Dual Regulations of Thermosensitive Heparin-Poloxamer Hydrogel Using ε-Polylysine: Bioadhesivity and Controlled KGF Release for Enhancing Wound Healing of Endometrial Injury

A structure-functionality insight into the bioactivity of microbial polysaccharides toward biomedical applications: A review

Microbial polysaccharides (MPs) are biopolymers secreted by microorganisms such as bacteria and fungi during their metabolic processes. Compared to polysaccharides derived from plants and animals, MPs have advantages such as wide sources, high production efficiency, and less susceptibility to natural environmental influences. The most attractive feature of MPs lies in their diverse biological activities, such as antioxidative, anti-tumor, antibacterial, and immunomodulatory activities, which have demonstrated immense potential for applications in functional foods, cosmetics, and biomedicine. These bioactivities are precisely regulated by their sophisticated molecular structure. However, the mechanisms underlying this precise regulation are not yet fully understood and continue to evolve. This article presents a comprehensive review of the most representative species of MPs, including their fermentation and purification processes and their biomedical applications in recent years. In particular, this work presents an in-depth analysis into the structure-activity relationships of MPs across multiple molecular levels. Additionally, this review discusses the challenges and prospects of investigating the structure-activity relationships, providing valuable insights into the broad and high-value utilization of MPs.

Injectable, stable, and biodegradable hydrogel with platelet-rich plasma induced by l-serine and sodium alginate for effective treatment of intrauterine adhesions

The combination of pharmacological and physical barrier therapy is a highly promising strategy for treating intrauterine adhesions (IUAs), but there lacks a suitable scaffold that integrates good injectability, proper mechanical stability and degradability, excellent biocompatibility, and non-toxic, non-rejection therapeutic agents. To address this, a novel injectable, degradable hydrogel composed of poly(ethylene glycol) diacrylate (PEGDA), sodium alginate (SA), and l-serine, and loaded with platelet-rich plasma (PRP) (referred to as PSL-PRP) is developed for treating IUAs. l-Serine induces rapid gelation within 1 min and enhances the mechanical properties of the hydrogel, while degradable SA provides the hydrogel with strength, toughness, and appropriate degradation capabilities. As a result, the hydrogel exhibits an excellent scaffold for sustained release of growth factors in PRP and serves as an effective physical barrier. In vivo testing using a rat model of IUAs demonstrates that in situ injection of the PSL-PRP hydrogel significantly reduces fibrosis and promotes endometrial regeneration, ultimately leading to fertility restoration. The combined advantages make the PSL-PRP hydrogel very promising in IUAs therapy and in preventing adhesions in other internal tissue wounds.

Bioengineering approaches for the endometrial research and application

The endometrium undergoes a series of precise monthly changes under the regulation of dynamic levels of ovarian hormones that are characterized by repeated shedding and subsequent regeneration without scarring. This provides the potential for wound healing during endometrial injuries. Bioengineering materials highlight the faithful replication of constitutive cells and the extracellular matrix that simulates the physical and biomechanical properties of the endometrium to a larger extent. Significant progress has been made in this field, and functional endometrial tissue bioengineering allows an in-depth investigation of regulatory factors for endometrial and myometrial defects in vitro and provides highly therapeutic methods to alleviate obstetric and gynecological complications. However, much remains to be learned about the latest progress in the application of bioengineering technologies to the human endometrium. Here, we summarize the existing developments in biomaterials and bioengineering models for endometrial regeneration and improving the female reproductive potential.

