How the science and engineering of spaceflight contribute to understanding the plasticity of spinal cord injury

Abstract

Space programs support experimental investigations related to the unique environment of space and to the technological developments from many disciplines of both science and engineering that contribute to space studies. Furthermore, interactions between scientists, engineers and administrators, that are necessary for the success of any science mission in space, promote interdiscipline communication, understanding and interests which extend well beyond a specific mission. NASA-catalyzed collaborations have benefited the spinal cord rehabilitation program at UCLA in fundamental science and in the application of expertise and technologies originally developed for the space program. Examples of these benefits include: (1) better understanding of the role of load in maintaining healthy muscle and motor function, resulting in a spinal cord injury (SCI) rehabilitation program based on muscle/limb loading; (2) investigation of a potentially novel growth factor affected by spaceflight which may help regulate muscle mass; (3) development of implantable sensors, electronics and software to monitor and analyze long-term muscle activity in unrestrained subjects; (4) development of hardware to assist therapies applied to SCI patients; and (5) development of computer models to simulate stepping which will be used to investigate the effects of neurological deficits (muscle weakness or inappropriate activation) and to evaluate therapies to correct these deficiencies.

Introduction

Our laboratories study how the nervous system, particularly the spinal cord, controls movement. We also study how the neuromuscular system adapts to changes in the levels and patterns of use as well as to varying gravitational stimuli. More recently, the interaction of the neuronal and endocrine systems in the regulation of neuromuscular plasticity also has become a topic of acute interest. Each of these areas represent important topics for the study of both spinal cord injury (SCI) and gravitational biology. There are also many common benefits of gravitational biology which can be projected to problems associated with aging and with neural disorders such as SCI, stroke and cerebral palsy. The present paper, however, will focus principally on the interactions of SCI and gravitational biology. The impact of gravitational biology to medicine is of a significant magnitude. For example, each year there are over 10,000 SCI and 500,000 stroke patients that are admitted to hospitals, 75% of whom might benefit from being retrained to walk using some of the physiological principles that have evolved from studies of gravitational loading and locomotion in rats, cats, monkeys and humans [1]. In addition, the recent discovery that prolonged bedrest and spaceflight depress the release of some growth factors has enormous clinical implications to the problems of skeletal muscle atrophy and weakness in any condition when the patient is bedridden.