Throughout history, the human body has been the subject of endless scrutiny and surprise. Many people are confused about the functions of all these organs and fluids found inside. This includes the purpose of blood, which considers itself to be ignored just to "cool the body", but is responsible for regulating the body's fluids, leading to the practice of bleeding and other problematic therapies. However, with the advancement of medical science, we have come to a completely different view.

In short, our circulatory system and the blood within it enable us to exist large multicellular organisms. It delivers oxygen and nutrients to cells, while removing waste products, and provides a simple way for the cells that make up our immune system. Our blood and related tissues are vital to healthy living. This becomes very clear when we talk about injuries and surgeries that involve severe blood loss.

Although the practice of transfusion from donated blood makes a huge difference here, storing every type of blood is not always easy, especially in remote hospitals, ambulances or war zones. Here, the use of artificial blood—without complicated storage requirements and the need to balance blood types—may be revolutionary and can save countless lives, including those whose religion prohibits blood transfusion.

Although great progress has been made in this field, the number of practical products is limited, but it turns out that finding an alternative that meets all the conditions needed to make it universal and safe is still a challenge.

Although there were reports of the Incas performing blood transfusions between people as early as the 16th century, it was not until William Harvey (1578 – 1657) described the characteristics of the human circulatory system and blood in the 17th century that the modern view The study of human physiology began to take shape. This is accompanied by blood transfusion experiments conducted mainly between animals.

In 1665, doctor Richard Lower gave a rough blood transfusion to two dogs. After the operation, it apparently had no adverse effects on any animal. Around this time, blood transfusions from animals to humans (xenotransfusions) were also tried. Many human subjects did not survive, possibly because the body rejected this foreign blood.

Problems similar to heterogeneous blood transfusions occur in human-to-human blood transfusions: although sometimes this will work, sometimes the recipient will be adversely affected and some people will die as a result. This led to the notoriety of blood transfusions in the 19th century. It was not until Karl Landsteiner discovered three human blood types (A, B, O) in 1901 that the interpretation of these results became clear.

When incompatible blood types are mixed together, one can clearly observe how red blood cells clump together. At that time, it was easy to imagine what would happen in the human body if this reaction occurred during a blood transfusion. This insight led to the first of many revolutions that will make blood transfusion as safe and common as it is today.

The obvious complication of trying to replicate the function of human blood is that we are trying to rebuild something that has evolved over millions of years in a larger system (the body) that depends on many aspects of it to function properly. Even if it does not intend to stay in the body longer than the time required for natural blood levels to recover, it cannot be allowed to cause more damage than it prevents.

In humans, blood accounts for about 7% of total body weight. Its density is about 1060 kg/m3, which is very close to 1000 kg/m3 of water. An adult has about 4.5 L of blood on average, including about 45% of red blood cells, about 54.3% of plasma, and about 0.7% of white blood cells. Generally speaking, each of them forms the three main functional groups of blood.

Red blood cells contain hemoglobin combined with oxygen. White blood cells (along with antibodies) constitute the main part of the immune system. Plasma contains nutrients, electrolytes and clotting factors, which can maintain cells and allow the following methods to repair damage and coagulation. From this we can infer what is needed for blood substitutes: what is essential is the function of red blood cells and a carrier fluid similar to plasma (about 95% water).

Although the latter is relatively simple in the form of crystal solutions (such as saline solution), the complexity comes from the function of replacing red blood cells. There are two methods that have been mainly researched and (limited) used: oxygen carriers based on perfluorocarbon and hemoglobin (PBFOC and HBOC, respectively).

What makes oxygen carriers with red blood cell characteristics become complicated is that these molecules should not only be combined with oxygen, but should also be easily supplied to body tissues. The obvious idea here is to synthesize hemoglobin and use it directly. The obstacle is that hemoglobin itself has a very high affinity for oxygen, has a short half-life in the blood, and can damage the kidneys. In red blood cells (RBC), hemoglobin accounts for only 33% of the cell mass, and the remaining mass is used to stabilize hemoglobin.

For this reason, HBOC using normal hemoglobin will be useless because it cannot provide enough oxygen to the tissues. To solve this problem, hemoglobin must be stabilized in a way that still allows binding to oxygen, while not inhibiting its distribution to tissues. Many companies have worked hard to bring this type of HBOC to the market. Among them, HemAssist (provided by Baxter Healthcare), Hemolink (Hemosol, Inc.), and Hemopure (Biopure Corp) have either failed during the trial period or failed shortly after entering commercial sales.

Common problems observed include vasoconstriction, which may be caused by the binding of hemoglobin to nitric oxide. Most of these HBOCs are targeted for use in non-human animals, and the increase in mortality has prevented these products from passing medical tests or being withdrawn from the market within a few years.

In contrast, there is a PFBOC approved by the FDA: Fluosol-DA, such as Sutherland et al. (1984), reported its effectiveness on cats, and Ohyanagi et al. (1984) About the effectiveness of Fluosol-DA 20% infusion to patients of Jehovah's Witnesses. Because the latter group’s religious beliefs lead them to refuse blood transfusions, etc., medical care may be problematic.

