Macrophage phenotypes modulate neoangiogenesis and fibroblast profiles in synovial-like organoid cultures

To investigate the interaction among the cells thought to be foundational to inflammation, fibrosis, and angiogenesis in the synovial membrane.

We encapsulated fibroblasts, polarized macrophages, and endothelial cells in a 3D culture system. We used this model to determine the cellular transcriptional profiles, cytokine secretion, and vascular formation associated with different macrophage phenotype conditions.

Neo-angiogenesis reached its maximum level at approximately day 21 in the presence of pro-inflammatory macrophages conditions, but was sustained in the presence of anti-inflammatory macrophages. RNA sequencing revealed an influence of macrophage phenotype on gene expression associated with fibrosis and angiogenesis. Furthermore, by including lipopolysaccharides-coated polyethylene particles (lcPE), an inflammatory stimulus replicating wear debris from joint replacements into our system, insights into the local reaction to byproducts of different biomaterials can be ascertained.

Chronic inflammation and fibrosis of the synovial membrane are often present in osteoarthritis and post-total joint arthroplasty. Our results suggest that the progression of inflammatory synovial diseases is influenced by macrophage phenotypes.