Stimuli-responsive peptide assemblies: Design, self-assembly, modulation, and biomedical applications

Peptide molecules have design flexibility, self-assembly ability, high biocompatibility, good biodegradability, and easy functionalization, which promote their applications as versatile biomaterials for tissue engineering and biomedicine. In addition, the functionalization of self-assembled peptide nanomaterials with other additive components enhances their stimuli-responsive functions, promoting function-specific applications that induced by both internal and external stimulations. In this review, we demonstrate recent advance in the peptide molecular design, self-assembly, functional tailoring, and biomedical applications of peptide-based nanomaterials. The strategies on the design and synthesis of single, dual, and multiple stimuli-responsive peptide-based nanomaterials with various dimensions are analyzed, and the functional regulation of peptide nanomaterials with active components such as metal/metal oxide, DNA/RNA, polysaccharides, photosensitizers, 2D materials, and others are discussed. In addition, the designed peptide-based nanomaterials with temperature-, pH-, ion-, light-, enzyme-, and ROS-responsive abilities for drug delivery, bioimaging, cancer therapy, gene therapy, antibacterial, as well as wound healing and dressing applications are presented and discussed. This comprehensive review provides detailed methodologies and advanced techniques on the synthesis of peptide nanomaterials from molecular biology, materials science, and nanotechnology, which will guide and inspire the molecular level design of peptides with specific and multiple functions for function-specific applications.

Revisited and innovative perspectives of oral ulcer: from biological specificity to local treatment

Mouth ulcers, a highly prevalent ailment affecting the oral mucosa, leading to pain and discomfort, significantly impacting the patient's daily life. The development of innovative approaches for oral ulcer treatment is of great importance. Moreover, a deeper and more comprehensive understanding of mouth ulcers will facilitate the development of innovative therapeutic strategies. The oral environment possesses distinct traits as it serves as the gateway to the digestive and respiratory systems. The permeability of various epithelial layers can influence drug absorption. Moreover, oral mucosal injuries exhibit distinct healing patterns compared to cutaneous lesions, influenced by various inherent and extrinsic factors. Furthermore, the moist and dynamic oral environment, influenced by saliva and daily physiological functions like chewing and speaking, presents additional challenges in local therapy. Also, suitable mucosal adhesion materials are crucial to alleviate pain and promote healing process. To this end, the review comprehensively examines the anatomical and structural aspects of the oral cavity, elucidates the healing mechanisms of oral ulcers, explores the factors contributing to scar-free healing in the oral mucosa, and investigates the application of mucosal adhesive materials as drug delivery systems. This endeavor seeks to offer novel insights and perspectives for the treatment of oral ulcers.

Growth Factors-Loaded Temperature-Sensitive Hydrogel as Biomimetic Mucus Attenuated Murine Ulcerative Colitis via Repairing the Mucosal Barriers

The pathogenesis of ulcerative colitis (UC) is associated with the shedding of the gut mucus. Herein, inspired by the biological functions of mucus, growth factors-loaded in situ hydrogel (PHE-EK) was designed for UC treatment by integrating dihydrocaffeic acid-modified poloxamer as a thermosensitive material with hyaluronic acid (colitis-specific adhesive), epigallocatechin-3-gallate (antibacterial agent), and bioactive factors (KPV tripeptide and epidermal growth factor). PHE-EK presented good thermosensitive properties, as a flowable liquid at room temperature and gelled within 10 s when exposed to body temperature. PHE-EK hydrogel presented good mechanical strength with a strain of 77.8%. Moreover, PHE-EK hydrogel displayed antibacterial activity against Escherichia coli. Importantly, in vitro and in vivo adhesive tests showed that the PHE-EK hydrogel could specifically adhere to the inflamed colon via electrostatic interaction. When PHE-EK as a biomimetic mucus was rectally administrated to colitis rats, it effectively hindered the body weight loss, reduced the disease activity index and improved the colonic shorting. Moreover, the expression of pro-inflammatory cytokines (e.g., IL-1β, IL-6, and TNF-α) at the laminae propria or epitheliums of the colon for colitis rats was substantially inhibited by PHE-EK. Besides, the colonic epitheliums were well rearranged, and the tight junction proteins (Zonula-1 and Claudin-5) between them were greatly upregulated after PHE-EK treatment. Collectively, PHE-EK might be a promising therapy for UC.

