Study of porcine adipose-derived stem cells for orthopaedic preclinical models

In this study we compare adipose-derived stem cells (ASCs) isolated from pigs and minipigs with human ASC (hASC) considering their use as a promising approach for osteochondral defects treatment to be tested in autologous preclinical model. ASCs, isolated from the interscapular region of both pigs (pASCs) and minipigs (mpASCs) and from patients undergone aesthetic liposuction, have been analysed for their clonogenicity, proliferation, osteogenic and chondrogenic potential. pASCs and mpASCs proliferate faster than human cells with a doubling time of about 66h for pASCs, 57h for mpASCs and 126h for hASCs. Porcine ASCs of both sources are more highly clonogenic with approximately 14% of clogenic cells until the passage 4 compared to human cells (3%). When porcine and human ASCs are induced to osteo-differentiate for 14 days, alkaline phosphatase (ALP) activity is upregulated of about 300% respect to undifferentiated cells; furthermore, an increase in collagene production of approximately 100% is also detected. Moreover, both chondrogenic differentiated pASCs and hASCs, aggregated into micromasses, express an abundant amount of Glycosaminoglycans (GAGs) showing a marked increase in comparison to undifferentiated cells; however, pASCs seem to require a modified differentiative condition since they suffer more than human cells when maintained in pellet culture. To better predict the outcome deriving from the use of porcine ASCs in bone defect models, we assess the osteogenic potential of these cells seeded on different biocompatible biomaterials including nanomodified titanium and collagen-hydroxyapatite composite scaffolds. In particular we observe an increase in ALP levels and collagene production both by undifferentiated and differentiated pASCs, mpASCs and hASCs. A synergistic effect produced by the presence of the scaffolds and the osteogenic stimuli is observed, supporting the possible use of ASCs bioconstructs in some future clinical applications. We conclude that pASCs, mpASCs and hASCs share in vitro some common features and possess a similar osteo-differentiative ability, supporting the idea that the pre-clinical autologous ASCs reimplantation model in pig or minipigs might be predictive of the behaviour of ASCs in future clinical applications of regenerative medicine.