Medical implants of tomorrow may “dialogue” with the human body

Fabio Variola

Fabio Variola envisions novel medical implants capable of promoting bone integration and regeneration.

by Tony Martins
Mindful of our aging population’s increasing reliance on implanted medical devices, Fabio Variola’s nanoengineering research is aimed at modifying the surface of medically relevant metals to enhance bone integration, promote bone formation and provide them with antibacterial and anti-inflammatory capacities.

Works of science fiction abound with imagined biomedical breakthroughs in a quest for eternal life in outer space.
Back here in the practical world, Fabio Variola imagines the same kinds of breakthroughs for our aging population—breakthroughs in the performance of implanted devices based on demonstrable fact, not fiction.

Despite recent advances in medical science, current orthopedic prostheses require replacement every 10 to 15 years. Why? As Variola well knows, the body’s ability to accommodate conventional implants is limited.

“Considering that the human body is likely the best biological system we know, it has the capacity to efficiently adjust itself to new situations,” says Variola, an assistant professor at the University of Ottawa’s Department of Mechanical Engineering.

“Current implants are relatively effective, but they still need significant improvement with respect to their capacity to integrate into tissue. The body readily activates to ensure that the integration occurs, but the final outcome may not be optimal.” 

With a vision not unlike that of a science fiction writer, Variola seeks to endow medically relevant metals with new functionalities that improve the body’s biological response.

“The goal is to create a new generation of implantable materials that can improve the interactions with the human body,” explains Variola, “resulting, for instance, in a faster integration and more stable implants that will last even longer.” 

Variola’s biomedical engineering field takes on an air of wonderment because much of the research focuses on material–bone integration at a level that is almost unimaginably tiny— the nanometric level.

The prefix nano refers to anything with at least one characteristic dimension smaller than 100 nanometres. One nanometre is one billionth of a metre (10-9 m).To give a clearer idea, a strand of human hair is about 100,000 nanometres wide! 

“It is now well established that cellular events like gene and protein expression and cytoskeletal organization are all affected in various ways by nanometric features.” In order to control and guide a specific biological process by physico-chemical cueing, we must be able to precisely design the surface features of implantable materials at the nanoscale.

How might infinitesimal nanostructured materials be of concern to everyday folks? Variola points to a key health concern among the elderly: they lose supporting bone with age.“Therefore, when these individuals need a prosthesis, the surgeon is compelled to implant in a weaker bone, often affected by detrimental conditions,” explains Variola.

“However, wouldn’t it be great if you could take the patient’s own stem cells and guide them to generate bone around the implant? This can be achieved by endowing implantable metals with nanoscale surface features capable of stimulating stem cell proliferation and differentiation. Ultimately, nanoengineered materials will be able to recruit stem cells automatically, without the need for external interventions to bring them to the implantation site.” 

Such a breakthrough may be a ways off, but the nanoporous metal surfaces that Variola has generated during his studies at the Université de Montréal and at the Institut National de la Recherche Scientifique have recently been shown to accelerate stem cell proliferation and possibly to guide the undifferentiated cells to become bone cells. This innovative researcher is now continuing this important work at the University of Ottawa.

Variola’s nanoengineering approach, however, holds promise for additional benefits beyond improved bone integration and regeneration, “such as releasing drugs in a controlled manner directly at the implantation site,” he explains.“Today, the major problem with some drugs is their side effects and lack of specificity.” 

To counter these shortcomings, Variola contends that implantable metals with drug-delivery capacities can optimize drug delivery and localize it where it is needed. This will ultimately result in greater treatment efficiency and in the elimination of side effects related to excessive dosage.

“These materials with drug-delivery capacities can contribute to significantly limiting bacterial infection, inflammation, etc.,” says Variola, “not only in orthopedic applications but also in dental and cardiovascular medicine— fields to be covered in different ways by my present and future research.” 

Taking his vision even further, Variola foresees the biggest leap forward in his field as the development of a material (and thus, an implanted device) “capable not only of providing cues to the surrounding tissues but also of receiving specific biological signals and efficiently responding to them in real time,” he says.“This will be achieved with nanoengineering strategies and will result in the creation of ‘intelligent’ surfaces able to ‘dialogue’ with the surrounding biological environment.” 

If this sounds like the stuff of science fiction, have faith. In just a few short years, Variola may help it become a reality. 

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