The promise of tissue engineering in oral and craniofacial rehabilitation
In dentistry there is a real clinical need for more effective ways to treat congenital growth defects, facial reconstruction following disease or trauma, and the costs and complications associated with orofacial infection and inflammation.
Drs Omar Abubaker (SoD), Lynne Elmore (SoM) Gary Bowlin (SoE) and Parthasarthy Madurantakam (SoD) started proceedings with their perspectives on clinical need and research in the area of tissue engineering in oral and craniofacial rehabilitation with a particular emphasis on bone regeneration. In summary over the past ten years there have been significant improvements in the accuracy of modeling facial constructs through the advent of digital scanning but there is still real clinical need where defects are too large for conventional bone grafts. The emergence of stem cells derived from oro-facial tissue combined with advances in implant materials provide a near term opportunity to develop better treatment for patients.
This was followed by an open floor discussion which encompassed current research and possible areas for collaborative research.
There was general agreement over many of the areas that require work to deliver patient benefit and an agreement that both scientists and clinicians need to be equally engaged – the clinicians to identify the need, the engineers and scientists to solve the problems working with the clinicians to make sure these solutions can be implemented. It became clear during the course of the conversation that the use of stem cells with tissue engineering is not a distant hope but a much closer realty with bone marrow derived stem cells already in clinical trials for bone formation.
Stem cells in bone generation.
The school of medicine has expertise in isolating mesenchymal stem cells from a wide range of tissues more recently working with the school of dentistry on isolation of stem cells from gingival tissues. Indeed dentists have a number of sources of stem cells – pulp, gingiva and wisdom teeth that can be accessed during routine dental operations that could be convenient sources for stem cells required for oro facial diseases.
However, there do appear to be differences in stem cells isolated from these different tissues with third molar stem cells in particular showing different growth parameters.
In addition most of the work done to date has been with stem cells isolated from younger healthier patients but differences in stem cell characteristics are also dependent on the age and health of the individual from which they are extracted. This makes it hard to draw general conclusions for clinical treatment. As greater need for treatment will be from older less healthy patients it will become important to understand how characteristics of these cells and any differences in their ability to generate bone.
Materials and stem cell differentiation
Research in the school of engineering is determining the best scaffolds for the regeneration of bone. This encompasses both the type of material used e.g. titanium, how the implants are made e.g. laser sintering, 3D printing and how to change the surface to optimize the growth and differentiation of the stem cells. Although much promise is being held for 3D printing at the moment the resolution is not sufficiently good to enable optimization of implant surfaces.
The retention of stem cells at the required site is critical as they can easily migrate following transplantation. By altering the altering the surface of implants better retention of stem cells at the site where they are required is possible.
The growth factor gradient that stem cells are exposed to affects their differentiation. Inappropriate differentiation and local complications can arise from either too much or too little growth factor. The timing of the stem cells exposure to growth factor is also critical. In the school of engineering two approaches to this problem are being explored. One employs the use of novel delivery agents allowing slow release of the growth factors while the alternative approach is to engineer implant surfaces to encourage the cells themselves to secret sufficient growth factors for bone regeneration thus avoiding the need for exogenous growth factors.
Other topics that were touched on but time prevented exploring further
Inflammation
How tissue engineering can reduce inflammation from implantation thus giving the implant a better chance of being accepted and retained.
Bone glue
How can we develop bone glue that can withstand the maxillary forces?
Morphology of teeth
To get stem cell to grow new teeth we really need to work with developmental biologist to understand the underlying molecular mechanisms of tooth morphology.
This group will form the core of an interest group on tissue engineering and plan to meet on a regular basis to dicuss research and discoveries with a view to developing collaborations. For further information or to join this group please contact sodresearch@vcu.edu
Categories Research