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

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. Introduction The aging population in China is becoming increasingly evident along with the acceleration in the pace of life. The number of individuals with neck pain has also increased, but the pathogenesis of this health problem remains unclear. The cartilage end-plate is an important part of the intervertebral disc. The degeneration of this end-plate is closely associated with intervertebral disc degeneration, which is a cell-mediated process. The chondrocytes are the major cell type in the cartilage end-plate. These cells have an important role in maintaining the physiological functions of the intervertebral disc and the integrity of the extracellular matrix (1). Apoptosis is considered an important factor in disc degeneration (2). Extensive clinical and animal model studies have shown that cell structure loss and cell death are associated with intervertebral disc degeneration (3). Therefore, studying the pathological physiology of chondrocytes is important. Autophagy is a form of apoptosis. In this process, cells engulf cytoplasmic proteins or organelles which are then packed into vesicles, and form an autophagolysosome with the lysosome. This process modulates metabolic materials and certain organelles. The autophagic process has four parts: substrate-induced porautophagosome, autophagy, fusion of the autophagosome with lysosomes and degradation of the contents of the autophagosome (4). Autophagy has a significant role in various degenerative pathological processes. For example, this mechanism is associated with cancer, microbial infections, heart diseases and even life extension (5,6). However, the association between autophagy and cartilage end-plate degeneration has rarely been studied. In this study, surgically removed cartilage end-plates from patients with cervical spondylosis were used to establish degenerative chondrocyte cultures through enzyme digestion. Cultured chondrocytes obtained from the cartilage end-plates of patients with cervical vertebral fracture or dislocation served as the control. In addition, autophagy in the cultured chondrocytes was observed and the significance of variations in autophagy in the degeneration of cervical vertebral endplate chondrocytes was investigated. Materials and methods Subjects. The subjects were cervical spine surgery patients admitted to Yijishan Hospital, Wannan Medical College The evidence and the possible significance of autophagy in degeneration model of human cervical end-plate cartilage HONGGUANG XU, SHOULIANG XIONG, HONG WANG, MIN ZHANG and YUNFEI YU Department of Orthopedic Surgery, Yijishan Hospital, Wannan Medical College, Wuhu, Anhui 241001, P.R. China Received July 25, 2013; Accepted December 2, 2013 DOI: 10.3892/etm.2013.1465 Correspondence to: Dr Hongguang Xu, Department of Orthopedic Surgery, Yijishan Hospital, Wannan Medical College, No. 2 of Zhe Shan Xi Lu Road, Wuhu, Anhui 241001, P.R. China E-mail: xuhg@medmail.com.cn