Off-target activity of the 8 kb Dmp1-Cre results in the deletion of Tsc1 gene in mouse intestinal mesenchyme.

The Dmp1-Cre mouse, expressing Cre from an 8-kb DNA fragment of the mouse Dmp1 gene, is a common tool to study gene functions in osteocytes. Here we report that the deletion of Tsc1 (TSC complex subunit 1) by 8 kb Dmp1-Cre causes rectal prolapse in mice. Histological examination shows the presence of colon polyps in Tsc1-deficient mice in association with significantly larger colon and narrower lumen, which recapitulates the common polyps pathology in Tuberous Sclerosis, an autosomal dominant disorder caused by mutations in either TSC1 or TSC2. The intestine in Tsc1-deficient mice is also enlarged with the presence of taller villi. Using the Ai14 reporter mice that express a red fluorescence protein upon Cre recombination, we show that 8 kb Dmp1-Cre activity is evident in portion of the mesenchyme of the colon and small intestine. Lastly, our data show that Tsc1 deletion by Dmp1-Cre leads to an increased proliferation in the mesenchyme of colon, which at least partly contributes to the polyps pathology seen in this mouse model and is likely a contributing factor of the polyps in Tuberous Sclerosis.

Expression of Cre recombinase in chondrocytes causes abnormal craniofacial and skeletal development.

The cranial base synchondroses are growth centers that drive cranial and upper facial growth. The intersphenoid synchondrosis (ISS) and the spheno-occipital synchondrosis (SOS) are two major synchondroses located in the middle of the cranial base and are maintained at early developmental stages to sustain cranial base elongation. In this study, we report unexpected premature ossification of ISS and SOS when Cre recombinase is activated in a chondrocyte-specific manner. We used a Cre transgenic line expressing Aggrecan enhancer-driven, Tetracycline-inducible Cre (ATC), of which expression is controlled by a Col2a1 promoter. Neonatal doxycycline injection or doxycycline diet fed to breeders was used to activate Cre recombinase. The premature ossification of ISS and/or SOS led to a reduction in cranial base length and subsequently a dome-shaped skull. Furthermore, the mice carrying either heterozygous or homozygous conditional deletion of Tsc1 or Fip200 using ATC mice developed similar craniofacial abnormalities, indicating that Cre activity itself but not conditional deletion of Tsc1 or Fip200 gene, is the major contributor of this phenotype. In contrast, the Col2a1-Cre mice carrying Cre expression in both perichondrium and chondrocytes and the mice carrying the conditional deletion of Tsc1 or Fip200 using Col2a1-Cre did not manifest the same skull abnormalities. In addition to the defective craniofacial bone development, our data also showed that the Cre activation in chondrocytes significantly compromised bone acquisition in femur. Our data calls for the consideration of the potential in vivo adverse effects caused by Cre expression in chondrocytes and reinforcement of the importance of including Cre-containing controls to facilitate accurate phenotype interpretation in transgenic research.

Excision margin of T3 basal cell carcinoma in maxillofacial area: A retrospective cohort study of Asians.

OBJECTIVES: Basal cell carcinoma is the most common skin cancer worldwide. Surgical excision is considered as the mainstay of treatment, while the evidence of excision margin in advanced stage is lacking, especially in maxillofacial area. MATERIALS AND METHODS: We conducted a 2-center retrospective cohort study. Disease-free survival rate was estimated for 116 Asian patients with T3 basal cell carcinoma in maxillofacial area who received stand surgical excision with margin of 3-5 mm (Group A), 6-9 mm (Group B), and 10-15 mm (Group C). RESULTS: For the entire cohort, five-year disease-free survival rates of Groups A, B, and C were 82.1%, 93.5%, and 92.4%, respectively. When compared with Group B, Group A was correlated with lower disease-free survival rate (HR 5.48, p = .04), and Group C was not associated with different disease-free survival rate (HR 0.85, p = .62). Perineural invasion (p = .006) and pathologic subtypes of infiltrative basal cell carcinoma (p = .01) were independent prognosticator for disease-free survival rate. CONCLUSIONS: This multicenter cohort study validated that T3 basal cell carcinoma Asian patients of maxillofacial area treated with excision margin of 6-9 mm had a substantial benefit of disease-free survival rate and skin conservation.

In Vitro Induction of Human Dental Pulp Stem Cells to Lymphatic Endothelial Cells.

Lymphedema is a progressive and irreversible disease due to the lymphatic system disorder. Conservative and surgical therapies are either ineffective or impractical. Currently, mesenchymal stem cells (MSCs)-based therapies seem to be the most promising treatment for lymphedema. The MSCs promote lymphangiogenesis through the paracrine approach or by directly differentiating into lymphatic endothelial cells (LECs) under the induction of growth factors. Human dental pulp stem cells (hDPSCs) have been suggested to play important roles in tissue regeneration, making it an attractive candidate for the lymphedema treatment. In this study, to evaluate the potential role of hDPSCs in the clinical application for lymphedema treatment, we induced the hDPSCs with vascular endothelial growth factor-C (VEGF-C) and investigated the lymphangiogenic differentiation potential of hDPSCs in vitro. We found that under the VEGF-C induction, hDPSCs demonstrated upregulated LECs specific markers, promoted cell proliferation and migration, and increased tube formation, all of which contributed to their differentiation into LECs in vitro.

