Intervertebral Disc Chondrocytes Research Articles

The intervertebral disc from embryonic development to disc degeneration: insights into spatial cellular organization

Background contextLow back pain is commonly attributed to intervertebral disc (IVD) degeneration. IVD resembles articular cartilage in its biochemical and cellular composition in many ways. For articular cartilage, degeneration stage-specific characteristic spatial chondrocyte patterns have recently been described. PurposeThis study addresses how spatial chondrocyte organization in the IVD changes from early embryonic development to end stage degeneration. Study designEx vivo immunohistochemical analysis. MethodsWe immunohistochemically investigated bovine IVD-tissue (n=72) from early embryonic development to early disc degeneration and human adult IVD-tissue (n=25) operated for trauma or degeneration for cellular density and chondrocyte spatial organization. IVD samples were sectioned along the main collagen fiber orientation. Nuclei were stained with DAPI and their number and spatial patterns were analyzed in an area of 250,000 µm² for each tissue category. ResultsThe initially very high cellular density in the early embryonic bovine disc (11,431 cells/mm²) steadily decreases during gestation, growth and maturation to about 71 cell/mm² in the fully grown cattle. Interestingly, in human degenerative discs, a new increase in this figure could be noted (184 cells/mm). The IVD chondrocytes appear to be predominantly present as single cells. Especially in the time after birth, string-formations represent up to 32% of all cells in the anulus fibrosus, although single cells are the predominant spatial pattern (>50%) over the entire time. With increasing degeneration, the relative proportion of single cells in human IVDs continuously decreases (12%). At the same time, the share of cells organized in clusters increases (70%). ConclusionSimilar to articular cartilage, spatial chondrocyte organization appears to be a strong indicator for local tissue degeneration in the IVD. Clinical SignificanceIn the future these findings may be important for the detection and therapy of IVD degeneration in early stages.

Ginsenoside Rd inhibits IL-1β-induced inflammation and degradation of intervertebral disc chondrocytes by increasing IL1RAP ubiquitination.

Many compounds of ginsenosides show anti-inflammatory properties. However, their anti-inflammatory effects in intervertebral chondrocytes in the presence of inflammatory factors have never been shown. Increased levels of pro-inflammatory cytokines are generally associated with the degradation and death of chondrocytes; therefore, finding an effective and nontoxic substance that attenuates the inflammation is worthwhile. In this study, chondrocytes were isolated from the nucleus pulposus tissues, and the cells were treated with ginsenoside compounds and IL-1β, alone and in combination. Cell viability and death rate were assessed by CCK-8 and flow cytometry methods, respectively. PCR, western blot, and immunoprecipitation assays were performed to determine the mRNA and protein expression, and the interactions between proteins, respectively. Monomeric component of ginsenoside Rd had no toxicity at the tested range of concentrations. Furthermore, Rd suppressed the inflammatory response of chondrocytes to interleukin (IL)-1β by suppressing the increase in IL-1β, tumor necrosis factor (TNF)-α, IL-6, COX-2, and inducible nitric oxide synthase (iNOS) expression, and retarding IL-1β-induced degradation of chondrocytes by improving cell proliferation characteristics and expression of aggrecan and COL2A1. These protective effects of Rd were associated with ubiquitination of IL-1 receptor accessory protein (IL1RAP), blocking the stimulation of IL-1β to NF-κB. Bioinformatics analysis showed that NEDD4, CBL, CBLB, CBLC, and ITCH most likely target IL1RAP. Rd increased intracellular ITCH level and the amount of ITCH attaching to IL1RAP. Thus, IL1RAP ubiquitination promoted by Rd is likely to occur by up-regulation of ITCH. In summary, Rd inhibited IL-1β-induced inflammation and degradation of intervertebral disc chondrocytes by increasing IL1RAP ubiquitination.

Retraction notice for: "Ginsenoside Rd inhibits IL-1β-induced inflammation and degradation of intervertebral disc chondrocytes by increasing IL1RAP ubiquitination" [Braz J Med Biol Res (2019) 52(9): e8525

[This retracts the article doi: 10.1590/1414-431x20198525].

