PRP: Q&A | Wounds Africa

PRP in wound care: Q & A

Main Principles

If platelets are concentrated and placed in a wound, this will usually accelerate the healing process.
Platelet concentrate is primarily used in wounds that do not heal with conventional treatment, or in wounds with exposed bone or tendon.
When producing platelet concentrate, the patient’s own blood is used (autologous blood).
Platelets are perishable and should ideally be used within one hour after preparation.
We recommend using ready-made kits available for purchase to prepare the concentrate. In a low-resource setting, however, it is possible to make a PRP product for wound care without any special kit.
While platelets are almost magical, they do not always perform magic. In other words, the treatment will not always work as expected. Often, this is because the wound bed is not properly prepared and not ready for PRP treatment.
Often, repeated PRP treatments are needed (for example, weekly) to achieve the best results.
PRP is not the same as stem cell treatment.

Where do platelets come from, and what do they do in the body?

When we think about blood cells, we usually think first of red blood cells, which transport oxygen, and white blood cells, which make up the most important part of our immune system. We often forget about the blood platelets (thrombocytes).

Figure 1 Electron micrograph of the most common blood cells (the image has been colorized). On the left is a red blood cell (an erythrocyte), in the center a platelet (a thrombocyte), and on the right a white blood cell (a leukocyte). Copyright: commons.wikipedia.org

Platelets play an important role in the body, as they help repair injuries. This is most clearly seen when we cut our skin and a scab forms. Platelets help stop bleeding and are the cells that form the scab. Afterward, platelets release a number of growth factors that stimulate cells to close the defect.

There are many different growth factors. Some are important for building collagen, others stimulate bone repair after fractures, and still others promote the growth of skin over a wound. You can think of these growth factors as fertilizer. Some types of fertilizer are ideal for orchids, while roses thrive best with a different type. In the same way, different cells in the body respond best to different growth factors.

All blood cells are formed in the bone marrow from stem cells. Bone marrow may look unusual, but it is extremely important. It is truly remarkable that the body can produce so many different types of blood cells from the same type of stem cell.

Figure 2 Left: Bone marrow in the femur of a pig. Right: Stem cells in the bone marrow differentiate into many different types of blood cells, including platelets. Copyright: clinicalillustrations.net

Which Wounds May Benefit from Platelet Concentrate?

In principle, most wounds are expected to heal faster if platelet concentrate is added. However, when using a commercial kit to produce the concentrate, the treatment is not inexpensive. Treating a wound with platelet concentrate using a commercial kit often costs between 150 and 300 US Dollars, so it is clear that this treatment should be reserved for wounds that truly require it.

The following are good indications for the use of platelet concentrate:

Wounds that have not responded to other adequate treatments
Wounds with minor areas of exposed bone or exposed tendon where other treatments have not been successful

When used for the right indication, platelet concentrate can actually be cost-saving. In some cases, it may even be the most economical treatment option. For example, if a wound fails to heal and the patient requires home nursing services for dressing changes every 3 days for several months, the use of platelet concentrate may be financially beneficial compared with the cumulative personnel costs.

For platelets to attach effectively within the wound, it is essential that the wound has been thoroughly cleaned (debrided). Platelet concentrate will not be effective in wounds with significant necrosis or a high bacterial load. Platelets will also not function well if the wound produces excessive exudate, as they may simply be washed out of the wound.

If platelet therapy is planned, the wound often needs to be prepared for several weeks in advance, with frequent debridement and appropriate compression therapy, to optimize all conditions before the concentrate is applied.

There are no contraindications to the use of platelet concentrate. It is a very safe treatment. However, using it on a wound that does not require it, or on one that has not been properly cleaned, is a waste of resources.

Figure 4 Severe defect in the left forefoot following amputation of the great toe in a patient with a diabetic foot ulcer and impaired arterial circulation. There is open contact with the underlying bone. We were initially considering a below-knee amputation. The patient received two treatments using the GPS III system over a two-week period. The middle image shows the coagulated PRP clot ready to be placed into the wound. The image on the right shows the wound after four weeks. The wound subsequently healed without complications.

Figure 5 Wound between the 4th and 5th toes on the right foot in a patient with a diabetic foot ulcer. There is contact with bone, and the wound has shown no signs of healing despite standard treatment measures and offloading. After one treatment with the GPS® III system, the wound healed within six weeks.

Figure 6 Postoperative wound following osteosynthesis of a high-energy injury to the right forearm. After three weeks, the patient still had a skin defect with an opening down to the plate. After treatment with platelet concentrate (GPS® III), a clot formed in the wound. The concentrate appears somewhat darker than is usually seen when platelet concentrate is used, but the wound healed rapidly afterward and was almost closed after 17 days. Copyright: Haukeland University Hospital.

