A comparison of the effectiveness of mitomycin C and 5-fluorouracil in the prevention of peridural adhesion after laminectomy

Docosahexaenoic Acid-Infused Core-Shell Fibrous Membranes for Prevention of Epidural Adhesions

Avoiding epidural adhesion following spinal surgery can reduce clinical discomfort and complications. As the severity of epidural adhesion is positively correlated with the inflammatory response, implanting a fibrous membrane after spinal surgery, which can act as a physical barrier to prevent adhesion formation while simultaneously modulates postoperative inflammation, is a promising approach to meet clinical needs. Toward this end, we fabricated an electrospun core-shell fibrous membrane (CSFM) based on polylactic acid (PLA) and infused the fiber core region with the potent natural anti-inflammatory compound docosahexaenoic acid (DHA). The PLA/DHA CSFM can continuously deliver DHA for up to 36 days in vitro and reduce the penetration and attachment of fibroblasts. The released DHA can downregulate the gene expression of inflammatory markers (IL-6, IL-1β, and TNF-α) in fibroblasts. Following an in vivo study that implanted a CSFM in rats subjected to lumbar laminectomy, the von Frey withdrawal test indicates the PLA/DHA CSFM treatment can successfully alleviate neuropathic pain-like behaviors in the treated rats, showing 3.60 ± 0.49 g threshold weight in comparison with 1.80 ± 0.75 g for the PLA CSFM treatment and 0.57 ± 0.37 g for the untreated control on day 21 post-implantation. The histological analysis also indicates that the PLA/DHA CSFM can significantly reduce proinflammatory cytokine (TNF-α and IL-1β) protein expression at the lesion and provide anti-adhesion effects, indicating its vital role in preventing epidural fibrosis by mitigating the inflammatory response.

Organism-Inspired Antioxidant Bioadhesive with Strong Sealing Ability to Prevent Epidural Adhesion

Epidural adhesion or epidural fibrosis is the major reason for postoperative pain, which remains a clinically challenging problem. Current physical barriers fail to provide a satisfactory therapeutic outcome mainly due to their lack of adhesion, inability to prevent fluid leakage, and exhibiting limited antioxidant properties. Herein, we fabricated a cysteine-modified bioadhesive (SECAgel) with improved sealing and antioxidant properties for epidural adhesion prevention, inspired by the organism's antioxidant systems. The resulting SECAgel showed good injectability and in situ adhesion ability, effectively covering every corner of the irregular wound. Besides, it possessed efficient sealing properties (395.2 mmHg), effectively stopping blood leakage in the rabbit carotid artery transection model. The antioxidant experiments demonstrated that the SECAgel effectively scavenged various radicals and saved the cells from oxidative stress. Two animal models were used to show that the SECAgel effectively inhibited adhesion in both situations with and without cerebrospinal fluid leakage. The RNA sequencing analysis showed that SECAgel treatment effectively inhibited the expression of key genes related to adhesion development, inflammatory response, and oxidative stress. The SECAgel, together with good biocompatibility, can be a good candidate for preventing epidural adhesion in the clinic.

Chronic pain after spine surgery: Insights into pathogenesis, new treatment, and preventive therapy

Chronic pain after spine surgery (CPSS) is often characterized by intractable low back pain and/or radiating leg pain, and has been reported in 8-40% of patients that received lumbar spine surgery. We conducted a literature search of PubMed, MEDLINE/OVID with a focus on studies about the etiology and treatments of CPSS and low back pain. Our aim was to provide a narrative review that would help us better understand the pathogenesis and current treatment options for CPSS. This knowledge will aid in the development of optimal strategies for managing postoperative pain symptoms and potentially curing the underlying etiologies. Firstly, we reviewed recent advances in the mechanistic study of CPSS, illustrated both structural (e.g., fibrosis and scaring) and non-structural factors (e.g., inflammation, neuronal sensitization, glial activation, psychological factor) causing CPSS, and highlighted those having not been given sufficient attention as the etiology of CPSS. Secondly, we summarized clinical evidence and therapeutic perspectives of CPSS. We also presented new insights about the treatments and etiology of CPSS, in order to raise awareness of medical staff in the identification and management of this complex painful disease. Finally, we discussed potential new targets for clinical interventions of CPSS and future perspectives of mechanistic and translational research. CPSS patients often have a mixed etiology. By reviewing recent findings, the authors advocate that clinicians shall comprehensively evaluate each case to formulate a patient-specific and multi-modal pain treatment, and importantly, consider an early intraoperative intervention that may decrease the risk or even prevent the onset of CPSS.

Translational potential statement

CPSS remains difficult to treat. This review broadens our understanding of clinical therapies and underlying mechanisms of CPSS, and provides new insights which will aid in the development of novel mechanism-based therapies for not only managing the established pain symptoms but also preventing the development of CPSS.

Molecular mechanisms regulating wound repair: Evidence for paracrine signaling from corneal epithelial cells to fibroblasts and immune cells following transient epithelial cell treatment with Mitomycin C

In this paper, we use RNAseq to identify senescence and phagocytosis as key factors to understanding how mitomyin C (MMC) stimulates regenerative wound repair. We use conditioned media (CM) from untreated (CMC) and MMC treated (CMM) human and mouse corneal epithelial cells to show that corneal epithelial cells indirectly exposed to MMC secrete elevated levels of immunomodulatory proteins including IL-1α and TGFβ1 compared to cells exposed to CMC. These factors increase epithelial and macrophage phagocytosis and promote ECM turnover. IL-1α supplementation can increase phagocytosis in control epithelial cells and attenuate TGFβ1 induced αSMA expression by corneal fibroblasts. Yet, we show that epithelial cell CM contains factors besides IL-1α that regulate phagocytosis and αSMA expression by fibroblasts. Exposure to CMM also impacts the activation of bone marrow derived dendritic cells and their ability to present antigen. These in vitro studies show how a brief exposure to MMC induces corneal epithelial cells to release proteins and other factors that function in a paracrine way to enhance debris removal and enlist resident epithelial and immune cells as well as stromal fibroblasts to support regenerative and not fibrotic wound healing.

