Gut microbiota regulates the ALK5/NOX1 axis by altering glutamine metabolism to inhibit ferroptosis of intrahepatic cholangiocarcinoma cells.

Intrahepatic cholangiocarcinoma (ICC) is a kind of hepatobiliary tumor that is increasing in incidence and mortality. The gut microbiota plays a role in the onset and progression of cancer, however, the specific mechanism by which the gut microbiota acts on ICC remains unclear. In this study, feces and plasma from healthy controls and ICC patients were collected for 16S rRNA sequencing or metabolomics analysis. Gut microbiota analysis showed that gut microbiota abundance and biodiversity were altered in ICC patients compared with controls. Plasma metabolism analysis showed that the metabolite glutamine content of the ICC patient was significantly higher than that of the controls. KEGG pathway analysis showed that glutamine plays a vital role in ICC. In addition, the use of antibiotics in ICC animals further confirmed that changes in gut microbiota affect changes in glutamine. Further experiments showed that supplementation with glutamine inhibited ferroptosis and downregulated ALK5 and NOX1 expression in HuCCT1 cells. ALK5 overexpression or NOX1 overexpression increased NOX1, p53, PTGS2, ACSL4, LPCAT3, ROS, MDA and Fe2+ and decreased FTH1, SLC7A11 and GSH. Knockdown of NOX1 suppressed FIN56-induced ferroptosis. In vivo, supplementation with glutamine promoted tumor growth. Overexpression of ALK5 repressed tumor growth and induced ferroptosis in nude mice, which could be reversed by the addition of glutamine. Our results suggested that the gut microbiota altered glutamine metabolism to inhibit ferroptosis in ICC by regulating the ALK5/NOX1 axis.

Manipulating Vertical Phase Separation Enables Pseudoplanar Heterojunction Organic Solar Cells Over 19% Efficiency via Ternary Polymerization.

Controlling vertical phase separation of the active layer to enable efficient exciton dissociation and charge carrier transport is crucial to boost power conversion efficiencies (PCEs) of pseudoplanar heterojunction (PPHJ) organic solar cells (OSCs). However, how to optimize the vertical phase separation of PPHJ OSCs via molecule design is rarely reported yet. Herein, ternary polymerization strategy is employed to develop a series of polymer donors, DL1-DL4, and regulate their solubility, molecular aggregation, molecular orientation, and miscibility, thus efficiently manipulating vertical phase separation in PPHJ OSCs. Among them, DL1 not only has enhanced solubility, inhibited molecular aggregation and partial edge-on orientation to facilitate acceptor molecules, Y6, to permeate into polymer layer and increase donor/acceptor interfaces, but also sustains high crystallinity and appropriate miscibility with Y6 to acquire ordered molecular packing, thus achieving optimized vertical phase separation to well juggle exciton dissociation and charge transport in PPHJ devices. Therefore, DL1/Y6 based PPHJ OSCs gain the best exciton dissociation probability, highest charge carrier mobilities and weakest charge recombination, and thus afford an impressive PCE of 19.10%, which is the record value for terpolymer donors. It demonstrates that ternary polymerization is an efficient method to optimize vertical phase separation in PPHJ OSCs for high PCEs.

Sequentially activating macrophages M1 and M2 phenotypes by lipopolysaccharide-containing Mg-Fe layered double hydroxides coating on the Ti substrate.

As cells of innate immunity, macrophages are a class of innate immune cells existing in almost all tissues and play a crucial role in bone repair. However, it remains a challenge to modulate the sequential activation of the deferent phenotypes in macrophage when designing the titanium (Ti) implants. In this study, the Mg-Fe layered double hydroxides (LDHs) was coated on Ti substrate through hydrothermal treatment. Further on lipopolysaccharide (LPS) was introduced onto the LDHs through adsorption and ions exchange. The adsorption efficiency of the coating on LPS reached 72.8% in 24 h due to the anion exchange and electrostatic interactions between the LPS and the LDH layers in deionized water. The LDHs-LPS coating released a large amount of LPS in the early stage, which induced macrophages into M1 phenotype via activating TLR-4 → MyD88 and TLR-4 → Ticam-1/2 signal pathways. Subsequently, the M1 macrophages were transformed into M2 phenotype by regulating the integrin α5ß1 of cells by the nanostructures, wetting angle and Mg2+ of the coating. The LDHs-LPS coating endows Ti with the ability of stage immunomodulation, indicating the positive osteoimmunomodulatory property.

