The invention relates to a medical device comprising non-sintered bioactive glass particles or fibres having a diameter in the range 5-100 .mu.m, bioactive glass comprising SiO.sub.2, Na.sub.2O, CaO, K.sub.2O, MgO, B.sub.2O.sub.3 and P.sub.2O.sub.5, wherein the amount of SiO.sub.2 is 50-65 wt-% of the final total weight, Na.sub.2O is 5-26 wt-% of the final total weight, CaO is 10-25 wt-% of the final total weight, K.sub.2O is 0-15 wt-% of the final total weight, MgO is 0-6 wt-% of the final total weight, B.sub.2O.sub.3 is 0-4 wt-% of the final total weight, and P.sub.2O.sub.5 is 0-4 wt-% of the final total weight, provided that the total amount of Na.sub.2O and K.sub.2O is 10-30 wt-% of the final total weight The device is essentially drug free. The invention also relates to the use of said composition for treating lesions associated with compromised or poor vascularisation and for preventing avascular fibrosis.