Epidural Fat Tissue Is More Effective for Scar Prevention Than Conventional Subcutaneous Fat Grafting After Laminectomy in a Mouse Model

STUDY DESIGN

Basic science study.

OBJECTIVE

The aim of this study was to examine whether epidural fat tissue (EFT) transplantation can prevent epidural adhesion after laminectomy more efficiently than subcutaneous fat tissue (SFT) transplantation.

SUMMARY OF BACKGROUND DATA

Epidural adhesion is almost inevitable after laminectomy. Although many materials have been used to prevent adhesion, none has been widely accepted. As EFT is an ectopic fat tissue located on the dura mater and there is no adhesion between EFT and the dura mater, we focused on the efficacy of EFT for adhesion prevention.

METHODS

We examined the differences in histology and gene expression between EFT and SFT of mice. We performed laminectomy at the 10th thoracic level and immediately transplanted EFT or SFT to the dura mater in mice. At 6 weeks after transplantation, we performed histological and gene expression analyses and evaluated the adhesion tenacity. In addition, we examined the characteristic differences between human EFT and SFT.

RESULTS

The adipocytes of EFT were significantly smaller than those of SFT in mice and humans. The gene expression of inflammatory cytokine and fibrosis-related factors was significantly higher in SFT than in EFT. At 6 weeks after transplantation, the percentage of the remaining fat area over the dura mater was significantly greater in the EFT group than in SFT group, and the adhesion tenacity score was significantly lower in the EFT group than that in the SFT group. An RNA sequencing analysis revealed 1921 differentially expressed genes (DEGs) between human EFT and SFT, and a Gene Ontology term associated with the inflammatory response was most highly enriched in SFT.

CONCLUSION

EFT has different molecular and histological profiles from SFT and EFT grafting is more effective for epidural adhesion prevention than conventional SFT transplantation after laminectomy in a mouse model.Level of Evidence: N/A.

Tubastatin A suppresses the proliferation of fibroblasts in epidural fibrosis through phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) signalling pathway

OBJECTIVES

This study was designed to explore the effect of tubastatin A (Tub A) on epidural fibrosis and the underlying mechanism.

METHODS

Histone deacetylase 6 (HDAC6)-overexpressed fibroblasts were constructed, and the effect of Tub A on the proliferation of activated fibroblasts was detected by Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine (EdU) and cell cycle assay. Besides, 20 Sprague-Dawley rats were subjected to animal laminectomy model construction and then randomly treated with 4% dimethyl sulfoxide (DMSO) (diluted in 0.9% saline) or Tub A (10 mg/kg/day), separately. The expression of HDAC6 and phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway-related proteins was measured in epidural fibrosis tissues.

KEY FINDINGS

HDAC6 was overexpressed in activated fibroblasts and epidural scar tissues of rat models. Cell proliferation was remarkably elevated in HDAC6-overexpressed fibroblasts, which was reflected by cell viability, EdU and flow cytometry-based cell cycle assay, and paralleled with the increased expression of phosphorylated PI3K, AKT and mTOR, which was remarkably reversed following Tub A treatment. 740Y-P activator addition significantly reversed the declined fibroblast proliferation induced by Tub A. The expressions of PI3K/AKT/mTOR pathway-related proteins were also reduced in epidural tissues in rat models with Tub A treatment.

CONCLUSION

Tub A could prevent epidural fibrosis formation by inhibiting fibroblast proliferation through mediating PI3K/AKT/mTOR pathway.

Reconstruction of Epidural Fat to Prevent Epidural Fibrosis After Laminectomy in Rabbits

Background: Laminectomy can effectively decompress the spinal cord and expand the vertebral canal. However, the fibrosis that appears may cause adherence and recompression of the spinal cord or/and nerve root, which may cause failed back syndrome (FBS) and make the reexposure process more difficult. Reconstruction of the epidural fat may be an ideal method to achieve satisfactory results. Methods: Thirty-six New Zealand rabbits were randomly divided into three groups: control, extracellular matrix (ECM), and ECM+aMSCs groups. Saline, ECM gel, and ECM+aMSC complex were placed, respectively, at the fifth lumbar vertebrate of the rabbits. Epidural fat and fibrosis formation were detected by magnetic resonance imaging (MRI) and histologically at the 4th, 8th, and 12th weeks. Quantitative RT-PCR was used to detect the expression of interleukin 6 (IL-6) and transforming growth factor β (TGF-β). Results: MRI and Oil Red O staining revealed epidural fat formation at the 12th week in the ECM+aMSCs group. Hematoxylin and eosin staining showed that the numbers of fibroblasts in the ECM gel and ECM+aMSCs groups were less than the control group at the 4th and 8th weeks (p < 0.05). Masson's trichrome staining showed that the proportion of collagen fibers in the ECM gel and ECM+aMSCs group was lower than the control group (p < 0.05). Quantitative RT-PCR showed the expressions of TGF-β and IL-6 were lower in the ECM gel and ECM+aMSCs group than those in the control group (p < 0.05) at the 4th week, but higher at the 8th week. Conclusion: We successfully reconstructed the epidural fat with ECM gel and aMSC complex; additionally, IL-6 and TGF-β cytokines were lower at early stage after laminectomy.

Signalling and putative therapeutic molecules on the regulation of synoviocyte signalling in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by symmetrical and chronic polyarthritis. Fibroblast-like synoviocytes are mainly involved in joint inflammation and cartilage and bone destruction by inflammatory cytokines and matrix-degrading enzymes in RA. Approaches that induce various cellular growth alterations of synoviocytes are considered as potential strategies for treating RA. However, since synoviocytes play a critical role in RA, the mechanism and hyperplastic modulation of synoviocytes and their motility need to be addressed. In this review, we focus on the alteration of synoviocyte signalling and cell fate provided by signalling proteins, various antioxidant molecules, enzymes, compounds, clinical candidates, to understand the pathology of the synoviocytes, and finally to achieve developed therapeutic strategies of RA.

