The embodiments disclosed herein relate to the construction of fully-deleted Adenovirus-based gene delivery vectors packaged without helper Adenovirus, and more particularly to their use in gene therapy for gene and protein expression, vaccine development, and immunosuppressive therapy for allogeneic transplantation. In an embodiment, a method for propagating an adenoviral vector includes (a) providing an Adenovirus packaging cell line; (b) transfecting a fully-deleted Adenoviral vector construct into the cell line; and optionally (c) transfecting a packaging construct into the cell line, wherein the fully-deleted Adenoviral vector construct and optionally the packaging construct can transfect the Adenovirus packaging cell line resulting in the encapsidation of a fully-deleted Adenoviral vector independent of helper Adenovirus. In an embodiment, a target cell is transduced with the encapsidated fully-deleted Adenoviral vector for treating a condition, disease or a disorder.