A thermosensitive chitosan-based hydrogel barrier for post-operative adhesions' prevention

Naturally derived double-network hydrogels with application as flexible adhesive sensors

Hydrogels have been widely used in the biomedical field, including wearable sensors and biological adhesives. However, achieving a balance between various functionalities, such as wet adhesion, stable conductivity, and biocompatibility, in one customized hydrogel has been a challenging issue. In this study, we developed a multifunctional hydrogel comprising recombinant human collagen (RHC) and aldehyde-modified sodium alginate (Ald-alginate), which was primarily crosslinked through a Schiff-base reaction and metal chelation. Due to the combination of a dynamic covalent crosslinking network (imine linkage between RHC and Ald-alginate) and a dynamic ionic crosslinking network (ionic bonding between Ca2+ and Ald-alginate), the hydrogel exhibited excellent self-healing and injectable behaviors. Benefiting from the high Ca2+ content, the hydrogel also attained antifreezing and conductivity properties. In addition to its excellent conductivity and biocompatibility, the hydrogel exhibited strong wet tissue adhesion ability and could adhere rapidly and strongly to the surfaces of various objects or biological tissues, forming a good sealing environment. Moreover, the hydrogel could be directly adhered to a tissue surface as a flexible sensor to accurately detect physiological signals. The versatility of this multifunctional hydrogel will open new avenues for biomedical applications, such as bioadhesives and biosensing.

Injectable polyamide-amine dendrimer-crosslinked meloxicam-containing poly-γ-glutamic acid hydrogel for prevention of postoperative tissue adhesion through inhibiting inflammatory responses and balancing the fibrinolytic system

Establishing a physical barrier between the peritoneum and the cecum is an effective method to reduce the risk of postoperative abdominal adhesions. Meloxicam (MX), a nonsteroidal anti-inflammatory drug has also been applied to prevent postoperative adhesions. However, its poor water solubility has led to low bioavailability. Herein, we developed an injectable hydrogel as a barrier and drug carrier for simultaneous postoperative adhesion prevention and treatment. A third-generation polyamide-amine dendrimer (G3) was exploited to dynamically combine with MX to increase the solubility and the bioavailability. The formed G3@MX was further used to crosslink with poly-γ-glutamic acid (γ-PGA) to prepare a hydrogel (GP@MX hydrogel) through the amide bonding. In vitro and in vivo experiments evidenced that the hydrogel had good biosafety and biodegradability. More importantly, the prepared hydrogel could control the release of MX, and the released MX is able to inhibit inflammatory responses and balance the fibrinolytic system in the injury tissues in vivo. The tunable rheological and mechanical properties (compressive moduli: from ∼ 57.31 kPa to ∼ 98.68 kPa;) and high anti-oxidant capacity (total free radical scavenging rate of ∼ 94.56 %), in conjunction with their syringeability and biocompatibility, indicate possible opportunities for the development of advanced hydrogels for postoperative tissue adhesions management.

Effect of a Thermosensitive Hydroxybutyl Chitosan Hydrogel on Postoperative Sequalae and Quality of Life After Impacted Mandibular Third Molar Extraction

BACKGROUND

Third molar (M3) extraction is a common surgery in oral and maxillofacial surgery, and composite wound dressings such as hydroxybutyl chitosan (HBC) may improve postoperative sequala following M3 removal.

PURPOSE

The study purpose was to measure and compare differences in pain, swelling, trismus, wound healing, and quality of life (QOL) between the HBC and the control sides in patients undergoing M3 removal.

STUDY DESIGN, SETTING, SAMPLE

This study is a double-blind, split-mouth, randomized clinical trial. Patients who required M3 removal between June 2022 and May 2023 were included. Exclusion criteria included seafood allergies, smoking, poor oral hygiene, and systemic diseases.

PREDICTOR VARIABLE

The predictor variable was the socket treatment technique. Subjects were randomly assigned to the HBC or control (physiological saline) side.

MAIN OUTCOME VARIABLE

The primary outcome variables, including pain assessed by visual analog scale, swelling, and maximal incisional opening, were measured on the first, third, and seventh postoperative days. The secondary outcome variables included QOL and wound healing score measured on the third and seventh days after surgery.

COVARIATES

The covariates included age, sex, and operation time.

ANALYSES

The Shapiro‒Wilk test was used to evaluate the normality of the data distribution. The paired t test or Wilcoxon signed-rank test was adopted. Statistical significance was set at P < .05.

RESULTS

The study included 60 patients (mean age: 25.81 ± 4.91; 23 (38%) males, 37 (62%) females). A statistically significant difference in the level of pain (HBC: 37.58 ± 4.39 mm, control: 47.00 ± 4.33 mm, day 1, P < .001; 21.88 ± 3.25 mm, 35.95 ± 1.57 mm, day 3, P < .001), maximal incisional opening (23.92 ± 1.38 mm, 18.22 ± 1.82 mm, day 1, P < .001; 30.00 ± 1.61 mm, 23.78 ± 1.70 mm, day 3, P < .001), and swelling (6.86 ± 0.70 mm, 7.15 ± 0.80 mm, day 3, P = .006) was detected after surgery. A statistically significant difference in QOL was detected (HBC: 13.70 ± 1.65, control: 18.60 ± 2.14, day 3, P < .001).

CONCLUSION AND RELEVANCE

The application of HBC hydrogels to wounds after impacted mandibular M3 extraction reduces postoperative sequalae, promotes wound healing and improves postoperative QOL.

