The role of hybrid chitosan membranes on scarring process following lumbar surgery: post-laminectomy experimental model

An injectable and antifouling hydrogel prevents the development of abdominal adhesions by inhibiting the CCL2/CCR2 interaction

Abdominal adhesion, a serious complication of abdominal surgery, often resists mitigation by current drug administration and physical barriers. To address this issue, we developed an injectable, antifouling hydrogel through the free-radical polymerization of methacrylate chondroitin sulfate (CS-GMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) monomers, dubbed the CGM hydrogel. We systematically analyzed its physicochemical properties, including rheological strength, biocompatibility, and antifouling capabilities. A rat abdominal cecum adhesion model was constructed to assess the effectiveness of CGM hydrogel in preventing postoperative adhesion and recurrent adhesion. In addition, multi-omics analyses identified the relationship between adhesion development and CCL2/CCR2 interaction. Notably, CGM hydrogel can thwart the recruitment and aggregation of fibroblasts and macrophages by inhibiting the CCL2/CCR2 interaction. Moreover, CGM hydrogel significantly dampens the activity of fibrosis-linked cytokines (TGF-βR1) and recalibrates extracellular matrix deposition-related cytokines (t-PA and PAI-1, Col Ⅰ and MMP-9). Cumulatively, the dual action of CGM hydrogel-as a physical barrier and cytokine regulator-highlights its promising potential in clinical application for abdominal adhesion prevention.

Prevention strategies of postoperative adhesion in soft tissues by applying biomaterials: Based on the mechanisms of occurrence and development of adhesions

Postoperative adhesion (POA) widely occurs in soft tissues and usually leads to chronic pain, dysfunction of adjacent organs and some acute complications, seriously reducing patients' quality of life and even being life-threatening. Except for adhesiolysis, there are few effective methods to release existing adhesion. However, it requires a second operation and inpatient care and usually triggers recurrent adhesion in a great incidence. Hence, preventing POA formation has been regarded as the most effective clinical strategy. Biomaterials have attracted great attention in preventing POA because they can act as both barriers and drug carriers. Nevertheless, even though much reported research has been demonstrated their efficacy on POA inhibition to a certain extent, thoroughly preventing POA formation is still challenging. Meanwhile, most biomaterials for POA prevention were designed based on limited experiences, not a solid theoretical basis, showing blindness. Hence, we aimed to provide guidance for designing anti-adhesion materials applied in different soft tissues based on the mechanisms of POA occurrence and development. We first classified the postoperative adhesions into four categories according to the different components of diverse adhesion tissues, and named them as "membranous adhesion", "vascular adhesion", "adhesive adhesion" and "scarred adhesion", respectively. Then, the process of the occurrence and development of POA were analyzed, and the main influencing factors in different stages were clarified. Further, we proposed seven strategies for POA prevention by using biomaterials according to these influencing factors. Meanwhile, the relevant practices were summarized according to the corresponding strategies and the future perspectives were analyzed.

Chitosan 3D scaffolds with resolvin D1 for vertebral arthrodesis: a pilot study

PURPOSE

Over the last years, the number of vertebral arthrodesis has been steadily increasing. The use of iliac crest bone autograft remains the "gold standard" for bone graft substitute in these procedures. However, this solution has some side effects, such as the problem of donor site morbidity indicating that there is a real need for adequate alternatives. This pilot study aimed to evaluate the usefulness of chitosan (Ch) porous 3D scaffolds incorporated with resolvin D1 (RvD1) as an alternative implant to iliac bone autograft.

METHODS

We have performed bilateral posterolateral lumbar vertebral arthrodesis in a rat animal model. Three experimental groups were used: (i) non-operated animals; (ii) animals implanted with Ch scaffolds incorporated with RvD1 and (iii) animals implanted with iliac bone autograft.

RESULTS

The collagenous fibrous capsule formed around the Ch scaffolds with RvD1 is less dense when compared with the iliac bone autograft, suggesting an important anti-inflammatory effect of RvD1. Additionally, new bone formation was observed in the Ch scaffolds with RvD1.

CONCLUSION

These results demonstrate the potential of these scaffolds for bone tissue repair applications.

The effectiveness of spatially cross-linked polymer in the postoperative epidural fibrosis prevention: an experimental study

Introduction. Epidural fibrosis is an urgent problem in modern spinal surgery and orthopedics. The formation of connective tissue in the epidural space after performing surgical interventions on the spinal column inevitably leads to adhesion of the latter to the dura mater and compression of neural structures, followed by the formation of clinical and neurological symptoms. The  search for literary sources in domestic and foreign scientific databases has demonstrated the presence of several works studying the effectiveness of barrier methods for preventing the development of epidural fibrosis. It should be noted that the results of these studies are ambiguous and largely contradictory.

