A modern biomaterial for adhesion prevention

Prevention of Adhesions after Bone Fracture Using a Carboxymethylcellulose and Polyethylene Oxide Composite Gel in Dogs

The formation of adhesions is a common complication following traumatic injuries and surgical procedures, often resulting in pain, stiffness, and loss of function. This study aimed to evaluate the feasibility and safety of using a composite material comprising of carboxymethylcellulose (CMC), polyethylene oxide (PEO), and calcium chloride, for preventing adhesions between muscle and bone during the healing stage, as well as its effect on the bone healing process. Ten healthy purpose-bred laboratory Beagle dogs were randomly subjected to two consecutive operations with a 6-month interval, alternating between left and right forelimbs. On the left forelimb an osteotomy at the ulna was performed, while on the right forelimb the same procedure was supplemented by the application of the anti-adhesion agent in the osteotomy site prior to closure. Clinical, diagnostic imaging, macroscopic, and histological evaluations were performed at various time points. The results showed no significant differences in surgical site perimeter (p = 0.558), lameness (p = 0.227), and radiographic bone healing (p = 0.379) between the two groups. However, the macroscopic (p = 0.006) and histological assessments revealed significantly lower adhesion scores (p = 0.0049) and better healing (p = 0.0102) in the group that received the anti-adhesion agent. These findings suggest that the CMC/PEO composite material is a safe and potentially effective intervention for preventing post-traumatic and post-surgical adhesions in canine patients without compromising bone healing. Further research is warranted to fully characterize the clinical benefits of this approach.

Comparison of the preventive effect of colchicine versus diphenhydramine, prednisolone, and a combination therapy on intraperitoneal adhesion bands: an experimental study in rats

BACKGROUND

Peritoneal adhesion formation is an inevitable consequence of abnormal repair of the peritoneum following different peritoneal injuries of intra-abdominal operations with the subsequent morbidity that they represent. Vast efforts have been made to elucidate the cause and prevent the development of abdominal adhesions. The aim of our study is to compare the capability of colchicine versus diphenhydramine (DPH) and methylprednisolone (MP), and also prednisolone in adhesion prevention.

METHODS

Sixty-one male Wistar stock rats were divided into four groups. The first group attended as the control group. Groups 2, 3, and 4 received oral combination of MP + DPH solution (20 mg/kg), colchicine (0.02 mg/kg), and prednisolone (1 mg/ kg), respectively. Adhesion bands were induced by standardized abrasion of the peritoneum through a midline laparotomy. All rats were sacrificed on the 15^th-day post medication administration and the subjects underwent an exploratory laparotomy. The presence of adhesions was evaluated with the modified using Nair's classification.

RESULTS

The proportion of the control group with substantial adhesion bands (73.3%) was significantly higher than that of the MP + DPH (13.3%), colchicine (33.3%), and prednisolone (31.3%) groups. There were significant differences between the scores of the control and the MP + DPH, colchicine, and prednisolone groups (P = 0.001, 0.028, and 0.019, respectively). There was no statistically significant difference to favor colchicine against MP + DPH (P = 0.390) or MP + DPH against prednisolone (P = 0.394).

CONCLUSIONS

Both colchicine and combination of DPH + MP prevented postoperative abdominal adhesions separately in our study. However, the lowest adhesion formation rate was observed in the DPH + MP group, even lower than the prednisolone group.

Acoustofluidic separation of proteins from platelets in human blood plasma using aptamer-functionalized microparticles

Microfluidic liquid biopsy has emerged as a promising clinical assay for early diagnosis. Herein, we propose acoustofluidic separation of biomarker proteins from platelets in plasma using aptamer-functionalized microparticles. As model proteins, C-reactive protein and thrombin were spiked in human platelet-rich plasma. The target proteins were selectively conjugated with their corresponding aptamer-functionalized microparticles of different sizes, and the particle complexes served as a mobile carrier for the conjugated proteins. The proposed acoustofluidic device was composed of an interdigital transducer (IDT) patterned on a piezoelectric substrate and a disposable polydimethylsiloxane (PDMS) microfluidic chip. The PDMS chip was placed in a tilted arrangement with the IDT to utilize both vertical and horizontal components of surface acoustic wave-induced acoustic radiation force (ARF) for multiplexed assay at high-throughput. The two different-sized particles experienced the ARF at different magnitudes and were separated from platelets in plasma. The IDT on the piezoelectric substrate could be reusable, while the microfluidic chip can be replaceable for repeated assays. The sample processing throughput with the separation efficiency >95% has been improved such that the volumetric flow rate and flow velocity were 1.6 ml/h and 37 mm/s, respectively. For the prevention of platelet activation and protein adsorption to the microchannel, polyethylene oxide solution was introduced as sheath flows and coating on to the walls. We conducted scanning electron microscopy, x-ray photoemission spectroscopy , and sodium dodecyl sulfate- analysis before and after the separation to confirm the protein capture and separation. We expect that the proposed approach will provide new prospects for particle-based liquid biopsy using blood.

