SCIENCE STORYTELLING
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Breaking the regeneration Barrier Could we someday be able to regenerate organs or tissues like house lizards? by Jianyi lee
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N like a nuisance. If you pay closer attention, you will notice that lizards can voluntarily shed their tails and grow a replacement tail soon after. Lizards are among the many species within the animal kingdom that possess the ability to regenerate lost or damaged appendages (Figure 1 naturally occurring prowess is part of an evolutionarily acquired trait that enables the animal to escape threatening encounters with predators. One may wonder then, why do humans have limited capabilities to regenerate damaged organs or tissues after an injury? Recently, evidence from skin shedding African spiny mice suggests that mammals actually have a higher capacity to regenerate than previously thought1 the mystery behind how some of these model organisms regenerate is at the forefront of Photo: Deseret News Figure 1: Limb regeneration in newts.
injury and diseases.
Quite simply put, regeneration is the ability of an adult organism to fully replace damaged tissues and organs by growing or remodeling existing tissues2 to answer four main questions. First, what determines the regenerative potential of an organism? Second, how does the organism control and terminate the regenerative program appropriately? Here, I present a minimalist view of common themes in regeneration. by multiple factors. In highly regenerative species, certain genetic pathways or conserved genes are selectively activated during regeneration. Incremental changes in the expression of these genes into potential targets for therapy. In mammals, it is apparent that
“...mammals actually have a higher capacity to regenerate than previously thought.�
may be attributed to the fact that young tissues have more access to embryonic developmental programs that are required for regeneration as opposed to adults whose tissues have kept these programs dormant for long periods of time. Age-related drop in regenerative capacity is particularly evident in the brain, pancreas and skeletal muscle, therefore explaining why many aging diseases are associated with these tissues2. One can address the regeneration problem by understanding the origins of the new cells that reconstitute
require the de-differentiation or trans-differentiation of existing cells3 (Figure 2). New cell production from de-differentiation involves mature cells reverting back to a state where they are competent to become multiple cell types. During trans-differentiation, cells directly convert from one mature cell type to another. ISSUE 4 / 2012
