Bioelectricity gets a leg up

Electricity is essential for complex organisms to form and function as cohesive wholes. Nerves carry electric information throughout the body. Ion pumps and channels shuttle charged particles across cell membranes, sending signals from one cell to another and setting up transmembrane electric potentials (V_mem) that help to tell the cells what their role is in the body. Broadly speaking, fully differentiated cells in tissues that have finished forming—muscles, nerves, most organs, and the like—have relatively large V_mem (50–90 mV), whereas embryonic cells, stem cells, and cancer cells have lower V_mem. Michael Levin and colleagues at Tufts University have now shown that not only can V_mem provide new insight into how complex organisms form naturally, but artificially manipulating V_mem can change how they form. For example, a frog whose leg is cut off doesn’t normally grow a new one. But by chemically treating the cells at the site of the wound to lower their V_mem, the researchers found that they could get the leg to regrow. The new limb included nerves, muscles, toes, and toenails—even though the chemical treatment itself contained no information about those structures. Levin and colleagues envision that a similar procedure could someday be applied to human patients—long before bioengineers are capable of building replacement limbs by hand using stem cells. They’re also looking into using V_mem to detect and suppress cancerous tumors. (A.-S. Tseng, M. Levin, Commun. Integr. Biol. 6, 1, 2013.)—Johanna Miller