Even so, the complexity of Fluosol—patients must breathe pure oxygen in order to “load” enough oxygen for PFBOC molecules—and its complex storage (freezing) and handling requirements, led to the suspension of production in 1994.

Although there have been many setbacks in bringing solid blood substitutes to the market over the years, the demand for such a solution is too great to stop research. This allows us to understand current developments and the US military is one of the interested buyers of these blood substitutes. Not only for oxygen carriers, but also for synthetic platelets (for coagulation) and dry plasma.

The main selling points here are to extend the shelf life, remove complicated blood type matching, reduce the possibility of allergic reactions, and so on. Although we have come a long way from the early days of blood transfusion, we still rely on blood donation and the system for processing this blood. Although it is a system that saves countless lives every year, it also has the disadvantages of complicated logistics, short shelf life, and possible contamination of blood.

The advantage of synthetic blood is that it can be produced in any quantity required under strictly controlled conditions. For example, another advantage of PFBOCs is that their molecules are much smaller than RBCs, which allows them to even bypass blockages and contractions in arteries. This will allow tissues to be oxygenated, otherwise these tissues will eventually die due to hypoxia, which can prevent necrosis, amputation and other traumatic complications.

Although the optimism about blood substitutes in the late 20th century seems to have calmed down after so many setbacks in the past few decades, we have learned a lot, not only what does not work, but also what works. We have also obtained a lot of important information about human physiology, which helps to increase our understanding of the cardiovascular system.

Hundreds of years ago, it was thought that sheep blood, even alcohol or urine could be a good substitute for human blood. Today, we understand the many complexities of blood typing, can process donated blood to use only red blood cells, plasma or platelets, treat a variety of medical conditions, and so on. As blood substitutes have been reduced to a major medical engineering problem, we may see progress here soon.

And to feed the vampire, don't forget to establish the vampire's nutrition. Consider that a good artificial vampire smoothie can save the lives of countless virgins!

There are no more vampires.

During the hippie free love movement in the 1960s, we ran out of virgins>

You can thank my generation in the future... :)

One thing about free love is that you have many virgins.

If we implement LastDay, then when people go to Carousel, they can suck blood first. Although part of the longevity is brought about by blood transfusion, if people are terminated at 30, you will need less spare blood

I took imdb.com and _Soylent Green_ and retrieved it. In doing so, I learned that Soylent Green will happen next year, 2022. :-)

Great movie.. The age in the book is 21. Unfortunately, the actors are past that age, so the movie is changed to 30 years old.

In fact, this is not bad. People used to say that life starts at the age of 30.. https://en.wikipedia.org/wiki/Logan%27s_Run

Or 66 if we include that song... :)

Hmm...I can't help thinking that genetically modified pigs can be used as donors. This can easily maintain the vitality of the blood because it is only in the pig's body.

Ordinary pigs have been used as donors, why not?

My beef (!) for this article is the unit! I really need to know what my fluid ounce is for my black pudding recipe.

Well, if the herbivores succeed, we can still save pig breeds by using them as blood and organ donors. This is the problem of vegans. They want us to extinct animals without eating them. So let us kill them and collect their blood for other purposes, even if the black pudding is bad but we don't allow it.

Oh yes, just like all "almost extinct" species before humans chewed them to save them. /rolls_eyes.gif

The idea of ​​your question assumes that there must be no reason for the existence of animals that are useless to humans; one of the reasons why the world is in such a terrible situation...

Mosquitoes, cockroaches and viruses (involuntary "things", but still) don't have any business, no. The rest will be used in biotechnology. No, the reason the world is so bad is because the economy is monopolized in the hands of private participants who only care about profit.

In my high school chemistry class, the teacher took a class on the use of artificial blood in the Vietnam War (I am an American). It is made from coconut milk because it is loosely combined with oxygen. I am sure that it will be researched and improved from then on.

If I remember correctly (always suspected) there are a few key details that are different.

Use coconut water, the clear juice from the coconut. Coconut milk is a juice mixed with coconut milk; it is too thick for blood. Coconut water happens to be sterile, never exposed to the air, very close to 0.9% saline (normal saline), about 5% to 10% glucose.

This makes it very close to what is used in many hospitals.

That is the amount of fluid, not the blood that delivers oxygen. It allows the body to have enough blood pressure and hydration to allow the heart to pump out (remaining) blood and blood cells, and lose blood volume due to injury, but this fluid does not really transport oxygen like blood cells.

Although there is not much benefit to improving storage requirements or infection control, an interesting way is to "universalize" donated blood to avoid the problem of type rejection. For example, by adding molecules that bind to antigens and express different antigens, and remove antibodies from the donated plasma, all donated blood cells are effectively converted into O-groups, and all plasma is effectively converted into AB groups.

Ehh just uses cotton bolls from hummingbirds from the Andes region.

Damn it, I mean the blood formed a hummingbird that lives in the Andes of South America.

Please be kind and respectful to help make the comment section great. (Comment Policy)

This website uses Akismet to reduce spam. Learn how to handle your comment data.

By using our website and services, you explicitly agree to the placement of our performance, functionality and advertising cookies. Learn more