The international medical community was excited when the British scientists announced their stem cell differentiation successes. Their excitement turned into ecstasy when the American scientists announced their method of stem cell production. Both major obstacles to stem cell regenerative treatments had been eliminated, and for the first time, growing entire human limbs from scratch seemed more reality than science fiction. This reality manifested itself a few months later, when the American and British scientists, working together, succeeded in growing a new arm for an amputee war veteran. There were still some kinks to work out in the methodology; the new arm wasn't a perfect replica of the veteran's lost arm. However, it was fully functional, and attaching it to his arm stub went better than expected. Being marginally asymmetric proved far preferable to lacking an arm.
This medical success was widely publicized, and reactions from the general public were mixed. Some were thrilled by the prospect of stem cell regenerative treatments being used more broadly. Others had ethical concerns about the use of stem cell regenerative treatments in certain domains. Almost nobody disapproved of lost limbs being regenerated, but some skeptics voiced concern about the use of stem cells to treat brain ailments. They worried that stem cell treatments might fundamentally change personalities or cause undesirable side effects. Similarly, some were leery about stem cell treatments of major cuts – these injuries would heal on their own in time, but there was no guarantee that potential side effects of stem cell treatments would be temporary.
Amidst the public debate, the scientists had already succeeded in creating many other functional body parts, including legs, bones, hearts, and lungs. The fact was that stem cell regenerative therapy was the medicine of the future. Scientists and governments were in agreement that the benefits outweighed the risks. There was every reason to expect that stem cell treatments would revolutionize medicine, and the worst side effects witnessed thus far were the slight asymmetry caused by the veteran's replacement arm.
Teams of scientists from all over the world began synthesizing human body parts in their own laboratories and publishing their results. The various teams quickly started coordinating their efforts so as to cut down on redundant work – there was no need for five different teams to independently discover how to grow livers, for example. On the international stage, this degree of teamwork was rare. It seemed that the sheer magnitude of these medical advancements, as well as their clear benefits for the entire human race, fostered an unusual spirit of cooperation. By the middle of 2018, most individual human body parts had been successfully grown in a lab.
During this process, many more patients volunteered to help test stem cell regenerative treatments. The only negative side effect was slight awkwardness due to imperfect body part synthesis, and this problem was diminished quickly as scientists improved their methods. Regenerative medicine was progressing faster than anyone had hoped possible, in large part because of the impressive international cooperation.
Given how quickly regenerative medicine had advanced, some of the scientists suggested that it may be possible to cause people's wounds – even major ones – to heal automatically, outside of a laboratory setting. This was obviously possible for cuts, scrapes, and other wounds that heal naturally; for these injuries, the objective would simply be to speed up the healing process. However, these ambitious scientists wanted to use stem cell regenerative methods to heal injuries that the human body isn't naturally equipped to handle, such as severed limbs.
Several years ago, these suggestions would have been met with derision. But in just over a year, regenerative medicine had progressed from relative infancy to the point where new, functional limbs could be grown in the lab. The various scientists and governments working on stem cell regenerative methods were mostly in agreement that researching auto-healing techniques was a good idea. Leaders from the US, Europe, Australia, Russia, China, India, South Korea, and Japan held meetings to discuss how best to proceed. Their scientists had already worked together quite well in an unofficial capacity – why not make the collaboration official? The result of these meetings was an international team of scientists assembled to research Stem Cell Auto-Regeneration, abbreviated as SCAR. The research team was appropriately dubbed Project SCAR.
The first challenge faced by Project SCAR was that MU gas, being a gas, would simply diffuse into open air if not confined by laboratory equipment. A necessary condition for on-site stem cell production – and by extension, for SCAR – was to prevent the gas from escaping. The boiling point of MU gas was far too low for condensing it into liquid to be viable. The most obvious way of trapping the gas was to store it in a separate container to be carried on one's person. People would then need to somehow supply the sealed container with energy to produce stem cells, and then apply the cells to their wounds. There were numerous problems with this methodology. Taking advantage of SCAR this way would require people to carry containers that were liable to break and release the MU gas. It also seemed that it would only be possible to heal one wound per container of gas – and it wasn't clear that this would be enough to heal major wounds.
