Biocompatibility

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IUPAC definition

Biocompatibility (biomedical therapy): Ability of a material to perform with an appropriate host response in a specific application. [1] [lower-alpha 1]

Contents

Biocompatibility: Ability to be in contact with a living system without producing an adverse effect. [1]

Annualpublbiocompatibility19702007.jpg

Biocompatibility is related to the behavior of biomaterials in various contexts. The term refers to the ability of a material to perform with an appropriate host response in a specific situation. [2] The ambiguity of the term reflects the ongoing development of insights into how biomaterials interact with the human body and eventually how those interactions determine the clinical success of a medical device (such as pacemaker, hip replacement or stent). Modern medical devices and prostheses are often made of more than one material so it might not always be sufficient to talk about the biocompatibility of a specific material. [3]

Since the immune response and repair functions in the body are so complicated it is not adequate to describe the biocompatibility of a single material in relation to a single cell type or tissue. Sometimes one hears of biocompatibility testing that is a large battery of in vitro test [4] that is used in accordance with ISO 10993 (or other similar standards) to determine if a certain material (or rather biomedical product) is biocompatible. These tests do not determine the biocompatibility of a material, [5] but they constitute an important step towards the animal testing and finally clinical trials that will determine the biocompatibility of the material in a given application, and thus medical devices such as implants or drug delivery devices. [6] Research results have concluded that during performing in vitro cytotoxicity testing of biomaterials, "the authors should carefully specify the conditions of the test and comparison of different studies should be carried out with caution". [7]

History

The word biocompatibility seems to have been mentioned for the first time in peer-review journals and meetings in 1970 by RJ Hegyeli (Amer Chem Soc Annual Meeting abstract) and CA Homsy. [8] It took almost two decades before it began to be commonly used in scientific literature (see the graph below).

Recently Williams (again) has been trying to reevaluate the current knowledge status regarding what factors determine clinical success. Doing so notes that an implant may not always have to be positively bioactive but it must not do any harm (either locally or systemically). [9]

Five definitions of biocompatibility

  1. "The quality of not having toxic or injurious effects on biological systems". [10]
  2. "The ability of a material to perform with an appropriate host response in a specific application", Williams' definition. [11]
  3. "Comparison of the tissue response produced through the close association of the implanted candidate material to its implant site within the host animal to that tissue response recognised and established as suitable with control materials" - ASTM
  4. "Refers to the ability of a biomaterial to perform its desired function with respect to a medical therapy, without eliciting any undesirable local or systemic effects in the recipient or beneficiary of that therapy, but generating the most appropriate beneficial cellular or tissue response in that specific situation, and optimising the clinically relevant performance of that therapy". [9]
  5. "Biocompatibility is the capability of a prosthesis implanted in the body to exist in harmony with tissue without causing deleterious changes". [12]

Comments on the above five definitions

  1. The Dorland Medical definition not recommended according to Williams Dictionary since it only defines biocompatibility as the absence of host response and does not include any desired or positive interactions between the host tissue and the biomaterials.
  2. This is also called the “Williams definition” or “William's definition”. [13] It was defined in the European Society for Biomaterials Consensus Conference I and can more easily be found in ‘The Williams Dictionary of Biomaterials’.
  3. The ASTM is not recommended according to Williams Dictionary since it only refers to local tissue responses, in animal models.
  4. The fourth is an expansion or rather more precise version of the first definition noting both that low toxicity and the one should be aware of the different demands between various medical applications of the same material.

All these definitions deal with materials and not with devices. This is a drawback since many medical devices are made of more than one material. Much of the pre-clinical testing of the materials is not conducted on the devices but rather the material itself. But at some stage the testing will have to include the device since the shape, geometry and surface treatment etc. of the device will also affect its biocompatibility.

‘Biocompatible’

In the literature, one quite often stumbles upon the adjective form, ‘biocompatible’. However, according to Williams’ definition, this does not make any sense because biocompatibility is contextual, i.e. much more than just the material itself will determine the clinical outcome of the medical device of which the biomaterial is a part. This also points to one of the weaknesses with the current definition because a medical device usually is made of more than one material.

