Methods and compositions for rejuvenating skeletal muscle stem cells

1. A method of rejuvenating skeletal muscle stem cells in a subject in need thereof, comprising administering to the subject a composition which increases the level or activity of GDF11 polypeptide in the subject, wherein the composition comprises a GDF11 polypeptide or a functional fragment or functional variant thereof, wherein the functional fragment comprises at least the 12.5 kDa C-terminus of GDF11, and wherein the functional variant has at least 90% sequence identity to full length human mature GDF11, and wherein the composition causes the subject's skeletal muscle stem cells to increase in frequency or number, increase the sizes of regenerating myofibers, increase the efficiency of myogenic colony formation, increase the percentage of intact nuclei, and decrease the percentage of severely damaged deoxyribonucleic acid (DNA), thereby rejuvenating the skeletal muscle stem cells in the subject.

2. The method of claim 1 , wherein the level or activity of GDF11 polypeptide is increased in the skeletal muscle tissue of the subject.

3. The method of claim 1 , wherein the composition comprises a GDF11 polypeptide comprising the amino acid sequence of human mature GDF11.

4. The method of claim 1 , wherein the composition comprises a GDF11 polypeptide comprising the amino acid sequence of human GDF11 pro-peptide.

5. The method of claim 1 , wherein the composition comprises a GDF11 polypeptide comprising the amino acid sequence of human GDF11 precursor polypeptide.

6. The method of claim 1 , wherein the subject has been diagnosed with a skeletal muscle condition due to aging.

7. A method of increasing strength or exercise endurance capacity in a subject in need thereof, comprising administering to the subject a composition which increases the level or activity of GDF11 polypeptide in the subject, thereby increasing the strength or exercise endurance capacity, wherein the composition comprises a GDF11 polypeptide or a functional fragment or functional variant thereof, wherein the functional fragment comprises at least the 12.5 kDa C-terminus of GDF11, wherein the functional variant has at least 90% sequence identity to full length human mature GDF11, and wherein the composition causes the subject's skeletal muscle stem cells to increase in frequency or number, increase the sizes of regenerating myofibers, increase the efficiency of myogenic colony formation, increase the percentage of intact nuclei, and decrease the percentage of severely damaged deoxyribonucleic acid (DNA), thereby rejuvenating the skeletal muscle stem cells in the subject.

8. The method of claim 7 , wherein the composition comprises a GDF11 polypeptide comprising the amino acid sequence of human mature GDF11.

9. The method of claim 7 , wherein the composition comprises a GDF11 polypeptide comprising the amino acid sequence of human GDF11 pro-peptide.

10. The method of claim 7 , wherein the composition comprises a GDF11 polypeptide comprising the amino acid sequence of human GDF11 precursor polypeptide.

11. A method of treating or preventing a skeletal muscle condition in a subject in need thereof, comprising administering to the subject an effective amount of a composition which increases the level or activity of GDF11 polypeptide in the subject, wherein the composition causes the subject's skeletal muscle stem cells to increase in frequency or number, increase the sizes of regenerating myofibers, increase the efficiency of myogenic colony formation, increase the percentage of intact nuclei, and decrease the percentage of severely damaged DNA, thereby treating or preventing the skeletal muscle condition in the subject, wherein the composition comprises a GDF11 polypeptide or a functional fragment or functional variant thereof, wherein the functional fragment comprises at least the 12.5 kDa C-terminus of GDF11, and wherein the functional variant has at least 90% sequence identity to full length human mature GDF11.

12. The method of claim 11 , wherein the skeletal muscle condition is selected from the group consisting of atrophy, bony fractures associated with muscle wasting or weakness, cachexia, denervation, diabetes, dystrophy, exercise-induced skeletal muscle fatigue, fatigue, frailty, inflammatory myositis, metabolic syndrome, neuromuscular disease, obesity, post-surgical muscle weakness, post-traumatic muscle weakness, sarcopenia, toxin exposure, wasting, and weakness.

13. The method of claim 11 , wherein the compositions comprises a GDF11 polypeptide selected from the group consisting of a human GDF11 precursor polypeptide, a human GDF11 pro-peptide, and a human mature GDF11 and a human GDF11 N-terminal polypeptide.

14. The method of claim 11 , wherein the composition comprises homodimers of GDF11 polypeptides, and wherein the GDF11 polypeptides are selected from the group consisting of a human GDF11 precursor polypeptide, a human GDF11 pro-peptide, and a human mature GDF11 and a human GDF11 N-terminal polypeptide.