CAD/CAM and conventional reconstruction of the mandibular condyle by fibula free flap: a clinical and radiological evaluation.

The aim of this study was to analyse the radiological and clinical outcomes of condylar reconstruction by fibula free flap (FFF), comparing conventional freehand and CAD/CAM techniques. Fifteen patients (nine CAD/CAM, six freehand) who underwent condylar reconstruction with a FFF were reviewed retrospectively regarding pre- and postoperative computed tomography/cone beam computed tomography scans and clinical function. After surgery, all patients were free of temporomandibular joint pain. Mean postoperative mouth opening was 30.80 mm, with no significant difference between the freehand and CAD/CAM groups. In all patients, laterotrusion was decreased to the contralateral side (P = 0.002), with no difference between freehand and CAD/CAM, while the axis of mouth opening deviated to the side of surgery (P < 0.001). All patients showed significant radiological deviation of the fibular neocondyle in the laterocaudal direction (lateral: P = 0.015; caudal: P = 0.001), independent of the technique. In conclusion, reconstruction of the mandibular condyle by FFF provided favourable functional results in terms of mouth opening, reduction of pain, and mandibular excursions. Radiological deviation of the neocondyle and deviation of laterotrusion and mouth opening did not impair clinical function. CAD/CAM planning facilitated surgery, decreased the surgery time, and improved the fit of the neocondyle in the fossa.

Alternatives to free flap surgery for maxillofacial reconstruction: focus on the submental island flap and the pectoralis major myocutaneous flap.

BACKGROUND: Microvascular tissue transfer (MTT) has been established as the gold standard in oral- and maxillofacial reconstruction. However, free flap surgery may be critical in multimorbid elderly patients and after surgery or radiotherapy, which aggravate microsurgery. This study evaluates indications and outcome of the submental island flap (SMIF) and the pectoralis major myocutaneous flap (PMMF) as alternatives to the free radial forearm flap (RFF). METHODS: This retrospective study included 134 patients who had undergone resection and reconstruction with SMIF, PMMF, or RFF at our department between 2005 and 2020. The level of comorbidity was measured with the Age-adjusted Charlson comorbidity index (ACCI). Primary outcome variables were flap success, complications, wound dehiscence, surgery duration, as well as time at the ICU and the ward (hospitalization). Chi-square tests, t-tests, and ANOVA were performed for statistics. RESULTS: 24 SMIFs, 52 RFFs, and 58 PMMFs were included in this study. The flap types did not significantly differ in terms of flap success, complications, and healing disorders. The SMIF presented a success rate of 95.8% and was significantly more often used in elderly patients (mean age = 70.2 years; p < 0.001) with increased comorbidities than the PMMF (p < 0.01) and RFF (p < 0.001). SMIF reconstruction reduced surgery duration (p < 0.001) and time at the ICU (p = 0.009) and the ward (p < 0.001) more than PMMF and RFF reconstructions. PMMF reconstruction was successful in 91.4% of patients and was more frequently used after head and neck surgery (p < 0.001) and radiotherapy (p < 0.001) than SMIF and RFF reconstructions. Patients undergoing PMMF reconstruction more frequently required segmental jaw resection and had presented with advanced tumor stages (both p < 0.001). Nicotine and alcohol abuse was more frequent in the RFF and PMMF groups (both p < 0.001) than in the SMIF group. CONCLUSIONS: The pedicled SMIF represents a valuable reconstructive option for elderly patients with increased comorbidity because of the shorter duration of surgery and hospitalization. On the other hand, the PMMF serves as a solid backup solution after head and neck surgery or radiotherapy. The rates of flap success, complications, and healing disorders of both pedicled flaps are comparable to those of free flap reconstruction.

Magnetic resonance angiography for free fibula harvest: anatomy and perforator mapping.

