Search

Recent studies have reported that low-intensity pulsed ultrasound (LIPUS) stimulates cell proliferation and proteoglycan production in rabbit intervertebral disc cells, and moreover promotes the secretion of MCP-1 (monocyte chemotaxis protein-1) from macrophages in a disc organ culture model. These findings suggest the possible application of LIPUS for biological repair of disc degeneration and herniation. Although the mechanisms involved are not well understood, several cytokine pathways may play a role. Therefore, in order to evaluate the effect of LIPUS stimulation on cytokine production by nucleus pulposus cells and macrophages, in vitro culture studies were designed. Nucleus pulposus cells and macrophages were collected from Sprague-Dawley rats, cultured separately in a monolayer, and stimulated with LIPUS for 7 days. After culture, the culture medium and the cells were analyzed by cytokine array, RT-PCR, and ELISA. Cytokine array showed that LIPUS stimulation significantly upregulated TIMP-1 (tissue inhibitor of metalloproteinase-1) in the nucleus pulposus and MCP-1 in macrophages in comparison with the control. This was confirmed at the gene level by RT-PCR in nucleus pulposus cells and macrophages after stimulation with LIPUS. Quantitative evaluation of these proteins by ELISA showed higher levels in nucleus pulposus cells and macrophages stimulated by LIPUS than in controls. These results showed that LIPUS stimulation significantly activated TIMP-1 and MCP-1 in nucleus pulposus cells and macrophages at both the protein and gene levels, suggesting that LIPUS may be a promising supplemental treatment for intervertebral disc herniation., ((c) 2008 Orthopaedic Research Society.)

The transforming growth factor-beta (TGF-beta) and the tumor necrosis factor-alpha (TNF-alpha) families are known to play important roles in intervertebral disc degeneration (IVD). However, molecular interactions between the TGF-beta and TNF-alpha signaling pathways have yet to be elucidated. The purpose of this study was to analyze the expression patterns of Smad transcription factor signaling associated with IVDs with aging and to examine the modulation of Smad signaling by TNF-alpha in IVD cells using SD rats. According to these experimental results, BMP signals in the TGF-beta family were more likely to be a key factor in IVD degeneration by aging, and it was predicted that besides the involvement of catabolic factors like MMPs and ADAMS-TS, there may be a decrease in expression of anabolic factors through cross talk of signaling between TNF-alpha and TGF-beta pathway in pathogenesis of disc degeneration.

Transplantation of mesenchymal stem cells (MSCs) is effective in decelerating disc degeneration in small animals; much remains unknown about this new therapy in larger animals or humans. Fas-ligand (FasL), which is only found in tissues with isolated immune privilege, is expressed in IVDs, particularly in the nucleus pulposus (NP). Maintaining the FasL level is important for IVD function. This study evaluated whether MSC transplantation has an effect on the suppression of disc degeneration and preservation of immune privilege in a canine model of disc degeneration. Mature beagles were separated into a normal control group (NC), a MSC group, and the disc degeneration (nucleotomy-only) group. In the MSC group, 4 weeks after nucleotomy, MSCs were transplanted into the degeneration-induced discs. The animals were followed for 12 weeks after the initial operation. Subsequently, radiological, histological, biochemical, immunohistochemical, and RT-PCR analyses were performed. MSC transplantation effectively led to the regeneration of degenerated discs. FACS and RT-PCR analyses of MSCs before transplantation demonstrated that the MSCs expressed FasL at the genetic level, not at the protein level. GFP-positive MSCs detected in the NP region 8 weeks after transplantation expressed FasL protein. The results of this study suggest that MSC transplantation may contribute to the maintenance of IVD immune privilege by the differentiation of transplanted MSCs into cells expressing FasL., ((c) 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Low-intensity pulsed ultrasound (LIPUS) has been reported to stimulate the activity of various cells. We have reported that the capacity of human intervertebral nucleus pulposus cell line to synthesize proteoglycan (PG) was increased by exposure to LIPUS, and postulated that one of the mechanisms underlying this response was an increase in expression of the transforming growth factor-beta type I receptor gene (TGFbetaR1). Therefore, the present study was conducted to assess the synergistic effect of LIPUS and TGF-beta on nucleus pulposus cells harvested from canines. The cells were cultured under four different sets of conditions: control group (Group A), LIPUS group (Group B), TGF-beta1 group (Group C), and LIPUS + TGF-beta1 group (Group D). They were evaluated by measuring cell proliferation, PG synthesis, PG content, gene expression of TGFbetaR1, and TGF-beta1 concentration. There were no significant differences in proliferation during culture. However, PG synthesis and endogenous TGF-beta1 production increased and demonstrated a synergistic effect between LIPUS and TGF-beta. Because LIPUS is safe and noninvasive, the results of the present study suggest that it would be a promising new therapy for prevention of intervertebral disc degeneration, which is said to be one of the primary causes of low back pain., (Copyright 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Intervertebral disc (IVD) degeneration, a common cause of low back pain in humans, is a relentlessly progressive phenomenon with no currently available effective treatment. In an attempt to solve this dilemma, we transplanted autologous mesenchymal stem cells (MSCs) from bone marrow into a rabbit model of disc degeneration to determine if stem cells could repair degenerated IVDs. LacZ expressing MSCs were transplanted to rabbit L2-L3, L3-L4 and L4-L5 IVDs 2 weeks after induction of degeneration. Changes in disc height by plain radiograph, T2-weighted signal intensity in magnetic resonance imaging (MRI), histology, immunohistochemistry and matrix associated gene expressions were evaluated between normal controls (NC) without operations, sham operated with only disc degeneration being induced, and MSC-transplanted animals for a 24-week period. Results showed that after 24 weeks post-MSC transplantation, degenerated discs of MSC-transplanted group animals regained a disc height value of about 91%, MRI signal intensity of about 81%, compared to NC group discs. On the other hand, sham-operated group discs demonstrated the disc height value of about 67% and MRI signal intensity of about 60%. Macroscopic and histological evaluations confirmed relatively preserved nucleus with circular annulus structure in MSC-transplanted discs compared to indistinct structure seen in sham. Restoration of proteoglycan accumulation in MSC-transplanted discs was suggested from immunohistochemistry and gene expression analysis. These data indicate that transplantation of MSCs effectively led to regeneration of IVDs in a rabbit model of disc degeneration as suggested in our previous pilot study. MSCs may serve as a valuable resource in cell transplantation therapy for degenerative disc disease.