Development of Tissue-Engineered Ligaments: Elastin Promotes Regeneration of the Rabbit Medial Collateral Ligament.

When ligaments are injured, reconstructive surgery is sometimes required to restore function. Methods of reconstructive surgery include transplantation of an artificial ligament and autotransplantation of a tendon. However, these methods have limitations related to the strength of the bone-ligament insertion and biocompatibility of the transplanted tissue after surgery. Therefore, it is necessary to develop new reconstruction methods and pursue the development of artificial ligaments. Elastin is a major component of elastic fibers and ligaments. However, the role of elastin in ligament regeneration has not been described. Here, we developed a rabbit model of a medial collateral ligament (MCL) rupture and treated animal knees with exogenous elastin [100 µg/(0.5 mL·week)] for 6 or 12 weeks. Elastin treatment increased gene expression and protein content of collagen and elastin (gene expression, 6-fold and 42-fold, respectively; protein content, 1.6-fold and 1.9-fold, respectively), and also increased the elastic modulus of MCL increased with elastin treatment (2-fold) compared with the controls. Our data suggest that elastin is involved in the regeneration of damaged ligaments.

Elastin hydrolysate derived from fish enhances proliferation of human skin fibroblasts and elastin synthesis in human skin fibroblasts and improves the skin conditions.

BACKGROUND: Recent studies have shown that certain peptides significantly improve skin conditions, such as skin elasticity and the moisture content of the skin of healthy woman. This study aimed to investigate the effects of elastin hydrolysate on human skin. Proliferation and elastin synthesis were evaluated in human skin fibroblasts exposed to elastin hydrolysate and proryl-glycine (Pro-Gly), which is present in human blood after elastin hydrolysate ingestion. We also performed an ingestion test with elastin hydrolysate in humans and evaluated skin condition. RESULTS: Elastin hydrolysate and Pro-Gly enhanced the proliferation of fibroblasts and elastin synthesis. Maximal proliferation response was observed at 25 ng mL(-1) Pro-Gly. Ingestion of elastin hydrolysate improved skin condition, such as elasticity, number of wrinkles, and blood flow. Elasticity improved by 4% in the elastin hydrolysate group compared with 2% in the placebo group. CONCLUSION: Therefore, elastin hydrolysate activates human skin fibroblasts and has beneficial effects on skin conditions.

Preparation of photocrosslinked fish elastin polypeptide/microfibrillated cellulose composite gels with elastic properties for biomaterial applications.

Photocrosslinked hydrogels reinforced by microfibrillated cellulose (MFC) were prepared from a methacrylate-functionalized fish elastin polypeptide and MFC dispersed in dimethylsulfoxide (DMSO). First, a water-soluble elastin peptide with a molecular weight of ca. 500 g/mol from the fish bulbus arteriosus was polymerized by N,N'-dicyclohexylcarbodiimide (DCC), a condensation reagent, and then modified with 2-isocyanatoethyl methacrylate (MOI) to yield a photocrosslinkable fish elastin polypeptide. The product was dissolved in DMSO and irradiated with UV light in the presence of a radical photoinitiator. We obtained hydrogels successfully by substitution of DMSO with water. The composite gel with MFC was prepared by UV irradiation of the photocrosslinkable elastin polypeptide mixed with dispersed MFC in DMSO, followed by substitution of DMSO with water. The tensile test of the composite gels revealed that the addition of MFC improved the tensile properties, and the shape of the stress-strain curve of the composite gel became more similar to the typical shape of an elastic material with an increase of MFC content. The rheology measurement showed that the elastic modulus of the composite gel increased with an increase of MFC content. The cell proliferation test on the composite gel showed no toxicity.

Architecture of the subendothelial elastic fibers of small blood vessels and variations in vascular type and size.

Most blood vessels contain elastin that provides the vessels with the resilience and flexibility necessary to control hemodynamics. Pathophysiological hemodynamic changes affect the remodeling of elastic components, but little is known about their structural properties. The present study was designed to elucidate, in detail, the three-dimensional (3D) architecture of delicate elastic fibers in small vessels, and to reveal their architectural pattern in a rat model. The fine vascular elastic components were observed by a newly developed scanning electron microscopy technique using a formic acid digestion with vascular casts. This method successfully visualized the 3D architecture of elastic fibers in small blood vessels, even arterioles and venules. The subendothelial elastic fibers in such small vessels assemble into a sheet of meshwork running longitudinally, while larger vessels have a higher density of mesh and thicker mesh fibers. The quantitative analysis revealed that arterioles had a wider range of mesh density than venules; the ratio of density to vessel size was higher than that in venules. The new method was useful for evaluating the subendothelial elastic fibers of small vessels and for demonstrating differences in the architecture of different types of vessels.

Identification of food-derived elastin peptide, prolyl-glycine (Pro-Gly), in human blood after ingestion of elastin hydrolysate.

Elastin hydrolysate has apparent beneficial effects, and the food-derived peptide prolyl-glycine (Pro-Gly) is present in human blood after oral ingestion. Following ingestion of elastin hydrolysate (10 g/60 kg body weight) by healthy human volunteers, peripheral blood was used to prepare plasma samples from which peptides were extracted by solid phase extraction and fractionated by size-exclusion chromatography (SEC). Peptides in the SEC fractions were derivatized with phenyl isothiocyanate (PITC) and resolved by reversed phase (RP)-HPLC. Pro-Gly was the major food-derived elastin peptide, reaching a maximum (18 µM) at 30 min after ingestion, and decreasing to approximately 20% at 4 h after ingestion. Finally, in cell culture, levels of Pro-Gly in the medium above 0.1 µg/mL significantly enhanced elastin synthesis of normal human dermal fibroblasts (NHDF) without affecting the rate of cell proliferation.

Elastin peptides prepared from piscine and mammalian elastic tissues inhibit collagen-induced platelet aggregation and stimulate migration and proliferation of human skin fibroblasts.

We obtained pure elastin peptides from bovine ligamentum nuchae, porcine aorta, and bonito bulbus arteriosus. The inhibitory activity of these elastin peptides on platelet aggregation induced by collagen and the migratory and proliferative responsivenesses of human skin fibroblasts to these elastin peptides were examined. All of bonito, bovine, and porcine elastin peptides found to inhibit platelet aggregation, but bonito elastin peptides showed a higher inhibitory activity than bovine and porcine elastin peptides did. All elastin peptides enhanced the proliferation of fibroblasts 3.5- to 4.5-fold at a concentration of 10 µg/ml. Bovine and porcine elastin peptides stimulated the migration of fibroblasts, with the optimal response occurring at 10(-1) µg/ml, while maximal response was at 10(2) µg/ml for bonito elastin peptides. Furthermore, pretreatment of fibroblasts by lactose depressed their ability to migrate in response to all elastin peptides, suggesting the involvement of elastin receptor in cell response. These results suggest that both mammalian and piscine elastin peptides can be applied as useful biomaterials in which elasticity, antithrombotic property, and the enhancement of cell migration and proliferation are required.