Video 1: PRP is most often applied topically to the wound, meaning it is placed directly on the wound bed. Some clinicians, however, inject PRP into the tissue beneath the wound. The intention is to stimulate the tissue below the wound bed to initiate healing. We have only used this method to a limited extent ourselves and usually prefer the topical approach.

In this video, the use of subcutaneous PRP injection is demonstrated in a presumed venous ulcer. It can be debated whether PRP should be the primary treatment in this case, and whether treatment of the insufficient veins might be more appropriate. However, we include the video here to illustrate the principle.

How Is Platelet Concentrate Produced?

To produce platelet concentrate, some equipment is required. We recommend using commercially available, ready-made kits to ensure predictable, reliable results (see also the next section).

In simple terms, about 50 ml of blood is drawn from the patient into a vial containing citrate or another substance that prevents clotting. The blood mixed with citrate is then centrifuged at high speed ( about 3200 rpm) for about 10 minutes.

After centrifugation, the blood separates into three layers:

At the top is plasma, which contains very few blood cells.
In the middle is a thin layer known as the “buffy coat.” This layer contains a high concentration of platelets. It also includes some white blood cells, red blood cells, and plasma, but the key feature of this layer is the high platelet concentration.
The bottom layer mainly contains red blood cells.

The buffy coat layer is then aspirated. A substance (for example, calcium gluconate) is subsequently added to neutralize the citrate, allowing platelets to aggregate. This process forms a gel-like clot, which can then be placed directly into the wound.

All available commercial kits use their own patented technology for separating and collecting platelets during centrifugation.

Figure 7: When blood is centrifuged at high speed (for example, 3200 revolutions per minute) for approximately 10 minutes, it separates into three layers. The middle layer is often called the “buffy coat,” and it contains the highest concentration of platelets. Copyright: commons.wikipedia.org

Are all commercial PRP products similar?

The answer is NO! All PRP products derived from commercial kits differ in consistency, the number of platelets they concentrate, and the amount of leukocytes they contain. The only common denominator for all these products is that each company will try to convince you that their method of concentrating PRP is better than the competitors'.

When using PRP for joint injections to treat arthritis or for injections under the skin for cosmetic reasons, it is desirable to make an LP-PRP ( Leukocyte-poor PRP) product that contains as many platelets as possible, but with a low number of leukocytes. This is because leukocytes can induce inflammation, which we do not want in our joints or under our skin. However, even though many may think that inflammation in a wound is a "bad thing", inducing a controlled, slight inflammation by introducing leukocytes to the wound bed is actually a positive thing. In other words, the ideal PRP for treating wounds should include as many platelets as possible and also a fair number of leukocytes: LR-PRP (Leukocyte-rich PRP). Our favorite PRP system for many years was the Zimmer Biomet GPS III system - it had the desired combination of high platelet concentration and the right amount of white blood cells. In our hands, it performed excellently in many cases. Sadly, the commercial kit was discontinued and is no longer available.

Table 1. Comparative overview of the characteristics of common commercial PRP systems. It is clear that there are significant differences between the contents and characteristics of the end product. This makes it difficult to compare results from studies using different systems. As a general rule of thumb, when treating hard-to-heal wounds, a system providing a high platelet concentration and a high leukocyte count is considered advantageous.

Gjennom de siste årene har vi funnet ut at resultatene blir enda bedre om en får blodplatene til å koagulere seg i såret istedenfor å danne en geleklump først som så legges i såret. Vår teori er at blodplatene fester seg bedre i såret om de får mulighet til å koagulere først når de er kommet i kontakt med såret.

Trombocyttkonsentrat er ferskvare. En anbefaler at blodplatene er tilført såret helst innen en halvtime etter de er tatt ut av sentrifugen, senest innen en time etterpå.

Do All Patients Have Platelets of the Same Quality?

In theory, one might assume that platelets from a young, healthy patient are more vital and active than those from a 90-year-old patient. That said, we have also observed good results in elderly patients. After more than 25 years of experience using platelet concentrate, we find it difficult to predict which patients will respond well and which will not. As a rule of thumb, however, PRP from a teenager usually induces a much faster healing response in a wound than PRP from a geriatric patient.

In our opinion, the most important factor is that the wound is thoroughly cleaned and has a low bacterial load before platelet concentrate is applied.

Several medications affect platelet function. The most common are NSAIDs (such as ibuprofen, naproxen, and diclofenac), acetylsalicylic acid, and all other anticoagulants like NOAK and Warfarin.

In our practice, we have not routinely required patients to discontinue these medications before treatment with platelet concentrate, and we have generally not observed poorer results in patients using anticoagulation. In particular, when using the newer 3C Patch system, anticoagulant medications are usually not a significant issue. However, it will usually take 2-3 times longer for a PRP clot to form when the patient is on stronger anticoagulation medication. When using systems from Regenlab or Zimmer Biomet, it is often necessary to add more of the component that induces platelet coagulation when the patient is taking anticoagulant medication.

Do All Patients Have Platelets of the Same Quality?

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