Human embryonic stem cell lines and their use in international research.

Research in human pluripotent stem cells, including human embryonic stem cells (hESC) and human induced pluripotent stem cells (hiPSC), is one of the most dynamic research fields. Despite the high public attention, especially for hESC research, there is only scattered information on the number of hESC lines and the degree, dynamics, and diversification of their use on a global level. In this study we present data on the current number of publicly disclosed hESC lines, on the extent and impact of experimental work involving hESCs, and on the use of specific hESC lines in international research. The results are based on the evaluation of nearly 1,000 research papers published by the end of 2008, which describe experimental work on hESCs, and of a comprehensive database of published hESC lines. The average impact of hESC research papers is high at 7.422, with a predominance of research output by the United States. Of at least 1,071 original hESC lines derived up to November 2009 at 87 institutions in 24 countries, only a fraction is thoroughly characterized. Our data show the global predominance of a few hESC lines in research, but also reveal remarkable country-specific differences. Comparison of hESC and hiPSC application did not show a diminished role for hESC research, but rather revealed that, up to this time, both fields continue to expand, exist independently, and partially overlap.

A psychometric study found AMSTAR 2 to be a valid and moderately reliable appraisal tool.

OBJECTIVES: The objectives of this study were to determine the interrater reliability (IRR) of assessment of multiple systematic reviews (AMSTAR) 2 for reviews of pharmacological or psychological interventions for the treatment of major depression, to compare it to that of AMSTAR and risk of bias in systematic reviews (ROBIS), and to assess the convergent validity between the appraisal tools. STUDY DESIGN AND SETTING: Two groups of four raters were each assigned one of two samples of 30 systematic reviews. All eight raters applied AMSTAR 2 to their sample. Each group also applied either AMSTAR or ROBIS. Fleiss' kappa and Gwet's AC1 were calculated, and agreement between the tools was assessed. RESULTS: The median kappa values as a measure of IRR indicated a moderate agreement for AMSTAR 2 (median = 0.51), a substantial agreement for AMSTAR (median = 0.62), and a fair agreement for ROBIS (median = 0.27). Validity results showed a positive association for AMSTAR and AMSTAR 2 (r = 0.91) as well as ROBIS and AMSTAR 2 (r = 0.84). For the overall rating, AMSTAR 2 showed a high concordance with ROBIS and a lower concordance with AMSTAR. CONCLUSION: The IRR of AMSTAR 2 was found to be slightly lower than the IRR of AMSTAR and higher than the IRR of ROBIS. Validity measurements indicate that AMSTAR 2 is closely related to both ROBIS and AMSTAR.