Calcium channel blockers in reduction of epidural fibrosis and dural adhesions in laminectomy rats

Postoperative Epidural Fibrosis: Challenges and Opportunities - A Review

Postoperative epidural fibrosis (EF) is still a major limitation to the success of spine surgery. Fibrotic adhesions in the epidural space, initiated via local trauma and inflammation, can induce difficult-to-treat pain and constitute the main cause of failed back surgery syndrome, which not uncommonly requires operative revision. Manifold agents and methods have been tested for EF relief in order to mitigate this longstanding health burden and its socioeconomic consequences. Although several promising strategies could be identified, few have thus far overcome the high translational hurdle, and there has been little change in standard clinical practice. Nonetheless, notable research progress in the field has put new exciting avenues on the horizon. In this review, we outline the etiology and pathogenesis of EF, portray its clinical and surgical presentation, and critically appraise current efforts and novel approaches toward enhanced prevention and treatment.

Pharmacotherapies to prevent epidural fibrosis after laminectomy: a systematic review of in vitro and in vivo animal models

BACKGROUND CONTEXT

Excessive production of epidural fibrosis in the nerve root can be a pain source after laminectomy. Pharmacotherapy is a minimally invasive treatment option to attenuate epidural fibrosis by suppressing proliferation and activation of fibroblasts, inflammation, and angiogenesis, and inducing apoptosis.

PURPOSE

We reviewed and tabulated pharmaceuticals with their respective signaling axes implicated in reducing epidural fibrosis. Additionally, we summarized current literature for the feasibility of novel biologics and microRNA to lessen epidural fibrosis.

STUDY DESIGN/SETTING

Systematic Review.

METHODS

According to the PRISMA guidelines, we systematically reviewed the literature in October 2022. The exclusion criteria included duplicates, nonrelevant articles, and insufficient detail of drug mechanism.

RESULTS

We obtained a total of 2,499 articles from PubMed and Embase databases. After screening the articles, 74 articles were finally selected for the systematic review and classified based on the functions of drugs and microRNAs which included inhibition of fibroblast proliferation and activation, pro-apoptosis, anti-inflammation, and antiangiogenesis. In addition, we summarized various pathways to prevent epidural fibrosis.

CONCLUSION

This study allows a comprehensive review of pharmacotherapies to prevent epidural fibrosis during laminectomy.

CLINICAL SIGNIFICANCE

We expect that our review would enable researchers and clinicians to better understand the mechanism of anti-fibrosis drugs for the clinical application of epidural fibrosis therapies.

Phosphodiesterase 5 Inhibitor Use in Patients Undergoing Decompression Surgery for Lumbar Spinal Stenosis

OBJECTIVE

Our objectives were to explore the association between phosphodiesterase 5 inhibitor use and lumbar decompression surgery by evaluating the prevalence of lumbar decompression surgery in a treatment group of patients with lumbar spinal stenosis compared with a control group.

DESIGN

We performed database review and extracted data including lumbar decompression surgery prevalence, phosphodiesterase 5 inhibitor dosage, and fill dates. Treatment group was defined as those with phosphodiesterase 5 inhibitor fill dates of less than 30 days before surgery, and control group was defined as those with phosphodiesterase 5 inhibitor fill dates at any other time. Lumbar decompression surgery prevalence rates for both groups were calculated.

RESULTS

Our study found 599 lumbar spinal stenosis patients who were prescribed phosphodiesterase 5 inhibitor. Three hundred thirty-eight underwent lumbar decompression surgery. Of these, 71 (21%) filled their prescription of less than 30 days before surgery, whereas 267 (79%) filled their prescription during a different period. The majority (94.6%) of surgical patients received decompression at two or more spinal levels.

CONCLUSIONS

Prevalence of lumbar decompression surgery for lumbar spinal stenosis was significantly lower in patients in the treatment group on phosphodiesterase 5 inhibitor therapy compared with the control group. Among many potential explanations, the vasodilatory effect of phosphodiesterase 5 inhibitor may have contributed to a lower surgical rate. This is the first study to explore this novel association. Future prospective studies are necessary to better define the utility of phosphodiesterase 5 inhibitor in lumbar spinal stenosis.