Advancements in hydrogel-based drug delivery systems for the treatment of inflammatory bowel disease: a review

Inflammatory bowel disease (IBD) is a chronic disorder that affects millions of individuals worldwide. However, current drug therapies for IBD are plagued by significant side effects, low efficacy, and poor patient compliance. Consequently, there is an urgent need for novel therapeutic approaches to alleviate IBD. Hydrogels, three-dimensional networks of hydrophilic polymers with the ability to swell and retain water, have emerged as promising materials for drug delivery in the treatment of IBD due to their biocompatibility, tunability, and responsiveness to various stimuli. In this review, we summarize recent advancements in hydrogel-based drug delivery systems for the treatment of IBD. We first identify three pathophysiological alterations that need to be addressed in the current treatment of IBD: damage to the intestinal mucosal barrier, dysbiosis of intestinal flora, and activation of inflammatory signaling pathways leading to disequilibrium within the intestines. Subsequently, we discuss in depth the processes required to prepare hydrogel drug delivery systems, from the selection of hydrogel materials, types of drugs to be loaded, methods of drug loading and drug release mechanisms to key points in the preparation of hydrogel drug delivery systems. Additionally, we highlight the progress and impact of the hydrogel-based drug delivery system in IBD treatment through regulation of physical barrier immune responses, promotion of mucosal repair, and improvement of gut microbiota. In conclusion, we analyze the challenges of hydrogel-based drug delivery systems in clinical applications for IBD treatment, and propose potential solutions from our perspective.

Guanidinylated bioactive chitosan-based injectable hydrogels with pro-angiogenic and mechanical properties for accelerated wound closure

Wound healing is a complex process involving the concerted action of many genes and signaling pathways, with angiogenesis being crucial for expediting wound closure. Dressings that possess pro-angiogenic properties are increasingly recognized as attractive candidates for wound care. Drawing inspiration from the active closure of wounds in embryos, we have developed a thermo-responsive hydrogel with mechanoactive properties, combining vascular regeneration and skin wound contraction to accelerate healing. The significant improvement in vascular reconstruction is attributed to the synergistic effect of arginine and deferoxamine (DFO) released from the hydrogels. Additionally, the contraction force of the hydrogel actively promotes skin closure in wounds. Remarkably, groups treated with hydroxybutyl chitosan methacrylate combined with arginine (HBC_m_Arg/DFO) exhibited increased vascularization, and greater wound maturity, leading to enhanced healing. These results highlight the synergistic impact of pro-angiogenic and mechanical properties of the HBC_m_Arg/DFO hydrogel in accelerating wound healing in rats.

Cyclical endometrial repair and regeneration: Molecular mechanisms, diseases, and therapeutic interventions

The endometrium is a unique human tissue with an extraordinary ability to undergo a hormone-regulated cycle encompassing shedding, bleeding, scarless repair, and regeneration throughout the female reproductive cycle. The cyclical repair and regeneration of the endometrium manifest as changes in endometrial epithelialization, glandular regeneration, and vascularization. The mechanisms encompass inflammation, coagulation, and fibrinolytic system balance. However, specific conditions such as endometriosis or TCRA treatment can disrupt the process of cyclical endometrial repair and regeneration. There is uncertainty about traditional clinical treatments' efficacy and side effects, and finding new therapeutic interventions is essential. Researchers have made substantial progress in the perspective of regenerative medicine toward maintaining cyclical endometrial repair and regeneration in recent years. Such progress encompasses the integration of biomaterials, tissue-engineered scaffolds, stem cell therapies, and 3D printing. This review analyzes the mechanisms, diseases, and interventions associated with cyclical endometrial repair and regeneration. The review discusses the advantages and disadvantages of the regenerative interventions currently employed in clinical practice. Additionally, it highlights the significant advantages of regenerative medicine in this domain. Finally, we review stem cells and biologics among the available interventions in regenerative medicine, providing insights into future therapeutic strategies.

