A Qualitative Histological Comparison of Collagen Deposition Between a Diseased and Healthy Cadaveric Heart

Date

2023

Authors

Shah, Krusha
Snyder, Alyssa
Markgraf, Jon Michael
Sarathy, Swathi
Kronser, Leo
Crowe, Nicole

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Abstract

Purpose: Fibrosis is a pathological process characterized by the overproduction of extracellular matrix (ECM), especially collagen. Type I collagen is the most abundant structural protein found in ECM and serves as an indicator for fibrosis. Although increased collagen accumulation is considered a normal aspect of aging, excessive collagen accumulation is also a notable hallmark observed in chronic cardiovascular disease. Numerous studies have examined collagen deposition using animal models and pathologic human cardiac tissue. However, few studies have investigated the normal accumulation of collagen in healthy human hearts. This study aims to perform a qualitative comparison of collagen deposition between a diseased and healthy human heart.

Methods and Results: This study utilized two hearts from cadaveric donors, one designated "diseased” and the other "healthy”. Each heart originated from a female in their 6th decade of life and had a body mass index within the normal range (18.5-24.9 kg/m2). The donor with the "diseased” heart had a known history of heart disease. Furthermore, gross examination revealed the "diseased” heart was enlarged (mass: 458.5 g; normal range: 230-290 g), had severe coronary artery disease, contained two implanted coronary artery grafts, and demonstrated left ventricular wall hypertrophy (thickness: 2.0 cm; normal thickness: ≤1.5 cm). In contrast, the donor with the "healthy” heart had no known history of heart disease and showed no visible signs of disease. Tissue samples were collected from the right ventricle, interventricular septum, and left ventricle from each heart and underwent routine histological preparation with Masson’s trichrome staining. Microscopic observation was performed to determine the pattern of collagen deposition within each section, classified as interstitial-perimyocyte, replacement, or mixed. Additionally, the location of collagen in each section of the ventricular wall was noted as being primarily within the inner 50% (endocardial side), outer 50% (epicardial side), or diffuse. To assess the reliability and repeatability of this study, an analysis of intra- and interobserver error will be conducted by the authors. Preliminary findings suggest the amount and patterns of collagen differs between the two hearts.

Conclusion: In this study, histology was used to qualitatively analyze the differences in collagen deposition between a diseased and healthy human heart. These findings highlight the importance of conducting a comprehensive study that examines the normal accumulation of collagen in healthy human hearts. Gaining an in-depth understanding of how collagen accumulates normally is critical for recognizing disease related changes.

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Research Appreciation Day Award Winner - Texas College of Osteopathic Medicine, 2023 Medical Student Government Association Best in First Year Class

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