Title: IL-1β-pre-conditioned mesenchymal stem/stromal cells’ secretome modulates the inflammatory response and aggrecan deposition in intervertebral disc

Authors: JR Ferreira, GQ Teixeira, E Neto, C Ribeiro-Machado, AM Silva, J Caldeira, C Leite Pereira, S Bidarra, AF Maia, M Lamghari, MA Barbosa, RM Gonçalves

Address: I3S – Rua Alfredo Allen 208, 4200-135 Porto, Portugal

E-mail: raquelg at ineb.up.pt

Abstract: Mesenchymal stem/stromal cells (MSCs) have been increasingly used in clinical trials for low-back pain (LBP) and intervertebral disc (IVD) degeneration with promising results. Their action mechanisms are not fully understood, but they reduce IVD pro-inflammatory markers in a pro-inflammatory/degenerative IVD microenvironment. In this study the therapeutic potential of the MSC secretome, as an alternative cell-free approach for treating degenerated IVDs, was examined. Human bone marrow-derived MSC secretome (MSCsec) was collected after 48 h of preconditioning in IL-1β (10 ng/mL) and low oxygen (6 % O2), mimicking the degenerative IVD. IL-1β-pre-conditioning of MSCs increased secretion of pro-inflammatory markers hIL-6, hIL-8, hMCP-1, etc. The therapeutic effect of MSCsec was tested in a pro-inflammatory/degenerative IVD ex vivo model. MSCsec down-regulated IVD gene expression of pro-inflammatory cytokines (bIL-6, bIL-8) and matrix degrading enzyme bMMP1, while bMMP3 and bTIMP2 were up-regulated, at 48 h. After 14 d, MSCsec-treated IVDs revealed increased aggrecan deposition, although no differences in other ECM components were observed. Protein analysis of the MSCsec-treated IVD supernatant revealed a significant increase of CXCL1, MCP-1, MIP-3α, IL-6, IL-8 and GRO α/β/γ (related to TNF, NOD-like receptor and neutrophil chemotaxis signalling), and a decrease of IFN-γ, IL-10, IL-4, IL-5 and TNF-α (associated with T-cell receptor signalling). MSCsec-treated IVD supernatants did not promote angiogenesis and neurogenesis in vitro. Overall, MSCsec can be a safe therapeutic approach, presenting a strong immunomodulatory role in degenerated IVD while potentiating aggrecan deposition, which can open new perspectives on the use of MSCsec as a cell-based/ cell-free therapeutic approach to LBP.

Key Words: Mesenchymal stem cells, degenerative intervertebral discs, immunomodulation, secretome, paracrine signalling, extracellular matrix.

Publication date: April 20th 2021

Article download: Pages 431-453 (PDF file)
DOI: 10.22203/eCM.v041a28