Effects of glycerol and sodium pentaborate containing new formulation on sleeve gastrectomy model in rats

Purpose:

The development of cutting surface leakage and postoperative peritoneal adhesions (PPA) after sleeve gastrectomy (SG) are the most serious operative complications. We investigated the effectiveness of the newly developed glycerol and sodium pentaborate containing formulation on the prevention of these complications.

Methods:

Sixteen Sprague Dawley rats (mean weight 310 ± 50 g, mean age 3 months old) were divided into two groups, consisting of eight rats in each. SG and a double-layer suture technique were performed for each group. In study group, there was the mixture of 2 mL 3% glycerol plus 3% sodium pentaborate formulation, and in the control group 2 mL 0.9% NaCl was injected into the peritoneal cavity. Rats were sacrificed after 30 days, then macroscopic adhesion grade scoring and histopathological evaluations were assessed.

Results:

Macroscopic PPA scores in the control and study groups were 2.75 ± 0.16 and 1.50 ± 0.327, respectively (p = 0.004). Histopatologic fibrosis scores in the control and study groups were 0.87 ± 0.125 and 2.00 ± 0.26, respectively (p = 0.002).

Conclusions:

In SG operation model, glycerol plus sodium pentaborate compound decreased PPA formation and also increased stomach cut surface line fibrosis. This new formulation is hopeful for more safe SG operations.

Improving flexor tendon gliding by using the combination of carboxymethylcellulose‑polyethylene oxide on murine model

The current approach to flexor tendon injuries is complex and is no longer limited to suturing techniques. Strategies for improving hand function currently include rehabilitation protocols, appropriate suturing materials and techniques, changing the gliding surface by using lubricants and providing growth factors. One product, originally used in spinal surgery, has been shown to be effective in preventing postoperative adhesions. It is a combination of carboxymethylcellulose and polyethylene oxide-Dynavisc^® (FzioMed, Inc.). The aim of the present study was to test the effect of Dynavisc^® on acute injuries of the intrasynovial flexor tendons in the prevention of postoperative adhesions and the improvement of functional results. The study was performed on 20 Wistar rats distributed in two groups. The control group, represented by 10 rats, in which after the reconstruction of the flexor tendon, the peritendinous area was injected with saline solution and the study group, in which the peritendinous area was injected with a single administration of the lubricating gel, Dynavisc^® (carboxymethylcellulose and polyethylene oxide). At 4 and 12 weeks, the rats were sacrificed and tissue biopsy consisted of tendon fragments and adjacent tissue. The evaluation of the results was performed by measuring the adhesion score and observing histological parameters. The presence of important adhesions was found in the control group compared with the group treated with Dynavisc^®, where a supple and smooth tendon, with significantly fewer adhesions were found. The differences between the two groups were significant, thus indicating the efficiency of the lubricant in preventing adhesions. This study supported the important role of Dynavisc^® in the regeneration of the tendon and the peritendinous structures, by limiting aberrant fibrous proliferation in the regeneration process and helping to build a peritendinous space.

Anti-Adhesive Effect of Porous Polylactide Film in Rats

Excessive adhesion between tissues on a significant area can cause the development of disorders, cosmetic problems, and ileus. Methods for preventing adhesion include the use of drugs and anti-adhesion barriers for physical blocking. In this study, the adhesion prevention effect of polylactide film in porous form was analyzed. A porous polylactide film was manufactured using a molecular weight of at least 100,000. To generate porosity, 98% methylene chloride and 95% ethyl alcohol were used as solvents. The thickness, surface, and internal pore shape of film were investigated. The crystal structures and melting temperature of film were measured. In the rat model, the presence and severity of adhesion were then analyzed. The thickness of the film ranged from 10 to 20 µm. The surface of the film contained pores with diameters of less than 10 µm. Partial crystallinity appeared from 15° to 20°, but the structure was amorphous overall. In the rat cecum abrasion model, adhesion occurred in 3 of the 13 rats in the polylactide experimental group, representing a 23.1% incidence rate. There were statistically significant differences in the severity of adhesion. The use of porous polylactide films can reduce the incidence of adhesion.

