Evaluation of 3D hepatic tissue models for bioprinting

Introduction: Drug-induced liver injury is the leading cause of acute liver failure and post-market drug withdrawals. In vivo animal studies cannot be totally translated to humans; therefore, there’s huge demand of novel in vitro human models. 3D culture conditions would increase models longevity while bioprinting technology is expected to improve their functionality by the in vivo-like cell spatial patterning. Aim: The present project aims at the establishment and characterization of printed liver tissue-like models as co-culture of human cells such as hepatocytes, stellate and endothelial cells in order to reproduce a functional liver sinusoid. 3D equivalents were printed to assess hepatic cells printability (printing test), while high-density hepatocytes models were manually produced and characterized in order to simulate in-vivo cellular density conditions and define experimental parameters for bioprinting process. Materials and methods: - Printing test: HepG2 cells were mixed 6*106 cells/ml with bioink, PEG-based ink produced in house. Matrigel solution was added to further improve cell viability during the printing process. Cell mixture was printed by direct dispensing in a spiral pattern and polymerized at 365nm wavelength. Models were analysed up to 7 days for cell proliferation, viability and morphology. - High-density 3D models: High-density HepG2 discs and drop models were manually produced mixing 2:1 HepG2 “paste” with ink (supplemented with matrigel). Models were polymerized by exposure to 365nm wavelength for few seconds and cultivated up to 28 days. The equivalents were analysed for cell viability and albumin secretion as well as processed for histological analyses (cell proliferation, tissue-like intercellular tight junctions and lipid storage investigation). Results and discussion: - Bioprinting as well as ink is suitable for HepG2 viability and proliferation up to 7 days (15.84 ± 1.46 fold change increase day 7 vs day1). Printed HepG2 are homogenously distributed and round-shaped, forming agglomerates that increase in size over time. - HepG2-ink-matrigel equivalents are long-term stable characterized by high and constant cell viability up to 28 days. The models resemble native liver with respect to the high cell density and due to the ink supplementation can easily be printed into tissue-like models with exact cell patterning and defined structure. Models are currently under investigation for tissue functionality and morphology and will be subsequently printed. Conclusions: Bioprinting shows high potential for the manufacture of high-density liver tissue-like models. The printing of different cell types (hepatocytes, stellate and endothelial cells) will allow producing organotypical 3D liver equivalents

Tissue Engineering - the gateway to regenerative medicine

Tissue Engineering as an emerging biotechnology sector aims at the in vitro regeneration of diseased tissues and promises to profoundly change medical practice, offering the possibility of regenerating tissues and organs instead of just repairing them (regenerative medicine). Improved healing processes and a higher quality of life are the expected results. This article gives an overview of different technologies for regenerative medicine and presents results of our own current applied research and development. A recent project was successfully closed with the development of a natural biomaterial for soft tissue oral defects. The establishment of an in vitro bioreactor system enabled us to simulate the mechanical and biological environment in a healing wound and to investigate the suitability of different implant materials for the oral tissue regeneration. Moreover, focusing the attention on an alternative method for the intervertebral disc (IVD) regeneration, we established a new tissue engineered approach, based on the three-dimensional (3D) culture of autologous human IVD cells into a polyurethane (PU)-fibrin composite. IVD cells were able to proliferate and, thanks to the 3D conditions, to differentiate expressing the typical native tissue markers. The development of an automated platform was the goal of an additional project, to standardize the cell culture technology, increase the bio-safety and reduce the production costs, moving tissue engineering nearer to clinical application

Label free non-invasive imaging of topically applied actives in reconstructed human epidermis by confocal Raman spectroscopy

Raman spectroscopy has become a versatile tool for the in vivo charaterisation of skin. Here we describe use of Raman spectroscopy for high resolution optical cross sectioning to resolve skin constituents and administered drugs at the cellular level. Percutaneous penetration is typically studied using permeation cells with biopsies of animals or human skin. Although this technique provides valuable clinical data, little insight is gained in the microstructure of drug penetration (intercellular or transcellular) or in the mode of action of applied vehicles or penetration enhancers. Therefore, a Raman microspectroscopic method was combined with a confocal scanning setup to image the microstructure of commercially available skin models (SkinEthic®) and the spatial distribution of penetrated actives. The models’ microstructure was scanned without any special treatment or environment such as cutting, staining, freezing, or application of vacuum. The non-invasive Raman images reveal the layered structure of stratum corneum. This in particular for lipids while water tends to be more evenly distributed. When penetration of the hydrophilic active glycerol and the lipophilic octyl methoxycinnamate, OMC, was studied, a strong correlation between the local distribution of skin constituents and the hydrophilic/lipophilic character of the active was observed

Efficacy and safety of P11-4 for the treatment of periodontal defects in dogs

Objectives: This study's aim was to investigate the safety and performance of a self-assembling peptide matrix (SAPM) P11-4 for the treatment of periodontal disease in a controlled pre-clinical study. Materials and methods: Acute buccal bony dehiscence defects (LxW: 5 × 3 mm) were surgically created on the distal root of four teeth on one mandible side of 7 beagle dogs followed by another identical surgery 8 weeks later on the contralateral side. SAPM P11-4 (with and without root conditioning with 24% EDTA (T1, T2)), Emdogain® (C) and a sham intervention (S) were randomly applied on the four defects at each time point. Four weeks after the second surgery and treatment, the animals were sacrificed, the mandibles measured by micro-computed tomography (µ-CT) and sections of the tissue were stained and evaluated histologically. Results: Clinically and histologically, no safety concerns or pathological issues due to the treatments were observed in any of the study groups at any time point. All groups showed overall similar results after 4 and 12 weeks of healing regarding new cementum, functionality of newly formed periodontal ligament and recovery of height and volume of the new alveolar bone and mineral density. Conclusion: A controlled clinical study in humans should be performed in a next step as no adverse effects or safety issues, which might affect clinical usage of the product, were observed. Clinical relevance: The synthetic SAPM P11-4 may offer an alternative to the animal-derived product Emdogain® in the future