Metallic glasses based on magnesium with zinc and calcium addition are tested as the potential biocompatible metallic biomaterials for biodegradable medical implants [14]

Biocompatibility (or tissue compatibility) describes the ability of a material to perform with an appropriate host response when applied as intended. A biocompatible material may not be completely "inert"; in fact, the appropriateness of the host response is decisive. [15]

Suggested sub-definitions

The scope of the first definition is so wide that D Williams tried to find suitable subgroups of applications in order to be able to make more narrow definitions. In the MDT article from 2003 the chosen supgroups and their definitions were:

Biocompatibility of long-term implanted devices
The biocompatibility of a long-term implantable medical device refers to the ability of the device to perform its intended function, with the desired degree of incorporation in the host, without eliciting any undesirable local or systemic effects in that host.
Biocompatibility of short-term implantable devices
The biocompatibility of a medical device that is intentionally placed within the cardiovascular system for transient diagnostic or therapeutic purposes refers to the ability of the device to carry out its intended function within flowing blood, with minimal interaction between device and blood that adversely affects device performance, and without inducing uncontrolled activation of cellular or plasma protein cascades.
Biocompatibility of tissue-engineering products
The biocompatibility of a scaffold or matrix for a tissue-engineering products refers to the ability to perform as a substrate that will support the appropriate cellular activity, including the facilitation of molecular and mechanical signalling systems, in order to optimise tissue regeneration, without eliciting any undesirable effects in those cells, or inducing any undesirable local or systemic responses in the eventual host.

In these definitions the notion of biocompatibility is related to devices rather than to materials as compared to top three definitions. There was a consensus conference on biomaterial definitions in Sorrento September 15–16, 2005. [16]

See also

Related Research Articles

<span class="mw-page-title-main">Implant (medicine)</span> Device surgically placed within the body for medical purposes

An implant is a medical device manufactured to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure. For example, an implant may be a rod, used to strengthen weak bones. Medical implants are human-made devices, in contrast to a transplant, which is a transplanted biomedical tissue. The surface of implants that contact the body might be made of a biomedical material such as titanium, silicone, or apatite depending on what is the most functional. In 2018, for example, American Elements developed a nickel alloy powder for 3D printing robust, long-lasting, and biocompatible medical implants. In some cases implants contain electronics, e.g. artificial pacemaker and cochlear implants. Some implants are bioactive, such as subcutaneous drug delivery devices in the form of implantable pills or drug-eluting stents.

The ISO 10993 set entails a series of standards for evaluating the biocompatibility of medical devices to manage biological risk. These documents were preceded by the Tripartite agreement and is a part of the international harmonisation of the safe use evaluation of medical devices. For the purpose of the ISO 10993 family of standards, biocompatibility is defined as the "ability of a medical device or material to perform with an appropriate host response in a specific application".

<span class="mw-page-title-main">Bioactive glass</span> Surface reactive glass-ceramic biomaterial

Bioactive glasses are a group of surface reactive glass-ceramic biomaterials and include the original bioactive glass, Bioglass. The biocompatibility and bioactivity of these glasses has led them to be used as implant devices in the human body to repair and replace diseased or damaged bones. Most bioactive glasses are silicate-based glasses that are degradable in body fluids and can act as a vehicle for delivering ions beneficial for healing. Bioactive glass is differentiated from other synthetic bone grafting biomaterials, in that it is the only one with anti-infective and angiogenic properties.

<span class="mw-page-title-main">PLGA</span> Copolymer of varying ratios of polylactic acid and polyglycolic acid

PLGA, PLG, or poly(lactic-co-glycolic) acid is a copolymer which is used in a host of Food and Drug Administration (FDA) approved therapeutic devices, owing to its biodegradability and biocompatibility. PLGA is synthesized by means of ring-opening co-polymerization of two different monomers, the cyclic dimers (1,4-dioxane-2,5-diones) of glycolic acid and lactic acid. Polymers can be synthesized as either random or block copolymers thereby imparting additional polymer properties. Common catalysts used in the preparation of this polymer include tin(II) 2-ethylhexanoate, tin(II) alkoxides, or aluminum isopropoxide. During polymerization, successive monomeric units are linked together in PLGA by ester linkages, thus yielding a linear, aliphatic polyester as a product.

