Indeed there have been adjustments in the no blood stance of JWs that correspond with the advancing medical processing of donated blood.
At first blood was transfused with no processing at all (whole blood). That was and is still rejected as a violation of biblical directives.
However blood can now be separated into all of its many components. Once that process goes beyond the 4 major components ( red blood cells, white blood cells, platelets , plasma ) the use of blood fractions becomes a conscience matter for each individual to contemplate prayerfully before deciding yes I will accept that or no I will not accept that.
In the book "Keep Yourselves in Gods Love"
there is the following information that lays out the current guidelines regarding Jehovah's Witnesses and the medical use of blood and blood fractions:
Blood Fractions and Surgical Procedures
Blood fractions. Fractions are derived from the four primary blood components—red cells, white cells, platelets, and plasma. For example, red cells contain the protein hemoglobin. Products developed from human or animal hemoglobin have been used to treat patients who have acute anemia or massive blood loss.
Plasma—which is 90 percent water—carries scores of hormones, inorganic salts, enzymes, and nutrients, including minerals and sugar. Plasma also carries clotting factors, antibodies to fight disease, and such proteins as albumin. If someone is exposed to a certain disease, doctors might prescribe injections of gamma globulin extracted from the plasma of people who already had immunity. White blood cells may be a source of interferons and interleukins, used to treat some viral infections and cancers.
Should Christians accept therapies incorporating blood fractions? The Bible does not give specific details, so each one must make his own conscientious decision before God. Some would refuse all fractions, reasoning that God’s Law to Israel required that blood removed from a creature be poured “out on the ground.” (Deuteronomy 12:22-24) Others, while refusing transfusions of whole blood or its major components, might accept treatments involving a fraction. They may reason that at some point fractions that have been extracted from blood cease to represent the life of the creature from which the blood was taken.
When making decisions about blood fractions, consider the following questions: Am I aware that refusing all blood fractions means that I will not accept some medications that include products to fight diseases or that might help the blood to clot in order to stop bleeding? Could I explain to a physician why I reject or accept the use of one or more blood fractions?
Surgical procedures. These include hemodilution and cell salvage. In hemodilution, blood is diverted from the body, replaced with a volume expander, and later returned to the patient. Cell salvage captures and returns blood lost during surgery. Blood is recovered from a wound or a body cavity, washed or filtered, and then reinfused into the patient. Because the methods of applying these techniques can vary from physician to physician, a Christian should find out what his doctor has in mind.
When making decisions about these procedures, ask yourself: ‘If some of my blood will be diverted outside my body and the flow might even be interrupted for a time, will my conscience allow me to view this blood as still part of me, thus not requiring that it be poured “out on the ground”? (Deuteronomy 12:23, 24) Would my Bible-trained conscience be troubled if during a medical procedure some of my own blood was withdrawn, modified, and directed back into my body? Am I aware that refusing all medical procedures involving the use of my own blood means that I would not accept a blood test, hemodialysis, or a heart-lung bypass machine?’
A Christian must decide for himself how he will allow his own blood to be handled in the course of a surgical procedure. The same applies to medical tests and current therapies that involve extracting a small amount of one’s own blood, perhaps modifying it in some way, and then reinjecting it.