An in vitro study of dynamic cyclic compressive stress on human inner annulus fibrosus and nucleus pulposus cells.
BACKGROUND
Intervertebral disc (IVD) cells exhibit diverse biologic responses to compressive stress depending on the compressive stress type, magnitude, duration, and anatomic zone of IVD cell origin. The previous studies mainly focused on the effects of compressive stress on animal IVD tissue. Few studies have investigated the response of human IVD tissue to compressive stress.


OBJECTIVE
To assess the effect of dynamic cyclic compressive stress on biosynthesis of collagen and glycosaminoglycan of human inner annulus fibrosus (AF) and nucleus pulposus (NP) cells.


METHODS
Observation of moderate and high magnitudes of compressive stress on human IVD cell biosynthesis.


METHODS
Human IVD of adolescent idiopathic scoliosis case undergoing thoracoscopic discectomy and fusion was collected.


METHODS
Cell morphology, cell proliferation assay, as well as collagen and glycosaminoglycan content were examined in vitro.


METHODS
Intervertebral discs were cultured under 0.2 or 0.4 MPa of compressive stress at 1 Hz for 2 hours twice a day up to 7 days. These were compared with samples unloaded. The analysis was done via electron microscopy examination, cell proliferation assay, as well as collagen and glycosaminoglycan content analysis.


RESULTS
Collagen and glycosaminoglycan content in the inner AF and NP cells cultured under 0.2 MPa of compressive stress was significantly higher than that in the control cells but was significantly lower than that in the control cells under 0.4 MPa of compressive stress. The number of endoplasmic reticulum in the inner AF and NP cells cultured under 0.2 MPa of compressive stress was significantly higher than that in the control cells but was significantly lower than that in the control cells under 0.4 MPa of compressive stress.


CONCLUSIONS
These findings imply that biosynthetic characteristics of human inner AF and NP cells may vary under varying degrees of compressive stresses, which may result in varying amounts of extracellular matrix being secreted.
Hee
Hwan Tak
HT
Department of Orthopedic Surgery, National University Hospital, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119074. doshht@nus.edu.sg
Zhang
Jituan
J
Wong
Hee Kit
HK
D000293:Adolescent; D049109:Cell Proliferation; D003094:Collagen / Q000096:biosynthesis; D019245:Compressive Strength / Q000502:physiology*; D005109:Extracellular Matrix / Q000502:physiology; D006025:Glycosaminoglycans / Q000096:biosynthesis; D006801:Humans; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000502:physiology* / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission
D006025:Glycosaminoglycans; D003094:Collagen