After mining the literature for publications with the phrases iPS cells, induced pluripotent stem cells, induced pluripotent or induced pluripotency in the title, he found a consistent increase in publications each year after the first creation of mouse iPS cells in 2006 by Shinya Yamanaka. That is, a consistent increase until this year, where the first third of the year contained fewer than expected publications. Knoepfler doesn't speculate on what this decrease means-and by the end of the year the discrepancy might disappear.
He did find more diversity in the researchers publishing in the iPS field and in the journals where those papers were published. That makes sense for a field that is becoming ever more mainstream. Knoepfler writes:
I think this is a good thing as the iPS cell field grows. The range of journals publishing iPS cell papers has greatly broadened, which is also a positive for the field as it matures.Knoepfler doesn't speculate on what his findings mean for the field of iPS cells, either as potential therapies or as disease in a dish models. The cells have been the source of much consternation recently as they are shown to differ in significant but clinically unknown ways from embryonic stem cells (as we blogged about here). At the same time, they are also proving their worth in mimicking genetic disease (blogged about here, here, and here).
One discovery that stands out is CIRM's rank as second most prominent funder of iPS papers, following only the NIH. CIRM funds 4.8% of papers that Knoepfler found in his search. Coming in third was the National Natural Science Foundation of China.
CIRM's searchable grants database shows 66 awards to grantees working with iPS cells, worth a total of $146,882,748 or 12% of CIRM funding. You can see those awards here. By contrast, CIRM provides $384,709,412 toward awards working with embryonic stem cells, or 32% of our funding, and $194,221,598 or 16% toward grants working with adult stem cells.
Some CIRM grants fund work using more than one type of stem cell, including several awards to grantees trying to understand differences between iPS and embryonic stem cells.