Eric Dominic Roessner

Mechanical Properties of Mesh Materials Used for Hernia Repair and Soft Tissue Augmentation

Background Hernia repair is the most common surgical procedure in the world. Augmentation with synthetic meshes has gained importance in recent decades. Most of the published work about hernia meshes focuses on the surgical technique, outcome in terms of mortality and morbidity and the recurrence rate. Appropriate biomechanical and engineering terminology is frequently absent. Meshes are under continuous development but there is little knowledge in the public domain about their mechanical properties. In the presented experimental study we investigated the mechanical properties of several widely available meshes according to German Industrial Standards (DIN ISO). Methodology/Principal Findings Six different meshes were assessed considering longitudinal and transverse direction in a uni-axial tensile test. Based on the force/displacement curve, the maximum force, breaking strain, and stiffness were computed. According to the maximum force the values were assigned to the groups weak and strong to determine a base for comparison. We discovered differences in the maximum force (11.1±6.4 to 100.9±9.4 N/cm), stiffness (0.3±0.1 to 4.6±0.5 N/mm), and breaking strain (150±6% to 340±20%) considering the direction of tension. Conclusions/Significance The measured stiffness and breaking strength vary widely among available mesh materials for hernia repair, and most of the materials show significant anisotropy in their mechanical behavior. Considering the forces present in the abdominal wall, our results suggest that some meshes should be implanted in an appropriate orientation, and that information regarding the directionality of their mechanical properties should be provided by the manufacturers.

Acellular Dermal Matrix Seeded with Autologous Fibroblasts Improves Wound Breaking Strength in a Rodent Soft Tissue Damage Model in Neoadjuvant Settings

Soft tissue defects following resectional surgery or trauma often result in deadspaces and require free or pedicled flaps. A programmed formation of filling tissue with enhanced biomechanical properties could be helpful. This study examined the effects on wound healing of acellular dermal matrix (ADM) seeded with autologous fibroblasts in a standardized rodent model. As pre- or postoperative radiotherapy is standard in many treatments of malignancies, we also investigated the effects of additional radiotherapy. Fischer rats were randomised and received a standardized unilateral soft tissue defect at the buttock. The defect was filled with ADM+fibroblasts or ADM alone. Controls received no filling. Either no radiation, adjuvant (postoperative) or neoadjuvant (preoperative) radiation was applied to the defect site. Six weeks later the defect volume was measured by MR-tomography. Wound breaking strength was examined by tensiometry according to German Industrial Standards. Filling of the defect side was significantly larger in ADM and ADM+fibroblast treated groups compared to the control group in all settings. Wound breaking strength in the unimodal setting was significantly improved in the ADM+fibroblasts group compared to the ADM group. In the neoadjuvant setting there was no significant difference between control and ADM group. However, the ADM+fibroblasts groups showed a significantly increased wound breaking strength compared to the control and the ADM-alone group. Seeded or unseeded ADM is able to fill deadspace in this rodent model in all settings. Implanting non-irradiated, vital, proliferating autologous fibroblasts on ADM results in significantly increased wound breaking strength.

Confocal laser scanning microscopy evaluation of an acellular dermis tissue transplant (Epiflex

The structure of a biological scaffold is a major determinant of its biological characteristics and its interaction with cells. An acellular dermis tissue transplant must undergo a series of processing steps, to remove cells and genetic material and provide the sterility required for surgical use. During manufacturing and sterilization the structure and composition of tissue transplants may change. The composition of the human cell-free dermis transplant Epiflex® was investigated with specific attention paid to its structure, matrix composition, cellular content and biomechanics. We demonstrated that after processing, the structure of Epiflex remains almost unchanged with an intact collagen network and extracellular matrix (ECM) protein composition providing natural cell interactions. Although the ready to use transplant does contain some cellular and DNA debris, the processing procedure results in a total destruction of cells and active DNA which is a requirement for an immunologically inert and biologically safe substrate. Its biomechanical parameters do not change significantly during the processing.

Effect of static seeding methods on the distribution of fibroblasts within human acellular dermis.