Neutrophil Extracellular Traps: A Crucial Factor in Post-Surgical Abdominal Adhesion Formation

Post-surgical abdominal adhesions, although poorly understood, are highly prevalent. The molecular processes underlying their formation remain elusive. This review aims to assess the relationship between neutrophil extracellular traps (NETs) and the generation of postoperative peritoneal adhesions and to discuss methods for mitigating peritoneal adhesions. A keyword or medical subject heading (MeSH) search for all original articles and reviews was performed in PubMed and Google Scholar. It included studies assessing peritoneal adhesion reformation after abdominal surgery from 2003 to 2023. After assessing for eligibility, the selected articles were evaluated using the Critical Appraisal Skills Programme checklist for qualitative research. The search yielded 127 full-text articles for assessment of eligibility, of which 7 studies met our criteria and were subjected to a detailed quality review using the Critical Appraisal Skills Programme (CASP) checklist. The selected studies offer a comprehensive analysis of adhesion pathogenesis with a special focus on the role of neutrophil extracellular traps (NETs) in the development of peritoneal adhesions. Current interventional strategies are examined, including the use of mechanical barriers, advances in regenerative medicine, and targeted molecular therapies. In particular, this review emphasizes the potential of NET-targeted interventions as promising strategies to mitigate postoperative adhesion development. Evidence suggests that in addition to their role in innate defense against infections and autoimmune diseases, NETs also play a crucial role in the formation of peritoneal adhesions after surgery. Therefore, therapeutic strategies that target NETs are emerging as significant considerations for researchers. Continued research is vital to fully elucidate the relationship between NETs and post-surgical adhesion formation to develop effective treatments.

A Graphene Composite Film Based Wearable Far-Infrared Therapy Apparatus (GRAFT) for Effective Prevention of Postoperative Peritoneal Adhesion

Postoperative peritoneal adhesion (PPA) is the most frequent complication after abdominal surgery. Current anti-adhesion strategies largely rely on the use of physical separating barriers creating an interface blocking peritoneal adhesion, which cannot reduce inflammation and suffers from limited anti-adhesion efficacy with unwanted side effects. Here, by exploiting the alternative activated macrophages to alleviate inflammation in adhesion development, a flexible graphene-composite-film (F-GCF) generating far-infrared (FIR) irradiation that effectively modulates the macrophage phenotype toward the anti-inflammatory M2 type, resulting in reduced PPA formation, is designed. The anti-adhesion effect of the FIR generated by F-GCF is determined in the rat abdominal wall abrasion-cecum defect models, which exhibit reduced incidence and area of PPA by 67.0% and 92.1% after FIR treatment without skin damage, significantly superior to the clinically used chitosan hydrogel. Notably, within peritoneal macrophages, FIR reduces inflammation reaction and promotes tissue plasminogen activator (t-PA) level via the polarization of peritoneal macrophages through upregulating Nr4a2 expression. To facilitate clinical use, a wirelessly controlled, wearable, F-GCF-based FIR therapy apparatus (GRAFT) is further developed and its remarkable anti-adhesion ability in the porcine PPA model is revealed. Collectively, the physical, biochemical, and in vivo preclinical data provide compelling evidence demonstrating the clinical-translational value of FIR in PPA prevention.

Acellular embryoid body and hydroxybutyl chitosan composite hydrogels promote M2 macrophage polarization and accelerate diabetic cutaneous wound healing

Diabetic wound healing is delayed due to persistent inflammation, and macrophage-immunomodulating biomaterials can control the inflammatory phase and shorten the healing time. In this study, acellular embryoid bodies (aEBs) were prepared and mixed with thermosensitive hydroxybutyl chitosan (HBC) hydrogels to produce aEB/HBC composite hydrogels. The aEB/HBC composite hydrogels exhibited reversible temperature-sensitive phase transition behavior and a hybrid porous network. In vitro analysis showed that the aEB/HBC composite hydrogels exhibited better antimicrobial activity than the PBS control, aEBs or HBC hydrogels and promoted M0 to M2 polarization but not M1 to M2 macrophage repolarization in culture. The in vivo results showed that the aEB/HBC composite hydrogels accelerated cutaneous wound closure, re-epithelialization, ingrowth of new blood vessels, and collagen deposition and reduced the scar width during wound healing in diabetic mice over time. Macrophage phenotype analysis showed that the aEB/HBC composite hydrogels induce M2 macrophage reactions continually, upregulate M2-related mRNA and protein expression and downregulate M1-related mRNA and protein expression. Therefore, the aEB/HBC composite hydrogels have excellent antimicrobial activity, promote M2 macrophage polarization and accelerate the functional and structural healing of diabetic cutaneous wounds.

Polysaccharide-based hydrogels for medical devices, implants and tissue engineering: A review

Hydrogels are highly biocompatible biomaterials composed of crosslinked three-dimensional networks of hydrophilic polymers. Owing to their natural origin, polysaccharide-based hydrogels (PBHs) possess low toxicity, high biocompatibility and demonstrate in vivo biodegradability, making them great candidates for use in various biomedical devices, implants, and tissue engineering. In addition, many polysaccharides also show additional biological activities such as antimicrobial, anticoagulant, antioxidant, immunomodulatory, hemostatic, and anti-inflammatory, which can provide additional therapeutic benefits. The porous nature of PBHs allows for the immobilization of antibodies, aptamers, enzymes and other molecules on their surface, or within their matrix, potentiating their use in biosensor devices. Specific polysaccharides can be used to produce transparent hydrogels, which have been used widely to fabricate ocular implants. The ability of PBHs to encapsulate drugs and other actives has been utilized for making neural implants and coatings for cardiovascular devices (stents, pacemakers and venous catheters) and urinary catheters. Their high water-absorption capacity has been exploited to make superabsorbent diapers and sanitary napkins. The barrier property and mechanical strength of PBHs has been used to develop gels and films as anti-adhesive formulations for the prevention of post-operative adhesion. Finally, by virtue of their ability to mimic various body tissues, they have been explored as scaffolds and bio-inks for tissue engineering of a wide variety of organs. These applications have been described in detail, in this review.

Biocompatible Nanocomposites for Postoperative Adhesion: A State-of-the-Art Review

To reduce and prevent postsurgical adhesions, a variety of scientific approaches have been suggested and applied. This includes the use of advanced therapies like tissue-engineered (TE) biomaterials and scaffolds. Currently, biocompatible antiadhesive constructs play a pivotal role in managing postoperative adhesions and several biopolymer-based products, namely hyaluronic acid (HA) and polyethylene glycol (PEG), are available on the market in different forms (e.g., sprays, hydrogels). TE polymeric constructs are usually associated with critical limitations like poor biocompatibility and mechanical properties. Hence, biocompatible nanocomposites have emerged as an advanced therapy for postoperative adhesion treatment, with hydrogels and electrospun nanofibers among the most utilized antiadhesive nanocomposites for in vitro and in vivo experiments. Recent studies have revealed that nanocomposites can be engineered to generate smart three-dimensional (3D) scaffolds that can respond to different stimuli, such as pH changes. Additionally, nanocomposites can act as multifunctional materials for the prevention of adhesions and bacterial infections, as well as tissue healing acceleration. Still, more research is needed to reveal the clinical potential of nanocomposite constructs and the possible success of nanocomposite-based products in the biomedical market.

