This invention relates to compositions and methods of delivering therapeutic agents to bone. More specifically, the invention relates to endowing a large molecule vectors i.e., adeno virus, retrovirus, liposomes, micelles, natural and synthetic polymers, or combinations thereof, with the ability to target bone tissue in vivo and with improved stability in the blood, by attaching multiple copies of acid amino acid peptides. One preferred embodiment of the invention relates to endowing an adeno-associated virus (AAV) vector with the ability to target bone-tissue in vivo and improve its stability, by the addition of multiple acidic amino acid peptides attached to the capsid of the viral vector.