Retinal cell and stem cell fusion: the key to treating retinal damage?

The findings of a study were recently published in the journal eBioMedicine, which suggested that fusing human retinal cells with adult stem cells may be a therapeutic option to treat retinal damage and visual impairment. 

Cell fusion events, when two cells combine to create a single entity, are rare in humans, but have been consistently detected in the liver, brain and gastrointestinal tract. A research team – led by Pir Cosma at the Center for Genomic Regulation (Barcelona, Spain) – have discovered that cell fusion events also take place in the human retina.  

The team fused Müller glia, which are a type of cell involved in the maintenance of the structure and function of the retina. To do so, the researchers utilized adult stem cells derived from human adipose tissue or bone marrow.  

Sergi Bonilla – first author of the study and postdoctoral researcher – stated: “importantly, the process was more efficient in the presence of a chemical signal transmitted from the retina in response to damage, resulting in rates of hybridization increasing twofold. This gave us an important clue for the role of cell fusion in the retina.” 

The team then injected the hybrid cells into a developing retinal organoid. They discovered that the hybrid cells had successfully engrafted into the tissue, and differentiated into cells closely resembling ganglion cells, which are a type of neuron essential for vision.   

Pia Cosma, who led the research team, stated: “salamanders and fish can repair damage caused to the retina thanks to their Müller glia, which differentiate into neurons that rescue or replace damaged neurons. Mammalian Müller glia have lost this regenerative capacity, which means retinal damage or degradation can lead to visual impairment for life. Our findings bring us one step closer to recovering this ability.” 

The research team suggested that there is remaining work to be completed before any treatment options emerge. They proposed that the retina might have a mechanism to regulate chromosome segregation, which is why the hybrid cells do not result in chromosomal instability. With further research this may result in treatment options for visual impairment or retinal damage. 

Source: Bonilla-Pons S, Nakagawa S, Bahima E et al. Müller glia fused with adult stem cells undergo neural differentiation in human retinal models. eBioMedicine.  https://doi.org/10.1016/j.ebiom.2022.103914 (2022) (Epub ahead of print).