Severely atrophic human muscle fibers with nuclear misplacement survive many years of permanent denervation

Eur J Transl Myol, 2016 · DOI: · Published: April 1, 2016

Neurology Rehabilitation Musculoskeletal Medicine

Simple Explanation

Following spinal cord injury, human muscle fibers lose their myofibrillar apparatus, and the myonuclei relocate into clumps in the center of atrophic muscle fibers. These severely atrophic muscle fibers are more frequent in biopsies harvested three to six years after spinal cord injury. The study concludes that human muscle fibers can survive permanent denervation for a surprisingly long time, with nuclear relocation being a common characteristic.

Study Duration

1-10 years

Participants

24 patients with traumatic spinal cord injury

Evidence Level

Not specified

Key Findings

1
The percentage of muscle fibers with nuclear clumps increased significantly to 27 ± 9% between three to six years post-SCI.
2
This percentage decreased from the sixth year onward, coinciding with the onset of fibrosis in neurogenic muscle atrophy.
3
Immunohistochemical analyses revealed that nuclear misplacements occurred in both fast and slow muscle fibers.

Research Summary

The study investigates the survival of human muscle fibers after permanent denervation due to spinal cord injury (SCI) and the associated relocation of myonuclei. The findings indicate that severely atrophic muscle fibers with nuclear clumps are more prevalent in biopsies harvested three to six years after SCI but decrease as fibrosis progresses. The research suggests that human muscle fibers can survive denervation longer than previously thought, making nuclear clumps a notable feature of long-term denervated muscle.

Practical Implications

Targeted Research

The results offer a basis for research focused on recovering severely atrophic myofibers.

Combined Approaches

Combining molecular and cellular approaches with functional electrical stimulation may help restore muscle structure.

Clinical relevance

Nuclear clumps should be considered markers of the long-lasting ability of mammals muscle fibers to survive to the absence of the nerve.

Study Limitations

1
Small sample sizes in biopsy groups (n=6-11)
2
Demographic and clinical data was described in Kern H, et al. 2009, limiting specific information in this study.
3
Not specified

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