<span class="mw-page-title-main">Organ printing</span> Method of creating artificial organs

Organ printing utilizes techniques similar to conventional 3D printing where a computer model is fed into a printer that lays down successive layers of plastics or wax until a 3D object is produced. In the case of organ printing, the material being used by the printer is a biocompatible plastic. The biocompatible plastic forms a scaffold that acts as the skeleton for the organ that is being printed. As the plastic is being laid down, it is also seeded with human cells from the patient's organ that is being printed for. After printing, the organ is transferred to an incubation chamber to give the cells time to grow. After a sufficient amount of time, the organ is implanted into the patient.

<span class="mw-page-title-main">Biomaterial</span> Any substance that has been engineered to interact with biological systems for a medical purpose

A biomaterial is a substance that has been engineered to interact with biological systems for a medical purpose – either a therapeutic or a diagnostic one. The corresponding field of study, called biomaterials science or biomaterials engineering, is about fifty years old. It has experienced steady growth over its history, with many companies investing large amounts of money into the development of new products. Biomaterials science encompasses elements of medicine, biology, chemistry, tissue engineering and materials science.

<span class="mw-page-title-main">Foreign body reaction</span> Bodily response to the presence of a foreign object

A foreign body reaction (FBR) is a typical tissue response to a foreign body within biological tissue. It usually includes the formation of a foreign body granuloma. Tissue-encapsulation of an implant is an example, as is inflammation around a splinter. Foreign body granuloma formation consists of protein adsorption, macrophages, multinucleated foreign body giant cells, fibroblasts, and angiogenesis. It has also been proposed that the mechanical property of the interface between an implant and its surrounding tissues is critical for the host response.

Nitinol biocompatibility is an important factor in biomedical applications. Nitinol (NiTi), which is formed by alloying nickel and titanium, is a shape-memory alloy with superelastic properties more similar to that of bone, when compared to stainless steel, another commonly used biomaterial. Biomedical applications that utilize nitinol include stents, heart valve tools, bone anchors, staples, septal defect devices and implants. It is a commonly used biomaterial especially in the development of stent technology.

Nano-scaffolding or nanoscaffolding is a medical process used to regrow tissue and bone, including limbs and organs. The nano-scaffold is a three-dimensional structure composed of polymer fibers very small that are scaled from a Nanometer scale. Developed by the American military, the medical technology uses a microscopic apparatus made of fine polymer fibers called a scaffold. Damaged cells grip to the scaffold and begin to rebuild missing bone and tissue through tiny holes in the scaffold. As tissue grows, the scaffold is absorbed into the body and disappears completely.

<span class="mw-page-title-main">Bioceramic</span> Type of ceramic materials that are biocompatible

Bioceramics and bioglasses are ceramic materials that are biocompatible. Bioceramics are an important subset of biomaterials. Bioceramics range in biocompatibility from the ceramic oxides, which are inert in the body, to the other extreme of resorbable materials, which are eventually replaced by the body after they have assisted repair. Bioceramics are used in many types of medical procedures. Bioceramics are typically used as rigid materials in surgical implants, though some bioceramics are flexible. The ceramic materials used are not the same as porcelain type ceramic materials. Rather, bioceramics are closely related to either the body's own materials or are extremely durable metal oxides.

Octacalcium phosphate (sometimes referred to as OCP) is a form of calcium phosphate with formula Ca8H2(PO4)6·5H2O. OCP may be a precursor to tooth enamel, dentine, and bones. OCP is a precursor of hydroxyapatite (HA), an inorganic biomineral that is important in bone growth. OCP has garnered lots of attention due to its inherent biocompatibility. While OCP exhibits good properties in terms of bone growth, very stringent synthesis requirements make it difficult for mass productions, but nevertheless has shown promise not only in-vitro, but also in in-vivo clinical case studies.

