Artificial blood and skin would be useful because obtaining donors for blood and skin can be difficult. These artificial tissues and fluids would need to be accepted into the body as self-cells so as to not be rejected by the immune system.
Work Step by Step
Real tissues work better due in part to immune system compatibility and in part due to the difficulty in making artificial tissues that actually function as well as real ones. The issue with obtaining real tissues, however, is finding donor individuals or donor sites on the same individual.