Anionic Polymers for Implantation

Abstract

Synthetic polymers are more and more frequently used in clinical medicine for the reconstruction of seriously damaged tissues and organs. Unfortunately, they are recognized by immune cells. This process includes the adsorption of bioactive proteins such as fibronectin, vitronectin, complement, fibrinogen or immunoglobulins on foreign surfaces and their recognition by receptors on immune cells.' This usually influences the activity and phenotypic characteristics of immune cells colonizing the implant.Numerous data from the area of anti-infectious immunity demonstrated the distinct effect of chemistry of the surface of bacterial cells on their recognition by non-specific immunity. Bacteria containing the anionic sialic acids in both, monomeric and polymeric form are known as poor activators of the alternative complement pathway, which is also of a great importance in the non-self recognition of synthetic materials2 Sialic acids are a quite wide family of derivatives of Nacetylneuraminic acid, which are characterized by the presence of carboxylate anions and are normally expressed on the surface of cells in vertebrates. This monosaccharide is recognized by specific populations of macrophages in lymphatic nodes and in the spleen by endogenous lectin sialoadhesin which is participating in immune cell maturation in lymphoid organs.' However, the knowledge about the sialoadhesin expression in inflammatory macrophages is only minimal.In this study we demonstrate the N-acetylneuraminic acid (Neu)-binding sites in inflammatory macrophages colonizing the surface of implants in the rat, to estimate the binding capacity of macrophages for this anionic monosaccharide with described biomimetic properties.The effect of carboxylate anions on hydrogel supports or implants on monocyte adhesion in vitro and macrophage adhesion and fusion on surfaces of strips subcutaneously implanted into the rat was tested for a better understanding of the effect of this anion on the non-self recognition of synthetic hydrogels. An intraperitoneal injection of beads prepared from the same polymers was used for the phenotypic characterization of red pulp spleen macrophages and so for an estimation for any "This research was supported by grant No 304/93/0666 of the Grant Agency of the Czech Republic.Tel: +420 2 24 91 50 03; Fax: +420 2 29 76 92.Tel: +420 2 36 03 41; Fax: +420 2 36 79 81. 95

Enhancing the biological activity of immobilized osteopontin using a type‐1 collagen affinity coating

“…2 Thus poly(HEMA) provides a low-fouling background in which to conjugate and investigate specific proteins of interest. Osteopontin (OPN) is an extracellular matrix protein known to regulate inflammatory responses such as macrophage recruitment, phagocytosis, and wound remodeling.…”

“…Poly(2-hydroxyethyl methacrylate) (poly(HEMA)), a highly hydrated polymer with free hydroxyl groups, possesses the inherent ability to resist rapid protein adsorption 1 and cell adhesion. 2 Thus poly(HEMA) provides a low-fouling background in which to conjugate and investigate specific proteins of interest. Osteopontin (OPN) is an extracellular matrix protein known to regulate inflammatory responses such as macrophage recruitment, phagocytosis, and wound remodeling.…”

“…Poly(2‐hydroxyethyl methacrylate) (poly(HEMA)), a highly hydrated polymer with free hydroxyl groups, possesses the inherent ability to resist rapid protein adsorption1 and cell adhesion 2. Thus poly(HEMA) provides a low‐fouling background in which to conjugate and investigate specific proteins of interest.…”

Tissue Interaction with Biomaterials

“…The cell attachment to the implant follows two main strategies for the cell-material interactions: one is by creating an inert surface that inhibits the cell attachment and proliferation, and the other is by creating a surface that promotes them. The implants constructed to fulfill the former criterion are used in the joint prostheses (as heads and cups) [1], blood-contacting devices (heart valves), smooth bioinert vascular prostheses, vesicles for drug delivery or catheters for hemodialysis [1][2][3][4][5] or intraocular lenses [6,7]. Those in the latter case are used in bone implants for the formation of osseous tissue [8][9][10] or skin substitutes made up of polymeric sheet with a feeder layer of fibroblasts that is covered by keratinocytes [11].…”