Microneedle-based cell delivery and cell sampling for biomedical applications

Cell-based therapeutics are novel therapeutic strategies that can potentially treat many presently incurable diseases through novel mechanisms of action. Cell therapies may benefit from the ease, safety, and efficacy of administering therapeutic cells. Despite considerable recent technological and biological advances, several barriers remain to the clinical translation and commercialization of cell-based therapies, including low patient compliance, personal handling inconvenience, poor biosafety, and limited biocompatibility. Microneedles (MNs) are emerging as a promising biomedical device option for improved cell delivery with little invasion, pain-free administration, and simplicity of disposal. MNs have shown considerable promise in treating a wide range of diseases and present the potential to improve cell-based therapies. In this review, we first summarized the latest advances in the various types of MNs developed for cell delivery and cell sampling. Emphasis was given to the design and fabrication of various types of MNs based on their structures and materials. Then we focus on the recent biomedical applications status of MNs-mediated cell delivery and sampling, including tissue repair (wound healing, heart repair, and endothelial repair), cancer treatment, diabetes therapy, cell sampling, and other applications. Finally, the current status of clinical application, potential perspectives, and the challenges for clinical translation are also highlighted.

Engineering self-healing adhesive hydrogels with antioxidant properties for intrauterine adhesion prevention

Intrauterine adhesion (IUA) is the fibrosis within the uterine cavity. It is the second most common cause of female infertility, significantly affecting women's physical and mental health. Current treatment strategies fail to provide a satisfactory therapeutic outcome for IUA patients, leaving an enormous challenge for reproductive science. A self-healing adhesive hydrogel with antioxidant properties will be highly helpful in IUA prevention. In this work, we prepare a series of self-healing hydrogels (P10G15, P10G20, and P10G25) with antioxidant and adhesive properties. Those hydrogels exhibit good self-healing properties and can adapt themselves to different structures. They possess good injectability and fit the shape of the human uterus. Moreover, the hydrogels exhibit good tissue adhesiveness, which is desirable for stable retention and therapeutic efficacy. The in vitro experiments using P10G20 show that the adhesive effectively scavenges ABTS+, DPPH, and hydroxyl radicals, rescuing cells from oxidative stress. In addition, P10G20 offers good hemocompatibility and in vitro and in vivo biocompatibility. Furthermore, P10G20 lowers down the in vivo oxidative stress and prevents IUA with less fibrotic tissue and better endometrial regeneration in the animal model. It can effectively downregulate fibrosis-related transforming growth factor beta 1 (TGF-β1) and vascular endothelial growth factor (VEGF). Altogether, these adhesives may be a good alternative for the clinical treatment of intrauterine adhesion.

Treatment strategies for intrauterine adhesion: focus on the exosomes and hydrogels

Intrauterine adhesion (IUA), also referred to as Asherman Syndrome (AS), results from uterine trauma in both pregnant and nonpregnant women. The IUA damages the endometrial bottom layer, causing partial or complete occlusion of the uterine cavity. This leads to irregular menstruation, infertility, or repeated abortions. Transcervical adhesion electroreception (TCRA) is frequently used to treat IUA, which greatly lowers the prevalence of adhesions and increases pregnancy rates. Although surgery aims to disentangle the adhesive tissue, it can exacerbate the development of IUA when the degree of adhesion is severer. Therefore, it is critical to develop innovative therapeutic approaches for the prevention of IUA. Endometrial fibrosis is the essence of IUA, and studies have found that the use of different types of mesenchymal stem cells (MSCs) can reduce the risk of endometrial fibrosis and increase the possibility of pregnancy. Recent research has suggested that exosomes derived from MSCs can overcome the limitations of MSCs, such as immunogenicity and tumorigenicity risks, thereby providing new directions for IUA treatment. Moreover, the hydrogel drug delivery system can significantly ameliorate the recurrence rate of adhesions and the intrauterine pregnancy rate of patients, and its potential mechanism in the treatment of IUA has also been studied. It has been shown that the combination of two or more therapeutic schemes has broader application prospects; therefore, this article reviews the pathophysiology of IUA and current treatment strategies, focusing on exosomes combined with hydrogels in the treatment of IUA. Although the use of exosomes and hydrogels has certain challenges in treating IUA, they still provide new promising directions in this field.

