[Intraoperative quality management modalities in head and neck surgery]. / Intraoperative Modalitäten zur Qualitätssicherung in der Kopf­Hals­Chirurgie.

Immediate intraoperative control via suitable imaging techniques is necessary to achieve the best possible surgical outcome. Intraoperative imaging increases patient safety, offers the surgeon direct support in challenging anatomic regions, and affords the possibility of direct correction with a reduced rate of corrective surgery. The procedures are based on cone beam computed tomography (CBCT), endoscopy, or navigation-assisted surgery. This article describes available intraoperative quality management modalities for fracture management and tumor treatment in the field of head and neck surgery.

Comparison of virtual and titanium clip marking of tumour resection margins for improved radiation planning in head and neck cancer surgery.

Communication between the surgeon and the radiation oncologist is improved with the use of virtual models of the final tumour resection, combining three-dimensional imaging and conventional clip marking with computer-aided navigation. This investigation was designed to determine the deviation of virtual marking procedures compared to conventional marking by titanium ligature clips in oral cancer with different localizations. Seventeen patients with surgically placed clips and virtual landmarks on the resection margin after complete tumour ablation were evaluated. To determine whether the virtual landmarks remain predictive of the resection margin, the deviation of the virtual points from their corresponding clips was analyzed by measuring the distance between their centres of gravity. In total, 189 clips were evaluated. Metric analyses of the deviation between the virtual points and clips showed a deviation of 2.3 ± 0.6mm for tumours with a maxilla localization, 7.2 ± 2.5mm for tumours with a mandible localization, and 12.6 ± 3.8mm for tumours with a tongue localization. A significant statistical relationship was demonstrated in the virtual point-clip deviation as a function of tumour localization. Virtual marking of maxillary tumour resection margins allows accurate definition of the former tumour bed and could lead to novel adjuvant treatment strategies.

In vivo comparison of hard tissue regeneration with ovine mesenchymal stem cells processed with either the FICOLL method or the BMAC method.

INTRODUCTION: The aim of this work was to analyse the suitability of mesenchymal stem cell isolation by FICOLL density centrifugation and the closed bone marrow aspirate concentrate (BMAC) system for sinus augmentation with bovine bone mineral (BBM) in the sheep model. METHODS: 16 sheep underwent sinus augmentation with BBM and MSCs; they were divided between two groups with survival points of 8 and 16 weeks. For the FICOLL control arm three, and for the BMAC test arm, five augmentations were performed for each time point. The derived cell numbers were counted; a colony forming unit (CFU) assay was performed; the pluripotency of the MSCs was proved; histological and histomorphometrical analysis were performed. RESULTS: The approach of using BBM and MSCs in combination with fibrin adhesive was sufficient for new bone formation as the FICOLL experiment indicated. However, due to significantly lower cell numbers isolated using the BMAC in sheep, less new bone was formed in the test arm. CONCLUSIONS: The BMAC system is well suited for human MSC isolation but it needs to be optimized to fit sheep cell characteristics if it is to be used in this animal model.

3D scaffolds co-seeded with human endothelial progenitor and mesenchymal stem cells: evidence of prevascularisation within 7 days.

Blood supply is a critical issue in most tissue engineering approaches for large defect healing. As vessel ingrowth from surrounding tissues is proven to be insufficient, current strategies are focusing on the neo-vascularisation process. In the present study, we developed an in vitro pre-vascularised construct using 3D polyurethane (PU) scaffolds, based on the association of human Endothelial Progenitor Cells (EPC, CD34+ and CD133+) with human Mesenchymal Stem Cells (MSC). We showed the formation of luminal tubular structures in the co-seeded scaffolds as early as day 7 in culture. These tubular structures were proven positive for endothelial markers von Willebrand Factor and PECAM-1. Of special significance in our constructs is the presence of CD146-positive cells, as a part of the neovasculature scaffolding. These cells, coming from the mesenchymal stem cells population (MSC or EPC-depleted MSC), also expressed other markers of pericyte cells (NG2 and αSMA) that are known to play a pivotal function in the stabilisation of newly formed pre-vascular networks. In parallel, in co-cultures, osteogenic differentiation of MSCs occurred earlier when compared to MSCs monocultures, suggesting the close cooperation between the two cell populations. The presence of angiogenic factors (from autologous platelet lysates) in association with osteogenic factors seems to be crucial for both cell populations' cooperation. These results are promising for future clinical applications, as all components (cells, growth factors) can be prepared in an autologous way.