Effect of Temperature-Sensitive Poloxamer Solution/Gel Material on Pericardial Adhesion Prevention: Supine Rabbit Model Study Mimicking Cardiac Surgery

Impact of cyclophosphamide on the morphological and histological changes in polyglycolic acid spacers

In radiotherapy for pediatric abdominal tumors, determining the effect of concurrent chemotherapy on polyglycolic acid (PGA) spacers is crucial; yet this effect has not been validated. Therefore, we aimed to evaluate the impact of cyclophosphamide (CPA) chemotherapy on the PGA spacer using a rat model. Twenty-four rats were implanted with the spacer, and morphological changes in the spacer were assessed on CT for both the CPA-dosed group (40 mg/kg) and the control group. The size and volume of the spacer were quantified using CT, while the degree of adhesion and microscopic examination of the tissue were determined using pathology specimens. Morphologically, the size of the spacer decreased over time in both the CPA-dosed and control groups, with no significant differences observed between groups. No significant differences in adhesion were observed between the two groups. Macrophages were observed around the PGA fibers, suggesting their involvement in the degradation of the PGA spacer. These results suggest that CPA does not cause significant clinically problematic degradation or adverse tissue reactions to the PGA spacer. This study reinforced the benefits of PGA spacers; however, future research focusing on in vivo longitudinal monitoring of individual rats, as well as on humans, is required.

A review of animal models for post-operative pericardial adhesions

Post-operative pericardial adhesions remain a serious complication after cardiac surgery that can lead to increased morbidity and mortality. Fibrous adhesions can destroy tissue planes leading to injury of surrounding vasculature, lengthening of operation time, and increased healthcare costs. While animal models are necessary for studying the formation and prevention of post-operative pericardial adhesions, a standardized animal model for inducing post-operative pericardial adhesions has not yet been established. In order to address this barrier to progress, an analysis of the literature on animal models for post-operative pericardial adhesions was performed. The animal model, method used to induce adhesions, and the time to allow development of adhesions were analyzed. Our analysis found that introduction of autologous blood into the pericardial cavity in addition to physical abrasion of the epicardium caused more severe adhesion formation in comparison to abrasion alone or abrasion with desiccation (vs. abrasion alone p = 0.0002; vs. abrasion and desiccation p = 0.0184). The most common time frame allowed for adhesion formation was 2 weeks, with the shortest time being 10 days and the longest being 12 months. Finally, we found that the difference in adhesion severity in all animal species was similar, suggesting the major determinants for the choice of model are animal size, animal cost, and the availability of research tools in the particular model. This survey of the literature provides a rational guide for researchers to select the appropriate adhesion induction modality, animal model, and time allowed for the development of adhesions.

Comparison of the effect of two anti-adhesion materials on the formation of postoperative adhesions after myomectomy – an experimental study on rabbit does

This study compares the effect of Hyalobarrier Gel and 4DryField® PH on the formation of postoperative adhesions after myomectomy in an experimental study on rabbit does. Thirty experimental animals were divided into three groups: group A – control, group B – use of 4DryField® PH, and group C – use of the Hyalobarrier Gel. A simulated myomectomy was performed in each group. The animals were euthanised 14 days after the procedure and the antiadhesive effect of the above-mentioned preparations was evaluated according to the criteria. Statistical evaluation clearly showed differences in the antiadhesive effect in the scoring systems for groups B and C compared to control group A at a high level of significance. We demonstrated an obvious, statistically confirmed antiadhesive effect of the Hyalobarrier Gel and 4DryField® PH in an experimental model of the rabbit uterus. Comparing both preparations, the Hyalobarrier Gel shows a higher level of effectiveness. Based on the results of the experiment, both preparations can be unambiguously recommended for routine practice.

Prevention of Intra-Abdominal Adhesions Using the Combination of Mediclore® and a Statin

PURPOSE

This study investigated the antiadhesive effects of Mediclore®, rosuvastatin, and a combination of Mediclore and rosuvastatin in a rat adhesion model.

METHODS

The adhesion models (a total of 58 adult male rats) were divided into 4 groups. The control group (group C) received no special materials except for a saline. The experimental groups were treated with 5 mL of Mediclore (group M), rosuvastatin (group R), or rosuvastatin and Mediclore (group RM), and these materials were intraperitoneally placed under the incision. At postoperative day 14, the rats underwent re-laparotomy and adhesiolysis. Three investigators blinded to group assignment scored the extent of adhesion formation, the numbers of remote adhesions, and the extent of acute/chronic inflammation, fibrosis, edema, and congestion on resected specimens via histologic examination.

