In Vitro and In Vivo Biocompatibility Studies of a Cast and Coated Titanium Alloy.

Ursula Sommer,Christian Heiss,Katharina Viehoff,Volker Alt,Reinhard Schnettler,Ulrich Thormann,Lucie De Azevedo,Stephan Laurich,Sabine Wenisch

doi:10.3390/molecules25153399

Abstract

The biocompatibility of a cast porous and with a calcium titanate reaction layer functionalized titanium alloy (Ti-6Al-7Nb) was tested by means of cell culture, and a small (rat) and large animal (sheep) model. The uncoated titanium material served as a control. In-vitro tests included the validation of osteoblast-like cells attached to the surface of the material with scanning electron microscopy and immunofluorescence of cytoskeletal actin as well as their osteogenic development, the ability to mineralize, and their vitality. Following the in-vitro tests a small animal (rat) and big animal (sheep) model were accomplished by inserting a cylindrical titanium implant into a drill hole defect in the femoral condyle. After 7, 14, and 30 days (rat) and 6 months (sheep) the condyles were studied regarding histological and histomorphometrical characteristics. Uncoated and coated material showed a good biocompatibility both in cell culture and animal models. While the defect area in the rat is well consolidated after 30 days, the sheep show only little bone inside the implant after 6 months, possibly due to stress shielding. None of the executed methods indicated a statistically significant difference between coated and uncoated material.

Highlights

The ability to regenerate is the outstanding property of the bone tissue in the difference to all other tissues [1]
The osteogenically differentiated cells are able to adhere to the metal surface and build a dense cell carpet, regardless of whether the titanium alloy is coated or uncoated, as can be seen in scanning electron microscopic (SEM, Figure 1) and immunofluorescence microscopic (IF, Figure 2) examinations
In the area of interest (AOI), the bone area over tissue area (BA/TA) of both Calcein- (e) and Alizarin (f)-labeled bone shows no significant differences between coated and uncoated samples

Summary

Introduction

The ability to regenerate is the outstanding property of the bone tissue in the difference to all other tissues [1]. The regenerative reconstitution of bones does not occur, if a defect exceeds a critical size or the distance between the ends of a fracture is too large. The healing processes of iatrogenic bone defects, which can occur after tumor or cyst resection, require a surgical treatment by filling in the defects. This applies to bony defects, which arise in the course of post-traumatic healing complications and infections [3]. Only autologous bone met these requirements and is still considered the gold standard for defect filling. The use of autologous bone has disadvantages.

Methods

Results

Conclusion