The purpose of this study was to outline lower leg vessel anatomy and to investigate reliability and limitations of magnetic resonance angiography (MRA) in patients proposed for microvascular fibula transplantation (free fibula flap (FFF)). We retrospectively investigated MRAs of 99 patients considered for FFF. Frontal MRA planes and maximal intensity projections (MIPs) were evaluated for fibula lengths, anatomical branching pattern, arterial stenoses and fibular perforator positions in both legs (n=198). Normal branching patterns were observed in 168 (85.3%) legs. Twenty-nine (14.7%) legs presented abnormal branching patterns. Once (0.5%) the anterior, 19 times (9.6%) the posterior tibial artery were absent or hypoplastic. Nine (4.6%) lower legs presented an arteria peronea magna. Average length of the tibiofibular trunk (TFT) was 3.3±0.15cm. A total of 492 perforators were found with an average of 2.5 (±0.82±0.99) perforators per leg. A mapping of perforator run-offs was illustrated true to scale. Lower limb stenoses were distributed in the anterior tibial artery (14.1%), in the posterior tibial artery (11.1%) and in the fibular artery (8.1%). Smoking (P=0.828), diabetes (P=0.727) and peripheral arterial occlusive disease (P=0.172) did not correlate with presence of stenoses. Preoperative lower limb angiography avoids postoperative complications. MRA reliably and non-invasively identifies anatomical variants and arterial stenoses without radiation. Illustration of perforator run-offs enhances incision planning for fibula harvest.

Differential localization of PD-L1 and Akt-1 involvement in radioresistant and radiosensitive cell lines of head and neck squamous cell carcinoma.

Immunotherapy by blockade of the PD-1/PD-L1 checkpoint demonstrated amazing tumor response in advanced cancer patients including head and neck squamous cell carcinoma (HNSCC). However, the majority of HNSCC patients still show little improvement or even hyperprogression. Irradiation is currently investigated as synergistic treatment modality to immunotherapy as it increases the number of T-cells thereby enhancing efficacy of immunotherapy. Apart from this immunogenic context a growing amount of data indicates that PD-L1 also plays an intrinsic role in cancer cells by regulating different cellular functions like cell proliferation or migration. Here, we demonstrate opposing membrane localization of PD-L1 in vital and apoptotic cell populations of radioresistant (RR) and radiosensitive (RS) HNSCC cell lines up to 72 h after irradiation using flow cytometry. Moreover, strong PD-L1 expression was found in nuclear and cytoplasmic cell fractions of RR. After irradiation PD-L1 decreased in nuclear fractions and increased in cytoplasmic fractions of RR cells. In contrast, RS cell lines did not express PD-L1, neither in the nucleus nor in cytoplasmic fractions. Additionally, overexpression of PD-L1 in RS cells led to a proportional increase of vital PD-L1 positive cells after irradiation. Moreover, co-immunoprecipitation experiments revealed an interaction between Akt-1 and PD-L1, mostly in irradiated RR cells compared to RS cells suggesting a differential influence of PD-L1 on cell signaling. In summary, our data imply the need for different therapeutic strategies dependent on the molecular context in which PD-L1 is embedded.

Health-related quality of life: a retrospective study on local vs. microvascular reconstruction in patients with oral cancer.

BACKGROUND: New medicinal and surgical oncological treatment strategies not only improve overall survival rates but continually increase the importance of Health-Related Quality of Life (HRQOL). The purpose of this retrospective cross-sectional study was to analyze HRQOL of patients with oral squamous cell carcinoma after ablative surgery and to evaluate predictive factors for HRQOL outcome. METHODS: The study included 88 patients with histologically confirmed oral squamous cell carcinoma of whom 42 had undergone local reconstruction (LR) and 46 microvascular reconstruction (MVR). During follow-up, all patients completed the University of Washington Quality of Life Questionnaire (UW-QOL) containing 12 targeted questions about the head and neck. Descriptive analyses were made for the tumor site, the T-stage, and adjuvant therapies. HRQOL was compared between the LR and the MVR group with parametric tests. Further analyses were impact of the tumor site, the T-status, and the time from surgery to survey on HRQOL. Statistics also included multivariate correlations and different interaction effects. RESULTS: HRQOL in the LR group was 'very good' with 84.3 ± 13.7 and 'good' in the MVR group with 73.3 ± 16.5 points. The physical domains swallowing (p = 0.00), chewing (p = 0.00), speech (p = 0.01), taste (p = 0.01), and pain (p = 0.04) were significantly worse in the MVR group. An increase in the T-status had a significant negative effect on swallowing (p = 0.01), chewing (p = 0.01), speech (p = 0.03), recreation (p = 0.05), and shoulder (p = 0.01) in both groups. Regarding the tumor site and subsequent loss of HRQOL, patients with squamous cell carcinoma on the floor of the mouth had significantly worse results in the categories pain (p = 0.002), speech (p = 0.002), swallowing (p = 0.03), activity (p = 0.02), and recreation (p = 0.01) than patients with tumors in the buccal mucosa. Speech (p = 0.03) and pain (p = 0.01) had improved 1 year after surgery. CONCLUSION: Patients with flap reconstruction because of oral squamous cell carcinoma showed very good overall HRQOL. Outcomes for microvascular reconstruction were good, even in the case of larger defects. The T-status is a predictor for HRQOL. Swallowing, chewing, speaking, taste, and pain were the most important issues in our cohort. Implementing HRQOL questionnaires for the assessment of quality of life could further increase the treatment quality of patients with oral cancer.

