Leukocyte-Reduced Platelet-Rich Plasma Normalizes Matrix Metabolism in Torn Human Rotator Cuff Tendons

Abstract

Background:

The optimal platelet-rich plasma (PRP) for treatment of supraspinatus tendinopathy has not been determined.

Purpose:

To evaluate the effect of low- versus high-leukocyte concentrated PRP products on catabolic and anabolic mediators of matrix metabolism in diseased rotator cuff tendons.

Study Design:

Controlled laboratory study.

Methods:

Diseased supraspinatus tendons were treated with PRP made by use of 2 commercial systems: Arthrex Autologous Conditioned Plasma Double Syringe System (L^lo PRP) and Biomet GPS III Mini Platelet Concentrate System (L^hi PRP). Tendon explants were placed in 6-well plates and cultured in L^lo PRP, L^hi PRP, or control media (Dulbecco’s Modified Eagle Medium + 10% fetal bovine serum) for 96 hours. Tendons were processed for hematoxylin-eosin histologic results and were scored with the modified Bonar scale. Group 1 tendons were defined as moderate tendinopathy (Bonar score <3); group 2 tendons were assessed as severely affected (Bonar score = 3). Transforming growth factor β–1 (TGFβ-1), interleukin-1β (IL-1β), interleukin-1 receptor antagonist (IL-1Ra), interleukin-6 (IL-6), interleukin-8 (IL-8), and matrix metalloproteinase–9 (MMP-9) concentrations in PRP media were measured by use of enzyme-linked immunosorbent assay after 96 hours of culture with diseased tendon. Tendon messenger RNA expression of collagen type I (COL1A1), collagen type III (COL3A1), cartilage oligomeric matrix protein (COMP), MMP-9, MMP-13, and IL-1β was measured with real-time quantitative polymerase chain reaction.

Results:

Leukocytes and platelets were significantly more concentrated in L^hi PRP compared with L^lo PRP. Increased IL-1β was present in L^hi PRP after culture with group 1 tendons. IL-6 was increased in L^hi PRP after culture with group 2 tendons. Both TGFβ-1 and MMP-9 were increased in L^hi PRP after culture with either tendon group. In L^lo PRP cultures, IL-1Ra:IL-1β in PRP used as media and COL1A1:COL3A1 gene expression were increased for group 1 tendon cultures. Gene expression of MMP-9 and IL-1β was increased in group 2 tendons cultured in L^lo PRP. There was no significant difference in the expression of MMP-13 or COMP in either group of tendons cultured in L^lo PRP or L^hi PRP.

Conclusion:

L^lo PRP promotes normal collagen matrix synthesis and decreases cytokines associated with matrix degradation and inflammation to a greater extent than does L^hi PRP in moderately degenerative tendons. In severely degenerative tendons, neither PRP preparation enhanced matrix synthesis.

Clinical Relevance:

L^lo PRP may promote healing in moderately degenerative rotator cuff tendons.