Original animal model of lumbar disc degeneration

Abstract

Purpose: Disc degeneration (DD) is a common cause of low back pain, which represents one of the most widespread public health problems in the world. Therefore, the establishment of a reproducible animal model is indispensable to understand the pathogenic mechanisms of DD and to test new therapeutic strategies. From this perspective, the fundamental objective of this study was to elucidate the effect of ovariectomy in establishing a new animal model of DD in rats. Methods: 36 female Sprague-Dawley rats were divided into four groups of 9 rats: Group 1: Negative control (Sham): Only an abdominal skin incision and sutures were performed. Group 2: Ovariectomy (OVX): Removal of two ovaries through a transverse incision in the middle of the abdomen. Group 3: Puncture (Punct): Puncture of lumbar intervertebral discs (L3/4, L4/5, and L5/6) by a 21 G needle. Group 4: Puncture+ovariectomy (Punct+OVX): Removal of two ovaries and puncture of L3/4, L4/5, and L5/6 discs. The rats were euthanized 1, 3, and 6 weeks post-surgery, and the discs were harvested. Validity was assessed by radiography, histology, and biochemistry (water content). Results: Disc height, water content, and histologic score decreased significantly in the last 3 groups and at all three-time points ( P < 0.05). DD progressed over time in the Punct and Punct+OVX groups ( P < 0.05). The changes were more severe in the Punct+OVX group compared to the Punct group and the OVX group. Conclusion: The combination of puncture and ovariectomy induced rapid and progressive DD in the lumbar discs of rats without spontaneous recovery.

Repetitive strikes loading organ culture model to investigate the biological and biomechanical responses of the intervertebral disc

“…The one strike group underwent MS on Day 2 and received daily loading at (0.02-0.2 MPa, 1 Hz, 1 h/day) from Day 1 to Day 32, with the remainder of the time spent in free swelling in the culture medium. In the repetitive one strike group, loading was conducted daily, excluding Days 2,5,8,11,14,17,20,23,26, and 29, with the remaining time allocated for free swelling in the culture medium. The chamber was filled with culture medium to prevent dehydration of IVDs.…”

“…For repetitive one strike group, MS was applied on following days: Days 2,5,8,11,14,17,20,23,26,29, and physiological loading was performed for the rest of the day up to Day 32 (long term).…”

“…Dynamic compression stiffness was evaluated at specific time points using a custom-designed bioreactor following overnight free swelling on Days 1,2,5,8,11,14,17,20,23,26,29, and 32. 19 The IVD underwent a 3-min preload, applying a 10% strain determined by the disc height measured before stiffness evaluation, followed by 10 rounds of sinusoidal compression ranging from 5% to 15% strain (10% strain/s).…”

“…9,10 Animal models resemble humans but face challenges with reproducibility and biological variations. 11,12 Depends on which model. Small animal does not resemble humans at all.…”

“…In vitro cell culture models simplify conditions but lack the in vivo mechanical cues 9,10 . Animal models resemble humans but face challenges with reproducibility and biological variations 11,12 . Depends on which model.…”