Skip to main content
2023 BMES Annual Meeting Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.
Back

    Tissue Engineering

    (K-415) 3D Printed System for Simultaneous Stretch and Imaging of Engineered Microtissues

    Thursday, October 12, 2023
    9:30 AM – 10:30 AM PDT
    Location: Exhibit Hall - Row K - Poster # 415
    Introduction:: Cardiac hypertrophy is a condition which can lead to arrythmias and heart failure. While genetics and chemical stress are partly responsible, mechanical stress also contributes to this pathological condition (1).  In order to investigate how mechanics interacts with genetics, we require systems to apply mechanical stresses, like stretch, to genetically defined engineered heart tissues. To capture the impact of stretch on cardiac physiology using optocardiography, this system must be small enough to easily fit under a microscope and must be easily replicated. This allows researchers to determine the consequences of mechanical load by studying how cells remodel their physiology and structure during tissue formation as well as comparing them to non-stretched tissues after tissue formation is complete. This knowledge can help researchers to develop better models of cardiac hypertrophy, leading to better approaches to manage related genetic diseases including hypertrophic and arrhythmogenic cardiomyopathy. 

    Materials and Methods::

    The stretch device and stretch chamber were created using Fusion360 computer aided design software (Figure 1). The stretch device was prototyped with polylactic acid using a fused deposition modeling technique. Hardware (bearing, screw, insert) was added to enable the device to stretch 0.2mm per revolution of the screw (Figure 2). 




     




    The stretch chambers consisted of four mounting holes around the edges and a recessed area containing four microdevices (circular wells with four upright posts each). The stretch chambers were fabricated using Hydrogel Assisted Stereolithographic Elastomer prototyping (HASTE) using agar to cast the chamber out of Sylgard 184 polydimethylsiloxane (PDMS) with a base-to-crosslinker ratio of 18:1 (2).  




     




    To begin to test the effects of stress on tissue and cell morphology, NIH 3T3 fibroblasts were seeded into collagen gel (Figure 3). The final cell concentration is 2*107 cells/mL and the final collagen (rat tail derived Collagen I, Gibco) concentration is1.5mg/mL; each device holds 7µL of gel/cell suspension. Trials were done to optimize the volumetric ratio of media to cell-laden gels to ensure cell viability and tissue formation. NucSpot Live 488 was used with a Keyence BZ 9000 E microscope to visualize the cell nuclei as the tissue developed. 




    Results, Conclusions, and Discussions:: A stretch system composed of a PLA stretch device and PDMS stretch chamber was successfully created. Fusion 360 modeling showed that forces exerted on the stretch chamber by the device were applied evenly and there was an equal stress distribution during the stretch process (Figure 1). The total system cost is under $30 and the system allows for live imaging of microtissues during the stretch. The system can be stretched to 77±20% strain before failure, well above the range of typical commercial strain devices. A successful prototype for the stretch system was developed and has the potential to enhance research on the linkage between mechanical stretch and genotype-phenotype differences in genetic conditions causing cardiac hypertrophy and fibrosis. 

    Acknowledgements (Optional): : This work was supported by the NSF Center for Engineering Mechanobiology (CMMI:15-48571) 

    References (Optional): :



    1. (1) Ruwhof, C., & van der Laarse, A. (2000). Mechanical stress-induced cardiac hypertrophy: mechanisms and signal transduction pathways. Cardiovascular research, 47(1), 23–37. https://doi.org/10.1016/s0008-6363(00)00076-6 








    1. (2) Simmons, D. W., Schuftan, D. R., Ghiska Ramahdita, & Huebsch, N. (2023). Hydrogel-Assisted Double Molding Enables Rapid Replication of Stereolithographic 3D Prints for Engineered Tissue Design. ACS Applied Materials & Interfaces, 15(21). https://doi.org/10.1021/acsami.3c02279