Characterization and differentiation potential of rabbit mesenchymal stem cells for translational regenerative medicine

Mesenchymal stem cells (MSCs) derived from the adult bone marrow are multipotent stem cells that can give rise to lineages of bone, cartilage, muscle, fat, and others. The rabbit is a common preclinical model used for cardiovascular and orthopaedic applications. MSCs derived from the rabbit whole bone marrow are routinely investigated in these models for regenerative medicine applications. However, rabbit MSCs (rbMSCs) have not been extensively characterized in terms of immunophenotypic characteristics and differentiation potential and more specifically, in comparison to human MSCs (hMSCs). This study examined rbMSCs' surface antigens as well as their multipotent differentiation potential. In addition, the transduction efficiency of rbMSCs using a lentiviral vector with red fluorescent protein (RFP) as a method for labeling the cells for in vitro and in vivo use was also examined. RbMSCs were positive for CD44 and CD29 and negative for CD45 and CD14, which is similar to hMSCs, but rbMSCs did not express CD90. RbMSCs also expressed the pluripotent transcription factor, Sox2. The rbMSCs at early passages differentiated along the osteoblastic, chondrocytic, and adipocytic lineages. However, quantitative analyses demonstrated lower levels of differentiation markers for rabbit cells as compared to human cells. Transduction efficiency of 90.5% was observed for rbMSC transfected with RFP. Transduced cells also retained their osteogenic potential, but proliferation was reduced in comparison to nontransduced cells. This study demonstrates that MSCs isolated from the rabbit bone marrow have differences from human cells and should be considered when using rbMSCs in preclinical models for MSC regenerative medicine or tissue engineering strategies.