Correction to: Induced surface proteins of Staphylococcus epidermidis adhering to titanium implant substrata.

There is a mistake in the original published version of this article. The word 'Streptococcus' in the article title should have been 'Staphylococcus'.

Induced surface proteins of Staphylococcus [corrected] epidermidis adhering to titanium implant substrata.

OBJECTIVE: Staphylococcus epidermidis, as a primary colonizer, is strongly associated with infections of (dental) implants (i.e., peri-implantitis), but little is known about the surface proteome of this bacterium. For the identification of bacterial adhesins, this study investigated the surface proteome of S. epidermidis adhering directly to titanium implant substrata. MATERIALS AND METHODS: S. epidermidis strain ATTC 35984 was cultured either planktonically or on titanium implant specimens. The surface proteomes were isolated by mutanolysin digestion, and proteins were separated by 2D gel electrophoreses to reveal highly expressed proteins only. Protein spots were visualized by silver staining and proteins were identified by mass spectrometry. RESULTS: Surface proteome analyses of S. epidermidis on titanium identified six expressed proteins. Three proteins were highly expressed on the titanium implants including accumulation-associated protein Q8CQD9. These specific proteins could be potential pathogenicity factors of bacteria in peri-implant biofilms. CONCLUSION: For the first time, our study identified S. epidermidis surface proteins, which are expressed after adhesion to titanium implant materials. CLINICAL RELEVANCE: Our study reveals possible candidates for a newly protein-based vaccine against peri-implantitis.

WNT3A and the induction of the osteogenic differentiation in adipose tissue derived mesenchymal stem cells.

Adipose tissue derived stem cells (ASCs) can easily be isolated, but the osteogenic differentiation potential is limited. To improve this differentiation potential, more investigations are required about signaling proteins for the induction of the osteogenic differentiation. This study focused on the WNT3A protein, because little is known about the canonical WNT signaling pathway and the osteogenic differentiation of ASCs. The alkaline phosphatase (ALP) activity was measured for the evaluation of the osteogenic differentiation. WNT3A and Dickkopf-related protein 1 (DKK1) were used for the activation and the inhibition of the canonical WNT signaling pathway, respectively. For control we manipulated the bone morphogenetic protein (BMP) pathway in ASCs with BMP2 and NOGGIN (BMP pathway inhibitor). WNT3A stimulated significantly the ALP activity in ASCs, while BMP2, DKK1 and NOGGIN did not induce highly the ALP activity in ASCs. Moreover, an osteogenic differentiation medium with dexamethasone and WNT3A increased the ALP activity, but the gene expression of osteoblast markers and the biomineralization after long-term cultures were not increased. In contrast, ASCs differentiated into adipocyte-like cells in all tested differentiation media. WNT3A did not repress the expression of the adipogenic transcription factor Peroxisome Proliferator-Activated Receptor Gamma (PPARG). In conclusion, WNT3A supports early stages such as the ALP activity, but it does neither improve later stages of the osteogenic differentiation nor it inhibits the genuine adipogenic differentiation of ASCs.

The influence of third molars in the line of mandibular angle fractures on wound and bone healing.