Cardiovascular Response of Aged Outpatients With Systemic Diseases During Tooth Extraction: A Single-Center Retrospective Observational Study.

Background: Aged people are maintaining many natural teeth due to improved oral health. However, compromised general health and poor oral hygiene habits at earlier ages resulted in poor status of preserved teeth. Therefore, tooth extraction is required in many aged people. More knowledge is needed because there are many risk factors during the surgery in frail aged adults. The aim of this study was to evaluate the cardiovascular response of such a population during tooth extraction and analyze risk factors to provide clinical guidance. Methods: A retrospective study was performed on aged patients with systemic diseases who underwent tooth extraction. Data regarding demographic profiles and cardiovascular parameters of heart rate and blood pressure were collected preoperative, when local anesthesia was administered, at the beginning of tooth extraction, 5 min after tooth extraction, and postoperative. The effects of risk factors, including age, sex, and systemic diseases on these parameters were analyzed with a multilevel model. Results: Heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) of aged patients increased significantly when performing local anesthesia and tooth extraction. During the operation, the older patients (ß = 2.011, P = 0.005) and the diabetics (ß = 3.902, P < 0.0001) were associated with higher SBP, while those with more tooth extractions exhibited higher HR (ß = 0.893, P = 0.007). Women patients showed both significantly elevated HR (ß = 1.687, P < 0.0001) and SBP (ß = 2.268, P < 0.0001). However, for coronary artery disease patients, HR (ß = -2.747, P < 0.0001) and blood pressure [SBP (ß = -4.094, P < 0.0001) and DBP (ß = -0.87, P = 0.016)] were markedly lower than those of patients without a diagnosis of coronary artery disease. Conclusion: Cardiovascular response of aged outpatients with systemic diseases during tooth extraction is quite significant. Age, sex, systemic diseases, and the number of tooth extraction could be risk factors closely associated with cardiovascular response. The findings might provide safety guidance for dentists on tooth extraction in this population.

Chondrocyte Tsc1 controls cranial base bone development by restraining the premature differentiation of synchondroses.

Cranial base bones are formed through endochondral ossification. Synchondroses are growth plates located between cranial base bones that facilitate anterior-posterior growth of the skull. Coordinated proliferation and differentiation of chondrocytes in cranial base synchondroses is essential for cranial base bone growth. Herein, we report that constitutive activation of the mechanistic target of rapamycin complex 1 (mTORC1) signaling via Tsc1 (Tuberous sclerosis 1) deletion in chondrocytes causes abnormal skull development with decreased size and rounded shape. In contrast to decreased anterior-posterior growth of the cranial base, mutant mice also exhibited significant expansion of cranial base synchondroses including the intersphenoid synchondrosis (ISS) and the spheno-occipital synchondrosis (SOS). Cranial base synchondrosis expansion in TSC1-deficient mice was accounted for by an expansion of the resting zone due to increased cell number and size without alteration in cell proliferation. Furthermore, our data showed that mTORC1 activity is inhibited in the resting and proliferating zone chondrocytes of wild type mice, and Tsc1 deletion activated mTORC1 signaling of the chondrocytes in the resting zone area. Consequently, the chondrocytes in the resting zone of TSC1-deficient mice acquired characteristics generally attributed to pre-hypertrophic chondrocytes including high mTORC1 activity, increased cell size, and increased expression level of PTH1R (Parathyroid hormone 1 receptor) and IHH (Indian hedgehog). Lastly, treatment with rapamycin, an inhibitor of mTORC1, rescued the abnormality in synchondroses. Our results established an important role for TSC1-mTORC1 signaling in regulating cranial base bone development and showed that chondrocytes in the resting zone of synchondroses are maintained in an mTORC1-inhibitory environment.

FAK Promotes Early Osteoprogenitor Cell Proliferation by Enhancing mTORC1 Signaling.

