Human mesenchymal stromal cells from different tissues exhibit unique responses to different inflammatory stimuli

Abstract

Background

Mesenchymal stromal cell (MSC) - based therapies are emerging as promising treatment of various autoimmune diseases, however the utility of different MSC tissue sources remains elusive. We aimed to characterize MSC from different origins, namely bone marrow (BM), adipose tissue (AT) and umbilical cord (UC) and determine their functional effects on normal human lung fibroblasts (NHLF).

Methods

BM-, AT- or UC-MSC were isolated each from 3 different healthy donors. The gene expression and protein secretion were analyzed at basal level, along with TNFα-, IL-1β- and SAA- stimulated cells using real-time PCR and Luminex technology. Effect of conditioned medium (CM) from different MSC sources on migration was determined with wound scratch assay, while mitotic and apoptotic rates were studied using immunofluorescence microscopy.

Results

BM-MSC expressed highest basal mRNA levels of SDF1 and VCAM-1, while other genes were similarly expressed between MSC origins. TNFα priming of AT-MSC gained a prominent increase in IDO1 and CCL5 gene expression, with 928-fold and 4396-fold changes, respectively. Among all tissue sources, basal UC-MSC released highest protein levels of most measured analytes, including IL-6, IL-8, MCP-1, ICAM1, HGF, MMP1 and CH3L1. BM- and AT-MSC derived CM enhanced wound closure in NHLF, while an opposite effect was observed with UC-MSC derived CM. Our data also suggests that MSC-CM could contribute to decreased mitotic potential and increased apoptotic rate in lung fibroblasts.

Conclusions

Our study highlights origin-specific MSC profile differences and emphasizes a heterogenic response of different MSC to inflammatory stimuli.

Introduction

Mesenchymal stromal cells (MSC) are adherent cells of fibroblastoid appearance, with certain surface marker phenotype, that can be induced to various mesodermal phenotypes [[1], [2], [3]]. Properties of MSC, such as secretion of soluble bioactive factors capable of stimulating recovery of injured cells and their anti-inflammatory/immunomodulatory functions have led to clinical interest as potential therapeutic utility for a variety of indications in over 950 clinical trials [1,2].

MSC cells have been isolated from a wide variety of adult and fetal tissues [4], with bone marrow (BM-MSC), adipose tissue (AT-MSC), and umbilical cord (UC-MSC) currently representing the most commonly used tissue sources for MSC therapy [5]. The immunoregulatory properties and the tissue reparative functions of MSC may be induced or potentiated by inflammatory cytokines at damaged tissue sites [6]. Therefore, pre-treatment modification of MSC with cytokines or drugs may improve their efficiency in clinical use [5]. Inflammatory cytokines most frequently utilized for MSC activation are IFN-γ, TNFα, IL-1β; however, different cytokine combinations can produce different effects [7]. After stimulation at the damaged tissue sites, the newly immigrated MSCs release a plethora of cytokines, immunosuppressive factors, growth factors and adhesion molecules [6]. These factors then orchestrate local tissue/cell responses to promote tissue regeneration and repair.

There are individual studies accessible comparing different cytokine stimulation effects [8,9], however, comparative studies of MSC secretion profiles gathered from different organ origin sites with distinct cytokine stimulations are currently lacking. Here, we aim to investigate whether the MSC’s origin (bone marrow, adipose tissue and umbilical cord) would affect its transcriptome and secretome at baseline and after stimulation with proinflammatory mediators (TNFα, IL-1β and SAA). Additionally, we aimed to explore whether such differences would be reflected in the functional effects of MSC-conditioned medium (CM) on migration, proliferation and apoptosis of normal human lung fibroblasts (NHLF). These results could shed light on a more suitable cell/molecular source selection for better clinical utility of MSCs.