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REVIEW ARTICLE
Year : 2012  |  Volume : 4  |  Issue : 1  |  Page : 11-14

Stem cells: Role in medical and dental therapies


Department of Oral Medicine Diagnosis and Radiology, Padamshree Dr. D. Y. Patil Dental College and Hospital, Pimpri, Pune, India

Date of Web Publication10-Sep-2012

Correspondence Address:
Sumit Bhateja
A-3, Flat No. 204, Dwarka Lords, Shivar Chowk, Pimple Saudagar, Pune (Maharashtra) – 27
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0975-8844.99876

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  Abstract 

Recent exciting new discoveries place dental professionals at the forefront of helping their patients benefit from potentially life-saving therapies derived from a patient's own stem cells obtained from deciduous or permanent teeth. The great hope is that suitable stem cells, produced in large quantities through cell culture methods and injected into failing tissues and organs, will produce fresh, replacement cells to take over from lost or damaged ones. This ability to grow and regenerate tissues is the focus of the emerging field of ­personalized medicine which uses a patient's own stem cells for biologically compatible therapies and individually tailored treatments. This review focuses on the role of oral physicians in the recovery and use of the stem cell in both dental and medical regenerative therapies.

Keywords: Regenerative medicine, replacement cells, stem cells, transplantation


How to cite this article:
Bhateja S. Stem cells: Role in medical and dental therapies. J Orofac Sci 2012;4:11-4

How to cite this URL:
Bhateja S. Stem cells: Role in medical and dental therapies. J Orofac Sci [serial online] 2012 [cited 2017 Sep 22];4:11-4. Available from: http://www.jofs.in/text.asp?2012/4/1/11/99876


  Introduction Top


We now stand at the threshold of a potential revolution in medical treatment for diseases and disorders in which organs stop working properly. At present, some conditions, such as heart, kidney and liver disease, can be treated by transplantation of an organ from another person. But demand for donor organs is far outstripping supply and the failure rate of such surgery is quite high, mainly due to the tissue rejection. It is now known that adult stem cells taken from one area of the body can be transplanted into another area and grown into a completely different type of tissue. [1]

The therapeutic promise of stem cells has generated great excitement in recent years as a potential biological treatment for oral and dental diseases. Several types of human dental stem cells have been identified and characterized and several companies are now offering services to preserve dental stem cells for future therapeutic use. In addition, the reprogramming of adult cells to a very early stage in their development (induced pluripotent stem cells) may lead to future opportunities to use these cells for oral and dental therapies. [1]


  What is a Stem Cell? Top


The term stem cell was proposed for scientific use by Russian histologist Alexander Maksimov in 1908. [2],[3] The stem cells are defined as clonogenic unspecialized cells capable of both self-renewal for long periods and multiline age differentiation, contributing to regenerate specific tissues. Stem cells in the developing tissues give rise to multiple specialized cell types that make up the heart, lung, skin, and other tissues. Stem cells are the master cells of the body and they are of two major types: embryonic and adult stem cells. [4] One embryonic stem cell has the potential to differentiate into all 220 types of specialized cells that make up the human body. Adult stem cells are responsible for the regeneration and replacement of tissue damaged by disease or injury. The two properties of stem cells that make them different from any other specialized cells in the body are: self renewal - the ability to go through numerous cycles of cell division while maintaining their undifferentiated state and differentiation - the ability to form into a specialized cell type. Another unique property of stem cells is their ability to grow in vitro - outside of the body in a laboratory. [3],[4]

Embryonic stem cells

Embryonic stem cells are the result of the fertilization of an egg by a sperm. Cells produced by the first few divisions of the fertilized egg are totipotent. At about the 5 th day, the cells become a blastocyst, an early stage embryo that is made up of 50-150 cells. Pluripotent stem cells are those embryonic stem cells that are harvested after the fifth day from the inner mass of this blastocyst. These pluripotent stem cells differentiate into any of the three types of cells that derive the germ layers: ectoderm, endoderm, and mesoderm. These stem cells are then called multipotent or adult stem cells and form around day 14. [3]

