The pace of progress in stem-cell research seems to be quickening, and the field’s future looks promising. Last week, a team at the Harvard Stem Cell Institute found what looks like a revolutionary way to create stem cells that could be safe enough to use as treatments in humans.

Let’s recap a few major developments to date. At first, ethical concerns hampered progress in stem-cell research when the best way to obtain the cells was to harvest them from discarded embryos. After scientists learned how to create induced pluripotent stem (iPS) cells by deprogramming adult cells, these ethical concerns were rendered moot.

The deprogramming method itself raised problems, however, because it permanently integrated genes with the potential to induce cancer into adult cells to transform them into iPS cells. The resulting stem cells had the potential to cause tumors and were thus not considered safe for use in human patients.

Then, in May 2009, researchers in Wisconsin described a method for creating iPS cells with nonintegrating episomal vectors. In contrast with the previous inducement method, the episomes in this process are lost during cell division, thus leaving the resulting iPS cells free of potentially problematic foreign genes. It therefore became possible to use the same tools in a different way to create iPS cells that were safer than before.

Things changed once again last week when a team at the Harvard Stem Cell Institute found a small molecule that could replace at least one of the cancer-related genes in the inducement process. Like the Wisconsin researchers’ method, the new technique created stem cells that are safer than was previously possible.

These efforts represents various routes toward the goal of creating personalized cells that are safe enough to be the basis of cell-based therapies. The researchers hope that a chemical-based (rather than gene-based) process for creating stem cells would yield therapies that require no immunosuppressive drugs.

These exciting reports have ramifications for research, personalized medicine, and the development of effective new biological drugs. During a challenging time for the drug industry, advances such as these offer hope for the future.