<span class="mw-page-title-main">Cell encapsulation</span>

Cell encapsulation is a possible solution to graft rejection in tissue engineering applications. Cell microencapsulation technology involves immobilization of cells within a polymeric semi-permeable membrane. It permits the bidirectional diffusion of molecules such as the influx of oxygen, nutrients, growth factors etc. essential for cell metabolism and the outward diffusion of waste products and therapeutic proteins. At the same time, the semi-permeable nature of the membrane prevents immune cells and antibodies from destroying the encapsulated cells, regarding them as foreign invaders.

<span class="mw-page-title-main">Surface modification of biomaterials with proteins</span>

Biomaterials are materials that are used in contact with biological systems. Biocompatibility and applicability of surface modification with current uses of metallic, polymeric and ceramic biomaterials allow alteration of properties to enhance performance in a biological environment while retaining bulk properties of the desired device.

<span class="mw-page-title-main">Titanium biocompatibility</span>

Titanium was first introduced into surgeries in the 1950s after having been used in dentistry for a decade prior. It is now the metal of choice for prosthetics, internal fixation, inner body devices, and instrumentation. Titanium is used from head to toe in biomedical implants. One can find titanium in neurosurgery, bone conduction hearing aids, false eye implants, spinal fusion cages, pacemakers, toe implants, and shoulder/elbow/hip/knee replacements along with many more. The main reason why titanium is often used in the body is due to titanium's biocompatibility and, with surface modifications, bioactive surface. The surface characteristics that affect biocompatibility are surface texture, steric hindrance, binding sites, and hydrophobicity (wetting). These characteristics are optimized to create an ideal cellular response. Some medical implants, as well as parts of surgical instruments are coated with titanium nitride (TiN).

<span class="mw-page-title-main">Surgical mesh</span> Material used in surgery

Surgical mesh is a medical implant made of loosely woven mesh, which is used in surgery as either a permanent or temporary structural support for organs and other tissues. Surgical mesh can be made from both inorganic and biological materials and is used in a variety of surgeries, although hernia repair is the most common application. It can also be used for reconstructive work, such as in pelvic organ prolapse or to repair physical defects created by extensive resections or traumatic tissue loss.

Bioresorbablemetals are metals or their alloys that degrade safely within the body. The primary metals in this category are magnesium-based and iron-based alloys, although recently zinc has also been investigated. Currently, the primary uses of bioresorbable metals are as stents for blood vessels and other internal ducts.

Materials that are used for biomedical or clinical applications are known as biomaterials. The following article deals with fifth generation biomaterials that are used for bone structure replacement. For any material to be classified for biomedical applications, three requirements must be met. The first requirement is that the material must be biocompatible; it means that the organism should not treat it as a foreign object. Secondly, the material should be biodegradable ; the material should harmlessly degrade or dissolve in the body of the organism to allow it to resume natural functioning. Thirdly, the material should be mechanically sound; for the replacement of load-bearing structures, the material should possess equivalent or greater mechanical stability to ensure high reliability of the graft.

<span class="mw-page-title-main">Surface chemistry of neural implants</span>

As with any material implanted in the body, it is important to minimize or eliminate foreign body response and maximize effectual integration. Neural implants have the potential to increase the quality of life for patients with such disabilities as Alzheimer's, Parkinson's, epilepsy, depression, and migraines. With the complexity of interfaces between a neural implant and brain tissue, adverse reactions such as fibrous tissue encapsulation that hinder the functionality, occur. Surface modifications to these implants can help improve the tissue-implant interface, increasing the lifetime and effectiveness of the implant.

A chronic electrode implant is an electronic device implanted chronically into the brain or other electrically excitable tissue. It may record electrical impulses in the brain or may stimulate neurons with electrical impulses from an external source.

