Macrophage co-culture promotes cell reprogramming and prevents ferroptosis in aging fibroblasts for neurodegeneration therapy.

Ferroptosis, a form of programmed cell death associated with lipid peroxidation and iron dependency, plays a critical role in affecting neuronal function in the aging-related neurodegenerative diseases. Macrophages, influenced by these changes, contribute significantly to the progression of aging nerve diseases. Induced neuronal reprogramming is an advanced technology, which can direct convert somatic cells, such as fibroblasts, into neurons, and offers a promising approach for drug screening aimed at correcting ferroptosis and combating aging-related nerve diseases. However, the efficiency of this reprogramming process remains a significant challenge. In this study, we aimed to manipulate macrophage phenotypes to enhance the direct conversion of fibroblasts into neurons. Specifically, we sought to correct ferroptosis through screening natural compounds using aged fibroblasts and utilizing macrophages to promote induced neuronal (iN) reprogramming. Our findings demonstrate that M2 macrophages effectively promote the direct reprogramming of fibroblasts into iNs. In a novel macrophage-fibroblast co-culture system, M2 macrophages facilitate iN reprogramming by reducing fibroblast adhesion forces and promoting asymmetric cell division. Furthermore, we discovered that manipulating matrix stiffness can induce polarization of macrophages towards the M2 phenotype, thereby enhancing fibroblast reprogramming into iNs. To facilitate these findings, we developed a mechano-cue-based drug screening chip, where soft hydrogels induced and maintained the phenotype of M2 macrophages and effectively promoted cell reprogramming. Using a combinatorial approach with 36 such chips, we screened natural compounds for their anti-aging properties, focusing on reversing fibroblast aging and inducing their conversion into neuronal cells. Notably, Vitexin, an apigenin flavone glycoside with a role as a platelet aggregation inhibitor, emerged as a promising candidate to achieve our therapeutic goals. This study highlights the potential of macrophage-mediated modulation of fibroblast reprogramming as a strategy to address ferroptosis-induced neuronal dysfunction in aging-related nerve diseases. KEY MESSAGE: This study highlights the potential of macrophage-mediated modulation of fibroblast reprogramming as a strategy to address ferroptosis-induced neuronal dysfunction in aging-related nerve diseases.