The effects of a simple optical clearing protocol on the mechanics of collagenous soft tissue

JOURNAL OF BIOMECHANICS

卷:122

Article

Meador, William D.¹  Zhou, Jennifer¹  Malinowski, Marcin^2,3  Jazwiec, Tomasz^2,4  Calve, Sarah⁵  Timek, Tomasz A.²  Rausch, Manuel K.^1,6,7 

[1] Univ Texas Austin, Dept Biomed Engn, Austin, TX 78712 USA

[2] Spectrum Hlth, Div Cardiothorac Surg, Grand Rapids, MI USA

[3] Med Univ Silesia, Sch Med Katowice, Dept Cardiac Surg, Katowice, Poland

[4] Med Univ Silesia, Silesian Ctr Heart Dis, Dept Cardiac Vasc & Endovasc Surg & Transplantol, Zabrze, Poland

[5] Univ Colorado, Dept Mech Engn, Boulder, CO 80309 USA

[6] Univ Texas Austin, Dept Aerosp Engn & Engn Mech, Austin, TX 78712 USA

[7] Univ Texas Austin, Oden Inst Computat Engn & Sci, Austin, TX 78712 USA

关键词: Two-photon;    Microscopy;    Multi-scale;    Biaxial;    Leaflet;   

DOI  :  10.1016/j.jbiomech.2021.110413

来源: Elsevier

【 摘 要 】

Optical clearing of biological tissues improves imaging depth for light transmission imaging modalities such as two-photon microscopy. In studies that investigate the interplay between microstructure and tissue-level mechanics, mechanical testing of cleared tissue may be useful. However, the effects of optical clearing on soft tissue mechanics have not been investigated. Thus, we set out to quantify the effects of a simple and effective optical clearing protocol on the mechanics of soft collagenous tissues using ovine mitral valve anterior leaflets as a model system. First, we demonstrate the effectiveness of an isotonic glycerol-DMSO optical clearing protocol in two-photon microscopy. Second, we evaluate the mechanical effects of optical clearing on leaflets under equibiaxial tension in a dependent study design. Lastly, we quantify the shrinkage strain while traction-free and the contractile forces while constrained during clearing. We found the optical clearing protocol to improve two-photon imaging depth from similar to 100 mu m to similar to 500-800 mu m, enabling full-thickness visualization of second-harmonic generation, autofluorescent, and fluorophore-tagged structures. Under equibiaxial tension, cleared tissues exhibited reduced circumferential (p < 0.001) and radial (p = 0.009) transition stretches (i.e. stretch where collagen is recruited), and reduced radial stiffness (p = 0.031). Finally, during clearing we observed similar to 10-15% circumferential and radial compressive strains, and when constrained, similar to 2 mN of circumferential and radial traction forces. In summary, we suggest the use of this optical clearing agent with mechanical testing be done with care, as it appears to alter the tissue's stress-free configuration and stiffness, likely due to tissue dehydration. (C) 2021 Elsevier Ltd. All rights reserved.

【 授权许可】

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