Secreted Endothelial Cell Factors Immobilized on Collagen Scaffolds Enhance the Recipient Endothelial Cell Environment

Strategies to design novel vascular scaffolds are a continuing aim in tissue engineering and often such designs encompass the use of recombinant factors to enhance the performance of the scaffold. The established use of cell secretion utilized in feeder systems and conditioned media offer a source of paracrine factors, which has potential to be used in tissue-engineered (TE) scaffolds. Here we utilize this principle from endothelial cells (ECs), to create a novel TE scaffold by harnessing secreted factors and immobilizing these to collagen scaffolds. This research revealed increased cellular attachment and positive angiogenic gene upregulation responses in recipient ECs grown on these conditioned scaffolds. Also, the conditioning method did not affect the mechanical structural integrity of the scaffolds. These results may advocate the potential use of this system to improve vascular scaffolds' in vivo performance. In addition, this process may be a future method utilized to improve other tissue engineering scaffold therapies

EDC/NHS cross-linked collagen foams as scaffolds for artificial corneal stroma.

International audienceIn this study, a highly porous collagen-based biodegradable scaffold was developed as an alternative to synthetic, non-degradable corneal implants. The developed method involved lyophilization and subsequent stabilization through N-ethyl-N'-[3-dimethylaminopropyl] carbodiimide/N-hydroxy succinimide (EDC/NHS) cross-linking to yield longer lasting, porous scaffolds with a thickness similar to that of native cornea (500 microm). For collagen-based scaffolds, cross-linking is essential; however, it has direct effects on physical characteristics crucial for optimum cell behavior. Hence, the effect of cross-linking was studied by examining the influence of cross-linking on pore size distribution, bulk porosity and average pore size. After seeding the foam with human corneal keratocytes, cell proliferation, cell penetration into the scaffold and ECM production within the scaffold were studied. After a month of culture microscopical and immunohistochemical examinations showed that the foam structure did not undergo any significant loss of integrity, and the human corneal keratocytes populated the scaffold with cells migrating both longitudinally and laterally, and secreted some of the main constituents of the corneal ECM, namely collagen types I, V and VI. The foams had a layer of lower porosity (skin layer) both at the top and the bottom. Foams had an optimal porosity (93.6%), average pore size (67.7 microm), and chemistry for cell attachment and proliferation. They also had a sufficiently rapid degradation rate (73.6+/-1.1% in 4 weeks) and could be produced at a thickness close to that of the natural corneal stroma. Cells were seeded at the top surface of the foams and their numbers there was higher than the rest, basically due to the presence of the skin layer. This is considered to be an advantage when epithelial cells need to be seeded for the construction of hemi or full thickness cornea.In this study, a highly porous collagen-based biodegradable scaffold was developed as an alternative to synthetic, non-degradable corneal implants. The developed method involved lyophilization and subsequent stabilization through N-ethyl-N'-[3-dimethylaminopropyl] carbodiimide/N-hydroxy succinimide (EDC/NHS) cross-linking to yield longer lasting, porous scaffolds with a thickness similar to that of native cornea (500 microm). For collagen-based scaffolds, cross-linking is essential; however, it has direct effects on physical characteristics crucial for optimum cell behavior. Hence, the effect of cross-linking was studied by examining the influence of cross-linking on pore size distribution, bulk porosity and average pore size. After seeding the foam with human corneal keratocytes, cell proliferation, cell penetration into the scaffold and ECM production within the scaffold were studied. After a month of culture microscopical and immunohistochemical examinations showed that the foam structure did not undergo any significant loss of integrity, and the human corneal keratocytes populated the scaffold with cells migrating both longitudinally and laterally, and secreted some of the main constituents of the corneal ECM, namely collagen types I, V and VI. The foams had a layer of lower porosity (skin layer) both at the top and the bottom. Foams had an optimal porosity (93.6%), average pore size (67.7 microm), and chemistry for cell attachment and proliferation. They also had a sufficiently rapid degradation rate (73.6+/-1.1% in 4 weeks) and could be produced at a thickness close to that of the natural corneal stroma. Cells were seeded at the top surface of the foams and their numbers there was higher than the rest, basically due to the presence of the skin layer. This is considered to be an advantage when epithelial cells need to be seeded for the construction of hemi or full thickness cornea

