Platelet-Rich Plasma: My View from the Transfusion Service
Platelets play a significant role in primary hemostasis, however they also serve as a reservoir of a number of important growth factors, including but not limited to platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF). Thus, autologous platelets applied topically or injected into areas of recent surgical reconstruction or to wounds are thought to stimulate angiogenesis and aid in tissue repair and regeneration. Several instruments are available to harvest platelets, (re-suspended in plasma a.k.a. platelet-rich plasma (PRP)), and this provides a vehicle for delivery as a topical or injectable product.
There is no doubt that basic science and in vitro studies substantiate the release of platelet-derived growth factors and their potential role in healing, however robust trials and in vivo studies are lacking and often show conflicting results. The lack of strong clinical evidence is due to the marked heterogeneity of PRP preparations, platelet counts, and growth factor yields or activity. Differences in the site of use, type of injury and tissue, and patient comorbidities likewise contribute to the broad range of study results. Dosing regimens for optimal use are also unknown. There are no evidence-based studies of head-to-head comparisons of these products or their relative efficacies on patient outcomes. Current literature maintains that there is insufficient evidence to support the routine use of PRP in clinical practice. In spite of this, there continues to be extensive utilization of this product.
And I purposefully highlight the word product.
In my view, when allowing the use of instruments to acquire PRP, this represents manufacture of a blood product and constitutes a transfusion activity for which the Transfusion Service and specifically, the Transfusion Service Medical Director are ultimately responsible. All relevant transfusion activities fall under the auspice of the Transfusion Service and applicable standards would demand oversight of policies, processes and procedures. The AABB Standards for Blood Banks and Transfusion Services¹ clearly identify elements to be included such as equipment, suppliers, informed consent, document and record control, along with relevant quality and patient safety activities.
There are limited standards applicable to PRP specifically, such as storage temperature, expiration and conditions of use listed in the AABB Standards for Perioperative Autologous Blood Collection and Administration.² To this end, the International Cellular Medical Society,³ in 2011, noted a serious lack of guidelines surrounding the use of PRP and submitted a draft document which outlined elements for training, indications and contra-indications, informed consent, preparation, injection or application, safety issues and patient follow-up. A 2014 Cochrane Review called for standardization of PRP methods.
Overall, I would venture to say that few hospital Transfusion Services are aware of the scope of use of PRP within their facility(s). Regardless of one’s opinion of the current literature, I would urge all of us involved in transfusion practice to be informed of the use of PRP and to be vigilant in oversight of this activity. It is not merely a regulatory and accreditation issue, but our duty as laboratory physicians and clinical scientists to provide quality, safe and effective transfusion therapies for all patients. This will require educating our clinical colleagues and enabling them to understand our role in this critical process.
References and Suggested Reading:
- AABB Standards for Blood Banks and Transfusion Services, 29th edition, 2014
- AABB Standards for Perioperative Autologous Blood Collection and Administration, 5th edition, 2013
- Morae VY et al. Platelet-rich therapies for musculoskeletal soft tissue injuries. The Cochrane Library 2014
- Griffin XL et al. Platelet-rich therapies for long bone healing in adults. The Cochrane Library 2012
- Leitner GC et al. Platelet content and growth factor release in platelet-rich plasma: A comparison of four different systems. Vox Sang 2006; 91: 135-138
- Everts PA et al. Platelet-rich plasma and platelet gel: A review. J Extra Corpor Technol 2006; 38: 174-187
Author: Carolyn Burns, MD