Development and application of a 3D periodontal in vitro model for the evaluation of fibrillar biomaterials

Background: Periodontitis is a chronic inflammation of the tooth supporting structures that finally can lead to tooth loss. As chronic periodontitis is associated with systemic diseases multiple approaches have been followed to support regeneration of the destructed tissue. But very few materials are actually used in the clinic. A new and promising group of biomaterials with advantageous biomechanical properties that have the ability to support periodontal regeneration are self-assembling peptides (SAP). However, there is still a lack of 3D periodontal models that can evaluate the migration potential of such novel materials. Methods: All experiments were performed with primary human periodontal ligament fibroblasts (HPLF). Migration capacity was assessed in a three-dimensional model of the human periodontal ligament by measuring the migration distance of viable cells on coated (Enamel Matrix Protein (EMP), P11–4, collagen I) or uncoated human dentin. Cellular metabolic activity on P11–4 hydrogels was assessed by a metabolic activity assay. Deposition of ECM molecules in a P11–4 hydrogel was visualized by immunostaining of collagen I and III and fibrillin I. Results: The 3D periodontal model was feasible to show the positive effect of EMP for periodontal regeneration. Subsequently, self-assembling peptide P11–4 was used to evaluate its capacity to support regenerative processes in the 3D periodontal model. HPLF coverage of the dentin surface coated with P11–4 increased significantly over time, even though delayed compared to EMP. Cell viability increased and inclusion of ECM proteins into the biomaterial was shown. Conclusion: The presented results indicate that the 3D periodontal model is feasible to assess periodontal defect coverage and that P11–4 serves as an efficient supporter of regenerative processes in the periodontal ligament. Clinical relevance: The establishment of building-block synthetic polymers offers new opportunities for clinical application in dentistry. Self-assembling peptides represent a new generation of biomaterials as they are able to respond dynamically to the changing environment of the biological surrounding. Especially in the context of peri-implant disease prevention and treatment they enable the implementation of new concepts

Health technology assessment of public health interventions: an analysis of characteristics and comparison of methods-study protocol

Mathes T, Willms G, Polus S, et al. Health technology assessment of public health interventions: an analysis of characteristics and comparison of methods-study protocol. SYSTEMATIC REVIEWS. 2018;7(1): 79.Background: Conducting a health technology assessment (HTA) of public health interventions (PHIs) poses some challenges. PHIs are often complex interventions, which affect the number and degree of interactions of the aspects to be assessed. Randomized controlled trials on PHIs are rare as they are difficult to conduct because of ethical or feasibility issues. The aim of this study is to provide an overview of the methodological characteristics and to compare the applied assessment methods in HTAs on PHIs. Methods: We will systematically search HTA agencies for HTAs on PHIs published between 2012 and 2016. We will identify the HTAs by screening the webpages of members of international HTA organizations. One reviewer will screen the list of HTAs on the webpages of members of international HTA organization, and a second review will double-check the excluded records. For this methodological review, we define a PHI as a population-based intervention on health promotion or for primary prevention of chronic or non-chronic diseases. Only full HTA reports will be included. At maximum, we will include a sample of 100 HTAs. In the case that we identify more than 100 relevant HTAs, we will perform a random selection. We will extract data on effectiveness, safety and economic as well as on social, cultural, ethical and legal aspects in a priori piloted standardized tables. We will not assess the risk of bias as we focus on exploring methodological features. Data extraction will be performed by one reviewer and verified by a second. We will synthesize data using tables and in a structured narrative way. Discussion: Our analysis will provide a comprehensive and current overview of methods applied in HTAs on PHIs. We will discuss approaches that may be promising to overcome the challenges of evaluating PHIs

Efficacy and safety of P11-4 for the treatment of periodontal defects in dogs

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)Objectives: This study’s aim was to investigate the safety and performance of a self-assembling peptide matrix (SAPM) P11-4 for the treatment of periodontal disease in a controlled pre-clinical study. Materials and methods: Acute buccal bony dehiscence defects (LxW: 5 × 3 mm) were surgically created on the distal root of four teeth on one mandible side of 7 beagle dogs followed by another identical surgery 8 weeks later on the contralateral side. SAPM P11-4 (with and without root conditioning with 24% EDTA (T1, T2)), Emdogain® (C) and a sham intervention (S) were randomly applied on the four defects at each time point. Four weeks after the second surgery and treatment, the animals were sacrificed, the mandibles measured by micro-computed tomography (µ-CT) and sections of the tissue were stained and evaluated histologically. Results: Clinically and histologically, no safety concerns or pathological issues due to the treatments were observed in any of the study groups at any time point. All groups showed overall similar results after 4 and 12 weeks of healing regarding new cementum, functionality of newly formed periodontal ligament and recovery of height and volume of the new alveolar bone and mineral density. Conclusion: A controlled clinical study in humans should be performed in a next step as no adverse effects or safety issues, which might affect clinical usage of the product, were observed. Clinical relevance: The synthetic SAPM P11-4 may offer an alternative to the animal-derived product Emdogain® in the future