Lea Zila was poring over vials of golden-hued plasma in a Cedars-Sinai lab when the patterns began to emerge—tiny biological signatures that could hold the key to unlocking why some arthritis patients find relief in their own blood while others see no change. At the heart of this investigation is platelet-rich plasma (PRP), a treatment derived from a patient’s blood and increasingly used to ease the grinding pain of knee osteoarthritis, a condition affecting over 32 million Americans. Yet despite its growing popularity, PRP remains controversial—largely because it doesn’t work for everyone. Now, for the first time, researchers at Cedars-Sinai in Los Angeles have identified measurable biomarkers that may predict who will respond to the treatment.
The process is straightforward: a patient’s blood is spun in a centrifuge to isolate and concentrate platelets and plasma, which are then injected into the arthritic knee in hopes of reducing inflammation and stimulating tissue repair. But as Dr. Dmitriy Sheyn, associate professor of orthopedics and surgery at Cedars-Sinai, explains, “The biological makeup of platelet-rich plasma varies between individuals and might influence how well the treatment works.” In their study, published in the Orthopaedic Journal of Sports Medicine, Sheyn and his team analyzed the PRP composition of patients before treatment and tracked their outcomes over time. The results were revealing—about 60% of participants reported reduced pain and improved knee function, a meaningful gain for those struggling with mobility. But the real breakthrough came when the researchers noticed a consistent trend: those who responded well had lower levels of specific immune cells and inflammatory proteins in their PRP, while non-responders had higher concentrations.
This discovery shifts the conversation from whether PRP works to why it works—for some. “We are finally beginning to understand the active ingredients in this therapy,” said Dr. Bert Mandelbaum, professor of orthopedics and senior author of the study. Though the study was small and lacked a placebo control, its implications are significant. For decades, osteoarthritis treatment has relied on pain management and, ultimately, joint replacement. Regenerative therapies like PRP offer a promising alternative, but without predictability, they remain a gamble. Now, with these biomarkers in hand, clinicians may one day screen patients before treatment, personalizing care and improving outcomes.
Beyond prediction, this research opens the door to engineering more effective, standardized versions of PRP—treatments designed not from guesswork, but from the body’s own biological signals. As the team continues to validate their findings, the hope is clear: to turn a variable therapy into a precise science, one biomarker at a time.