OBJECTIVES: The objective of this study was to evaluate postoperative complications after removal or retention of the third molar in the line of mandibular angle fractures. MATERIALS AND METHODS: This retrospective study included the data of 98 patients with a molar in the line of a mandibular angle fracture treated with internal reduction and mini-plate fixation at our department over 9 years. Patients were classified into two groups: tooth removal during osteosynthesis (n = 45) and tooth retention (n = 55). The primary target criterion was the incidence of minor (outpatient treatment, local measures) and major (surgical revision, rehospitalisation) complications. Time between trauma and surgery was 1.4 days (range 0 to 12), and the average follow-up 291 days (range 66 to 863). RESULTS: Regarding the eruption status, 26 of 52 (50.0 %) impacted third molars, 11 of 19 (57.9 %) incompletely erupted and 8 of 27 (29.6 %) completely erupted molars had been removed during open reduction. Overall, 17 (17.3 %) patients had postoperative minor (n = 7) or major (n = 10) complications, in detail 10/45 (22.0 %) patients after tooth removal and 7/55 (13 %) patients after tooth retention (p = 0.286). Complication rates between impacted and incompletely erupted third molars (impacted molars 15.0 %, incompletely erupted molars 10.0 %) did not differ significantly, but completely erupted molars had a complication rate of 26.0 %. CONCLUSIONS: Mandibular angle fractures with a completely erupted third molar show the highest complication rate after open reduction and osteosynthesis. Retention of a non-infectious third molar facilitates open reduction and does not increase the complication risk. CLINICAL RELEVANCE: The study helps with the decision of removing or retention of a third molar during surgical treatment of a mandibular angle fracture.

[Trauma of the midface]. / Traumatologie des Mittelgesichts.

Fractures of the midface pose a serious medical problem as for their complexity, frequency and their socio-economic impact. Interdisciplinary approaches and up-to-date diagnostic and surgical techniques provide favorable results in the majority of cases though. Traffic accidents are the leading cause and male adults in their thirties are affected most often. Treatment algorithms for nasal bone fractures, maxillary and zygoma fractures are widely agreed upon whereas trauma to the frontal sinus and the orbital apex are matter of current debate. Advances in endoscopic surgery and limitations of evidence based gain of knowledge are matters that are focused on in the corresponding chapter. As for the fractures of the frontal sinus a strong tendency towards minimized approaches can be seen. Obliteration and cranialisation seem to decrease in numbers.Some critical remarks in terms of high dose methylprednisolone therapy for traumatic optic nerve injury seem to be appropriate.Intraoperative cone beam radiographs and preshaped titanium mesh implants for orbital reconstruction are new techniques and essential aspects in midface traumatology. Fractures of the anterior skull base with cerebrospinal fluid leaks show very promising results in endonasal endoscopic repair.

The functional and aesthetic reconstruction of midfacial and orbital defects by combining free flap transfer and craniofacial prosthesis.

OBJECTIVES: The reconstruction of complex facial defects should satisfy both aesthetic and functional requirements. In the midfacial area, the nasal passage should be sufficiently separated from the orbit and the oral cavity to avoid both dysphagia and articulation disorders and to allow unimpaired nasal breathing. In the case of large defects, the use of craniofacial prostheses alone is ineffective in the restoration of functional units in the majority of patients. Therefore, we evaluated the combination of microvascular tissue transfer and episthetic constructions in a series of patients. MATERIAL AND METHODS: Our case series included ten patients requiring one or more free flaps in combination with extraoral implants and episthetic work. RESULTS: Four women and six men with a mean age of 68 years were included. All patients were treated because of tumours in the midface area. Eight patients were free of recurrence, one patient died during the follow-up. For the reconstructions, we used anterolateral thigh flaps, radial forearm flaps, fibular flaps and iliac crest bone flaps. On average, we inserted four extraoral implants in the periorbital region. Seven implants of four patients did not osseointegrate and had to be removed. CONCLUSIONS: For complex reconstructions of extensive defects in the midfacial area, microvascular free tissue transfer in combination with extraoral implants and craniofacial prosthetic work yields reasonable functional and aesthetic outcomes and noticeably improves the quality of life. CLINICAL RELEVANCE: This work investigates patient cases with extensive defects in which free flap or episthetic work alone proved ineffective for reconstruction.

A protein kinase A (PKA)/ß-catenin pathway sustains the BMP2/DLX3-induced osteogenic differentiation in dental follicle cells (DFCs).

