Abstract: P813

Type: Poster

Abstract Category: MS symptoms

Background: Multiple sclerosis (MS) is associated with loss of skeletal muscle mass and function. The myogenic stem cells (satellite cells - SCs) are instrumental for accretion of additional nuclei to the post-mitotic muscle cells, but remains to be investigated in MS.

Objectives: The present study compared the SC and myonuclei content between MS patients (n=23) and age matched healthy controls (HC, n=18). Furthermore, the effects of 12 weeks of high intensity training on SC and myonuclei content were explored in MS.

Methods: Muscle biopsies were obtained from m. Vastus Lateralis at baseline (MS+HC) and following 12 weeks of training (MS only). Frozen biopsies were sectioned followed by immunohistochemical analysis for fiber type specific SCs (Pax7⁺), myonuclei (MN) and central nuclei content and fiber cross-sectional area (fCSA) using ATPase histochemistry.

Results: At baseline the SCs/fiber was lower in type II compared to type I fiber in both MS (119%, p< 0.01) and HC (69%, p< 0.05), whereas the SCs/fCSA was lower in type II fibers compared to type I only in MS (72%, p< 0.05). No differences were observed in MN or central nuclei between MS and HC. Following training the type II fiber SCs per fiber and fCSA in MS patients increased by 165% (p< 0.05) and 135% (p< 0.05), respectively. Furthermore, the type II fiber MN content increased by 35% (p< 0.05) following training.

Conclusions: In conclusion, the SC content is lower in type II compared to type I fibers in both MS and HC. Furthermore, high intensity training was observed to selectively increase the SC and myonuclei content in type II fibers in MS patients.

Disclosure:

Inez Wens: nothing to disclose

Jean Farup: nothing to discclose

Charly Keytsman: nothing to disclose

Bert O. Eijnde: nothing to disclose

Ulrik Dalgas has received research support, travel grants and/or teaching honorary from Biogen Idec, Merck Serono and Sanofi Aventis.