A model to determine the effect of collagen fiber alignment on heart function post myocardial infarction

Introduction: Despite various clinical modalities, ischemic heart disease remains among the leading causes of mortality and morbidity worldwide. The elemental problem is the immense loss of cardiomyocytes (CMs) post-myocardial infarction (MI). Reprogramming non- cardiomyocytes (non-CMs) into cardiomyocyte (CM)-like cells in vivo is a promising strategy for cardiac regeneration: however, the traditional viral delivery method hampered its application into clinical settings due to low and erratic transduction efficiency. Methods: We used a modified mRNA (modRNA) gene delivery platform to deliver different stoichiometry of cardiac-reprogramming genes (Gata4, Mef2c, Tbx5 and Hand2) together with reprogramming helper genes (Dominant Negative (DN)-TGFβ, DN- Wnt8a and Acid ceramidase (AC)), named 7G, to induce direct cardiac reprogramming post myocardial infarction (MI). Results: Here, we identified 7G modRNA cocktail as an important regulator ofthe cardiac reprogramming. Cardiac transfection with 7G modRNA doubled cardiac reprogramming efficiency (57%) in comparison to Gata4, Mef2C and Tbx5 (GMT) alone (28%) in vitro . By inducing MI in our lineage tracing model, we showed that one-time delivery of the 7G-modRNA cocktail reprogrammed ~25% of the non-CMs in the scar area to CM- like cells. Furthermore, 7G modRNA treated mice showed significantly improved cardiac function, longer survival, reduced scar size and greater capillary density than control mice 28 days post-MI. We attributed the improvement in heart function post modRNA delivery of 7G or 7G with increased Hand2 ratio (7G-GMT Hx2) to significant upregulation of 15 key angiogenic factors without any signs of angioma or edema. Conclusions: 7G or 7G GMT HX2 modRNA cocktails boosts de novo CM-like cells and promotes cardiovascular regeneration post-MI. Thus, we highlight that this gene delivery approach not only has high efficiency but also high margin of safety for translation to clinics.

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Collagen Fiber Alignment and Maximum Principal Strain in the Glenohumeral Capsule Predict Location of Failure During Uniaxial Extension

ASME 2011 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2011-53492 ◽

2011 ◽

Author(s):

Kelvin Luu ◽

Carrie A. Voycheck ◽

Patrick J. McMahon ◽

Richard E. Debski

Keyword(s):

Collagen Fiber ◽

Glenohumeral Joint ◽

Uniaxial Extension ◽

Principal Strain ◽

Fiber Alignment ◽

Glenohumeral Ligament ◽

Maximum Principal Strain ◽

Inferior Glenohumeral Ligament ◽

Glenohumeral Capsule ◽

Collagen Fiber Alignment

The glenohumeral joint is frequently dislocated causing injury to the glenohumeral capsule (axillary pouch (AP), anterior band of the inferior glenohumeral ligament (AB-IGHL), posterior band of the inferior glenohumeral ligament (PB-IGHL), posterior (Post), and anterosuperior region (AS)). [1, 2] The capsule is a passive stabilizer to the glenohumeral joint and primarily functions to resist dislocation during extreme ranges of motion. [3] When unloaded, the capsule consists of randomly oriented collagen fibers, which play a pertinent role in its function to resist loading in multiple directions. [4] The location of failure in only the axillary pouch has been shown to correspond with the highest degree of collagen fiber orientation and maximum principle strain just prior to failure. [4, 5] However, several discrepancies were found when comparing the collagen fiber alignment between the AB-IGHL, AP, and PB-IGHL. [3,6,7] Therefore, the objective was to determine the collagen fiber alignment and maximum principal strain in five regions of the capsule during uniaxial extension to failure and to determine if these parameters could predict the location of tissue failure. Since the capsule functions as a continuous sheet, we hypothesized that maximum principal strain and peak collagen fiber alignment would correspond with the location of tissue failure in all regions of the glenohumeral capsule.

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Rapid Quantification of 3D Collagen Fiber Alignment and Fiber Intersection Correlations with High Sensitivity

PLoS ONE ◽

10.1371/journal.pone.0131814 ◽

2015 ◽

Vol 10 (7) ◽

pp. e0131814 ◽

Cited By ~ 19

Author(s):

Meng Sun ◽

Alexander B. Bloom ◽

Muhammad H. Zaman

Keyword(s):

Collagen Fiber ◽

High Sensitivity ◽

Fiber Alignment ◽

3D Collagen ◽

Collagen Fiber Alignment ◽

Rapid Quantification

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P2Y12 antagonists and cardiac repair post-myocardial infarction: global and regional heart function analysis and molecular assessments in pigs

Cardiovascular Research ◽

10.1093/cvr/cvy201 ◽

2018 ◽

Vol 114 (14) ◽

pp. 1860-1870 ◽

Cited By ~ 15

Author(s):

Gemma Vilahur ◽

Manuel Gutiérrez ◽

Laura Casani ◽

Carmen Lambert ◽

Guiomar Mendieta ◽

...