Chitosan-based hydrogel wound dressing: From mechanism to applications, a review

As promising biomaterials, hydrogels are widely used in the medical engineering field, especially in wound repairing. Compared with traditional wound dressings, such as gauze and bandage, hydrogel could absorb and retain more water without dissolving or losing its three-dimensional structure, thus avoiding secondary injury and promoting wound healing. Chitosan and its derivatives have become hot research topics for hydrogel wound dressing production due to their unique molecular structure and diverse biological activities. In this review, the mechanism of wound healing was introduced systematically. The mechanism of action of chitosan in the first three stages of wound repair (hemostasis, antimicrobial properties and progranulation), the effect of chitosan deacetylation and the molecular weight on its performance are analyzed. Additionally, the recent progress in intelligent and drug-loaded chitosan-based hydrogels and the features and advantages of chitosan were discussed. Finally, the challenges and prospects for the future development of chitosan-based hydrogels were discussed.

Injectable adhesive self-healing biocompatible hydrogel for haemostasis, wound healing, and postoperative tissue adhesion prevention in nephron-sparing surgery

Nephron-sparing surgery is a well-established treatment in patients with T1a renal cell carcinoma; however, the complex suturing process prolongs warm ischaemia time, affects the preservation of normal renal parenchymal function, and causes avoidable postoperative tissue adhesion complications, including chronic abdominal pain, intestinal obstruction, and female infertility. Hence, the design of multifunctional biomaterials with haemostasis, postoperative wound management, and postoperative tissue adhesion prevention properties for nephron-sparing surgeries is urgently needed. In this study, a series of injectable adhesive multifunctional biocompatible hydrogels were designed based on the free-radical polymerisation of monomers acryloyl-6-aminocaproic acid (AA) and N-acryloyl 2-glycine (NAG), and the ionic coordination between Ca²⁺ and the abundant carboxyl groups in AA and NAG. AA/NAG/Ca (AA, NAG, and Ca refer to acryloyl-6-aminocaproic acid, N-acryloyl 2-glycine and calcium chloride, respectively) hydrogel exhibited good mechanical properties, swelling and adhesion properties, flexibility, in vitro blood-clotting ability, and cytocompatibility. In vivo experiments on liver injury models and rat/rabbit nephron-sparing surgery models elucidated that the AA/NAG/Ca hydrogel had haemostasis performance and wound healing properties that led to short bleeding time, reduced bleeding volume, and well-organised nephron structures. An abdomen-caecum adhesion model indicated that the AA/NAG/Ca hydrogel showed excellent anti-adhesion properties. In summary, this multifunctional hydrogel exhibited potential for improving haemostasis and wound management in nephron-sparing surgeries, showing potential for clinical application. STATEMENT OF SIGNIFICANCE: Extended warm ischemia time during nephron sparing surgery negatively affected postoperative renal function due to the need for hemostasis at the wound with abundant blood supply, and postoperative wound healing and additional adhesions caused by the surgical procedure deserve attention. Based on the efficient and stable adhesion properties of hydrogels and the ability to promote wound healing. Herein, a series of adhesive self-healing biocompatible hydrogels were prepared based on free-radical polymerization of acryloyl-6-aminocaproic acid (AA) and N-acryloyl 2-glycine (NAG) and the ionic coordination between Ca²⁺ with the abundant carboxyl groups in AA and NAG. AA/NAG/Ca hydrogel showed hemostasis property in nephron sparing surgery model, promote kidney wound healing, and could perform anti-postoperative adhesion efficacy in an abdomen-caecum adhesion model.

The complex hydrogel based on diatom biosilica and hydroxybutyl chitosan for wound healing

In this study, doxycycline (DOXY)-loaded diatom biosilica (DBs) were developed and coated with hydroxybutyl chitosan (HBC) hydrogel for wound healing. The HBC/DBs/DOXY composite hydrogel had significant inhibitory activity against S. aureus (100%) and E. coli (98%). In addition, the HBC/DBs/DOXY hydrogel showed minimum cytotoxicity on L929 cells in vitro, indicating the great biocompatibility of the composite hydrogel. The in vivo results demonstrated that HBC/DBs/DOXY composite hydrogel could promote the wound re-epithelialization and accelerate the healing. The wound closure was evaluated to be 99.4 ± 0.4% at day 12 after treated with the hydrogel, with the presence of neovascularization and collagen deposition, all indicating the great potential of HBC/DBs/DOXY hydrogel in wound healing.

Barrier materials for prevention of surgical adhesions: systematic review

BACKGROUND

Postoperative surgical adhesions constitute a major health burden internationally. A wide range of materials have been evaluated, but despite constructive efforts and the obvious necessity, there remains no specific barrier widely utilized to prevent postoperative adhesion formation. The aim of this study was to highlight and characterize materials used for prevention of postoperative surgical adhesions in both animal and human studies.

METHODS

A systematic review was performed of all original research articles presenting data related to the prevention of postoperative adhesions using a barrier agent. All available observational studies and randomized trials using animal models or human participants were included, with no restrictions related to type of surgery. PubMed and Embase databases were searched using key terms from inception to August 2019. Standardized data collection forms were used to extract details for each study and assess desirable characteristics of each barrier and success in animal and/or human studies.

RESULTS

A total of 185 articles were identified for inclusion in the review, with a total of 67 unique adhesion barrier agents (37 natural and 30 synthetic materials). Desirable barrier characteristics of an ideal barrier were identified on review of the literature. Ten barriers achieved the primary outcome of reducing the incidence of postoperative adhesions in animal studies followed with positive outputs in human participants. A further 48 materials had successful results from animal studies, but with no human study performed to date.

