Abstract: The invention relates to tissue regeneration and repair by cell transplant. More particularly, the invention concerns a method for preparing adult stem cells which preserves the diversity and plasticity of said cells. The invention also concerns the use of said stem cells obtained by the inventive extraction method for therapeutic uses, including gene and cell therapy. The inventive preparation method essentially consists in: cell extraction, mechanical dissociation, enzymatic dissociation, maintaining the cells obtained in a specific culture medium enabling preservation of diversity and plasticity, said method excluding cell culture.