Abstract
Background A biomaterial serves to support, organize and directly influence the behaviour of growing cells. Chitosan has the capability to be a very useful biomaterial in the speciality of orthopaedics, due to its excellent biocompatibility, and physical properties that allow topographical modification. Chitosan films have potential to be used to coat implant surfaces, regulating bone cells at the implant interface. Enhanced integration may therefore help towards solving problems such as aseptic loosening.
Method 85% deacylated chitosan (Sigma) was dissolved in 2% acetic overnight. The viscous chitosan was then sterilized by autoclaving for 10 minutes. PDMS patterned stamps produced from a silicon mould were added to the viscous chitosan and as the chitosan film forms the topographic impression is left on the surface. The gel was then dried for 36 hours in a sterile system. The pH is neutralized with NaOH1M for 24 hours. The gel was washed in sterile hanks balanced salt solution until the pH was 7.4. Osteoblasts were then grown on these surfaces in a cell culture system and analysed by light microscopy and image analysis.
Results We have successfully designed a protocol for the production of sterile topographically modified chitosan, with surface features that can be produced in the range of 1–100um. We have shown that cells on un-modified chitosan differentiate and form bone at a much slower rate than on chitosan with a modified surface. Findings supported by in-situ alkaline phosphatase levels. Control can be exerted on cell shape and inter-cellular interactions based upon shape and surface area between shapes; with a smaller surface area making adhesion more difficult.
Conclusion. Our data shows that osteoblasts can be controlled by altering chitosans surface topography. Being able to influence biology by changing biomaterial surface features will enhance interaction at the bone implant interface, allowing greater implant integration.
Editoral Secretary Mr Peter Howard. Correspondence should be addressed to BHS at the Royal College of Surgeons, 35 - 43 Lincoln’s Inn Fields, London WC2A 3PN.