Effects of Glycerol and Sodium Pentaborate Formulation on Prevention of Postoperative Peritoneal Adhesion Formation

Background

Postoperative peritoneal adhesions (PPA) are a serious problem for abdominal surgery. An effective remedy has not been found yet. New formulation of glycerol and sodium pentaborate may be able to solve the problem.

Method

Female Wistar albino rats were randomly assigned into four equal groups. The adhesion model was created on the caecum anterior wall and covered with 2 ml 0.9% NaCl, 3% glycerol, 3% sodium pentaborate, and 3% glycerol plus 3% sodium pentaborate solutions in the groups, respectively. Two weeks later, the rats were sacrificed. PPA were graded macroscopically and microscopically.

Results

Total adhesion scores of the 3% glycerol + 3% sodium pentaborate group were statistically different from the other groups for macroscopic and also microscopic evaluations (p < 0.001).

Conclusion

3% glycerol plus 3% sodium pentaborate as a new formulation has preventive effects on PPA with a synergistic mechanism.

Extrudable salicylic acid-based poly(anhydride-esters) for injectable drug releasing applications

Injectable biomaterials have attracted more and more interest owing to their advantages over traditional open surgeries: minimal invasive procedure and ease of handling. Commonly used synthetic injectable polymers exhibited low drug loading and poor biodegradability. In this work, we describe a novel series of degradable copolymers comprising salicylic acid–based poly(anhydride-esters) and poly(ethylene glycol) subunits suitable for injectable drug releasing applications. By tuning the rheology properties, these salicylic acid–based poly(anhydride-esters) and poly(ethylene glycol) copolymers may function as injectable drug delivery vehicles that deliver salicylic acid at the injury site. These copolymers were designed to have glass transition temperatures (Tg) below 0ºC, resulting in extrudable polymers that behave like viscous fluids at room temperature. Salicylic acid–based poly(anhydride-esters) and poly(ethylene glycol) copolymers of different ratios (2:1, 1:1, and 1:2 salicylic acid–based poly(anhydride-esters) and poly(ethylene glycol)) were synthesized and characterized by nuclear magnetic resonance and Fourier-transform infrared spectroscopies. Their shear viscosities were determined both at room and physiological temperatures. The in vitro drug release profiles, cytotoxicity, and anti-inflammatory activities were assessed. The shear viscosities were found to compare favorably with current injectable barrier materials on the market.

Inflammation by activated macrophage-like THP-1 cells increases human dura mater cell adhesion with alteration of integrin α2 β1 and matrix metalloproteinase

This study was designed to investigate (i) extracellular matrix to specify adhesive substrates to human dura mater cell (hDMC); (ii) the alteration on adhesion-related molecules in hDMC; and (iii) secreted matrix metalloproteinases (MMPs) linked with extracellular matrix remodeling after exposure to inflammation. The hDMC was cultured from human dura mater tissue, and the studies were performed with hDMC after co-culturing with macrophage like THP-1 cells (Mϕ). The adhesion of co-cultured hDMC through collagen I increased 6.4-fold and through collagen IV increased 5.0-fold compared with the adhesion of naïve cells (p < 0.001). Integrin subtype α₂ β₁ expression was increased 6.3-fold (p < 0.001) and α₁ expression was decreased 2.0-fold (p < 0.001) in the co-cultured cells compared with the naïve cells. Co-culturing induced significant increases in MMP-1 (13.9-fold, p < 0.01), MMP-3 (7.6-fold, p < 0.01), and VEGF (VEGF: 3.8-fold, p < 0.05) expression and decreases in MMP-9 (0.1-fold, p < 0.01) compared with the sum of naïve hDMC and Mϕ values. Increased hDMC adhesion under inflammatory conditions is caused by an increased cellular affinity for collagen I and IV mediated by increased hDMC levels of integrin subtype α₂ β₁ and environmental MMP-1, -3 and decreased MMP-9. Selective integrin subtype α₂ β₁ inhibition assay showed 37.8% and 35.7% reduction in adhesion of co-cultured hDMC to collagen I (p < 0.001) and IV (p = 0.057), respectively. The present study provides insight into the pathological conditions related to dura mater adhesion in inflammation. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-11, 2019.