DISCUSSION

Multiple barriers showed promise in animal studies, with several progressing to success, and fulfilment of desirable qualities, in human trials. No barrier is currently utilized commonly worldwide, but potential barriers have been identified to reduce the burden of postoperative adhesions and associated sequelae.

Electrical signals regulate the release of insulin from electrodeposited chitosan composite hydrogel: An in vitro and in vivo study

Electrical signal controlled drug release from polymeric drug delivery system provides an efficient way for accurate and demandable drug release. In this work, insulin was loaded on inorganic nanoplates (layered double hydroxides, LDHs) and coated on a copper wire by co-electrodeposition with chitosan. The formed structure in chitosan composite hydrogel entrapped insulin efficiently, which were proved by various techniques. In addition, the drug loaded chitosan composite hydrogel demonstrated good biocompatibility as suggested by cell attachment. In vitro drug release experiment showed fast responsive pulsed release of insulin by biasing electrical signals. The in vivo experiment in diabetic rats revealed controllable insulin release in plasma and stable decrease of blood glucose can be achieved by using appropriate electrical signal. In addition, HE staining suggested negligible effect to the tissue by electrical signals. This work suggests that the electrical signal controlled insulin release from chitosan composited hydrogel may be a promising administration route for insulin.

Biomedyczne właściwości chitozanu – zastosowanie w inżynierii tkankowej Biomedical properties of chitosan: Application in tissue engineering

Inżynieria tkankowa to interdyscyplinarna dziedzina badań, która stosuje zasady inżynierii i nauk przyrodniczych do opracowywania substytutów biologicznych, przywracania, utrzymywania lub poprawy funkcji tkanek. Łączy medycy-nę kliniczną, inżynierię mechaniczną, materiałoznawstwo i biologię molekularną. Chitozan jest związkiem, który może być stosowany na szeroką skalę w biomedycynie, m.in. jako nośnik leków, nici chirurgiczne, materiały opatrunkowe przeznaczone do przyspieszonego gojenia ran oraz rusztowania komórkowe w inżynierii tkankowej. Chitozon spełnia najważniejsze kryteria dla biomateriałów, m.in. kompatybilność, odpowiednie właściwości mechaniczne, morfologia i porowatość, nietoksyczność i biodegradowalność. Rusztowania chitozanowe mogą sprzyjać adhezji, różnicowaniu i proliferacji na powierzchni komórek. Z chitozanu można tworzyć różne formy funkcjonalne w zależności od potrzeb i wymagań, w tym: hydrożele 3D, gąbki 3D, folie i membrany oraz nanowłókna. Ze względu na unikalne właściwości fizykochemiczne biopolimer ten może być również wykorzystany do oczyszczania białek terapeutycznych z endotoksyn bakteryjnych, co jest dziś istotnym problemem w oczyszczaniu produktu końcowego w zastosowaniach medycznych. Obecnie terapie oparte na białkach rekombinowanych znajdują szerokie zastosowanie w terapiach celowanych, inżynierii tkankowej oraz szeroko pojętej medycynie regeneracyjnej. Dlatego tak ważny jest współistniejący, dobrze zapro-jektowany system oczyszczania produktu białkowego, który nie zmieni swoich zasadniczych właściwości. Artykuł jest przeglądem aktualnych badań nad zastosowaniem materiałów bioaktywnych na bazie chitozanu w medycynie regene-racyjnej różnych tkanek i narządów (m.in. tkanki chrzęstnej i kostnej, tkanki skórnej czy tkanki nerwowej).

Treatment of Dry Eye With Intracanalicular Injection of Hydroxybutyl Chitosan: A Prospective Randomized Clinical Trial

Background: Punctal/intracanalicular plugs on the market nowadays are all designed before clinical use in treating dry eye disease (DED). To provide an individualized lacrimal drainage system occlusion method and reduce the complications, we developed a “liquid plug” strategy by intracanalicular injection of hydroxybutyl chitosan (HBC) solution, a thermosensitive, phase-changing biomaterial. This study evaluated the efficacy and safety of the HBC plug in treating dry eye disease by comparing it with the VisiPlug absorbable intracanalicular plug.

Methods: A monocenter, randomized, controlled clinical trial was performed. Fifty patients with DED were randomized 1:1 to undergo either the HBC injection treatment or the VisiPlug treatment. Ocular Surface Disease Index (OSDI) questionnaire, tear break-up time (TBUT), corneal fluorescence staining (CFS), tear meniscus height (TMH), and phenol red thread test were evaluated at Day 0 (baseline, before treatment) and Weeks 1, 4, and 12.

Results: The two groups had a balanced baseline of age, gender, and DED-related characteristics. Both occlusion methods could relieve the symptoms and signs of DED. Significant improvement was found in OSDI, phenol red thread test, and tear meniscus height (P < 0.05 compared to baseline) but not in corneal fluorescence staining and tear break-up time (P > 0.05). There is no statistically significant difference between HBC injection and VisiPlug at Weeks 1 and 4 (P > 0.05). However, at week 12, the HBC injection was not as effective as the VisiPlug in maintaining phenol red thread test (HBC: 5.35 ± 3.22 mm, VisiPlug: 8.59 ± 4.35 mm, P = 0.009) and tear meniscus height (HBC: 206.9 ± 47.95 μm, VisiPlug: 242.59 ± 60.30 μm, P = 0.041). The numbers of ocular adverse events were relatively low in both groups.

Conclusions: The HBC injection showed similar efficacy and safety compared to VisiPlug. The intracanalicular injection of HBC solution proves to be a promising, individualizing method to treat DED.

Clinical Trial Registration: This study is registered with the Chinese Clinical Trial Registry (https://www.chictr.org.cn/enindex.aspx), Identifier: ChiCTR1800016603.