Cite this article: Bone Joint Res 2021;10(4):285–297.

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.

The Preventive Effect of Curcumin on the Experimental Rat Epidural Fibrosis Model

OBJECTIVE

The aim of the study was to evaluate the effect of systemically administrated curcumin on the prevention of peridural fibrotic tissue and adhesion formation in a rat laminectomy model.

METHODS

Thirty-two Wistar albino rats were randomly selected and equally divided into 4 groups as follows: negative control group (group I) did not undergo operation; positive control group (group II) underwent laminectomy without treatment; group III (low-dose curcumin; 100 mg/kg); and group IV (high-dose curcumin; 200 mg/kg). Curcumin was administered intraperitoneally per day for 7 days after surgery starting from day 0. Twenty-eight days after surgery, T12 and L4 vertebral columns, paraspinal tissues, and epidural scar tissue were dissected en bloc and prepared for histopathologic examinations. All specimens were examined for inflammation, epidural fibrosis (EF), foreign body reaction, medulla spinalis retraction, granulation tissue, and arachnoid involvement. A Kruskal-Wallis test followed by a Dunn multiple comparison test were used for statistical analysis, and a P value <0.05 was considered as statistically significant.

RESULTS

Curcumin treatment significantly reduced inflammation, foreign body reaction, granulation tissue formation, medulla spinalis retraction, and EF formation compared with positive control group (P < 0.05); however, no significant differences were found between the 2 groups that received different doses of curcumin.

CONCLUSIONS

The results of the present study showed that systemic administration of curcumin was effective in reducing EF formation, inflammation, granulation tissue formation, medulla spinalis retraction, and foreign body reaction in the laminectomy area. Our results suggest that antiinflammatory activities of curcumin are beneficial for attenuation of EF formation.

Multifunctional Supramolecular Hydrogel for Prevention of Epidural Adhesion after Laminectomy

Postoperative epidural adhesion remains a clinically challenging problem in spine surgery. Currently there are no effective and safe antifibrotic and antiadhesion biomaterials that have been specifically developed for this complication in clinical practice. Herein we designed and engineered an advanced antiadhesion hydrogel with multiple functionalities, including temperature-responsive gelation, self-healing, tissue adhesiveness, antioxidation, anti-inflammation, and antifibrosis. This multifunctional supramolecular hydrogel can be facilely constructed by integrating three functional modules, i.e., a thermosensitive triblock copolymer, poloxamer 407 (PX); a reactive oxygen species-eliminating and anti-inflammatory nanoparticle (TPCD NP); and an adhesion-enhancing compound, tannic acid (TA). The optimal formulation (PXNT) was hierarchically screened based on in vitro properties and in vivo activities. Therapeutically, local treatment with PXNT hydrogel effectively prevented epidural fibrosis and adhesion after laminectomy in both rats and rabbits. Of note, PXNT hydrogel showed more beneficial efficacy than different control thermosensitive hydrogels and a commercially available barrier product, Interceed. Mechanistically, PXNT hydrogel significantly attenuated local oxidative stress, inhibited inflammatory responses, and reduced fibrotic tissue formation. Moreover, treatment with PXNT hydrogel did not cause systemic adverse effects and neurological symptoms. Consequently, PXNT hydrogel is a highly promising biomaterial for preventing postlaminectomy epidural adhesion and adhesions after other surgeries.

Laminin α5 modulates fibroblast proliferation in epidural fibrosis through the PI3K/AKT/mTOR signaling pathway

Lumbar laminectomy is commonly deemed as the most valid surgery for a series of lumbar illnesses, such as lumbar disc herniation, which could lead to spinal canal stenosis. However, epidural fibrosis is one of the most common complications that limits the application of lumbar laminectomy, which is mainly caused by proliferation of local fibroblasts. Laminins are glycoproteins that consist of α, β and γ chains, which serve a crucial role in biological cell behaviors, such as adhesion, differentiation, migration and proliferation, especially the isoform with the fifth α chain-laminin α5. The PI3K/AKT/mTOR signaling pathway was demonstrated to be associated with various biological functions in cells. The aim of the present study was to explore whether laminin α5 is an important factor in epidural fibrosis by modulating the proliferation of fibroblasts through the activation of PI3K/AKT/mTOR signaling pathway. In the animal model, the results of the hematoxylin-eosin staining, cell counting, Masson's trichrome staining and immunohistochemical staining showed laminin α5 to be positively associated with epidural fibrosis. Furthermore, to verify the assumption that laminin α5 could modulate fibroblast proliferation through the PI3K/AKT/mTOR signal pathway, fibroblasts were transfected with laminin α5-small interfering (si)RNA. The results of western blotting (proliferating cell nuclear antigen and cyclin D1), the Cell Counting Kit-8 and EdU incorporation assays indicated that the proliferative level of fibroblasts decreased, and the expression of phosphorylated (p)-focal adhesion kinase 1, p-AKT and p-mTOR was reduced. Subsequently, laminin α5 was overexpressed and the change in cell proliferation and expression of associated proteins contrasted with that observed in siRNA. The results demonstrated that laminin α5 could interfere the activation of the PI3K/AKT/mTOR signaling pathway. Finally, the inhibition of the PI3K/AKT/mTOR signaling pathway by LY294002 resulted in decreased fibroblast proliferation. In conclusion, laminin α5 could modulate fibroblast proliferation in epidural fibrosis through the PI3K/AKT/mTOR signaling pathway.

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.

