Governing stem cells: regenerative medicine in Europe - the vision and recommendations from the EUCelLEX project by Bell, J, Bordag, N, Borry, P, Bovenberg, J, Dagher, G, Grewal, J, Hoppe, N, Isasi, R, Kaye, J, Knoppers, B, Kwisda, K, Morrison, M, Neron, A, Nys, H, Oberauner-Wappis, L, Rial-Sebbag, E, Sandor, J, Shabani, M, Tournay, V, Varju, M, Zatloukal, K