Studies on platelet rich plasma - new editorial policy for “Platelets”

In the last few years, there has been a significant increase in the number of manuscript submissions related to Platelet-Rich Plasma (PRP) to Platelets. PRP preparations are normally prepared from fresh autologous whole blood and usually contain a high concentration of platelets [1]. As platelets are of course vital for normal wound healing then this type of therapy could theoretically augment tissue healing with a wide number of potential clinical applications [2]. PRP is therefore gaining an increased profile in both scientific and popular media in many areas of regenerative medicine. For example, many high profile sports stars have been routinely treated with PRP in an attempt to improve tissue regeneration in a variety of injuries [3,4]. However, although many in vitro studies support the theoretical potential of PRP in tissue regeneration [5], the in vivo evidence is rather more inconclusive [6]. Despite efforts to improve standardization, there are also few large well controlled randomized clinical trials and the preparation, quality and contents of many platelet preparations in many studies are sometimes not fully defined [7–10]. Given the growth of interest, a number of commercial devices are also increasingly available for preparing sterile PRP for clinical therapies. As these devices often use different separation principles, the resulting PRP preparations are not standardized across different devices and therefore exhibit varying quantities, purity and quality of the platelets obtained [11]. For example, many products often contain plasma but may sometimes also contain both white and red cells. PRP preparations may also be activated via a variety of methods prior to clinical use and therefore can contain fibrin and released platelet granular proteins which are of course important for their biological efficacy in wound healing. Some bioactive proteins or factors can also have opposing inhibitory effects on the cellular regenerative cascade. Defining the cellular and bioactive factor contents of different PRP preparations is therefore essential to understand the variables associated with the potential biological activity/efficacy of PRP preparations [7]. A recent large (N = 230) randomized controlled trial (PATH-2) has recently demonstrated that a standardized Leukocyte Rich PRP (L-PRP) is not effective over placebo for improving the healing of Achilles Tendon Healing [12]. This study has clearly set a standard in the field and also demonstrated the importance of monitoring the quality control of the PRP given to individual patients. Although the trial demonstrated that PRP did not enhance healing or quality of life over placebo, we demonstrated that the majority of patients in the treatment arm received an optimal L-PRP standardized preparation containing a high concentration of platelets and expected growth factor contents. Although there was still some significant variability of the cellular and protein content between all the PRP preparations this had no impact upon individual tendon healing.

New Editorial Policy

Below, we outline the editorial policy in Platelets for the minimum requirements for future manuscripts that include PRP and related products as their major focus. All future submitted manuscripts on PRP utilized within both in vitro and in vivo settings (animal or human) should fully define the characteristics of the preparations used including:-

1. The source of blood or platelets whether autologous or allogeneic.

2. The anticoagulant, volume and age of blood used to prepare PRP.

3. The method used to prepare PRP.

4. The centrifugation conditions (g value, temperature and time) used in the laboratory or within commercial PRP preparation devices.

5. If a commercial preparation device is used then include the make and batch numbers/expiry dates of disposables used to prepare the PRP.

6. A full description of how the PRP is harvested (e.g. from buffy coats or PRP supernatants).

7. A measurement of the cellular content of the original whole blood and derived PRP including platelet count, white cell counts and red blood cell counts and the methods used to count the cells.

8. The concentration factor and yield of platelets obtained.

9. A measure of quality of the PRP preparation (e.g. cellular content, platelet activation status, platelet specific proteins and growth factor content).

10. Whether the PRP is activated prior to application either in vitro or in vivo, including the method used to activate the platelets before use and whether this converts plasma fibrinogen to form fibrin rich clots.

11. The method and number of in vivo applications, the specific delivery sites and volume of PRP administered,

In summary by ensuring that all these variables are included in all future papers will not only improve standardization but facilitate better comparisons to be made between studies. In vivo studies and trials should ideally also be appropriately controlled and adequately powered, but also take into account the content and quality control of the platelet preparations to ensure that clear correlations between the products and outcomes are established.

Declaration of Interest

The authors have no relevant conflict of interest to disclose