Objective To observe the morphologic changes of of vascular buds in vertebral cartilage endplate in age-specific rabbits and also to investigate the correlation between the changes of vascular buds and interverbral disc degeneration. Methods There were 15 New Zealand white rabbits in our study,which include three groups, 2-week-old rabbits, 1-year-old rabbits and 3-year-old rabbits, and each groups had five rabbits. The X-ray radiograph, histology and scanning electron microscope were used to observe the changes of vertebral cartilage endplate. According to Miyamoto standard, the interverbral disc was graded 1-5, and scored 1-5 respectively. Results The changes of micro-vascular structure of vertebral cartilage endplate were observed during aging. Under the scanning electron microscope, the vascular structure degenerated gradually, and disappeared in the end. The blood vessels in the central region of the vertebral cartilage endplate reduced more obviously than those in periphery region. The severe degeneration was found in vertebral endplate, compared with intervertebral disc. The changes of vascular buds in rabbits vertebral cartilage endplate had positive correlation with the vertebral endplate calcification and the interbertebral disc degeneration. Conclusion Changes of vascular buds in vertebral endplate may accelerate intervertebral disc degeneration.

BACKGROUND:To improve the mechanical properties and uncontrolability of degradation of decelularized matrix, wemanufactured genipin cross-linked decelularized annulus fibrosus matrix/chitosan hydrogels as annulus fibrosus tissue-engineereds caffold.
OBJECTIVE:To observe the biocompati bility of annulus fibrosus-derived stem cels with genipin cross-linked decelularized annulus fibrosus matrix/chitosan hydrogels, and the degradation of hydrogels in vivo.
METHODS:Genipin cross-linked decelularized annulus fibrosus matrix/chitosan hydrogels caffoldswere prepared, and the internal structure and hydrophilic property of hydrogels was detected by scanning electron microscopy and contact angle meter, respectively. Afterwards, passage 1 rabbit annulus fibrosus-derived stem cels were seeded on thescaffoldsfor 3 days, cel morphology was observed by inverted immun of luorescence microscopy and scanning electron microscopy after cytoskeleton staining, andadditionaly, curve of cel growth was obtained. In the meanwhile, thescafflodswere transplanted into theintermuscular space of New Zealand white rabbits, and the degradation and inflammatory reaction of the hydrogels were observedafter4 weeks.
RESULTS AND CONCLUSION:The prepared hydrogelsc affoldshowed porous and network structure and the contact angle was (39.94±1.61)°; annulus fibrosus-derived stem cels adhered wel on thescaffold surfacewithafaster growth rate. Furthermore, at 4 weeks after trans plantation, the hydrogelin vivowas degraded, and inflammatory cels appeared. These findings indicate that genipin cross-linked decelularized annulus fibrosus matrix/chitosan hydrogels have good biocompati bility.

BACKGROUND:Endplate cartilage degeneration initiates intervertebral disc degeneration. AMP-activated protein kinase (AMPK) regulates the formation and degradation of cartilage. OBJECTIVE:To explore the role of AMPK in an in vitro natural degeneration model of chondrocytes derived from endplate of rat intervertebral discs. METHODS:Morphology of in vitro subcultured endplate chondrocytes of rat intervertebral discs at passages 0, 2, and 5 were observed under an inverted microscope fol owing cytoskeleton staining. Chondrocyte phenotype, proliferation, and the cartilage marker genes (type II col agen, proteoglycan, SOX-9, matrix metal oproteinase-3 and-13), and AMPK phosphorylation were determined by toluidine blue staining, MTT assay, real-time PCR analysis, and western blot assay, respectively. RESULTS AND CONCLUSION:The altered morphology, decreased proliferation ability, and phenotype loss were observed in chondrocytes with increased passage number. Gene expression of type II col agen, proteoglycan, SOX-9 was significantly decreased;while gene expression of matrix metal oproteinase-3 and-13 was significantly increased in endplate chondrocytes at passage 5 compared with those at passages 0 and 2. AMPK phosphorylation in endplate chondrocytes at passage 5 was significantly decreased. These findings indicate that AMPK phosphorylation is involved in in vitro natural degeneration of chondrocytes derived from the endplate of rat intervertebral discs, and the degeneration of endplate chondrocytes and intervertebral discs can be inhibited through the regulation of AMPK activity.