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Stem Cells from Human Exfoliated Deciduous Teeth
Stem cells obtained from human exfoliated deciduous teeth or (SHED stem cells) are a relatively new discovered multipotent, postnatal stem cell. Human exfoliated deciduous teeth or baby teeth, are the first set of temporary teeth that form during embryonic development and erupt through the gums once an individual has reached infancy. Similarly to Mesenchymal stem cells, SHED stem cells can differentiate into many types of tissues. Since 2001, there have been multiple experiments with SHED stem cells to determine the rate of differentiation, comparing the different types of stem cells such as Dental Pulp stem cells and Mesenchymal stem cells. Experiments have discovered similar results between SHED stem cell and Mesenchymal stem cell differentiation.

Current Research
Within the last two years there have been many research groups conducting experiments to test the differentiation ability of SHED stem cells in general wound healing, regeneration of bone and restoration of neurons in the brain. The overall consensus of each group was that SHED stem cells differentiated similarly to other postnatal stem cells and embryonic acquired stem cells.

Yamada et al. experimented with SHED stem cells’ ability to regenerate bone and discovered that SHED stem cells differentiated quicker then Mesenchymal stem cells. They observed SHED stem cells producing 2% more bone growth then Mesenchymal stem cells. The percentages between each stem cell were 52.8% in canine mesenchymal stem cells, 61.6% in canine dental pulp stem cells, and 54.7% in puppy deciduous teeth stem cells after 8 weeks. The 2% increase in bone growth was calculated by simply subtracting the canine mesenchymal stem cell percentage (52.8%) from the puppy deciduous teeth stem cell percentage (54.7%).

Nishin et al. in 2011, discovered when SHED stem cells were introduced to a wound, the human hemagglutinin (HA) binding protein would surround the PKH26-positive cells, displaying increased HA expression. The HA expression values for each stem cell were 2342.07 ng/mg in human mesenchymal stem cells and 2314.85 ng/mg in SHED stem cells. These values were significantly higher in human mesenchymal stem cells and SHED stem cells when compared with the control at days 7 and 14.

Using flow cytometric analysis, Nourbakhsh et al. revealed SHED stem cells rapidly expressed nestin and b-III tubulin, and later expressed intermediate neural markers, suggesting that SHED stem cells can differentiate into neural cells. STRO-1 and CD146 are stromal cell markers and are used to count the amount of differentiated SHED stem cells by the use of immunofluorescence. 96.5% of STRO-1 and 49.0% of CD146 were expressed as stromal neural markers during in vitro techniques, expanding SHED stem cells. Although more experiments and research are required, SHED stem cells will be a breakthrough therapy for patients with neurological diseases, which right now do not have a cure such as Parkinson’s disease.

Clinical Use
Currently, SHED stem cells have not been accepted as a formal treatment in humans, however there have been significant discoveries enabling scientists to save endangered animal species using SHED, Mesenchymal and other types of stem cells.

The Pros of SHED Stem Cell Treatment
SHED stem cells treatment’s unique ability to pose no danger to life for its collection is a major contributor to further SHED stem cells’ research. Currently, there is much discussion about the ethics of modern day embryonic stem cells and how they are collected. Embryonic stem cells are acquired from either an embryo, umbilical cord or from fluids surrounding the embryo. Postnatal stem cells including SHED differ from embryonic stem cells because they can be collected from hair follicles, brain, bone marrow, skin, skeletal muscle, dental pulp and exfoliated teeth. Postnatal stem cells pose an alternative to the undesirable collection of embryonic stem cells.

The Cons of SHED Stem Cell Treatment
Even with all the benefits that SHED stem cells pose for medicine, there are still some negative effects. When SHED stem cells are used in wound healing, scarring still takes place along with imperfect wound healing. When SHED stem cells are used for the regeneration of mandible bone, there was irregular growth or incorrect bone formation. Neuron differentiated SHED stem cells pose even more problems because of the vast unknown information on the central nervous system and brain. SHED stem cells still lack two proteins that mesenchymal stem cells can produce and although they do not have clear negative effects in the lab experiments, there is no way that SHED stem cells can be used on neurons in the near future until further research is done.

Acknowledgements
I would like to thank both of my group members Alazar Ayele and Jacob Ratliff for their contributions to this article’s structure. Secondly, I would like to thank Jennifer White, Garrison Wilson, Cameron Perry and Ryan Hanlon for not only asking questions that lead to the input of more information, but also for reading over my article for general corrections.