RESULTS

The macroscopic adhesion score in group RM (7.27 ± 3.51) was significantly lower than those in groups C (13.36 ± 2.24) and R (11.71 ± 1.98); group M (9.13 ± 4.09) had a significantly lower adhesion score than group C. The number of remote adhesions was significantly lower in groups R and RM than in group C. The acute inflammation score, chronic inflammation score, and fibrosis score in group RM; the acute inflammation score in group R; and the fibrosis score in group M were significantly lower than those in group C.

CONCLUSION

The intraperitoneal application of Mediclore and a combination of Mediclore and rosuvastatin effectively reduced postoperative adhesions.

Prevention of Post-Operative Adhesions: A Comprehensive Review of Present and Emerging Strategies

Post-operative adhesions affect patients undergoing all types of surgeries. They are associated with serious complications, including higher risk of morbidity and mortality. Given increased hospitalization, longer operative times, and longer length of hospital stay, post-surgical adhesions also pose a great financial burden. Although our knowledge of some of the underlying mechanisms driving adhesion formation has significantly improved over the past two decades, literature has yet to fully explain the pathogenesis and etiology of post-surgical adhesions. As a result, finding an ideal preventative strategy and leveraging appropriate tissue engineering strategies has proven to be difficult. Different products have been developed and enjoyed various levels of success along the translational tissue engineering research spectrum, but their clinical translation has been limited. Herein, we comprehensively review the agents and products that have been developed to mitigate post-operative adhesion formation. We also assess emerging strategies that aid in facilitating precision and personalized medicine to improve outcomes for patients and our healthcare system.

Effects of a Thermosensitive Antiadhesive Agent on Single-Row Arthroscopic Rotator Cuff Repair

BACKGROUND

Postoperative stiffness after rotator cuff repair is a common complication that can lead to poor outcomes and patient discomfort. The application of an antiadhesive agent at the time of repair recently became an option for clinicians, but little information is available on its effects.

PURPOSE

To evaluate and compare retear rates, the incidence of postoperative stiffness, and the clinical outcomes of patients who underwent cuff repair with or without the application of an antiadhesive agent.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Among 296 patients who underwent arthroscopic rotator cuff repair surgery, we compared the outcomes of those injected with a thermosensitive gel antiadhesive agent into the subacromial space (112 cases) versus noninjected controls (184 cases). Retear rates in the 2 groups were determined by magnetic resonance imaging at 1 year after surgery. Shoulder joint range of motion and functional scores were evaluated serially.

RESULTS

The rate of retear was significantly lower in the injection group (20/112 cases; 17.9%) than the control group (53/184 cases; 28.8%) (P = .034). Postoperative stiffness was not significantly different between the 2 groups (P = .710). Among the data regarding range of motion, only forward flexion at 6 months after surgery showed superior results in the injection group. Functional scores showed conflicting results: The control group had better visual analog scale scores for pain (injection vs control: 2.17 vs 1.68 at 6 months; 1.82 vs 1.28 at 12 months), American Shoulder and Elbow Surgeons scores (79.89 vs 89.64 at 12 months), and simple shoulder test scores (8.70 vs 10.06 at 12 months), whereas the injection group had better Constant-Murley scores (injection vs control: 59.49 vs 55.60 at 3 months; 77.35 vs 71.98 at 6 months; 87.28 vs 81.56 at 12 months).

CONCLUSION

The tendon healing rate was significantly higher in the group receiving an antiadhesive agent than in the control group. No intergroup difference was seen in the occurrence of postoperative stiffness. However, the pain-related functional score showed inferior results in the injection group at 12 months. The biological action of antiadhesive agents in rotator cuff repair should be further evaluated.

Effect of a poloxamer-based thermosensitive gel on rotator cuff repair in a rabbit model: a controlled laboratory study

BACKGROUND

A common complication after rotator cuff repair is postoperative stiffness, which can be reduced by a simple application of an anti-adhesive agent. However, anti-adhesive agents may affect rotator cuff healing by preventing fibrosis. This experimental animal study evaluated the effect of the application of a poloxamer-based thermosensitive anti-adhesive gel and its influence on the healing of an acute rotator cuff repair in a rabbit model.

METHODS

Acute rotator cuff repair (supraspinatus tendon) was performed using a transosseous suturing method. One shoulder on a randomly selected side was treated with a local application of the anti-adhesive agent (applied side), and saline was applied to the contralateral side (control side). Biomechanical testing and histological analyses were performed at 4 and 8 weeks postoperatively. Eight rabbits were included for each testing and time point, for a total of 32 rabbits.

