Embryonic stem (ES) cells have significant potential in tissue engineering and regenerative medicine due to their ability to generate any type of cell or tissue in the body. The review covers the history of murine and human ES cell lines, including the practical and ethical aspects of ES cell isolation, maintenance, and differentiation. Murine ES cells were first isolated in 1981, and human ES cells were derived in 1998, marking a major breakthrough for developmental biology and regenerative medicine. ES cells can be propagated indefinitely in vitro and are capable of differentiating into all mature somatic cell types when induced by appropriate signals. The review discusses the challenges and advancements in ES cell technology, such as the development of therapies for human disease, the need for efficient purification methods, and the potential for immunogenicity issues. Despite these challenges, ES cells show promise for revolutionizing the treatment of human diseases, with potential applications in organ repair and replacement. However, clinical trials are still in their early stages, and many technical and ethical hurdles must be overcome before large-scale applications can be realized.Embryonic stem (ES) cells have significant potential in tissue engineering and regenerative medicine due to their ability to generate any type of cell or tissue in the body. The review covers the history of murine and human ES cell lines, including the practical and ethical aspects of ES cell isolation, maintenance, and differentiation. Murine ES cells were first isolated in 1981, and human ES cells were derived in 1998, marking a major breakthrough for developmental biology and regenerative medicine. ES cells can be propagated indefinitely in vitro and are capable of differentiating into all mature somatic cell types when induced by appropriate signals. The review discusses the challenges and advancements in ES cell technology, such as the development of therapies for human disease, the need for efficient purification methods, and the potential for immunogenicity issues. Despite these challenges, ES cells show promise for revolutionizing the treatment of human diseases, with potential applications in organ repair and replacement. However, clinical trials are still in their early stages, and many technical and ethical hurdles must be overcome before large-scale applications can be realized.