EXPERIMENTAL AND CLINICAL TRANSPLANTATION

In ancient times, religious traditions considered urine a useful distilled product from the body. It has been used as a form of medicinal therapy for many years and is still used by millions of people worldwide who drink their urine for therapeutic purposes. The positive effects of urine on health were reported since the Renaissance for its bactericidal effects on wounds, healing effects on gastric ulcers, improved protein synthesis, regression of liver tumors, and ability to block the growth of tuberculosis mycobacteria. Urine contains a large number of chemical agents, some of which have already been identified, although others are still unknown. It is important to identify these agents through new technological methods, such as mass spectrometry, as new biomarkers of diseases. Recently, the use of urine has been discovered as a “green” element to produce electricity, agriculture fertilizers, generation of water, and building material for lunar bases for future space explorations.

Key words : Mass Spectrometry, Urea, Urine therapy

Use of Urine in the Past

In ancient times, urine was considered a sacred element in Hindu and Tantric religious traditions. It was not considered a waste product of the body but a distilled product selected from the blood that contained useful substances for body care.^1-4 The Sanskrit book Shiwambu’ Kalpa Vidhi, dating back to 5000 BC, reports the medical advantages of urine, as do Sumerian texts (4000 BC). The Assiro-Babylonian reported that a woman’s urine mixed with alcohol could be used to detect and predict pregnancy. Egyptians identified diabetes from urine; the Erbes Papyrus (1552 BC) reported urine excess as an indication of diabetic nephropathy. Essenes and Christians used urine for body massage.^1-4 Galeno (129-216 BC) suggested urine for the treatment of burns, inflammation, and skin disease, whereas Hippocrates (~460 to ~370 BC) proposed urine to treat gonorrhoea and tuberculosis. The Byzantine Theophilus Protospatharius (~7th century), Paracelsus (1493-1541), the Sicilian Diodoro from Sicily, and the Venetian Tomaso Catullo (1782-1869) were all supporters of the use of urine for medicinal purposes.1-4 In Medieval times, it was common to taste urine for the presence of sugar. In the Renaissance, it was reported that patients with skin cancer recovered by using urine from people who ate cabbages.^1-4

In 1773, urea was isolated from urine by the French chemist Hilaire Marin Rouelle (1718-1779); in 1828, it was synthesized by the German chemist Friedrich Wohler (1800-1882). Urea was considered an essential component of urine and, over the years, was prescribed for its bactericidal properties, improving protein synthesis and treating liver tumors, infections, asthma, hypertension, and AIDS.^1-4 In Paris, at the beginning of the 18th century, dentists prescribed urine to treat various oral diseases; in Europe, urine was used as a defense from the plague.⁴ Urea is present in sweat as a key molecule of the epidermal natural moisturizing factor that modulates the DNA synthesis of epidermal cells through gene regulation.^5,6

Modern Uses of Urine

Besides urea, urine contains many other substances, some of which have already been extensively studied, whereas others remain unknown. Therefore, urine analysis could represent a relevant noninvasive procedure of examination, not only in nephrology but also in medicine in general. Clinical proteomics has been at the center of attention for discovering new biomarkers by using mass spectrometry (MS) and has been applied to the detection of urine proteomics.^7-11 Urine may be an emerging and prominent tool in the field of nonblood clinical bioanalysis. In fact, with urine MS, laboratory studies have identified several nonblood biomarkers specific for renal diseases such as diabetic nephropathy, IgA nephropathy, focal segmental glomerulosclerosis, lupus nephritis, membranous nephropathy, acute kidney injury, renal Fanconi syndrome, and renal allograft rejection. Thus, it is possible to affirm that MS-based urinary proteomics has considerable potential in developing noninvasive diagnostics in the future. Recent research from the Massachusetts Institute of Technology has fine-tuned a multimodal nanosensor engineered to target tumors through acidosis, respond to proteases in the microen-vironment to release urinary reporters, and carry positron emission tomography probes to enable localization of primary and metastatic cancers in mouse models of colorectal cancer.¹² This multimodal sensor can be employed longitudinally to assess the disease burden noninvasively, including tumor progression and response to chemotherapy.

Future Uses of Urine

The future of urine is represented by its “green” importance in producing electricity, fertilizer in agriculture, potable water, and building lunar bases for future space explorations. Dutch researchers have discovered a bacterium capable of transforming urine ammonia into hydrazine, making it possible to use urine as a replacement for fuel in gasoline-dependent vehicles.^2-4 Researchers have also created a low-cost portable battery that is recharged by urine.^2-4 Researchers at the University of the West of England, who have recharged cell phones by urine, concluded that 600 mL of urine produce enough energy for 3 hours of phone calls on a smartphone.^2-4 Rio de Janeiro was illuminated during the Carnival by urine, which powered turbines connected to urinals placed throughout the city. Moreover, urine can replace chemical fertilizers because the urea content in the urine is made up of 46% nitrogen, which produces high-speed growth of plants.¹³ Urine represents a reasonable amount and important reserve of water, together with the humidity of breath and the sweat of the skin. Seven billion inhabitants on earth produce 10 billion liters of urine every day, enough to fill 4000 Olympic-sized swimming pools. Another important use of urine is represented by its future in the space conquest in line with the philosophy of the international space agencies of “in situ resource utilization.” Transporting 1 pound of materials in orbit costs around 10 000 dollars, and, to reduce transportation costs, American (NASA) and European (ESA) space agencies have directed their attention to urine. NASA spent 250 million dollars to construct a machine capable of producing 23 liters of water per day, reusing astronauts’ urine for drinking and providing the shuttle’s humidity.

Recently, urea from urine has been identified as an accessible superplasticizer to build lunar bases with geopolymer mixtures. It has been proven that a mixture of urea and lunar dust, named regolith, can be used to build walls for lunar bases that are very resistant to high levels of radiation and extreme and wide fluctuations in temperature (-120 to 120 °C), as well as having strong fire resistance, low thermal conductivity, and resistance to vacuum and meteoroids.^14-18 Additional evidence indicates that urine from astronauts can be used to obtain water for lunar bases and to cultivate rice, soy, potatoes, and wheat using urea from urine as fertilizer.¹⁹ Recently, Dutch researchers have discovered a method of making space fuel from urine suitable for rockets and vehicles to travel in space.^2-4 In this article, the characteristics of urine were reviewed and show support for the saying of Greek philosopher Heraclitus of Ephesus (535-475 BC) that “nothing is created, nothing is destroyed, everything is transformed,” in accordance with the mechanistic views of the atomist Democritus (460-370 BC), Anaximenes (560-525 BC), and Anaximander (610-547 BC).

Thus, the kidney appears to be a productive “green” organ for ecofriendly applications through the urine it produces.

Volume: 21 Issue: 6 June 2023 - Supplement - 2

FULL TEXT