Clinician calls for further study on platelet-rich plasma formulations and impact

• Orthopedics Today, September 2012

MONTREAL — While there is evidence of successful treatment using platelet-rich plasma for various pathologies, the lack of unfailing positive clinical outcomes points to variability among patients and materials, according to a lecturer at the International Cartilage Repair Society World Congress 2012.

In his lecture, Scott A. Rodeo, MD, described his and others’ clinical experiences with platelet-rich plasma (PRP). His message — more research is needed about these materials and understanding the variability inherent in PRP formulations, patients and their pathologies is key.

“One of the fundamental issues, as a clinician if you are thinking of using PRP, is the tremendous variability,” Rodeo, of the Hospital for Special Surgery in New York, said. “All PRPs are not the same. There is variability between the various commercial systems that are available. There is also variability, of course, within the individual patient and the underlying biology.”

Scott A. Rodeo

He noted that cytokines influence several biological aspects of connective tissue.
“Clearly, connective tissue healing requires a complex timing and sequence of cytokine expression, so the rationale and attraction of PRP is the ability to deliver numerous cytokines in potentially physiologically relevant proportions,” Rodeo said. “It is complex, and it is a bit of a leap of faith. In fact, despite vast basic science and laboratory data [that] demonstrate a positive effect of PRP on these tissues, this has not translated into a consistently positive clinical effect.”

Variability

A reason for this, Rodeo suggested, could be that PRP formulations differ among manufacturers and patients. Even within each individual, formulations can vary throughout the day.
With these variations, it becomes impossible to determine whether a formulation that works in one study will have the same effect in another patient for a similar application or what may be the content of a given formulation.
“What are we putting in the patient? With a drug, it is easy. We know it is a precise composition,” Rodeo said. “That contrasts with the PRP materials we are using in patients.”

Arthritis treatment

Although a number of studies have demonstrated a clinical improvement in symptoms after PRP injections for the treatment of arthritis, Rodeo noted that most of the data available refer only to the knee.
“There is little data for other joints,” he said. “Most studies do report better results in younger patients with lesser degrees of degeneration. The clinical effect typically wears off in 6 months to 12 months. There is little data demonstrating a positive structural effect — that is, actual cartilage regeneration — so it may be symptom-modifying but it is probably not structure-modifying.”
Rodeo noted that more research is needed about PRP.

“We certainly need more information,” he said. “Keep in mind, arthritis is a heterogeneous condition. The effect of a specific PRP formulation may differ significantly based on the underlying biologic or inflammatory milieu.”
He added, “Clinical results, clearly, are mixed. PRP seems to have the potential to be symptom-modifying, but clearly [it] does not appear to be structure-modifying.”
With regard to the variability of PRP, Rodeo noted clinicians must strive to understand what they are delivering to the patient. This means analyses of PRP samples, so these formulations can be correlated with clinical results.

“We know cytokines can increase production of matrix proteins, but a critical deficiency with all this work is that tissue microstructure is not reformed,” Rodeo said. “We do not regenerate normal cartilage, tendon or meniscus. [It] appears growth factors, such as PRP, still do not provide the proper cellular and molecular signals to truly drive regenerative healing. I would submit that both cells and the signals are needed to reconstitute both tissue composition and structure.” – by Robert Press

Reference:

• Rodeo SA. Clinical experience with platelet-rich plasma. Paper 15.1.3. Presented at the International Cartilage Repair Society World Congress 2012. May 12-15. Montreal.