Shift of EMT gradient in 3D spheroid MSCs for activation of mesenchymal niche function

Abstract

Despite the wide use of mesenchymal stromal cells (MSCs) for paracrine support in clinical trials, their variable and heterogeneous supporting activity pose major challenges. While three-dimensional (3D) MSC cultures are emerging as alternative approaches, key changes in cellular characteristics during 3D-spheroid formation remain unclear. Here, we show that MSCs in 3D spheroids undergo further progression towards the epithelial-mesenchymal transition (EMT), driven by upregulation of EMT-promoting microRNAs and suppression of EMT-inhibitory miRNAs. The shift of EMT in MSCs is associated with widespread histone modifications mimicking the epigenetic reprogramming towards enhanced chromatin dynamics and stem cell-like properties, but without changes in their surface phenotype. Notably, these molecular shifts towards EMT in 3D MSCs caused enhanced stem cell niche activity, resulting in higher stimulation of hematopoietic progenitor self-renewal and cancer stem cell metastasis. Moreover, miRNA-mediated induction of EMT in 2D MSCs were sufficient to mimic the enhanced niche activity of 3D spheroid MSCs. Thus, the molecular hierarchy in the EMT gradient among phenotypically indistinguishable MSCs revealed the previously unrecognized functional parameters in MSCs, and the EMT-enhanced “naïve” mesenchymal state represents an ‘activated mesenchymal niche’ in 3D spheroid MSCs.

The Adaptive Remodeling of Stem Cell Niche in Stimulated Bone Marrow Counteracts the Leukemic Niche

“…Accordingly, the BM microenvironment should undergo dynamic changes in niche activity to accommodate the alternating needs for hematopoietic activity. Consistent with this view, we have shown that the mesenchymal cells can undergo reversible changes during cell culture, exhibiting distinct niche activities [29], and that these niche activities are regulated by changes in signals from canonical Wnt or notch ligands, for example [17,30], as well as by the molecular gradient for the epithelial-mesenchymal transition (EMT), as observed in a model for 3-D mesenspheres [31]. However, the dynamic changes in the BM niche in response to varying physiological demands, which reveal how the regenerative process for maintaining body homeostasis is controlled, remains largely unknown.…”

Osteogenic potential of heterogeneous and CD271-enriched mesenchymal stromal cells cultured on apatite-wollastonite 3D scaffolds

“…This study reported a stronger osteogenic potential of CD271-MSCs than the PA-MSCs, but again was based on a 2D study. It is well documented that MSCs grown on 2D or 3D structural compositions have widely different properties [29][30][31], and here we demonstrate that, for our scaffold and cell populations, the differences between 2D and 3D culture can mean that results from 2D culture are a poor predictor of performance on a 3D scaffold. Interestingly, compared to uncultured CD271-enriched BM-MNCs, we observed a higher DNA content and higher ALP activity in native BM-MNCs (unselected and uncultured) when seeded on the A-W scaffold.…”

Mapping Structure and Biological Functions within Mesenchymal Bodies using Microfluidics

“…Human MSCs are known to constitute a heterogeneous population 8,9,10 . To examine the cellular diversity within the population, hMSCs were first characterized by their expression of membrane markers.…”

“…4! related to differentiation, immune-regulation and angiogenesis 8,9,10 . Nonetheless their aggregation leads to the formation of highly cohesive 3D spherical structures (which we designate hereafter as mesenchymal bodies, MBs) with improved biological activities in comparison to 2D cultures 11 .…”