Diversity among monocyte derived stromal cells

Abstract

Fibrocytes are monocyte-derived cells that morphologically look like fibroblasts, express both stromal and haematopoietic markers, and have been reported as being involved in wound healing and fibrosis. In-vitro derived fibrocytes can be differentiated in both serum-containing and serum-free environments and we wanted to study the relationship between these two fibrocytes; which potentially could be involved at different time points at a wound healing site. To investigate the relationship between serum-free and serum-containing derived fibrocytes monocytes were differentiated without serum. When these cells were placed in a serum-containing environment they became round, losing their fibroblast-like morphology. However when the reverse experiment was done on fibrocytes derived in a serum-containing environment there was no apparent effect on their morphology. The relationships between these two fibrocytes, as well as macrophages and fibroblasts was also examined using transcriptome analysis of 37000 genes, clustering the samples based on all the genes, and identifying those that were significantly different between the populations. This demonstrated that both fibrocyte populations are distinct from each other, as well as from both fibroblasts and macrophages. These data demonstrate that these two fibrocytes have different characteristics, suggesting that they may have different roles in the modulation of fibrosis in inflammation.