What is PRP? This term, which is the abbreviation of the words “Platelet Rich Plasma”. Platelets, also known as thrombocytes, are one of the important factors that ensure blood clotting. In the 1970s, plasma containing a large amount of platelets was prepared for the treatment of a disease called “thrombocytopenia” and started to be used for therapeutic purposes. In the 1980s, the solid version of the same solution began to be used in maxillofacial surgery under the name of PRF (Platelet Rich Fibrin). Initially, it was noticed that this mixture, which was used only to correct bleeding disorders, also facilitated the proliferation of cells, and it has been widely used in dermatology for the purpose of aesthetically beautifying the skin. Its use by sports physicians in the treatment of injured athletes has made PRP popular. Because the athletes’ close relationship with the media has increased the interest in this treatment. With the demonstration that PRP is beneficial in the treatment of chronic (long-term non-healing) wounds over time, it has started to be used in the branches of cardiac surgery, pediatric surgery, urology, gynecology, plastic surgery and eye diseases. Biology of platelets Platelets, like other blood cells, are produced in the bone marrow. They are very small structures in the form of a disk. Its number in healthy people varies between 150.000 and 450.000 per microliter (cubic millimeter). Each platelet contains granules ranging from 50 to 80. Functions of platelets Their main function is to create a clot to stop bleeding. When there is an injury in the vessel, the platelets begin to adhere here, become active and form a lump by piling up on each other. The granules inside the activated platelets secrete various factors. Platelets have other functions besides clot formation. The granules secrete a large number of growth factors (Growth Factor – GF) and cytokines. Cytokines enable certain cells to become active and reproduce. These cells, to which they are attached, also perform different tasks. Growth factors and cytokines provide the formation of inflammation. Inflammation is an important step in wound healing. At the same time, the proliferation of cells, the formation of new vessels, and the collection of stem cells here are provided. We can also consider platelets as structures that ring the alarm bell for the initiation of some curative events. Preparation of PRP After taking the blood with an injector from a person, PRP is prepared in 3 stages: Prevention of clotting Centrifuge Activating the solution Inhibition of clotting (anticoagulation) The blood taken from the vein coagulates spontaneously after a while and its structure changes completely. If the coagulation of the taken blood is not prevented, the platelets become active, break down and the substances in them spread to the environment, forming a clot and completing their task. After that, it is not possible to use the cells in the blood for special purposes. For this reason, the blood taken from the vein is put into a tube containing a chemical that prevents clotting. The blood, which has lost its coagulation feature, contains all the necessary substances and of course platelets in normal quantities. Centrifuge The tube with the blood inside is placed in a centrifuge machine and rotated at a certain speed for a certain time. During this rotation, depending on the centrifugal force, the elements in the blood are clustered in different layers according to their specific gravity. Red blood cells are collected at the bottom of the tube. Platelets and white blood cells (leukocytes) are collected in the layer above it. In the uppermost layer, there is only plasma. The part called PRP and used is the yellowish layer in the middle. In order to increase the volume, this yellowish layer and the plasma layer above it can be mixed with each other at different rates. The yellowish layer in the middle can be centrifuged once again to separate the leukocytes and platelets. Activation Platelets in PRP are not active. That is, they are in their natural state in the circulating blood. Platelets must be activated in order to start their function. Under normal conditions, when an injury occurs, the edges of the wound (wall of the injured vessels) activate platelets automatically. However, there are two different views for the platelets in the PRP prepared outside to become active and start working. According to one view, after the PRP solution is injected into the tissue, it is automatically activated by the surrounding tissues and no outside intervention is required. According to another view, the activation process should be applied before the PRP is injected.  In order to activate the platelets, the chemicals previously used as an anticoagulant must be removed. At the beginning of the list of the materials which are used for this purpose there are chemicals containing calcium (such as calcium chloride). In addition, substances called calcium gluconate and thrombin can be used for platelet activation. No matter what substance is used, 10 minutes after the platelets become activated and the biologically active proteins they contain begin to be released. Therefore, activated PRP should be used within 10 minutes at the latest. Unactivated PRP can remain intact for up to 8 hours. Ideal density There is no consensus on what the platelet count should be in the PRP solution. According to the PRP preparation used in the clinic, it may contain two to nine times more platelets than its blood level. Studies have not been able to establish a link between excess platelet count and effectiveness. Areas where PRP is used PRP, which is used in almost every field of medicine, is mainly used for the following purposes in plastic surgery: Skin rejuvenation and refreshment PRP, which is given under the skin or into the skin, provides the formation of new vessels in the region thanks to the secreted active proteins. It stimulates the skin and subcutaneous cells, causing them to function better. With the release of new collagen, it increases the elastic properties of the skin and makes it tighten. It also makes it easier for stem cells to come here. Reducing  burn and other scars and skin disfigurements PRP makes healed scars and burns less noticeable. For this, the solution is given into and just below the scar. It is widely used to reduce acne scars on the face, but the success rate varies a lot. It can be useful in cases that cause discoloration of the skin (pigmentation disorders). Increasing permanence in fat injection The biggest problem of fat injections is that only a part of the given adipose tissue is retained and the rest is absorbed. As a result, fat injections need to be repeated at intervals of a few months. It has been shown that if PRP is added to the injected fat the survival rate is significantly higher. The ratio of PRP to be mixed into the adipose tissue to be administered is also important. Although the 0.5/1 ratio seems to be ideal, on the other hand it is clear that considering very high amounts of fat (sometimes more than one liter) are given in breast augmentation or buttock augmentation, it is impossible to obtain PRP at this ratio. Hair loss (baldness) treatment The hairy regions are the areas where the effects of PRP can be best observed. Because here it is easy to determine the number and shape of the hair with objective methods. There is a tight communication between the hair follicles and the papilla cells in the skin. PRP multiplies dermal papilla cells. The increased number of papilla cells strengthens the hair growth phase in the hair follicle and prolongs its duration. It also allows the formation of new hair follicles. The hair loss phase is shortened and the hair growth phase is lengthened and more dense hair can be formed. In addition, it has also been shown that if the hair follicles are transplanted after being dipped and removed into the PRP solution before the transplantation the survival rate of these follicles increases between 5 and 9 times. Treatment of non-healing (chronic) wounds It is a well-known fact that the wounds in some areas do not heal in patients with atherosclerosis, diabetes and patients who have received radiation therapy. In this case, successful results are obtained with PRP injected into the wound. How it is applied PRP can be used in different ways depending on the purpose and the area to be applied: Direct injection PRP is most easily used by injecting it into the area with an injector and a fine needle. This method is ideal in the treatment of baldness, scar treatment, and chronic wounds. Direct application on skin or wound The solution can also be used on the skin, but in this case, micro-injury is created on the skin surface to facilitate absorption of the solution into the inner parts. The easiest method for this is the micro needling method. Cylinders containing very small needles are run over the skin and micro-injuries are created in this way. The PRP applied on them penetrates into the skin and performs the task expected from it. After laser treatment on the skin, PRP solution can be applied on it. Laser therapy and PRP It has been observed that applying PRP injection to the same area immediately after applying laser treatment to the skin for various purposes increases the effect of laser application. Complications and side effects PRP is a safe product as it is prepared from the person’s own blood. However, it is essential to work in a microbe clear (sterile) environment during preparation and administration. No serious complications are known and its known side effects are temporary conditions such as mild edema, redness and bruising in the given areas. Conclusion PRP is used increasingly, especially in cosmetic procedures, for tissue regeneration and rejuvenation. However, there is no consensus on how it should be prepared and how much and how often it should be given.