Immunomodulatory effectiveness of tacrolimus in preventing epidural scar adhesion after laminectomy in rat model

The Preventive Effect of Decorin on Epidural Fibrosis and Epidural Adhesions After Laminectomy

Laminectomy is commonly performed to treat degenerative spinal diseases by reducing compression on the spinal cord and nerve roots. The postoperative epidural fibrosis and epidural adhesions may result in failed back surgery syndrome, which is characterized by the symptoms of lower back pain or leg pain. There is currently no satisfactory treatment for this complication. The pathological processes of epidural fibrosis and epidural adhesions are relevant to the proliferation of fibroblasts, transdifferentiation of fibroblasts into myofibroblasts, and the excessive deposition of extracellular matrix (ECM) protein. According to reports, transforming growth factor-β1 (TGF-β1) played a vital role in the development of fibrosis by promoting aforementioned processes. Decorin, an endogenous proteoglycan and natural inhibitor of TGF-β1, has exhibited prominent anti-fibrosis activity in various scar formation and fibrosis models of many organs. However, the preventive effect of decorin on epidural fibrosis and epidural adhesions requires further investigation. Here, we investigated the therapeutic effects and potential mechanisms of decorin on epidural fibrosis and epidural adhesions. Our results indicated that decorin could significantly suppress the TGF-β1-induced proliferation, transdifferentiation, and extracellular matrix production in primary fibroblasts. Furthermore, Smad2/3 signaling pathway had been demonstrated to be involved in the preventive effect of decorin. Moreover, administration of decorin in vivo could notably inhibit epidural fibrosis and epidural adhesions after laminectomy. To date, there is no approved therapy to target TGF-β1 for the treatment of epidural fibrosis and epidural adhesions after laminectomy. Our research proved the anti-fibrosis effect of decorin, which may provide an effective and promising treatment for epidural fibrosis and epidural adhesions.

Metformin attenuates post-epidural fibrosis by inhibiting the TGF-β1/Smad3 and HMGB1/TLR4 signaling pathways

Excessive post‐epidural fibrosis is a common cause of recurrent back pain after spinal surgery. Though various treatment methods have been conducted, the safe and effective drug for alleviating post‐epidural fibrosis remains largely unknown. Metformin, a medicine used in the treatment of type 2 diabetes, has been noted to relieve fibrosis in various organs. In the present study, we aimed to explore the roles and mechanisms of metformin in scar formation in a mouse model of laminectomy. Post‐epidural fibrosis developed in a mouse model of laminectomy by spinous process and the T12‐L2 vertebral plate with a rongeur. With the administration of metformin, post‐epidural fibrosis was reduced, accompanied with decreased collagen and fibronectin in the scar tissues. Mechanistically, metformin decreased fibronectin and collagen deposition in fibroblast cells, and this effect was dependent on the HMGB1/TLR4 and TGF‐β1/Smad3 signalling pathways. In addition, metformin influenced the metabolomics of the fibroblast cells. Taken together, our study suggests that metformin may be a potential option to mitigate epidural fibrosis after laminectomy.

Honokiol protects against epidural fibrosis by inhibiting fibroblast proliferation and extracellular matrix overproduction in rats post‑laminectomy

Epidural fibrosis (EF)‑induced failed back surgery syndrome (FBSS) in patients post‑laminectomy remains a medical challenge. Although the scarring mechanisms remain unclear, the majority of aetiological studies have reported fibroblast dysfunction. Honokiol, the major bioactive constituent of the magnolia tree, exerts a variety of pharmacological effects, including anti‑proliferative and anti‑fibrotic effects, on various cell types. The present study investigated whether honokiol attenuates EF progression. In vitro, it was found that honokiol inhibited excessive fibroblast proliferation induced by transforming growth factor‑β1 (TGF‑β1) and the synthesis of extracellular matrix (ECM) components, including fibronectin and type I collagen, in a dose‑dependent manner. These effects were attributed to the ability of honokiol to suppress the activity of connective tissue growth factor (CTGF), which is indispensable for the progression of fibrosis. Mechanistically, honokiol attenuated the TGF‑β1‑induced activation of the Smad2/3 and mitogen‑activated protein kinase (MAPK) signalling pathways in fibroblasts. In vivo, honokiol reduced the proliferation of fibroblasts and the synthesis of ECM components, thus ameliorating EF in a rat model post‑laminectomy. Taken together, these preclinical findings suggest that honokiol deserves further consideration as a candidate therapeutic agent for EF.

[Comparison of different methods for drug delivery via the lumbar spinal subarachnoid space in rats]

OBJECTIVE

To compare 3 commonly used methods for drug delivery via the lumbar spinal subarachnoid space in rats.

