Analysis of Osteoclastogenesis/Osteoblastogenesis Using Human Bone Marrow Derived Co-Cultures on Nanotopographical Titania Surfaces

Background: Aseptic loosening remains the primary reason for failure of orthopaedic implants. Therefore a prime focus of Orthopaedic research is to improve osteointegration and outcomes of joint replacements. The topography of a material surface has been shown to alter cell adhesion, proliferation and growth. The use of nanotopography to promote cell adhesion and bone formation is hoped to improve osteointegration and outcomes of implants. We have previously shown that 15nm high features are bioactive. The arrangement of nanofeatures has been shown to be of importance and block-copolymer separation allows nanopillars to be anodised into the titania layer, providing a compromise of control of order and height of nanopillars. Osteoblast/osteoclast stem cell co-cultures are believed to give the most accurate representation of the in vivo environment, allowing assessment of bone remodelling related to biomaterials. Aims: To assess the use of nanotopography on titania substrates when cultured in a human bone marrow derived co-culture method. Hypothesis: Under co-culture conditions 15nm high nanopillars on titania substrate will induce significantly increased levels of osteogenic differentiation, producing a method of enhancing secondary implant fixation. Methods/Design: Bone marrow was aspirated from patients undergoing elective arthroplasty. Co-culture of adherent osteoprogenitors and osteoclast progenitors on polished titania and titania patterned with 15nm nanopillars fabricated by the block copolymer technique was performed. Histochemical staining has been performed to identify and quantify osteoclasts and bone nodule formation. Scanning electron microscopy (SEM) has been conducted to morphologically examine the effect on differentiation of untreated and nanopatterned titania substrates on osteoprogenitors and osteoclasts. Real-Time, quantitative reverse-transcription polymerase chain reaction is currently being utilised to quantify expression of osteoblast, osteoclast and inflammatory response related genes. Results: SEM has shown an increase in bone deposition on titania substrates with 15nm nanopillars. The remaining results of this project will be presented with a discussion of their clinical significance