The present invention provides a system for delivering a time-varying stimulation field to a subject. In the system, a power source, a control component and a transmission component operate as a stimulation field generator to provide a predetermined time-varying stimulation field to up-regulate or down-regulate an expression level of human genes. The present invention also provides a wearable apparatus for delivering the time-varying magnetic field to mammalian cells associated with bone formation in a subject. The wearable apparatus contains the stimulation field generator in a housing. The resulted modification on gene regulation of these genes and mammalian cells promotes the retention, repair of and reduction of compromised mammalian cartilage, bone, and associated tissue.
