 'The hypothesis is that for every structure in the body there is a specific membrane voltage range that drives organogenesis.
'These were cells in regions that were never thought to be able to form eyes.
'This suggests that cells from anywhere in the body can be driven to form an eye.'
To create the eye they changed the voltage gradient of cells in the chosen area to match that of normal eye cells.
The findings mean they have identified an entirely new control mechanism that can be used to induce the formation of complex organs for transplantation or regenerative medicine applications, they claim.
Professor Michael Levin, part of the research team said: 'These results reveal a new regulator of eye formation during development, and suggest novel approaches for the detection and repair of birth defects affecting the visual system.
Groundbreaking: Scientists have altered the natural bioelectrical communication among cells for the first time
'Aside from the regenerative medicine applications of this new technique for eyes, this is a first step to cracking the bioelectric code.'
The paper, entitled Transmembrane Voltage Potential Controls Embryonic Eye Patterning in Xenopus laevis is published in the journal Development.
The biologists wanted to understand how cells use natural electrical signals to communicate to create and place body organs.
They identified and marked hyperpolarized cell clusters, which are more negatively charged, located in the head region of the frog embryo and found they expressed genes that are involved in building the eye called Eye Field Transcription Factors (EFTFs).
When they examined the cells fluorescence microscopy showed that the hyperpolarized cells contributed to development of the lens and retina and they believed that these cells turned on genes necessary for building the eye.
They found that when they changed the bioelectric code, or depolarized the cells, it affected normal eye formation.
The cells were then injected with mRNA encoding on channels, a class of gating proteins embedded in the membranes of the cell.
Each channel then selectively allows a charged particle to pass in and out of the cell.
Using these channels the researchers changed the membrane potential of the cells, which affected expression of EFTF genes, causing abnormalities to occur.
The tadpoles used were normal but some had deformed or no eyes and researchers could also control the incidence of abnormal eyes by manipulating the voltage gradient in the embryo.
Dr Pai said: 'Abnormalities were proportional to the extent of disruptive depolarization.
'We developed techniques to raise or lower voltage potential to control gene expression.'
The team now plans further research which will also target the brain, spinal cord and limbs of the embryos.
Professor Levin added: The findings will allow us to have much better control of tissue and organ pattern formation in general.
'We are developing new applications of molecular bioelectricity in limb regeneration, brain repair, and synthetic biology.'