Focal adhesion kinase (FAK) has important functions in bone homeostasis but its role in early osteoprogenitor cells is unknown. We show herein that mice lacking FAK in Dermo1-expressing cells exhibited low bone mass and decreased osteoblast number. Mechanistically, FAK-deficient early osteoprogenitor cells had decreased proliferation and significantly reduced mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling, a central regulator of cell growth and proliferation. Furthermore, our data showed that the pharmacological inhibition of FAK kinase-dependent function alone was sufficient to decrease the proliferation and compromise the mineralization of early osteoprogenitor cells. In contrast to the Fak deletion in early osteoprogenitor cells, FAK loss in Col3.6 Cre-targeted osteoblasts did not cause bone loss, and Fak deletion in osteoblasts did not affect proliferation, differentiation, and mTORC1 signaling but increased the level of active proline-rich tyrosine kinase 2 (PYK2), which belongs to the same non-receptor tyrosine kinase family as FAK. Importantly, mTORC1 signaling in bone marrow stromal cells (BMSCs) was reduced if FAK kinase was inhibited at the early osteogenic differentiation stage. In contrast, mTORC1 signaling in BMSCs was not affected if FAK kinase was inhibited at a later osteogenic differentiation stage, in which, however, the concomitant inhibition of both FAK kinase and PYK2 kinase reduced mTORC1 signaling. In summary, our data suggest that FAK promotes early osteoprogenitor cell proliferation by enhancing mTORC1 signaling via its kinase-dependent function and the loss of FAK in osteoblasts can be compensated by the upregulated active PYK2. © 2020 American Society for Bone and Mineral Research.

Corrigendum to "Clinical analysis of medication related osteonecrosis of the jaws: A growing severe complication in China" [J Dent Sci 13 (3) (September 2018) 190-197].

[This corrects the article DOI: 10.1016/j.jds.2017.12.003.].

Clinical analysis of medication related osteonecrosis of the jaws: A growing severe complication in China.

BACKGROUND/PURPOSE: Medication-related osteonecrosis of the jaws (MRONJ) is an unusual but quite serious complication. However, its mechanism remains unclear, and its treatment protocol is still controversial. MATERIALS AND METHODS: Our study involved 201 osteonecrosis of the jaw (ONJ) patients from September 2006 to March 2017. We analyzed risk factors, clinical characteristics, treatment, etc., by comparing MRONJ with other ONJs. RESULTS: Among 201 patients, MRONJ accounted for 14.71% and it presented a consistent increase tendency. In comparison with other ONJs, we considered advanced age, maxilla lesion, diabetes mellitus, tooth extraction, especially multi-teeth extraction as risk factors (P < 0.0125). Our study demonstrated that maxillary lesion was associated with an advanced stage and it was inclined to worse prognoses. We also found MRONJ had little correlation to Actinomyces infection. Surgical treatment could improve patients' condition successfully (P > 0.05). 81.3% patients with advanced stage showed complete or partial healing lesions after surgery. CONCLUSION: Advanced age, maxilla lesion, diabetes mellitus, tooth extraction seem to be important triggering factors for MRONJ. Clinicians and surgeons should pay attention to maxillary lesions as it is related to severe symptoms and unfavorable prognosis. Once diagnosed as MRONJ, surgery is an effective treatment for patients with advanced stage.

Cell-based therapy for therapeutic lymphangiogenesis.

Lymphedema is a medically irreversible condition for which currently conservative and surgical therapies are either ineffective or impractical. The potential use of progenitor and stem cell-based therapies has offered a paradigm that may provide alternative treatment options for lymphatic disorders. Moreover, basic research, preclinical studies, as well as clinical trials have evaluated the therapeutic potential of various cell therapies in the field of lymphatic regeneration medicine. Among the available cell approaches, mesenchymal stem cells (MSCs) seem to be the most promising candidate mainly due to their abundant sources and easy availability as well as evitable ethical and immunological issues confronted with embryonic stem cells and induced pluripotent stem cells. In this context, the purpose of this review is to summarize various cell-based therapies for lymphedema, along with strengths and weaknesses of these therapies in the clinical application for lymphedema treatment. Particularly, we will highlight the use of MSCs for lymphatic regeneration medicine. In addition, the future perspectives of MSCs in the field of lymphatic regeneration will be discussed.

[Postoperative infection bacteria and drug resistance in patients with oral and maxillofacial tumors].

PURPOSE: To evaluate postoperative infection patterns of patients suffering from oral and maxillofacial neoplasms. The risk factors giving rise to postoperative infections were analyzed. Infection bacteria and antibiotic resistance were investigated. METHODS: Fifty-three cases suffering from postoperative infection were selected during 2007.12-2012.12 at the Department of Oral & Maxillofacial Surgery, West China College of Stomatology. The relationship between infections and factors including patients' sex, age, type of tumor, operation time and methods were evaluated with Excel and SPSS 21.0 software package, putting emphasis on infection bacteria and drug-resistance. RESULTS: Postoperative infection mainly occurred in patients with oral malignant tumors. Operation types and time had important influence on postoperative infection. The infection bacteria included gram-positive (59.5%) and gram-negative ones (40.5%). Streptococcus pyogenes accounted for the majority of G- bacteria, which was very sensitive to ß-lactam antibiotics. Pseudomonas aeruginosa were multi-drug resistant G- bacteria, which brought difficulties to the treatment of the infection. CONCLUSIONS: Integrant bacterial culture and drug sensitivity test should be performed to choose appropriate antibiotics, and monitor multi-drug resistant bacteria, so as to improve the control rates of postoperative infection.