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Galactosyl-knock-out engineered pig as a xenogenic donor source of adipose MSCs for bone regeneration

Schubert, Thomas, Poilvache, Hervé, Galli, Cesare, Gianello, Pierre, Dufrane, Denis
Biomaterials 2013 v.34 no.13 pp. 3279-3289
animal models, antibodies, bone substitutes, enzyme-linked immunosorbent assay, epitopes, humans, immunoglobulin G, immunohistochemistry, immunomodulation, macrophages, phenotype, rats, stem cells, swine
Pig adipose mesenchymal stem cells (AMSCs) could be proposed for the improvement of bone substitute. However, these xenogenic cells retain a galactosyl (Gal) epitope that elicits xenorejection. Our work aims to use Gal-Knock-Out (Gal-KO) pig AMSCs to associate cellular immunomodulation, humoral down-elicitation of Gal-KO cells and osteogenic capacity of AMSCs. Human and pig AMSCs were compared for proliferation/differentiation kinetics and bone neoformation in vivo. Humoral reaction against pig Gal+ vs. Gal-KO AMSCs and immunomodulation properties of Gal+ vs. Gal-KO AMSCs were assessed in vitro. Humoral/cellular reactions against Gal+ vs. Gal-KO osteogenic differentiated pig AMSC xenografts were assessed in an immunocompetent rodent model. Expansion/differentiation/bone neoformation was significantly improved with differentiated pig AMSCs compared with human cells. Based on immunohistochemistry and cell-based ELISA, Gal+ AMSCs had higher sensitivity to preformed/induced anti-pig antibodies than Gal-KO AMSCs. In vitro cellular immunomodulation was similar between Gal+ and Gal-KO AMSCs. In vivo, a significant reduction of anti-pig IgG was found at 1 month in rats implanted with Gal-KO AMSCs compared with those implanted with Gal+ AMSCs. Lymphocyte/macrophage infiltration of osteogenic differentiated pig AMSC xenografts was significantly lower at post-operative day (POD) 7 in recipients of Gal-KO vs. Gal+ pig cells. No significant difference was found at POD 28. The combination of the cellular immunomodulation with the Gal-KO phenotype of AMSCs can significantly improve the cellular engraftment of pig osteogenic cells by delaying xenorejection.