METHODS

We compared the effects of 3 methods for drug delivery via the lumbar spinal subarachnoid space in Sprague Dawley rats, namely acute needle puncture, chronic catheterization via laminectomy, and non-laminectomized catheterization. Body weight changes of the rats were measured, and their general and neurological conditions were assessed after the surgeries. The motor function of the rats was examined using rota rod test both before and after the surgeries. Nociceptive tests were performed to assess nociception of the rats. HE staining was used to examine local inflammation caused by the surgeries in the lumbar spinal cord tissue, and lidocaine paralysis detection and toluidine blue dye assay were used to confirm the precision of drug delivery using the 3 methods.

RESULTS

Both needle puncture and catheterization via laminectomy resulted in a relatively low success rate of surgery and caused neurological abnormalities, severe motor dysfunction, hyperalgesia, allodynia and local inflammation. Catheterization without laminectomy had the highest success rate of surgery, and induced only mild agitation, slight cerebral spinal fluid leakage, mild sensory and motor abnormalities, and minimum pathology in the lumbar spinal cord. Catheterization without laminectomy produced less detectable effects on the behaviors in the rats and was well tolerated compared to the other two methods with also higher precision of drug delivery.

CONCLUSIONS

Catheterization without laminectomy is a safe, accurate and effective approach to lumbar drug delivery in rats.

Prospective application of stem cells to prevent post-operative skeletal fibrosis

Post-operative skeletal fibrosis is considered one of the major complications causing dysfunction of the skeletal system and compromising the outcomes of clinical treatment. Limited success has been achieved using current therapies; more effective therapies to reduce post-operative skeletal fibrosis are needed. Stem cells possess the ability to repair and regenerate damaged tissue. Numerous studies show that stem cells serve as a promising therapeutic approach for fibrotic diseases in tissues other than the skeletal system by inhibiting the inflammatory response and secreting favorable cytokines through activating specific signaling pathways, acting as so-called medicinal signaling cells. In this review, current therapies are summarized for post-operative skeletal fibrosis. Given that stem cells are used as a promising therapeutic approach for fibrotic diseases, little effort has been undertaken to use stem cells to prevent post-operative skeletal fibrosis. This review aims at providing useful information for the potential application of stem cells in preventing post-operative skeletal fibrosis in the near future. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1236-1245, 2019.

Schisandrin B attenuates epidural fibrosis in postlaminectomy rats by inhibiting proliferation and extracellular matrix production of fibroblasts

Laminectomy has been widely considered one of the most common treatments for lumbar disorders. Epidural fibrosis (EF) is a common complication after laminectomy, causing recurrent postoperative pain. Schisandrin B (Sch.B), the active ingredient extracted from Schisandra chinensis Fructus, has been found to have potent antiproliferative and antifibrotic effects on several cells. This study aimed to investigate the effects of Sch.B on the prevention of postlaminectomy EF formation. In vitro, we studied the effects of Sch.B on transforming growth factor beta 1 (TGF-β1)-induced proliferation and extracellular matrix (ECM) production of primary fibroblasts, as well as its underlying mechanism. We found that Sch.B not only inhibited the proliferation of fibroblasts but also reduced ECM production, including that of connective tissue growth factor, fibronectin, and type I collagen, in a dose-dependent manner. Mechanistically, we found that Sch.B suppressed TGF-β1-stimulated activation of the Smad2/3 and mitogen-activated protein kinase pathways. Moreover, the in vivo study demonstrated that Sch.B treatment attenuated the progression of EF in a postlaminectomy rat model via reducing the cell number and ECM production of scar tissue. Taken together, these data suggested that Sch.B possesses great potential value as a preventative agent for EF.

Tacrolimus induces fibroblasts apoptosis and reduces epidural fibrosis by regulating miR-429 and its target of RhoE

Tacrolimus (FK506) has been demonstrated to reduce epidural fibrosis. However, the detailed mechanism of action has not been elucidated. Aberrant miR-429 is involved in many diseases. The aim of this study was to describe the exact mechanism of FK506 induced apoptosis in fibroblasts and the prevention of epidural fibrosis. FK506 induced fibroblast apoptosis was evaluated using CCK-8 assays, flow cytometry, and western blotting. The expression of miR-429 in fibroblasts treated with FK506 was determined by RT-qPCR. Additionally, luciferase activity assays were used to determine the target relationship between miR-429 and RhoE. Flow cytometry and western blot analysis were used to determine the effects of FK506 and miR-429 on fibroblast apoptosis. The effects of FK506 and RhoE on fibroblast apoptosis were determined by CCK-8 assay, flow cytometry, and western blotting. We also evaluate the effects of FK506 and miR-429 on epidural fibrosis in rats by using histological analysis and TUNEL-staining. The results revealed FK506 induces fibroblast apoptosis and significantly downregulates miR-429 expression in fibroblasts. Additionally, miR-429 downregulation caused the apoptosis of fibroblasts. The luciferase activity assay confirmed that RhoE is a direct target of miR-429 and RhoE promotes fibroblast apoptosis. The rat model demonstrated miR-429 inhibition promotes fibroblast apoptosis and epidural fibrosis, which is consistent with the results of FK506 treatment. Our study demonstrates that FK506 induces fibroblast apoptosis and reduces epidural fibrosis by regulating miR-429 expression and its target of RhoE.