Artesunate inhibits fibroblasts proliferation and reduces surgery-induced epidural fibrosis via the autophagy-mediated p53/p21waf1/cip1 pathway

Fibroblast proliferation is considered to be a major cause in the process of epidural fibrosis formation. Autophagy is a tightly-regulated catabolic process in charge of degrading intracellular components. Although autophagy has been associated with fibrosis of different tissues, the effect of autophagy on epidural fibrosis is still unknown. The aim of this study was to investigate the function and mechanism of autophagy induced by Artesunate (ART), a classical antimalarial agent extracted from the Chinese medicinal herb. In vitro, the effect of ART on inducing fibroblast autophagy was evaluated via LC3 immunofluorescent staining, Transmission Electron Microscopy (TEM) and western blotting analysis. Moreover, the effect of ART on inhibiting fibroblast proliferation was investigated by CCK-8 assay, EdU incorporation assay, flow cytometry and western blotting analysis. Results indicated that ART could induce autophagy and inhibit proliferation in fibroblasts. The inhibitory effect of ART on fibroblast proliferation was associated with the upregulation of p53 and p21^waf1/cip1 proteins. Intriguingly, 3-MA, a classical autophagy inhibitor, attenuated ART-induced p53/p21^waf1/cip1 pathway activation and fibroblast proliferation inhibition. In vivo, the effect of ART on reducing epidural fibrosis was detected by histological macroscopic assessment, hydroxyproline content analysis, histological and immunohistochemical staining. The results revealed that ART had significant suppressive effects on epidural fibrosis following laminectomy in rats. In conclusion, this research demonstrated that ART could inhibit fibroblast proliferation and reduce epidural fibrosis formation after laminectomy, and the potential mechanism might through autophagy cascade-mediated p53/p21^waf1/cip1 pathway. It might provide a novel reagent for reducing epidural fibrosis after spinal laminectomy surgery.

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.

Application of a Novel Anti-Adhesive Membrane, E8002, in a Rat Laminectomy Model

Neuropathic pain after spinal surgery, so-called failed back surgery syndrome, is a frequently observed common complication. One cause of the pain is scar tissue formation, observed as post-surgical epidural adhesions. These adhesions may compress surrounding spinal nerves, resulting in pain, even after successful spinal surgery. E8002 is an anti-adhesive membrane. In Japan, a clinical trial of E8002 is currently ongoing in patients undergoing abdominal surgery. However, animal experiments have not been performed for E8002 in spinal surgery. We assessed the anti-adhesive effect of E8002 in a rat laminectomy model. The dura matter was covered with an E8002 membrane or left uncovered as a control. Neurological evaluations and histopathological findings were compared at six weeks postoperatively. Histopathological analyses were performed by hematoxylin–eosin and aldehyde fuchsin-Masson Goldner staining. Three assessment areas were selected at the middle and margins of the laminectomy sites, and the numbers of fibroblasts and inflammatory cells were counted. Blinded histopathological evaluation revealed that adhesions and scar formation were reduced in the E8002 group compared with the control group. The E8002 group had significantly lower numbers of fibroblasts and inflammatory cells than the control group. The present results indicate that E8002 can prevent epidural scar adhesions after laminectomy.

Update on biomaterials for prevention of epidural adhesion after lumbar laminectomy

Lumbar laminectomy often results in failed back surgery syndrome. Most scholars support the three-dimensional theory of adhesion: Fibrosis surrounding the epidural tissues is based on the injured sacrospinalis behind, fibrous rings and posterior longitudinal ligaments. Approaches including using the minimally invasive technique, drugs, biomaterial and nonbiomaterial barriers to prevent the postoperative epidural adhesion were intensively investigated. Nevertheless, the results are far from satisfactory. Our review is based on various implant biomaterials that are used in clinical applications or are under study. We show the advantages and disadvantages of each method. The summary will help us to figure out ideas towards new techniques. The translational potential of this article: This review summarises recent biomaterials-related clinical and basic research that focuses on prevention of epidural adhesion after lumbar laminectomy. We also propose a novel possible translational method where a soft scaffold acts as a physical barrier in the early stage, engineered adipose tissue acts as a biobarrier in the later stage in the application of biomaterials and adipose-derived mesenchymal stem cells are used for prevention of epidural adhesion.

MMC controlled-release membranes attenuate epidural scar formation in rat models after laminectomy

Epidural scar formation after laminectomy impede surgical outcomes of decompression. Mitomycin C (MMC) has been demonstrated to have significant inhibitory effects on epidural scar. This study was undertaken to develop an effective MMC controlled-release membrane and to investigate its effects on epidural scar in rat models of laminectomy. A total of 72 rats that underwent laminectomy were divided into three groups. Among them, 24 were treated with mitomycin C-polylactic acid (MMC-PLA) controlled-release membrane, 24 with mitomycin C-polyethylene glycol (MMC-PEG) controlled-release membrane, and no treatment was performed for the remaining 24 rats (control group). In the following 4 weeks, magnetic resonance image (MRI), macroscopic observation, histology and hydroxyproline (Hyp) concentration analysis were performed to explore the effects of these three therapies on epidural scar. MRI revealed a significant reduction of epidural fibrosis in MMC-PLA and MMC-PEG treatment groups, compared with the control group. Histological results also showed that collagen deposition was significantly reduced after being treated with MMC-PLA or MMC-PEG membranes. Likewise, Hyp concentrations of the epidural scar tissue in MMC-PLA and MMC-PEG groups were markedly lower than those in the control group. However, regarding the effects on reducing epidural scar, no significant difference was found between the MMC-PLA and MMC-PEG groups. In conclusion, MMC-PLA and MMC-PEG membranes are safe and effective in reducing fibrosis. Thus, MMC-controlled-release membranes promises to be a potential therapeutic in preventing epidural scar formation after laminectomy.