Reducing Trap Density in Organic Solar Cells via Extending the Fused Ring Donor Unit of an A-D-A-Type Nonfullerene Acceptor for Over 17% Efficiency.

The high trap density (generally 1016 to 1018  cm-3 ) in thin films of organic semiconductors is the primary reason for the inferior charge-carrier mobility and large nonradiative recombination energy loss (ΔEnr ) in organic solar cells (OSCs), limiting improvement in power conversion efficiencies (PCEs). In this study, the trap density in OSCs is efficiently reduced via extending the donor core of nonfullerene acceptors (NFAs) from a heptacyclic unit to a nonacyclic unit. TTPIC-4F with a nonacyclic unit has stronger intramolecular and intermolecular interactions, affording higher crystallinity in thin films relative to its counterpart BTPIC-4F. Thus, the D18:TTPIC-4F-based device achieves a lower trap density of 4.02 × 1015  cm-3 , comparable to some typical high-performance inorganic/hybrid semiconductors, with higher mobility and inhibited charge-carrier recombination in devices. Therefore, the D18:TTPIC-4F-based OSC exhibits an impressive PCE of 17.1% with a low ΔEnr of 0.208 eV, which is the best known value for A-D-A-type NFAs. Therefore, extending the donor core of NFAs is an efficient method for suppressing trap states in OSCs for high PCEs.

LncRNA FIRRE promotes the proliferation and metastasis of hepatocellular carcinoma by regulating the expression of PXN through interacting with MBNL3.

Hepatocellular carcinoma (HCC) has been a long-time public health problem impacting people's heath and challenging healthcare professions because of its poor prognosis and high lethality. More and more evidence indicated the important role of long non-coding RNAs (lncRNAs) in carcinogenesis and cancer metabolism in a variety of cancer types. In this study, we found that FIRRE, a recently identified cancer-associated lncRNA located on chromosome X, is highly expressed in HCC cell lines and tissue samples, and its expression is positively correlated with poor HCC prognosis. In vitro and in vivo functional analyses showed that FIRRE could promote the proliferation, migration, and invasion of HCC. As for the potential mechanism, FIRRE specifically binds to the splicing factor MBNL3 to affect the expression of PXN to regulate the pathological characteristics of HCC cells. In summary, our study showed that the lncRNA FIRRE is a cancer promoting factor and may be a potential biomarker for the prognosis and drug target for the treatment of HCC.

Loss of ARID1A Promotes Hepatocellular Carcinoma Progression via Up-regulation of MYC Transcription.

BACKGROUND AND AIMS: AT-rich interactive domain-containing protein 1A (ARID1A) is frequently mutated or deficient in hepatocellular carcinoma (HCC). However, the role of ARID1A in HCC remains unclear. Therefore, the biological role of ARID1A in HCC was evaluated and a potential mechanism was investigated. METHODS: Arid1a was knocked out in the livers of mice using the CRISPR/Cas9 system delivered by hydrodynamic tail vein injection. The development of HCC was observed in different mouse models. The correlation of ARID1A and prognosis in patients with HCC was analyzed using cBioPortal. The effect of ARID1A on cell proliferation was assessed by MTT assay following the manipulation of candidate genes. RESULTS: ARID1A deficiency alone did not cause HCC in mice, but knockout of ARID1A accelerated liver tumorigenesis in response to diethylnitrosamine (DEN) or when a combination knockout of phosphatase and tensin homolog (Pten) plus tumor protein P53 (p53) was introduced. ARID1A mutations were associated with a poorer prognosis in HCC patients. The mRNA level of MYC was significantly higher in patients with an ARID1A mutation compared to those without a mutation. Ectopic expression of ARID1A inhibited HCC cell proliferation. ARID1A knockout increased HCC cell growth and resulted in disruptions to DNA damage repair and apoptosis following radiation stress. Furthermore, mechanistic studies revealed that ARID1A inhibited the proliferation of HCC cells via transcriptional down-regulation of MYC. CONCLUSIONS: These results describe ARID1A as a tumor suppressor in the liver. A deficiency in ARID1A predicts worse survival in HCC patients and promotes HCC progression via up-regulation of MYC transcription.