A fibrin-coated pericardial extracellular matrix prevented heart adhesion in a rat model

As most surgical treatments pose a risk of tissue adhesion, methods to prevent adhesion are needed across various surgical fields. In this study, we investigated the use of a decellularized pericardium with fibrin glue to prevent rat heart adhesion. Porcine pericardia were decellularized by a high-hydrostatic pressure method. Cells adhered to the resulting pericardial extracellular matrix (ECM) during an in vitro cell-seeding test, but fibrin-coated pericardial ECM showed reduced cell adhesion. In a rat surgical model of heart adhesion, the fibrin-coated pericardial ECM did not adhere to the heart and mesothelial cell adhesion was observed on the ECM surface. Notably, the anti-adhesion effect of fibrin-coated pericardial ECM was observed 4 weeks after surgery. These results support the utility of fibrin-coated pericardial ECM as an adhesion prevention material for cardiovascular surgery. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1088-1094, 2019.

Effectiveness of the Biophysical Barriers to the Peridural Fibrosis in Rat Laminectomy Model

Purpose: Peridural fibrosis which could occur after the spinal surgery could adhere neural tissue closely and may cause to neural entrapment symptoms and require surgical reintervention. Aim of the study: Present study was designed to reduce occurrence of peridural fibrosis in rat laminectomy model by using biophysical barriers called hyaluronic acid (HAS) dural barrier, activated polyethylene glycol and polyethylene imine (PEG) dural barrier, and platelet-rich plasma (PRP). Materials and methods: In this study, 2 of 26 male Wistar albino rats (325-350 g body weight), which were not included into study groups were sacrificed by removing their total blood and their blood was used for preparation of PRP, and remaining rats were randomly delivered into four groups called SHAM, HAS, PEG, and PRP groups. Then L3-4-5 laminectomy was performed to all animals and experimental agents were administered to the selected groups mentioned above. Spinal colons of all animals were removed gross total after 6-week period and investigated histopathologically. Additionally, real-time-polymerase chain reaction was used to obtain collagen type I and type III, transforming growth factor-1β, and tumor necrosis factor-α gene expressions. Results: All results demonstrated that polyethylene glycol and polyethylene imine dural barrier and PRP could decrease peridural fibrosis formation efficiently in rat. Conclusion: Present study results suggested that to reduce or block formation of peridural fibrosis, either polyethylene glycol and polyethylene imine dural barrier or PRP could be used effectively in human subjects after they will be closely investigated in future studies.

Magnetic Resonance Imaging Signal Characteristics of Medishield: Early Postoperative Profile in a Rabbit Interlaminotomy Model

OBJECTIVE

Application of Medishield to the nerve root is common during spinal surgery to create a mechanical barrier from pain mediators and reduce scar formation. However, Medishield's signal characteristics on magnetic resonance imaging (MRI) have not yet been examined.

METHODS

Microsurgical interlaminotomy was performed on 2 lower lumbar segments in 17 adult New Zealand white rabbits. After dural exposure, applications of 1 mL (autologous blood clot or Medishield) were randomized for each level. On postoperative days 1 through 3, various MRI sequences in 1.5T were performed including T1-weighted, T2-w, T1-gadolinium-weighted, susceptibility-weighted and turbo inversion recovery magnitude (TIRM) sequence. Signaling characteristics were analyzed by 3 blinded observers. Inter-rater agreement was calculated using Fleiss's kappa coefficient (κ). Positive and negative likelihood ratios in detecting Medishield by MRI were determined.

RESULTS

Of 24 MRIs performed, TIRM sequence identified Medishield with the highest likelihood ratio. Medishield's positive likelihood ratio was highest (5.8) on postoperative day 1 with interobserver agreement of 93% (κ = 0.75); these rates declined to 2.5 and 1.4 on postoperative days 2 and 3 with interobserver agreements of 71% (κ = 0.43) and 83% (κ = 0.67), respectively. Medishield adherence was confirmed in each rabbit by histologic examinations.