Is the use of hemostatic matrix (Floseal) and alkylene oxide copolymer (Ostene) safe in spinal laminectomies? Peridural fibrosis assessment

Objective

Failed Back Syndrome (FBS) is unacceptable relief of pain or recurrence of symptoms in patients after spinal surgery, such as laminectomy. One possible cause of FBS is peridural fibrosis (PF). PF is the overproduction of scar tissue adjacent to the dura mater. Bleeding can cause PF after laminectomy. Ostene is an alkylene oxide copolymer material used to stop bleeding from bony surfaces. Floseal is a gelatin thrombin matrix sealant used to assist fibrin formation and to promote coagulation.

Methods

Total of 32 female Sprague–Dawley rats were evenly allotted to 4 experimental groups: laminectomy only, laminectomy + Ostene (Baxter International, Inc., Deerfield, IL, USA), laminectomy + Floseal (Baxter International, Inc., Deerfield, IL, USA), and laminectomy + Adcon-L (aap Implantate AG, Berlin, Germany). After performing total laminectomy, agents were placed over dura mater. Spinal column of test subjects was harvested 6 weeks after laminectomy. Histopathological examination of samples was based on Masson's trichrome and hematoxylin and eosin staining. PF observed in the groups was graded using system previously described by He et al. Statistically significant p value was defined as p < 0.005.

Results

Present study revealed that Adcon-L, Ostene, and Floseal groups had reduced PF compared with laminectomy only group (p = 0.001). Comparison of Ostene and Floseal groups with Adcon-L group yielded no significant difference.

Conclusion

Reoperation as result of FBS has greater risk and often has poor outcome; surgeons must take precautions to avoid FBS, such as careful selection of appropriate patient and operation technique. Ostene and Floseal may be applied and left in the operation field safely during laminectomy to reduce occurrence of PF after procedure.

Local application of rapamycin reduces epidural fibrosis after laminectomy via inhibiting fibroblast proliferation and prompting apoptosis

Background

Epidural fibrosis is a common complication after laminectomy. It is associated with intractable lower back pain and additional complications. To date, no study has evaluated whether the local application of rapamycin (RAPA) can inhibit fibroblast proliferation and reduce epidural scar adhesion after laminectomy. The results of the present study showed that the local application of RAPA reduces epidural fibrosis after laminectomy in rats.

Methods

In this study, 32 male Sprague-Dawley rats were randomly divided into four groups (0.2 mg/ml RAPA-treated group, 0.1 mg/ml RAPA-treated group, 0.05 mg/ml RAPA-treated group and physiological saline group). Laminectomy was performed at the level of lumbar segment 1 to 2, and different concentrations of RAPA or saline were applied to the laminectomy sites for 10 min. Four weeks after laminectomy, the rats were sacrificed, and the degrees of epidural adhesion in each group were evaluated. Macroscopic assessment, analysis of hydroxyproline content, and histological analysis were used to determine the therapeutic effect of the local application of RAPA on the inhibition of fibroblast proliferation and the reduction of epidural fibrosis after laminectomy. Next, we cultured fibroblasts from epidural scar tissues of rats that had undergone laminectomy. Fibroblasts were exposed to the indicated concentrations of RAPA, and western blotting and TUNEL assays were used to assess the effects of RAPA on inhibiting fibroblasts proliferation and promoting fibroblast apoptosis.

Results

The results of macroscopic assessments, analysis of hydroxyproline content, and histological analyses indicated that RAPA significantly inhibited fibroblast proliferation and reduced epidural fibrosis in the treated groups in the rat model. The western blotting results indicated that the expression levels of the pro-apoptotic proteins cleaved-PARP and Bax were up-regulated, whereas those of Bcl-2 were reduced. TUNEL assay indicated that the apoptosis rates of fibroblasts were significantly increased after exposure to the indicated concentrations of RAPA.

Conclusions

The local application of RAPA reduced epidural fibrosis after laminectomy by inhibiting the proliferation of fibroblasts, stimulating their apoptosis, and decreasing collagen synthesis. This protocol may be used in new clinical treatment strategies to reduce epidural fibrosis after laminectomy.

