Recent progressions in stem cell research: breakthroughs achieved and challenges faced.

Stem cell studies have been conducted to study characteristics of stem cells, to develop better techniques for patient-specific stem cell lines generation, and to explore the therapeutic potential of stem cells. Techniques that enable efficient generation of new stem cell lines would facilitate research and allow generation of patient-specific stem cell lines for transplantation therapy. Somatic-Cell Nuclear Transfer (SCNT), which involves injection of donor cell nucleus into enucleated ovum, is the standard technique for new embryonic stem (ES) cell lines generation; presently its efficiency is low. A newer technique, pluripotent stem cell induction, reprograms somatic cells into induced pluripotent stem (iPS) cells by introducing certain factors into somatic cells. While certain adult stem cell treatments have been investigated on human participants, most ES cell or iPS cell treatments were still experimented on animal models. Recently, therapeutic potential of stem cell for several disorders was demonstrated. Researchers demonstrated stem cell's potential for treating hematologic disorders by correcting sickle cell anemia in rat model with iPS cells. Its potential role in treating cardiovascular disorder was demonstrated as injection of damaged rat heart with human ES cells derived cardiomyocyte plus "prosurvival" cocktail improved heart function. It might also treat nervous system disorders; injected into brain, ES cells derived neurons replace some loss cells in stroke rats and iPS cells derived neurons improved Parkinsonian syndrome in rats. Progress was also seen in other aspects of regenerative medicine. To overcome controversies caused by embryo destruction for obtaining ES cells, single blastomer stem cell derivation, Cdx2-inactivation, and parthenogenesis were proposed. All ES cell, iPS cell, and adult stem cell research should be continued with support from all sides.