Human Peripheral Nerve-Derived Pluripotent Cells Can Be Stimulated by In Vitro Bone Morphogenetic Protein-2.

We have recently identified a population of cells within the peripheral nerves of adult rodent animals (mice and rats) that can respond to Bone Morphogenetic Protein-2 (BMP-2) exposure or physical injury to rapidly proliferate. More importantly, these cells exhibited embryonic differentiation potentials that could be induced into osteoblastic and endothelial cells in vitro. The current study examined human nerve specimens to compare and characterize the cells after BMP-2 stimulation. Fresh pieces of human nerve tissue were minced and treated with either BMP-2 (750 ng/mL) or a PBS vehicle for 12 h at 37 °C, before being digested in 0.2% collagenase and 0.05% trypsin-EDTA. Isolated cells were cultured in a restrictive stem cell medium. Significantly more cells were obtained from the nerve pieces with the BMP-2 treatment in comparison with the PBS vehicle controls. Cell colonies started to form at Day 3. Expressions of the four transcription factors, namely, Klf4, c-Myc, Sox2, and Oct4, were confirmed at both the transcriptional and translational levels. The cells can be maintained in the stem cell culture medium for at least 6 weeks without changing their morphology. When the cells were transferred to a fibroblast growth medium, dispersed spindle-shaped motile cells were noted and became fibroblast activated protein-α (FAP) positive with immunocytochemistry staining. The data suggest that human peripheral nerve tissue also contains a population of cells that can respond to BMP-2 and express Klf4, Sox2, cMyc, and Oct4-the four transcription factors driving cell pluripotency. These cells are able to differentiate into FAP-positive fibroblasts. In summary, in human peripheral nerves also reside a population of quiescent cells with pluripotency potential that may be the same cells as rodent nerve-derived adult stem (NEDAPS) cells. It is proposed that these cells are possibly at the core of a previously unknown natural mechanism for healing an injury.

[Temporal and spacial expression of LIM mineralization protein 1 during rat pulp injury and reparation].

PURPOSE: To investigate the expression and localization of LIM mineralization protein 1(LMP-1) during rat pulp injury and reparation. METHODS: Dental pulp injury models were established in maxillary first molars on one side of 12 Wistar rats, the isonym healthy teeth on the opposite side were used as the controls. Immunohistochemistry technique was used to observe the expression of LMP-1 at 1, 3 and 7 day after pulp injury. The results of staining were analyzed by Image-Pro Plus 6.0 and SPSS 17.0 software package. RESULTS: LMP-1 was not detected in normal rat dental pulp. Positive staining of LMP-1 was found in odontoblasts and some dental pulp cells at 1 day after pulp injury. The expression of LMP-1 was converged at cell proliferation zone under the injury site at 3 and 7 day after injury. CONCLUSIONS: LMP-1 might play a role in the dental pulp cell proliferation and differentiation and reparative dentin formation during pulp injury and reparation.

[A comparative study of split-root and medial resistance removal in extraction of medially impacted tooth].

PURPOSE: To compare the operating time, root fracture and postoperative complications between split-root extraction and medial resistance removal in extraction of mandibular small-angle impacted third molars, to evaluate the advantages of split-root extraction in medially impacted tooth extraction. METHODS: Forty male patients with bilaterally mandibular medial small-angle impacted third molars, having multiple roots in panoramic films, were selected. The impacted teeth on one side were extracted by using split-root method, while the similar impacted teeth on the other side were extracted by using medial resistance removal method. The operating time, root fracture, postoperative pain, facial edema, and mouth opening were recorded. SPSS11.5 software package was used and paired t test was performed to analyze the data. RESULTS: There were significant differences in operating time and root fracture between the two methods (P<0.05). In the split-root group, the operating time was shorter and root fracture were less. After 24 hours, facial edema, limited mouth opening, and pain of the split-root group was less severe than that of the medial resistance removal group, differences were significant(P<0.05). After 72 hours, limited mouth opening of the split-root group was milder than that of the resistance removal group, the difference was significant (P<0.05). After 120 hours, there was no significant difference of any complications between the two groups. CONCLUSIONS: In extraction of mandibular medial small-angle impacted third molars with multiple roots, the operating time of split-root extraction is shorter. The root fracture possibility of split-root extraction is smaller, and postoperative complications are less common.