A Quantitative Assessment of the Changes in the Molecular Phenotype of the Rat Tail Intervertebral Disc Induced by Stereotactic, Image-Guided Needle Puncture
Bibliographic record
Abstract
Introduction A significant obstacle to the study of degenerative disc disease and therapeutic strategies to treat DDD has been the lack of a suitable animal model. Here, we detail a mechanistic investigation of the changes in the molecular phenotype of the cells within the intervertebral disc in a preclinical rodent model of IVD degeneration following needle puncture. Material and Methods Using a stereotactic device and fluoroscopic imaging control, we injured four IVDs/tail using 12-week-old female wistar rats and a 26-gauge needle. The needle was directed completely through the IVD annulus fibrosus (AD) to emerge through the contralateral annulus. The needle was then retracted back into the NP and after 1 minute, the needle was slowly removed over a further minute. The animals were allowed to recover for 10 weeks following which they were humanely euthanized and the discs recovered for biochemical, immunohistochemical, and protein analysis (Western blots). Results The healthy rat NP changes drastically 10-weeks following needle puncture injury such that the former notochordal cell-rich NP assumes a fibrocartilaginous phenotype by 10 weeks. Initially, there is an increase in the expression of the notochordal cell markers galectin-3 and brachyury beginning at 72 hours; however, these are undetectable by 10 weeks with only scant appearance of immunopositive cells. Before injury, there are barely detectable chondrocyte-like cell (CLC) markers such as carbonic anhydrase-12 and Sox9, however, following injury there is a steady increase in their expression maximizing by 4 to 8 weeks. The strong expression of the stemness marker Oct3/4 steadily increases its expression post injury that reaches a peak at 6 weeks; however, this stemness marker is undetectable at 10 weeks. A similar trend is seen with the cell signaling protein β-catenin that is barely detectable at baseline but is strongly expressed at 72 hours postinjury and steadily increases until 4 weeks and then decreases to lower level expression at 10 weeks. There is an increase in the expression of collagen types 1 and 2 beginning 72 hours postinjury with a continued increase through 10 weeks. Interestingly, there is a reciprocal relationship between the matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPS). MMP-3 and MMP-13 become detectable at 8 to 10 weeks precisely following the steady increase in expression of the natural inhibitor TIMP-1 which is completely undetectable when MMP-3 and MMP-13 increase their expression. ADAMTS-4 gradually increases its expression beginning at 72 hours through 8 weeks but is undetectable at 10 weeks. Conclusion Here, for the first time, we present a novel method of inducing degeneration in the rat tail IVD disc and have quantified the changes in the molecular phenotype of the IVD over 10 weeks. The injured rat tail IVD goes through a significant alteration in cellular and extracellular configuration that suggests a failed attempt on the part of notochordal and stem cells to induce repair resulting in the development of a fibrocartilaginous NP. This animal model and our characterization in the changes that causes postinjury can be used to quantify the effects of potential biological therapies in the treatment of DDD.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".