Marco Tatullo, Massimo Marrelli, Kevin M. Shakesheff, Lisa J. White
Physiology of Dental Pulp and Cell Function
Teeth develop through inductive signaling between epithelial and ectomesenchymal cells. An outer later of enamel is formed which covers the crown of the tooth which covers the root’s surface. There is an inner layer composed of dentin and the pulp core. The pulp core contains the “connective tissue, mesenchymal cells, neural fibres, blood vessels, and lymphatics.”
Teeth do not have the same regenerative abilities as seen in bone and have limited reparative capabilities. Teeth are vulnerable to environmental agents, mechanical damage, infection, and disease.
In response to damage, dental pulp stem cells produce odontoblasts that can reparative dentin support.
Isolation of Dental Pulp Stem Cells
Dental pulp stem cells can be isolated by subjecting the pulp to a collagenase dispase digest. Tension was added to digested tissue to generate single suspended cells. Colony-forming cells were also found in high numbers inside the dental pulp. When comparing the population size of stem cells isolated from adult teeth versus “exfoliated decidous” baby teeth, there was a higher frequency of cells in the baby teeth. Cells derived from baby teeth had a higher proliferation rate than cells extracted from adult teeth.
Regenerative Medicine Applications of Dental Pulp Cells
Dental Pulp Regeneration
Regenerative endodontics is the process of removing infected or necrotic tooth pulp and replacing it with regenerated healthy tissue that can rejuvenate teeth.
Tests done in mice revealed that human dental pulp stem cells had the ability to produce dentin-like structures that mimicked the structure of primary dentin.
Isolation of dental pulp stem cells lead to two significant tooth tissue engineering strategies; in vivo transplantation of stem cells and in vitro culture of stems on scaffolds that are then transplanted in vivo.
In Situ Pulp Regeneration
Nakashima’s research group was able to regenerate pulp and dentin using cultured porcine pulp cells. The expression of dentin sialophosphoprotein in the cultured three dimensional pellet confirmed that the dental pulp stem cells were specializing into odontoblasts.
Similar results demonstrating complete in situ pulp regeneration were achieved using canine pulp.
De Novo Pulp Regeneration
New pulp tissue can be regenerated in cases where the entire pulp is lost. To do this, pulp must be vascularized, new odontoblasts have to form on the existing dentinal wall of the root canal space, and new dentin must be formed by odontoblasts onto the existing dentin.