Experimental setup. In total 12 athymic nude mice ranging from six to eight weeks of age were used for this study (a). According to the seeding and culture conditions, 4 groups were built: 1. blank scaffolds, 2. seeded with hMSCs, 3. seeded with osteogenically stimulated hMSCs, 4. seeded with osteogenically stimulated hMSCs and treated with VEGF. After 2 and 12 weeks, scaffolds were harvested including the surrounding tissue. One scaffold of each group was split into two parts (b): one half was destined for decalcification the other for un-decalcified histological examination. The other scaffold of each group was shock frozen in fluid nitrogen and stored at -80°C until use for molecular analysis (b).