Association between the Number of Chondrocytes of Lumbar Intervertebral Discs and Age, Abdominal Aorta Atherosclerosis and Lumbar Artery Arteriosclerosis Descriptive Cross Sectional Study

Background: The effect of age, atherosclerotic changes of abdominal aorta and arteriosclerotic changes of lumbar arteries on number of chondrocytes of lumbar intervertebral discs has not been studied. Methods: A descriptive cross sectional post mortem study was carried out in Faculty of Medicine, University of Kelaniya, Sri Lanka to determine the association between the mean number of chondrocytes in the fifth lumbar intervertebral disc and age, the level of atherosclerotic changes of the lumbar abdominal aorta and arteriosclerotic changes of right and left, fourth lumbar arteries. The presence or absence of atherosclerotic plaques in the abdominal aorta lumbar region was studied. To assess arteriosclerotic changes, the Intima Media thickness (IMT) and the total thickness (TT) of lumbar arteries were measured and the ratio IMT/TT was calculated. Bivariant analysis and a multi variant analysis were done. Results: There were 51 samples in total. Their ages ranged from 18 to 96 years. The mean age (SD) was 43 (± 17.1) years. The samples were obtained from 38 males and 13 females. There was a significant negative association (P<0.001; Beta Coefficient=- 0.95) between the age of the subject and the mean number of chondrocytes in the intervertebral disc. There was no significant association between atherosclerotic changes of abdominal aorta and arteriosclerotic changes of lumbar arteries and the mean number of chondrocytes. Conclusion: Only the age had a significant negative association with the mean number of chondrocytes of the intervertebral disc.

Cell-Based Therapies Used to Treat Lumbar Degenerative Disc Disease: A Systematic Review of Animal Studies and Human Clinical Trials.

Low back pain and degenerative disc disease are a significant cause of pain and disability worldwide. Advances in regenerative medicine and cell-based therapies, particularly the transplantation of mesenchymal stem cells and intervertebral disc chondrocytes, have led to the publication of numerous studies and clinical trials utilising these biological therapies to treat degenerative spinal conditions, often reporting favourable outcomes. Stem cell mediated disc regeneration may bridge the gap between the two current alternatives for patients with low back pain, often inadequate pain management at one end and invasive surgery at the other. Through cartilage formation and disc regeneration or via modification of pain pathways stem cells are well suited to enhance spinal surgery practice. This paper will systematically review the current status of basic science studies, preclinical and clinical trials utilising cell-based therapies to repair the degenerate intervertebral disc. The mechanism of action of transplanted cells, as well as the limitations of published studies, will be discussed.

Coculture of Notochordal Cells with Nucleus Pulposus and Annulus Fibrosus Cells under Normoxia and Hypoxia

Introduction Notochordal cells (NC) are shifted back into focus due to their apparent action of activating other disc cells via indirect release of yet unknown factors into the medium (conditioned medium = CM).1,2 Recent evidence confirms the results from the late 1990s.3,4 Here, we test porcine (p) NC cultured in 3D and the influence of adding serum or using serum-free medium onto the culture on NC cells and its stimulating effects for subsequent coculture with primary bovine (b) nucleus pulposus (bNPC) and annulus fibrous cells (bAFC). Materials and Methods Primary pNC, bNPC, and bAFC were isolated from porcine tails (< 6-12 months age) or bovine tails (∼1 year age), which were obtained from the food chain (N = 4 repeats) within 4 hours postmortem. All cells were seeded into 1.2% alginate, each with a density of 4 × 106/mL. NC were then either cultured for 7 days in serum free medium (SFM = Dulbecco modified eagle medium [DMEM] supplied with ITS+, 50 µg/mL vitamin C and nonessential amino acids) or DMEM + 10% fetal calf serum (FCS). CM was produced from NC collecting 4 mL SFM and keeping approximately 30 beads for 7 days. Then, a coculture was set up in SFM for 14 days using indirect cell-cell contact (culture insert, high density pore, 0.4 µm) using a 50:50% ratio5 of pNC:bNP or bAF, or by addition of CM, respectively. The cell activity, glycosaminoglycan per DNA (GAG/DNA) ratio, and real-time RT-PCR of IVD relevant genes were monitored. Mass spectrometry was performed on the SFM and the cocultured medium as well as the CM of the pNC to identify possible key cytokines to the stimulatory effects. Results The results for cell activity confirmed that pNC are highly responsive on the nutritional condition in the culture (K-W test, p = 0.048) after 7 days of coculture. bNPC and bAFC did not respond significantly different to coculture or addition of CM with respect to cell activity. However, GAG/DNA ratio of pNC was significantly upregulated if they were initially pre-exposed to FCS and in coculture with bNPC after 14 days, for both normoxia and hypoxia (K-W, p = 0.03). The bNPC were stimulated by both, 1:1 coculture with pNC but also by addition of CM only, which resulted in approximately 200% increased GAG/DNA values relative to the day 0 state. However, this doubling of the GAG/DNA ratio was nonsignificant after 14 days. The aggrecan/collagen type 2 ratio as quantified from real-time RT-PCR pointed to a beneficial state of the bNPC if cultured either in indirect coculture with pNC or by the addition of CM (Fig. 1). The mass spectrometric analysis of the CM revealed that there was connecting tissue growth factor present (CTGF) among the cytokine CLC11, a cytokine that has been found to be expressed in skeletal tissues including bone marrow and chondrocytes among other factors that might have immunoregulatory and cell proliferative functions.

