James A. Kaupp

Genipin Cross-Linked Fibrin Hydrogels for in vitro Human Articular Cartilage Tissue-Engineered Regeneration

Our objective was to examine the potential of a genipin cross-linked human fibrin hydrogel system as a scaffold for articular cartilage tissue engineering. Human articular chondrocytes were incorporated into modified human fibrin gels and evaluated for mechanical properties, cell viability, gene expression, extracellular matrix production and subcutaneous biodegradation. Genipin, a naturally occurring compound used in the treatment of inflammation, was used as a cross-linker. Genipin cross-linking did not significantly affect cell viability, but significantly increased the dynamic compression and shear moduli of the hydrogel. The ratio of the change in collagen II versus collagen I expression increased more than 8-fold over 5 weeks as detected with real-time RT-PCR. Accumulation of collagen II and aggrecan in hydrogel extracellular matrix was observed after 5 weeks in cell culture. Overall, our results indicate that genipin appeared to inhibit the inflammatory reaction observed 3 weeks after subcutaneous implantation of the fibrin into rats. Therefore, genipin cross-linked fibrin hydrogels can be used as cell-compatible tissue engineering scaffolds for articular cartilage regeneration, for utility in autologous treatments that eliminate the risk of tissue rejection and viral infection.

Mechanical Stimulation of Chondrocyte-agarose Hydrogels

Articular cartilage suffers from a limited repair capacity when damaged by mechanical insult or degraded by disease, such as osteoarthritis. To remedy this deficiency, several medical interventions have been developed. One such method is to resurface the damaged area with tissue-engineered cartilage; however, the engineered tissue typically lacks the biochemical properties and durability of native cartilage, questioning its long-term survivability. This limits the application of cartilage tissue engineering to the repair of small focal defects, relying on the surrounding tissue to protect the implanted material. To improve the properties of the developed tissue, mechanical stimulation is a popular method utilized to enhance the synthesis of cartilaginous extracellular matrix as well as the resultant mechanical properties of the engineered tissue. Mechanical stimulation applies forces to the tissue constructs analogous to those experienced in vivo. This is based on the premise that the mechanical environment, in part, regulates the development and maintenance of native tissue(1,2). The most commonly applied form of mechanical stimulation in cartilage tissue engineering is dynamic compression at physiologic strains of approximately 5-20% at a frequency of 1 Hz(1,3). Several studies have investigated the effects of dynamic compression and have shown it to have a positive effect on chondrocyte metabolism and biosynthesis, ultimately affecting the functional properties of the developed tissue(4-8). In this paper, we illustrate the method to mechanically stimulate chondrocyte-agarose hydrogel constructs under dynamic compression and analyze changes in biosynthesis through biochemical and radioisotope assays. This method can also be readily modified to assess any potentially induced changes in cellular response as a result of mechanical stimuli.

Development of the Transferable Learning Orientations Tool: Providing Metacognitive Opportunities and Meaningful Feedback for Students and Instructors.

This study encapsulates the development and testing of the Transferable Learning Orientations (TLO) tool. It is a triangulated measure built on select scales from the Motivated Strategies for Learning Questionnaire (MSLQ), together with multiple-choice items adapted from the lifelong learning VALUE rubric, and an open-ended response for each dimension. Select scales from the MSLQ were tested in a range of undergraduate courses, and the TLO (version one) was developed and piloted in a first-year engineering course. Minor refinements were made, and the TLO (version two) was retested with second-year undergraduates. The TLO is designed to engage students in meta-cognitive processes and provide meaningful feedback to students. The dimensions are outcome motivation, learning belief, self-efficacy, transfer and organisation. Results from the second-year group were more consistent and reliable than the first-year group, suggesting that context is an important factor. The scales demonstrate acceptable reliability, and the moderate correlations between scale scores and rubric ratings provide support for concurrent validity. We recommend the TLO be tested with broader populations to confirm psychometric properties and that it be implemented longitudinally to investigate the development of learning skills and changes in orientations over time.

Formative feedback and scaffolding for developing complex problem solving and modelling outcomes

ABSTRACT This paper discusses the use and impact of formative feedback and scaffolding to develop outcomes for complex problem solving in a required first-year course in engineering design and practice at a medium-sized research-intensive Canadian university. In 2010, the course began to use team-based, complex, open-ended contextualised problems to develop problem solving, communications, teamwork, modelling, and professional skills. Since then, formative feedback has been incorporated into: task and process-level feedback on scaffolded tasks in-class, formative assignments, and post-assignment review. Development in complex problem solving and modelling has been assessed through analysis of responses from student surveys, direct criterion-referenced assessment of course outcomes from 2013 to 2015, and an external longitudinal study. The findings suggest that students are improving in outcomes related to complex problem solving over the duration of the course. Most notably, the addition of new feedback and scaffolding coincided with improved student performance.

Contents Vol. 190, 2009

F. Beck, Leicester A.L. Boskey, New York, N.Y. R.C. Burghardt, College Station, Tex. G. Burnstock, London F. Eckstein, Salzburg A.C. Enders, Davis, Calif. C. Farnum, Ithaca, N.Y. R.H.W. Funk, Dresden N.E. Fusenig, Heidelberg A. Gibson, Phoenix, Ariz. M. Glickstein, London J.W. Hermanson, Ithaca, N.Y. C.J. Kirkpatrick, Mainz P. Köpf-Maier, Berlin W. Kummer, Giessen J.W. Lichtman, Cambridge, Mass. K.G. Marra, Pittsburgh, Pa. O. Ohtani, Toyama P.J. Reier, Gainesville, Fla. R. Roy, Los Angeles, Calif. R. Segal, Chapel Hill, N.C. F. Sinowatz, Munich M. Sittinger, Berlin T. Skutella, Tübingen G.B. Stark, Freiburg i.Br. E. Th ompson, Melbourne C.G. Widmer, Gainesville, Fla. in vivo, in vitro