CONCLUSION

Understanding that radiologic detection of Medishield diminished over time as its signal characteristics became less distinguishable from a blood clot is essential in clinical practice. Medishield was detected on postoperative day 1 but not 2 days later after hemodynamic changes had occurred. These results may provide a guide for postoperative findings, such as differential diagnosis of hematoma.

Effects of Systemic and Local Interferon Beta-1a on Epidural Fibrosis

Study Design

Level 1 randomized controlled study.

Purpose

To investigate the effects of systemic and local interferon-beta-1a (IFN-β-1a) on prevention of epidural fibrosis using histopathological parameters.

Overview of Literature

Epidural fibrosis involves fibroblastic invasion of nerve roots into the epidural space. Formation of dense fibrous tissue causes lumbar and radicular pain. Many surgical techniques and several materials have been proposed in the literature, but no study has assessed the effect of IFN-β-1a on prevention of epidural fibrosis.

Methods

Forty-eight adult female Sprague-Dawley rats were divided into six groups of eight: sham group, control group, systemic 44 μg IFN-β-1a group and 22 μg IFN-β-1a group (after laminectomy and discectomy, 0.28 mL and 0.14 mL IFN-β-1a applied subcutaneously three times for a week, respectively), local 44 μg IFN-β-1a group (laminectomy and discectomy, followed by 0.28 mL IFN-β-1a on the surgical area), and local 22 μg IFN-β-1a group (laminectomy and discectomy, followed by 0.14 mL IFN-β-1a on the surgical area). All rats were sacrificed after 4 weeks and groups were evaluated histopathologically.

Results

Compared with sham and control groups, significantly less epidural fibrosis, dural adhesion, and fibroblast cell density were observed in the local and systemic 44 μg IFN-β-1a groups. No other differences were evident between the local and systemic groups.

Conclusions

IFN-β-1a is effective in preventing epidural fibrosis with systemic and local application.

Efficacy of anti-adhesion gel of carboxymethylcellulose with polyethylene oxide on peripheral nerve: Experimental results on a mouse model

INTRODUCTION

Perineural scar formation is responsible for pain and loss of function after surgical procedures. Neurolysis and application of anti-adhesion gels are required to restore a gliding surface. We tested a carboxymethylcellulose (CMC) and polyethylene oxide (PEO) gel on mouse sciatic nerve to describe its safety and efficacy.

METHODS

Adult mice underwent a surgical procedure in which we burned the muscular bed of the sciatic nerve bilaterally (Burned group) and applied anti-adhesion gel to 1 of the nerves (Burned+gel group). After 3 weeks, we studied scar tissue by biomechanical and histological evaluation.

RESULTS

Both histological and biomechanical analysis showed that the gel reduced perineural scarring. The difference between the Burned and Burned+gel groups was statistically significant.

CONCLUSIONS

CMC-PEO gel can reduce perineural scar tissue. In histological section, scar tissue was present in both groups, but in the Burned+gel group a gliding surface was identified between scar and nerve.

Dexamethasone and sodium carboxymethyl cellulose prevent postoperative intraperitoneal adhesions in rats

We aimed to evaluate the effects of the barrier agent sodium carboxymethyl cellulose (SCMC) with and without dexamethasone for the prevention of postoperative adhesion formation in a rat model of postoperative peritoneal adhesion. A total of 160 three-month old male and female Wistar rats underwent a laparotomy, and adhesions were induced by ileocecal abrasion. Rats were randomly assigned to 4 groups (n=40 each): group A, untreated; group B, treated with SCMC only; group C1, treated with SCMC + 3 mg dexamethasone, and group C2, treated with SCMC + 8 mg dexamethasone. After 12 days, adhesion formation and histopathological changes were compared. In groups A, B, C1, and C2, the mortality rates were 10, 5, 5, and 5%, respectively. In groups C1 and C2, the adhesions were filmy and easy to dissect and were milder compared with those in groups A and B. The total adhesion score in group C1 (3.38±0.49) was significantly lower than that of group B (6.01±0.57; P<0.01) or group A (8.01±0.67; P<0.05). There was no significant difference in adhesion formation between groups C1 and C2. Compared with groups A and B, groups C1 and C2 exhibited milder histopathological changes. SCMC in combination with dexamethasone can prevent adhesion formation and is a better barrier agent than SCMC alone. The safety and feasibility of SCMC in combination with dexamethasone to prevent adhesion formation after abdominal surgery warrants further clinical study.

