<p>A bioreactor, kit, a method of using the device to promoting growing and /or culture of a cell, and a method for regenerating and/or improving the function of mammalian cells. The bioreactor includes a controlling circuit coupled to magnetic field emitter that emits relatively steep and short-lived magnetic field pulses during these an active ephemeral period. The bioreactor also provides a relatively long-term inactive phase in which no magnetic field pulses are imposed. The kit includes the unassembled components of the bioreactor. The method of using the bioreactor and of regenerating and/or improving the function of mammalian cells includes the step of applying a time variant magnetic field through the cell to promote growing and/or culturing, and then introducing the cells to a mammal to regenerate cells.</p>