Biologic Adjuvants to Rotator Cuff Repairs Induce Anti-Inflammatory Macrophage 2 Polarization and Reduce Inflammatory Macrophage 1 Polarization In Vitro

Benjamin C Hawthorne; Sam Engel; Mary Beth R McCarthy; Mark C Cote; Augustus D Mazzocca; Katherine J Coyner

doi:10.1016/j.arthro.2024.04.031

Biologic Adjuvants to Rotator Cuff Repairs Induce Anti-Inflammatory Macrophage 2 Polarization and Reduce Inflammatory Macrophage 1 Polarization In Vitro

Arthroscopy. 2024 May 10:S0749-8063(24)00337-2. doi: 10.1016/j.arthro.2024.04.031. Online ahead of print.

Authors

Benjamin C Hawthorne¹, Sam Engel¹, Mary Beth R McCarthy², Mark C Cote², Augustus D Mazzocca², Katherine J Coyner³

Affiliations

¹ Department of Orthopaedic Surgery, UConn Health, Farmington, CT.
² Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, MA.
³ Department of Orthopaedic Surgery, UConn Health, Farmington, CT. Electronic address: coyner@uchc.edu.

PMID: 38735413
DOI: 10.1016/j.arthro.2024.04.031

Abstract

Purpose: To examine the effect of various biologic adjuvants on the polarization of macrophages in an in vitro model for rotator cuff tears.

Methods: Tissue was harvested from 6 patients undergoing arthroscopic rotator cuff repair. An in vitro model of the supraspinatus and subacromial bursa was created and treated with control, platelet rich plasma (PRP), autologous activated serum (AAS), or a combination of PRP+AAS. The effect of treatment on macrophage polarization between M1 pro-inflammatory macrophages or M2 anti-inflammatory macrophages was measured using gene expression, protein expression, flow cytometry and nitric oxide (NO) production.

Results: Tendon and bursa treated with PRP, AAS and PRP+AAS significantly decreased the gene expression of M1 markers IL-12 and TNF-a, while significantly increasing the expression of M2 markers Arginase, IL-10 and TGF-b (p<0.05) compared to treatment with control. ELISA analysis of protein production demonstrated that compared to control, co-culture treated with PRP, AAS and PRP+AAS significantly decreased markers of M1-macrophages (IL-6, IL-12, and TNF-a), while significantly increasing the expression of markers of M2-macrophages (Arginase, IL-10, and TGF-b) (p<0.05). Flow cytometry analysis of surface markers demonstrated that compared to control, tendon and bursa treated with PRP, AAS and PRP+AAS significantly decreased markers of M1-macrophages (CD80, CD86, CD64, CD16), while significantly increasing the expression of markers of M2-macrophages (CD163 and CD206) (p<0.05). Treatment of the co-culture with PRP, AAS and PRP+AAS consistently demonstrated a decrease in NO production (p<0.05) compared to control. AAS and PRP+AAS demonstrated an increased macrophage shift to M2 compared to PRP alone, whereas there was not as uniform of a shift when comparing PRP+AAS to AAS alone.

Conclusions: In an in vitro model of rotator cuff tears, the treatment of supraspinatus tendon and subacromial bursa with PRP, AAS and PRP+AAS demonstrated an increase in markers of anti-inflammatory M2-macrophages and a concomitant decrease in markers of pro-inflammatory M1-macrophages. AAS and PRP+AAS contributed to a large shift to macrophage polarization to the anti-inflammatory M2 compared to PRP.