Progress in human embryonic stem cell research in the United States between 2001 and 2010

Abstract

On August 9th, 2001, the federal government of the United States announced a policy restricting federal funds available for research on human embryonic stem cell (hESCs) out of concern for the "vast ethical mine fields" associated with the creation of embryos for research purposes. Until the policy was repealed on March 9th, 2009, no U.S. federal funds were available for research on hESCs extracted after August 9, 2001, and only limited federal funds were available for research on a subset of hESC lines that had previously been extracted. This paper analyzes how the 2001 U.S. federal funding restrictions influenced the quantity and geography of peer-reviewed journal publications on hESC. The primary finding is that the 2001 policy did not have a significant aggregate effect on hESC research in the U.S. After a brief lag in early 2000s, U.S. hESC research maintained pace with other areas of stem cell and genetic research. The policy had several other consequences. First, it was tied to increased hESC research funding within the U.S. at the state level, leading to concentration of related activities in a relatively small number of states. Second, it stimulated increased collaborative research between US-based scientists and those in countries with flexible policies toward hESC research (including Canada, the U.K., Israel, China, Spain, and South Korea). Third, it encouraged independent hESC research in countries without restrictions.

Fig 1. Number of Publications of hESC, Other SC, and RNAi Research by Country of Authorship.

The lines in the figures report the number of publications by scholars based in the U.S. and in countries with either constrained or flexible policies regarding hESC research; publications with authors from more than one country are credited to each country. The vertical axis reports the number of publications. The percentages in parentheses denote the share of total publications during the period (the shares sum to slightly less than 100% because they do not include publications from countries with no specified hESC policies: for hESC, this amounts to the exclusion of 15 publications from scholars in seven countries). The difference in the share of hESC publications from flexible versus constrained countries is significantly greater than the differences for other SC and RNAi (p<0.05).

Fig 2. hESC Publication Trends in U.S. States With and Without Funding, 1999–2011.

The vertical axis in the figure reports the number of publications per year in three classes of states: States in which funding for hESC research began in 2005–2006 (green line), those in which funding began in 2007–2008 (blue line), and those that never funded hESC research (red line).

Fig 3. U.S.-only Publications and U.S.-Cross-Border Collaborations.

The figure reports the share of publications by U.S.-based scientists that involved only U.S.-based researchers and those with co-authors based in other countries. The categories include historical patterns for SC before the U.S. federal funding limits (1980–2001), as well as for SC (other than hESC), RNAi, and hESC after the funding limits (2002–2010).