From stem cells to alien life: The big scientific breakthroughs of 2010

New hope for blocking HIV

A vaccine for HIV remains elusive, but scientists are making progress with other means of preventing infections by the virus that causes AIDS. In a two-year clinical trial, South African women cut their risk of infection in half when they regularly used an inexpensive vaginal gel containing tenofovir, a medication widely used to treat AIDS. It’s the first time a gel containing a microbicide has been found to work against HIV, and its success means that women no longer need to solely rely on men to wear a condom. Meanwhile, another drug commonly used to treat the AIDS virus in infected patients was shown to block infection altogether in sexually active gay men if taken daily. Three-quarters of subjects remained uninfected after a year if they regularly took the AIDS drug Truvada. The results “represent a major advance in HIV-prevention research,” says Kevin Fenton, a physician with the Centers for Disease Control and Prevention. “For the first time, we have evidence that a daily pill used to treat HIV is partially effective for preventing HIV.”

A breast cancer vaccine?

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Breast cancer kills 40,000 American women annually, but new hope is on the horizon: Scientists have developed a vaccine that blocks the formation of breast tumors in mice and may open the door to routine immunization for women. Previous research has identified a protein, called alpha-lactalbumin, common to many breast-cancer cells; the protein isn’t found in normal breast cells except when women are breast-feeding. Researchers at the Cleveland Clinic developed a vaccine that targets the protein without harming healthy tissue; none of the mice injected with the vaccine developed breast cancer, while all the others did. “If it works in humans the way it works in mice, this will be monumental,” says immunologist and study author Vincent Tuohy. “We could eliminate breast cancer.”

Stem-cell therapy used in paralyzed patient

Stem cells may one day provide a cure for many diseases, and this year, they were used for the first time in a clinical trial on humans. Surgeons injected millions of embryonic stem cells into a recently paralyzed patient, in hopes that they will grow into spinal sheath cells and repair communication along the spinal cord. It’s only the first phase of the trial, aimed mainly at testing the treatment’s safety. But it’s “a major morale boost for scientists, clinicians, and most of all patients,” says regenerative-medicine expert Chris Mason. After years of controversy and speculation, Mason says, stem-cell therapy is being transformed “from a scientific curiosity into advanced health care.”

Life takes on a new form

There’s now alien life on Earth. It didn’t arrive via a spaceship, but through an experiment in which NASA astrobiologists “taught” bacteria to live without phosphorous. Phosphorus was considered one of the elements necessary for life’s biochemistry, along with carbon, hydrogen, nitrogen, oxygen, and sulfur. But scientists took bacteria that had been growing in the arsenic-rich mud of California’s Mono Lake and let them reproduce in mud that contained ever-decreasing concentrations of phosphorus. Over just a few months, the bacteria learned to replace the phosphorous in their tiny bodies with arsenic; even their DNA contained the element. These bacteria thus became a life-form never before seen on this planet. The finding, says NASA’s Pamela Conrad, suggests that life could evolve elsewhere in the universe under a much broader range of conditions than was previously thought. “This will fundamentally change our definition of life and how we look for it,” says Conrad.