Human therapeutic cloning, pitfalls and lack luster because of rapid developments in induced pluripotent stem cell technology

Abstract

Background: Therapeutic cloning is the combination of somatic cell nuclear transfer (SCNT) and embryonic stem cell (ES) techniques to create specific ES cells that match those of a patient. Because ES cells derived by nuclear transfer (SCNT ES cells) are genetically identical to the donor, it will not generate rejection by the host's immune system and thus therapeutically may be more acceptable. Induced pluripotent stem cells (iPS) are a type of pluripotent stem cell artificially derived from an adult somatic cell by inducing a forced expression of a set of specific pluripotent genes. In the past few years, rapid progress in reprogramming and iPS technology has been made, and it seems to shadow any progress made in SCNT programs. Objective: This review compares the application perspective of SCNT with that of iPS in regenerative medicine. Methods: We conducted a literature search using the MEDLINE (PubMed), Wiley InterScience, Springer, EBSCO, and Annual Reviews databases using the keywords "iPS", "ES", "SCNT" "induced pluripotent stem cells", "embryonic stem cells", "therapeutic cloning", "regenerative medicine", and "somatic cell nuclear transfer". Only articles published in English were included in this review. Results: These two methods both have advantages and disadvantages. Nevertheless, by using SCNT to generate patient-specific cell lines, it eliminates complications by avoiding the use of viral vectors during iPS generation. Success in in vitro matured eggs from aged women and even differentiation of oocytes from germ stem cells will further enhance the application of SCNT in regenerative medicine. Conclusion: Human SCNT may be an appropriate mean of generating patient stem cell lines for clinical therapy in the near future.