Joint pathology and platelet-rich plasma therapies.

INTRODUCTION: At the beginning of the new millennium, there was a breakthrough in platelet-rich plasma (PRP) therapy for tissue repair. The mechanisms governing the effects of this therapy in joint pathology remain largely unexplored. AREAS COVERED: This review is primarily based on PubMed and Web of Knowledge searches with the terms osteoarthritis in combination with PRP, treatment, cartilage, synovium, platelets, inflammation and/or angiogenesis. This search was completed by a manual search for relevant studies. We mainly include papers from the last 5 years. The concept of dynamic reciprocity is used to shape understanding of the spatial relationship between cells and their microenvironments as well as between tissues within the joint. We describe the processes of joint injury and pathology relevant to the mechanism of action of PRP, and elaborate insights into how PRP components may influence inflammation, angiogenesis, cell death and cartilage chondroprotection. EXPERT OPINION: PRP therapies are more complicated than previously acknowledged, and an understanding of the fundamental processes and pivotal molecules involved will hopefully be elucidated soon. This challenge is to provide a comprehensive description of the relationship between PRP components, healing mechanisms and clinical outcomes. Although PRP therapies in clinical trials await assessment, they have shed light on new avenues of management because of their effects on repair functions.