Optical metrics of the extracellular matrix predict compositional and mechanical changes after myocardial infarction.
Understanding the organization and mechanical function of the extracellular matrix (ECM) is critical for the development of therapeutic strategies that regulate wound healing following disease or injury. However, these relationships are challenging to elucidate during remodeling following myocardial infarction (MI) due to rapid changes in cellularity and an inability to characterize both ECM microstructure and function non-destructively. In this study, we overcome those challenges through whole organ decellularization and non-linear optical microscopy to directly relate the microstructure and mechanical properties of myocardial ECM. We non-destructively quantify collagen organization, content, and cross-linking within decellularized healthy and infarcted myocardium using second harmonic generation (SHG) and two photon excited autofluorescence. Tensile mechanical testing and compositional analysis reveal that the cumulative SHG intensity within each image volume and the average collagen autofluorescence are significantly correlated with collagen content and elastic modulus of the ECM, respectively. Compared to healthy ECM, infarcted tissues demonstrate a significant increase in collagen content and fiber alignment, and a decrease in cross-linking and elastic modulus. These findings indicate that cross-linking plays a key role in stiffness at the collagen fiber level following infarction, and highlight how this non-destructive approach to assessing remodeling can be used to understand ECM structure-function relationships.
Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA.|Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, 72701, USA.
Kyle P
KP
Quinn
Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA.
Kelly E
KE
Sullivan
Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA.
Zhiyi
Z
Liu
Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA.
Zachary
Z
Ballard
Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA.|Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, 54124, Greece.
Christos
C
Siokatas
Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA.
Irene
I
Georgakoudi
Department of Biomedical Engineering, Tufts University, Medford, MA, 02155, USA.|Cellular, Molecular, and Developmental Biology Program, Sackler School for Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA.
Lauren D
LD
Black
D000818:Animals; D005109:Extracellular Matrix / Q000378:metabolism / Q000473:pathology; D008297:Male; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D009203:Myocardial Infarction / Q000378:metabolism / Q000473:pathology; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley