Leukocyte-Rich Platelet-Rich Plasma, or LR-PRP, is a therapeutic preparation derived from a patient’s own blood that harnesses the body’s natural healing abilities. Its defining characteristic is a high concentration of two components: platelets and leukocytes. Platelets are small cell fragments in the blood known for their role in clotting, while leukocytes are the white blood cells of the immune system.
The treatment is autologous, meaning it is sourced from and administered to the same individual, which minimizes risks associated with donated substances. The specific combination of highly concentrated platelets alongside a significant number of leukocytes is what distinguishes LR-PRP from other blood-derived therapies.
Composition and Preparation of LR-PRP
The creation of LR-PRP begins with a standard blood draw. This whole blood contains red blood cells, white blood cells (leukocytes), platelets, and plasma, the liquid matrix that holds everything together. The goal of the preparation process is to isolate and concentrate the platelets and leukocytes from the other components.
This separation is accomplished through centrifugation, where a machine spins the tube of blood at high speeds. This rapid spinning uses force to separate the blood components into distinct layers based on their density, with the red blood cells settling at the bottom.
Above the red blood cells, a thin, whitish layer forms, known as the “buffy coat.” This layer is dense with both platelets and the majority of the blood’s leukocytes. To create LR-PRP, the buffy coat is carefully extracted and sometimes resuspended in a small amount of plasma, creating the final product.
Distinguishing Leukocyte-Rich from Leukocyte-Poor PRP
The primary difference between Leukocyte-Rich (LR-PRP) and Leukocyte-Poor (LP-PRP) preparations is the concentration of white blood cells. While both therapies utilize a high concentration of platelets, LR-PRP processing is designed to retain the leukocyte-dense buffy coat. In contrast, LP-PRP preparation involves techniques to remove most white blood cells, resulting in a product that is primarily concentrated platelets in plasma.
This difference in cellular makeup has functional implications. The high number of leukocytes in LR-PRP, particularly neutrophils and macrophages, introduces a strong pro-inflammatory element to the therapy. These white blood cells initiate an inflammatory response, which is a natural part of the body’s healing cascade and can be useful for clearing out damaged tissue.
Conversely, LP-PRP is formulated to deliver growth factors from platelets with minimal associated inflammation. The goal is to stimulate tissue repair without triggering a significant inflammatory reaction. This makes it suitable for applications where inflammation might be undesirable, such as within a joint space. The choice between LR-PRP and LP-PRP is a clinical decision based on the specific condition and the desired biological response.
Therapeutic Applications and Target Tissues
LR-PRP is utilized in orthopedics and sports medicine to treat chronic injuries, particularly those involving tendons. Conditions like lateral epicondylitis, commonly known as “tennis elbow,” and patellar tendinopathy, or “jumper’s knee,” are common targets. These are often chronic conditions where the natural healing process has stalled, leaving the tissue in a state of disrepair.
The pro-inflammatory nature of LR-PRP is considered an advantage in these contexts. Injecting a substance with a high concentration of leukocytes is intended to disrupt the chronic, stagnant state of the injured tissue. The resulting acute inflammatory response is thought to effectively “restart” the healing process by clearing out degenerated tissue and signaling the body to initiate a more robust repair sequence.
Beyond tendons, LR-PRP is also explored for certain cases of osteoarthritis. While the use of PRP in joints is often associated with leukocyte-poor formulations to avoid inflammation, some evidence suggests LR-PRP may offer benefits in specific situations. The rationale is that the inflammatory mediators can help modulate the joint environment and stimulate cellular activity.
Biological Mechanism of Action
The therapeutic effects of LR-PRP are driven by the combined actions of its two main components: platelets and leukocytes. Once injected into the target tissue, the concentrated platelets become activated and degranulate, releasing growth factors. These signaling proteins, including Platelet-Derived Growth Factor (PDGF) and Vascular Endothelial Growth Factor (VEGF), communicate with local cells, encouraging them to begin tissue repair and regeneration.
Simultaneously, the high concentration of leukocytes initiates a controlled inflammatory cascade. These white blood cells release their own set of signaling molecules called cytokines. This action helps to break down and remove damaged or fibrotic tissue, a process known as catabolism, and can provide an antimicrobial effect, reducing the risk of infection at the injection site.
This initial inflammatory phase, while potentially causing temporary discomfort, is a planned part of the mechanism. Following this phase, the leukocytes, particularly macrophages, can switch to an anti-inflammatory and pro-reparative state. This dual-phase action—an initial inflammatory cleanup followed by a platelet-driven rebuilding process—is how LR-PRP is believed to turn a chronic, non-healing injury into one that is actively undergoing repair.