Abstract
PurposeThe skeletal muscle develops various degrees of atrophy and metabolic dysfunction following nerve injury. Neurotrophic factors are essential for muscle regeneration. Human amniotic fluid derived stem cells (AFS) have the potential to secrete various neurotrophic factors necessary for nerve regeneration. In the present study, we assess the outcome of neurological function by intramuscular injection of AFS in a muscle denervation and nerve anastomosis model.Materials and MethodsSeventy two Sprague-Dawley rats weighing 200–250 gm were enrolled in this study. Muscle denervation model was conducted by transverse resection of a sciatic nerve with the proximal end sutured into the gluteal muscle. The nerve anastomosis model was performed by transverse resection of the sciatic nerve followed by four stitches reconnection. These animals were allocated to three groups: control, electrical muscle stimulation, and AFS groups.ResultsNT-3 (Neurotrophin 3), BDNF (Brain derived neurotrophic factor), CNTF (Ciliary neurotrophic factor), and GDNF (Glia cell line derived neurotrophic factor) were highly expressed in AFS cells and supernatant of culture medium. Intra-muscular injection of AFS exerted significant expression of several neurotrophic factors over the distal end of nerve and denervated muscle. AFS caused high expression of Bcl-2 in denervated muscle with a reciprocal decrease of Bad and Bax. AFS preserved the muscle morphology with high expression of desmin and acetylcholine receptors. Up to two months, AFS produced significant improvement in electrophysiological study and neurological functions such as SFI (sciatic nerve function index) and Catwalk gait analysis. There was also significant preservation of the number of anterior horn cells and increased nerve myelination as well as muscle morphology.ConclusionIntramuscular injection of AFS can protect muscle apoptosis and likely does so through the secretion of various neurotrophic factors. This protection furthermore improves the nerve regeneration in a long term nerve anastomosis model.
Highlights
Peripheral nerve injuries result in degeneration of nerve fibers and denervation of the innervated muscle
Given the inherent characteristics of neurotrophic factors secretion in human amniotic fluid derived stem cells (AFS) and the neurotrophic factors essential for muscle regeneration, we investigated the feasibility of AFS transplantations by injection into denervated muscle
AFS cells were cultured in 5 ml of β-minimum essential medium (β-MEM; Gibco-BRL) supplemented with 20% fetal bovine serum (FBS; Hyclone, Logan, UT, USA) and 4 ng/ml basic fibroblast growth factor in a 25 cm flask and incubated at 37°C with 5% humidified CO2
Summary
Peripheral nerve injuries result in degeneration of nerve fibers and denervation of the innervated muscle. Cell apoptosis plays a critical role in denervated muscle atrophy and degeneration [1,2]. Reducing or postponing cell apoptosis could provide treatment for skeletal muscle atrophy and degeneration [3,4]. Muscle denervation reduces mitochondrial contents and produces muscle atrophy [1]. Cytochrome c and apoptosisinducing factor are pro-apoptotic factors that can be released from these mitochondria through a specialized channel termed the mitochondrial permeability transition pore (mtPTP), leading to DNA fragments [5,6,7,8,9,10]. Denervated muscle has greater mitochondrial apoptotic susceptibility, which coincided with an increased ratio of Bax to Bcl-2 [6]. A reduction in apoptosis raises the possibility of lessening muscle atrophy and increasing muscle regeneration
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
