Written by: Noelle A. Koo (12th grade / Ashburn, VA USA)
Planarians have been deemed as promising model organisms within the fields of regenerative medicine and bioengineering due to their remarkable regenerative capabilities and mechanisms. Planarians belong to the phylum Platyhelminthes, class Turbellaria, and order Seriata, and are often found in freshwater ecosystems. A facilitating factor for many degenerative diseases such as neurodegenerative and cardiovascular diseases is the inability for specific cells and tissues to regenerate. Therefore, studying the regenerative capabilities of planarians have allowed researchers to gain insights into the mechanisms through which these organisms are able to regenerate so quickly and efficiently.
A large part of the reasons why planarians are able to regenerate (especially post-injury) so efficiently is due to the pluripotent stem cells that compose these organisms. More specifically, regeneration in planarians is primarily facilitated by planarian adult stem cells (pASCs) which are also known as neoblasts. Neoblasts are undifferentiated cells that are present within many mammalian organisms in the tissue below the muscle layers and around the surface of organs. Planarian neoblasts are regarded as adult pluripotent stem cells, although more research is ongoing to further understand the molecular roles these cells play in regeneration.
In this research paper, the advantages of planarians as a model for stem cell biology and regeneration are outlined (Gentile, et. Al):
"Planarians can regenerate any body part (even the central nervous system) from small pieces within a few days"
"Planarians contain a large number of adult stem cells, some of which, if not all, are pluripotent"
"Planarians are easy and cost-effective to maintain, and can be grown to large populations"
"Many planarian proteins are significantly similar to human proteins"
"RNA interference can be efficiently carried out in planarians by feeding, injecting, or soaking with solutions of double-stranded RNA"
"The genome of Schmidtea mediterranea has been sequenced; transcriptome datasets are being generated to facilitate understanding of the genetic regulation of planarian regeneration"
Therefore, it can be seen that the regenerative abilities of planarians enables these organisms to effectively model how optimal cell proliferation should occur and greater study of these organisms will allow for a molecular understanding of the specific mechanisms that drive the regeneration which may contribute to future regenerative medicine studies.
Research Paper citation:
Gentile, L., Cebria, F., & Bartscherer, K. (2010). The planarian flatworm: An in vivo model for stem cell biology and nervous system regeneration. Disease Models & Mechanisms, 4(1), 12-19. doi:10.1242/dmm.006692
Link to paper: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3014342/
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