Intra-articular injection of mitomycin C prevents progression of immobilization-induced arthrogenic contracture in the remobilized rat knee

This study tested whether cell cycle inhibitor mitomycin C (MMC) prevents arthrogenic contracture progression during remobilization by inhibiting fibroblast proliferation and fibrosis in the joint capsule. Rat knees were immobilized in a flexed position to generate flexion contracture. After three weeks, the fixation device was removed and rat knees were allowed to freely move for one week. Immediately after and three days after fixator removal, rats received intra-articular injections of MMC or saline. The passive extension range of motion (ROM) was measured before and after myotomy of the knee flexors to distinguish myogenic and arthrogenic contractures. In addition, both cellularity and fibrosis in the posterior joint capsule were assessed histologically. Joint immobilization significantly decreased ROMs both before and after myotomy compared with untreated controls. In saline-injected knees, remobilization increased ROM before myotomy, but further decreased that after myotomy compared with that of knees immediately after three weeks of immobilization. Histological analysis revealed that hypercellularity, mainly due to fibroblast proliferation, and fibrosis characterized by increases in collagen density and joint capsule thickness occurred after remobilization in saline-injected knees. Conversely, MMC injections were able to prevent the remobilization-enhanced reduction of ROM after myotomy by inhibiting both hypercellularity and joint capsule fibrosis. Our results suggest that joint capsule fibrosis accompanied by fibroblast proliferation is a potential cause of arthrogenic contracture progression during remobilization, and that inhibiting fibroblast proliferation may constitute an effective remedy.

EFFECT OF PLATELET-RICH PLASMA, FAT PAD AND DURAL MATRIX IN PREVENTING EPIDURAL FIBROSIS

OBJECTIVE

Epidural fibrosis is one of the main reasons for requiring repeated surgical intervention. Our objective was to compare the effect of Platelet Rich Plasma (PRP) on the development of epidural fibrosis with collagen dural matrix and free autogenous fat graft.

METHODS

Male rats were separated into 3 groups. Laminectomy was implemented on the rats and epidural fat pad was placed in the first group (n = 7); equal size of collagen dural matrix was applied in the second group (n = 7); a single dose of PRP was applied in the third group (n = 7).

RESULTS

Epidural fibrosis was more common in the group that collagen dural matrix was applied when compared the ones that PRP was applied. PRP group presented better values in preventing epidural fibrosis when compared to the fat pad group, however this difference was not statistically significant.

CONCLUSION

PRP is a material that can be easily obtained from the very blood of patients and at an extremely low cost; the main clinical relevance of our study is that the PRP might be an efficient material for better clinical results after laminectomy surgery due to its tissue healing and epidural fibroris preventing potentials. Level of Evidence V, Animal research.

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.

Active exercise on immobilization-induced contractured rat knees develops arthrogenic joint contracture with pathological changes

This study investigated the effects of treadmill walking during remobilization on range of motion (ROM) and histopathology in rat knee joints, which were immobilized for 3 wk in a flexed position. After fixator removal, rats were divided into a no-intervention (RM) group and a group forced to walk on a treadmill daily at 12 m/min for 60 min (WALK group). Passive knee extension ROMs were measured before (m-ROM) and after (a-ROM) knee flexor myotomy on the first and last day of a 7-day remobilization period, with m-ROM mainly reflecting myogenic factors and a-ROM reflecting arthrogenic factors. Knee joints were histologically analyzed and gene expression of inflammatory or fibrosis-related mediators in the posterior joint capsule were examined. m-ROM and a-ROM restrictions were established after immobilization. m-ROM significantly increased following the remobilization period both in RM and WALK groups compared with that of immobilized (IM) group. Conversely, a-ROM decreased following the remobilization period in both RM and WALK groups compared with that of IM group. Importantly, a-ROM was smaller in the WALK group than the RM group. Remobilization without intervention induced inflammatory and fibrotic reactions in the posterior joint capsule after 1 and 7 days. Treadmill walking promoted these reactions and also increased the expression of fibrosis-related TGF-β1 and collagen type I and III genes. While free movement after immobilization improved myogenic contracture, arthrogenic contracture worsened. Treadmill walking further aggravated arthrogenic contracture through amplified inflammatory and fibrotic reactions. Thus active exercise immediately after immobilization may not improve immobilization-induced joint contracture.