Association of PTEN expression with liver function and inflammatory changes in patients with liver cancer after chemotherapy.

This study investigated the effects of phosphatase and tensin homolog deleted on chromosome ten (PTEN) expression on liver function classification, serum tumor markers and liver function of patients with liver cancer. A total of 63 patients with primary liver cancer treated in Xiangya Hospital (Changsha, China) were retrospectively analyzed. The difference in the PTEN expression levels in normal liver cells and liver cancer cells was compared via immunohistochemistry. According to the expression level of PTEN in the patient's pathological report, patients were divided into PTEN-positive and PTEN-negative groups. The expression level of each tumor marker in serum of patients was observed, and the association of PTEN expression level with the serum tumor markers was analyzed. Moreover, the changes in liver function and inflammatory factors before and after chemotherapy were compared. Finally, the relationship between the PTEN expression level and Child-Pugh grading of the liver function was detected. Compared with that in normal liver cells, the positive expression rate of PTEN protein in liver cancer cells was significantly decreased (P<0.05). No significant difference was found in the expression levels of serum tumor markers, except α-fetoprotein (AFP) in liver cancer patients between PTEN-positive and PTEN-negative group, indicating that PTEN expression has no significant effects on serum tumor markers. The levels of albumin (ALB), alkaline phosphatase (ALP) and prothrombin activity (PTA) were decreased significantly after chemotherapy compared with those before chemotherapy (P<0.05). Besides, the levels of inflammatory factors were remarkably reduced after chemotherapy. PTEN expression was negatively associated with liver function grading, and the higher the PTEN expression, the lower the liver function grading was. The low expression of PTEN has a certain association with the occurrence and grading of liver cancer. PTEN gene has guiding significance in predicting the occurrence, development and prognosis of liver cancer.

Long noncoding RNA NNT-AS1 promotes hepatocellular carcinoma progression and metastasis through miR-363/CDK6 axis.

Long non-coding RNAs (lncRNAs) have been tested to act as important regulator in liver cancer genesis and progression. LncRNA Nicotinamide Nucleotide Transhydrogenase-antisense RNA1 (NNT-AS1) has been reported to participate in the tumorigenesis. However, the exact molecular mechanism of NNT-AS1 in hepatocellular carcinoma (HCC) is still unknown. In present study, our team identified the up-regulated expression of NNT-AS1 in HCC tissue and cell lines compared with adjacent noncancerous tissue and normal cells. Moreover, HCC patients with high NNT-AS1 levels had poor prognosis than that with low NNT-AS1 level (p=0.0089). In vitro, gain- and loss-of-function experiments revealed that enhanced NNT-AS1 expression promoted the proliferation ability and alleviated the cycle arrest and apoptosis, while NNT-AS1 knockdown suppressed the proliferation and induced G0/G1 phase arrest and apoptosis. In vivo, NNT-AS1 knockdown inhibited the HCC neoplastic tumor volume and weight. Bioinformatics analysis and luciferase reporter assay validated that miR-363 targeted NNT-AS1 and CDK6 3'-UTR. MiR-363 was down-regulated in HCC tissue and cells. NNT-AS1 competed with CDK6 for miR-363 binding and could increase CDK6 expression. In summary, our results suggest the oncogenic role of NNT-AS1 in HCC tumorigenesis through miR-363/CDK6 axis, providing a novel therapeutic target for human HCC.