Upregulation of NOXA by 10-Hydroxycamptothecin plays a key role in inducing fibroblasts apoptosis and reducing epidural fibrosis

The fibrosis that develops following laminectomy or discectomy often causes serious complications, and the proliferation of fibroblasts is thought to be the major cause of epidural fibrosis. 10-Hydroxycamptothecin (HCPT) has been proven to be efficient in preventing epidural fibrosis, but the exact mechanism is still unclear. NOXA is a significant regulator of cell apoptosis, which has been reported to be beneficial in the treatment of fibrosis. We performed a series of experiments, both in vitro and in vivo, to explore the intrinsic mechanism of HCPT that underlies the induction of apoptosis in fibroblasts, and also to investigate whether HCPT has positive effects on epidural fibrosis following laminectomy in rats. Fibroblasts were cultured in vitro and stimulated by varying concentrations of HCPT (0, 1, 2, 4 µg/ml) for various durations (0, 24, 48, 72 h); the effect of HCPT in inducing the apoptosis of fibroblasts was investigated via Western blots and TUNEL assay. Our results showed that HCPT could induce apoptosis in fibroblasts and up-regulate the expression of NOXA. Following the knockdown of NOXA in fibroblasts, the results of Western blot analysis showed that the level of apoptotic markers, such as cleaved-PARP and Bax, was decreased. The results from the TUNEL assay also showed a decreased rate of apoptosis in NOXA-knocked down fibroblasts. For the in vivo studies, we performed a laminectomy at the L1-L2 levels in rats and applied HCPT of different concentrations (0.2, 0.1, 0.05 mg/ml and saline) locally; the macroscopic histological assessment, hydroxyproline content analysis and histological staining were performed to evaluate the effect of HCPT on reducing epidural fibrosis. The TUNEL assay in epidural tissues showed that HCPT could obviously induce apoptosis in fibroblasts in a dose-dependent manner. Also, immunohistochemical staining showed that the expression of NOXA increased as the concentrations of HCPT increased. Our findings are the first to demonstrate that upregulation of NOXA by HCPT plays a key role in inducing fibroblast apoptosis and in reducing epidural fibrosis. These findings might provide a potential therapeutic target for preventing epidural fibrosis following laminectomy.

Mitomycin C induces apoptosis in human epidural scar fibroblasts after surgical decompression for spinal cord injury

Numerous studies have shown that topical application of mitomycin C after surgical decompression effectively reduces scar adhesion. However, the underlying mechanisms remain unclear. In this study, we investigated the effect of mitomycin C on the proliferation and apoptosis of human epidural scar fibroblasts. Human epidural scar fibroblasts were treated with various concentrations of mitomycin C (1, 5, 10, 20, 40 μg/mL) for 12, 24 and 48 hours. Mitomycin C suppressed the growth of these cells in a dose- and time-dependent manner. Mitomycin C upregulated the expression levels of Fas, DR4, DR5, cleaved caspase-8/9, Bax, Bim and cleaved caspase-3 proteins, and it downregulated Bcl-2 and Bcl-xL expression. In addition, inhibitors of caspase-8 and caspase-9 (Z-IETD-FMK and Z-LEHD-FMK, respectively) did not fully inhibit mitomycin C-induced apoptosis. Furthermore, mitomycin C induced endoplasmic reticulum stress by increasing the expression of glucose-regulated protein 78, CAAT/enhancer-binding protein homologous protein (CHOP) and caspase-4 in a dose-dependent manner. Salubrinal significantly inhibited the mitomycin C-induced cell viability loss and apoptosis, and these effects were accompanied by a reduction in CHOP expression. Our results support the hypothesis that mitomycin C induces human epidural scar fibroblast apoptosis, at least in part, via the endoplasmic reticulum stress pathway.

Anti-adhesive effect of poloxamer-based thermo-sensitive sol-gel in rabbit laminectomy model

Poloxamer-based thermo-sensitive sol-gel has been developed to reduce the incidence of postoperative scar formation at the laminectomy site. The purpose of this study was to evaluate the anti-adhesive effect of poloxamer based thermo-sensitive sol-gel compared to hyaluronate based solution after laminectomy, using a rabbit model. A thermo-sensitive anti-adhesive with a property of sol-gel transition was manufactured by a physical mixture of Poloxamer188/407, Chitosan and Gelatin. The viscosity in different temperatures was assessed. 72 adult New Zealand rabbits underwent lumbar laminectomy and were randomly divided into experimental (treated with the newly developed agent), positive (treated with hyaluronate based solution), and negative control groups. Each group was subdivided into 1 and 4-week subgroups. Gross and histological evaluations were performed to assess the extent of epidural adhesion. The experimental group showed significantly higher viscosity compared to the positive control group and showed a significant increase of viscosity as the temperature increased. Gross evaluation showed no statistically significant differences between the 1- and 4-week subgroups. However, histologic evaluation showed significant differences both in 1- and 4-week subgroups. Although the 4-week histologic results of the experimental and the positive control subgroups showed no significant difference, both subgroups revealed higher value compared to the negative control subgroup with regard to the ratio of adhesion less than 50 %. The new poloxamer based thermo-sensitive agent showed superior efficacy over the hyaluronate based agent at 1 week postoperatively. At 4 weeks postoperatively, there were no statistically significant differences between the two agents, although both showed efficacy over the sham group.

The effect of suramin on inhibiting fibroblast proliferation and preventing epidural fibrosis after laminectomy in rats

Background

Epidural fibrosis often causes serious complications in patients after lumbar laminectomy and discectomy and is associated with the proliferation of fibroblasts. Suramin is known to have an obvious inhibitory effect on the coactions of many growth factors and their receptors, but little was previously known about the effect of suramin on fibroblast proliferation and the progress of epidural fibrosis.

Methods

We illustrated the effect of suramin on cultured fibroblasts of rats with different concentrations (0, 200, 400, 600 mg/l). The proliferation of suramin-treated fibroblasts was evaluated by CCK-8 and western blot analysis. Additionally, in a rat model of laminectomy, different concentrations of suramin (100, 200, and 300 mg/ml) and saline were applied to the laminectomy sites locally. The effect of suramin on preventing epidural fibrosis was detected by the Rydell classification, hydroxyproline content, histological analysis, and collagen density analyses.

Results

The results of CCK-8 shown that suramin could significantly inhibit fibroblasts proliferation in a dose-dependent manner. The western blotting shown that the expression levels of the cell proliferation markers such as cyclin D1, cyclin E, and PCNA were down-regulated. Moreover, in a rat model, we found that suramin could reduce epidural fibrosis as well as inhibit fibroblast proliferation, and 300 mg/ml suramin had better effect.

