Handbook of Biomaterials Biocompatibility

Masoud Mozafari

• Publisher: Woodhead Publishing
• Year: 2020
• Print ISBN: 9780081029671
• eBook ISBN: 9780081029688
• Topic: Technology & Engineering
• Subtopic: Biotechnology in Medicine
• Index: Technology & Engineering

Handbook of Biomaterials Biocompatibility is a systematic reference on host response to different biomaterials, taking into account their physical, mechanical and chemical properties. The book reviews recent progress in the design and study of biomaterials biocompatibility, along with current understanding on how to control immune system response. Sections provide the fundamental theories and challenges of biomaterials biocompatibility, the role of different biomaterials physicochemical surface properties on cell responses, cell responses to different physicochemical properties of polymers, ceramics, metals, carbons and nanomaterials, and biomaterials in different tissues, such as the cardiac, nervous system, cartilage and bone.This resource will be suitable for those working in the fields of materials science, regenerative engineering, medicine, medical devices and nanotechnology.- Reviews the fundamental theories and challenges of biomaterials biocompatibility, including an overview of the standards and regulations- Provides an overview on the cellular and molecular mechanisms involved in host responses to biomaterials- Systematically looks at cellular response and tissue response to a wide range of biomaterials, including polymers, metals, ceramics, alloys and nanomaterials

Section I

An introduction to biocompatibility

Outline

• Chapter 1 Principles of biocompatibility
• Chapter 2 Bacterial cell–biomaterials interactions
• Chapter 3 Macrophage response to biomaterials
• Chapter 4 Dendritic cells responses to biomaterials
• Chapter 5 Impact of biomaterials’ physical properties on cellular and molecular responses
• Chapter 6 Impact of biomaterial mechanics on cellular and molecular responses
• Chapter 7 Cell–biomaterials interactions: the role of growth factors
• Chapter 8 Cell–biomaterial interactions: the role of ligand functionalization
• Chapter 9 On the proliferation of cell proliferation tests
• Chapter 10 In vivo models for biomaterials: applications from cardiovascular tissue engineering
• Chapter 11 Clinical and surgical aspects of medical materials’ biocompatibility
• Chapter 12 Standardization and regulation of biomaterials

Chapter 1

Principles of biocompatibility

Masoud Mozafari, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON, Canada

Abstract

There is a growing interest in the field of biomaterials science and engineering due to its vital effects on human health. There are many factors responsible for the efficacy of biomaterials in contact with living tissues and organs. The biomaterials should be able to demonstrate the ability of implantation in the human body without producing an unacceptable degree of harmful effect on the tissue. This is known by the general term “biocompatibility” which is extensively used by biomaterials scientists. However, there are still some hidden aspects about the mechanisms of biocompatibility.

Keywords

Biomaterials; biocompatibility; toxicity; host response; hemocompatibility; immunocompatibility

1.1 Introduction

There is a growing interest in the field of biomaterials science and engineering due to its vital effects on human health [1]. There are many factors responsible for the efficacy of biomaterials in contact with living tissues and organs [2]. The biomaterials should be able to demonstrate the ability of implantation in the human body without producing an unacceptable degree of harmful effect on the tissue. This is known by the general term “biocompatibility” which is extensively used by biomaterials scientists. However, there is still some hidden aspects about the mechanisms of biocompatibility [3]. The examinations on the first generation of implantable biomaterials indicated that the most efficient biomaterials are those with the minimum chemical reaction in biological environments [4].

Among metallic biomaterials, the plain carbon and vanadium steels were first replaced with stainless steels and further with titanium, platinum, and magnesium alloys, due to their superior advantages in terms of biodegradability and biocompatibility [5]. For polymeric biomaterials, nylons and polyesters were replaced by polytetrafluoroethylene, poly(methyl methacrylate), polyethylene, and silicone, since they are less degradable and toxic. For ceramic-based biomaterials, a range of active glass-ceramics and bioactive glasses have been introduced. This class of biomaterials has attracted great attention due to their ability to incorporate therapeutic ions for the enhancement of biological reactions in the body [6]. In conclusion, biomaterials are usually selected and categorized on the basis that they should not be toxic, immunogenic, thrombogenic, carcinogenic, irritant, and so on, directing us to the definition of biocompatibility [7]. There are a range of material characteristics that greatly influence the host response and further affect the biocompatibility of biomaterials (see Table 1.1) [8]. These characteristics can be divided into two categories related to the bulk and the surface.

