Search for: All records

Recreating articular cartilage tri-layered patterning for an engineered in vitro cell construct holds promise for advancing cartilage repair efforts. Our approach involves the development of a mul-tichambered perfusion tissue bioreactor that regulates fluid shear stress levels similar to the gradated hydrodynamic environment in articular cartilage. COMSOL modeling reveals our ta-pered cell chamber design will produce three different shear levels, high in the 22 – 41 mPa range, medium in the 4.5 – 8.4 mPa range, and low in the 2.2 – 3.8 mPa range and distributed across the surface of our mesenchymal stromal cell (MSC) encapsulated construct. In a 14-day bioreactor culture, we assess how fluid shear magnitude and cell vertical location within a 3D construct influence cell chondrogenesis. Notably, Sox9 expression for MSCs cultivated in our reactor shows spatially patterned gene upregulations coding for key chondrogenic marker pro-teins. Beginning with the high shear stress region, lubricin and type II collagen gene increases of 410 and 370-fold indicate cell movement towards a superficial zone architype which is further supported by histological and immunohistochemical stains illustrating the formation of a dense proteoglycan matrix enriched with lubricin, versican, and collagen types I and II molecules. For the medium shear stress region high aggrecan and type II collagen gene expressions of 2.3 and 400-fold, respectively, along with high proteoglycan analyses show movement toward a superfi-cial/mid-zone cartilage architype. For low shear stress regions higher collagen types II and X gene upregulations of 550 and 8,300-fold, the latter being 2x of that for the high shear regime, indicate cell movement with deep zone characteristics. Collectively, biochemical analysis, histol-ogy, and gene expression data demonstrated that our fluid shear bioreactor induced a stratified structure within tissue engineered constructs, demonstrating the feasibility of using this ap-proach to recapitulate the structure of native articular cartilage. 

Not AActive, hands-on learning is essential for engineering education, fostering deep engagement and enhancing knowledge retention. This multi-institutional study investigates how different instructional methods—Hands-On, Virtual, and Lecture-only—combined with four distinct Low-Cost Desktop Learning Modules (LCDLMs: Hydraulic Loss, Double Pipe, Shell & Tube, and Venturi Meter) affect student engagement and learning outcomes. Anchored in the ICAP framework (Interactive, Constructive, Active, Passive), the study measured cognitive engagement through direct observations, virtual screen recordings, and self-reported surveys. It assessed learning gains using normalized pre- and post-tests among 2,316 undergraduate engineering students from eight universities. Results indicate that virtual instruction yields significantly higher learning gains, while the Shell & Tube module enhances active engagement through tangible, hands-on experiences. In contrast, the Hydraulic Loss module demonstrates the greatest impact on quantitative knowledge growth. These findings underscore the potential of integrating virtual simulations with physical learning tools to optimize instructional design in engineering education. Implications for future research include refining measurement instruments and exploring the long-term effects of hybrid instructional models. 

Over the past seven years, our team has disseminated low-cost hands-on learning hardware and associated worksheets in fluid mechanics and heat transfer to provide engineering students with an interactive learning experience. Previous studies have shown (1-5) the efficacy of teaching students with an active learning approach versus a more traditional lecture setup, with a number of approaches already available, such as simple active discussion, think-pair-share, flipped classrooms, etc. Our approach is differentiated by the inclusion of hardware to add both a visual aid and an opportunity for hands-on experimentation while keep the costs low enough for a classroom setting. Learning with a hands-on, interactive approach is supported by social cognitive theory (SCT) (6-7) and information processing theory (8). Unlike earlier views of learning theory, which simply posit that the key to learning is repetition, social cognitive theory considers the agency of the student and the social aspects of learning. The primary assumption of SCT is that students are active participants in the learning process, acquiring and displaying knowledge, skills, and behaviors that align with their goals through a process called triadic reciprocal causation, illustrated in figure 1.