NEW & NOTEWORTHY In clinical practice, it is widely accepted that facilitation of joint movements is effective in improving immobilization-induced joint contracture. However, whether active exercises improve arthrogenic contracture is not known. In this study, we revealed that treadmill walking further promoted remobilization-induced progression of arthrogenic contracture. To our knowledge, this is the first study demonstrating no favorable effect of active exercise on immobilization-induced arthrogenic contracture.

EFFECTIVENESS OF CREAM CONTAINING VERAPAMIL HYDROCHLORIDE, IN THE THERAPY OF RUBTS IN EXPERIMENT

The data in respect to efficacy of verapamil-containing scar cream for treatment of hypertrophic and keloid scars are presented in the article. Skin scars were simulated in rats by excision of a full-thickness skin flap size 5x4 cm2 in the center of the back. Upon wound healing and scar formation a daily twofold fomentation of verapamil-containing cream was carried out. Treatment efficacy was checked after 10, 30 and 60 days. The following indices were studied: an area of the scar, its type, consistence, color, sensitivity, and scar microcirculation according to biomicroscopy. The proposed novel method for treatment of hypertrophic and keloid scars with verapamil-containing cream allowed to obtain a sustained clinical result demonstrating a reducing area of the scar by 25%, a physiological scar formation, improving the consistence and scar colour changing to the normal skin colour, its softening and flattening, and pain disappearance. Due to the dermal application, the method was painless, safety and did not affect on the surrounding tissues. According to biomicroscopy a scar remodeling approximated the indices to the level of healthy skin in 93% of rats. The most significant clinical effect the cream with verapamil was observed in experimental animals in 60 days after treatment.

The role and mechanisms of action of SIRT6 in the suppression of postoperative epidural scar formation

In order to investigate the role which sirtuin-6 (SIRT6) plays in lumbar spinal epidural fibrosis (EF) and scar formation in vitro and in vivo, SIRT6 and transforming growth factor β (TGF‑β) protein levels in the lumbar disc of patients were detected using western blotting in patients who had undergone a laminectomy. The results demonstrated that SIRT6 expression was significantly reduced in the lumbar discs of patients in whom an epidural scar had formed, but the expression pattern of TGF-β2 was much higher. Subsequently, a pcDNA‑SIRT6 expression vector was constructed and transfected into the primary fibroblasts isolated from the epidural scars. Flow cytometric and MTT analyses indicated that overexpression of SIRT6 suppressed the proliferation of the fibroblasts, and TGF‑β2 and interleukin-1α expression, as well as collagen type I (Col I) production. The results of bioinformatics and molecular biological analyses demonstarted that TGF‑β2 was a target of microRNA-21 (miR-21) and SIRT6 overexpression suppressed the levels of TGF-β2 through promoting the expression of miR-21. Finally, by injecting the pcDNA-SIRT6 vector, it was possible to observe that SIRT6 suppressed EF and epidural scar formation in vivo. In conclusion, we noted that SIRT6 suppressed EF and epidural scar formation in vitro and in vivo. It was also noted that SIRT6 overexpression suppressed TGF-β2 levels by promoting the expression of miR-21.

Intra-articular adhesion reduction after knee surgery in rabbits by calcium channel blockers

BACKGROUND

Intra-articular adhesion post knee surgery is a common and serious complication. It is a challenge problem for orthopedic surgeon. Verapamil (VP), a widely applied calcium channel blocker, has been proved to be able to prevent synthesis/secretion of extracellular matrix molecules. The object of this study was to investigate the effects of VP on the prevention of joint adhesion in post-surgery rabbits.