Antiadhesive Property of Photoreactive Azidophenyl Low-Molecular-Weight Chitosan in Rabbit Laminotomy Model

Newly developed photoreactive azidophenyl chitosan (P-ALMC) has characteristics of a transformable gel type and its outer layer could be sealed up like a film after UV radiation. We aim to evaluate the antiadhesive properties of P-ALMC through comparing it with hyaluronic acid-carboxymethylcellulose membrane (HA-CMC) in a rabbit laminotomy model. Laminotomies were performed at the L3-4, L4-5, and L5-6 levels in 41 rabbits and each level was randomly assigned to either receive saline (group I), HA-CMC (group II), or P-ALMC (group III). The extent of peridural fibrosis, density of fibroblasts and inflammatory cells, and dural thickness were evaluated at 6 and 12 weeks postoperatively. In the groups II and III, the extents of peridural fibrosis and dural thickness were significantly smaller than those in group I (P<0.001) and no differences between groups II and III were found at the postoperative 6 and 12 weeks. There were no differences of cell density among groups. P-ALMC showed effective antiadhesive properties comparable to HA-CMC and could be one of the candidates as an anti-adhesive agent for spine surgery even further study is required to identify the effectiveness of its unique characteristics as mechanical barrier.

Mesothelial morphology and organisation after peritoneal treatment with solid and liquid adhesion barriers--a scanning electron microscopical study

Separation of traumatized tissue represents the only promising strategy in postoperative adhesion prevention, a relevant clinical problem after surgical intervention. In the present study scanning electron microscopy (SEM) and subsequent morphometry were used to analyse the tissue response to five commercial adhesion barriers. Standardised peritoneal lesions in Wistar rats were covered with solid and viscous barrier materials and semiquantitatively analysed 14 days postoperatively. Striking morphological differences in lesion surface organisation between the barrier groups became apparent with colonisation of the barrier by mesothelial cells to different degrees. Furthermore, the mesothelial cells showed either a normal or activated phenotype depending on the underlying biomaterial. These experiments demonstrate that the examination by SEM gives useful insights into the performance of barrier materials and the cellular processes of adhesion prevention, since mesothelial cells play an active role in the pathogenesis of adhesion formation.

Current strategies and future perspectives for intraperitoneal adhesion prevention

INTRODUCTION

The formation of peritoneal adhesions still is a relevant clinical problem after abdominal surgery. Until today, the most important clinical strategies for adhesion prevention are accurate surgical technique and the physical separation of traumatized serosal areas. Despite a variety of barriers which are available in clinical use, the optimal material has not yet been found.

DISCUSSION

Mesothelial cells play a crucial physiological role in friction less gliding of the serosa and the maintenance of anantiadhesive surface. The formation of postoperative adhesions results from a cascade of events and is regulated by various cellular and humoral factors. Therefore, optimization or functionalization of barrier materials by developments interacting with this cascade on a structural or pharmacological level could give an innovative input for future strategies in peritoneal adhesion prevention. For this purpose, the proper understanding of the formal pathogenesis of adhesion formation is essential. Based on the physiology of the serosa and the pathophysiology of adhesion formation, the available barriers in current clinical practice as well as new innovations are discussed in the present review.

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.

Intraperitoneal adhesions--an ongoing challenge between biomedical engineering and the life sciences

Peritoneal adhesions remain a relevant clinical problem despite the currently available prophylactic barrier materials. So far, the physical separation of traumatized serosa areas using barriers represents the most important clinical strategy for adhesion prevention. However, the optimal material has not yet been found. Further optimization or pharmacological functionalization of these barriers could give an innovative input for peritoneal adhesion prevention. Therefore, a more complete understanding of pathogenesis is required. On the basis of the pathophysiology of adhesion formation the main barriers currently in clinical practice as well as new innovations are discussed in the present review. Physiologically, mesothelial cells play a decisive role in providing a frictionless gliding surface on the serosa. Adhesion formation results from a cascade of events and is regulated by a variety of cellular and humoral factors. The main clinically applied strategy for adhesion prevention is based on the use of liquid or solid adhesion barriers to separate physically any denuded tissue. Both animal and human trials have not yet been able to identify the optimal barrier to prevent adhesion formation in a sustainable way. Therefore, further developments are required for effective prevention of postoperative adhesion formation. To reach this goal the combination of structural modification and pharmacological functionalization of barrier materials should be addressed. Achieving this aim requires the interaction between basic research, materials science and clinical expertise.

