I’ve been thinking about have a PRP injection into my elbow to help heal a bad case of tennis elbow. When I looked on-line I found your Patient Guide to Platelet-Rich Plasma Treatment. I work in a lab in a hospital so I know that preparations of this type are not all equal. How do I know I’ll be getting the exact right mix for my problem?

You are exactly right to suggest not all injections of platelet-rich plasma (PRP) are the same. And you bring up a second challenging factor in using PRP for tendon problems: knowing how much to inject and providing the exact right ratio of leukocytes (white blood cells) to platelets.

As you know from reading our Patient Guide to Platelet-Rich Plasma (PRP) Treatment, PRP 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.

Researchers are investigating what is the best “recipe” for this product. There are looking to see if there is some amount of platelets and white blood cells that will give the best results. Right now, the exact ratio for optimum outcomes is unknown.

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.

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. On the other hand, 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.

And as someone who is familiar with lab procedures, you know it will be important to compare different preparations created with different systems. Different centrifugal speeds, varied plasma volumes, and number of spins could each have a unique impact on the final product. If there is a possibility of a superior product, patients and surgeons will want to know.