From: david gobel (davegobel@erols.com)
Date: Wed Jan 27 1999 - 14:59:21 MST
Seen this?
Viral mediated expression of insulin-like growth factor I blocks the
aging-related loss of skeletal muscle function.
Barton-Davis ER, Shoturma DI, Musaro A, Rosenthal N, Sweeney HL
Department of Physiology, A700 Richards Building, University of Pennsylvania
School of Medicine, Philadelphia, PA 19104-6085, USA.
During the aging process, mammals lose up to a third of their skeletal
muscle mass and strength. Although the mechanisms underlying this loss are
not entirely understood, we attempted to moderate the loss by increasing the
regenerative capacity of muscle. This involved the injection of a
recombinant adeno-associated virus directing overexpression of insulin-like
growth factor I (IGF-I) in differentiated muscle fibers. We demonstrate that
the IGF-I expression promotes an average increase of 15% in muscle mass and
a 14% increase in strength in young adult mice, and remarkably, prevents
aging-related muscle changes in old adult mice, resulting in a 27% increase
in strength as compared with uninjected old muscles. Muscle mass and fiber
type distributions were maintained at levels similar to those in young
adults. We propose that these effects are primarily due to stimulation of
muscle regeneration via the activation of satellite cells by IGF-I. This
supports the hypothesis that the primary cause of aging-related impairment
of muscle function is a cumulative failure to repair damage sustained during
muscle utilization. Our results suggest that gene transfer of IGF-I into
muscle could form the basis of a human gene therapy for preventing the loss
of muscle function associated with aging and may be of benefit in diseases
where the rate of damage to skeletal muscle is accelerated.
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