Tetraethylenepentamine (TEPA) is a low-molecular-weight linear polyamine exerting metal-chelating properties. TEPA is widely used in industrial applications. The principal hazards that arise in working with TEPA are those associated with similar organic amines; namely, a corrosive action on skin and eyes. TEPA biological activity was attributed to its effect on cellular Cu levels as (a) treatment with TEPA resulted in reduction of cellular Cu, and (b) excess of Cu reversed TEPA's activity and accelerated differentiation. TEPA was shown to attenuate the differentiation of ex vivo cultured hematopoietic cells resulting in preferential expansion of early progenitors. A phase I/II trial was performed to test the feasibility and safety of transplantation of CD133+ cord blood (CB) hematopoietic progenitors cultured in media containing stem cell factor, FLT-3 ligand, interleukin-6, thrombopoietin and TEPA. Transplanting a population of CD133+ CB cells which were expanded ex vivo for 21 days using SCF, FLT3, IL-6, TPO and the copper chelator TEPA (StemEx) was feasible. The expanded cells were well tolerated, with no infusion-related adverse events observed.