Resveratrol enhances anticancer effects of paclitaxel in HepG2 human liver cancer cells.

BACKGROUND: The aim of this in vitro study was to measure the enhanced anticancer effects of Res (resveratrol) on PA (paclitaxel) in HepG2 human liver cancer cells. METHODS: The MTT (thiazolyl blue tetrazolium bromide, 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide), flow cytometry, qPCR (real-time quantitative polymerase chain reaction) and western blot assay were used for cells growth inhibitory effects, cells apoptosis (DNA content of sub-G1), mRNA and protein expressions, respectively. RESULTS: The 10 µg/mL of Res had no growth inhibitory effect on Nthy-ori 3-1 normal cells or HepG2 cancer cells meanwhile the 5 or 10 µg/mL of PA also had no growth inhibitory effect on Nthy-ori 3-1 normal cells. Where as PA-L (5 µg/mL) and PA-H (10 µg/mL) had the growth inhibitory effects in HepG2 cancer cells, and Res increase these growth inhibitory effects. By flow cytometry experiment, after Res (5 µg/mL) + PA-H (10 µg/mL) treatment, the HepG2 cells showed the most apoptosis in cells as compared to other treatments groups, and after additionally treated with Res, both the apoptosis cells of two concentrations PA were raised. As PA raised it also raised the mRNA and protein expressions of caspase-3, caspase-8, caspase-9, Bax (Bcl-2 assaciated X protein), p53, p21, IκB-α (inhibitor of NF-κB alpha), Fas (factor associated suicide), FasL (factor associated suicide ligand), TIMP-1 (tissue inhibitor of metalloproteinases 1), TIMP-2 (tissue inhibitor of metalloproteinases 2) and decrease Bcl-2 (B cell leukemia 2), Bcl-xL (B cell leukemia extra large), HIAP-1 (cIAP-1, cellular inhibitor of apoptosis 1), HIAP-2 (cIAP-2, cellular inhibitor of apoptosis 2), NF-κB (nuclear factor kappa B), COX-2 (cyclooxygenase 2), iNOS (inducible nitric oxide synthase), MMP-2 (metalloproteinase 2), MMP-9 (metalloproteinase 9), EGF (epidermal growth factor), EGFR (epidermal growth factor receptor), VEGF (vascular endothelial growth factor), Fit-1 (VEGFR-1, vascular endothelial growth factor receptor 1). Meanwhile, the 5 µg/mL of Res could enhance these mRNA expressions changes as compared to the control cells. CONCLUSION: From these results, we can conclude that Res could raise the anticancer effects of PA in HepG2 cells, Res could be used as a good sensitizing agent for PA.

Inhibition of ERK1/2 Signaling Impairs the Promoting Effects of TGF-ß1 on Hepatocellular Carcinoma Cell Invasion and Epithelial-Mesenchymal Transition.

