Quantitative assessment of myocardial collagen with picrosirius red staining and circularly polarized light

Abstract

Collagen plays a major role in the structural organization of the heart and therefore direct visualization of collagen fibers is a crucial component of cardiac analysis. Although linearly polarized light has proven an effective tool for the examination of myocardial collagen in histologic sections, the use of circularly polarized light may offer advantages and additional possibilities. We examined the potential enhancement of collagen analysis using circularly polarized light in two ways. We first measured the brightness, and hence indirectly assessed the birefringence, of collagen fibers in scars examined at different times after myocardial infarction. Secondly, we measured collagen content in myocardial tissue and compared results obtained from brightfield analysis of trichrome stained sections with those obtained from circularly polarized light analysis of picrosirius red stained sections. We observed a progressive increase in the maximum brightness of collagen fibers in the scar with time, and a time-dependent shift in the relative distribution of collagen fiber brightness from lower to higher levels. We found consistently lower values of collagen content in trichrome stained versus picrosirius red stained tissue, and concluded that trichrome staining underestimated collagen content. The information provided by these studies could not be obtained by brightfield analysis and could be only partially obtained from linearly polarized light analysis. Thus, analysis using circularly polarized light has the ability to enhance histologic assessment of tissue and can provide additional insights into the composition and structure of myocardial collagen.

Interstitial Fibrosis Restricts Osmotic Water Transport in Encapsulating Peritoneal Sclerosis

“…Of note, similar changes in collagen content and optical properties have been evidenced as part of the scarring process after myocardial infarction. 18,19,27 The data presented here show that fibrotic changes in the peritoneum of patients on long-term PD closely correlate with impaired water transport across the membrane, thereby confirming the hypothesis that structural changes in the peritoneal interstitium account for the excessive reduction in osmotic conductance. 28 The interstitium, which is mainly composed of collagen and glycosaminoglycans, constitutes a porous matrix across which interstitial fluid flows.…”

Collagenous Fibril Texture of the Discoid Lateral Meniscus

“…Sirius red is specific for collagen, and the stained collagen appeared in yellow, red/orange, or green, according to their direction under polarizing filter light microscopy [20][21][22] ; thus, the collagenous fibrils are easily discriminated.…”

American Thyroid Association Guide to Investigating Thyroid Hormone Economy and Action in Rodent and Cell Models

“…It should be noted that the conditions of fixing cardiac tissue can affect cardiomyocyte morphology and additional methods have been developed to determine accurately myocyte cross-sectional area as well as length (539). Masson's trichrome staining of sections is used to assess fibrosis in combination with cardiomyocyte morphology (542), and the collagen volume fraction may be quantified by picrosirius-red staining and polarized-light microscopy (568). Expression of T 3 target genes, including Hcn2, Kcne1, Kcnb1, Kcna1, Kcnq1, Thra, Thrb (534), Atp2a2, Myh6, Myh7 (62,238), and Nppa (238), is performed by RT-qPCR on mRNA extracted either from whole heart or from individual chambers or regions (see Section I.2 for technical considerations).…”