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

Polymeric Dural Biomaterials in Spinal Surgery: A Review

Laminectomy is a commonly performed surgical procedure by orthopedic and neurosurgeons, aimed at alleviating nerve compression and reducing pain. However, in some cases, excessive proliferation of fibrous scar tissue in the epidural space post-surgery can lead to persistent and intractable lower back pain, a condition known as Failed Back Surgery Syndrome (FBSS). The persistent fibrous tissue causes both physical and emotional distress for patients and also makes follow-up surgeries more challenging due to reduced visibility and greater technical difficulty. It has been established that the application of biomaterials to prevent epidural fibrosis post-lumbar surgery is more beneficial than revision surgeries to relieve dural fibrosis. Hydrogel-based biomaterials, with their excellent biocompatibility, degradability, and injectability and tunable mechanical properties, have been increasingly introduced by clinicians and researchers. This paper, building on the foundation of epidural fibrosis, primarily discusses the strategies for the preparation of natural and polymeric biomaterials to prevent epidural fibrosis, their physicochemical properties, and their ability to mitigate the excessive proliferation of fibroblasts. It also emphasizes the challenges that need to be addressed to translate laboratory research into clinical practice and the latest advancements in this field.

Types and doses of anti-adhesive agents injected into subacromial space do not have an effect on the clinical and anatomical outcomes after arthroscopic rotator cuff repair

PURPOSE

Joint stiffness after arthroscopic rotator cuff repair is a major concern for orthopaedic surgeons. Various antiadhesive agents are commonly administered after rotator cuff repair for its prevention. This study aimed to compare the outcomes among patients injected with different types and amounts of anti-adhesive agents after rotator cuff repair. It was hypothesized that the outcomes might differ depending on the use of the anti-adhesive agent and its type and dose.

METHODS

A total of 267 patients who underwent arthroscopic rotator cuff repair with or without subacromial injection of anti-adhesive agents were enrolled. The first group (group A; 51 patients) were injected with 3 mL of poloxamer/sodium alginate-based anti-adhesive agent. The second group (group B; 93 patients) were injected with 3 mL of sodium hyaluronate-based anti-adhesive agent. The third group (group C; 82 patients) were injected with 1.5 mL of sodium hyaluronate-based anti-adhesive agent. Finally, the last group (group D; 41 patients) who did not use anti-adhesive agents served as the control. The range of motion (ROM) and pain VAS scores were measured preoperatively and at 5 weeks, 3 months, 6 months, and 1 year postoperatively. Functional outcomes were evaluated using American Shoulder and Elbow Surgeons and Constant scores, whereas cuff integrity was assessed via MRI or ultrasonography at least 6 months postoperatively.

RESULTS

All ROM measurements, pain VAS scores, and functional scores were significantly improved regardless of the use, type, and dose of the anti-adhesive agents. In addition shoulder ROM and rotator cuff healing did not significantly differ among the groups (all n.s.).

CONCLUSIONS

No significant differences were found in the clinical and anatomical outcomes according to the type and dose of the anti-adhesive agents subacromially injected after rotator cuff repair.

LEVEL OF EVIDENCE

III.

Oncological outcomes in fertility-sparing treatment in stage IA-G2 endometrial cancer

Background

The gold standard treatment for early-stage endometrial cancer (EC) is hysterectomy with bilateral salpingo-oophorectomy (BSO) with lymphadenectomy. In selected patients desiring pregnancy, fertility-sparing treatment (FST) can be adopted. Our review aims to collect the most incisive studies about the possibility of conservative management for patients with grade 2, stage IA EC. Different approaches can be considered beyond demolition surgery, such as local treatment with levonorgestrel-releasing intra-uterine device (LNG-IUD) plus systemic therapy with progestins.

Study design

Our systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. PubMed, EMBASE, and Scopus databases were consulted, and five studies were chosen based on the following criteria: patients with a histological diagnosis of EC stage IA G2 in reproductive age desiring pregnancy and at least one oncological outcome evaluated. Search imputes were “endometrial cancer” AND “fertility sparing” AND “oncologic outcomes” AND “G2 or stage IA”.

Results

A total of 103 patients were included and treated with a combination of LNG-IUD plus megestrol acetate (MA) or medroxyprogesterone acetate (MPA), gonadotrophin-releasing hormone (GnRH) plus MPA/MA, hysteroscopic resectoscope (HR), and dilation and curettage (D&C). There is evidence of 70% to 85% complete response after second-round therapy prolongation to 12 months.

Conclusions

Conservative measures must be considered temporary to allow pregnancy and subsequently perform specific counseling to adopt surgery. Fertility-sparing management is not the current standard of care for young women with EC. It can be employed for patients with early-stage diseases motivated to maintain reproductive function. Indeed, the results are encouraging, but the sample size must be increased.

