Genetically modified macrophages accelerate myelin repair

Area of Science:

• Neuroscience
• Regenerative Medicine
• Immunology

Background:

• Multiple sclerosis (MS) is characterized by neurodegeneration and disability progression, with remyelination offering a key neuroprotective strategy.
• Current therapeutic approaches face challenges in effectively targeting demyelinating lesions for molecular delivery.
• Semaphorin 3F (Sema3F) has shown potential in promoting remyelination by attracting oligodendrocyte progenitor cells (OPCs).

Purpose of the Study:

• To investigate the potential of using blood-derived cells, specifically monocytes/macrophages, as vehicles for delivering Sema3F to demyelinating lesions in MS.
• To establish a preclinical model using genetically modified hematopoietic stem cells (HSCs) for sustained Sema3F expression in circulating blood cells.

Main Methods:

• Hematopoietic stem cells (HSCs) were genetically modified to overexpress semaphorin 3F (Sema3F).
• Chimeric mice with circulating Sema3F-overexpressing monocytes were generated through HSC transplantation.
• Demyelinating lesions were induced, and OPC migration, inflammation, OPC survival, and remyelination onset were assessed.

Main Results:

• Sema3F-transduced HSCs led to enhanced OPC migration in a neuropilin 2 (Nrp2)-dependent manner.
• Sema3F-expressing blood cells accelerated the onset of remyelination in demyelinating lesions.
• No significant changes were observed in inflammation or OPC survival, indicating a specific pro-remyelinating effect.

Conclusions:

• Blood cells, particularly monocytes/macrophages, can serve as effective delivery vehicles for pro-remyelinating agents to MS lesions.
• This strategy offers a novel, targeted approach to promote remyelination and potentially halt neurodegeneration in multiple sclerosis.
• The findings support the development of cell-based therapies for enhancing myelin repair in MS.