CCN2 and CCN5 exerts opposing effect on fibroblast proliferation and transdifferentiation induced by TGF-β

Epidural fibrosis might occur after lumbar discectomy and contributes to failed back syndrome. Transforming growth factor (TGF)-β has been reported to influence multiple organ fibrosis, in which connective tissue growth factor/cysteine-rich 61/nephroblastoma overexpressed 2 (CCN2) and CCN5 are involved. However, the effect of CCN2 and CCN5 on TGF-β induced fibrosis has not yet been elucidated. This study reports that CCN2 and CCN5 play opposing roles in cell proliferation and transdifferentiation of human skin fibroblasts or rabbit epidural scar-derived fibroblasts exposed to TGF-β. We observed that TGF-β1 induced fibroblasts proliferation and differentiation in a dose-dependent manner (from 0 μg/L to 20 μg/L). Meanwhile, CCN2 expression is up-regulated while CCN5 expression is inhibited by TGF-β1 exposure. Furthermore, it is demonstrated that CCN2 overexpression leads to promoted proliferation and elevated collagen and α-smooth muscle actin (α-SMA) expression, which are inhibited by CCN5 overexpression. Moreover, it is shown that the cysteine knot (CT) domain, present in CCN2 but absent in CCN5, plays an essential part in fibroblast proliferation and differentiation. Additionally, enhanced TGF-β and CCN2 expression but decreased CCN5 expression is found in rabbit epidural scar-derived fibroblasts. Overall, the results show the opposing effects of CCN2 and CCN5 on fibroblast proliferation and transdifferentiation induced by TGF-β.

Evaluation of topical application and systemic administration of rosuvastatin in preventing epidural fibrosis in rats

BACKGROUND CONTEXT

Epidural fibrosis is a major challenge in spine surgery, with some patients having recurrent symptoms secondary to excessive formation of scar tissue resulting in neurologic compression. One of the most important factors initiating the epidural fibrosis is assumed to be the transforming growth factor-1β (TGF-1β). Rosuvastatin (ROS) has shown to demonstrate preventive effects over fibrosis via inhibiting the TGF-1β.

PURPOSE

We hypothesized that ROS might have preventive effects over epidural fibrosis through the inhibition of TGF-1β pathways.

STUDY DESIGN

Experimental animal study.

METHODS

Forty-eight adult male Wistar Albino rats were equally and randomly divided into four groups (laminectomy, spongostan, topical ROS, and systemic ROS). Laminectomy was performed at the L3 level in all rats. Four weeks later, the extent of epidural fibrosis was assessed both macroscopically and histopathologically.

RESULTS

Our data revealed that topical application and systemic administration of ROS both were effective in reducing epidural fibrosis formation. Furthermore, the systemic administration of ROS yielded better results than topical application.

CONCLUSIONS

Both topical application and systemic administration of ROS show meaningful preventive effects over epidural fibrosis through multiple mechanisms. The results of our study provide the first experimental evidence of the preventive effects of ROS over epidural fibrosis.

All-trans retinoic acid prevents epidural fibrosis through NF-κB signaling pathway in post-laminectomy rats

Laminectomy is a widely accepted treatment for lumbar disorders, and epidural fibrosis (EF) is a common complication. EF is thought to cause post-operative pain recurrence after laminectomy or discectomy. All-trans retinoic acid (ATRA) has shown anti-fibrotic, anti-inflammatory, and anti-proliferative functions. The object of this study was to investigate the effects of ATRA on the prevention of EF in post-laminectomy rats. In vitro, the anti-fibrotic effect of ATRA was demonstrated with cultured fibroblasts count, which comprised of those that were cultured with/without ATRA. In vivo, rats underwent laminectomy at the L1-L2 levels. We first demonstrated the beneficial effects using 0.05% ATRA compared to vehicle (control group). We found that a higher concentration of ATRA (0.1%) achieved dose-dependent results. Hydroxyproline content, Rydell score, vimentin-positive cell density, fibroblast density, inflammatory cell density and inflammatory factor expression levels all suggested better outcomes in the 0.1% ATRA rats compared to the other three groups. Presumably, these effects involved ATRA's ability to suppress transforming growth factor (TGF-β1) and interleukin (IL)-6 which was confirmed with reverse-transcriptase polymerase chain reaction (RT-PCR). Finally we demonstrated that ATRA down-regulated nuclear factor (NF)-κB by immunohistochemistry and western blotting for p65 and inhibition of κB (IκBα), respectively. Our findings indicate that topical application of ATRA can inhibit fibroblast proliferation, decrease TGF-β1 and IL-6 expression level, and prevent epidural scar adhesion in rats. The highest concentration employed in this study (0.1%) was the most effective. ATRA suppressed EF through down-regulating NF-κB signaling, whose specific mechanism is suppression of IκB phosphorylation and proteolytic degradation.