RESULTS

The failure load at 4 weeks was lower in the experimental group (95.2 ± 19.6 N vs. 110.0 ± 20.5 N; P = 0.017). Conversely, at 8 weeks, the failure load was higher in the experimental group (148.3 ± 16.2 N) than in the control group (122.4 ± 16.9 N; P = 0.002). Histological analyses revealed no statistically significant differences in the tendon maturing scores at 4 and 8 weeks between the two groups (all P > 0.05). The thickness of the fibrosis between the rotator cuff tendon and deltoid was thinner in the experimental group at both time points (0.50 ± 0.25 vs. 1.27 ± 0.47; P = 0.002 at 4 weeks, and 0.37 ± 0.35 vs. 1.39 ± 0.50; P = 0.003 at 8 weeks).

CONCLUSIONS

Application of an anti-adhesive agent in this rotator cuff model confirmed the agent's effectiveness at reducing fibrosis in the subacromial space. The healing of the tendon showed interesting results, as the experimental group had poorer biomechanical strength at 4 weeks but superior strength at 8 weeks.

Decrease in VEGF-Induced Pericardial Adhesion Formation Using Bevacizumab After Surgery

OBJECTIVES

Some degrees of postoperative cardiac adhesions occur in response to the first cardiac surgery in patients that may limit surgeons for subsequent operations and increase the risk of heart injury. In this article, we established a model of postoperative pericardial adhesions, and because vascular endothelial growth factor (VEGF) seems to initiate adhesion formation through inflammatory responses, we used an anti-VEGF antibody, that is, bevacizumab, to examine its effects on postoperative adhesion formation.

METHODS

Twenty Wistar rats were divided in 2 groups: control and bevacizumab. After chest opening, pericardial sac was opened and the heart was fully exposed. In the bevacizumab group, bevacizumab (2.5 mg/kg) was applied locally on the heart and then the chest was closed. The control group received saline solution as placebo. After 42 days, high-sensitivity C-reactive protein in peripheral blood was measured, and re-sternotomy was performed to measure severity of pericardial adhesions. Then, the hearts were collected from all rats to evaluate percentage of CD-31-positive cells (as a marker of angiogenesis) using immunohistochemical staining.

RESULTS

When the bevacizumab group was compared with the control group, we found that the mean score of adhesion (0.89 ± 0.38 vs 2.56 ± 0.41) and CD-31 expression (27.45 ± 3.75% vs 56.26 ± 1.98%) was decreased significantly after bevacizumab administration. However, we did not find any difference in high-sensitivity C-reactive protein levels of control and bevacizumab animals.

CONCLUSION

In the current study, bevacizumab administration could effectively reduce adhesion formation after first sternotomy by preventing VEGF-induced angiogenesis through CD-31 downregulation.

Properties of collagen-based hemostatic patch compared to oxidized cellulose-based patch

Two self-adhering hemostatic patches, based on either PEG-coated collagen (PCC) or PEG-coated oxidized cellulose (PCOC), are compared regarding to maximum burst pressure, mechanical stability, and swelling. In addition, the induction of tissue adhesions by the materials was assessed in a rabbit liver abrasion model. Both materials showed comparable sealing efficacy in a burst pressure test (37 ± 16 vs. 35 ± 8 mmHg, P = 0.730). After incubation in human plasma, PCC retained its mechanical properties over the test period of 8 h, while PCOC showed faster degradation after the 2 h time-point. The degradation led to a significantly decreased force at break (minimum force at break 0.55 N during 8 h for PCC, 0.27 N for PCOC; p < 0.001). Further, PCC allowed significantly higher deformation before break (52% after 4 h and 50% after 8 h for PCC, 18% after 4 h and 23% after 8 h for PCOC; p = 0.003 and p < 0.001 for 4 h and 8 h, respectively) and showed less swelling in human plasma (maximum increase in thickness: ~20% PCC, ~100% PCOC). Faster degradation of PCOC was visible macroscopically and histologically in vivo after 14 days. PCC showed visible structural residues with little cellular infiltration while strong infiltration with no remaining structural material was seen with PCOC. In vivo, a higher incidence of adhesion formation after PCOC application was detected. In conclusion, PCC has more reliable mechanical properties, reduced swelling, and less adhesion formation than PCOC. PCC may offer greater clinical benefit for surgeons in procedures that have potential risk for body fluid leakage or that require prolonged mechanical stability.