Prelude
This blog will relate the importance of proteomics analysis with mesenchymal stem cells in human teeth. Before going into depth of the relation between stem cells and the human teeth, let us learn about some background in proteomics, methods of proteomics analysis, stem cells and the dental anatomy.
What is Proteomics?
According to News Medical, “proteomics is the large-scale study of proteins, particularly their structures and functions.” The term “proteomics” was used to make an analogy with “genomics” (the study of genomes and genes) since 1997.
http://www.news-medical.net/health/Proteomics-What-is-Proteomics.aspx
Why pay attention to proteomics?
In undergraduate biology courses, emphasis was made on protein structures influences their functions. Furthermore, mRNA is not always translated into protein. In other words, the amount of protein produced depends on the mRNA being transcribed from a particular gene due to the physiological state of the cell [News Medical]. Proteomics became an interesting area to study and research because it gives us better understanding an organism, some protein-related diseases. We can study the conditions in which the mRNA for the protein is transcribed and then translated. We can also study the mechanisms on the post-translational modifications in which affects the proteins’ functions. In diseases, the study of proteomics can help compare the different proteins expressed in healthy and diseased cells and basing on the proteins expressed and the specific functions of the proteins, a hypothesis of the rise of the diseased cells may be formulated which can lead to specific targeting on the proteins via various treatments.
Methods on Proteomics Analysis:
- Immunoassays: ELISA- uses antibodies and colors to identify a protein of interest in a sample
If you are interested, read more here: https://www4.vanderbilt.edu/vapr/elisa
- Two-dimensional Gel Electrophoresis (2D- DIGE) [Figures on the results of 2D-DIGE in the The Significance of Stem Cells: Proteomic Analysis of Normal vs Deep Carious Dental Pulp portion below] – separates molecules in 1D electrophoresis first then separate them by a second property in a direction of 90 degrees from the first. The proteins that have two distinct properties will be shown on the gel effectively.
What are Mesenchymal Stem Cells (MSCs)?
According to the National Institutes of Health website, stem cells “have the remarkable potential to develop into many different cell types in the body”. Stem cells are unspecialized cells that can renew themselves and under certain physiological/ environmental conditions, they can be induced to become specific/differentiated cells. In this blog, we are concerned about stem cells in dental pulp. This means that we can extract stem cells from dental pulp into other tissues for tissue regeneration.
Read more here: http://stemcells.nih.gov/info/basics/pages/basics1.aspx
The Basic Human Dental-Tooth Anatomy
In this blog, we are focusing on the stem cells in the dental pulp. We will be looking at the protein analysis in normal vs deep carious dental pulp. A human tooth has its pulp chamber in the center of the tooth where all the connective tissue- blood vessels and cells- odontoblasts lie. The pulp is like “the heart” of the tooth, injury to the dental pulp may lead to tooth-death where the cell activity and their signaling processes that help with repairing of the tooth is disrupted. A normal dental pulp is a healthy tooth without caries whereas a deep carious dental pulp is a tooth which has caries where the tooth enamel and dentin has been degraded by the bacterial acid byproduct during their food (sugar) consumption. Just a fun fact: dental plaque- a biofilm found on our teeth surface are in fact colonizing bacteria trying to attach themselves on our teeth. So often when a person just had a sugary meal, more plaque tend to form on the teeth. If plaque builds up on the sides of the crown between the gums, this will lead to bone recession and thus gum recession and eventually lead to gum disease and periodontal disease. So it is important to floss and get those dental plaque out!
The Significance of Stem Cells:
Proteomic Analysis of Normal vs Deep Carious Dental Pulp
Ma et al. mentioned in their research paper that “human dental stem cells are generally applied in tissue and organ regeneration (1).” They carried out proteomic analysis of dental pulp stem cells (DPSCs) and carious dental pulp stem cells (CDPSCs) as they claimed that DPSCs are “ideal seed cells for tooth tissue regeneration, [and] can differentiate into functional odontoblasts in vivo when the tooth encounters external mild stimuli such as carious lesion, attition and abarsion…[but] the molecular mechanisms responsible for the biological differences between CDPSCs and DPSCs are still unclear (1).” In short, Ma et. al wanted to see what specific proteins play a role in stem cells in dental pulp that may help with dental tissue regeneration.
Before looking for the differences of proteins expressed in CDPSCs and DPScs, Ma et al. confirmed that CDPSCs has a higher proliferation rate than DPSCs by using the cell counting assay. The results were significant as P<0.01.
In order to better understand the changes in molecular mechanisms of DPSCs when there are deep caries that lead to the biological differences between DPSCs and CDPSCs, Ma et. al then analyzed the proteins expressed in DPSCs and CDPSCs by using 2D-DIGE.
Fig 3 and Fig 4.
2D-DIGE of CDPSCs (3A), DPSCs (3B) and standard proteome map (3C). Figure 4A and B shows the 18 different proteins expressed in CDPSCs and DPSCs. Ma et al. then selected proteins with functions of cell proliferation and differentiation: CCT2, stathmin and CLIC4.
CCT2: potential positive regulator of cell growth. Can also found in certain malignant tumors. The ability of CDPSCs to have a higher cell proliferation rate may be due to higher expression of CCT2.
Stathmin: involved in intracellular signaling pathways like cell proliferation, microtubule dynamics and activities (5). It was also suggested that stathmin promotes osteoblast differentiation. CDPSCs is more differentiated than DPSCs according to Ma et al. so the expression of this protein is expected to be higher in DPSCs.
CLIC4: found in transmembranes and intramembranes of cells. It is important for membrane trafficking, cell proliferation, differentiation and host defense. This can be evidence that there is an increased expression in CDPSCs due to bacterial infection.
Ma et al. isolated 3 proteins from the dental pulp stem cells that might be responsible for the biological differences between CDPSCs and DPSCs. Furthermore, these proteins are known to be involved with cell proliferation, differentiation, cell cytoskeleton and motility (8). So effort should be put into further studies on these proteins in order to help with dental tissue regeneration.
References
Ma. Dandan et. al. Proteomic Analysis of Mesenchymal Stem Cells from Normal and Deep Carious Dental Pulp. PLoS One, May 2014. Web. 6 Feb 2015.
Image: http://www.angelaharneydentistry.com/blog/post/tooth-anatomy.html