Blood protein-material interactions

Blood Protein-Material Interactions That Lead to Cellular Adhesion... 

Biomedical Applications Due to their excellent blood compatibility (low interaction with plasma proteins) and high oxygen and moisture permeabilities, siloxane containing copolymers and networks have been extensively evaluated and used in the construction of blood contacting devices and contact lenses 376). Depending on the actual use, the desired mechanical properties of these materials are usually achieved by careful design and selection of the organic component in the copolymers. 

Protein adsorption is the first event that takes place on material surfaces when blood or other body fluids are brought into contact with any material. Therefore, cell - material interactions must be discussed by taking into consideration the species and the nature of the protein adsorbed on the material surfaces. For instance, a series of cell-attachment and spreading experiments [11] of fibroblasts on the surface of modified polystyrene (TCP and Primaria) carried out in the presence of fetal calf serum (FCS) showed that FCS contains components which tend to decrease the attachment and spreading of fibroblast cells. The effect of these nonadhesive components was only evident when the FCS was depleted of vitronectin, showing that vitronectin overcomes the effect of these nonadhesive components and promotes cell-attachment and spreading on the polystyrene surface. Fibronectin, on the other hand, does not play a principal role in this fibroroblast adhesive process (Fig. 2). 

All of this tends to indicate that we may be making a mistake when we look only at the clotting problem resulting from the blood/material interaction. This may merely be a very visible effect of the denaturation of one particular protein in the blood. The solution of the clotting problem may very well only allow us to recognize the fact that other factors are involved and that we have failed to look at the total picture. 

This volume contains manuscripts based on 28 of the 32 contributions presented at the Chicago AIChE Biomaterials Symposium. These manuscripts are organized into three major sections Blood-Materials Interactions, Protein Adsorption on Biomaterials, and New Biomaterials Systems and Applications. Introductory chapters are placed at the beginning of each section of the book to provide nonspecialists with background material and a perspective into these evolving research areas. 

An understanding of protein adsorption behavior is applicable in numerous fields including blood-synthetic materials interfaces, macromolec-ular-rnembrane interactions, receptor interactions, enzyme engineering, adhesion, and protein separation on chromatographic supports. Many methods have evolved to study interfacial adsorption, but no single independent method seems adequate. The ideal technique should produce quantitative, real-time, in situ data concerning the amount, activity, and conformation of proteins adsorbed on well-characterized surfaces. All adsorption techniques are approximations to this optimum. 

Protein Adsorption at the Solid-Solution Interface in Relation to Blood-Material Interactions... 

Clearly studies of single proteins and of mixtures in buffer solutions provide useful information as is evident from the above discussion. However, only studies using blood or plasma can give definitive answers regarding blood material interactions. Accordingly much of our research over the past several years has been devoted to studies of protein adsorption from plasma or blood. 

HE CURRENT STATE OF KNOWLEDGE of proteins at interfaces is reflected in this book. Developed from a symposium that was one of a continuing series entitled Surface Chemistry in Biology, Dentistry, and Medicine, the book is organized around the subtopics of behavior, mechanisms, methods of study, blood-material interactions, and applications of proteins at solid-liquid, air-water, and oil-water interfaces. 

In the present paper, we review the totality of these data and attempt a synthesis of our current knowledge of this system. Such a synthesis relates both to the fundamental aspects of the interaction and to its relationship to blood-material interactions, incorporating both our own work and that of others. In the context of the present Symposiun this paper will serve the additional purpose of Illustrating some of the principles of protein adsorption discussed in the paper of Andrade (this volume). 

In this model, the possible blood-material interactions are as follows the hydrated flexible PEO chain motion suppresses protein adsorption and platelet adhesion, where the PEO chain motion will be increased by the electric repulsion between sulfonate end groups each other. In addition, the sulfonated end groups of PEO chain expel proteins and platelets further by electric repulsion, and moreover the sulfonate groups miglit contribute to better blood compatibility by inhibiting blood coagulation factors. 

While it is convenient to consider blood-material interactions separately from tissue-material interactions, it must be emphasized that blood-material interactions and the inflammatory response are intimately linked and, in fact, early responses to injury involve mainly blood and blood vessels. Therefore, both cellular and humoral elements, i.e., plasma proteins, etc., are considered as cells and components of vascularized connective tissue. 

---