Development of complete thoracic spinal cord transection model in rats for delayed transplantation of stem cells

STUDY DESIGN

In vivo study of a rat spinal cord injury model.

OBJECTIVES

To develop complete transection model of thoracic spinal cord using a polymer sheet and a microtube relevant for delayed transplantation of stem cells.

SUMMARY OF BACKGROUND DATA

Stem cell transplantation for the regeneration of spinal cord injuries has used animal models. However, current models suffer from inflammation and leakage, which lessens their usefulness in studying delayed stem cell transplantation.

METHODS

Thoracic spinal cord at T9 level of adult Sprague-Dawley rats was exposed and a 50:50 sheet of poly(D,L-lactic-coglycolic acid) was inserted, exposed spinal cord was completely transected, and collagen was filled between the gap between the proximal and distal stumps of transected spinal cord. A microtube was placed and fixed between the polymer surfaces facing each other. Behavior testing, magnetic resonance imaging, and myelography were performed to characterize the new complete transection with a gap formation and polymer insertion (GAP) model and to compare the GAP model with the control models. Human mesenchymal stem cells (hMSCs) were transplanted into 3 models and immunohistochemistry and western blot were performed.

RESULTS

The inserted poly(D,L-lactic-coglycolic acid) sheet was completely disappeared 10 weeks after operation, but the inserted microtube remained firmly fixed in its original position. Myelography of the GAP model showed no leakage of contrast medium around the injured spinal cord, whereas magnetic resonance imaging of the severe contusion and simple transection models showed some leakage of contrast medium. Immunohistochemistry and western blot after hMSCs transplantation indicated that transplanted hMSCs survived and migrated well in the GAP model, and the deposition of inflammatory cells in GAP model was less than a simple transection model or severe contusion model.

CONCLUSION

The developed GAP model is more relevant for delayed transplantation of stem cells for the study of regeneration of spinal cord injury of rats.

Efficacy of glycerol in preventing postoperative peritoneal adhesions

AIM

To evaluate the efficacy of glycerol in preventing postoperative peritoneal adhesions.

MATERIALS AND METHODS

Forty Wistar albino female rats were randomly assigned into four groups of 10 rats each. Rats in group 1 were each injected intraperitoneally with 0.1 mL glycerol. In group 2, the adhesion model was created with no injection of glycerol. In group 3, the adhesion model was created and the area was covered with 0.1 mL glycerol. In group 4, 0.1 mL glycerol was used to cover the area where the model was to be formed and the adhesion model was created. The rats were killed on postoperative day 10, and the size and severity of adhesions were evaluated, together with histopathological fibrosis parameters.

RESULTS

Mean macroscopic adhesion scores in groups 1-4 were, 0, 5.8 +/- 0.42, 0.30 +/- 0.95 and 0, respectively (P = 0.0001), with the score in group 2 higher than those of groups 1 (P < 0.001), 3 (P < 0.01) and 4 (P < 0.001). Mean histopathological fibrosis values were 0, 2.8 +/- 0.32, 1.60 +/- 0.70 and 0.60 +/- 0.51, respectively (P < 0.0001). Group 3 and 4 scores were different than group 2 (P < 0.0001) and group 3 was also different than group 4 (P < 0.001).

CONCLUSION

Covering peritoneal surfaces with glycerol, both before and after peritoneal trauma, is effective in decreasing peritoneal adhesion formation. The efficacy of glycerol covering was greater in the group receiving glycerol prior to trauma because it decreased the direct effects of trauma on the surface.

Use of Temporary Implantable Biomaterials to Reduce Leg Pain and Back Pain in Patients with Sciatica and Lumbar Disc Herniation