Eventually, one of the scientists had the clever idea to store MU gas within people's bloodstreams. He had this idea when he realized that MU gas did not react significantly with the components of human blood. If someone with MU gas in their bloodstream sustained an external wound, the resulting blood would automatically provide MU gas to the wounded area. The gas would not be able to escape due to being trapped in aqueous form within the blood. Whereas carrying around a separate container and then applying stem cells to a wound required effort, storing the ingredients for stem cells within one's blood would allow for true auto-healing.
There was just one obstacle: even if aqueous MU gas was present at a wound, producing stem cells and healing the wound would still require that the gas be supplied with energy. Auto-healing could not occur unless both MU gas and energy were automatically supplied in response to a wound.
Scientists noted that from the standpoint of blood chemistry, the main change that occurred in response to an external wound was that blood came into contact with air. This led some to suggest that the necessary energy could be created via an exothermic reaction between blood and air. Using a combustion reaction between blood and oxygen would not be wise; blood is naturally oxygenated within the body even when no injuries occur, so producing energy via combustion would also result in constant internal combustion. Since combustion was off the table, Project SCAR produced two chemicals that did not react with human blood: one would react exothermically with atmospheric nitrogen, and the other would serve as a reusable catalyst for this reaction. A complete SCAR serum could be created by trapping MU gas, fuel, and catalyst in aqueous solution and injecting the solution into the bloodstream. In response to a wound that draws blood, the fuel and catalyst would come into contact with gaseous nitrogen, causing an exothermic chemical reaction – not strong enough to cause any harm, but strong enough to induce stem cell production. The MU gas would produce stem cells exactly where the injury occurred, and the cells would begin differentiating to patch up the wound.
Project SCAR had arguably achieved its objective: they had created a blood supplement that would cause people's wounds to automatically heal. Theoretically, even severed limbs could be regenerated this way. Unfortunately, early testing revealed an important downside: this particular method of healing did not use resources efficiently. The various chemical reactions all took place in open air, so plenty of the heat produced by the nitrogen reaction simply escaped. Furthermore, although trapping the MU gas in aqueous form was effective, the presence of heat caused plenty of the gas to evaporate away as steam instead of forming stem cells. This was all problematic because a single injection could only pump a finite amount of SCAR serum into the bloodstream. Severe injuries might only partially heal before the serum was used up.
The last crucial breakthrough for auto-healing occurred when a few of Project SCAR's scientists discovered how to produce more MU gas in the bloodstream using chemicals produced naturally in abundance in the human body. Specifically, they learned that more MU gas could be produced by catalyzing reactions between vitamin D and several natural components of human blood. Vitamin D was a desirable reactant for these purposes because the human body produces it in response to sunlight, and a typical amount of daily sun exposure produces much more vitamin D than is needed for natural bodily functions. Conversely, the blood components used in these reactions are naturally produced by the body when it detects that their levels in the bloodstream are too low. Furthermore, the scientists were able to find catalysts that are not consumed in these reactions. Thus, they had discovered a way for the body to continue producing more MU gas in the bloodstream so long as it had regular access to food and sunlight. The scientists completed their renewable SCAR serums by adding the catalysts for the vitamin D reactions to the injection. In total, the finalized SCAR serum consisted of MU gas, reactants and catalyst for the nitrogen reaction, and catalysts for the vitamin D reactions.
One final problem never manifested. There was brief concern that if the vitamin D reactions occurred continuously, the chemical products – that is, MU gas – would reach harmful levels in the blood and act as a toxin. As it turned out, the vitamin D reactions needed a substantial amount of energy to occur, even in the presence of catalysts. Therefore, levels of MU gas in the blood would ordinarily hold steady. But when an injury occurred and the exothermic nitrogen reaction began, MU gas would be produced as needed until the injury had healed.
By now, it was spring 2019. Project SCAR was a huge success – in a little more than a year, they had produced a relatively inexpensive serum that could automatically heal the most serious of injuries. Experiments on rats and human volunteers with grievous wounds suggested that the SCAR serum was effective and had no major side effects. That summer, the SCAR serum was approved for public use, although those with existing medical conditions were advised to hold off on receiving the SCAR serum pending further testing. The commercialization of auto-healing prompted more ethical concerns, and plenty of people opted not to receive injections out of fear – fear that would later prove to be justified. But others delighted over the thought of being nearly impervious, and this led to about 15% of people in developed nations receiving the injection immediately.