Effect of Poloxamer-Based Thermo-Sensitive Sol-Gel Agent on Upper Limb Dysfunction after Axillary Lymph Node Dissection: A Double-Blind Randomized Clinical Trial

PURPOSE

Restricted shoulder motion is a major morbidity associated with a lower quality of life and disability after axillary lymph node dissection (ALND) in patients with breast cancer. This study sought to evaluate the antiadhesive effect of a poloxamer-based thermosensitive sol-gel (PTAS) agent after ALND.

METHODS

We designed a double-blind, multicenter randomized controlled study to evaluate the clinical efficacy and safety of PTAS in reducing upper-limb dysfunction after ALND. The primary outcome was the change in the range of motion (ROM) of the shoulder before surgery and 4 weeks after ALND (early postoperative period). Secondary outcomes were shoulder ROM at six months, axillary web syndrome, and lymphedema (late postoperative period).

RESULTS

A total of 170 patients with planned ALND were randomly assigned to one of 2 groups (poloxamer and control) and 15 patients were excluded. In the poloxamer group (n = 76), PTAS was applied to the surface of the operative field after ALND. ALND was performed without the use of poloxamer in the control group (n = 79). Relative to the control group, the poloxamer group had significantly lower early postoperative restrictions in total shoulder ROM at four weeks (-30.04 ± 27.76 vs. -42.59 ± 36.79; p = 0.0236). In particular, the poloxamer group showed greater reductions in horizontal abduction at four weeks (-3.92 ± 9.80 vs. -10.25 ± 15.42; p = 0.0050). The ROM of the shoulder at 24 weeks, axillary web syndrome, and lymphedema were not significantly different between the two groups. No adverse effects were observed in either group.

CONCLUSION

We suggest that poloxamer might improve the early postoperative shoulder ROM in patients with breast cancer who have undergone ALND.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02967146.

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.

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.

A Randomized Controlled Trial of Thermo-Sensitive Sol-Gel Anti-Adhesion Agent after Gynecologic Surgery

Postoperative abdominal adhesions can lead to several adverse consequences such as pelvic pain, bowel obstruction, and infertility. We aimed to explore the anti-adhesion efficacy and safety of a thermo-sensitive sol-gel agent in patients who receive abdominopelvic surgery for benign gynecologic disease. This study was a randomized, controlled, single-blind clinical trial of women undergoing benign gynecologic surgery between January 2017 and December 2017. The patients were randomly assigned to three groups with a 1:1:1 ratio: experimental group (received the thermo-sensitive sol-gel agent), control group (untreated), and comparator group (received 4% icodextrin). Patients were followed for 4 weeks postoperatively, and efficacy was evaluated by performing the visceral slide test to identify adhesion formation. In total, 183 patients were enrolled in the study, and 178 (97.3%) completed the trial. The incidence rate of abdominal adhesion formation was significantly lower in the experimental group than in the control group (7.9% vs. 21.1%, p = 0.040); however, it was similar between the experimental and comparator groups (7.9% vs. 13.8%. p = 0.299). At 4 weeks, no differences in adhesion-related symptoms were observed between the experimental and control groups. Adverse events were mostly mild and did not differ significantly among the three groups (p = 0.375). In conclusion, use of a thermo-sensitive sol-gel agent was safe and effective to prevent abdominal adhesions after benign gynecologic surgeries.

Dual dynamically crosslinked thermosensitive hydrogel with self-fixing as a postoperative anti-adhesion barrier

Tissue adhesion is a severe postoperative complication. Various strategies have been developed to minimize postoperative adhesion, but the clinical efficacy is still far from satisfactory. Herein, we present a dual dynamically crosslinked hydrogel to serve as a physical postoperative anti-adhesion barrier. The hydrogel was generated by dynamic chemical oxime bonding from alkoxyamine-terminated Pluronic F127 (AOP127) and oxidized hyaluronic acid (OHA), as well as hydrophobic association of AOP127. Rheological analysis demonstrated that the hydrogel exhibits temperature sensitivity. At 37 °C, it shows much higher modulus and higher stability than the Pluronic F127 hydrogel. Hemolytic assays suggested that the hydrogel undergoes low hemolysis. In addition, it exhibited anti-adhesion to blood cells in blood cell adhesion tests. It also showed an anti-attachment effect to fibroblasts and biocompatibility in vitro cell studies. Macroscopic evaluation and lap-shear tests revealed that the hydrogel has a moderate adhesive capacity to tissue, which is important for self-fixation. A rat model of sidewall defect-bowel abrasion was established to evaluate the anti-adhesion effect in vivo. The gross observation and pathological analysis revealed a significant reduction in postoperative peritoneal adhesion in the AOP127/OHA hydrogel-treated group than those treated with normal saline or Pluronic F127 hydrogel. Hence, the dual dynamically crosslinked hydrogel with self-fixable capacity may be suitable as a physical barrier for postoperative adhesion prevention. STATEMENT OF SIGNIFICANCE: Despite the development of numerous postoperative anti-adhesion barriers, their anti-adhesion efficacy is still limited in clinical trials due to poor tissue adhesion and rapid clearance from injured areas. Herein, we have developed a dual dynamic crosslinked hydrogel, generated by dynamic oxime bonds and hydrophobic interactions. The hydrogel is temperature-sensitive and demonstrates moderate tissue adhesion capacity, which allows for self-fixation when applied to defects. The introduction of dynamic covalent bonds improves the stability of the hydrogel. Moreover, the hydrogel not only displays appropriate hemocompatibility, cytocompatibility and anti-adhesion of blood cells and fibroblasts, but it also effectively contributes to preventing postoperative peritoneal adhesions in vivo. Hence, this dual dynamic crosslinked hydrogel may have potential applications as a physical barrier in clinical practice.