Conclusions

Topical application of suramin could reduce epidural fibrosis after laminectomy, and the application of suramin could inhibit the proliferation of fibroblasts in rats. This study indicates that suramin is a potent antifibrotic agent that may have therapeutic potential for patients with epidural fibrosis.

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.

Reduction of intraarticular adhesion by topical application of colchicine following knee surgery in rabbits

The aim of this study was to investigate the efficacy of topical application of colchicine in reducing intraarticular adhesion in rabbits. Thirty-six rabbits were randomly and equally divided into three groups. An approximately 10 × 10 mm² area of cortical bone was removed from both sides of the left femoral condyle, and the cancellous bone underneath was exposed. Cotton pads soaked with different concentrations of colchicine or saline were applied to the decorticated areas for 10 minutes. The surgical limb was fixed in a flexed position for 4 weeks postoperatively. To evaluate knee intraarticular adhesion, we performed macroscopic evaluation, histological and collagen density analyses, hydroxyproline content determination, fibroblast counting and densitometric analyses. The results showed that loose collagen tissues with little or no adhesion were present around the decorticated areas in the group treated with 0.5 mg/ml colchicine. The intraarticular adhesion score, hydroxyproline content, number of fibroblasts and densitometric value in this group were also significantly lower than those in the other groups. There was moderate intraarticular adhesion in the group treated with 0.1 mg/ml colchicine. However, dense scar tissue with dense adhesions was found in the control group. In conclusion, topical application of 0.5 mg/ml colchicine may reduce knee intraarticular adhesion.

Potential risk of mitomycin C at high concentrations on peripheral nerve structure

Although the local application of mitomycin C may prevent epidural adhesion after laminectomy, mitomycin C can induce neurotoxicity in optic and acoustic nerves at high concentrations. To determine the safe concentration range for mitomycin C, cotton pads soaked with mitomycin C at different concentrations (0.1, 0.3, 0.5, and 0.7 mg/mL) were immediately applied for 5 minutes to the operation area of rats that had undergone laminectomy at L₁. Rat sciatic nerves, instead of dorsal nerves, were used in this study. The results showed that mitomycin C at 0.1-0.5 mg/mL did not damage the structure and function of the sciatic nerve, while at 0.7 mg/mL, mitomycin C significantly reduced the thickness of the sciatic nerve myelin sheath compared with lower concentrations, though no functional change was found. These experimental findings indicate that the local application of mitomycin C at low concentrations is safe to prevent scar adhesion following laminectomy, but that mitomycin C at high concentrations (> 0.7 mg/mL) has potential safety risks to peripheral nerve structures.

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.

Publication patterns of comparative effectiveness research in spine neurosurgery

OBJECT

The purpose of this study was to investigate publication patterns for comparative effectiveness research (CER) on spine neurosurgery.

METHODS

The authors searched the PubMed database for the period 1980-2012 using the key words "cost analysis," "utility analysis," "cost-utility," "outcomes research," "practical clinical research," "comparator trial," and "comparative effectiveness research," linked with "effectiveness" and "spine neurosurgery."

RESULTS

From 1980 through April 9, 2012, neurosurgery CER publications accounted for 1.38% of worldwide CER publications (8657 of 626,330 articles). Spine neurosurgery CER accounted for only 0.02%, with 132 articles. The journal with the greatest number of publications on spine neurosurgery CER was Spine, followed by the Journal of Neurosurgery: Spine. The average annual publication rate for spine neurosurgery CER during this period was 4 articles (132 articles in 33 years), with 68 (51.52%) of the 132 articles being published within the past 5 years and a rising trend beginning in 2008. The top 3 contributing countries were the US, Turkey, and Japan, with 68, 8, and 7 articles, respectively. Only 8 regular articles (6.06%) focused on cost analysis.

CONCLUSIONS

There is a paucity of publications using CER methodology in spine neurosurgery. Few articles address the issue of cost analysis. The promotion of continuing medical education in CER methodology is warranted. Further investigations to address cost analysis in comparative effectiveness studies of spine neurosurgery are crucial to expand the application of CER in public health.

Endoplasmic reticulum stress signaling is involved in mitomycin C (MMC)-induced apoptosis in human fibroblasts via PERK pathway

Endoplasmic reticulum (ER) stress-mediated cell apoptosis has been implicated in various cell types, including fibroblasts. Previous studies have shown that mitomycin C (MMC)-induced apoptosis occurs in fibroblasts, but the effects of MMC on ER stress-mediated apoptosis in fibroblasts have not been examined. Here, MMC-induced apoptosis in human primary fibroblasts was investigated by exposing cells to a single dose of MMC for 5 minutes. Significant inhibition of cell proliferation and increased apoptosis were observed using a cell viability assay, Annexin V/propidium iodide double staining, cell cycle analysis, and TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling) staining. Upregulation of proapoptotic factors, including cleaved caspase-3 and poly ADP-ribose polymerase (PARP), was detected by Western blotting. MMC-induced apoptosis was correlated with elevation of 78-kDa glucose-regulated protein (GRP78) and C/EBP homologous protein (CHOP), which are hallmarks of ER stress. Three unfolded protein response (UPR) sensors (inositol-requiring enzyme 1, IRE1; activating transcription factor 6, ATF6; and PKR-like ER kinase, PERK) and their downstream signaling pathways were also activated. Knockdown of CHOP attenuated MMC-induced apoptosis by increasing the ratio of BCL-2/BAX and decreasing BIM expression, suggesting that ER stress is involved in MMC-induced fibroblast apoptosis. Interestingly, knockdown of PERK significantly decreased ER stress-mediated apoptosis by reducing the expression of CHOP, BIM and cleaved caspase-3. Reactive oxygen species (ROS) scavenging also decreased the expression of GRP78, phospho-PERK, CHOP, and BIM. These results demonstrate that MMC-induced apoptosis is triggered by ROS generation and PERK activation.