Table 1.1

A number of important biomaterial characteristics that can potentially influence the host response.

Bulk material composition

Micro- and nanostructure, morphology, porosity

Crystallinity and crystallography

Water content, hydrophobic–hydrophilic balance

Corrosion parameters and ion release profile

Degradation profile and degradation by-products

Wear debris release profile

Mechanical properties (e.g., stiffness and elastic constants)

SSA

Textural characteristics

Surface chemical composition

Surface molecular mobility

Surface topography

Surface energy

Surface electrical characteristics

SSA, Specific surface area.

Reprinted with permission from Williams DF. On the mechanisms of biocompatibility. Biomaterials 2008;29(20):2941–53.

Based on the type of biomaterial implanted in the body, a number of reactions can happen over time (see Table 1.2) [8]. In most cases, a sequence of events are involved within the interface of the biomaterials and tissues. The overall biocompatibility of biomaterials is related to these interactions. The details of these sequential events have been previously explained in the literature [9].

Table 1.2

The most important host characteristics responses to the implanted biomaterials.

Protein adsorption and desorption

Neutrophil activation

Macrophage activation, foreign body giant cell production, granulation tissue formation

Fibroblast behavior and fibrosis

Microvascular changes

Tissue/organ specific cell responses (e.g., osteoclasts and osteoblasts, endothelial proliferation)

Activation of clotting cascade

Platelet adhesion, activation, aggregation

Complement activation

Antibody production and immune cell responses

Acute hypersensitivity/anaphylaxis

Delayed hypersensitivity

Mutagenic responses, genotoxicity

Reproductive toxicity

Tumor formation

Reprinted with permission from Williams DF. On the mechanisms of biocompatibility. Biomaterials 2008;29(20):2941–53.

The definition of “biomaterial” has been officially introduced about half a century ago as “a nonviable material used in a medical device, intended to interact with biological systems” [10]. More specifically in 1986, a consensus conference on “definitions in biomaterials: proceedings of a consensus conference of the European Society for Biomaterials” was held in Chester, United Kingdom [11]. At that moment, a wide range of biomaterials have been used in medical devices as inert materials. However, by that time, the ability of biomaterials has been greatly changed to interact with living systems in different ways [12].

The field has been further growing because of the need for emerging applications such as applications in advanced delivery systems, imaging techniques, and regenerative medicine. As a result of this transition shift the field needed to redefine the terms and definitions in a more precise way. In a recent conference in Chengdu, China, 2018, a series of biomaterials experts got together to redefine the most important principles of biomaterials and biocompatibility [13]. According to this expert panel, the term “biomaterial” has been defined as “a material designed to take a form that can direct, through interactions with living systems, the course of any therapeutic or diagnostic procedure”.

Among different basic characteristics defined for biomaterials, biocompatibility is of great importance. Biocompatibility can be defined as the ability of a biomaterial with an appropriate host response in a specific application [14–16]. According to this explanation, a biomaterial can interact with biological systems with minimal risk of toxicity and rejection by the immune system.

In the context of host response to biomaterials, carcinogenicity is another important characteristic of an implanted biomaterial, defined as the ability to initiate and/or stimulate the increase of cancerous cells [17].

When a biomaterial is implanted in the body, a series of interactions happen in biological fluids. In most cases, a foreign body capsule is formed on the surface of the biomaterial. This protein layer can greatly change the characteristics of the biomaterial which can further act as a structural and biological barrier between the biomaterial and the tissue [18]. When a biomaterial interacts with blood, a series of even more complex events can happen, where the term hemocompatibility is defined as the compatibility of biomaterials with circulating blood. This interaction should be sustainable without any adverse reactions [19–21]. According to expert opinions, hemocompatibility can be better explained as the ability of a blood-contacting biomaterial to avoid the formation of a t...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of Contributors
• Preface
• Acknowledgments
• Section I: An introduction to biocompatibility
• Section II: Cellular Response to Biomaterials
• Section III: Tissue response to biomaterials
• Index