Physically Cross-Linked Hyaluronan-Based Ultrasoft Cryogel Prepared by Freeze-Thaw Technique as a Barrier for Prevention of Postoperative Adhesions

Postsurgical peritoneal adhesions are a common and serious postoperative complication after various peritoneal surgeries, such as pelvic and abdominal surgery. Various studies have shown that peritoneal adhesions can be minimized or prevented by physical anti-adhesion barriers, including membranes, knits, and hydrogels. Hydrogels have attracted great attention in preventing peritoneal adhesions because the dimensional architecture of hydrogels is similar to that of the native extracellular matrix. However, chemical cross-linkers had to be used in the preparation of chemical hydrogels, which may have problems in cytotoxicity or unwanted side effects. This fact prompts us to create alternative cross-linking methods for the development of biocompatible hydrogels as physical barriers. Herein, we report a physically cross-linked flexible hyaluronan (HA) cryogel prepared via a freeze-thaw technique as a novel anti-adhesion biomaterial for completely preventing postsurgical peritoneal adhesions. In vitro studies demonstrated that this physically cross-linked HA cryogel exhibited excellent biocompatibility, the inherently desirable biocompatibility and functionality of HA being integrally retained as much as possible. Intriguingly, the rheological properties and appropriate biodegradability of the cryogels were readily tailored and tunable by way of the gelation process. In vivo assessments suggested that the cryogel, as a physical barrier, satisfactorily prevented fibroblast penetration and attachment between the injured tissues and nearby normal organs. Furthermore, the molecular mechanism studies revealed that the HA cryogel could prevent peritoneal adhesion by inhibiting inflammatory response and modulation of the fibrinolytic system. Our results show that HA ultrasoft cryogel is a promising clinical candidate for prolonged adhesion prevention.

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.

Chitosan-centered nanosystems as sustained therapeutics for allergic rhinitis intervention: Inhibition of histamine-induced cascades

Allergic rhinitis (AR), histamine-mediated upper airway inflammatory disorder, is characterized by sneezing, itching, airway hyperreactivity, etc. Though it is clinically well-managed by non-invasive inhaled antihistamines, for example, ketotifen (KT, histamine release inhibitor) and cetirizine (CTZ, histamine receptor antagonist), inherent defects of short mucosal in situ retention, frequent administration resulting in irritation to mucosa, and lack of target-specific sequential release of dual drug systems which have been proven to be more effective are inevitable, urging for alternative therapeutic strategies. Recent advances in nanotechnology may be pivotal to generating muco-adhesive nanosystems, which is desirable to prolong local retention, reduce dosing frequency and relieve mucosal irritation. In this regard, KT incorporated and CTZ decorated hydroxybutyl chitosan nanoparticles (K ⊂ CH NPs) were fabricated as nasal adaptive sequential release dual drug system for long-term AR therapy. Nasal adaptive morphology transformation and two-step payload release up to 72 h were achieved in vitro, with ~ 3-fold higher bio-adhesivity over free drugs appeared. K ⊂ CH NPs accomplished longer histamine release inhibition (~ 24 h) and histamine H₁ receptor antagonism (~ 6 h), compared with free KT&CTZ of ~ 12 h and ~ 2 h, respectively. The nanosystems provided comparable anti-allergic effect to free antihistamines via successive intranasal dropping in AR rat, while encouragingly, significantly (P < 0.05) better therapeutic efficacy at reduced treatment frequency (every 4 days) and dose (half-dose). Therefore, the outcomes establish K ⊂ CH NPs as effective low-dose and long-interval administered nanosystems to ameliorate histamine-mediated AR inflammation, which could in principal find extensive utilizations in respiratory allergy intervention.

Postoperative Adhesion Prevention Using a Biodegradable Temperature-Responsive Injectable Polymer System and Concomitant Effects of the Chymase Inhibitor

Postoperative adhesion remains a problem in surgery and causes postoperative complications. Laparoscopic surgery is now common, making it increasingly important to develop injectable formulations of adhesion barriers that can be applied during such surgeries. Temperature-responsive injectable polymer (IP) systems exhibiting a sol-to-gel transition in response to temperature are promising candidates as effective adhesion barriers that can be applied conveniently during laparoscopic surgery. We previously developed IP systems exhibiting temperature-responsive irreversible gelation based on a triblock copolymer of poly(ε-caprolactone-co-glycolic acid) (PCGA) and poly(ethylene glycol) (PEG) (PCGA-b-PEG-b-PCGA: tri-PCG) and a tri-PCG derivative with acrylate groups at the termini (tri-PCG-acryl). A mixture of tri-PCG-acryl micelle solution and tri-PCG micelle solution containing polythiol exhibited an irreversible sol-to-gel transition in response to a temperature increase. The gel contains partial covalent cross-linking, and the degradation and physical properties of these IP hydrogels can easily be controlled by changing the mixing ratio of tri-PCG-acryl in the formulation. In this study, we investigated the effect of physical properties of the IP hydrogel on the efficacy of adhesion prevention using our IP system containing various amounts of tri-PCG-acryl. Our results show that an IP system with lower physical strength and rapid degradation reduces adhesion more effectively. Chymase plays a crucial role in exacerbating adhesion formation, and a peptide derivative-type chymase inhibitor (CI), Suc-Val-Pro-Phe^P(OPh)₂, was previously reported to prevent adhesion. We thus investigated the concomitant use of this CI with our IP system using two methods: separate administration of the CI and IP and entrapping the CI in the IP hydrogel. IP systems with separately administrated CI provided better results than the administration of an IP system entrapping the CI or sole IP systems. These findings suggest that the pharmacological effect of the CI and a physical barrier generated by our IP system effectively prevents adhesion.

Advancement of Biomaterial-Based Postoperative Adhesion Barriers

Postoperative peritoneal adhesion (PPA) is a prevalent incidence that generally happens during the healing process of traumatized tissues. It causes multiple severe complications such as intestinal obstruction, chronic abdominal pain, and female infertility. To prevent PPA, several antiadhesion materials and drug delivery systems composed of biomaterials are used clinically, and clinical antiadhesive is one of the important applications nowadays. In addition to several commercially available materials, like film, spray, injectable hydrogel, powder, or solution type have been energetically studied based on natural and synthetic biomaterials such as alginate, hyaluronan, cellulose, starch, chondroitin sulfate, polyethylene glycol, polylactic acid, etc. Moreover, many kinds of animal adhesion models, such as cecum abrasion models and unitary horn models, are developed to evaluate new materials' efficacy. A new animal adhesion model based on hepatectomy and conventional animal adhesion models is recently developed and a new adhesion barrier by this new model is also developed. In summary, many kinds of materials and animal models are studied; thus, it is quite important to overview this field's current progress. Here, PPA is reviewed in terms of the species of biomaterials and animal models and several problems to be solved to develop better antiadhesion materials in the future are discussed.

