Summary In order to investigate the effects of collagen peptide ingestion on fibroblasts and the extracellular matrix in the dermis, collagen peptide was administered orally to pigs at 0.2 g/kg body weight/d for 62 d, and its effects were compared with those of lactalbumin and water controls. Fibroblast density, and diameter and density of collagen fibrils were significantly larger in the collagen peptide group than in the lactalbumin and water control groups. The two major components of dermal glycosaminoglycans, hyaluronic acid and dermatan sulfate, which are present in the inter-fibrillar space, did not differ significantly among the three groups. However, the ratio of dermatan sulfate, which is derived from fibrilbound decorin, was largest in the collagen peptide group. These results suggest that ingestion of collagen peptide induces increased fibroblast density and enhances formation of collagen fibrils in the dermis in a protein-specific manner. Key Words collagen peptide, dermis, collagen fibril, glycosaminoglycan, electron microscopyThe skin is the largest organ in the human body and protects the body from various external insults. Skin comprises two layers, the epidermis and the dermis, consisting of stratified squamous epithelium and connective tissues, respectively. The dermis contains large amounts of extracellular matrix (ECM) components, such as collagen and glycosaminoglycans (GAG), mainly produced by fibroblasts ( 1 ). Collagen is the most abundant protein in the vertebrate body, comprising approximately 30% of the total protein. To date, over 20 types of collagen genes have been identified, and these are divided into three groups: fibrous collagen, fibrilassociated collagen and basement membrane collagen ( 2 ). In the dermis, type I collagen forms collagen fibrils that are further organized into collagen fibers in association with other types of fibrous or fibril-associated collagen ( 3 ). The size of collagen fibrils is an important factor that determines the physical nature of tissue, as collagen fibrils/fibers form the framework of the vertebrate body ( 4 ). The size of collagen fibrils varies depending on tissue type and physiological conditions ( 5 ). Their diameters are reportedly regulated, for example, by the content of collagen types III or V or other types of non-fibrous collagen. Rates of synthesis and degradation of collagen also probably determine the size of collagen fibrils ( 6 , 7 ).GAG consists of repeating two-sugar units and, with the exception of hyarulonic acid (HA), exists in tissue as proteoglycans that form covalent bonds with core proteins ( 8 ). The dermatan sulfate (DS) proteoglycan decorin is located on the surface of collagen fibrils and regulates their size ( 9 ). On the other hand, HA is highly hydrophilic and forms a gel with large amounts of water, playing a role in resisting external mechanical stresses ( 8 , 10 ). The change in the ratio of HA affects the diameter of the collagen fibrils ( 11 ). Thus, the size of collagen fibrils and the amount of GAG, such as ...
ABSTRACT. The distribution pattern of collagen fibril diameter in the equine superficial digital flexor tendon (SDFT) is known to differ in central and peripheral areas of some regions. This study reports the essence of collagen fibril differences among different regions of the equine SDFT by transmission electron microscopic (TEM) and high-voltage electron microscopic observations and biochemical analysis. The distribution of large collagen fibrils increased but the density of collagen fibrils decreased from the proximal metacarpal region to the distal metacarpal region. Large collagen fibrils with an irregular cross-sectional profile were found more frequently in the middle metacarpal region than in other regions. Three-dimensional reconstruction of images of irregularly shaped collagen fibrils revealed that these fibrils are formed through fusion of small collagen fibrils with large ones. The amount of decorin, which reportedly inhibits the lateral fusion of collagen fibrils, decreased in the direction of the distal metacarpal region. On the other hand, the size of decorin gradually increased in the direction of the distal metacarpal region. These results suggest that regional differences in collagen fibril distribution and density of collagen fibrils in the SDFT are due, at least in part, to fusion of collagen fibrils and the concomitant regional differences in the amount and size of decorin. KEY WORDS: assembly, collagen, decorin, equine, superficial digital flexor tendon.
The present study was carried out to determine the effect of decorin in the process of collagen assembly. Collagen fibrils were obtained in vitro by aggregation from commercialized acid-soluble type I collagen with the addition of different concentrations of decorin (0-25 microg/ml). All specimens were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The distribution of collagen fibril diameters was also analyzed by TEM. In samples without or with low concentrations of decorin, highly porous collagen fiber networks were formed. On the other hand, dense networks were observed in samples treated with high concentrations of decorin. The influence of decorin secreted by cells on collagen fibrils was observed by SEM, and the fiber network elasticity was measured using a rheometer. SEM images showed that collagen fiber networks without fibroblasts were much looser than those cultured with normal fibroblasts. The networks cultured with the fibroblasts were composed of straight fibers with large diameters. On the other hand, collagen fiber networks cultured with siRNA-decorin-transfected (siDT) fibroblasts had loose, meandering fibers with small diameters. The elasticity of collagen fiber networks cultured with untransfected fibroblasts showed no significant difference over the 7-day incubation period. However, significantly lower elastic values were obtained for collagen fiber networks treated with siDT cells on days 3 and 7. In addition, after treatment with 5.0 or 25 microg/ml decorin, the l collagen fiber networks cultured with siDT cells exhibited an altered structure that showed a dense structure similar to that of the fiber networks cultured with untransfected fibroblasts. In conclusion, this in vitro study showed that decorin is a regulatory and architecturally small leucine-rich repeat proteoglycan in the process of collagen fibril assembly.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.