The directed expression of osteogenic transcription factors via a balanced activation of signaling pathways is an important prerequisite for the development of mineralized tissues. A positive-feedback loop of the BMP2-dependent SMAD signaling pathway and the DLX3 transcription factor (BMP2/DLX3 pathway) directs the osteogenic differentiation of periodontal precursor cells from the dental follicle (DFCs). However, little is known how this BMP2/DLX3 pathway interacts with other crucial signaling pathways such as the WNT/ß-catenin signaling pathway. This study investigated the interaction between the BMP2/DLX3 pathway and the WNT pathway during the osteogenic differentiation of DFCs. BMP2 induced the WNT/ß-catenin pathway in DFCs and phosphorylates ß-catenin via protein kinase A (PKA). Moreover, only BMP2 facilitated the binding of LEF1/SMAD4/ß-catenin complex to the DLX3 promoter, while an inducer of the canonical WNT pathway, WNT3A, act as an inhibitor. Although WNT3A inhibits the osteogenic differentiation of DFCs the expression of ß-catenin was crucial for both the expression of DLX3 and for the osteogenic differentiation. In conclusion, while the activation of the canonical WNT pathway inhibits the osteogenic differentiation of DFCs, ß-catenin sustains the BMP2/DLX3-mediated osteogenic differentiation via the activation of PKA.

Globulomaxillary cysts--do they really exist?

OBJECTIVES: The so-called "globulomaxillary cyst", described as a fissural cyst, caused by entrapped epithelium between the nasal and maxillary process, is no longer considered for its own entity. Nevertheless, cystic lesions, which correspond to the previous image of globulomaxillary cysts, do still occur in daily practice. This raises the question to which entities pathological processes in this particular region actually belong to. MATERIALS AND METHODS: In a retrospective study, 17 cases (12 men and 5 women, 12-59 years old) of primarily diagnosed globulomaxillary cysts are analysed according to clinical, radiological and histological aspects, catamnestic processed and assigned to a new entity. The results are compared with the international literature and draws conclusions on the diagnostic and therapeutic procedure. RESULTS: Seven lateral periodontal cysts, four radicular cysts, two keratocystic odontogenic tumours, one adenomatoid odontogenic tumour, one periapical granuloma, one residual cyst and one undefined jaw cyst were determined. CONCLUSIONS: According to the results of our study and the data from the international literature, the entity globulomaxillary cyst is no longer justified.

Evaluation of single-cell biomechanics as potential marker for oral squamous cell carcinomas: a pilot study.

OBJECTIVES: Early detection of oral cancer is a major health issue. The objective of this pilot study was to analyze the deformability of healthy and cancer cells using a microfluidic optical stretcher (OS). MATERIAL AND METHODS: Different cancer cell lines, primary oral cancer cells, and their healthy counterparts were cultivated and characterized, respectively. A measurable deformation of the cells along the optical axis was detected, caused by surface stress, which is optically induced by the laser power. RESULTS: All cells revealed a viscoelastic extension behavior and showed a characteristic deformation response under laser light exposure. The CAL-27/-33 cells exhibited the highest relative deformation. All other cells achieved similar values, but on a lower level. The cytoskeleton reacts sensitively of changing environmental conditions, which may be influenced by growth behavior of the cancer specimens. Nevertheless, the statistical analysis showed significant differences between healthy and cancer cells. CONCLUSION: Generally, malignant and benign cells showed significantly different mechanical behavior. Cancer-related changes influence the composition of the cytoskeleton and thus affect the deformability, but this effect may be superimposed by cell cultivation conditions or cell doubling time. These influences had to be substituted by brush biopsies to minimize confounders in pursuing investigations.

Postoperative evaluation of microvascularization in mandibular reconstructions with microvascular flaps - first results with a new perfusion software for contrast-enhanced sonography (CEUS).