Composite Hydrogel of Methacrylated Hyaluronic Acid and Fragmented Polycaprolactone Nanofiber for Osteogenic Differentiation of Adipose-Derived Stem Cells

Composite hydrogels with electrospun nanofibers (NFs) have recently been used to mimic the native extracellular matrix. In this study, composite hydrogels of methacrylated hyaluronic acid containing fragmented polycaprolactone NFs were used for bone tissue engineering. The composite (NF/hydrogel) was crosslinked under ultraviolet (UV) light. The incorporation of fragmented polycaprolactone NFs increased the compression modulus from 1762.5 to 3122.5 Pa. Subsequently, adipose-derived stem cells incorporated into the composite hydrogel exhibited a more stretched and elongated morphology and osteogenic differentiation in the absence of external factors. The mRNA expressions of osteogenic biomarkers, including collagen 1 (Col1), alkaline phosphatase, and runt-related transcription factor 2, were 3-5-fold higher in the composite hydrogel than in the hydrogel alone. In addition, results of the protein expression of Col1 and alizarin red staining confirmed osteogenic differentiation. These findings suggest that our composite hydrogel provides a suitable microenvironment for bone tissue engineering.

Biomaterials to Prevent Post-Operative Adhesion

Surgery is performed to treat various diseases. During the process, the surgical site is healed through self-healing after surgery. Post-operative or tissue adhesion caused by unnecessary contact with the surgical site occurs during the normal healing process. In addition, it has been frequently found in patients who have undergone surgery, and severe adhesion can cause chronic pain and various complications. Therefore, anti-adhesion barriers have been developed using multiple biomaterials to prevent post-operative adhesion. Typically, anti-adhesion barriers are manufactured and sold in numerous forms, such as gels, solutions, and films, but there are no products that can completely prevent post-operative adhesion. These products are generally applied over the surgical site to physically block adhesion to other sites (organs). Many studies have recently been conducted to increase the anti-adhesion effects through various strategies. This article reviews recent research trends in anti-adhesion barriers.

Thermoresponsive Chitosan/DOPA-Based Hydrogel as an Injectable Therapy Approach for Tissue-Adhesion and Hemostasis

Chitosan (CS) hydrogels are widely used in wound hemostatic agents due to their superior biocompatibility, biodegradability, and hemostatic effect. However, most of them fail to achieve great hemostatic effect because of poor adhesion to bleeding tissues. Also, the conventional implantation surgery of hemostatic hydrogels to internal bleeding wounds may cause secondary trauma to the human body. In this work, catechol-hydroxybutyl chitosan (HBCS-C) has been designed and prepared by grafting hydroxybutyl groups and catechol groups to the CS backbones. The multifunctional HBCS-C hydrogels are fabricated with the properties of thermosensitivity, injectability, tissue-adhesion, biodegradation, biocompatibility, and wound hemostasis. They exhibit excellent liquid-gel transition at different temperatures, through the changes of hydrophilic-hydrophobic interaction and hydrogen bonds generating from hydroxybutyl groups. By the multiple interactions between catechol groups/amino groups and tissues, the biocompatible hydrogels can strongly adhere on the surface of tissue. To further study, the bleeding rat-liver models are made to evaluate the hemostatic effects. After injecting the hydrogel precursor solution into the rat body, the hydrogels are not only formed in situ within 30 s but are also firmly adhered to the bleeding tissues which shows effective hemostasis. The injectability and tissue-adhesion improvement in this study gives a new insight into hemostatic agents, and the multifunctional hydrogels have a great potential in the biomedical application.

Sustained release of human platelet lysate growth factors by thermosensitive hydroxybutyl chitosan hydrogel promotes skin wound healing in rats

This study evaluated the effect of thermosensitive hydroxybutyl chitosan (HBC) hydrogel loaded with human platelet lysate (hPL) on skin wound healing in rats. hPLs were generated by freeze-thaw method of platelet-rich plasma from healthy donors. Successful grafting of hydroxybutyl group to chitosan molecular chain to obtain HBC hydrogel was confirmed by Fourier-transform infrared spectroscopy. HBC/hPL was prepared by combining 10% (vol/vol) hPL with HBC solution. Surface morphologies were determined by Scanning Electron Microscopy, rheological properties were measured by rheometer, and sustained release of factors from HBC/hPL was measured by enzyme-linked immunoassay. We evaluated the in vitro effect of HBC/hPL on human umbilical cord vein endothelial cell (HUVEC) proliferation, migration, and tube formation. The effect of growth factors released from HBC/hPL in promoting skin wound healing was evaluated by gross observation, histology, immunohistochemistry, and immunofluorescence in vivo. Rheological analyses indicated the gelation temperatures of HBC and HBC/hPL were 17 and 14°C, respectively. ELISA showed sustained release of human platelet-derived growth factor, basic fibroblast growth factor, and transforming growth factor-β1 from HBC/hPL hydrogel. In vitro studies revealed HBC/hPL promoted greater levels of HUVECs proliferation, migration, and tube formation than the HBC and control groups. In vivo studies showed better wound healing, greater amounts of newly formed collagen, as well as neovascular and neo-epidermis markers in the wound site of HBC/hPL-treated group compared to the HBC and control groups. HBC/hPL is a promising potential therapeutic agent for promoting skin wound healing via the sustained release of growth factors.

HBC-nanofiber hydrogel scaffolds with 3D printed internal microchannels for enhanced cartilage differentiation

HBC-nanofiber hydrogel scaffolds with 3D printed internal microchannels have been developed to provide a multifunctional biomimetic microenvironment for hMSC chondrogenesis.

Hydrogel scaffolds for tissue engineering: the importance of polymer choice

We explore the design and synthesis of hydrogel scaffolds for tissue engineering from the perspective of the underlying polymer chemistry. The key polymers, properties and architectures used, and their effect on tissue growth are discussed.

