Bone-like tissue formation using an equine COLLOSS® E-filled titanium scaffolding material

COLLOSS®, a bovine extracellular matrix product containing native BMPs has already shown osteoinductive properties. To overcome problems with risk of transmissable spongiform encephalopathy (TSE) infection, an equine derived version was investigated in this study, named COLLOSS® E. Disc- and tube-shaped implants were made from titanium fibre mesh. The central space of tubes was filled and the discs were impregnated with the COLLOSS® E material to assess osteo-induction. These implants and non-loaded controls were implanted subcutaneously into the back of Wistar rats. After implantation periods of 2, 8, and 12 weeks, the implants were retrieved and sections were made. Histology showed a thin fibrous capsule surrounding the titanium mesh and a very mild tissue reaction. The disc implants, loaded or non-loaded, showed no bone formation at all. After 2 weeks of implantation 3 out of 5 of the loaded tubes showed bone formation with a mean of 0.3 mm2 areas of new formed bone, after 8 weeks 3 out of 6 and 0.7 mm2, and after 12 weeks this increased to 6 out of 6 and 1.0 mm2. In the non-loaded tubes only connective tissue in growth was seen. In conclusion, it was demonstrated that COLLOSS® E material, loaded in a titanium fibre mesh tube shows osteoinductive properties. The effect of COLLOSS® E has to be investigated further in orthotopic sites, which resemble more the final clinical application for bone reconstruction.