Cells4Life!!! It’s Shark

The human dentition is a typical diphyodont mammalian system with tooth replacement of most

positions. However, after dental replacement and sequential molar development, the dental lamina

undergoes apoptosis and fragments, leaving scattered epithelial units (dental lamina rests; DLRs).

Adult human DLRs are presumed to be dormant epithelia with low regeneration potential. However, we show that these tissues not only contain a small proportion of proliferating cells (as determined by Ki67 and PCNA), but also express a number of common dental stem cell markers (Sox2, Bmi1, -catenin, and PH3), as seen in many vertebrates that actively and continuously regenerate their dentition.

We compared these human tissues to the dental lamina of sharks that regenerate their teeth throughout their lives, demonstrating that human tissues have the ability to regenerate in ways that have yet to be discovered. We also examined human ameloblastoma cases in order to better understand the proliferative characteristic of dental lamina resting.

Ameloblastomas are assumed to derive from aberrant lamina rests that undergo changes, which are not well understood, to form a benign tumour. We suggest that dental lamina rests can offer a potential source of important dental stem cells for future dental regenerative therapy. The combined developmental genetic data from the shark dental lamina and ameloblastoma may lead to the development of novel methods to utilise these rested populations of adult lamina stem cells for controlled tooth replacement in humans.

The dental lamina of a shark serves as a paradigm for active and high-yield tooth regeneration

Due to their extraordinarily quick tooth creation and continual de novo tooth regenerative ability, sharks are an attractive new model for investigations of tooth formation and regeneration. Recent genomic advancements in elasmobranchs have begun to expand our understanding of these species, setting the door for future advances in comparative developmental and genomic biology. As a result of these developmental models' comparative potential to inform the evolution and development of mammalian systems, translational breakthroughs will emerge directly from our understanding of these uncommon model species.