Transforming growth factor-ß (TGF-ß) and ERK signaling have been implicated in various human cancers including hepatocellular carcinoma, but the underlying mechanism remains largely unclear. In this study, we aimed to explore the role of ERK1/2 in the regulation of TGF-ß's promoting and suppressive activities in HCC cells. Our data showed that treatment with TGF-ß1 enhanced invasion and epithelial-mesenchymal transition (EMT) in HCC HepG2 cells, accompanied with increased MMP9 production and activation of Smad2/3 and ERK1/2, but inhibited tumor cell proliferation. These effects were eliminated by treatment with SB431542, a TGF-ß inhibitor. Afterward, treatment with the MEK1/2 inhibitor U0126 reduced the TGF-ß1-induced invasion and vimentin and MMP9 secretion in HepG2 cells, without affecting the inhibitory effects of TGF-ß1 on HepG2 cell proliferation. Moreover, inhibition of Smad2/3 expression attenuated TGF-ß1-induced cell invasion, ERK1/2 phosphorylation, and MMP9 production in HepG2 cells. However, knockdown of Slug only reduced cell invasion but did not affect ERK1/2 activation and MMP9 secretion in HepG2 cells. These data indicate that TGF-ß1 activates ERK1/2 in HepG2 cells through the Smad2/3 pathway but not the Slug pathway. In summary, our study demonstrates that inhibition of ERK1/2 signaling attenuates the promoting effects of TGF-ß1 on the metastatic phenotypes of HCC cells without affecting its suppressive effects on HCC cell proliferation. Therefore, we suggest that ERK1/2 may be used as a molecular target for the treatment of TGF-ß-responsive HCC.

Autophagy prevention sensitizes AKTi-1/2-induced anti-hepatocellular carcinoma cell activity in vitro and in vivo.

Molecule-targeted therapy has become the research focus for hepatocellular carcinoma (HCC). Persistent PI3K-AKT activation is often detected in HCC, representing a valuable oncotarget for treatment. Here, we tested the anti-HCC activity by a potent AKT inhibitor: AKT inhibitor 1/2 (AKTi-1/2). In both established (HepG2 and Huh-7) and primary human HCC cells, treatment with AKTi-1/2 inhibited cell survival and proliferation, but induced cell apoptosis. AKTi-1/2 blocked AKT-mTOR activation, yet simultaneously provoked cytoprotective autophagy in HCC cells. The latter was evidenced by ATG-5 and Beclin-1 upregulation, p62 downregulation as well as LC3B-GFP puncta formation. Autophagy inhibition, via pharmacological inhibitors (3-methyladenine, ammonium chloride, and bafilomycin A1) or Beclin-1 siRNA knockdown, significantly potentiated AKTi-1/2-induced HepG2 cell death and apoptosis. In nude mice, AKTi-1/2 intraperitoneal injection inhibited HepG2 tumor growth. Significantly, its anti-tumor activity in vivo was further sensitized when combined with Beclin-1 shRNA knockdown in HepG2 tumors. Together, these results demonstrate that autophagy activation serves as a main resistance factor of AKTi-1/2 in HCC cells. Autophagy prevention therefore sensitizes AKTi-1/2-induced anti-HCC activity in vitro and in vivo.

Experimental study on inhibition of the growth of human adenoid cystic cancer cells by RNA interference targeting against survivingene.

OBJECTIVE: To observe the influence of RNA interference targeting against survivin gene on the biological behaviors of human adenoid cystic cancer (ACC) cells and propose the action mechanism. METHOD: Specific siRNA (small interfering RNA) was constructed and transfected into ACC-2 cells using liposomes. The expressions of survivin and Caspase-3 in the transfected ACC-2 cells were detected by Western Blot and RT-PCR. Cell apoptosis was detected by transmission electron microscopy, TUNEL method and flow cytometry; ultrastructural changes and cell cycles were observed. RESULTS: Recombinant siRNA interference plasmid specifically targeting against survivin gene was constructed successfully. Survivin protein expression in the transfected ACC-2 cells was downregulated significantly, while Caspase-3 protein and mRNA expressions were upregulated and cell proliferation was inhibited considerably. CONCLUSION: Recombinant siRNA interference plasmid inhibited survivin mRNA and protein expressions at high efficiency, thereby inhibiting the proliferation of ACC cells.

Cyclic tension promotes osteogenic differentiation in human periodontal ligament stem cells.

