Fibroblast Growth Factor Activity
Fibroblast growth factor (FGF) signaling is involved in a wide range of important biological activities with differential effects in various cell types. The activity of FGF is modulated by glycosaminoglycans, found both in the extracellular matrix and on the cell surface. They affect FGF signaling by interacting with both the growth factor and the FGF receptor.
These molecules are critical in wound healing as such dynamic process is interactive and depends on proper regulation of fibroblasts. Without regulation excessive scarring results as a feature of impaired healing (keloid and hypertrophic scars), a serious health problem that most of the time affects people's quality of life for the treatment cost of such lesions is high, and often, the results are unsatisfactory.
Fibroblast: a type of cell that synthesizes collagens, glycosaminoglycans, reticular and elastic fibers, and glycoproteins found in the extracellular matrix. In growing individuals fibroblasts are dividing and synthesizing ground substances.
The Helix Aspersa Müller Glycoconjugates Have Fibroblast Growth Factor Activity:
Facilitates the migration of keratinocytes, thus helping to repair wounds
Induces significant fibroblast proliferation
Enhances fibroblast functional capability, thus improving fibroplasias
Induces synthesis of new collagen
Provides hyaluronic acid (essential in all repair process)
The glycoconjugates help achieve the correct balance between the synthesis and degradation of important structural elements such as collagen and elastin
Collagenase: Enzymes that catalyze the hydrolysis of collagen and gelatin.
Gelatinase activity: A protease that begins the hydrolytic breakdown of proteins usually by splitting them into polypeptide chains. They are involved in early tissue repair and in prolonged tissue remodeling. Various types of matrix metalloproteinases (collagenase and gelatinase enzymes) are selectively expressed or activated at the various periods of wound healing and determine the presence or absence of abnormal scars: keloids or hypertrophic scars.
The matrix metalloproteinases (MMP) are a group of zinc-dependent enzymes , which degrade varying components of the extracellular skin matrix in both normal and diseased tissue. Skin matrix is a framework that holds the skin together and consists mainly of intermeshed polymers such as collagen and elastin. The skin matrix is responsible for the skin's mechanical properties, including firmness, strength, suppleness, and elasticity. The weaker and less regular the matrix, the more wrinkles, roughness, and sag one tends to have. Whenever skin is damaged, malformed or worn out, skin matrix is broken down by the MMP enzymes and then is synthesized by the fibroblasts. Therefore, MMP enzymes play a critical role in skin physiology.
The latest approach in skin care is to maintain a healthy balance of these enzymes.
In healthy, youthful skin, the synthesis and degradation of the matrix are in balance; damaged or redundant matrix is degraded while the deficit is replenished by the ongoing synthesis. Unfortunately, this intricate balance gets disrupted with age; too little of the matrix is synthesized and too much is degraded. MMP levels rise excessively with age. Research indicates that reversal of MMP levels to normal youthful levels in aged individuals is an effective method to remove the damaged matrix and preserve the healthy one. For this purpose, the utilization of MMP inhibitors in the form of drugs, cosmetic formulations, and lifestyle changes is the new cosmetic find.
Function of fibroblasts
The main function of fibroblasts is to maintain the structural integrity of connective tissue by continuously secreting precursors of the extracellular matrix. Fibroblasts secrete the precursors of all the components of the extracellular matrix, primarily the ground complex and a variety of fibers. The composition of the extracellular matrix determines the physical properties of connective tissues. Proteoglycans (proteins bound to glycosaminoglycans or glycoproteins) bind multiple components of the extracellular matrix by serving as important regulators of cell behavior. Tissue damage stimulates fibrocytes and induces migration and readily proliferation of fibroblasts in multiple stages of tissue repair including wound contraction. Fibroblasts can give rise to other cells, such as bone cells, fat cells, and smooth muscle cells. All those are cells of mesodermal origin, which means a layer from which the organs and tissues of the body develop through further differentiation.
Growth factors are polypeptides (proteins) that bind to receptors on the cell surface, with the primary result of activating cellular proliferation and/or differentiation. Many growth factors are quite versatile, stimulating cellular division in numerous different cell types; while others are specific to a particular cell-type. There are at least 21 distinct members of the FGF family of growth factors.
Fibroblast growth factors act specifically on various types of epithelial cells including keratinocytes of the skin, intestinal epithelial cells and hepatocytes. In addition, some types of Fibroblast Growth Factor have been shown to be more than growth factors: they can protect epithelial cells from damaging effects induced, for example, by radiation and oxidative stress. Therefore, they are currently in clinical trials for the treatment of oral mucositis, a severe side-effect of cancer therapy characterized by painful inflammation and ulceration of the oral epithelium. Reference: “Fibroblast growth factors in epithelial repair and cytoprotection”. Susanne Braun, Ulrich auf dem Keller, Heike Steiling and Sabine Werner Institute of Cell Biology, Department of Biology, ETH Zurich, Honggerberg, CH-8093 Zurich, Switzerland. April 2004.
Cartoon to illustrate the functions of FGFs in a healing skin wound. Upon lesions, dermal fibroblasts (violet) and __ T cells (red) secrete FGF-7 and FGF-10; suprabasal keratinocytes (green) express FGF-22. In a paracrine (blue and red arrows) or autocrine manner (green arrow), respectively, they activate keratinocytes at the wound edge and stimulate reepithelialization. In addition, they induce the expression of cytoprotective genes in keratinocytes, including the gene that encodes the Nrf2 transcription factor. Nrf2 then regulates the expression of proteins involved in the detoxification of ROS (Reactive Oxygen Species). The latter are produced in large amounts by neutrophils and macrophages as a defense against invading bacteria.
