They certainly haven't been sitting still.
Here is a list of research articles the resuscitation research center has recently published, more than 40 this year. One experiment on mild therapeutic hypothermia (no less than 35 degrees C) was conducted in a children's hospital on patients with cardiac arrest, which didn't result in a lower (or higher) mortality rate but showed the treatment was feasible.
There were also experiments on pigs, one of which used hydrogen sulfide as a cooling agent, which didn't have a significant effect. Another one was similar to the experiment in the article, using ice-cold saline aortic flush and chest compressions. This one had a promising outcome: Spontaneous circulation was restored in all eight pigs, and seven of them survived past 9 days. After resuscitation they were only slightly handicapped in neurological functions. I don't know if that means they're making progress without reading all of those articles, but they're still working on it.