Orthodontic forces result in alveolar bone resorption and formation predominantly on the pressure and tension sides of the tooth roots, respectively. Human periodontal ligament stem cells (PDLSCs) have demonstrated the capacity to differentiate into osteoblasts, and they play important roles in maintaining homeostasis and regenerating periodontal tissues. However, little is known about how PDLSCs contribute to osteoblastogenesis during orthodontic tooth movement on the tension side. In this study, we applied a 12% cyclic tension force to PDLSCs cultured in osteoinductive medium. The osteogenic markers Runx2, ALP, and OCN were detected at the mRNA and protein levels at different time points using real-time PCR and western blot analyses. We discovered that the mRNA and protein levels of Runx2, ALP and OCN were significantly up-regulated after 6, 12 and 24 hours of mechanical loading on PDLSCs compared to levels in unstimulated PDLSCs (P < 0.05). This study demonstrates, for the first time, the effects of mechanical tensile strain on the osteogenic differentiation of PDLSCs, as examined with a Flexcell FX-4000T Tension Plus System. Our findings suggested that cyclic tension could promote the osteogenic differentiation of PDLSCs. Furthermore, the effects of orthodontic force on alveolar bone remodeling might be achieved by PDLSCs.

Successful liver resection in a giant hemangioma with intestinal obstruction after embolization.

Hepatic hemangiomas are the most common benign tumor of the liver. Most hepatic hemangiomas remain asymptomatic and require no treatment. Giant hepatic hemangiomas with established complications, diagnostic uncertainty and incapacitating symptoms, however, are generally considered an absolute indication for surgical resection. We present a case of a giant hemangioma with intestinal obstruction following transcatheter arterial embolization, by which the volume of the hemangioma was significantly reduced, and it was completely resected by a left hepatectomy. A 21-year-old Asian man visited our hospital for left upper quadrant pain. Examinations at the first visit revealed a left liver hemangioma occupying the abdominal cavity, with a maximum diameter of 31.5 cm. Embolization of the left hepatic artery was performed and confirmed a decrease in its size. However, the patient was readmitted to our hospital one month after embolization for intestinal obstruction. A left hepatectomy was completed through a herringbone incision, and safely removed a giant hemangioma of 26.5 cm × 19.5 cm × 12.0 cm in size and 3690 g in weight. Pre-operative arterial embolization is effective for reducing tumor size, but a close follow-up to decide the time for hepatectomy is important.

Patterns of abdominal injury in 37 387 disaster patients from the Wenchuan earthquake.

OBJECTIVES: Due to lack of sufficient data it is difficult to understand fully the pattern of abdominal injury after an earthquake. This study aimed to evaluate the pattern of abdominal injury by analysing the data of trauma patients with abdominal injury incurred during the 2008 Wenchuan earthquake. METHODS: We retrospectively reviewed the medical records of 37387 inpatients. Among them, 883 (2.36%) cases of abdominal injury were deemed eligible and enrolled for analysis. The data analysed included demographics, category of abdominal injury, associated injury type, cause of injury, treatment and clinical outcome, as well as risk factors for death. RESULTS: Abdominal injury was often accompanied with multiple injuries. Injury of the abdominal wall was the most frequent type of earthquake-related abdominal injury (32%). The spleen was the most commonly injured abdominal organ (18%). Of the 883 patients evaluated, 221 cases received operations and 41 cases died. The highest death rate was found in patients with haemorrhagic shock (28/41, 68.3%) caused by intra-abdominal bleeding. CONCLUSIONS: Abdominal injuries are relatively uncommon in earthquake disasters and often present with associated injuries. A timely and complete diagnosis of both abdominal as well as associated injuries is of primary importance in the treatment of patients with abdominal injuries. Knowledge of different types of abdominal injury, and their relative proportions, prevalence of associated injuries, risk factors and final clinical outcomes observed in this study may be of valuable reference in dealing with major earthquake events in the future.

Ectopically expressed IBP promotes cell proliferation in oral squamous cell carcinoma.