PURPOSE: Quantitative measurement of dynamic contrast values obtained by contrast-enhanced ultrasound (CEUS) for evaluating microvascularization in osseous and osseocutaneous free flaps used for maxillofacial reconstructions. PATIENTS AND METHODS: 22 patients (6 women, 16 men, mean age: 57 years, range: 47 to 82 years) who had received mandibular reconstructions with 3 avascular and 19 microvascular free osseous or osseocutaneous transplants were included in this trial. 16 patients had received a microvascular osseocutaneous fibular flap, 2 patients a microvascular osseous fibular flap and 1 patient a microvascular osseous iliac crest flap. Patients were followed up for 12 months on average (range: 3 to 20 months). Ultrasound examination was carried out by one experienced examiner with a linear probe (6-9 MHz, LOGIQ E9, GE) after the intravenous bolus injection of 2.4 ml contrast agent (SonoVue®, BRACCO, Germany). Digital cine loops were analysed with a quantification software (VueBox™) for determining wash-in parameters: Rise Time (RT), Peak Enhancement (PE), Wash-in Area Under the Curve (WiAUC) and Wash-in Rate (WiR). Results were compared with the patients' postoperative clinical outcome. RESULTS: For the bone area the median of the RT was 10.0 s (range 3.1 to 65.0 s), for the ratio between bone tissue and soft tissue for the PE the median was 10.4% (range 2.6 to 29.8%), the median for the WiAUC was 11.1% (range 1.5 to 77.7%) and the median for the WiR was 5.7 %(range 0.7 to 61.1%). None of the patients with microvascular osseocutaneous and osseous flaps showed any signs of transplant bone loss, which corresponded with the qualitative CEUS assessment. The patients with microvascular re-anastomosed transplants showed widely varying values for the investigated parameters (RT, PE, WiAUC, WiR). For patients with avascular bone transplants, these parameters were reduced to zero values for the bone area resulting in a significant difference (p < 0.05) for the PE compared to the patients with microvascular bone transplants. CONCLUSION: CEUS allowed the qualitative assessment of bone microvascularization by observing the transition of the contrast agent from the periostal area into the bone. However, defining a critical lower border by quantification of bone perfusion was difficult because of the inconstant perfusion of the bone transplants used in the trial.

[Maxillary and mandibular fractures. Treatment concepts in maxillofacial surgery]. / Frakturen von Maxilla und Mandibula. Kieferchirurgische Behandlungskonzepte.

Maxillary and mandibular fractures are a relatively frequent occurrence due to the exposed location of the jaws and are caused mainly by acts of violence, traffic and recreational accidents. Mandibular fractures can be treated conservatively with dental splints and intermaxillary fixation. Since Michelet, miniplate osteosynthesis via intraoral access has become the method of choice. Champy showed that the monocortical fixation of miniplates at the level of the linea obliqua results in stable osteosynthesis, despite postoperative micro-movements in the fracture gap, and postulated the principle of dynamic compression. Dislocated fractures of the mandibular collum are treated with stable osteosynthesis via an intra- or extraoral approach, while fractures of the mandibular joint are usually treated conservatively and early functional rehabilitation is favored. For mandibular fractures, the principle of load-bearing and load-sharing should be considered, i.e. in the case of sufficient bone and uncomplicated fractures, the bone can bear most of the force, such that miniplates are sufficient (load-sharing). If bones are weakened by atrophy or in the case of infected, comminuted or defect fractures osteosynthesis plates must bear the load alone (load-bearing).

[Current concepts in diagnosis and treatment of oral malignant tumors]. / Aktuelle Konzepte zur Früherkennung, Diagnostik und Therapie oraler Plattenepithelkarzinome.

This article offers a short review of risk factors, oral precancerous conditions, and oral precancerous lesions which may cause oral squamous carcinoma. Current diagnostic methods and multidisciplinary strategies for the early detection and appropriate therapy of oral squamous carcinomas are discussed. Close cooperation of oral and maxillofacial surgeons, head and neck surgeons, radiotherapists, and oncologists is essential for the effective therapy of oral squamous carcinomas.

Slit-2 facilitates interaction of P-cadherin with Robo-3 and inhibits cell migration in an oral squamous cell carcinoma cell line.

Slits are a group of secreted glycoproteins that act as molecular guidance cues in cellular migration. Recently, several studies demonstrated that Slit-2 can operate as candidate tumour suppressor protein in various tissues. In this study, we show Slit-2 expression in basal cell layers of normal oral mucosa colocalized with P-cadherin expression. In contrast, there is a loss of Slit-2 and P-cadherin expression in mucosa of oral squamous cell carcinoma (OSCC). Our in vitro investigations reveal a correlation of P-cadherin and Slit-2 expression: OSCC cells with induced P-cadherin expression (PCI52_PC) display an increased Slit-2 expression. However, abrogating P-cadherin function with a function-blocking antibody decreases Slit-2 secretion confirming a direct link between P-cadherin and Slit-2. Moreover, experiments with OSCC cells show that Slit-2 interferes with a Wnt related signalling pathway, which in turn affects Slit-2 expression in a feedback loop. Functionally, transwell migration assays demonstrate a Slit-2 dose-dependent decrease of PCI52_PC cell migration. However, there is no influence on migration in mock control cells. Responsible for this migration block might be an interaction of P-cadherin with Roundabout (Robo)-3, a high affinity receptor of Slit-2. Indeed, proximity ligation assays exhibit P-cadherin/Robo-3 interactions on PCI52_PC cells. Additionally, we detect a modulation of this interaction by addition of recombinant Slit-2. Down-regulation of Robo-3 expression via small interfering RNA neutralizes Slit-2 induced migration block in PCI52_PC cells. In summary, our experiments show antitumorigenic effects of Slit-2 on P-cadherin expressing OSCC cells supposedly via modulation of Robo-3 interaction.