After 20 years of research, there are no approved treatments or human trials using embryonic stem cells. Their tendency to produce teratomas and malignant carcinomas, causing transplant rejection, and forming wrong kind of cells are just a few hurdles that embryonic stem cell researchers still face. [2],[3],[4]

Adult stem cells

Adult stem cells are usually designated according to their source and their potential. Adult stem cells are multipotent because their potential is normally limited to one or more lineages of specialized cells. However, a special multipotent stem cell that can be found in bone marrow and dental pulp is called the mesenchymal stem cell and can produce different cell types: bone, cartilage, fat, muscle, and connective tissues. However, a number of recent studies show that stem cells from one area may be manipulated to grow into cell types of a completely different tissue. This ability is called transdifferentiation or plasticity, and different types of adult stem cells have varying degrees of plasticity. Adult stem cells look like any other cell and are found diffusely spread throughout the body buried deep in tissue and organs of the body. Stem cell markers are surface glycoproteins called receptors that have the capability of selectively binding or adhering to other "signaling" molecules. Use of these stem cell markers allows researchers the ability to identify and separate the stem cells from the surrounding cells.

The adult stem cells can be recovered from the following: [5],[6]

  • Bone marrow derived mesenchymal stem cells
  • Adipose derived adult stem cells
  • Umbilical cord stem cells
  • Amniotic fluid-derived stem cells
  • Induced pluripotent stem cells derived from epithelial cells
  • Dental stem cells


The "dental stem cells" are the most accessible stem cells. They are isolated from the dental pulp of healthy tooth both primary and permanent teeth, periodontal ligament including the apical region of developing teeth, and other tooth structures. Craniofacial stem cells, including dental stem cells, originate from neural crest cells and mesenchymal cells during development [1] [Table 1]. The most accessible stem cells in children are from the oral cavity. For deciduous teeth, the best candidates are canine and incisors with the presence of healthy pulp. In children, other sources for easily accessible stem cells are supernumerary teeth, mesiodens, over-retained deciduous teeth associated with congenitally missing permanent teeth, and prophylactic removal of deciduous molars for orthodontic indications. Adolescents have two excellent opportunities for banking their stem cells from extracted bicuspid teeth for orthodontic treatment and wisdom teeth. The follicular sac of an unerupted tooth may also prove to be a valuable source for stem cells. [1]
Table 1: Stem cells in tooth tissues

Click here to view


The remarkable characteristic of the periodontal ligament is its ability to regenerate and repair virtually every other tissue type that comprises the periodontium. Undifferentiated mesenchymal cells of the periodontal ligament can differentiate into osteoblasts, chondrocytes, and adipocytes. Pulpectomies on vital pulps is another accessible means to collect viable stem cells. Other sources of stem cells accessible from the oral cavity during oral surgical procedures are alveolar bone, periosteum, buccal mucosa, gingival, and muscle. [7],[8],[9],[10]

Banking stem cells from teeth

Tooth-derived stem cells are readily accessible, and provide an easy and minimally invasive way to obtain and store stem cells for future use. Banking teeth and tooth-derived stem cells is a reasonable and simple alternative to harvesting stem cells from other tissues requiring invasive surgical procedures, and does not pose the ethical problems associated with embryonic stem cell harvesting. Cryopreservation is a process where cells or whole tissues are preserved by cooling to low sub-zero temperatures, such as (typically) −196°C (the boiling point of liquid nitrogen). At these low temperatures, any biological activity, including the biochemical reactions that would lead to cell death, is effectively stopped. [11]

How stem cells are extracted from banked tissue (Tooth)