IFN regulatory factor 4 binding protein (IBP) has been shown to play an important role in the progression of malignant tumors such as breast cancer cells, but its function in oral squamous cell carcinoma (OSCC) remains unclear. We found that IBP ectopically expressed in some OSCC specimens but not in normal oral mucosa epithelium tissues. IBP expression was significantly correlated with tumor size, differentiation, clinical stage, and distant metastasis. Furthermore, IBP markedly promoted OSCC cell proliferation, shortened the G1 interval in the cell cycle, and increased cyclin D1 expression. These findings suggest that IBP may be a potential therapeutic target for OSCC.

Screening ultrasonography of 2,204 patients with blunt abdominal trauma in the Wenchuan earthquake.

BACKGROUND: Abdominal injuries constitute a small proportion of all earthquake-related traumas; however, it often resulted in fatal hemorrhage. Ultrasonography has been described as an effective triage tool in the evaluation of blunt abdominal trauma. We aimed to present an overview of the diagnostic accuracy of screening ultrasonography for patients with blunt abdominal trauma admitted to various hospitals during the Wenchuan earthquake in China. METHODS: We retrospectively analyzed the patients with blunt abdominal trauma who underwent ultrasonography after admission to various hospitals. Ultrasonography findings were considered positive if evidence of free fluid or a parenchymal injury was identified. Ultrasonography findings were compared with the findings of computed tomography, diagnostic peritoneal lavage, repeated ultrasonography, cystography, operation, and/or the clinical course. RESULTS: Findings from 2,204 ultrasonographic examinations were evaluated. Findings of 199 ultrasonographic examinations (9.0%) were considered positive. Of the patients, 12 (0.5%) had a false-negative ultrasonographic findings; of this group, 3 (25%) required exploratory laparotomy. Ultrasonography had a sensitivity of 91.9%, specificity of 96.9%, and an accuracy of 96.6% for detection of abdominal injuries. Positive predictive value was 68.3%, and negative predictive value was 99.4%. CONCLUSION: Screening ultrasonography is highly reliable in the setting of blunt abdominal trauma after earthquake. It should be used as an initial diagnostic modality in the evaluation of most blunt abdominal trauma. LEVEL OF EVIDENCE: Diagnostic study, level III.

[Isolation and identification of human periodontal ligament stem cells in vitro].

OBJECTIVE: To isolate and identify human periodontal ligament stem cells (PDLSC) by improved methods and assess the characteristics of PDLSC ex vivo. METHODS: The periodontal ligament cells were obtained from the healthy impacted third molars and teeth extracted for orthodontic purposes and used to isolate PDLSC by limiting dilution assay. PDLSC were cultured and expanded in alpha-MEM supplemented with 10% FBS. Colony-forming assay, immunohistochemistry, flow cytometry, osteogenic and adipogenic induction were used to identify PDLSC. RESULTS: The obtained cells had high colony-forming efficiency and were positive staining for vimentin and negative for pancytokeratin. Flow cytometry revealed that the isolated cells were positive for STRO-1 and CD146 antibodies and most were in the G0/G1 phase of cell cycle. Under specific conditions, they could differentiate to the osteoblast and adipocyte lineages in vitro. CONCLUSION: Limiting dilution assay is an effective method to isolate PDLSC and the single-cell-derived colonies demonstrate the properties of stem cells in vitro.

[Influence of bicortical anchorage on the natural frequencies of dental implant].

OBJECTIVE: To investigate the influences of bicortical anchorage on values of natural frequencies of dental implants utilizing the 3-dimensional finite element analysis. METHODS: Using the commercial code of Solidworks, 3-D models of a screw-shaped dental implant and a mandibular bone segment were generated. After the 3-D implant-bone complex was meshed by ABAQUS software, effects of bicortical anchorage on the buccolingual and axial first-order natural frequencies of the implant were computed. RESULTS: Bicortical anchorage increased both the buccolingual and axial natural frequencies remarkably. As the bicortical anchorage got deeper, the frequencies correspondingly got higher. CONCLUSION: Bicortical anchorage can increase the buccolingual and axial primary stability of dental implants.