Diversity of intervertebral disc cells: phenotype and function

The intervertebral disc (IVD) is a moderately moving joint that is located between the bony vertebrae and provides flexibility and load transmission throughout the spinal column. The disc is composed of different but interrelated tissues, including the central highly hydrated nucleus pulposus (NP), the surrounding elastic and fibrous annulus fibrosus (AF), and the cartilaginous endplate (CEP), which provides the connection to the vertebral bodies. Each of these tissues has a different function and consists of a specific matrix structure that is maintained by a cell population with distinct phenotype. Although the healthy IVD is able to balance the slow matrix turnover of synthesis and degradation, this balance is often disturbed, leading to degenerative disorders. Successful therapeutic management of IVD degeneration requires a profound understanding of the cellular and molecular characteristics of the functional IVD. Hence, the phenotype of IVD cells has been of significant interest from multiple perspectives, including development, growth, remodelling, degeneration and repair. One major challenge that complicates our understanding of the disc cells is that both the cellular phenotype and the extracellular matrix strongly depend on disc maturity and health and as a consequence are continuously evolving. This review delineates the diversity of the cell types found in the intervertebral disc, with emphasis on human, but with reference to other species. The cells of the NP appear rounded and express a proteoglycan-rich matrix, whereas the more elongated AF cells are embedded in a collagen fibre matrix and the CEPs represent a layer of cartilage. Even though all disc cells have often been referred to as 'intervertebral disc chondrocytes', distinct phenotypical differences in comparison with articular chondrocytes exist and have been reported recently. The availability of more specific markers has also improved our understanding of progenitor cell differentiation towards an IVD cell phenotype. Ultimately, new cell- and tissue-engineering approaches to regenerative therapies will only be successful if the specific characteristics of the individual tissues and their context in the function of the whole organ, are taken into consideration.

Optimizing nonviral-mediated transfection of human intervertebral disc chondrocytes

Background context The use of viral vectors for transfection of human disc chondrocytes has been well documented. However, because of immunological and cell toxicity concerns, nonviral reagents may provide gene delivery to intervertebral disc (IVD) chondrocytes without these associated obstacles. Several studies have been done using nonviral delivery systems with varying degrees of success. Purpose The purpose of the study was to determine the efficiency, toxicity, and optimal conditions for gene delivery into human degenerative IVD cells via nonviral reagents in vitro. Study design/setting In vitro viral and nonviral gene transfer. Patient sample Human disc chondrocytes from 21 patients undergoing discectomy for trauma, disc herniation, and fusion for scoliosis or degenerative low back pain. Outcome measures Cell cytotoxicity and transfection efficiency as determined by microscopy, luciferase assay, and flow cytometry. Methods Seventeen lipid-based nonviral reagents coupled to DNA plasmids coding for luciferase were transfected into cultured chondrocytes. Cells were transfected with varying ratios of DNA plasmid to reagent, harvested at 48 hours and analyzed for transfection rates and cell viability. Transfections with adenoviral constructs were comparisons. The three most efficient reagents were then coupled to green fluorescent protein and the experiments repeated. The most efficient reagent after these experiments (LT1) was tested in standard chondrocyte-maintenance medium and a minimal medium mixture devoid of antibiotics, buffers, and amino acids. Finally, LT1 in minimal medium with various hyaluronidase treatments was tested. The most effective reagents and relative toxicity as measured by flow cytometry were analyzed using repeated measures analysis of variance. Results LT1 was most efficient and least toxic of nonviral reagents tested. LT1 had a mean percent survival of 78.1% versus 26.6% for TKO, 15.8% for T-Jurkat, and 70.8% in controls. Transfection was 1.5%. LT1 in minimal medium was significantly better than other reagents for both cell viability and transfection percentages. Minimal medium increased transfection with other reagents, yet cell viability with TKO and T-Jurkat was poor. Hyaluronidase had no effect on the viability of controls and decreased viability from 74.9% to an overall mean of 62.6% for all treatments. Transfection percentages increased from 1.8% without treatment to 15.2% with 40 units and 10.4% with four units of hyaluronidase given 24 hours before transfection and left in throughout the experiment. When treated at the time of transfection, efficiency was not significantly different to samples without hyaluronidase added. Additionally, hyaluronidase added 24 hours before transfection and washed out at the time of transfection significantly increased transfection percentages. Conclusions LT1 was the most efficient reagent in terms of transfection ability and cell toxicity compared with other reagents. Treatments in minimal medium yielded significant increases in transfection and no significant difference in toxicity as compared with controls. Hyaluronidase treatments improve transfection significantly but also increase toxicity. These results suggest that the nonviral reagent LT1 can be used to transfect IVD chondrocytes in vitro and may help facilitate gene transfection of IVD chondrocytes in vivo.