The purpose was to study the effectiveness of using a spatially cross-linked polymer in the postoperative lumbar epidural fibrosis prevention in an experiment.

Materials and methods. The study included 26 male Wistar rats (average body weight 338.5±9.07 g), which were divided into two groups: Group I (control, n = 12): animals underwent laminectomy at the level of vertebral bodies LVII – SI  without application of spatially crosslinked polymer; Group II (experimental, n = 14): animals underwent laminectomy at the level of vertebral bodies LVII – SI  followed by application of a spatially cross-linked polymer to the dura mater. The morphological and instrumental parameters were studied.

Results. Significant differences were noted in the severity of epidural fibrosis (χ2 = 14.846, p = 0.003), the number of newly formed vessels (F = 14.371, p<0.001), the number of fibroblasts (F = 11.158, p<0.001), as well as in the severity of vertebral stenosis channe l according to multislice computed tomography (χ2 = 17.207, p=0.002) between the control and experimental groups of animals.

Conclusion. Application of a spatially cross-linked polymer to the dura mater is an effective way to prevent the development of postoperative epidural fibrosis.

Chitosan-Hydroxyapatite Scaffold for Tissue Engineering in Experimental Lumbar Laminectomy and Posterolateral Spinal Fusion in Wistar Rats

Study Design

Experimental study with an animal model.

Purpose

To evaluate the role of a chitosan and hydroxyapatite composite for spinal fusion in a lumbar experimental model based on regenerative tissue engineering principles.

Overview of Literature

Chitosan and hydroxyapatite represent an alternative biodegradable implant material for tissue engineering and regeneration. The combination of chitosan and hydroxyapatite in a 20:80 ratio could potentiate their individual properties as an implantable composite for experimental laminectomy.

Methods

Phase I: design and synthesis of a porous composite scaffold composed of chitosan-hydroxyapatite using a freeze drying technique. Phase II: experimental microsurgical lumbar laminectomy at L5. A total of 35 Wistar rats were categorized into three experimental groups: control (laminectomy alone), experimental (laminectomy with implant), and reference (intact spine) (n=5 per group). Postoperative structural and functional evaluations were performed using computed tomography scans. In addition, radiologic, clinical, histological, and immunohistochemical microstructures were evaluated.

Results

At the laminectomy site, the composite implant induced bone regeneration, which was observed in the axial reconstruction of the rat lumbar spine in all cases. Biomechanical changes in the lumbar spine were observed by radiology in both groups after the surgery. The posterolateral space was covered by a bone structure in the treated spine, a condition not seen in the control group. The range of motion was 7.662°±0.81° in the scaffold group versus 20.72°±3.47° in the control group. Histological findings revealed qualitatively more bone tissue formation in the implant group.

Conclusions

A composite of chitosan-hydroxyapatite at a 20:80 ratio induced bone formation after experimental laminectomy in rats and led to spinal fusion, which was assessed by radiology and biomechanical tests. No functional complications in posture or walking were observed at 90 days post-surgery, despite biomechanical changes in the spine.

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.

Effects of rapamycin on reduction of peridural fibrosis: an experimental study

Background

Peridural fibrosis (PF) is a normal complication after lumbar surgery. It is a challenge for both surgeons and patients. Rapamycin (RPM), a novel antibiotic with anti-proliferative and immunosuppressive properties, has been shown to be effective in preventing uncontrolled scar proliferation diseases. The object of the present research was to investigate the effects of RPM on inhibiting PF in vitro and in vivo.

Material/Methods

In vitro, the fibroblasts collected and isolated from the rat tail skin were cultured with/without RPM and cell counting was performed. In vivo, the double-blinded study was conducted in 60 healthy Wistar rats divided randomly into 3 groups: 1) RPM treatment group; 2) Vehicle treatment group; 3) Control group. Rats underwent a L1-L2 level laminectomy with a satisfactory anesthetization. Four weeks post-operatively, the Rydell score, histological analysis, hydroxyproline content, vimentin expressional level, and inflammatory cytokines expressional levels were assessed.

Results

In vitro, RPM showed ability to prevent fibroblast proliferation. In vivo, the laminectomy was well tolerated by all rats, which were killed 4 weeks post-operatively. The Rydell score, histological evaluation, hydroxyproline content, vimentin expression level, and inflammatory activity showed the positive effect of RPM in preventing peridural adhesion, inhibiting fibrotic formation and collagen synthesis, and down-regulating inflammation.

Conclusions

In the present primary study, RPM showed good efficacy in preventing the proliferation of fibroblasts. RPM can prevent rat peridural adhesion through inhibiting collagen synthesis, fibroblasts proliferation, and inflammatory activity.