Coculture with monocytes/macrophages modulates osteogenic differentiation of adipose-derived mesenchymal stromal cells on poly(lactic-co-glycolic) acid/polycaprolactone scaffolds.

Hongbo Tang,Jeroen J.J.P Beucken,Yang Zhang,Johanna F.A Husch,Fang Yang,John A Jansen

doi:10.1002/term.2826

Abstract

The effects of immune cells, in particular macrophages, on the behaviour of mesenchymal stromal cells (MSCs) have recently gained much attention for MSCs‐based tissue‐engineered constructs. This study aimed to evaluate the effect of monocytes/macrophages on the osteogenic differentiation of adipose‐derived mesenchymal stromal cells (ADMSCs) in three‐dimensional (3D) cocultures. For this, we cocultured THP‐1 monocytes, M1 macrophages, or M2 macrophages with ADMSCs on 3D poly(lactic‐co‐glycolic) acid (PLGA)/polycaprolactone (PCL) scaffolds using osteogenic medium for up to 42 days. We found that osteogenic differentiation of ADMSCs was inhibited by monocytes and both macrophage subtypes in 3D scaffolds. Furthermore, coculture of monocytes/macrophages with ADMSCs resulted in downregulated secretion of oncostatin M (OSM) and bone morphogenetic protein 2 (BMP‐2) and inhibited expression of osteogenic markers alkaline phosphatase (ALP), bone sialoprotein (BSP), and runt‐related transcription factor 2 (RUNX2). Compared with both macrophage subtypes, monocytes inhibited osteogenic differentiation of ADMSCs more significantly. These data suggest that the mutual interactions between monocytes/macrophages and ADMSCs negatively affect MSC osteogenic differentiation and thus possibly bone healing capacity, which highlights the importance of the micro‐environment in influencing cell‐based constructs to treat bone defects and the potential to improve their performance by resolving the inflammation ahead of treatment.

Highlights

Inflammation is the first stage of bone healing after bone injury
We used 3D poly(lactic‐co‐glycolic) acid (PLGA)/PCL scaffolds and a direct coculture model to culture primary human adipose‐derived mesenchymal stromal cells (ADMSCs) with THP1 monocytes, M1 macrophages, or M2 macrophages in osteogenic medium with a monoculture of ADMSCs serving as control
Our findings indicate that the osteogenic differentiation of ADMSCs is inhibited by monocytes and different macrophage subtypes in 3D scaffolds

Summary

| INTRODUCTION

Inflammation is the first stage of bone healing after bone injury. The state of inflammation has been indicated to affect the delicate balance between bone formation and bone degradation (Loi et al, 2016). Standardized culture conditions have been established for most monocultures (American Type Culture Collection, 2018), coculture models require a justified choice for a specific medium This choice is based on the research question that favours behavioural analysis of the predominant cell type within the coculture, for example, vascular cells for angiogenic behaviour (Hofmann et al, 2008; Levenberg et al, 2005) and MSCs for osteogenic differentiation (Ma et al, 2011; Ma et al, 2014). It was found that PL can induce an anti‐inflammatory response of monocytes/ macrophages (Linke et al, 2017) These findings suggest the potential of using PL to culture human cells for the clinical usage. The objective of this study was to evaluate the effect of monocytes and macrophage subtypes on osteogenic differentiation of ADMSCs cultured on 3D PLGA/PCL scaffolds using a direct coculture model. We hypothesized that monocytes and macrophage subtypes would differentially affect the osteogenic differentiation of ADMSCs compared with ADMSCs monocultures on PLGA/PCL scaffolds

| MATERIALS AND METHODS

| RESULTS

Findings

| DISCUSSION