Regeneration of Amputated Zebrafish Fin Rays from De Novo Osteoblasts

Abstract

SUMMARY Determining the cellular source of new skeletal elements is critical for understanding appendage regeneration in amphibians and fish. Recent lineage-tracing studies indicated that zebrafish fin ray bone regenerates through the de-differentiation and proliferation of spared osteoblasts, with limited if any contribution from other cell types. Here, we examined the requirement for this mechanism by using genetic ablation techniques to destroy virtually all skeletal osteoblasts in adult zebrafish fins. Animals survived this injury and restored the osteoblast population within two weeks. Moreover, amputated fins depleted of osteoblasts regenerated new fin ray structures at rates indistinguishable from fins possessing a resident osteoblast population. Inducible genetic fate-mapping confirmed that new bone cells do not arise from de-differentiated osteoblasts under these conditions. Our findings demonstrate diversity in the cellular origins of appendage bone, and reveal that de novo osteoblasts can fully support the regeneration of amputated zebrafish fins.

Inducible genetic system for the axolotl

“…Understanding how salamanders regenerate limbs should provide critical insight into efforts to stimulate these processes in vertebrates that do not regenerate limbs, yet the list of modern molecular genetic tools that can be applied to salamanders is currently very short. Other model systems with a much more sophisticated experimental toolkit, such as zebrafish, have provided valuable clues to the molecular underpinnings of vertebrate appendage regeneration (2)(3)(4)(5)(6)(7)(8)(9)(10)(11). However, fin regeneration in teleost fish (such as zebrafish) is not completely analogous to limb development or regeneration.…”

Adenosine enhances progenitor cell recruitment and nerve growth via its A2B receptor during adult fin regeneration

“…A major issue that remains is how to control the cellular neighbourhoods in order to promote the differentiated/progenitor transition in vivo, and in this context, epimorphic regeneration in amphibians and fish provides relevant models of integrated regeneration [15,16]. Although it seems that any type of differentiated cell is able to participate in blastema formation [6,[53][54][55][56][57], only a few types will respond to injury by progressing towards progenitor identity. The lesion must induce a response that is differentially sensed by stump cells.…”

Electric fish: new insights into conserved processes of adult tissue regeneration

“…Studies on zebrafish regeneration are contributing extensively to our current understanding of regeneration mechanisms to replace different cell and tissue types. Indeed, the ability to carry out lossand gain-of-function experiments in combination with genetic screens and in vivo cell tracing is increasing the identification of regulatory factors and progenitor cells involved in zebrafish regeneration (Tanaka and Reddien, 2011;Sánchez Alvarado and Tsonis, 2006;Singh et al, 2012). Even so, the ability of adult zebrafish to fully repair and restore all damaged or lost tissues, organs and limbs is limited.…”

“…For example, generation of reliable cell markers have led to recent findings that resident, tissuespecific stem cells also respond to injury and contribute to blastema formation in some vertebrate species (Li et al, 2007;Morrison et al, 2006;Poss et al, 2003;Singh et al, 2012;Weber et al, 2012). Hence, the extent to which cell dedifferentiation versus stem cell activation occurs in response to injury in vertebrates warrants further investigation.…”

“…Specifically, in vivo cell tracing experiments in urodele amphibians have shown that mature cells including muscle fibers can dedifferentiate, proliferate and enter the blastema (Stocum, 1995;Echeverri et al, 2001;Brockes and Kumar, 2002;Nye et al, 2003;Nechiporuk and Keating, 2002;Tanaka and Reddien, 2011). Similarly, the robust regenerative capacity of zebrafish to regrow amputated fins, heart and neural tissue such as the spinal cord and retina is suggested to depend on dedifferentiation of cells near the amputation site by studies using transgenesis, loss-and gain-of-function technology, and cell labeling methodology (Tanaka and Reddien, 2011;Singh et al, 2012;Poss et al, 2003;Poss, 2010).…”