Despite approaches in regenerative medicine using stem cells, bio-engineered scaffolds, and targeted drug delivery to enhance human tissue repair, clinicians remain unable to regenerate large-scale, multi-tissue defects in situ. The study of regenerative biology using mammalian models of complex tissue regeneration offers an opportunity to discover key factors that stimulate a regenerative rather than fibrotic response to injury. For example, although primates and rodents can regenerate their distal digit tips, they heal more proximal amputations with scar tissue. Rabbits and African spiny mice re-grow tissue to fill large musculoskeletal defects through their ear pinna, while other mammals fail to regenerate identical defects and instead heal ear holes through fibrotic repair. This Review explores the utility of these comparative healing models using the spiny mouse ear pinna and the mouse digit tip to consider how mechanistic insight into reparative regeneration might serve to advance regenerative medicine. Specifically, we consider how inflammation and immunity, extracellular matrix composition, and controlled cell proliferation intersect to establish a pro-regenerative microenvironment in response to injuries. Understanding how some mammals naturally regenerate complex tissue can provide a blueprint for how we might manipulate the injury microenvironment to enhance regenerative abilities in humans.

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Published in Stem Cells Translational Medicine, v. 7, issue 2, p. 220-231.

© 2017 The Authors

This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.

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A.W.S. is supported by the National Science Foundation (NSF) and the Office for International Science and Engineering (OISE) (IOS-1353713) and the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS—NIH) (R01AR070313).

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