Gastric environment-stable oral nanocarriers for in situ colorectal cancer therapy

Colorectal cancer (CRC) is a prevalent and fatal cancer. Oral administration provided the potential for in situ treatment of the colorectal cancer. However, drugs couldn't be well-absorbed mainly due to its degradation in the gastric area and poor intestinal permeability. In this study, we synthesized deoxycholic acid and hydroxybutyl decorated chitosan nanoparticles (DAHBC NPs) as oral curcumin (CUR) delivery system for colorectal cancer treatment. DAHBC with lower critical solution temperature (LCST) below 37 °C (27-33 °C) was obtained. DAHBC NPs were correspondingly stable in simulated gastric conditions (pH 1.2, 37 °C), due to the offset of size change between pH-responsive expansion and thermo-responsive shrinkage. In simulated intestinal tract (pH 7.0-7.4, 37 °C), DAHBC NPs exhibited burst release of CUR owing to the onefold effect of thermo-responsive shrinkage. DAHBC27 NPs showed the minimum CUR leakage (~10%) in simulated gastric conditions, because a furthest temperature-sensitive shrinkage caused by the lowest LCST offset the expansion in acid environment. DAHBC27 NPs induced ~10-fold increased (P < 0.05) CUR absorption by paracellular transport pathway, compared to the free CUR. Thus, DAHBC NPs stabilized in the gastric environment may be a promising oral drugs delivery system for effective in situ colorectal cancer therapy.

Polypropylene meshes coated with chitosan/polyethylene glycol for the reconstruction of the abdominal wall: an experimental study in rats

ABSTRACT The aim of this study was to characterize the tissue reactions triggered by the polypropylene mesh coated with chitosan and polyethylene glycol film, and if it’s able to prevent the formation of peritoneal adhesions. Defects in the abdominal wall of rats were induced and polypropylene meshes coated with chitosan/polyethylene glycol (CPEG group, n= 12) and uncoated (PP control group, n= 12) were implanted. On the fourth and forty-fifth postoperative day the formation of adhesion and the tissue reaction to the biomaterial was evaluated through histological and histochemical analysis. The area (P= 0.01) and severity (P= 0.002) of the adhesion was significatively less in the CPEG group. On the fourth day the foreign body reaction was less intense in CPEG group (P= 0.018) and the production of collagen fibers was more intense in this group (P= 0.041). The tissue reactions caused by the biomaterials were similar on the 45th day, with the exception of the high organization of collagen fibers in the CPEG group. The CPEG meshes did not fully prevent the formation of adhesions, but minimized the severity of the process. The foreign body reaction promoted by polypropylene meshes coated with CPEG is less intense than that triggered by uncoated polypropylene meshes.

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.

Treatment of dry eye by intracanalicular injection of a thermosensitive chitosan-based hydrogel: evaluation of biosafety and availability

Chitosan has been increasingly considered for the design of implant materials in the field of translational medicine. However, implant properties addressing the complexity of the desired tissue still need to be developed. The focus of this study lies in the evaluation of a thermosensitive chitosan-based hydrogel for intracanalicular injection. Hydroxybutyl chitosan (HBC) solution was prepared, and its cytocompatibility was investigated by the CCK-8 assay using primary human corneal epithelial cells (HCEpiCs). Minimal cytotoxicity was seen in cultures with the HBC-extracting solution at a concentration of 0.2 g ml-1 for up to 72 h incubation. The biocompatibility and effectiveness, based on both a rabbit model and a human pilot study, were evaluated anatomically and functionally. The flow flux significantly decreased after HBC injection, with 76.9% of the flow flux occurring 10 min after HBC injection. Tear secretion significantly improved in the rabbit model. The density of PAS-positive cells gradually increased in the animal model. Various clinical indicators, which include the ocular surface disease index (OSDI) and tear break up time, have been improved greatly. Thermosensitivity promotes greater suitability for HBC intracanalicular injection to obstruct the lacrimal drainage system at body temperature. These results demonstrate that the thermosensitive chitosan-based hydrogel is suitable as a liquid plug for tear flow blockage and thus represents a promising candidate for translational medicine.

Antiadhesion effect of the C17 glycerin ester of isoprenoid-type lipid forming a nonlamellar liquid crystal

Postoperative adhesion is a relevant clinical problem that causes a variety of clinical complications after abdominal surgery. The objective of this study is to develop a liquid-type antiadhesion agent and evaluate its efficacy in preventing tissue adhesion in a rat peritoneal adhesion model. The liquid-type agent was prepared by submicron-sized emulsification of C17 glycerin ester (C17GE), squalene, pluronic F127, ethanol, and water with a high-pressure homogenizer. The primary component was C17GE, which is an amphiphilic lipid of one isoprenoid-type hydrophobic chain and can form two phases of self-assembly nonlamellar liquid crystals. The C17GE agent consisted of nanoparticles with an internal inverted hexagonal phase when evaluated by small-angle X-ray scattering (SAXS) and cryo-transmission electron microscopy (cryo-TEM). Upon contact with the biological tissue, this agent formed a thin membrane with a bioadhesive property. After this agent was applied to a sidewall injury of rats, it showed a percentage average of adhesion significantly less than that obtained with the Seprafilm® antiadhesion membrane in a rat model. Additionally, the retention of the agent prolonged at the applied site in the peritoneal cavity of rats. In conclusion, the C17GE agent is promising as an antiadhesion material. STATEMENT OF SIGNIFICANCE: Postoperative adhesion remains a common adverse effect. Although various materials have been investigated, there are few products commercially available to prevent adhesion. For the sheet-type agent, it is inconvenient to be applied through small laparotomy, especially in laparoscopic surgery. Additionally, the liquid-type agent currently used requires a complicated procedure to spray at the targeted site. Our liquid-type antiadhesion agent can form liquid crystals and act as a thin membrane-like physical barrier between the peritoneum and tissues to prevent adhesion. Indeed, the antiadhesion agent used in our present study significantly prevents adhesion compared with the antiadhesion membrane most used clinically. Moreover, our agent is highly stable by itself and easy to use in laparoscopic surgery, thus leading to a promising new candidate as an antiadhesion material.