Dental stem cells are preserved within the native tissue that was recovered at the time of the planned dental proce­dure. At the processing facility, the teeth are cracked open and the pulpal tissue containing the dental stem cells is col­lected, washed, processed, tested for cell viability, and then cryopreserved. When needed, the cryopreserved sample will be re­moved from the liquid nitrogen and the tissue will go through a thawing process. This tissue can either be digested enzymatically and placed into a cell sorter or depending on the size and quantity of tissue placed into a growth medium where the stem cells are allowed to grow into colonies. These colonies are characterized, and specific colonies are separated and allowed to continue to expand to the required number of cells indicated by the planned regenerative therapy protocol. [12]


  Stem Cells in Medicine Top


Application of regenerative medicine technology may offer new therapies for patients with injuries, end-stage organ failure, or other clinical problems. [Figure 1] shows various applications of stem cell therapy. Currently, patients suffering from diseased and injured organs can be treated with transplanted organs. However, there is a shortage of donor organs that is worsening yearly as the population ages and new cases of organ failure increase. Scientists in the field of regenerative medicine and tissue engineering are now applying the principles of cell transplantation, material science, and bioengineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues. The stem cell field is a rapidly advancing aspect of regenerative medicine as well, and new discoveries here create new options for this type of therapy. Stem cell-based therapies are being investigated for the treatment of many conditions, including neurodegenerative conditions such as Parkinson's disease, multiple sclerosis, liver disease, diabetes, cardiovascular disease, autoimmune diseases, musculoskeletal disorders, and for nerve regeneration following brain or spinal cord injury. The mesenchymal stem cells found in teeth may be beneficial for the treatment of neurodegenerative diseases and the repair of motor nerves following stroke or injury. This exciting research will lead to future treatment options that allow muscles to repair themselves following injury, such as the muscle damage that occurs after a heart attack or the structural damage that occurs following a knee injury. [1],[3] Drugs are being applied directly to human cells and this will provide more relevant data than drug testing on animals. [10]
Figure 1: Potential applications/uses of stem cell therapy

Click here to view



  Stem Cells in Dentistry Top


In the year 2003, Dr. Songtao Shi, a pediatric dentist, discovered baby tooth stem cells by using the deciduous teeth of his 6-year-old daughter; he was luckily able to isolate, grow, and preserve these stem cells' regenerative ability, and he named them as Stem cells from Human Exfoliated Deciduous teeth (SHED). [9] Stem cells and stem cell therapies will emerge to become an important aspect in the everyday practice of dental professionals. Adult stem cells may be used to regenerate bone and correct oral and craniofacial defects. Both in vitro studies and in vivo research in animal models have shown that tooth-derived adult stem cells can be used to regrow tooth roots in the presence of proper growth factors and a biologically compatible "scaffold." Regenerative therapy is less invasive than surgical implantation, and early animal studies suggest comparable results in strength and function of the biological implant as compared to a traditional dental implant. Stem cells extracted from the dental pulp of a third molar could be harvested, then directly implanted into the pulp chamber of a severely injured tooth. The goal is to regenerate the pulp inside the damaged tooth, preventing the need for endodontic treatment. Stem cells derived from the periodontal ligament may offer promise for regenerating the periodontal ligament and other supporting structures of the periodontium that have been destroyed by gingival and periodontal disease, with an alternative approach to traditional clinical therapies. Tissue-engineered bone grafts will be useful for practitioners in all of the dental specialties. Future tissues may also include engineered temporomandibular Joint (TMJ) joints and cranial sutures, which would be especially helpful to craniofacial and oral maxillofacial surgeons. [4],[13]


  Ethical Issues Related to Use of Stem Cells Top


Stem cell research has political, ethical, social, and legal issues, creating challenges for regulatory bodies, policy makers, and scientists, as they traverse their way through a tangled web of regulations and moral proselytizing. Stem cell research raises a number of such issues, which seem to fall naturally into two groups:

  1. Issues surrounding the origins of stem cells, in particular, the use of embryo stem cells. Even if it is assumed or determined that the source embryos would never have been enabled to develop as individuals, the use of such tissues does raise assumptions about the status of embryos, which have to be addressed.
  2. Issues relating to the use of stem cell tissue. In general, the issues are similar to those relating to organ donation and focus on the need for appropriate regulation.