Comparison of the effects of mitomycin C and 10-hydroxycamptothecin on an experimental intraarticular adhesion model in rabbits

The study was to compare the preventive effects of the local application of mitomycin C (MMC) and 10-hydroxycamptothecin (HCPT) on reducing intraarticular adhesion after knee surgery in rabbit model. Thirty-six New-Zealand rabbits were randomly and equally divided into three groups: MMC, HCPT and control group. Approximately 10 mm × 10 mm of the cortical bone was removed from both sides of left femoral condyle and the cancellous bone underneath was exposed. The exposed decorticated areas were covered with cotton pads soaked with MMC (0.1mg/ml), HCPT (0.1mg/ml) and physiological saline for 10 min. The left knee joint was then fixed in the fully flexed position with a Kirschner wire for 4 weeks after surgery. The rabbits were killed after 4 weeks and multiple parameters including the macroscopic evaluation, the hydroxyproline content, the histological evaluation and the fibroblast counts were used to evaluate the effect of MMC and HCPT on preventing intraarticular adhesion. The results showed that weak fibrous adhesions were found around the decorticated areas in MMC group and moderate intraarticular adhesions were found in HCPT group. However, there were severe fibrous adhesions around the decorticated areas in control group. The hydroxyproline contents and the fibroblast numbers of MMC and HCPT group were significantly less than those of control group. In conclusion, our data showed that topical application of MMC and HCPT could prevent intraarticular adhesion after knee surgery in rabbit model, but MMC had a better preventive effect than that of HCPT.

The effect of mitomycin-C in reducing pericardial adhesion after cardiac surgery in rabbits

BACKGROUND

Mitomycin-C has been in clinical use primarily as a chemotherapeutic agent and is well known for antifibrotic properties. It has been widely used to prevent postoperative fibroblast proliferation and reduce scar adhesion in ophthalmologic and otolaryngologic operations. We investigated the efficacy of mitomycin-C in reducing postoperative pericardial adhesions in a rabbit model.

METHODS

New Zealand white rabbits were used and categorized into 2 groups, study (use of mitomycin-C) and control. Group 1 (n = 8) was treated with a sponge impregnated with mitomycin-C solution that was applied over the abraded epicardium. In group 2 (control group), the sponge was impregnated with 0.9% isotonic NaCl solution and was applied with the same protocol as the mitomycin-C-impregnated sponge in group 1 (n = 8). Rabbits were humanely killed at a mean of 2 weeks. The scores of adhesion were graded by macroscopic examination, and the pericardial tissues were analyzed microscopically in terms of inflammation and fibrosis.

RESULTS

In group 1, the adhesion scores were significantly lower than the control group's. No significant difference was found between the groups in terms of the severity of inflammation. There was a difference between groups in terms of the degree of fibrosis.

CONCLUSIONS

The use of mitomycin-C to prevent postoperative pericardial adhesions reduced adhesion and fibrosis scores in an experimental rabbit model. However, efficacy in reducing inflammation was not demonstrated.

A comparative study of the preventive effects of mitomycin C and chitosan on intraarticular adhesion after knee surgery in rabbits

We sought to compare the preventive effects of mitomycin-C(MMC) and chitosan on intraarticular adhesion after knee surgery in rabbits. For this purpose, 48 New-Zealand rabbits were randomly and equally divided into MMC, chitosan, and control groups. Approximately 10 × 10 mm(2) of the cortical bone was removed from both sides of left femoral condyle and the cancellous bone underneath was exposed. The decorticated areas were topically treated with MMC and chitosan while control group was treated with physiological saline. The lower left limb was fixed in flexed position with Kirschner-wire for 4 weeks postoperatively. After 4 weeks, gross and histopathological examination, biochemical analysis, and fibroblast counts were performed on knee intraarticular adhesion in each group. The data show mild membrane-like fibrous intraarticular adhesion, presented in loose, in MMC group. There was moderate intraarticular adhesion in chitosan group while in controls; there was large-size compact fibrous tissue adhesion. Hydroxyproline contents and fibroblast quantity of MMC and chitosan groups were lower (P < 0.05) than that of control group. We, therefore, concluded that MMC and chitosan could prevent intraarticular adhesion of the knee in rabbits by inhibiting fibroblast proliferation and reducing collagenous fiber formation while MMC had a better preventive effect than that of chitosan.

The effectiveness of poloxamer 407-based new anti-adhesive material in a laminectomy model in rats

PURPOSE

In the laminectomy model in rats, to verify anti-adhesive effectiveness of the new material, a mixture composed of poloxamer 407, calcium chloride, and xanthorrhizol, we compared it with that of commercially used solution form anti-adhesive agent GUARDIX-SL, Biorane.

MATERIALS AND METHODS

A total of 108 Sprague-Dawley rats (SD rats) were divided equally into three groups: negative control group (NCG), positive control group (PCG), and experimental group (EG). After exposing the dura on L4 level, we closed the wound shortly after hemostasis, after administering the anti-adhesive agent. To evaluate effectiveness, 18 SD rats from each group were killed after 1 week of rearing. Nine were examined by grading of gross adhesion and the other nine, by grading of histological adhesion. The degree of adhesion in the remainder of 18 SD rats in each group was examined with the same method after four weeks of rearing.

RESULTS

Comparing the degree of adhesion after growth for 1 week, the gross and histological adhesion of the EG was lower than that of the NCG. There was no statistical significance in the gross score (P = 0.63), but there was statistical significance in the histological score (P = 0.04). The EG showed similar or improved degrees of adhesion in comparison with the PCG. In comparison after growth for 4 weeks, although gross adhesion of the EG was not significantly lower than the NCG, histological adhesion was remarkably low in the EG (P = 0.01). The EG showed similar or improved degrees of gross and histological adhesion in comparison to that of the PCG. (P = 0.20, 0.07).

CONCLUSION

The new anti-adhesive material showed similar or improved effectiveness with the existing agents for commercial use. This result suggests that the new anti-adhesive material will be a successful candidate as a future product for clinical use.

