IMPROVING THE OOKP

The osteo-odonto-keratoprosthesis (OOKP) is associated with the greatest long-term anatomical and functional success among the different approaches available. However, like all keratoprostheses, the OOKP has limitations. In particular, the complexity of the multi-staged surgery, its cost, and the need for harvesting tooth and bone are major obstacles to its more widespread use. 
Speaking at the 5th EuCornea Congress in London, UK, Ganesh C Ingavle PhD discussed work under way at the University of Brighton to develop a polymeric OOKP skirt using interpenetrating network (IPN) hydrogels. Dr Ingavle is Marie Curie Experienced Researcher, School of Pharmacy and Biomolecular Sciences, University of Brighton, UK. 
A synthetic OOKP skirt would overcome these drawbacks and offer other advantages as well, including the potential for replacement if needed and for enhancing the optical cylinder design. With those issues in mind, various groups have been working to develop a synthetic analogue substitute for the dental lamina in the OOKP.

Basic requirements
Dr Ingavle said that to be successful, a synthetic OOKP skirt should mimic the alveo-dental tissue in porosity, bone-like mineral composition by encapsulating nano-hydroxyapatite coated polymer microspheres, mechanical strength, biostability and the ability to support cell integration and migration.
Considering these attributes, hydrogels are an attractive material because of their excellent biocompatibility and high permeability. In addition, hydrogels are amenable to surface modification and can be formed into any desirable shape. However, hydrogels suffer from having low mechanical strength and they provide relatively low support for cell adhesion.
Use of the IPN approach overcomes those limitations, said Dr Ingavle. He explained that an IPN is a combination of two networks that are independent of each other, but physically interlocked. The main advantage of the IPN is that it provides a mechanism for modifying the properties of the hydrogel to achieve those that are desired.
“A combination of biological and synthetic polymers can result in a material with dramatically improved characteristics,” reported Dr Ingavle.
He demonstrated this feature by reviewing results from laboratory studies looking at different iterations of IPN hydrogels, and showing how the physical and biological properties of the IPN hydrogel can be controlled by manipulating the composition. 
The studies have included experiments evaluating the materials’ swelling properties, mechanical properties, and the migration, adhesion, proliferation, and viability of keratocytes and fibroblasts. 

Ganesh C Ingavle: G.C.Ingavle@brighton.ac.uk