In its entirety, medical science is concerned with interventions, whether preventive, therapeutic, surgical, emergency, or aimed at improving quality of life and recommending healthy lifestyle choices. [14]


  Conclusion Top


Virtually every tissue in the body contains some type of stem cell. From here arose the idea of medical and specifically dental cell based stratergies for tissue repair. The focus of stem cell research as it applies to dentistry is on facial reconstruction. Recent findings and scientific research supports the use of these very powerful mesenchymal stem cells found within teeth and other accessible tissue harvested from the oral cavity for use in regenerative medicine. While we can see the promise of human stem cell therapies for the future, dentists should know how important it is to harvest and store these mesenchymal stem cells, making these opportunities available to their child, adolescent, and adult patients for future regenerative therapies.

 
  References Top

1.Reznick JB. Stem Cells: Emerging medical and dental therapies for the dental professional. Dent Town Mag 2008;9:42-50.  Back to cited text no. 1
    
2.Becker AJ, McCulloch EA, Till JE. Cytological demonstration of the clonal nature of spleen colonies derived from transplanted mouse marrow cells. Nature 1963;197:452-4.  Back to cited text no. 2
    
3.The health council of the Netherlands report on stem cells for tissue repair. Research on therapy using somatic and embryonic stem cells, June 2002. Available from: http://www.gr.nl/pdf.php?1D=429;US NIH, Stem cells: A primer September 2002. Available from: http://www.nih.gov/news/stemcell/primer.htm [Last accessed on 2011 Sept 07].  Back to cited text no. 3
    
4.Casagrande L, Mattuella LG, de Araujo FB, Eduardo J. Stem cells in dental practice: perspectives in conservative pulp therapies. J Pediatric Dent 2006;31:25-7.  Back to cited text no. 4
    
5.Ghada KA. Dental pulp stem cells, a new era in tissue engineering. Smile Dent J 2009;2:23-8.  Back to cited text no. 5
    
6.Gronthos S, Graves SE, Ohta S, Simmons PJ. The STRO-l+ Fraction of adult human bone marrow contains the osteogenic precursors. Blood 1994;84:4164-73.  Back to cited text no. 6
    
7.Gronthos S , Brahim J, Li W, Fisher LW, Cherman N, Boyde A, et al. Stem cell properties of human dental pulp stem cells. J Dent Res 2002;81:531-5.  Back to cited text no. 7
    
8.Iohara K. Side population cells isolated from porcine dental pulp tissue with self-renewal and multipotency for dentinogenesis, chondrogenesis, adipogenesis, and neurogenesis. Stem Cells 2006;24:2493-503.  Back to cited text no. 8
    
9.Miura M, Gronthos S, Zhao M, Lu B, Fisher LW, Robey PG, et al. SHED: stem cells from human exfoliated deciduous teeth. Proc Natl Acad Sci USA 2003;100:5807-12.  Back to cited text no. 9
    
10.Siminovitch L, McCulloch EA, Till JE. The distribution of colony-Forming cells among spleen colonies. J Cell Physiol 1963;62:327-36.  Back to cited text no. 10
    
11.Ikeda E, Tsuji T. Growing bioengineered teeth from single cells: potential for dental regenerative medicine. Expert Opin Boil Ther 2008;8:733-44.  Back to cited text no. 11
    
12.Mao JJ. Stem cells and the future of dental care. NY State Dent J 2008;74:20-4.  Back to cited text no. 12
    
13.Daquino R, De Rosa A, Laino G, Caruso F, Guida L, Rullo R, et al. Human dental pulp stem cells: from biology to clinical applications. J Exp Zool Mol Dev Evol 2008;310B:408-15.  Back to cited text no. 13
    
14.Longstaff H, Schuppli CA, Preto N, Lafreniere D, McDonald M. Scientists perspectives on the ethical issues of stem cell research. Stem Cell Rev 2009;5:89-95.  Back to cited text no. 14
    


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Introduction
What is a Stem Cell?
Stem Cells in Me...
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