A Method Of Preparing Platelet-Rich Plasma By Temperature-Control Without Exogenous Additives

Platelet-rich plasma(PRP)is autologous plasma with several times the normal platelet concentration.When activated,it can release high concentrations of various growth factors.These growth factors play an important role in promoting cell recruitment,proliferation and differentiation,generating extracellular matrix,collagen and new blood vessels,promoting hair follicle development and promoting hair growth.As PRP is rich in growth factors with the above functions,it has been widely used in orthopedic surgery,orthopaedic trauma,joint orthopedics,stomatology,dermatology,burns and other departments.Conventional PRP preparation methods do not have standard specifications,but there are similar steps to prepare PRP with different methods and devices.The first step is to mix anticoagulant to avoid blood coagulation,red blood cells and leukocytes will be removed by the first step of low-speed centrifugation.Then the appropriate amount of platelet-poor plasma will be removed after the second step of high-speed centrifugation.The last step is to add coagulant to activate platelets,so as to obtain a high concentration of various growth factors.However,the use of exogenous additives such as anticoagulants and activators may raise some concerns about the safety and effectiveness of PRP.In this paper,we propose a method to prepare PRP by temperature-controlled,called temperature-controlled PRP(t-PRP),which is without adding anticoagulants and accelerators.That is to say,the platelet should be enriched by two-step centrifugation method at 4 ?,then the platelet was activated by rewarming to 37?to obtain high concentration of growth factors.The conventional PRP(c-PRP)was used as the control.In the process of centrifugation for platelet enrichment,the boundary between the three layers of t-PRP was clearer,which was more conducive to the removal of red blood cells and white blood cells.The pH value of t-PRP was closer to the physiological conditions(pH=7.46?7.48),and the platelet concentration was 6.58±0.45 times of the whole blood,which was significantly higher than that of c-PRP(4.06+0.55 times).Histologically,the activation of t-PRP by rewarming at 37? was relatively slow,resulting in a uniformly distributed network of fibrin,which entrapped more platelets,and it is possible to integrate growth factors in the process of forming fibrin filaments.The content of growth factors in the activated t-PRP gel and its precipitated liquid showed that the t-PRP gel contained more growth factors and showed the characteristics of slow release of growth factors.In addition,t-PRP also has the same function as c-PRP,which can promote wound healing,and no additional activator is needed in this process.After contacting collagen in the tissue,t-PRP can gradually activate spontaneously,gelating and covering the wound.It indicates that in addition to its safety and effectiveness for clinical use,it can also be used in more diverse forms such as liquid smear,liquid injection and gel form cover.