Effects of poloxamer-based thermo-sensitive sol-gel agent on urethral stricture after transurethral resection of the prostate for benign prostatic hyperplasia: a multicentre, single-blinded, randomised controlled trial

OBJECTIVE

To evaluate the effectiveness of poloxamer-based thermo-sensitive sol-gel instillation, after transurethral resection of the prostate (TURP), for preventing urethral stricture.

PATIENTS AND METHODS

In all, 198 patients underwent TURP for benign prostatic hyperplasia. Recruited patients were randomly divided into two groups: groups A and B. Patients in Group A (100 patients, experimental group) received poloxamer-based thermo-sensitive sol-gel instillation and patients in the Group B (98 patients, control group) received lubricant instillation after TURP. Each patient was evaluated at 4 (V1), 12 (V2), and 24 weeks (V3) after TURP. The effectiveness of poloxamer-based thermo-sensitive sol-gel instillation was evaluated based on the International Prostate Symptom Score (IPSS), IPSS-Quality of Life (QoL), Overactive bladder questionnaire (OAB-q), maximum urinary flow rate (Q_max ), post-void residual urine volume (PVR), and cystoscopy.

RESULTS

Amongst the initial 198 participants, 80 patients in Group A and 83 in Group B completed the study. There were no significant differences in IPSS-QoL and OAB-q between the groups. However, Q_max was significantly different between groups A and B, at a mean (SD) of 18.92 (9.98) vs 15.58 (9.24) mL/s (P = 0.028) at 24 weeks after TURP. On cystoscopic examination, urethral stricture after TURP was found in two of the 80 patients in Group A and 10 of 83 in Group B (P = 0.023).

CONCLUSIONS

Poloxamer-based thermo-sensitive sol-gel instillation after TURP lowered the incidence of urethral stricture.

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.

Pregnancy and oncologic outcomes after fertility-sparing management for early stage endometrioid endometrial cancer

OBJECTIVE

Hormonal management is an alternative treatment for preserving fertility in patients with presumed early stage endometrioid endometrial cancer. This study aimed to define the pregnancy and oncologic outcomes and factors of successful conception after hormone therapy for endometrioid endometrial cancer.

METHODS

We retrospectively analyzed patients presumed to have stage IA, grade 1-2 endometrioid endometrial cancer who underwent fertility-sparing treatment. Concurrent medroxyprogesterone and levonorgestrel-release intra-uterine devices were used for treatment. The pregnancy outcomes and oncologic outcomes were compared between the pregnant and non-pregnant groups.

RESULTS

Seventy-one patients presumed to have stage IA, grade 1-2 endometrioid endometrial cancer had complete remission, and 49 of them tried to conceive. Twenty-two (44.9%) patients became pregnant; the total number of pregnancies was 30. These pregnancies resulted in seven abortions (23.3%), one pre-term birth (3.3%), and 20 full-term births (66.6%). The total live birth rate was 66.6 % (20/30). The median duration of hormonal treatment was 11.9 months (range 4-49) and 12.0 months (range 3-35) in the pregnant and non-pregnant groups, respectively. On multivariate analysis, age, body mass index, treatment duration, medroxyprogesterone dose, and number of dilatation and curettage biopsies were not significantly associated with pregnancy failure, but the association with grade (OR 6.2, 95% CI 1.0 to 38.9; P<0.05) was statistically significant. The median disease-free survival duration was 26 months (range 20-38) and 12 months (range 4-48) in the pregnant and non-pregnant groups, respectively (P<0.05, log-rank test).

CONCLUSIONS

A lower grade might be a positive factor for future pregnancy. Moreover, successful pregnancy might be a factor in preventing recurrence.

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.