The present invention provides novel compositions and methods for pharmaceutical or nutraceutical use in an animal, preferably in a human. In one aspect, compositions and methods are provided for promoting cell growth, tissue repair and organ regeneration, preferably in vivo and in situ. The composition comprises a sterol compound dissolved in oil at a concentration at least 0.5% by weight. The compositions may be used in the treatment of various conditions caused by injury, diseases and aging. As shown clinically, the methodology disclosed in the present invention was used successfully to regenerate or clone a new organ through cultivation of regenerative stem cells in vivo and in situ.