Recent advances of Pluronic-based copolymers functionalization in biomedical applications

The design of polymeric biocompatible nanomaterials for biological and medical applications has received special attention in recent years. Among different polymers, the triblock type copolymers (EO)_x(PO)_y(EO)_x or Pluronics® stand out due its favorable characteristics such as biocompatibility, low tissue adhesion, thermosensitivity, and structural capacity to produce different types of macro and nanostructures, e.g. micelles, vesicles, nanocapsules, nanospheres, and hydrogels. However, Pluronic itself is not the "magic bullet" and its functionalization via chemical synthesis following biologically oriented design rules is usually required aiming to improve its properties. Therefore, this paper presents some of the main publications on new methodologies for synthetic modifications and applications of Pluronic-based nanoconstructs in the biomedical field in the last 15 years. In general, the polymer modifications aim to improve physical-chemical properties related to the micellization process or physical entrapment of drug cargo, responsive stimuli, active targeting, thermosensitivity, gelling ability, and hydrogel formation. Among these applications, it can be highlighted the treatment of malignant neoplasms, infectious diseases, wound healing, cellular regeneration, and tissue engineering. Functionalized Pluronic has also been used for various purposes, including medical diagnosis, medical imaging, and even miniaturization, such as the creation of lab-on-a-chip devices. In this context, this review discusses the main scientific contributions to the designing, optimization, and improvement of covalently functionalized Pluronics aiming at new strategies focused on the multiple areas of the biomedical field.

In situ photo-crosslinking silk fibroin based hydrogel accelerates diabetic wound healing through antibacterial and antioxidant

Bacterial infection and excessive reactive oxygen species (ROS) in diabetic wounds lead to a prolonged inflammatory phase, and injuries are highly susceptible to developing into chronic wounds. Improving the poor microenvironment is vital to achieving effective diabetic wound healing. In this work, methacrylated silk fibroin (SFMA) was combined with ε-polylysine (EPL) and manganese dioxide nanoparticles (BMNPs) to form an SF@(EPL-BM) hydrogel with in situ forming, antibacterial and antioxidant properties. EPL imparted high antibacterial activity (>96 %) to the hydrogel. BMNPs and EPL showed good scavenging activity against a variety of free radicals. SF@(EPL-BM) hydrogel had low cytotoxicity and could alleviate H₂O₂-induced oxidative stress in L929 cells. In diabetic wounds infected with Staphylococcus aureus (S. aureus), the SF@(EPL-BM) hydrogel exhibited better antibacterial properties and reduced wound ROS levels more significantly than that of the control in vivo. In this process, the pro-inflammatory factor TNF-α was down-regulated, and the vascularization marker CD31 was up-regulated. H&E and Masson staining showed a rapid transition from the inflammatory to the proliferative phase of the wounds, with significant new tissue and collagen deposition. These results confirm that this multifunctional hydrogel dressing holds well potential for chronic wound healing.