Nucleus pulposus notochord cells secrete connective tissue growth factor and Up‐regulate proteoglycan expression by intervertebral disc chondrocytes

To identify the components of conditioned medium obtained from intervertebral disc nucleus pulposus-derived canine notochord cells, and to evaluate the capacity of such factors to affect disc-derived chondrocyte gene expression of aggrecan, versican, and hyaluronic acid synthase 2 (HAS-2) as a function of culture conditions. Canine notochord cells obtained from nonchondrodystrophic dogs were cultured within alginate beads under conditions of serum deficiency (Dulbecco's modified Eagle's medium [DMEM]) to produce notochord cell-conditioned medium (NCCM). NCCM was evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and liquid chromatography-tandem mass spectroscopy. Bovine disc-derived chondrocytes were cultured with serum-deficient medium (DMEM) and NCCM and assayed for the effect of tissue culture conditions on aggrecan, versican, and HAS-2 gene expression. Next, chondrocyte gene expression for aggrecan was evaluated using DMEM containing recombinant connective tissue growth factor (rCTGF), and the results compared with those obtained using NCCM and DMEM. NCCM contained aggrecan, Cu/Zn superoxide dismutase, fibronectin, and CTGF precursor. Culture with NCCM caused an up-regulation of aggrecan, versican, and HAS-2 gene expression. NCCM induced aggrecan gene expression in chondrocytes at a level similar to that induced by 100-200 ng/ml rCTGF. Nonchondrodystrophic and chondrodystrophic canine notochord cells exhibited similar levels of CTGF gene expression. Nucleus pulposus-derived notochord cells secrete CTGF (CCN2), a recently discovered multifunctional growth factor. There is no difference between CTGF gene expression in nonchondrodystrophic and chondrodystrophic canine notochord cells, suggesting a possible role of CTGF as an anabolic factor within the disc nucleus that is, to at least some degree, dependent on the population of notochord cells within the disc nucleus.

P93. Non-Viral Mediated Transfection of Human Intervertebral Disc Chondrocytes

BACKGROUND CONTEXT: The use of viral vectors for transfection of human disc chondrocytes has been well documented. However, due to immunological and cell toxicity concerns, nonviral vectors may provide gene delivery to intervertebral disc (IVD) chondrocytes without these associated obstacles. Several studies have been done utilizing nonviral vectors with varying degrees of success.

Expression pattern and functional characterization of connexin29 in transgenic mice

Using newly generated transgenic mice in which the coding region of the connexin29 (Cx29) gene was replaced by the lacZ reporter gene, we confirmed previous immunochemical results that Cx29 is expressed in Schwann cells, oligodendrocytes and Bergmann glia cells. In addition, we detected lacZ/Cx29 in Schwann cells of the sciatic nerve and in particular of the spiral ganglion in the inner ear, as well as at low abundance in the stria vascularis. Furthermore, we found lacZ/Cx29 expression in nonmyelinating Schwann cells of the adrenal gland, in chondrocytes of intervertebral discs and the epiphysis of developing bones. Electron microscopic analyses of myelin sheaths in the central and peripheral nervous system of Cx29-deficient mice detected no abnormalities. The nerve conduction in the sciatic nerve of adult Cx29-deficient mice and the auditory brain stem response as well as visually evoked potentials in 4- to 10-week-old Cx29-deficient mice were not different from wild-type littermate controls. Thus, in contrast to connexin32 and connexin47, which are also expressed in myelinating cells, Cx29 does not contribute to the function of myelin in adult mice.

