Mitochondrial Transplantation Moderately Ameliorates Retinal Degeneration in Royal College of Surgeons Rats

Investigating Müller glia reprogramming in mice: a retrospective of the last decade, and a look to the future

Müller glia, as prominent glial cells within the retina, plays a significant role in maintaining retinal homeostasis in both healthy and diseased states. In lower vertebrates like zebrafish, these cells assume responsibility for spontaneous retinal regeneration, wherein endogenous Müller glia undergo proliferation, transform into Müller glia-derived progenitor cells, and subsequently regenerate the entire retina with restored functionality. Conversely, Müller glia in the mouse and human retina exhibit limited neural reprogramming. Müller glia reprogramming is thus a promising strategy for treating neurodegenerative ocular disorders. Müller glia reprogramming in mice has been accomplished with remarkable success, through various technologies. Advancements in molecular, genetic, epigenetic, morphological, and physiological evaluations have made it easier to document and investigate the Müller glia programming process in mice. Nevertheless, there remain issues that hinder improving reprogramming efficiency and maturity. Thus, understanding the reprogramming mechanism is crucial toward exploring factors that will improve Müller glia reprogramming efficiency, and for developing novel Müller glia reprogramming strategies. This review describes recent progress in relatively successful Müller glia reprogramming strategies. It also provides a basis for developing new Müller glia reprogramming strategies in mice, including epigenetic remodeling, metabolic modulation, immune regulation, chemical small-molecules regulation, extracellular matrix remodeling, and cell-cell fusion, to achieve Müller glia reprogramming in mice.

Therapeutic potential of adult stem cells-derived mitochondria transfer combined with curcumin administration into ARPE-19 cells in age-related macular degeneration model

OBJECTIVE

Mitochondria transfer from human Wharton's Jelly-derived mesenchymal stem cells (hWJ-MSCs-mt) and human endometrium-derived mesenchymal stem cells (hE-MSCs-mt), along with curcumin, were explored as potential treatments for age-related macular degeneration (AMD) caused by mitochondrial inefficiency, using a retinal model to assess impacts of curcumin and hWJ-MSCs-mt or hE-MSCs-mt on AMD.

METHODS

ARPE-19 cells established an in vitro AMD model. Cells were exposed to 0-50 μM curcumin for 24 hours to determine optimal concentration by assessing their viability. Immunofluorescence examined SOD1, TNF-α, and TGF-β levels at optimal hydrogen peroxide (H2O2) concentration. β-galactosidase staining and DCFH analysis evaluated H2O2-induced cellular senescence. Immunofluorescence assessed REP65, CRALBP1 (RLBP1), Pink1, and Parkin expression, whereas qRT-PCR analyzed Nrf2, Ire1a, ARMS2, HTRA1, RPE65, RLBP1, NOX4, and TOMM20 expression following co-treatment with curcumin and hWJ-MSCs-mt or hE-MSCs-mt.

RESULTS

Curcumin improved ARPE-19 cell survival under H2O2-induced oxidative stress by regulating SOD1, TNF-α, TGF-β, DCFH, and MDA levels. hWJ-MSCs-mt transfer increased RLBP1 and Parkin expression, whereas curcumin reduced Parkin expression. hE-MSCs-mt transfer upregulated Parkin, RPE65, Pink1, and RLBP1 expressions, with curcumin enhancing RPE65 expression. hWJ-MSCs-mt and curcumin combined more effectively downregulated expressions of stress-related genes (Nrf2, Ire1α, NOX4) and improved expression of mitochondrial function gene (TOMM20). hE-MSCs-mt transfer with curcumin synergistically enhanced expression of retinal health markers (RPE65, RLBP1) and downregulated expression of damage-associated genes (HTRA1, ARMS2) in AMD models.

CONCLUSION

Curcumin combined with hWJ-MSCs-mt or hE-MSCs-mt is a potential AMD therapy owing to its anti-inflammatory properties; however, further in vivo and human studies are needed to confirm its efficacy and safety.

Recent progress of principal techniques used in the study of Müller glia reprogramming in mice

In zebrafish, Müller glia (MG) cells retain the ability to proliferate and de-differentiate into retinal progenitor-like cells, subsequently differentiating into retinal neurons that can replace those damaged or lost due to retinal injury. In contrast, the reprogramming potential of MG in mammals has been lost, with these cells typically responding to retinal damage through gliosis. Considerable efforts have been dedicated to achieving the reprogramming of MG cells in mammals. Notably, significant advancements have been achieved in reprogramming MG cells in mice employing various methodologies. At the same time, some inevitable challenges have hindered identifying accurate MG cell reprogramming rather than the illusion, let alone improving the reprogramming efficiency and maturity of daughter cells. Recently, several strategies, including lineage tracking, multi-omics techniques, and functional analysis, have been developed to investigate the MG reprogramming process in mice. This review summarizes both the advantages and limitations of these novel strategies for analyzing MG reprogramming in mice, offering insights into enhancing the reliability and efficiency of MG reprogramming.

Mitochondrial transfer between BMSCs and Müller promotes mitochondrial fusion and suppresses gliosis in degenerative retina

Mitochondrial dysfunction and Müller cells gliosis are significant pathological characteristics of retinal degeneration (RD) and causing blinding. Stem cell therapy is a promising treatment for RD, the recently accepted therapeutic mechanism is cell fusion induced materials transfer. However, whether materials including mitochondrial transfer between grafted stem cells and recipient's cells contribute to suppressing gliosis and mechanism are unclear. In present study, we demonstrated that bone marrow mesenchymal stem cells (BMSCs) transferred mitochondria to Müller cells by cell fusion and tunneling nanotubes. BMSCs-derived mitochondria (BMSCs-mito) were integrated into mitochondrial network of Müller cells, improving mitochondrial function, reducing oxidative stress and gliosis, which protected visual function partially in the degenerative rat retina. RNA sequencing analysis revealed that BMSCs-mito increased mitochondrial DNA (mtDNA) content and facilitated mitochondrial fusion in damaged Müller cells. It suggests that mitochondrial transfer from BMSCs remodels Müller cells metabolism and suppresses gliosis; thus, delaying the degenerative progression of RD.

Mitochondrial transplantation and transfer: The promising method for diseases

Mitochondria are organelles that serve as the powerhouses for cellular bioenergetics in eukaryotic cells. It is responsible for mitochondrial adenosine triphosphate (ATP) generation, cell signaling and activity, calcium balance, cell survival, proliferation, apoptosis, and autophagy. Mitochondrial transplantation is a promising disease therapy that involves the recovery of mitochondrial dysfunction using isolated functioning mitochondria. The objective of the present article is to provide current knowledge on natural mitochondrial transfer processes, in vitro and in vivo applications of mitochondrial transplantation, clinical trials, and challenges associated with mitochondrial transplantation.