Best “Recipe” for Treatment of Tendons with Platelet-Rich Plasma


Platelet-rich plasma (PRP) (also known as blood injection therapy) is a medical treatment being used for a wide range of musculoskeletal problems. Platelet-rich plasma refers to a sample of serum (blood) plasma that has as much as four times more than the normal amount of platelets. This treatment enhances the body’s natural ability to heal itself and is used to improve healing and shorten recovery time from acute and chronic soft tissue injuries.

It has been used for years after plastic surgery and surgery on the mouth, jaw, and neck. It seems to promote bone graft healing. Researchers have found a way to combine this substance with other chemicals to make it into a putty or gel that can be painted on a surgical site to speed up healing.

Blood injection therapy of this type has been used for knee osteoarthritis, degenerative cartilage, spinal fusion, bone fractures that don’t heal, and poor wound healing. This treatment technique is fairly new in the sports medicine treatment of musculoskeletal problems, but gaining popularity quickly.

And that brings us to the current dilemma facing researchers: what is the best “recipe” for this concoction? Is there some amount of platelets and white blood cells that will give the best results? What is that ratio? Now that we know platelet-rich plasma (PRP) treatment works, it’s time to refine the “formula” so-to-speak.

To aid in that research, veterinarians from Cornell University in New York are doing some studies using blood and tendon tissue from horses to investigate the effect of various platelet to white blood count ratios. They prepared and analyzed the results on healing for four different concentrations of platelet:white blood cells.

One reason this type of research is even needed comes from previous studies that showed a “Goldilocks effect” of platelet-rich plasma treatment. It has been observed that too low or too high a concentration of platelets yields inferior results or poor outcomes. This study is an effort to find the “just right” concentration of these two important ingredients in the platelet-rich plasma (PRP) treatment.

Other studies have shown that the exact composition of PRP does influence the amount of growth factor and catabolic cytokine concentrations, which in turn affect how well PRP works. Since platelets increase signals to stimulate healing and leukocytes increase molecules that signal inflammation, it’s important to study the way platelets and leukocytes influence the effects of PRP on tendon healing.

The hypothesis (theory) of these researchers was that having a product with reduced leukocyte (white blood cell) count or one with increased platelets would give the best results. Their specific task was to find out which combination of these two products gave the best results. They started with three groups that had the same amount of platelets but different levels of leukocytes (low, medium, and high). A fourth group with high platelets and high leukocytes was also included.

They found that the high levels of white blood cells (the leukocytes) caused increased inflammation. This was true no matter what platelet to leukocyte ratio used. Inflammation will delay or slow healing with the possibility of more scar tissue. At least from an animal model, it looks like reducing the amount of leukocytes in platelet-rich plasma (PRP) therapy might help stimulate the best healing response with the least amount of scar tissue. Increasing the amount of platelets does not counteract the inflammatory effect of the leukocytes.

Of course, this was just one set of differing concentration ratios and in animals with normal tendon tissue. More studies are needed to further define the optimum blend in humans and for different conditions.