Ultrastructure of Proteoglycans in Tissue-Engineered Cardiovascular Structures

Abstract

Proteoglycans such as versican, decorin, and perlecan are important components of the extracellular matrix in various tissues. They play an important role in water homeostasis, tissue elasticity, prevention of calcification, and thrombogenicity. The aim of our study was to detect such proteoglycans in engineered tissue and compare them with the proteoglycans of native porcine heart valves. Myofibroblasts were seeded on a type I collagen scaffold. Thereafter, endothelial cells were seeded onto the presettled myofibroblasts. The newly formed tissue was histologically and immunohistochemically examined. Cupromeronic blue was used for ultracytochemical staining of proteoglycans. Radiolabeled proteoglycans were isolated by ion-exchange chromatography and characterized by enzymatic degradation. Three differently sized proteoglycan precipitates were found. The large-sized proteoglycan (154 nm) was located outside the collagen bundles in a rarely structured extracellular matrix compound. The small-sized proteoglycan (46 nm) was aligned along the collagen bundles at intervals of 60 nm. The intermediate-sized proteoglycan (56 nm) was detected on the cell surface of myofibroblasts. The glycosaminoglycans included 80% chondroitin and dermatan sulfate and 20% heparan sulfate. We conclude that proteoglycans play an important role in the functional integrity of cardiovascular tissues. This study shows the successful production of a heart valve-like tissue with proteoglycans resembling, in terms of type, production, and distribution, proteoglycans of native heart valves.

Cell Projections and Extracellular Matrix Cross the Interstitial Interface within the Renal Stem/Progenitor Cell Niche: Accidental, Structural or Functional Cues?

“…For the current investigation, conventional fixation in glutaraldehyde (GA) and improved fixation were applied as introduced years ago for the analysis of ECM in mouse tectorial membrane [17] and proteoglycans in cardiovascular structures [18]. Techniques were performed without modifications to recognize masked ECM within the renal stem/progenitor cell niche.…”

Heart Valve Tissue Engineering

“…113 Anseth and colleagues have used crosslinked polyvinylalcohol 114 and hyaluronan as a substrate for valve tissue engineering. 115,116 Rothenburger and colleagues from Muenster, Germany, have used collagen films as scaffolds for tissue engineering 117,118 and found that myofibroblasts and endothelium cocultured produced significant amounts of collagen and structural proteoglycans. Fibrin is being considered an alternative to collagen in valvular tissue engineering by a number of groups, 119 including that of Tranquillo.…”

Valve proteoglycan content and glycosaminoglycan fine structure are unique to microstructure, mechanical load and age: Relevance to an age-specific tissue-engineered heart valve

“…Proteoglycans (PGs) and glycosaminoglycans (GAGs) are critical to the function of numerous soft connective tissues, including heart valves, providing material properties such as viscoelasticity and resistance to compression and tension [1,2]. PGs and GAGs also play crucial roles in tissue differentiation, growth factor regulation and various pathologies [2].…”

“…PGs and GAGs also play crucial roles in tissue differentiation, growth factor regulation and various pathologies [2]. During fetal development, PGs and GAGs are the predominant components of the nascent heart valves [3].…”