Platelet-rich plasma
Platelet rich plasma ( platelet-rich plasma or PRP also ) is produced by plasmapheresis with an autotransfusion device or a special table unit of autologous patient whole blood. The separation principle is based on centrifugal force, arrange through which the individual blood components due to their different specific weight in layers and can then be collected separately ( plasmapheresis ). The whole blood is in this case in the components of red blood cells, platelet-poor plasma (PPP) and platelet -rich plasma separated (→ blood plasma). In a second step can be made from the separated PRP a thrombinreiches gel ( autologous Plättchengel, APG). This may in wound healing, and especially in chronic wounds play an important role. Another positive effect promises the method on postoperative bleeding and pain. When bleeding and platelet deficiency enriched for treatment serum ( platelet concentrate) from foreign donors ( allogeneic ) were used.
History
In the early 1960s, the possibility was described by Schulte to treat wound defects with autologous autologous blood. These first autologous blood and a few years later centrifuged autologous blood for filling of cysts was used. However, this work has been little international attention. It was not until about 1996 autologous blood products were re-used for hemostasis or as a tissue adhesive. 1997, there was the publication of a method for the preparation of PRP. In 1998, the first clinical trial evaluating the use of PRP to patients in oral surgery has been published.
PRP applies today, especially in the dental, oral and maxillofacial surgery, orthopedics, plastic surgery and in the treatment of diabetic wounds, but also in the cardiothoracic and vascular surgery. In many publications in these areas, it is, however, so that it is merely descriptions of individual cases or case series and represent only a few work a sound scientific investigation. Therefore, falls for this reason, the definition of the German Medical Association in accordance concise.
The preparation of PRP was performed in the 1990s, especially with devices for autotransfusion in complex steps. Today, standing alongside modern autotransfusion devices with semi-automatic programs, a number of desktop devices from different vendors are available, which allow the preparation of PRP with small amounts of blood. Their effectiveness in terms of the quality of the generated platelet rich plasma has also increased in comparison to the early days.
Production
The amount of blood to be taken is dependent upon the device used for plasmapheresis. It is, when using a table unit at about 20 to 100 ml of whole blood. For an autotransfusion device between 350 to 500 ml are needed. The instrument used depends on the amount of the required platelet-rich plasma. Small tabletop units found mainly in outpatient and minor surgery use (eg dentistry, plastic surgery, etc). Autotransfusion devices are used primarily for major surgery (eg, cardiac, thoracic and vascular surgery). With the amount of blood to be taken and the effort increases. The patient is a doctor after the method normovoläme acute hemodilution, control of blood pressure and the provision of volume and fluid replacement, taken from the blood. As can be seen from a desktop device with a syringe. For a larger amount of blood empty bags used in the clotting of the blood with citrate prevented. These are used for blood donation.
The whole blood is drawn and centrifuged to the patient. The supernatant plasma is separated depending on the method or centrifuged again. This achieves a 3 to 4 times the concentration of platelets in a small volume of plasma. The quantity produced by PRP is between a few milliliters at a desk-mounted and up to 50 milliliters with an autotransfusion device. This product must be used within eight hours. About centrifugal force and duration, there are different information.
It is one of the advantages of the method that is lost to the patient blood. Also in the removal of larger amounts after the plasmapheresis, the erythrocytes and the platelet-poor plasma retransfused (→ blood transfusion ), while the platelet rich plasma of the intended use is supplied.
Operation
Platelets contain a high content of various growth factors and cytokines, for example " platelet derived growth factor ", " Transforming Growth Factor - β1 and β2 ,", " epidermal growth factor " (EGF), " fibroblast growth factor ", " epithelial growth factor ", " insulin-like growth factors "and" platelet-derived angiogenesis factor ". Due to physiological or artificial induced platelet activation, these factors are released and have a chemotactic as well as directly and indirectly gewebsregenerativ. Mesenchymal stem cells and fibroblasts and mononuclear leukocytes are stimulated to proliferate and grown locally.
Some studies recommend to activate the platelets with different amounts of calcium chloride or thrombin ( → autologous Plättchengel, APG). Activation of platelets mainly makes sense if the wound healing is impaired for different reasons. Messengers may be due to microcirculatory disturbances will not get out of the wound area in the systemic circulation and bring healing in motion. Here are especially chronic wounds or large surgical wounds to call, in which an impaired wound healing is also expected.
Application
Indications from the human medicine, dentistry and veterinary medicine are manifold: poorly healing wounds, tendonitis, fracture treatment, slow bone regeneration, joint disease ( arthropathy ), keratitis, etc. Especially in the oral and maxillofacial surgery PRP is often used. But areas of application are also increasingly the cardiac, thoracic and vascular surgery where PRP is mainly used for the prophylaxis of wound healing disorders.
Terms of Use
The transfer ( transplant ) of platelet-rich plasma is considered to be the production of a pharmaceutical product where the attending physician or dentist has prepared it yourself. PRP is subject to the Transfusion Act ..