Harnessing advancements in biodegradable polymers has made tissue engineering an increasingly viable alternative, offering the benefits of established approaches whilst minimising their drawbacks. Whilst the choice of material, indication for use and ideal reconstruction are for debate, a reproducible method of assessment is required to allow for optimisation of pre-clinical technology as well as safely assess in-vivo performance of tissue engineered constructs. A multi-modal method for assessment is presented, incorporating clinical radiographic techniques and histopathological analysis.
Traditional CT and MRI were used both in vivo and on explanted specimens from pigs implanted with a medical grade polycaprolactone scaffold 1 year after implantation. Following sacrifice histomorphometric assessment with haematoxylin and eosin, and Masson’s trichrome staining were performed. Immunohistochemistry stains for adipose tissue (Perilipin 1), vasculature (von Willebrand Factor) and macrophage activity (CD68, CD206, iNOS) were also done.
Morphology assessment with CT and MRI was well correlated with histological findings in terms of tissue composition – demonstrating a balance of viable adipose tissue with supporting fibrous tissue adjacent to scaffold architecture. Of particular interest, both radiographic and histological assessment demonstrated no signs of capsule formation. Immunohistochemistry showed a predominance of M1 macrophage activity adjacent to scaffold struts, whilst well-vascularised adipose tissue was demonstrated throughout the analysed specimen.
The ability to correlate cost-effective radiographic methods of analysis with established histological techniques provides an opportunity to both understand the underlying physiology and regenerative pathways as well as clinically monitor tissue growth in a tissue-engineered construct