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08 December 2009 NANO Magazine - Issue 5

Nanomedicine

Image Credit: NANO Magazine.

In this article, Richard Moore argues that the application of nanotechnology to medicine may result in more that just improvements to materials, diagnosis and treatments. It could carry the potential to completely change how we look at medicine, disease and wellbeing. Medicine is going through a period of great change. Not only is the science of medicine constantly evolving but our understanding of what a “disease” is and patients’ perceptions and expectations of what medicine can and should deliver is continually changing. The latest impact on this evolving scenario is the application of nanotechnology to the practice of medicine, and it is likely that this new technology will affect our understanding of medicine in radically new ways.

As the knowledge of the biological basis of diseases improves, as patients become more informed and as lifestyles change our interpretation and perception of what a disease is evolves. A couple of hundred years ago surgery would have seemed miraculous and diseases like smallpox and polio, which are now all but eradicated in the West, were ubiquitous. With a knowledge of the human genome and of the underlying basis of disease, there is a tendency in Western society to seek to eradicate any perceived medical imperfection and even a desire by some to actually “engineer” their children so as to avoid certain diseases or conditions. What would not have been considered a commonplace health issue in the past is now actively treated or prevented and “lifestyle” conditions like obesity rather than acute life-threatening diseases have become more of a daily concern.

Nanomedicine pioneer Robert Freitas Jr. proposes a new view of disease, which he terms the “volitional normative” model, as being a more valid approach for the nanomedical era. In this model “normal” is considered optimal functioning according to the patient’s own genetic programming as opposed to “normal” for the wider patient base, and physical condition is considered a volitional state where the patient’s own wishes are crucial as to defining a state of health. This model is at considerable variance to those definitions of health currently applied in society.

Application of this model to current healthcare provision would require a considerable rethink as most of our systems currently work on a generalized approach to health across a population rather than optimizing the state of health of an individual according to their personal genetic and physiological disposition and personal views of what “healthy” means. Nevertheless, the very great impact that nanomedicine is like to bring towards a greater individualization and personalization of treatment means that this is a problem that will have to be faced sooner rather than later.

Some of the impacts of nanomedicine for the patient and medical professional

Because nanomedicine permits a molecular intervention at hitherto impossible physiological and even cellular metabolic levels, it will eventually become possible to develop therapies based on the patient’s own genotype. Even in the shorter term, highly personalized treatments will be facilitated by nanotechnology. Some examples could include:

Early diagnosis of disease and real-time monitoring of the patient’s condition

A major research area for nanomedicine is in the areas of in vitro and in vivo diagnosis and biosensors. Using a broad definition of “disease”, it will become possible to detect biological changes and disease signs at a very early stage. A great deal of medicine is currently reactive, i.e. the patient is treated only once, signs or symptoms become apparent and the condition has become established. Although, due to huge advances in medical knowledge and technology, diagnosis has become much earlier, it is still often too late either for the patient or leads to large costs on the healthcare provision system.

Lab-on-a-chip (LOC) devices have become familiar in recent years to the general public. Nanotechnology is enabling new generations of LOCs to become highly specific for the detection of viruses, bacteria and a wide range of metabolic functions using tiny quantities of analyte and returning a wide range of results extremely rapidly. New generations of biosensors, likewise, have been developed that are able to detect minute changes in physiological state or the presence of pathological agents down to single molecules or viral/bacterial entities. The combination of both will facilitate the development of new generations of medical devices including very fast and accurate in vitro diagnostics and implantable in vivo diagnostic devices that can operate in real time, perhaps transmitting signals back to other devices like implantable cardiac devices or insulin pumps.

A further impact on early stage diagnosis will be through the rapid development of nanoscale medical imaging agents that will facilitate the much earlier and far more accurate imaging of features as part of a diagnostic or screening regime. Furthermore, imaging may be linked to targeting and/or activation of therapies as part of a so-called “theranostic” approach, i.e. a procedure that combines both diagnosis and therapy.

No two individuals will respond in exactly the same manner to a given drug, and no two disease conditions are exactly the same. It follows then that, ideally, the drug of choice should be matched to both the individual and the condition it is intended to treat. Pharmaceutical science has been in transformation in recent years to meet this challenge and nanotechnology is set to further revolutionize drug design and delivery. Advances in molecular biology and genomics now enable us to far better understand the causes and course of a given condition or disease and nanotechnology is providing the means to be able to design and manufacture substances and materials at a molecular level.

In all therapies, the ability to effectively target the therapeutic agent to the disease site is of paramount importance for a successful outcome. In many cancer treatments, for example, drugs are known to be effective against cancerous cells but are currently limited to being delivered systemically throughout the whole body in a high dose to achieve the necessary therapeutic level at the tumour site with consequent disadvantages and serious side effects for the patient. Much nanomedical research is currently focused on novel means for drug targeting and delivery to enable much smaller and less systemically toxic doses of drug to be delivered precisely to the target site at the required level. Examples of approaches being used include encapsulation of drugs in nanoparticles such as dendrimers, micelles and nanoshells and targeting these by means of a variety of proteins, peptides and other molecular ligands that bind to the target site, e.g. a cancer cell or a specific receptor in the body.

Other types of novel therapeutic approaches that involve nanotechnology include

targeting semi-metallic or metallic nanoparticles, e.g. silica, iron or gold, to tumour sites and then activating them by external means, e.g. light, magnetic field, ultrasound, to produce heat or soft radiation locally that can destroy the cancer cells in situ gene therapy cell therapy Regenerative medicine, including tissue engineering, seeks to restore lost function or damaged tissue by regenerating that tissue, or even whole organs, using human cells, often the patient’s own. It involves a multidisciplinary approach between cell biology, biochemistry and biomaterials engineering. Nanotechnology is being used to produce new generations of biomaterial scaffolds that can encourage or support cell growth and differentiation into often complex tissue types. With gene therapy and cell therapy, regenerative medicine is the subject of new European regulation and will be discussed in detail in future editions of Nano.

From these necessarily brief examples, it can be seen that nanotechnology will impact medical treatment in dramatic ways and will carry the capability of developing new generations of drugs and other therapies that are much more focused on the treatment of the individual rather than a population of patients. In addition, citizens are increasingly taking an active role in maximizing and maintaining their levels of health from a multitude of different starting points. It may be necessary, therefore, from a societal level to reinterpret what we mean by both “medicine” and “disease” towards far broader definitions that take into account these changes in understanding and expectation. In addition, while nanotechnology may be able to offer far better individualized treatments, does the way that healthcare provision operates in most countries, i.e. designed and funded on an “average” patient and diseases profile, need to be radically overhauled to deliver the promise of nanomedicine?

Richard Moore is Manager of Nanomedicine and Life Sciences at the Institute of Nanotechnology.

Source: NANO Magazine - Issue 5 /...

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