In June, the world's first successful transplant of an organ grown from stem cells was performed in Barcelona, Spain. Claudia Castillo (pictured), a 30-year-old mother of two, suffered a damaged windpipe after she contracted tuberculosis. Doctors took a deceased donor's trachea, chemically washed it of original cells and antigens, and seeded the remaining collagen structure with stem cells from Castillo's own bone marrow. The result was a personalized, lab-grown organ that could be transplanted into Castillo's chest without the need for powerful drugs to suppress her immune system. Surgeon Paolo Macchiarini told the BBC the procedure had only been performed on pigs previously.

In August Japanese researchers announced they had created stem-cell lines from a 10-year-old's extracted wisdom teeth. Two months later scientists cultured human stem cells from spermatogonial cells, which normally grow into sperm. The developments suggest that adult stem cells obtained without the creation or destruction of embryos are supplanting the scientific popularity that embryonic stem cells once had.

(Note: This article has been corrected to reflect the proper spelling of surgeon Paolo Macchiarini's name.)