Dental pulp cells produce neurotrophic factors, interact with trigeminal neurons in vitro, and rescue motoneurons after spinal cord injury. (33/535)

Interactions between ingrowing nerve fibers and their target tissues form the basis for functional connectivity with the central nervous system. Studies of the developing dental pulp innervation by nerve fibers from the trigeminal ganglion is an excellent example of nerve-target tissue interactions and will allow specific questions regarding development of the dental pulp nerve system to be addressed. Dental pulp cells (DPC) produce an array of neurotrophic factors during development, suggesting that these proteins might be involved in supporting trigeminal nerve fibers that innervate the dental pulp. We have established an in vitro culture system to study the interactions between the dental pulp cells and trigeminal neurons. We show that dental pulp cells produce several neurotrophic factors in culture. When DPC are cocultured with trigeminal neurons, they promote survival and a specific and elaborate neurite outgrowth pattern from trigeminal neurons, whereas skin fibroblasts do not provide a similar support. In addition, we show that dental pulp tissue becomes innervated when transplanted ectopically into the anterior chamber of the eye in rats, and upregulates the catecholaminergic nerve fiber density of the irises. Interestingly, grafting the dental pulp tissue into hemisected spinal cord increases the number of surviving motoneurons, indicating a functional bioactivity of the dental pulp-derived neurotrophic factors in vivo by rescuing motoneurons. Based on these findings, we propose that dental pulp-derived neurotrophic factors play an important role in orchestrating the dental pulp innervation.  (+info)

The exact expression of glial fibrillary acidic protein (GFAP) in trigeminal ganglion and dental pulp. (34/535)

The expression in various cell types of peripheral tissues of glial fibrillary acidic protein (GFAP), first discovered as an intermediate filament specific for astrocytes, remains controversial owing to numerous reports of a wide distribution for GFAP-immunoreactivity in various cells. The present study employed immunohistochemistry to investigate the precise expression of GFAP in the dental pulp and trigeminal ganglion of adult rats and wild-type mice as well as GFAP-knockout mice. The exhibition of GFAP-immunoreactivity in the trigeminal ganglion was further examined by a reverse transcription polymerase chain reaction (RT-PCR) technique, and in situ hybridization histochemistry using a specific cRNA probe prepared by us. The immunoreaction for GFAP was recognizable in the axons, Schwann cells, and the fibroblasts in the dental pulp of rats and wild-type littermate mice. However, mice with null mutations in the GFAP gene remained immunoreactive for GFAP in all these locations. Intense GFAP-immunoreactivity was found in a small number of satellite cells in the trigeminal ganglion in all animals examined in this study. RT-PCR analysis demonstrated bands for the GFAP gene corresponding to the length expected from the primer design in the samples of trigeminal ganglion and dental pulp. In situ hybridization histochemistry also showed intense signals for GFAP mRNA in some satellite cells of the trigeminal ganglion, but never in the neurons. These data suggest that the GFAP-immunoreactive molecules in the pulpal axons and fibroblasts react non-specifically with the polyclonal antibody and are probably a closely related type of intermediate filament.  (+info)

Measurement of pulpal blood flow in dogs with nonradioactive colored microspheres. (35/535)

The viability of dental pulp depends largely on regional blood flow, as in other organs. Measurement of absolute pulpal blood flow (PBF) and comparisons with blood flow in other organs allow the prediction of microvascular regulation in dental pulp. In previous studies, PBF was measured in dogs mainly with radioactive microspheres. However, this established technique is inaccessible to many investigators due to concerns over radiation safety and radioactive waste. To overcome these limitations, a new method has been introduced that involves the use of nonradioactive colored microspheres for measuring regional blood flow in the myocardium and in other organs in animals. However, no previous studies have investigated the use of this method to measure PBF in dogs. We attempted to determine whether blood flow in dental pulp, which comprises a small amount of the total tissue in dogs, could be measured using this technique by comparing the measured values with those for regional myocardial blood flow. Mean blood flow values were between 0.148 and 0.182 ml/min/g for dental pulp at four different sites and about 1.0 ml/min/g in regional myocardium. These values are comparable to those previously reported using radioactive microspheres. As nonradioactive colored microspheres safety permitted measurement of absolute PBF in dogs, this technique appears to be useful for research into microvascular blood flow in dental pulp.  (+info)

The effect of continuous intrusive force on human pulpal blood flow. (36/535)

The purpose of this study was to examine the effect of continuous intrusive force application on human pulpal blood flow (PBF). Recordings were made of 13 vital upper left central incisors in 13 healthy participants (experimental group, n = 8; control group, n = 5) who had clinically healthy tooth crowns and periodontal tissues. PBF was recorded by means of a laser Doppler flow meter (LDF) with an opaque rubber dam applied to the teeth. The basal blood flow in the pulp (BBFP) was compared during three observation periods: (1) before orthodontic archwire engagement; (2) during wire engagement (control group: no application of force; experimental group: continuous intrusive force of 0.5 N); and (3) after the removal of the wire. In the experimental group, brief intrusive forces (magnitude 0.5, 1.0, and 2.0 N) were applied to the incisal edge of the examined teeth to determine their effect on acute changes in PBF. The results obtained were as follows: (1) the BBFP in the experimental group was significantly reduced during the period of continuous intrusive force application (P < 0.05), which was followed by recovery after the removal of the wire. (2) Brief intrusive force produced a significant reduction of PBF (P < 0.05), but the reduction rate (percentage) did not differ significantly during the observation periods. The results indicate that the measurement technique shown in this study could detect PBF change produced by continuous orthodontic force application.  (+info)