Effect of topical application of mitomycin-C on wound healing in a postlaminectomy rat model: an experimental study

The aim of this study was to investigate the effects of topical application mitomycin-C (MMC) on wound healing after laminectomy. 60 adult male SD rats were equally and randomly divided into five groups. Laminectomy was performed at the level of L1 in all rats. After hemostasis was achieved, cotton pads soaked with saline and MMC (0.1mg/ml, 0.3mg/ml, 0.5mg/ml and 0.7mg/ml) were directly subjected to the exposed dura for 5min in each group. Two weeks after laminectomy all the rats were killed. The vertebral column including the back scar tissue and muscles was obtained to make paraffin sections. The hematoxylin-eosin staining and Masson staining were performed with the obtained paraffin sections. The number of the fibroblast and the capillary density were counted by the hematoxylin-eosin staining slice. The extent of epidural fibrosis and the expression of vascular endothelial growth factor (VEGF) were evaluated by the immunohistochemical slice through a computer image analysis system. Our data showed that the number of fibroblast, capillary density and fibrotic tissue in the 0.5 and 0.7mg/ml MMC groups was significantly lower than the control, 0.1 and 0.3mg/ml MMC groups; while the expression of VEGF in control and 0.1mg/ml MMC groups was notably higher than 0.3, 0.5 and 0.7mg/ml MMC groups. Topical application of MMC above the concentration of 0.3mg/ml could affect all steps of the wound healing process via inhibiting the angiogenesis and fibroblast proliferation, thus delayed the wound healing after laminectomy.

Study on the optimal concentration of topical mitomycin-C in preventing postlaminectomy epidural adhesion

There is increasing evidence that topical application of mitomycin-C can be beneficial in reducing epidural scar adhesion. However, the ideal concentration of mitomycin-C is unknown. The purpose of this study was to verify its efficacy for preventing epidural adhesion and the immediate electrophysiological responses caused by it in a laminectomy model. Seventy rats underwent laminectomy at L-1 and L-2. Cotton pads soaked with saline and various concentrations of mitomycin-C (0.1 mg/ml, 0.3 mg/ml, 0.5 mg/ml and 0.7 mg/ml) were applied to the exposed dura for 5 min. Spine somatosensory evoked potentials (SSEP) were monitored in preoperative and the immediate electrophysiological responses of mitomycin-C used. Four weeks postlaminectomy the rats were killed. The area of epidural scar tissue and degree of epidural adhesion were determined by 7.0 T Micro MR imaging. Macroscopic evaluations were performed according to the Rydell standard. The results showed that severe epidural adhesion was formed in the saline group and no dural adherence or incomplete adhesions were found in the mitomycin-C group. The Rydell classification and the degree of epidural adhesion and the area of the scar in 0.5 mg/ml group and 0.7 mg/ml mitomycin-C group revealed a significant decrease compared with the control group and 0.1 mg/ml group and 0.3 mg/ml mitomycin-C group. The spine sensory evoked potentials did not alter obviously in both preoperative and the immediate electrophysiological responses of mitomycin-C used. In conclusion, locally applied mitomycin-C in a concentration of 0.5 mg/ml and 0.7 mg/ml mitomycin-C may be the optimal concentration in preventing postlaminectomy epidural adhesion.

Mitomycin C-polyethylene glycol controlled-release film inhibits collagen secretion and induces apoptosis of fibroblasts in the early wound of a postlaminectomy rat model

BACKGROUND CONTEXT

Recovery from spine surgery is usually accompanied with the development of epidural scar adhesions from the abnormal proliferation of fibroblast and extracellular matrix-related metabolism. Polyethylene glycol (PEG) could alleviate the postsurgical adhesion formation with still leaving a gap between the sheet and the dura. However, PEG film could not function as a three-dimensional barrier to prevent adhesion completely. Mitomycin C (MMC) could also reduce the scar formation after surgery, but cytotoxicity and the administrative pathway prevent its application.

PURPOSE

Our purpose was to design and attest the role of new delivery system MMC-PEG controlled-release film in preventing the epidural scar adhesions after laminectomy in the rat model.

STUDY DESIGN/SETTING

A total laminectomy of L1 in the rat model was used to assess epidural fibrosis between and around the spinal nerves using a histochemistry assessment along with flow cytometry analysis.

PATIENT SAMPLE

The sample comprises 64 adult male Sprague-Dawley rats.

OUTCOME MEASURES

The outcome measures are macroscopic evaluation, histological analysis, and flow cytometry analysis.

METHODS

Lumbar laminectomies at L1 and L2 with a L1-L2 disc injury were performed on 64 adult male Sprague-Dawley rats. The rats were then randomized into four groups. In Group I, 25 mg PEG film was applied on the dura mater in the laminectomy area before the layers were sutured. In Group II, a cotton pad soaked with 0.05% MMC solution was kept on the laminectomy area for 5 minutes. In Group III, 25 mg PEG film containing 0.01% MMC was implanted on the laminectomy area. In Group IV, the laminectomy area was flushed with saline before wound closure. The rats were sacrificed 4 weeks after the operation. Macroscopic evaluation and histological analysis of epidural scar adhesion with the hematoxylin and eosin stain and Masson stain were used followed by the quantification of hydroxyproline (Hyp) and flow cytometry analysis of the apoptosis of fibroblasts in the scar tissues.

RESULTS

The recovery of all rats was uneventful after the operations. In the laminectomy sites of rats treated with MMC or MMC-PEG, the dura mater was clean without any evident adhesion or membrane. Collagen tissue hyperplasia significantly decreased in the MMC- or MMC-PEG-treated models. Accordingly, Hyp concentration was significantly reduced in these two groups compared with saline-control group. In addition, the apoptosis of fibroblasts, however, was significantly elevated in the MMC or MMC-PEG group compared with the saline-control group.

CONCLUSIONS

These results demonstrate that the treatment of postlaminectomy wounds with MMC-PEG film reduces the severity of adhesion by decreasing the concentration of Hyp and increasing the apoptosis of fibroblasts.