Cancer stem cell-like cells from a single cell of oral squamous carcinoma cell lines.

Resistance of oral squamous cell carcinomas (OSCC) to conventional chemotherapy or radiation therapy might be due to cancer stem cells (CSCs). The development of novel anticancer drugs requires a simple method for the enrichment of CSCs. CSCs can be enriched from OSCC cell lines, for example, after cultivation in serum-free cell culture medium (SFM). In our study, we analyzed four OSCC cell lines for the presence of CSCs. CSC-like cells could not be enriched with SFM. However, cell lines obtained from holoclone colonies showed CSC-like properties such as a reduced rate of cell proliferation and a reduced sensitivity to Paclitaxel in comparison to cells from the parental lineage. Moreover, these cell lines differentially expressed the CSC-marker CD133, which is also upregulated in OSCC tissues. Interestingly, CD133(+) cells in OSCC tissues expressed little to no Ki67, the cell proliferation marker that also indicates reduced drug sensitivity. Our study shows a method for the isolation of CSC-like cell lines from OSCC cell lines. These CSC-like cell lines could be new targets for the development of anticancer drugs under in vitro conditions.

Assessment of bone microcirculation by contrast-enhanced ultrasound (CEUS) and [18F]-positron emission tomography/computed tomography in free osseous and osseocutaneus flaps for mandibular reconstruction: preliminary results.

PURPOSE: Postsurgical evaluation of bone microcirculation in osseous and osseocutaneus free flaps by contrast enhanced ultrasound (CEUS) with time intensity curve (TIC) analysis and [18F]-positron emission tomography/computed tomography (Fluoride-PET/CT). PATIENTS AND METHODS: 10 patients with osseous or osseocutaneus microvascular flaps were evaluated with CEUS. Ultrasound was carried out by an experienced examiner with a high resolution linear probe (6-9 MHz, LOGIQ E9, GE) after intravenous bolus injection of 2.4 ml SonoVue® (BRACCO, Germany). Time intensity curves (TIC) in selected regions of interest (ROI) were analyzed and compared with the evaluation of [18F]-positron emission tomography/computed tomography and the clinical course for at least 2 month. RESULTS: 9/10 patients showed evidence for soft tissue and osseous microcirculation of the transplants in CEUS correlating with the clinical course. The soft tissue parts of the transplant showed a mean value of 84% (range 51-98%) and the bone parts a mean value of 39% (range 11-75%) for the Area under the curve (AuC) compared with the AuC for the anastomotic vessel region. Mean values for time to peak (TTP) were 27,1 sec (range 8.7-52.0 sec) for the anastomotic vessels, 29.3 sec (range 7.9-62.0 sec) for the soft tissue of and 32.0 sec (range 7.4-69.0 sec) for the transplant bone. In 1/10 patients flap failure occurred, after denudation the bone was left as an avascular transplant. AuC showed a mean value of 0.5 % for the bone region compared with the vessel region. Fluoride-PET/CT assessed bone vitality in 7 patients as "good" in 1 patient as "uncertain" and in 1 patient as "poor". CEUS assessment was corresponding with Fluoride-PET/CT in 4 patients, clinical assessment in 6 patients. CONCLUSION: Fluoride-PET/CT is a valuable tool to make an indirect statement about the perfusion of the transplanted bone and was used as control in this study. CEUS is a new and promising method for the evaluation of microcirculation of buried free microvascular bone grafts and the osseous part of osseocutaneous flaps and may be used for a steady monitoring in the first postoperative days.