Ever wonder how the alien Jack Jeebs in Men in Black is able to regenerate his head? He doesn't like doing it but, still, whenever Agent K shoots him in the head, he just grows a new one. That's useful. Or how is it Wolverine can quickly regenerate and heal the damaged parts of his body? Based on a recent paper in Genes & Development, it could be an overabundance of laminin-511, a molecule that signals cells to start growing hair. 

Scientists at the Stanford University School of Medicine used genetically engineered mouse embryos to demonstrate that laminin-511 signals embryonic stem cells in the skin to start growing hair. "Now we have a signal protein that can support the micro-environment for hair development, and maybe also for hair renewal," said lead author Jing Gao, MD.

The work has implications beyond hair growth: Scientists say the molecule could play a role in the development of other organs and limbs. "Laminin-511 acts at the crossroads between cell compartments, helping the cells communicate," said senior author Peter Marinkovich, MD. "It works through antennae called primary cilia." Those primary cilia also help drive formation of kidneys, craniofacial structures and limbs.

Could it be that our body has the ability to regenerate but just forgot how to communicate it? In an attempt to study this lost language, other scientists are sequencing the genome of axolotl salamanders . "You can do anything to it except kill it, and it will regenerate," says Gerald Pao, a postdoctoral researcher at the Salk Institute for Biological Studies, in La Jolla, CA. Salamanders and newts are the only vertebrates that can grow entire organs and replacement limbs as adults.

Biologist David Gardiner, also working on the project, believes regeneration comes from a fundamental ability now lying dormant in mammals. Gardiner thinks the skill can reawakened with some genetic nudging. He told Technology Review, "Most of the tissue in our arm regenerates; it's just the arm that doesn't regenerate," he says. "What's missing is how you coordinate a response to get an integrated structure." See Gardiner's team at work here.