A Decellularized Uterine Endometrial Scaffold Enhances Regeneration of the Endometrium in Rats

Partial or whole regeneration of the uterine endometrium using extracellular matrix (ECM)-based scaffolds is a therapeutic strategy for uterine infertility due to functional and/or structural endometrial defects. Here, we examined whether the entire endometrium can be regenerated circumferentially using an acellular ECM scaffold (decellularized endometrial scaffold, DES) prepared from rat endometrium. We placed a silicone tube alone to prevent adhesions or a DES loaded with a silicone tube into a recipient uterus in which the endometrium had been surgically removed circumferentially. Histological and immunofluorescent analyses of the uteri one month after tube placement revealed more abundant regenerated endometrial stroma in the uterine horns treated with tube-loaded DES compared to those treated with a tube alone. Luminal and glandular epithelia, however, were not fully recapitulated. These results suggest that DES can enhance the regeneration of endometrial stroma but additional intervention(s) are needed to induce epithelization. Furthermore, the prevention of adhesions alone allowed the endometrial stroma to regenerate circumferentially even without a DES, but to a lesser degree than that with a DES. The use of a DES together with the prevention of adhesions may be beneficial for efficient endometrial regeneration in the uterus that is largely deficient of endometrium.

Stimuli-Responsive Polysaccharide Hydrogels and Their Composites for Wound Healing Applications

There is a growing concern about wound care, since traditional dressings such as bandages and sutures can no longer meet existing needs. To address the demanding requirements, naturally occurring polymers have been extensively exploited for use in modern wound management. Polysaccharides, being the most abundant biopolymers, have some distinct characteristics, including biocompatibility and biodegradability, which render them ideal candidates for wound healing applications. Combining them with inorganic and organic moieties can produce effective multifunctional composites with the desired mechanical properties, high wound healing efficiencies and excellent antibacterial behavior. Recent research endeavors focus on the development of stimuli-responsive polysaccharide composites for biomedical applications. Polysaccharide composites, being sensitive to the local environment, such as changes of the solution temperature, pH, etc., can sense and react to the wound conditions, thus promoting an effective interaction with the wound. This review highlights the recent advances in stimuli-responsive polysaccharide hydrogels and their composites for use in wound healing applications. The synthetic approaches, physical, chemical, and biochemical properties as well as their function in wound healing will be discussed.

Smart thermosensitive poloxamer hydrogels loaded with Nr-CWs for the treatment of diabetic wounds

The treatment of diabetic wound is a focus issue. At present, the Nocardia rubra cell wall skeleton (Nr-CWS) has been proved proven to promote angiogenesis and wound repair. Unfortunately, the high-glucose diabetic wound environment makes many drugs unable to be released effectively, and soon be removed. Smart thermosensitive poloxamer hydrogel (TH) is an ideal and adjustable drug delivery platform compatible with most living tissues. Here, a multifunctional composite thermosensitive hydrogel was developed. A mixture of poloxamers 407 and 188 as the gel matrix, and then it was physically mixed with Nr-CWS. The delivery vehicle not only controlled its release stably, preventing degradation in vitro, but also showed good affinity in vitro. In vivo, compared with thermosensitive poloxamer hydrogel alone or the direct use of Nr-CWS, the thermosensitive poloxamer hydrogel loaded with Nr-CWS promoted the proliferation of vascular endothelial cells effectively, resulting in increased expression of derma-related structural proteins and enhanced angiogenesis and wound healing. This study indicated that the angiogenesis and skin regeneration brought by Nr-CWS hydrogel are related to the activation of phosphatidylinositol 3 kinase and protein kinase B, Janus kinase/signal transducer and activator of transcription, and mitogen-activated protein kinase kinase/extracellular signal-regulated kinase signaling pathways.

Research progress of stem cell therapy for endometrial injury

Endometrial damage is an important factor leading to infertility and traditional conventional treatments have limited efficacy. As an emerging technology in recent years, stem cell therapy has provided new hope for the treatment of this disease. By comparing the advantages of stem cells from different sources, it is believed that menstrual blood endometrial stem cells have a good application prospect as a new source of stem cells. However, the clinical utility of stem cells is still limited by issues such as colonization rates, long-term efficacy, tumor formation, and storage and transportation. This paper summarizes the mechanism by which stem cells repair endometrial damage and clarifies the material basis of their effects from four aspects: replacement of damaged sites, paracrine effects, interaction with growth factors, and other new targets. According to the pathological characteristics and treatment requirements of intrauterine adhesion (IUA), the research work to solve the above problems from the aspects of functional bioscaffold preparation and multi-functional platform construction is also summarized. From the perspective of scaffold materials and component functions, this review will provide a reference for comprehensively optimizing the clinical application of stem cells.

