Abstract
Aim
To compare a variety of commercially available bone graft substitutes (BGS) in terms of promoting adherence, proliferation and differentiation of osteoprogenitor cells.
Materials and methods
A fixed number of porcine mononuclear cells obtained from cancellous bone of the proximal femur was mixed with a standard volume of BGS and then cultured for one week in media followed by two weeks in osteogenic media. BGS included commercially available β-Tricalcium Phosphate (□-TCP), highly porous β-TCP, Hydroxyapatite/Tricalcium phosphate composite, calcium sulphate (CS), Hydroxyapatite (HA), Demineralised bone matrix (DBM), polygraft, and polymers (PGA, PLGA).
Staining for live/dead cells as well as scanning electron microscopy (SEM) were carried out on all samples to determine viability and cellular binding. Further outcome measures included alkaline phosphatase assays with normalisation for DNA content to quantify osteogenic potential. Negative (BGS without cells) and positive (culture expanded osteoprogenitors) control experiments were carried out in parallel to validate the results.
Results
Live/dead and SEM imaging showed higher cellular viability and attachment with β-TCP than with other BGS. In the experimental setup the average alkaline phosphatase activity in nmol/ml (normalised value for DNA content in nmol/μg DNA) per sample was 657.58 (132.03) for β-TCP, 36.22 (unable to normalise) for calcium sulphate, 19.93 (11.39) for the HA/ TCP composite, 14.79 (18.53) for polygraft, 13.98 (8.15) for the highly porous β-TCP, 5.56 (10.0) for PLGA, 3.82 (3.8) and for HA. It was not possible to analyse data for either DBM or PGA.
Conclusion
Under theses experimental conditions, β-TCP has apparent favourable characteristics in terms of maintaining viability of osteoprogenitor cells and allowing proliferation and differentiation. Further work will be carried out to characterise the effect that BGS have on osteoprogenitor cells.
