|Budget Amount *help
¥2,400,000 (Direct Cost : ¥2,400,000)
Fiscal Year 1998 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1997 : ¥1,600,000 (Direct Cost : ¥1,600,000)
[Purpose] The purpose of these consecutive studies is to discuss whether an existence of the nucleus pulposus (NP) in degenerated discs plays an important role of decelerating further disc degeneration or not, using two animal models with the reinserted nucleus pulposus at the long term follow-up, and investigate biochemical influences between NP and the anulus fibrosus (AF) in vitro.
[Materials and Methods] The study was composed of 2 experiments. Experimental study -1 : An animal model of disc herniation was induced in 40 Wistar rats between 5th and 8th Coccyx and NP from Coccyx 5/6 and 6/7 was aspirated (PN). After PN, afresh NP was inserted into Coccyx 5/6. (Coccyx 6/7 served as asham control, 7/8 as a control, and 8/9 as a donor disc). Two, 4, 10 and 16 weeks after reinsertion, specimens from each disc were studied histopathologically regarding the structural integrity and an emergence of apoptosis cells. Experimental study-2 : An animal model of disc herniation was induced in 20 Japanese white rabbits. Two weeks alter PN, NP from L2/3 and L3/4 was reinserted into L415 and L5/6. In 2, 4, 8, and 16 weeks after reinsertion, specimens from each disc were studied histologically and type II collagen was tested utilizing aconfocal laser scanning microscopy (CLSM).
[Results] Degenerative changes of AF and an end plate gradually progressed with time after PN.Large round cells identified as notochord cells were decreased in number and replaced by small elongated fibroblast-like cells. Chondrocyte-like cells were also occasionally found in the reversed AF.These degenerative changes were less evident in reinserted discs of NP.Apoptosis cells around the inner layer of AF were noted in the discs with reinserted pulposus and very less observed in nonreinserted disc. A fluorescent intensity of Type II collagen in AF of a nonreinserted disc was high n the inner layer and low in the outer, compared with slight changes in a reinserted disc.