Tissue engineered heart valves (TEHV) offer a new and advancing proposed treatment of creating a living heart valve for people who are in need of either a full or partial heart valve replacement. Currently, there are over a quarter of a million prosthetic heart valves implanted annually, and the number of patients requiring replacement surgeries is only suspected to rise and even triple over the next fifty years. While current treatments offered such as mechanical valves or biological valves are not deleterious to one's health, they both have their own limitations in that mechanical valves necessitate the lifelong use of anticoagulants while biological valves are susceptible to structural degradation and reoperation. Thus, in situ (in its original position or place) tissue engineering of heart valves serves as a novel approach that explores the use creating a living heart valve composed of the host's own cells that is capable of growing, adapting, and interacting within the human body's biological system.

References

Footnotes
  1. ↑ The more general definition could be adopted by the biomedical field. [1]
Notes
  1. 1 2 3 Vert, Michel (2012). "Terminology for biorelated polymers and applications (IUPAC Recommendations 2012)" (PDF). Pure and Applied Chemistry . 84 (2): 377–410. doi:10.1351/PAC-REC-10-12-04. S2CID   98107080. Archived from the original (PDF) on 2015-03-19. Retrieved 2013-07-28.
  2. ↑ "Biological Performance of Materials", Jonathan Black,2006, ISBN   0-8493-3959-6
  3. ↑ Considerations for the Biocompatibility Evaluation of Medical Devices, Kammula and Morris, Medical Device & Diagnostic Industry, May 2001
  4. ↑ “In Vitro Biocompatibility Testing of Biomaterials and Medical Devices” Archived 2015-09-24 at the Wayback Machine , U. Muller, Medical Device Technology, March 2008
  5. ↑ "Biocompatibility Safety Assessment of Medical Devices: FDA/ISO and Japanese Guidelines". Mddionline.com. Archived from the original on 29 November 2014. Retrieved 20 November 2014.
  6. ↑ Reshetov, I. V.; Starceva, O. I.; Istranov, A. L.; Vorona, B. N.; Lyundup, A. V.; Gulyaev, I. V.; Melnikov, D. V.; Shtansky, D. V.; Sheveyko, A. N. (2016). "Three-dimensional biocompatible matrix for reconstructive surgery". AIP Conference Proceedings. 1760 (1): 020056. Bibcode:2016AIPC.1760b0056R. doi:10.1063/1.4960275. ISSN   0094-243X.
  7. ↑ Jablonská, Eva; Kubásek, Jiří; Vojtěch, Dalibor; Ruml, Tomáš; Lipov, Jan (2021-03-23). "Test conditions can significantly affect the results of in vitro cytotoxicity testing of degradable metallic biomaterials". Scientific Reports. 11 (1): 6628. Bibcode:2021NatSR..11.6628J. doi:10.1038/s41598-021-85019-6. ISSN   2045-2322. PMC   7987994 . PMID   33758226.
  8. ↑ Homsy, Charles (1970). "Bio-Compatibility in selection of materials for implantation". Journal of Biomedical Materials Research. 4 (3): 341–356. doi:10.1002/jbm.820040306. PMID   5469182.
  9. 1 2 Williams, David F. (2008). "On the mechanisms of biocompatibility". Biomaterials. 29 (20): 2941–2953. doi:10.1016/j.biomaterials.2008.04.023. PMID   18440630.
  10. ↑ Dorland's Medical Dictionary
  11. ↑ The Williams dictionary of Biomaterials, D.F. Williams, 1999, ISBN   0-85323-921-5
  12. ↑ International dictionary of medicine and biology, E. L. Becker, S. I. Landau, & A. Manuila, 1986, New York: Wiley.
  13. ↑ Williams, D (Oct 2003). "Revisiting the definition of biocompatibility". Medical Device Technology. 14 (8): 10–3. PMID   14603712.
  14. ↑ Nowosielski R., Cesarz-Andraczke K., Sakiewicz P., Maciej A., Jakóbik-Kolon A., Babilas R., Corrosion of biocompatible Mg66+XZn30-XCa4 (X=0.2) bulk metallic glasses, Arch. Metall. Mater. 2016 vol. 61 iss. 2, s. 807-810,
  15. ↑ SCHMALZ, G; ARENHOLT-BINDSLEV, D. Biocompatibility of Dental Materials. Germany: Springer, 2009
  16. ↑ Archived February 6, 2005, at the Wayback Machine
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