The sole reason why red blood cells are unable to replace damaged proteins is that red blood cells lack DNA and cell organelles such as the nucleus, ribosomes, and mitochondria which are crucial for protein synthesis, assembly, and repair. In other words, they lack both the information and the machinery for making or repair of proteins.
Due to lack of DNA and cell organelles, red blood cells cannot be able to satisfy the central dogma which summarizes synthesis of proteins as DNA → RNA → proteins.
DNA has the genetic information on how proteins should be made, RNA is responsible for transferring the information from DNA in the cell nucleus to the ribosomes in the cytoplasm, then translating or decoding this information, which results in the making of protein.
