Takuto Kurakawa1, Kenichiro Kakutani2, Yusuke Morita3, Yuki Kato3, Takashi Yurube1, Hiroaki Hirata1, Shingo Miyazaki1, Yoshiki Terashima1, Koichiro Maeno1, Toru Takada1, Minoru Doita1, Masahiro Kurosaka1, Nozomu Inoue4, Koichi Masuda5, Kotaro Nishida1. 1. Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyōgo Prefecture 657-8501, Japan. 2. Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyōgo Prefecture 657-8501, Japan. Electronic address: kenkakutani@gmail.com. 3. Department of Biomedical Engineering, Doshisha University, Karasuma-Higashi-iru, Kyoto, Kyoto Prefecture 602-8580, Japan. 4. Department of Biomedical Engineering, Doshisha University, Karasuma-Higashi-iru, Kyoto, Kyoto Prefecture 602-8580, Japan; Department of Orthopedic Surgery, Rush University Medical Center, 1653 W. Congress Parkway, Chicago, IL 60612, USA. 5. Department of Orthopaedic Surgery, University of California San Diego School of Medicine, 9500 Gilman Drive, La Jolla, San Diego, CA 92093, USA.
Abstract
BACKGROUND CONTEXT: Intervertebral disc (IVD) degeneration, a major cause of low back pain, is considered to be induced by daily mechanical loading. Mechanical stress is widely known to affect cell survival and extracellular matrix metabolism in many cell types. Although the involvement of integrin α5β1 transmembrane mechanoreceptor in IVD degeneration has been reported, the precise function of integrin α5β1 remains obscure. PURPOSE: To reflect IVD tissue response to mechanical stress using a dynamic loading organ culture system and elucidate the functional impact of integrin α5β1 on the pathomechanism of IVD degeneration. STUDY DESIGN: An ex vivo study using a dynamic loading organ culture system. METHODS: Ninety-six rat IVD explants were examined. Intervertebral discs were subjected to 1.3 MPa, 1.0 Hz dynamic compressive load in the presence or absence of an Arg-Gly-Asp (RGD) peptide with affinity to the fibronectin binding-site of integrin α5β1. Cell viability and histomorphology were assessed. The localization of integrin α5β1 in the IVD was assessed by immunohistochemistry. Gene expression levels of IVD cells were evaluated using real-time reverse transcription-polymerase chain reaction. RESULTS: In the nucleus pulposus (NP), cell density and viability were reduced by dynamic compressive load. Histologic degenerative alterations, mainly seen in the NP, were the morphologic changes of NP cells. In both NP and annulus fibrosus (AF), immunohistochemistry revealed localization of integrin α5β1 and that the messenger-RNA expression of integrin α5β1 was increased by dynamic load. Dynamic load induced a catabolic effect, the stimulation of matrix metalloproteinase-3 and -13 gene expressions by NP and AF cells. The RGD peptide partially blocked the histologic alterations and the catabolic effect. CONCLUSIONS: The dynamic loading organ culture system simulated cellular responses to mechanical loading of the IVD. Our results suggest that IVD cells recognize the mechanical stress through RGD integrins, particularly the α5β1 subtype that is highly expressed in NP and AF cells. Further experiments using this system will provide information about pathomechanisms of IVD degeneration through the mechanotransduction pathways.
BACKGROUND CONTEXT: Intervertebral disc (IVD) degeneration, a major cause of low back pain, is considered to be induced by daily mechanical loading. Mechanical stress is widely known to affect cell survival and extracellular matrix metabolism in many cell types. Although the involvement of integrin α5β1 transmembrane mechanoreceptor in IVD degeneration has been reported, the precise function of integrin α5β1 remains obscure. PURPOSE: To reflect IVD tissue response to mechanical stress using a dynamic loading organ culture system and elucidate the functional impact of integrin α5β1 on the pathomechanism of IVD degeneration. STUDY DESIGN: An ex vivo study using a dynamic loading organ culture system. METHODS: Ninety-six rat IVD explants were examined. Intervertebral discs were subjected to 1.3 MPa, 1.0 Hz dynamic compressive load in the presence or absence of an Arg-Gly-Asp (RGD) peptide with affinity to the fibronectin binding-site of integrin α5β1. Cell viability and histomorphology were assessed. The localization of integrin α5β1 in the IVD was assessed by immunohistochemistry. Gene expression levels of IVD cells were evaluated using real-time reverse transcription-polymerase chain reaction. RESULTS: In the nucleus pulposus (NP), cell density and viability were reduced by dynamic compressive load. Histologic degenerative alterations, mainly seen in the NP, were the morphologic changes of NP cells. In both NP and annulus fibrosus (AF), immunohistochemistry revealed localization of integrin α5β1 and that the messenger-RNA expression of integrin α5β1 was increased by dynamic load. Dynamic load induced a catabolic effect, the stimulation of matrix metalloproteinase-3 and -13 gene expressions by NP and AF cells. The RGD peptide partially blocked the histologic alterations and the catabolic effect. CONCLUSIONS: The dynamic loading organ culture system simulated cellular responses to mechanical loading of the IVD. Our results suggest that IVD cells recognize the mechanical stress through RGD integrins, particularly the α5β1 subtype that is highly expressed in NP and AF cells. Further experiments using this system will provide information about pathomechanisms of IVD degeneration through the mechanotransduction pathways.
Authors: K Luoma; H Riihimäki; R Luukkonen; R Raininko; E Viikari-Juntura; A Lamminen Journal: Spine (Phila Pa 1976) Date: 2000-02-15 Impact factor: 3.468
Authors: S Jane Millward-Sadler; Patrick W Costello; Anthony J Freemont; Judith A Hoyland Journal: Arthritis Res Ther Date: 2009-05-12 Impact factor: 5.156
Authors: Polly Lama; Harry Claireaux; Luke Flower; Ian J Harding; Trish Dolan; Christine L Le Maitre; Michael A Adams Journal: Cell Death Discov Date: 2019-12-17
Authors: Xiaohong Tan; Era Jain; Marcos N Barcellona; Evan Morris; Sydney Neal; Munish C Gupta; Jacob M Buchowski; Michael Kelly; Lori A Setton; Nathaniel Huebsch Journal: Biomaterials Date: 2021-09-01 Impact factor: 15.304