Keyword(s):

Myocardial Infarction ◽

Function Analysis ◽

Heart Function ◽

Cardiac Repair ◽

Post Myocardial Infarction ◽

P2y12 Antagonists

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Effect of Preconditioning on Collagen Fiber Recruitment: Inhomogeneous Properties of Rat Supraspinatus Tendon

ASME 2010 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2010-19089 ◽

2010 ◽

Author(s):

Kristin S. Miller ◽

Lena Edelstein ◽

Louis J. Soslowsky

Keyword(s):

Mechanical Properties ◽

Collagen Fiber ◽

Insertion Site ◽

Supraspinatus Tendon ◽

Fiber Alignment ◽

Rigorous Evaluation ◽

Structural Alterations ◽

Testing Protocol ◽

Inhomogeneous Properties ◽

Collagen Fiber Alignment

Cyclic preconditioning is a commonly accepted initial component of any tendon testing protocol. Preconditioning provides tendons with a consistent “history” and stress-strain results become repeatable allowing for rigorous evaluation and comparison. While it is widely accepted that preconditioning is important, changes that occur during preconditioning are not well understood. Micro-structural alterations, such as re-arrangement of collagen fibers, is one proposed mechanism of preconditioning [1,4]. However, this mechanism has not been examined. Therefore, the objective of this study is to locally measure: 1) fiber re-alignment during preconditioning, stress relaxation and tensile testing and 2) corresponding mechanical properties, to address mechanisms of preconditioning as well as tissue nonlinearity and inhomogeneity in the rat supraspinatus tendon. We hypothesize that 1) fiber re-alignment will be greatest in the toe region, but will also occur during preconditioning and 2) mechanical properties and initial collagen fiber alignment will be greater in the midsubstance location of the tendon compared to the tendon-to-bone insertion site.

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Collagen Fiber Re-Alignment and Mechanical Properties in a Mouse Supraspinatus Tendon Model: Examining Changes With Age and Location

ASME 2012 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2012-80017 ◽

2012 ◽

Cited By ~ 1

Author(s):

Kristin S. Miller ◽

Brianne K. Connizzo ◽

Elizabeth Feeney ◽

Louis J. Soslowsky

Keyword(s):

Mechanical Properties ◽

Collagen Fiber ◽

Mechanical Load ◽

Mechanical Test ◽

Insertion Site ◽

Supraspinatus Tendon ◽

Tissue Response ◽

Mechanical Stimuli ◽

Fiber Alignment ◽

Collagen Fiber Alignment

One postulated mechanism of tendon structural response to mechanical load is collagen fiber re-alignment. Recently, where collagen fiber re-alignment occurs during a tensile mechanical test has been shown to vary by tendon age and location in a postnatal developmental mouse supraspinatus tendon (SST) model [1]. It is thought that as the tendon matures and its collagen fibril network, collagen cross-links and collagen-matrix interactions develop, its ability to respond quickly to mechanical stimuli hastens [1]. Additionally, the insertion site and midsubstance of postnatal SST may develop differently and at different rates, providing a potential explanation for differences in fiber re-alignment behaviors at the insertion site and midsubstance at postnatal developmental time points [1]. However, collagen fiber re-alignment behavior, in response to mechanical load at a mature age and in comparison to developmental ages, have not been examined. Therefore, the objectives of this study are to locally measure: 1) fiber re-alignment during preconditioning and tensile mechanical testing and 2) to compare local differences in collagen fiber alignment and corresponding mechanical properties to address tissue response to mechanical load in the mature and postnatal developmental mouse SST. We hypothesize that 1) 90 day tendons will demonstrate the largest shift in fiber re-alignment during preconditioning, but will also re-align during the toe- and linear-regions. Additionally, we hypothesize that 2) mechanical properties and initial collagen fiber alignment will be greater in the midsubstance of the tendon compared to the tendon-to-bone insertion site at 90 days, 3) that mechanical properties will increase with age, and that 4) collagen fiber organization at the insertion site will decrease with age.

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