Boston Lab Bioengineered Functional Kidneys

Lab-grown kidneys have been successfully transplanted into rats, functioning as normal kidneys.

Researchers at Massachusetts General Hospital in Boston have bioengineered functioning rat kidneys in the laboratory. This incredible achievement may eventually lead to the ability to create replacement organs, an virtually inexhaustible supply for people with kidney disease, who suffer from renal failure, or develop cancer.

Kidneys, located in the retroperitoneum of the abdominal cavity, are regulatory organs essential in the urinary system. They serve a homeostatic function balancing electrolytes, sustaining an acid–base equilibrium, and maintaining proper ratios of salt and water therefore regulating blood pressure.

The kidneys also produce hormones including calcitriol (hormonally active form of vitamin D), erythropoietin (glycoprotein responsible for red blood cell production), and the enzyme renin (component that regulates the body’s mean arterial blood pressure).

Cellular metabolism generates numerous by-products that require elimination from the bloodstream. These by-products are eventually expelled from the body during urination, the primary method for excreting water-soluble chemicals from the body. Urine is produced from kidney excreted wastes such as urea and ammonium. These bean shaped filters are also responsible for the reabsorption of water, glucose, and amino acids.

Kidneys are the body’s natural filter, screening the blood, which is fed through via renal arteries and veins. Each kidney removes waste which is then diverted to a ureter and travels to the urinary bladder.

Although not life-threatening, kidney stones (barbed, calcified deposits) are a painful nuisance and can be treated with medication and ultrasounds. A common symptom of kidney stones is a sharp, excruciating pain in the medial/lateral segments of the lower back. Immediate medical advice is recommended to insure it is simply a kidney stone and not something worse.

Kidneys, like any other biological mass composed of cells, are subject to disease and cancer; the most common is renal cell carcinoma. Cancers, cysts, and some other renal conditions can be managed with removal of the kidney (nephrectomy). People can survive with a single kidney.

When renal function is found to be persistently poor, dialysis and kidney transplantation may be necessary.

According to participating researchers and Dr. Harald C. Ott, senior author of the study paper published in Nature Medicine, the rat kidneys produced urine in the laboratory as well as when transplanted into rats. Although groundbreaking, the researchers admit the work is still in early stages, too early to create a fully functioning kidney for humans just yet, as issues such as bleeding and clotting need to be resolved first. But it hints at the future possibility.

The kidneys were created by stripping donor kidneys of their cells (decellularization), leaving behind a scaffold of collagen and other aspects of the extracellular matrix. The process uses chemical detergents to wash away native living tissue, leaving a network of proteins that retains the structure of the blood vessels and other components of the organ. New cells that regenerate tissue were added to the exposed framework.

To make the regenerated rat kidneys, human cells were implanted into the blood vessel portions of the organ, and kidney cells from newborn rats were used for the other parts. The kidneys were then put into an incubating chamber for up to five days, allowing the tissues to germinate. It took many attempts to establish the precise technique best used to feed the cells into the organ, as if it was growing in an embryonic rat.

According to the New York Times, About 17,000 people with end-stage kidney disease receive a donor organ each year in the United States, but more than five times as many patients are on waiting lists. In 2011, nearly 5,000 people died while awaiting transplants. Bioengineered kidneys, especially if made using nonhuman sources, could ease or eliminate this organ shortage.

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