Chronic kidney disease (CKD) is the leading cause of death in older cats. It’s so prevalent that I’ve come to believe that basically every cat over a certain age (I’m not sure what that age is … maybe 10ish or so) suffers from at least a touch of CKD. Just because we can’t pick it up in its early stages, doesn’t mean it’s not there.
Urine concentrating ability doesn’t decline until two-thirds of kidney function is gone, and blood parameters (e.g., creatinine and blood urea nitrogen or BUN) don’t rise until cats have already lost three-quarters of their kidney function.
CKD develops when the kidneys can no longer fully perform some or all of their normal roles in the body. These include filtering waste products from the blood, conserving water, balancing electrolyte levels in the body, helping regulate blood pressure, and producing a hormone that stimulates red blood cell production. Kidney function can be lost because of accumulated wear and tear and/or as a result of specific events that "knock out" a large number of nephrons at one time.
I hate dealing with CKD because, short of referring a cat for a kidney transplant, I can’t actually do much to heal my patient. Sure, I can tweak the diet, institute fluid therapy, prescribe medications to deal with some of the complications that arise, but in truth, I can do very little to slow the inevitable progression of the disease. That might be changing, however. Research into the use of stem cells for the treatment of feline kidney disease is providing some exciting, albeit preliminary, results.
Stem cells were not something we talked much about when I was in veterinary school. The field of study didn’t really get going until after I was out in practice, so I’ve had some catching up to do. The National Institutes of Health has a great Stem Cell Information website. It’s focused on the human side of things, but the basic information applies across species. To quote:
Stem cells have the remarkable potential to develop into many different cell types in the body during early life and growth. In addition, in many tissues they serve as a sort of internal repair system, dividing essentially without limit to replenish other cells as long as the person or animal is still alive. When a stem cell divides, each new cell has the potential either to remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell.
Stem cells are distinguished from other cell types by two important characteristics. First, they are unspecialized cells capable of renewing themselves through cell division, sometimes after long periods of inactivity. Second, under certain physiologic or experimental conditions, they can be induced to become tissue- or organ-specific cells with special functions. In some organs, such as the gut and bone marrow, stem cells regularly divide to repair and replace worn out or damaged tissues. In other organs, however, such as the pancreas and the heart, stem cells only divide under special conditions.
With funding assistance provided by the Morris Animal Foundation and Frankie’s Fund for Feline Stem Cell Research, Colorado State University veterinarians are currently studying the effect that intravenous injections of stem cells harvested from a cat’s own fat cells have on the kidney function of animals diagnosed with CKD. Check out the Morris Animal Foundation’s report on this potentially exciting new frontier in veterinary medicine, as well as an account from a preliminary study that gave one stem cell recipient a "new lease on life."
Dr. Jennifer Coates