Thermoresponsive polysaccharides and their thermoreversible physical hydrogel networks

Thermoresponsive polymers have been used extensively for various applications including food additives, pharmaceutical formulations, therapeutic delivery, cosmetics and environmental remediation, to mention a few. Many thermoresponsive polymers have the ability to form physical hydrogel networks in response to temperature changes, which are particularly useful for emerging biomedical applications, including cell therapies, drug delivery systems, tissue engineering, wound healing and 3D bioprinting. In particular, the use of polysaccharides with thermoresponsive properties has been of interest due to their wide availability, versatile functionality, biodegradability, and in many cases, inherent biocompatibility. Naturally thermoresponsive polysaccharides include agarose, carrageenans and gellan gum, which exhibit upper critical solution temperatures, transitioning from a solution to a gel state upon cooling. Arguably, this limits their use in biomedical applications, particularly for cell encapsulation as they require raised temperatures to maintain a solution state that may be detrimental to living systems. Conversely, significant progress has been made over recent years to develop synthetically modified polysaccharides, which tend to exhibit lower critical solution temperatures, transitioning from a solution to a gel state upon warming. Of particular interest are thermoresponsive polysaccharides with a lower critical solution temperature in between room temperature and physiological temperature, as their solutions can conveniently be manipulated at room temperature before gelling upon warming to physiological temperature, which makes them ideal candidates for many biological applications. Therefore, this review provides an introduction to the different types of thermoresponsive polysaccharides that have been developed, their resulting hydrogels and properties, and the exciting applications that have emerged as a result of these properties.

Layer-by-layer Polyelectrolytes Coating of Alginate Microgels for Sustained Release of Sodium Benzoate and Zosteric Acid

The potential of sustaining release of very small (Mw < 250 g/mol) hydrophilic drugs up to several days from layer-by-layer (LbL) polyelectrolyte coated alginate microgels (Alg-Ms) was investigated. One purpose is to minimize post-surgical adhesions, which develop in 12 h to 3 days after surgery. The LbL polyelectrolyte layer would serve as a diffusion barrier for their release. The LbL polyelectrolyte bilayers were prepared using poly(allylamine) (PAH) and poly(styrene sulfonate) (PSS). Sodium benzoate (NaB, Mw = 144 g/mol) and zosteric acid (ZA, Mw = 244 g/mol), two anti-inflammatory and anti-microbial compounds, were used as model drugs. A higher number of PAH/PSS bilayer lead to a greater sustained release of both drugs, and with 4 bilayers, the release of NaB and ZA was prolonged from 24 h to 72 h and 120 h, respectively. Fitting the data to the Ritger-Peppas' equation showed that as the bilayer number increased, the release constant and/or exponent decreased, indicating the LbL PAH/PSS bilayer effectively reduced the permeability of these two very small hydrophilic drugs. The ability to prolong the release of such small hydrophilic molecules, which has rarely been investigated previously, would find broad applications in fields such as anti-adhesion treatment and antifouling coatings.

Recent Advances in Edible Polymer Based Hydrogels as a Sustainable Alternative to Conventional Polymers

The over increasing demand of eco-friendly materials to counter various problems, such as environmental issues, economics, sustainability, biodegradability, and biocompatibility, open up new fields of research highly focusing on nature-based products. Edible polymer based materials mainly consisting of polysaccharides, proteins, and lipids could be a prospective contender to handle such problems. Hydrogels based on edible polymer offer many valuable properties compared to their synthetic counterparts. Edible polymers can contribute to the reduction of environmental contamination, advance recyclability, provide sustainability, and thereby increase its applicability along with providing environmentally benign products. This review is highly emphasizing on toward the development of hydrogels from edible polymer, their classification, properties, chemical modification, and their potential applications. The application of edible polymer hydrogels covers many areas including the food industry, agricultural applications, drug delivery to tissue engineering in the biomedical field and provide more safe and attractive products in the pharmaceutical, agricultural, and environmental fields, etc.

Thermoresponsive polysaccharide-based composite hydrogel with antibacterial and healing-promoting activities for preventing recurrent adhesion after adhesiolysis

Postoperative adhesions are very common complications after general abdominal surgery. Although adhesiolysis has been proven effective in eliminating the preexisting adhesions, the new trauma caused by surgical lysis can induce recurrent adhesion. The prevention of recurrent adhesion after adhesiolysis is more difficult because the injury is more severe and adhesion mechanism is more complicated compared with the primary adhesion. In this study, a thermoresponsive hydrogel contained galactose modified xyloglucan (mXG) and hydroxybutyl chitosan (HBC) was developed as a barrier device for recurrent adhesion prevention after adhesiolysis due to its injectability and spontaneous gelling behaviors at the body temperature without any chemical reactions or extra driving factors. First, mXG and HBC were synthesized via enzymatic modification and etherification reaction, respectively. Rheological measurements indicated that the mXG/HBC composite system showed excellent thermosensitivity properties, and their gelation temperature and time can be modulated via adjusting the mXG/HBC ratio. Moreover, the mXG/HBC hydrogel exhibited excellent cytocompatibility and hemocompatibility in vitro. Furthermore, the mXG/HBC hydrogel could promote wound healing in the rat skin wound model. Finally, the efficacy of the mXG/HBC composite hydrogel in the prevention of recurrent adhesion was evaluated in a more rigorous rat repeated-injury adhesion model. The results demonstrated that the composite hydrogel could not only effectively prevent recurrent adhesion after adhesiolysis, but also promote wound healing and reduce scare formation. These results suggested that the mXG/HBC composite hydrogel may be a promising candidate as an injectable anti-adhesion system for clinical applications.

STATEMENT OF SIGNIFICANCE

Although adhesiolysis has been proven effective in eliminating the preexisting adhesions, the new trauma caused by surgical lysis can induce recurrent adhesion. So far, most of the existing barrier systems and pharmacological approaches were developed for primary adhesion prevention while few attention has paid on prevention of recurrent adhesion after adhesiolysis. In the present study, we developed a thermoresponsive polysaccharide-based composite hydrogel by simple mixing galactose modified xyloglucan (mXG) and hydroxybutyl chitosan (HBC). The resulting mXG/HBC composite hydrogel not only was easy to handle and highly effective in preventing the recurrent adhesion after adhesiolysis, but also could promote wound healing and reduce scare formation. Our study provide an effective anti-adhesion system for preventing recurrent adhesion after adhesiolysis.