Effects of Yiqi Huayu Recipe on gene expression pattern of normal and apoptotic chondrocytes in cervical intervertebral disc in rats

To study the effects of Yiqi Huayu Recipe on the gene expression pattern in normal and apoptotic chondrocytes in the cervical intervertebral disc of rats. The intervertebral disc endplates of rats were digested enzymatically. The apoptosis of the chondrocytes was induced by anti-Fas antibody. BiostarR-40s microarray chips were used to investigate the gene expression pattern in chondrocytes in the normal control, apoptosis and Yiqi Huayu Recipe groups. The results were scanned with Scan Array 4000 and analyzed with GenePix Pro 3.0, and then subjected to standardization and ratio analysis. In the apoptosis group, 30 kinds of genes expressed in cervical intervertebral disc chondrocytes were screened out, in which 10 were up-regulated (ratio>2) and 20 down-regulated (ratio<0.5) as compared with the normal control group. On the other hand, in the Yiqi Huayu Recipe group, 97 kinds of genes expressed in cervical intervertebral disc chondrocytes were screened out, in which 44 were up-regulated (ratio>2) and 53 down-regulated (ratio<0.5) as compared with the apoptosis group. There are some signal transduction pathways that control the apoptosis of the intervertebral disc chondrocytes. Yiqi Huayu Recipe regulates the gene express of the apoptotic chondrocytes in intervertebral disc. The study gives a further understanding to the mechanism of the cervical spondylosis and enriches the theories of qi and blood of traditional Chinese medicine.

Adenovirus mediated transfer of SOX-9 and bone morphogenetic protein–2 genes to human degenerative disc chondrocytes

Ronjon Paul, MD, T.C. He, MD, PhD, Frank M. Phillips, MD, Chicago, IL, USABackground: Human intervertebral disc degeneration is thought to be an important early event in the spinal “degenerative cascade” and is characterized by cell death with loss of water, proteoglycans and type 2 collagen. Transfer of genes encoding for growth factors that might inhibit or reverse these biologic processes may afford an opportunity to promote disc regeneration. The Sox-9 gene has been shown to be an essential transcription factor for type 2 collagen synthesis as well as for chondrogenesis. In humans, Sox-9 deficiency is associated with skeletal malformations. Bone morphogenetic protein (BMP)-2 has also been shown to stimulate type 2 collagen production as well as chondrogenesis. The goals of this study were to determine whether human degenerative intervertebral disc tissue and cells could be transduced with adenoviral vectors carrying Sox-9 or BMP-2 genes and as a result increase their synthesis of type 2 collagen.Materials and methods: Genes encoding for growth factors BMP-2 and Sox-9 were incorporated into defective recombinant adenovirus in tandem with a green fluorescent protein (GFP) marker. Intervertebral disc tissue was removed from six patients during surgery for a diagnosis of degenerative disc disease (institutional review board approval was obtained). In certain patients, nucleus pulposus tissue was cultured in DMEM medium for 48 hours. In other cases, disc cells were extracted from tissues using collagenase A (.1 μg/ml) dissolved in PBS for a period of 20 minutes. Cells were cultured at 37° C in standard DMEM complete medium for 14 to 25 days with media exchange every 3 to 4 days. Cell or tissue cultures were then transfected with adenovirus containing GFP marker, BMP-2 gene with GFP marker, or Sox-9 gene with GFP marker. Control cultures were treated with saline. Transfections were done at an MOI of 300. The medium of cell and tissue cultures was exchanged at 18 hours after exposure to the virus. Cell and tissue cultures were then washed in DMEM complete medium at 24 hours and then allowed to incubate. Samples were then evaluated at 36 hours and 1 week with fluorescent microscopy for signs of green fluorescent protein expression. At 1 week after viral exposure, tissue samples were sectioned and stained for type 2 collagen using an anti–type 2 collagen antibody. A secondary antibody and HRP indicator was used to complete the immunohistochemical staining process.Results: Viable chondrocytes were isolated and cultured from degenerative disc tissues. Cell viability remained high throughout the incubation and transfection periods (greater than 95%). In human degenerative disc cell cultures, fluorescent light microscopy documented 73% to 100% marker gene transfection. No cells were found to fluoresce in the uninfected control group. The tissue cultures transfected with virus showed evidence of sustained GFP expression as documented by fluorescence microscopy at 48 hours and 7 days. After transfection with the Sox-9 gene, disc tissue showed significantly increased levels of type 2 collagen using immunohistochemical staining up to 1 week after transfection (Table 1)Table 1Human degenerative disc transfection ratesGFP onlyBMP-2 + GFPSOX-9 + GFPControl48 hours93 + 12%91 + 15%93 + 12%0%7 days86 + 14%87 + 16%88 + 13%0%.Conclusion: This study confirms that degenerative human intervertebral disc chondrocytes can be transfected with potentially therapeutic genes. Previous studies of gene transfer in the intervertebral disc have used marker genes only or TGF-B1 for its wide range of potentially therapeutic effects. In this study, we used a gene encoding for Sox-9, a factor known to be critical for type 2 collagen synthesis and chondrogenesis. We were able to demonstrate Sox-9–mediated upregulation of type 2 collagen synthesis in degenerative human disc tissue. These observations suggest that this approach has potential applications for altering intervertebral disc degeneration.

