Abstract
Purpose :
Microglia, the resident immune cells that reside within the retina are involved in the maintenance of retinal homeostasis via surveying their microenvironment and communicating with other neurons. Microglia get activated under stress and depending on their phenotype, exert either neurotoxic or neuroprotective effects to other cells by secreting several cytokines and signaling molecules. Polymeric scaffolds have the ability to regulate cellular responses through precisely designed cues. The purpose of present study is to assess the effect of polymeric nanofibers on microglial polarization and immunomodulatory responses under hypoxia, and their potential for the treatment of retinal inflammatory conditions.
Methods :
Human microglial CHME3 cells were grown on plain coverslips, as well as poly α-ester-based fibers possessing distinctly different topographies. Hypoxia was induced by the addition of CoCl2 for 24 h. Cell viability was measured using Alamar blue assay, cell shape using immunofluorescence, gene expression using qPCR and protein expression using western blotting. Statistical significance was calculated using ANOVA with a p value<0.05 considered significant.
Results :
Microglial cells proliferated well on polymeric scaffolds, and followed the topographical cues. Under normoxia, microglia cultured on fibers with specific topographies displayed a predominantly pro-inflammatory phenotype. Specifically, IL-6, GMCSF, TNF-α, and CXCL10 mRNA expression was significantly higher compared to the control group without nanofibers, and these trends largely reflected at the protein level too. Under hypoxia however, cells grown on fibers with different architectures showed a significantly higher viability, lower cell death and suppressed expression of the autophagy marker LC3 compared to the control group also cultured under hypoxia. Lysosomal proteins that protect the cells from apoptosis also showed higher expression when cultured on the scaffolds. Finally, expression of anti-inflammatory markers IL-4 and IL-10 was significantly higher on the scaffolds regardless of topography.
Conclusions :
The regulation of microglial phenotype by using engineered nanofibers with tightly controlled properties provides new insights and a potential therapeutic approach for the development of immunomodulatory therapy for retinal inflammatory diseases.
This is a 2021 ARVO Annual Meeting abstract.