Australian researchers at the University of New South Wales have demonstrated that stem cells from a person's own eyes can be cultured and reapplied to the same person's eyes with a contact lens.  This then allows the eye to regenerate its cornea, thus curing a form of blindness caused by damage or defect there.  (Normally the eye cannot regenerate its cornea.)  Link

Stem cells are the progenitor cells of all specialized cells.  There are many kinds of stem cells, the most well-known being "embryonic" stem cells.  Embryonic stem cells are able to generate any bodily cells, but adult stem cells can only regenerate the cells of the organ they originate in.

Most embryonic stem cell research had been banned in the United States.  On March 9, 2009, President Obama removed the restrictions on federal funding for research involving new lines of human embryonic stem cells. Prior to that, federal funding was limited to research of adult stem cells and embryonic stem cell lines in existence prior to August 9, 2001 and kept alive since then.