The evidence and the possible significance of autophagy in degeneration model of human cervical end-plate cartilage

Abstract

The aim of this study was to observe autophagy in chondrocytes from degenerative human cervical vertebral end-plates and to investigate the significance of variations in autophagy in the degeneration of cervical vertebral end-plate chondrocytes. Cartilage end-plates were obtained from 48 inpatients admitted to hospital between February 2011 and August 2012. The patients were divided into the control group (n=17) with cervical vertebral fracture or dislocation and the cervical spondylosis group (n=31) with cervical spondylotic myelopathy. End-plate chondrocytes were isolated via enzyme digestion and then cultured in vitro. The cells were stained with toluidine blue and hematoxylin-eosin (H&E). A laser scanning confocal microscope and monodansylcadaverine (MDC) were used to reveal autophagy in the end-plate chondrocytes. Reverse transcription polymerase chain reaction (RT-PCR) was used to detect mRNA expression of type II collagen and aggrecan. Western blotting was conducted to detect LC3 proteins. The chondrocytes isolated from the degenerative human cervical end-plates were cultured successfully in vitro. The morphology of the cells from the cervical spondylosis group tended to exhibit changes in spindle morphology compared with the control group. Autophagic bodies were stained with MDC. LC3 proteins were visible in the intracellular and perinuclear regions under the laser scanning confocal microscope. The mRNA expression levels (relative to those of β-actin) of aggrecan (0.715±0.194) and type II collagen (0.628±0.254) in the cervical spondylosis group were markedly decreased compared with those in the control group (0.913±0.254 and 0.845±0.186, respectively; both P<0.05). The LC3-II/LC3-I ratio was observed to be significantly reduced in the cervical spondylosis group by Western blot analysis. Autophagy has an important role in human cervical disc degeneration. The regulation of autophagy may prevent disc degeneration in cartilage end-plate cells.

Melatonin protects vertebral endplate chondrocytes against apoptosis and calcification via the Sirt1‐autophagy pathway

“…Autophagy has been proven by our group as well as other groups to postpone IDD processes in vitro and in vivo. Xu et al reported that rapamycin‐stimulated autophagy may inhibit intermittent mechanical stress‐induced calcification in cartilage EPCs . Chen et al demonstrated that oxidative stress induces autophagy in EPCs, while the inhibition of autophagy by bafilomycin A1 may increase apoptosis .…”

Autophagy: A double-edged sword in intervertebral disk degeneration

“…In chondrocytes isolated from the CEPs of patients with cervical spondylosis, the autophagosome number and ratio of LC3-II to LC3-I are significantly increased, with concomitant reductions in the aggrecan and Col II contents, implying that autophagy may have an important role in human cervical disc degeneration [80]. Regulation of autophagy in chondrocytes may provide a new direction for the treatment of degenerative disc disease.…”

Overexpression of BNIP3 in Rat Intervertebral Disc Cells Can Trigger Autophagy-Related Apoptosis

“…Ye et al (28) found that the number of autophagosomes and the ratio of autophagy-related proteins LC-3II/LC-3I in rat intervertebral disc nucleus pulposus cells increased with the age of rats. Xu et al (29) found that the autophagy level of endplate cells in IDD patients was lower than that in normal humans, while Gruber et al (30) showed that the autophagy level of the annulus brosus in patients with IDD was higher than that in normal humans. The above studies indicated it's discriminative on the exact roles of autophagy in IDD.…”