Constituent microscopic parts of the organ, kidney glomeruli, were generated from human embryonic stems cells that were grown in culture dishes in a laboratory containing a culture medium nutrient broth made up of molecules to promote kidney development. They then were combined with a gel like substance that acted as a natural connective tissue and injected as a tiny clump under the skin of mice.
After a 3 month time frame examination of the tissue showed that nephrons had formed which are the microscopic functional and structural units of the kidney. The newly formed structures were observed to contain most of the constituent parts that would be present in human nephrons, which included Bowman’s capsule, proximal tubules, Loop of Henle, and distal tubules. Tiny human capillary blood vessels were observed to be formed within the mice which served to nourish the new kidney structures. The newly formed tiny kidneys were lacking in a large artery that without the kidney function would only be at a fraction of normal. The team began to work with surgeons in order to put in an artery that would bring more blood to the newly formed kidney.
To test functionality of the structures Dextran was used which is a fluorescent protein that will stain urine like substances that are produced when glomerular filtrate nephrons filter the blood, which was tracked and able to be detected in the structures’ tubules, which demonstrated that filtrate was for certain not only being produced but also was being excreted as urine. It can not be said with certainty yet as to what percentage of function exists.
It is very interesting that the structure made up of human cells developed great capillary blood supply that became linked to the vasculature of the mouse, and that it was formed from several hundred glomeruli while humans have about one million in the kidneys which is clearly a major advance. This work constitutes great proof of principle but there still is a great deal of work to be done, as an exit route for the urine and a way to deliver this technology to diseased kidneys needs to be developed.
It is estimated that worldwide there are close to 2 million people being treated with dialysis or transplant for kidney failure with another 2 million dying each year unable to access treatment.