Student Perceptions of a New Course Using Argumentation in Medical Education

Andrew J Foy,1,2,* Kent E Vrana,3 Paul Haidet,1,2 Bernice L Hausman,2,4 Nancy E Adams,5 Ira Ropson,6 Daniel R Wolpaw,1 David Rabago,2,7 Richard B Mailman,3,8 Xuemei Huang3,8– 10,* 1Penn State Department of Medicine, Penn State Milton S Hershey Medical Center and College of Medicine, Hershey, PA, USA; 2Penn State Department of Public Health Science, Penn State Milton S Hershey Medical Center and College of Medicine, Hershey, PA, USA; 3Penn State Department of Pharmacology, Penn State Milton S Hershey Medical Center and College of Medicine, Hershey, PA, USA; 4Penn State Department of Humanities, Penn State Milton S Hershey Medical Center and College of Medicine, Hershey, PA, USA; 5Harrel Library Foundational Sciences, Penn State Milton S Hershey Medical Center and College of Medicine, Hershey, PA, USA; 6Penn State Department of Biochemistry and Molecular Biology, Penn State Milton S Hershey Medical Center and College of Medicine, Hershey, PA, USA; 7Penn State Department of Family and Community Medicine, Penn State Milton S Hershey Medical Center and College of Medicine, Hershey, PA, USA; 8Penn State Department of Neurosurgery, Penn State Milton S Hershey Medical Center and College of Medicine, Hershey, PA, USA; 9Penn State Department of Neurology, Penn State Milton S Hershey Medical Center and College of Medicine, Hershey, PA, USA; 10Penn State Department of Kinesiology, Penn State Milton S Hershey Medical Center and College of Medicine, Hershey, PA, USA*These authors contributed equally to this workCorrespondence: Andrew J Foy, Penn State Milton S Hershey Medical Center and College of Medicine, Penn State Heart and Vascular Institute, Division of Cardiology, Hershey, PA, USA, Email [email protected]: Critical thinking and the ability to engage with others of differing views in a civil manner is essential to the practice of medicine. A new format for medical student education (“Argue-to-Learn”) that uses staged debates followed by small group discussions was introduced into the curriculum of first year medical school at the Penn State College of Medicine. The goal was to create a structured environment for spirited, civil discourse, and to encourage students to think critically about clinically controversial topics. This manuscript describes the development of the program, and presents comparative data on student perceptions of the first two mandatory sessions that focused on the treatment of post-menopausal osteoporosis and on COVID-19 vaccine mandates.Methods: Quantitative results were gathered from standardized post-block student surveys for each session and compared to cumulative results of all other courses included in the learning block. Post-block surveys of students include four session-evaluation questions scored on a 5 point Likert scale. Scores were compared using Student’s t-test. Thematic analysis of qualitative data was performed on a single open-ended response from the same survey.Results: Compared to all other courses in the learning block, scores on each of the four questions were either the same or numerically higher for the Argue-to-Learn sessions, but none reached statistical significance. Two important qualitative themes were identified. First, students enjoyed the format, found it interesting and engaging and want more similar sessions. Second, students appreciated hearing opposing viewpoints and presenting their own viewpoints in a safe and supportive environment.Conclusion: These findings support evidence from educational scholarship outside of medicine showing argumentation as a learning tool is well received by students. Further work is needed to determine whether it improves critical thinking skills and enhances learning in medical education.Keywords: argumentation, critical discourse, collaborative learnin

Manufacture and characterisation of EmDerm—novel hierarchically structured bio-active scaffolds for tissue regeneration

There are significant challenges for using emulsion templating as a method of manufacturing macro-porous protein scaffolds. Issues include protein denaturation by adsorption at hydrophobic interfaces, emulsion instability, oil droplet and surfactant removal after protein gelation, and compatible cross-linking methods. We investigated an oil-in-water macro-emulsion stabilised with a surfactant blend, as a template for manufacturing protein-based nano-structured bio-intelligent scaffolds (EmDerm) with tuneable micro-scale porosity for tissue regeneration. Prototype EmDerm scaffolds were made using either collagen, through thermal gelation, fibrin, through enzymatic coagulation or collagen-fibrin composite. Pore size was controlled via surfactant-to-oil phase ratio. Scaffolds were crosslink-stabilised with EDC/NHS for varying durations. Scaffold micro-architecture and porosity were characterised with SEM, and mechanical properties by tensiometry. Hydrolytic and proteolytic degradation profiles were quantified by mass decrease over time. Human dermal fibroblasts, endothelial cells and bone marrow derived mesenchymal stem cells were used to investigate cytotoxicity and cell proliferation within each scaffold. EmDerm scaffolds showed nano-scale based hierarchical structures, with mean pore diameters ranging from 40–100 microns. The Young’s modulus range was 1.1–2.9 MPa, and ultimate tensile strength was 4–16 MPa. Degradation rate was related to cross-linking duration. Each EmDerm scaffold supported excellent cell ingress and proliferation compared to the reference materials Integra™ and Matriderm™. Emulsion templating is a novel rapid method of fabricating nano-structured fibrous protein scaffolds with micro-scale pore dimensions. These scaffolds hold promising clinical potential for regeneration of the dermis and other soft tissues, e.g., for burns or chronic wound therapies