Fibroblast-seeded collagen gels in response to dynamic equibiaxial mechanical stimuli: A biomechanical study |
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| Affiliation: | 1. Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan;2. Department of Orthopedics Surgery, Show Chwan Memorial Hospital, Changhua, Taiwan;3. Department of Mechanical Engineering, National Chiao Tung University, Hsinchu, Taiwan;4. Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan;1. Istituto Gas Ionizzati del CNR, Padova, Italy;2. Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova, Italy;3. Department of Molecular Medicine, University of Padova, Padova, Italy;4. Department of Biomedical Sciences, University of Padova, Italy;5. Department of Ophthalmology, S. Antonio Hospital, Padova, Italy;6. Department of Neuroscience, Ophthalmology Unit, University of Padova, Padova, Italy;1. Key Laboratory of Digital Earth, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, PR China;2. College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai 201306, PR China;3. College of Engineering, Peking University, Beijing 100871, PR China;4. Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA;1. School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China;2. School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an, 710049, China;1. International Center for Applied Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi''an Jiaotong University, Xi''an, China;2. Institute of Biomechanics and Medical Engineering, Department of Engineering Mechanics, Tsinghua University, Beijing, China;3. School of Engineering, Brown University, Providence, Rhode Island;1. International Center for Applied Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace, Xi’an Jiaotong University, Xi’an, China;2. Institute of Biomechanics and Medical Engineering, Department of Engineering Mechanics, Tsinghua University, Beijing, China;3. School of Engineering, Brown University, Providence, Rhode Island |
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| Abstract: | The remodeling of fibroblast-seeded collagen gels in response to dynamic mechanical stimuli was investigated by using a newly developed biaxial culture system capable of cyclically stretching planar soft tissues. Fibroblast-seeded collagen gels were subjected to three distinct dynamic mechanical conditions for six days: Cyclic Equibiaxial Stretching at two constant strain magnitudes (CES-7% and CES-20%), and Cyclic Equibiaxial Stretching with incrementally Increasing stain magnitude (ICES, 7% → 15% → 20% each for two days). The frequency of cyclic stretching was set at 1 Hz. At the end of culture, mechanical properties of the gels were examined by biaxial mechanical testing and checked again upon the removal of seeded cells. Collagen microstructure within the gels was illustrated by multiphoton microscopy. The mRNA levels of collagen type I and type III and fibronectin in the cells were examined by reverse transcription PCR. The protein expression of α-smooth muscle actin was detected by immunohistochemistry. We found that the gels cultured under cyclic stretching were stiffer than those cultured under static stretching. Particularly, the stiffness appeared to be significantly enhanced when the ICES was employed. The enhancement of mechanical properties by cyclic stretching appeared to persist upon cell removal, suggesting an irreversible remodeling of extracellular matrix. Second harmonic generation images showed that collagen fibers became thicker and more compact in the gels cultured under cyclic stretching, which may explain the mechanical findings. The mRNA expression of collagen type I in the cells of the ICES was significantly greater than that of the other groups except for the CES-20%. This study suggests that when cyclic stretching is to be used in engineering soft tissues, incrementally increasing strain magnitude may prove useful in the development of the tissue. |
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| Keywords: | Fibroblast-seeded collagen gels 3D cell culture Cyclic stretching Bioreactor Mechanical properties Mechanobiology |
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