IntroductionWhen developing tissue engineered solutions for existing clinical problems, cell seeding strategies should be optimized for desired cell distribution within matrices. The purpose of this investigation was to compare the effects of different static cell seeding methods and subsequent static cell culture for up to 12 days with regard to seeding efficiency and resulting cellular distribution in acellular dermis.Materials and methodsThe seeding methods tested were surface seeding of both unmodified and mechanically incised dermis, syringe injection of cell suspension, application of low-pressure and use of an ultrasonic bath to remove trapped air. The effect of “platelet derived growth factor” (PDGF) on surface seeding and low pressure seeding was also investigated. Scaffolds were incubated for up to 12 days and were histologically examined at days 0, 4, 8 and 12 for cell distribution and infiltration depth. The metabolic activity of the cells was quantified with the MTT assay at the same time points.ResultsThe 50 ml syringe degassing procedure produced the best results in terms of seeding efficiency, cell distribution, penetration depth and metabolic activity within the measured time frame. The injection and ultrasonic bath methods produced the lowest seeding efficiency. The incision method and the 20 ml syringe degassing procedure produced results that were not significantly different to those obtained with a standard static seeding method.ConclusionWe postulate that air in the pores of the human acellular dermis (hAD) hinders cell seeding and subsequent infiltration. We achieved the highest seeding efficiency, homogeneity, infiltration depth and cell growth within the 12 day static culturing period by degassing the dermis using low- pressure created by a 50 ml syringe. We conclude that this method to eliminate trapped air provides the most effective method to seed cells and to allow cell proliferation in a natural scaffold.

Computed Tomography–Assisted Thoracoscopic Surgery: A Novel, Innovative Approach in Patients With Deep Intrapulmonary Lesions of Unknown Malignant Status

Objectives Minimally invasive resection of small, deep intrapulmonary lesions can be challenging due to the difficulty of localizing them during video-assisted thoracoscopic surgery (VATS). We report our preliminary results evaluating the feasibility of an image-guided, minimally invasive, 1-stop-shop approach for the resection of small, deep intrapulmonary lesions in a hybrid operating room (OR). Materials and Methods Fifteen patients (5 men, 10 women; mean age, 63 years) with a total of 16 solitary, deep intrapulmonary nodules of unknown malignant status were identified for intraoperative wire marking. Patients were placed on the operating table for resection by VATS. A marking wire was placed within the lesion under 3D laser and fluoroscopic guidance using a cone beam computed tomography system. Then, wedge resection by VATS was performed in the same setting without repositioning the patient. Results Complete resection with adequate safety margins was confirmed for all lesions. Marking wire placement facilitated resection in 15 of 16 lesions. Eleven lesions proved to be malignant, either primary or secondary; 5 were benign. Mean lesion size was 7.7 mm; mean distance to the pleural surface was 15.1 mm (mean lesion depth–diameter ratio, 2.2). Mean procedural time for marking wire placement was 35 minutes; mean VATS duration was 36 minutes. Conclusions Computed tomography–assisted thoracoscopic surgery is a new, safe, and effective procedure for minimally invasive resection of small, deeply localized intrapulmonary lesions. The benefits of computed tomography–assisted thoracoscopic surgery are 1. One-stop-shop procedure, 2. Lower risk for the patient (no patient relocation, no marking wire loss), and 3. No need to coordinate scheduling between the CT room and OR.

In vivo Quantification of the Effects of Radiation and Presence of Hair Follicle Pores on the Proliferation of Fibroblasts in an Acellular Human Dermis in a Dorsal Skinfold Chamber: Relevance for Tissue Reconstruction following Neoadjuvant Therapy

Introduction In neoadjuvant therapy, irradiation has a deleterious effect on neoangiogenesis. The aim of this study was to examine the post-implantation effects of neoadjuvant irradiation on the survival and proliferation of autologous cells seeded onto an acellular human dermis (hAD; Epiflex). Additionally, we examined the influence of dermal hair follicle pores on viability and proliferation. We used dorsal skinfold chambers implanted in rats and in-situ microscopy to quantify cell numbers over 9 days. Methods 24 rats received a skinfold chamber and were divided into 2 main groups; irradiated and unirradiated. In the irradiated groups 20Gy were applied epicutaneously at the dorsum. Epiflex pieces were cut to size 5x5mm such that each piece had either one or more visible hair follicle pores, or no such visible pores. Fibroblasts were transduced lentiviral with a fluorescent protein for cell tracking. Matrices were seeded statically with 2.5x104 fluorescent fibroblasts and implanted into the chambers. In each of the two main groups, half of the rats received Epiflex with hair follicle pores and half received Epiflex without pores. Scaffolds were examined in-situ at 0, 3, 6 and 9 days after transplantation. Visible cells on the surface were quantified using ImageJ. Results In all groups cell numbers were decreased on day 3. A treatment-dependent increase in cell numbers was observed at subsequent time points. Irradiation had an adverse effect on cell survival and proliferation. The number of cells detected in both irradiated and non-irradiated subjects was increased in those subjects that received transplants with hair follicle pores. Discussion This in-vivo study confirms that radiation negatively affects the survival and proliferation of fibroblasts seeded onto a human dermis transplant. The presence of hair follicle pores in the dermis transplants is shown to have a positive effect on cell survival and proliferation even in irradiated subjects.

cFLIP overexpression in T cells in thymoma-associated myasthenia gravis.