The principle etiology of leg pain (sciatica) from lumbar disc herniation is mechanical compression of the nerve root. Sciatica is reduced by decompression of the herniated disc, i.e., removing mechanical compression of the nerve root. Decompression surgery typically reduces sciatica more than lumbar back pain (LBP). Decompression surgery reduces mechanical compression of the nerve root. However, decompression surgery does not directly reduce sensitization of the sensory nerves in the epidural space and disc. In addition, sensory nerves in the annulus fibrosus and epidural space are not protected from topical interaction with pain mediators induced by decompression surgery. The secondary etiology of sciatica from lumbar disc herniation is sensitization of the nerve root. Sensitization of the nerve root results from a) mechanical compression, b) exposure to cellular pain mediators, and/or c) exposure to biochemical pain mediators. Although decompression surgery reduces nerve root compression, sensory nerve sensitization often persists. These observations are consistent with continued exposure of tissue in the epidural space, including the nerve root, to increased cellular and biochemical pain mediators following surgery. A potential contributor to lumbar back pain (LBP) is stimulation of sensory nerves in the annulus fibrosus by a) cellular pain mediators and/or b) biochemical pain mediators that accompany annular tears or disruption. Sensory fibers located in the outer one-third of the annulus fibrosus increase in number and depth as a result of disc herniation. The nucleus pulposus is comprised of material that can produce an autoimmune stimulation of the sensory nerves located in the annulus and epidural space leading to LBP. The sensory nerves of the annulus fibrosus and epidural space may be sensitized by topical exposure to cellular and biochemical pain mediators induced by lumbar surgery. Annulotomy or annular rupture allows the nucleus pulposus topical access to sensory nerve fibers, thereby leading to LBP. Coverage of the annulus and adjacent structures in the epidural space by absorbable viscoelastic gels appears to reduce LBP following surgery by protecting sensory fibers from cellular and biochemical pain mediators.

A new approach for decreasing postoperative peritoneal adhesions: preventing peritoneal trauma with soybean oil

BACKGROUND

Covering peritoneal surfaces with soybean oil may decrease peritoneal adhesions by preventing peritoneal trauma.

METHOD(S)

Forty female albino Wistar rats were divided into four equal groups. In Group 1, soybean oil only (0.1 ml) was injected into the peritoneal cavity. In Group 2, an untreated adhesion model was generated. In Group 3, an adhesion model was generated, followed by covering the area with soybean oil (0.1 ml). In Group 4, the area was first covered with soybean oil (0.1 ml) followed by generation of an adhesion model. All rats were sacrificed on postoperative day 10, and adhesions were scored.

RESULTS

The mean macroscopic adhesion scores in Groups 1, 2, 3, and 4 were 0.0 +/- 0.0, 2.90 +/- 0.21, 1.90 +/- 0.94, and 0.50 +/- 0.71, respectively. The Group 4 score differed significantly from that of Group 2 (p <. 001), but was not different from that of Group 1 or 3 (p >. 05).

DISCUSSION

Soybean oil can effectively decrease adhesion formation if applied before peritoneal trauma.

Intercoat gel (oxiplex): efficacy, safety, and tissue response in a laparoscopic mouse model

STUDY OBJECTIVE

To study the efficacy and safety of Intercoat gel in a laparoscopic mouse model with pneumoperitoneum-enhanced adhesion formation.

DESIGN

Randomized controlled trial. Evidence obtained from a properly designed, randomized, controlled trial (Canadian Task Force classification I).

SETTING

University laboratory research center.

SUBJECTS

Balb\c female mice 9 to 10 weeks old.

INTERVENTIONS

Two laparoscopic mouse models for adhesion formation were used. In the first model, adhesions following bipolar opposing lesions in the pelvis were enhanced by 60 minutes of carbon-dioxide pneumoperitoneum. In the second model, adhesions were further enhanced by bowel manipulation. The first experiment evaluated the efficacy of Intercoat in both models. The second experiment evaluated the efficacy of Intercoat in the first model, when applied immediately on the lesion, when applied at the end of the pneumoperitoneum, and when applied in the upper abdomen. Biopsy specimens were taken after 7 days and were evaluated after hematoxylin-eosin and CD45 staining.

MEASUREMENTS AND MAIN RESULTS

Qualitative and quantitative adhesion scoring. Morphology was evaluated by standard light microscopy. In both models, Intercoat decreased adhesion formation whether applied immediately on the lesion or at the end of the pneumoperitoneum (qualitative and quantitative scoring p <.0001 and p <.0001, respectively). Intercoat application is associated with tissue redness, vascular congestion, and cellular edema but without an inflammatory reaction. Applied in the upper abdomen, Intercoat does not increase adhesions, but decreases adhesions at higher doses (p =.0024). Intercoat in high doses had a toxic effect (p =.0058).

CONCLUSION

Intercoat is an effective antiadhesion product. It is associated with tissue edema and vasodilatation as observed after 7 days both macroscopically and by histology.