Loadable, ultra-porous permanent scaffolds for bone tissue engineering

In bone tissue engineering, scaffold materials may be used to repair and rebuild diseased bones.

Scaffolds are used for many types of procedures in oro-maxillofacial and orthopedic surgery that require bones to heal, e.g. bone loss caused by trauma, tumors and bone resorption due to inflammation. The three-dimensional properties of these materials play a vital role to guide new bone regeneration and subsequent successful integration of the scaffolding material in the host tissue.

The two main reasons to apply bone scaffolds are to provide an environment for bone healing and at the same time give mechanical support to the skeleton during the healing process. To date, the dominant alternative for autologous bone grafting has been the use of donated allogenic bone. Harvesting tissue from donor source imposes the risk of transmitting infectious diseases and causing immunogenic responses.

Besides, allogenic bone tissues undergoes a rigorous washing process that removes all of the living tissue to eliminate or greatly reduce this risk, but also significantly decreases the osteogenic properties of this bone. There has also been an increasing shortage of supply for allogenic bone. Therefore there is a steady rising demand for synthetic scaffold materials for bone engineering.

A variety of bone scaffolds from natural and synthetic materials have been developed. Titanium oxide (TiO₂) was chosen as scaffold material in the present project since this material has proven to fulfill many of the demands for a bone scaffold material. One of the major obstacles with synthetic osteogenic scaffolds is their lack of mechanical strength to carry load after insertion into the adult body, and so far this has also been the case for TiO₂ based scaffold materials However, we have showed that it is possible to produce mechanical loadable ceramics based on TiO₂ and that these materials are suitable for use for bone engineering. The scaffolds produced in this project combine porosity as high as 85% with a compressive strength of 2.5 MPa, similar to the strength of healthy trabecular bone.

These ultra-porous TiO₂ scaffolds are found to be biocompatible in in vitro studies and cells growing in these structures show a lower general cytotoxicity and higher proliferation rate than other scaffolds on the market. It has also been shown that these ultra-porous TiO₂ scaffolds has higher porosity, surface-to-volume ratio and pore interconnectivity than commercial scaffolds available in the clinic today (BoneCeramic and BioOss®). The TiO₂ scaffolds have also been tested for its in vivo performance in rabbits and pigs with promising results The current project is funded by a EU Eureka-Eurostars grant.