The man behind bioactive glass for wound healing

Bone
iStock/Ericlefrancais

SciTech Europa Quarterly speaks to Prof Aldo Boccaccini – the man behind the research study trying to understand how the bioactive glass can promote wound healing

Bioactive glasses: from bone regeneration to wound healing

Originally biomaterials were used to replace diseased or damaged tissues. First generation biomaterials were selected to be as bio-inert as possible and thereby minimise interactions at the interface with host tissues. Bioactive glasses (BGs) were discovered in 1969 and provided the interfacial bonding of an implant with host tissues as an alternative to eliminate the formation of scar tissue.1

BGs can be used as a material that forms a direct bond to bone. As a result, BGs are being increasingly considered in the tissue engineering field, being investigated not only in bone tissue engineering but also in soft tissue regeneration approaches.2 BGs are able to enhance vascularization via the action of ionic dissolution products (biologically active ions), and therefore, are able to play a part in soft tissue repair (such as wound healing).

Meet Professor Aldo R Boccaccini – professor of Biomaterials and Head of the Institute of Biomaterials at the Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Germany. Boccaccini’s main research area is the use of glasses, ceramics and polymer/glass composites for biomedical, functional, and structural applications.

SciTech Europa Quarterly speaks with Boccaccini to talk about his current project ‘Bioactive glasses: from bone regeneration to wound healing’, and how BGs are breaking into the world of wound healing.

What are BGs? Why are they important, and how are they used?

BGs are a family of inorganic materials based on silicate, phosphate and borate compositions.  Most extensively investigated BGs are in the silicate system, especially as bone substituting materials and in bone tissue engineering. On the other hand borate BGs are being increasingly  considered in wound healing applications. BGs are important because they were the first man made material that was shown to connect/bond directly to bone. Originally bioactive glass was developed as a substitute material for bone; a material that would create a very strong link/bond with bone tissue, and therefore would be used as an alternative to other materials, for example in bone replacement devices, dental applications, small bone implants and coatings.

Later on research found that when BGs were in contact with bodily fluids, they would release particular ions, dissolution as products, and these ions released from the bio glass are also active and interact with the cells – they are biologically active ions. This is also really important because you don’t only have this initial effect of direct bonding with bone tissue, but you also have direct biological effects on cells induced by the release of specific concentrations of these metallic ions from the glass.

Can you explain the work and role of the project ‘BGs: from bone regeneration to wound healing’? What has been found?

Originally, the interest in BGs stemmed from their use as a substitute material (for example in bone replacement devices, bone filling materials or dental applications). This interest then started to go towards tissue regeneration and soft-tissue engineering, where these glasses are being proposed in particular applications related to a variety of tissues in the human body. One of which is wound healing.

The research here is trying to understand how the BGs can promote the healing of wounds and burns. For example, one particular case is difficult-to-heal wounds such as diabetic wounds – people who suffer diabetes can develop incurable wounds in their legs, in some cases such chronic wounds are so tragic, for example due to high risk of infections, that the leg must be amputated. BGs in different shapes, for example fibers or particulate in composites, can be positively used to heal these wounds, especially by using the release of ions which will have an angiogenic and anti-bacterial effect. Some products based on BGs for wound healing are already available. The glasses can be also designed to release specific ions that kill bacteria, and as a result, stop the spread of infections in the site of the wound.

What we are doing in our research projects, for example, is adding bioactive glass particles into polymeric fibres (which we fabricate through electrospinning), and these composite fibres will act as a flexible, porous, wound-dressing material that can be effective in the treatment of chronic wounds by releasing biologically active ions in controlled temporal and spatial manner from the BG particles during the degradation of the fibers.

What would you say have been some of the main challenges so far? How have these been overcome?

In general, the challenge is to be able to characterise the effect of BGs in relevant in vivo situations (in a real body environment). However, many research studies have focused on in vitro (cell biology) studies (outside if the body). One challenge would therefore be to expand the number of in vivo studies, both in bone regeneration, and soft tissue regeneration and wound healing. To overcome this challenge, it would require us to better understand the behaviour of the material during the time of implantation into the in vivo environment on a well-designed animal model.

What is next for this project? What would you say/hope is the future of BGs?

Within this project, we are continuing to enhance the capability of these materials by investigating the effects of different chemical compositions. Our work and the work of numerous research groups worldwide investigating BGs is contributing to develop a library of chemical compositions of different BGs, and we are particularly interested in understanding what is the combined or synergistic effect of different ions, in different concentrations, on different types of cells relevant to the mechanisms of tissue regeneration and wound healing. We think that by increasing the complexity of the chemical composition of the glasses, by adding different ions that are going to be released under different time-dependent concentration ratios, we will be able to provide better or more effective healing effects.

The future and the hope of BGs in my opinion, is that they become materials of choice to tackle many of the current unmet medical needs, for example, in the areas of chronic wound healing, antibiotic-free treatment of bone infections and even in some cases, in terms of treating cancer. This is because it has been previously shown that BGs of specific morphologies (for example nanoparticles or mesoporous structures) can act as drug carriers and could be designed to synergistically connect the direct and controlled delivery of drugs for cancer treatment with, for example, the effect of biologically active ions released from the carrier (bioactive glass).

Aldo R Boccaccini

Head of the Institute of Biomaterials

Department of Materials Science and Engineering

University of Erlangen-Nuremberg

+49 91318528601

aldo.boccaccini@fau.de

www.biomat.techfak.uni-erlangen.org/

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