Spinal Cord Injury (SCI) is one of medicine’s most formidable challenges, often leading to devastating and long-lasting motor, sensory, and bladder impairments. For decades, finding effective treatments for SCI has been a primary goal for researchers, and while progress has been made, true functional restoration has remained elusive.
However, a new and exciting player is emerging in the field of regenerative medicine: Human Multilineage-differentiating Stress-Enduring (Muse) cells. These unique stem cells, found naturally in our bodies, are showing groundbreaking potential, particularly for complex conditions like SCI. Recent studies, including a pivotal first-in-human clinical trial, are shedding light on how Muse cells could offer a new path to recovery.
What Makes Muse Cells the Body’s Natural Super-Healers?
Muse cells are not just any stem cells; they possess a remarkable “dual nature” that sets them apart from other somatic stem cells. As described by Mari Dezawa in Frontiers in Bioengineering and Biotechnology, Muse cells are both “pluripotent-like and macrophage-like” (Dezawa, 2025).
- Pluripotent-like: This means they have the ability to differentiate into a wide variety of cell types found in the body, such as nerve cells, muscle cells, or skin cells, enabling them to regenerate damaged tissues specifically.
- Macrophage-like: Like macrophages, the body’s immune clean-up crew, Muse cells can “phagocytose damaged/apoptotic cells” (Dezawa, 2025). This unique combination allows them to clear away unhealthy cells and then replace them with new, healthy, and functional ones, actively contributing to tissue repair and homeostasis.
Found in various tissues, including bone marrow, peripheral blood, and even the umbilical cord, Muse cells are truly “endogenous reparative stem cells” (Dezawa, 2025). Importantly, they are “non-tumorigenic,” addressing a major safety concern associated with some other pluripotent stem cells.
How Do Muse Cells Work Their Magic?
Muse cells’ therapeutic power comes from their sophisticated mechanisms:
- Smart Homing to Injury: Unlike many stem cells that struggle to reach injury sites, Muse cells act like intelligent navigators. They “selectively migrate to damaged sites by sensing one of the universal tissue damage signals, sphingosine-1-phosphate (S1P)” (Dezawa, 2025). This means they actively seek out and accumulate precisely where they are needed most.
- Clean-up and Direct Repair: Once at the site of damage, Muse cells efficiently engulf and remove damaged or dead cells. Following this “clean-up” phase, they rapidly differentiate into the specific cell types needed to replace the lost or injured cells, restoring function to the tissue.
- Immune Acceptance: A game-changer for cell therapy, Muse cells possess a unique “immune privilege.” This means they can be administered “without human leukocyte antigen (HLA) matching or immunosuppressant treatment” (Dezawa, 2025). This bypasses the need for donor matching and the potential side effects of immunosuppressive drugs, making the therapy much more accessible and safer for patients.
Why Muse Cells Stand Out from Other Stem Cells
While mesenchymal stem cells (MSCs) have been widely explored for regenerative medicine, Muse cells appear to overcome some of their key limitations. Studies have shown that MSCs often fail to yield significant efficacy because “only a few cells remain in the target organ and therefore remain in damaged tissues for short periods of time” (Yabuki et al., 2018). In contrast, Muse cells are remarkably good at homing to and surviving in injured tissues for extended periods. In a rat model of lung injury, Muse cells showed superior homing, remaining in the injured tissue in significantly higher numbers compared to MSCs (Yabuki et al., 2018).
A Breakthrough in Spinal Cord Injury: First Human Trial Shows Promise
The potential of Muse cells has now moved from preclinical studies to human trials. A recent clinical trial, published in Stem Cell Research & Therapy, investigated the “Safety and feasibility of intravenous administration of a single dose of allogenic-Muse cells to treat human cervical traumatic spinal cord injury” (Koda et al., 2024).
The study enrolled 10 participants with severe cervical SCI (affecting C4-C7), all of whom received a single intravenous dose of allogeneic Muse cells. Crucially, as with other Muse cell trials, no HLA matching or immunosuppressant treatment was required.
The findings were remarkably positive:
- Safety and Feasibility: The trial confirmed the “safety and feasibility” of administering Muse cells intravenously for SCI. Critically, the study reported “no causal relationship with severe adverse events” linked to the Muse cell treatment (Koda et al., 2024). This is a vital step in advancing any new therapy.
- Functional Improvements: Participants showed “statistically significant improvements” in key areas. This included the ISNCSCI motor score (a measure of motor function), as well as improved activity of daily living (ADL) and quality of life (QOL) scores (Koda et al., 2024). Specifically, motor scores showed continuous improvements up to 52 weeks post-administration compared to baseline, indicating a sustained positive effect.
The Road Ahead
These groundbreaking results are a significant step forward for the SCI community. The success in SCI mirrors promising outcomes in clinical trials for other challenging conditions such as stroke, ALS, and epidermolysis bullosa, further solidifying the broad therapeutic potential of Muse cells (Dezawa, 2025).
While future clinical trials with larger populations and control groups are needed to definitively confirm efficacy, the initial findings for SCI are a powerful testament to the unique reparative capabilities of Muse cells. They offer a tangible hope that, for conditions previously deemed untreatable, a new era of recovery through our body’s own natural healing mechanisms is on the horizon.
References:
- Dezawa, M. (2025). Macrophage- and pluripotent-like reparative Muse cells are unique endogenous stem cells distinct from other somatic stem cells. Frontiers in Bioengineering and Biotechnology, 13:1553382. DOI: 10.3389/fbioe.2025.1553382
- Koda, M., et al. (2024). Safety and feasibility of intravenous administration of a single dose of allogenic-Muse cells to treat human cervical traumatic spinal cord injury: a clinical trial. Stem Cell Research & Therapy, 15:259. https://doi.org/10.1186/s13287-024-03842-w
- Yabuki, H., Wakao, S., Kushida, Y., Dezawa, M., & Okada, Y. (2018). Human Multilineage-differentiating Stress-Enduring Cells Exert Pleiotropic Effects to Ameliorate Acute Lung Ischemia-Reperfusion Injury in a Rat Model. Cell Transplantation, 27(6), 979–993.