The capacity of thymomas to generate mature CD4+ effector T cells from immature precursors inside the tumor and export them to the blood is associated with thymoma‐associated myasthenia gravis (TAMG). Why TAMG(+) thymomas generate and export more mature CD4+ T cells than MG(−) thymomas is unknown.

From diagnosis to therapy in lung cancer: management of CT detected pulmonary nodules, a summary of the 2015 Chinese-German Lung Cancer Expert Panel

The first Chinese-German Lung Cancer Expert Panel was held in November 2015 one day after the 7th Chinese-German Lung Cancer Forum, Shanghai. The intention of the meeting was to discuss strategies for the diagnosis and treatment of lung cancer within the context of lung cancer screening. Improved risk classification criteria and novel imaging approaches for screening populations are highly required as more than half of lung cancer cases are false positive during the initial screening round if the National Lung Screening Trial (NLST) demographic criteria [≥30 pack years (PY) of cigarettes, age ≥55 years] are applied. Moreover, if the NLST criteria are applied to the Chinese population a high number of lung cancer patients are not diagnosed due to non-smoking related risk factors in China. The primary goal in the evaluation of pulmonary nodules (PN) is to determine whether they are malignant or benign. Volumetric based screening concepts such as investigated in the Dutch-Belgian randomized lung cancer screening trial (NELSON) seem to achieve higher specificity. Chest CT is the best imaging technique to identify the origin and location of the nodule since 20% of suspected PN found on chest X-ray turn out to be non-pulmonary lesions. Moreover, novel state-of-the-art CT systems can reduce the radiation dose for lung cancer screening acquisitions down to a level of 0.1 mSv with improved image quality to novel reconstruction techniques and thus reduce concerns related to chest CT as the primary screening technology. The aim of the first part of this manuscript was to summarize the current status of novel diagnostic techniques used for lung cancer screening and minimally invasive treatment techniques for progressive PNs that were discussed during the first Chinese-German Lung Cancer. This part should serve as an educational part for the readership of the techniques that were discussed during the Expert Panel. The second part summarizes the consensus recommendations that were interdisciplinary discussed by the Expert Panel.

Transplanted fibroblasts proliferate in host bronchial tissue and enhance bronchial anastomotic healing in a rodent model

Introduction Healing of airway anastomoses after preoperative irradiation can be a significant clinical problem. The augmentation of bronchial anastomoses with a fibroblast-seeded human acellular dermis (hAD) was shown to be beneficial, although the underlying mechanism remained unclear. Therefore, in this study we investigated the fate of the fibroblasts transplanted to the scaffold covering the anastomosis. Material and methods 32 Fisher rats underwent surgical anastomosis of the left main bronchus. In a 2 × 2 factorial design, they were randomized to receive preoperative irradiation of 20 Gy and augmentation of the anastomosis with a fibroblast-seeded transplant. Fibroblasts from subcutaneous fat of Fischer-344 rat were transduced retrovirally with tdTomato for cell tracking. After 7 and 14 days, animals were sacrificed and cell concentration of transplanted and nontransplanted fibroblasts in the hAD as well as in the bronchial tissue was measured using RT-PCR. Results Migration of transplanted fibroblasts from dermis to bronchus were demonstrated in both groups, irradiated and nonirradiated. In the irradiated groups, there was a cell count of 7 × 104 ± 1 × 104 tomato+-fibroblasts in the bronchial tissue at day 7, rising to 1 × 105 ± 1 × 104 on day 14 (p<0.0001). Tomato+-cell concentration in hAD increased from 6 × 103 ± 1 × 103 at day 7 to 6 × 104 ± 1 × 104 at day 14 (p<0.0001). In the nonirradiated groups, tomato+-cell concentration in bronchus was 4 × 103 ± 1 × 103 on day 7 and 4 × 103 ± 1 × 103 at day 14. In the hAD tomato+ cell concentration rising from 1 × 104 ± 1 × 103 at day 7 to 2 × 104 ± 3 × 103 cells at day 14 (p = 0.0028). Conclusions Transplanted fibroblasts in the irradiated groups proliferate and migrate into the irradiated host bronchial tissue, but not in the nonirradiated groups.