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Exp Neurol. 2017 Jan;287(Pt 2):216-224. doi: 10.1016/j.expneurol.2016.07.013. Epub 2016 Jul 21.

Inspiratory muscle conditioning exercise and diaphragm gene therapy in Pompe disease: Clinical evidence of respiratory plasticity.

Author information

1
Department of Physical Therapy, P.O. Box 100154, University of Florida, Gainesville, FL 32610, United States; Department of Pediatrics, P.O. Box 100144, University of Florida, Gainesville, FL 32610, United States. Electronic address: bksmith@phhp.ufl.edu.
2
Department of Physical Therapy, P.O. Box 100154, University of Florida, Gainesville, FL 32610, United States.
3
Department of Pediatrics, P.O. Box 100144, University of Florida, Gainesville, FL 32610, United States.
4
College of Liberal Arts and Sciences, P.O. Box 117300, University of Florida, Gainesville, FL 32611, United States.
5
College of Public Health and Health Professions, P.O. Box 100185, University of Florida, Gainesville, FL 21610, United States.
6
Department of Surgery, P.O. Box 100296, University of Florida, Gainesville, FL 32610, United States.
7
Department of Pediatrics Critical Care Division, University of Tennessee Health Science Center, 50 N. Dunlap, Memphis, TN 38103, United States.

Abstract

Pompe disease is an inherited disorder due to a mutation in the gene that encodes acid α-glucosidase (GAA). Children with infantile-onset Pompe disease develop progressive hypotonic weakness and cardiopulmonary insufficiency that may eventually require mechanical ventilation (MV). Our team conducted a first in human trial of diaphragmatic gene therapy (AAV1-CMV-GAA) to treat respiratory neural dysfunction in infantile-onset Pompe. Subjects (aged 2-15years, full-time MV: n=5, partial/no MV: n=4) underwent a period of preoperative inspiratory muscle conditioning exercise. The change in respiratory function after exercise alone was compared to the change in function after intramuscular delivery of AAV1-CMV-GAA to the diaphragm with continued exercise. Since AAV-mediated gene therapy can reach phrenic motoneurons via retrograde transduction, we hypothesized that AAV1-CMV-GAA would improve dynamic respiratory motor function to a greater degree than exercise alone. Dependent measures were maximal inspiratory pressure (MIP), respiratory responses to inspiratory threshold loads (load compensation: LC), and physical evidence of diaphragm activity (descent on MRI, EMG activity). Exercise alone did not change function. After AAV1-CMV-GAA, MIP was unchanged. Flow and volume LC responses increased after dosing (p<0.05 to p<0.005), but only in the subjects with partial/no MV use. Changes in LC tended to occur on or after 180days. At Day 180, the four subjects with MRI evidence of diaphragm descent had greater maximal voluntary ventilation (p<0.05) and tended to be younger, stronger, and use fewer hours of daily MV. In conclusion, combined AAV1-CMV-GAA and exercise training conferred benefits to dynamic motor function of the diaphragm. Children with a higher baseline neuromuscular function may have greater potential for functional gains.

KEYWORDS:

Diaphragm; Gene therapy; Pompe disease; Ventilatory insufficiency

PMID:
27453480
PMCID:
PMC5178134
DOI:
10.1016/j.expneurol.2016.07.013
[Indexed for MEDLINE]
Free PMC Article

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