Mice lacking monocyte chemoattractant protein 1 have enhanced susceptibility to an interstitial polymicrobial infection due to impaired monocyte recruitment. (37/535)

Monocyte chemoattractant protein 1 (MCP-1) is an important chemokine that induces monocyte recruitment in a number of different pathologies, including infection. To investigate the role of MCP-1 in protecting a host from a chronic interstitial polymicrobial infection, dental pulps of MCP-1(-/-) mice and controls were inoculated with six different oral pathogens. In this model the recruitment of leukocytes and the impact of a genetic deletion on the susceptibility to infection can be accurately assessed by measuring the progression of soft tissue necrosis and osteolytic lesion formation. The absence of MCP-1 significantly impaired the recruitment of monocytes, which at later time points was threefold higher in the wild-type mice than in MCP-1(-/-) mice (P < 0.05). The consequence was significantly enhanced rates of soft tissue necrosis and bone resorption (P < 0.05). We also determined that the MCP-1(-/-) mice were able to recruit polymorphonuclear leukocytes (PMNs) to a similar or greater extent as controls and to produce equivalent levels of Porphyromonas gingivalis-specific total immunoglobulin G (IgG) and IgG1. These results point to the importance of MCP-1 expression and monocyte recruitment in antibacterial defense and demonstrate that antibacterial defense is not due to an indirect effect on PMN recruitment or modulation of the adaptive immune response.  (+info)

Induction of dental pulp stem cell differentiation into odontoblasts by electroporation-mediated gene delivery of growth/differentiation factor 11 (Gdf11). (38/535)

The long-term goal of dental treatment is to preserve teeth and prolong their function. In dental caries an efficient method is to cap the exposed dental pulp and conserve the pulp tissue with reparative dentin. We examined whether growth/differentiation factor 11 (GDF11), a morphogen could enhance the healing potential of pulp tissue to induce differentiation of pulp stem cells into odontoblasts by electroporation-mediated gene delivery. Recombinant human GDF11 induced the expression of dentin sialoprotein (Dsp), a differentiation marker for odontoblasts, in mouse dental papilla mesenchyme in organ culture. The Gdf11 cDNA plasmid which was transferred into mesenchymal cells derived from mouse dental papilla by electroporation, induced the expression of Dsp. The in vivo transfer of Gdf11 by electroporation stimulated the reparative dentin formation during pulpal wound healing in canine teeth. These results provide the scientific basis and rationale for gene therapy for endodontic treatments in oral medicine and dentistry.  (+info)

E- and N-cadherin distribution in developing and functional human teeth under normal and pathological conditions. (39/535)

Cadherins are calcium-dependent cell adhesion molecules involved in the regulation of various biological processes such as cell recognition, intercellular communication, cell fate, cell polarity, boundary formation, and morphogenesis. Although previous studies have shown E-cadherin expression during rodent or human odontogenesis, there is no equivalent study available on N-cadherin expression in dental tissues. Here we examined and compared the expression patterns of E- and N-cadherins in both embryonic and adult (healthy, injured, carious) human teeth. Both proteins were expressed in the developing teeth during the cap and bell stages. E-cadherin expression in dental epithelium followed an apical-coronal gradient that was opposite to that observed for N-cadherin. E-cadherin was distributed in proliferating cells of the inner and outer enamel epithelia but not in differentiated cells such as ameloblasts, whereas N-cadherin expression was up-regulated in differentiated epithelial cells. By contrast to E-cadherin, N-cadherin was also expressed in mesenchymal cells that differentiate into odontoblasts and produce the hard tissue matrix of dentin. Although N-cadherin was not detected in permanent intact teeth, it was re-expressed during dentin repair processes in odontoblasts surrounding carious or traumatic sites. Similarly, N-cadherin re-expression was seen in vitro, in cultured primary pulp cells that differentiate into odontoblast-like cells. Taken together these results suggest that E- and N-cadherins may play a role during human tooth development and, moreover, indicate that N-cadherin is important for odontoblast function in normal development and under pathological conditions.  (+info)

Dental and skeletal stem cells: potential cellular therapeutics for craniofacial regeneration. (40/535)

The study of stem cells has received considerable attention since the discovery that adult stem cells have the capacity to form many different tissue types. Technical advances have helped identify potential stem cells, and their capacity for regenerating tissues is being studied in transplantation models. Further study of the isolation, nature, and differentiation potential of stem cells will likely have a positive impact on our understanding of human development and regenerative medicine. This review highlights the difference between embryonic and adult stem cells and discusses the potential use of these cells for cellular therapeutics for craniofacial regeneration.  (+info)