Methods of modifying stem cells and compositions of modified stem cells, in particular mesenchymal stem cells, using electric or electromagnetic fields. In various embodiments, the present invention's methods are for the treatment of a human or other mammal subject in need thereof, comprising providing an in vitro culture comprising mesenchymal stem cells, administering an electric stimulation to the in vitro culture, and implanting the mesenchymal stem cells into the subject. Methods also include treatment of a human or other mammal subject, comprising implanting mesenchymal stem cells into the subject, and administering an electric stimulation to the mesenchymal stem cells in situ. Other embodiments include methods of administering electric stimulation in conjunction with growth factors to stem cells.