A stocking is traditionally filled with candy, fruits, coins, etc. Small objects of equally small economic value. The emotional value is definitely there, especially since Christmas tends to bring out the best in people.
Studio Inbetween, from Germany has a different take on things. Why not fill the stocking with something more valuable? Something that is really necessary. Fill it with blood. In this case, blood works as a metaphor for life. So instead of giving something material with little value and some emotional charge, we give ourselves (or at least a part) as a gift to make someone in need better. This has a lot more emotional value than coins or candy and it has a definite purpose.
Since the design is thematic or seasonal, and hospitals like to be serious, it’s not likely to be adopted anytime soon. The playful nature of the transfusion bags would definitely clash with the professional impression hospitals try to make.
Personally, I like the object as such. But as I see no commercial value to it, so it’s something that would be better fitted at an exhibition or museum, an experiment in design. A good experiment.