Immunohistochemistry of chondromodulin-I in the human intervertebral discs with special reference to the degenerative changes.

The expression of the matrix protein chondromodulin-I has been studied in human intervertebral discs of 101 people using immunohistochemical analyses. The purpose of this report is to present data on the metabolic changes that were found to occur in the chondrocytes of intervertebral discs during development and aging. Chondromodulin-I was highly expressed during the gestational period and gradually decreased after maturation. It was detected in both the extracellular matrix and chondrocytes in the zone of hypertrophic cartilage, the zone of proliferative cartilage and the zone of resting cartilage in fetal discs. It was also present in the annulus fibrosus, nucleus pulposus and end-plate cartilage in mature discs. In degenerative discs, chondromodulin-1 immunoreactivity tended to be elevated in the remaining chondrocytes. Our findings suggest that the expression of the protein is developmentally regulated and upregulated through a defense mechanism against the degenerative processes of the aged intervertebral disc.

椎間板ヘルニアの自然吸収について 基礎研究の視点から

Many authors have reported that disc herniation can be resorbed by monocytic phagocytosis. However, how the recruitment of monocytes is triggered is still unknown.We investigated monocyte chemoattractant protein-1 (MCP-1) by using the experimental rat model in vivo and rabbit model in vitro to ascertain the precise mechanism of macrophage recruitment in the early phase of disc resorption.The autologous intervertebral discs from tails of Wister rat were subcutaneously implanted into the abdomen. These discs were used for immunohistochemical study. Additionally, we employed tissue culture models of rabbit's discs, and the quantification of MCP-1 in these media was performed.MCP-1 positive disc chondrocytes were observed in the nucleus pulposus and the inner annulus fibrosis on the third day. Monocyte derived macrophages were considerably observed around the intervertebral disc by the seventh day. The MCP-1 induced by rrlL-1β or rrTNFα indicated its peak volume at 12 hours and at 18 hours after incubation.Our study suggests that intervertebral disc chondrocytes have chemotactic properties and play an active role in the recruitment of monocytes involved in disc resorption. Moreover, inflammatory cytokines induce and regulate the production of MCP-1 in the intervertebral disc cells.

Monocyte chemoattractant protein-1 in the intervertebral disc. A histologic experimental model.

Monocyte chemoattractant protein-1 was investigated in an experimental rat model using immunohistochemistry. To ascertain the precise mechanism of macrophage recruitment in the early phase of disc resorption. In previous studies, many investigators reported that disc herniation was resorbed by monocytic phagocytosis. However, how the recruitment of monocytes was triggered is still unknown. The autologous intervertebral discs from tails of Wistar rats were subcutaneously implanted into the abdomen. These discs were obtained on days 2, 3, 7, and 14 after implantation and were used for immunohistochemical study and for quantitative analysis of monocyte chemoattractant protein-1 by sandwich enzyme-linked immunosorbent assay. Monocyte chemoattractant protein-1-positive granulocytes and macrophages were observed surrounding the intervertebral disc, and monocyte chemoattractant protein-1-positive disc chondrocytes were observed in the nucleus pulposus and the inner anulus fibrosus on day 3. By day 7, monocyte chemoattractant protein-1-positive and TRPM-3-positive macrophages appeared in the granulation tissue, and some of these cells invaded the nucleus pulposus and inner anulus fibrosus. The concentration of monocyte chemoattractant protein-1 was highest on day 3. Intervertebral disc chondrocytes have chemotactic properties and play an active role in the recruitment of monocytes involved in disc resorption.