According to Sebastian Alvarado, a postdoctoral researcher in Stanford University, the origins of superheroes such as Captain America is not really farfetched as it seems, in fact most of it could be explained by science and, on paper, could be achieved. Alvarado discovered that the creation of Captain America could be explained by epigenetic and genome-editing. Epigenetic involves switching on or off certain base pairs of DNA or RNA, which changes the DNA sequence and consequently change the characteristics of its carrier, while Genome-editing is a mechanism that allows certain genes to be manipulated. Seeing that there are specific genes that are responsible for increasing muscle mass, improving the body's circulatory system and the oxygen carrying load in the blood (that would eliminate the excessive build up of fatigue building poison in the muscles) and developing a more intelligent and strategic mind, genome editing tools like zinc finger nucleases or CRISPR/Cas9 systems could be used to selectively seek out and turn on these genes to bring into being a super soldier!
As for the utilization of "Vita Rays" to trigger the Serum ingested by the Cap's body, is closely related to the use of specific wavelengths, such as UV light - which is commonly used today, to release, activate and stabilize the chemicals or instructions held in a capsule, says Alvarado.
http://news.stanford.edu/news/2014/august/marvel-heroes-alvarado-081214.html
http://www.gmanetwork.com/news/story/375833/scitech/science/the-hulk-and-captain-america-the-real-science-behind-marvel-comics
http://www.techtimes.com/articles/13358/20140818/the-science-behind-captain-america-and-the-incredible-hulk.htm