MATERIAL/METHODS

A controlled double-blinded study was conducted in 40 healthy New Zealand white rabbits divided randomly into 4 groups according to the treatment method, with 10 in each group: 1) 1 mg/ml VP treatment group; 2) 2.5 mg/ml VP treatment group; 3) 5 mg/ml VP treatment group; 4) control group. Rabbits underwent surgery through the medial parapatellar approach and both lateral sides and the medial of the femoral condyle were surgically exposed. After treatment, the surgical limbs were subjected to extra-articular knee-joint immobilization in the full flexed position employing Kirschner wires for 4 weeks.

RESULTS

The knee surgery was successfully performed on all rabbits. The rabbits were killed 4 weeks post-operatively. The histological evaluation, hydroxyproline content, visual score, fibroblasts density, and vimentin expressional levels were conducted to assess the effect of VP on preventing joint adhesion.

CONCLUSIONS

In our rabbit model of knee surgery, intra-articular application of VP was able to decrease intra-articular adhesion formation after surgery. VP could prevent rabbit intra-articular adhesion in a dose-dependent manner and the highest concentration used in the study (5 mg/ml) proved to be the most effective.

Study on salvianolic acid B in the reduction of epidural fibrosis in laminectomy rats

Background

Epidural fibrosis (EF) is a common complication after laminectomy. Salvianolic acid B (Sal B) is a major bioactive component of a traditional Chinese medical agent, Salvia miltiorrhiza, which has shown anti-inflammatory, anti-fibrotic and anti-proliferative properties. The object of this study was to investigate the effect of Sal B on the prevention of epidural fibrosis in laminectomy rats.

Methods

A controlled double-blinded study was conducted in sixty healthy adult Wistar rats that underwent laminectomy at the L1-L2 levels. The rats were randomly divided into 3 groups of 20: (1) Sal B treatment group; (2) Vehicle group; (3) Sham group (laminectomy without treatment). All rats were sacrificed 4 weeks post-operatively. The extent of epidural fibrosis, fibroblast proliferation and the expression of vascular endothelial growth factor (VEGF) and inflammatory factors were analyzed.

Results

The recovery of all rats was uneventful. In the laminectomy sites treated with Sal B, the dura mater showed no adhesion. Collagen deposition was significantly lower in the Sal B group than the other two groups. In addition, both fibroblast and inflammatory cell counting in the laminectomy sites treated with Sal B showed better grades than the other two groups. The expression of VEGF and inflammatory factors in operative sites also suggested better results in the Sal B group than the other two groups.

Conclusions

Sal B inhibits fibroblast proliferation, blood vessel regeneration, and inflammatory factor expression. Thus, Sal B is able to prevent epidural scar adhesion in post-laminectomy rats.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-337) contains supplementary material, which is available to authorized users.

An experimental novel study: hyperbaric oxygen treatment on reduction of epidural fibrosis via down-regulation of collagen deposition, IL-6, and TGF-β1

OBJECTIVE

To investigate the effect of hyperbaric oxygen treatment (HBO) on prevention of epidural fibrosis in laminectomy rats.

METHODS

A controlled, double-blinded study was performed in sixty healthy adult Wistar rats, mean weight 250 g. L1-L2 levels laminectomy were performed. Randomly, all rats were divided into three groups, with 20 in each group: (1) short-term HBO treatment group; (2) long-term HBO treatment (LHBO) group; and (3) Sham group (laminectomy without treatment). Four weeks post-operation, all rats were killed. The Rydell classification, hydroxyproline content, vimentin cells density, capillary density, and inflammatory factors expression were evaluated.

RESULTS

The histological evaluation showed less epidural scar adhesions in LHBO group than other two groups. The hydroxyproline content, Rydell score, vimentin cells density, capillary density, and inflammatory factors expression all suggested better results in LHBO group than other two groups.

CONCLUSION

It was concluded that HBO treatment might be beneficial in inhibiting collagen deposition and inflammatory activity and prevent epidural scar adhesion in laminectomy rat and, therefore, shows potential for clinical use.