[Artificial blood is a thing](https://en.wikipedia.org/wiki/Blood_substitute
). As you can read on the wiki, the issue is that we don't have a good way of getting it to transport oxygen, which is obviously a pretty vital function of blood. Also, as you can read, clinical trials for that are on currently ongoing.
While 'blood substitutes' certainly exist, they're not safe for regular use; haemoglobin (the main component in human blood) *loves* to bond with oxygen, which means that there's almost nothing left to oxygenate the tissues. Free-cell haemoglobin also damages the kidneys, and acts as a vasoconstrictor when it consumes nitric oxide.
Researchers have experimented with using stem cells to create 'artificial blood' for many years now, but human trials only started in 2013, and so far, 'pharmed' blood (the technical term for the product and process) is expected to be limited to military use for a number of years.
100% artificial blood is a thing, but it's :
-complicated to make : 100% man made,
-complicated to use : it transports oxygen, but you need to get that oxygen from somewhere, like a bariatric chamber,
-complicated to store : has to be frozen and thawed when needed, which takes time,
-some had [annoying side effects like heart failure.](http://circ.ahajournals.org/content/90/1/114
Hemoglobin based artificial blood is even more annoying because including all of the above, hemoglobin by itself (without the red blood cell all around it) will damage your veins and organs.
And finally even if you make something that can transport oxygen it also needs to release it where it's needed, and that's a whole new brain tangler.
So yes, producing artificial blood is a thing, it's been a thing since a long time ago, many failed to do it, many more are trying to do it now.
Blood is not a "thing", it's **alive**. It's zillions of tiny, living, human cells in a liquid. We've got lots of artificial replacements for the liquid, but you still need the human cells to stay alive. The thing that makes human cells best is, you guessed it, humans. Gracious donors such as yourself are essential to provide living, healthy blood cells to treat other people. You're unlikely to be replaced any time soon.