Augmentation of blood platelet levels by intratracheal administration of an adenovirus vector encoding human thrombopoietin cDNA.

This study was designed to evaluate the hypothesis that administration of a replication-deficient, recombinant adenovirus vector to the epithelial surface of the respiratory tract can be used to deliver a recombinant protein to the systemic circulation in sufficient quantities to evoke a systemic response appropriate to the recombinant protein. We administered AdCMV.TPO-an adenovirus vector containing an expression cassette coding for the human thrombopoietin (TPO) cDNA-to the respiratory epithelium of immunocompetent Balb/c mice. Over the following week, serum human TPO levels were elevated, platelet levels increased more than sixfold, and megakaryocytosis was evident in bone marrow. This strategy may be a useful approach to the nonparenteral administration of a variety of therapeutic recombinant proteins, such as those relevant to clotting, endocrine function, and bone-marrow function.