Banking Stem Cells from “Baby” Teeth
Instead of discarding exfoliated deciduous teeth (or “baby teeth”), salvaging the living stem cells within the pulp and storing them in a professional dental stem cell bank for future use may be a better option. To explain the rationale, a brief discussion of stem cells is warranted.
What Are Stem Cells?
Fertilization of the egg by the sperm yields the fertilized egg or zygote, which has genetic contributions from the mother and the father. This one cell has unlimited potential, or it is totipotent, and undergoes numerous cell divisions to eventually yield the trillions of cells comprising the adult. As development progresses from the zygote to the embryo to the fetus and to the adult, the genetic potentials of the cells change, as genes in some cells are inacti- vated and in other cells remain active. This selective activation/inactivation of genes in par- ticular cell populations is responsible for cell differentiation and specialization, so that spe- cific populations of cells acquire particular characteristics - e.g., some cells form muscle tis- sue, others form bone tissue, etc.
Stem cells have two unique characteristics: (1) they are “immortal” and can grow continuous- ly and, (2) upon proper stimulation by signaling molecules, they can be induced to differenti- ate into specific cell types. The extent of this plasticity to form specialized cell types varies for different types of stem cells. According to their potential, stem cells are classified as: (a) totipotent - a stem cell that possesses the potential to produce all the different tissues and specialized cell types that comprise an entire adult; the zygote is a totipotent stem cell; (b) pluripotent - a type of stem cell that can differentiate into nearly all (but, not all) types of cells in the adult; such stem cells when isolated from the multicellular embryo are termed embryonic stem cells and when isolated from the gonads of a fetus are termed fetal germ cells; (c) multipotent - a type of stem cell that can differentiate into several types of cells; for example, hematopoietic stem cells isolated from bone marrow produce the various white blood cells, red blood cells, and platelets in the adult. Multipotent stem cells are a type of an adult stem cell.
As cells progress from totipotency to pluripotency to multipotency their plasticity is reduced, as they become more restricted in function and structure. Multipotent stem cells are isolated from tissues, such as bone marrow, skin, and fat, of an adult, and, thus, ethical issues in- volved with using cells derived from human embryos or fetuses are non-existent. In an adult, these multipotent stem cells function to renew cell populations, to repair damaged, and to maintain tissue homeostasis.
Uses of Stem Cells
Multipotent stem cells are used in therapies to treat diseases and to regenerate damaged tis- sues. For example implantation of neural stem cells into the brain is used to treat Parkinson disease and into the spinal cord to repair spinal cord injuries; cartilage stem cells are used to repair joints damaged by injury or arthritis.
Stem Cells in Teeth
Mesenchymal stem cells, a type of multipotent stem cell, are found in the pulp region of hu- man exfoliated/extracted deciduous teeth. Although exfoliated teeth essentially are a waste product, their mesenchymal stem cells have a potential therapeutic potential as they can be used in regenerative procedures. Such stem cells have the potential to produce bone, muscle, cartilage, liver, neural cells, and aggregates that synthesize insulin, to treat type 1 diabetes. Thus, use of mesenchymal stem cells obtained from deciduous teeth have great potential in medical therapies.
Of the various sources for stem cells, dental stem cells are the most readily accessible with potential for use in medical therapies. Using one’s own stem cells in a therapeutic procedure, eliminates concerns about immunologic reaction and thereby the need for immunosuppressive drugs. As one ages, the body’s stem cells have slower regenerative properties. Stem cells ob- tained from “baby” teeth grow faster and are more numerous than those from adult teeth.
Banking Dental Stem Cells
The process for banking dental stem cells is not performed by the dentist. Rather, a dentist extracts the deciduous tooth when one third of the root remains, as the internal mesenchy- mal stem cells are still viable. The dentist preps the tooth with the materials furnished by the specific dental stem cell bank. ships the tooth overnight to the appropriate laboratory, in which the cells are extracted from the tooth and grown in culture to generate billions of cells, which are cryopreserved until needed.
Banking dental mesenchymal stem cells offers regenerative therapies that differ from that available by banking umbilical cord hematopoietic stem cells. The later stem cells are used in blood-based therapies to regenerate blood and bone marrow for cancer patients. Most com- monly, these hematopoietic stem cells are used to regenerate the immune system of patients treated for leukemia. Today, umbilical cord hematopoietic stem cells are used to treat 78 dif- ferent diseases. The Food and Drug Administration (FDA) has approved umbilical cord blood- derived hematopoietic stem cells for specific usages.
Uses of Dental Stem Cells
As yet, the FDA has not approved uses for other stem cells, including those of dental mes- enchymal stem cells. At this point, the applicability of dental mesenchymal stem cells in re- generative therapy is speculative. However, due to their capacity to differentiate into sever- al cell types, dental mesenchymal stem cells have strong applicability in regenerative therapy in dentistry. Dr. Jade Miller, president of the American Academy of Pediatric Dentistry, stated that dental mesenchymal stem cells may be used to repair cavities, fix a tooth damaged from periodontal disease or bone loss, or even grow a tooth instead of using dental implants.