“…This is not only because of the multilineage progenitor potential of MSCs, but also because of their capacity to modulate the host microenvironment by secreting a variety of factors, such as cytokines, chemokines or growth factors, which can mediate diverse functions via crosstalk between different cell types (Friedenstein et al, ; Doorn et al, ; Murphy et al, ). Examples of using sheep as a model system include spinal fusion (Goldschlager et al, ), segmental tibial defects (Niemeyer et al, ), chondral/osteochondral repair (Ahern et al, ; Caminal et al, ,b, ; Vives et al, ), tendon and ligament regeneration (Lacitignola et al, ) and osteonecrosis of the femoral head (Velez et al, ), among others.…”