Nanomaterials based on thermosensitive polymer in biomedical field

The progress of nanotechnology enables us to make use of the special properties of materials on the nanoscale and open up many new fields of biomedical research. Among them, thermosensitive nanomaterials stand out in many biomedical fields because of their “intelligent” behavior in response to temperature changes. However, this article mainly reviews the research progress of thermosensitive nanomaterials, which are popular in biomedical applications in recent years. Here, we simply classify the thermally responsive nanomaterials according to the types of polymers, focusing on the mechanisms of action and their advantages and potential. Finally, we deeply investigate the applications of thermosensitive nanomaterials in drug delivery, tissue engineering, sensing analysis, cell culture, 3D printing, and other fields and probe the current challenges and future development prospects of thermosensitive nanomaterials.

Biomaterial strategies for the application of reproductive tissue engineering

Human reproductive organs are of vital importance to the life of an individual and the reproduction of human populations. So far, traditional methods have a limited effect in recovering the function and fertility of reproductive organs and tissues. Thus, aim to replace and facilitate the regrowth of damaged or diseased tissue, various biomaterials are developed to offer hope to overcome these difficulties and help gain further research progress in reproductive tissue engineering. In this review, we focus on the biomaterials and their four main applications in reproductive tissue engineering: in vitro generation and culture of reproductive cells; development of reproductive organoids and models; in vivo transplantation of reproductive cells or tissues; and regeneration of reproductive tissue. In reproductive tissue engineering, designing biomaterials for different applications with different mechanical properties, structure, function, and microenvironment is challenging and important, and deserves more attention.

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Various biomaterials have been developed and used in reproductive tissue engineering.

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3D culture systems can lead to better cell-cell interactions for in vitro production of reproductive cells.

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Reproductive organoids and models are formed by biomaterials to simulate the environment of natural reproductive organs.

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Biomaterials should promote vascular regeneration and resist inflammation for in-situ reproductive tissue regeneration.

Recent Developments in Biomaterial-Based Hydrogel as the Delivery System for Repairing Endometrial Injury

Endometrial injury caused by intrauterine surgery often leads to pathophysiological changes in the intrauterine environment, resulting in infertility in women of childbearing age. However, clinical treatment strategies, especially for moderate to severe injuries, often fail to provide satisfactory therapeutic effects and pregnancy outcomes. With the development of reproductive medicine and materials engineering, researchers have developed bioactive hydrogel materials, which can be used as a physical anti-adhesion barrier alone or as functional delivery systems for intrauterine injury treatment by loading stem cells or various active substances. Studies have demonstrated that the biomaterial-based hydrogel delivery system can provide sufficient mechanical support and improve the intrauterine microenvironment, enhance the delivery efficiency of therapeutic agents, prolong intrauterine retention time, and perform efficiently targeted repair compared with ordinary drug therapy or stem cell therapy. It shows the promising application prospects of the hydrogel delivery system in reproductive medicine. Herein, we review the recent advances in endometrial repair methods, focusing on the current application status of biomaterial-based hydrogel delivery systems in intrauterine injury repair, including preparation principles, therapeutic efficacy, repair mechanisms, and current limitations and development perspectives.

A methacrylated hyaluronic acid network reinforced Pluronic F-127 gel for treatment of bacterial keratitis

In this study, we developed a novel in situ thermoresponsive gel by introducing crosslinked methacrylated hyaluronic acid (HA-MA) networks into Pluronic F-127 (PF-127) gel (HP gel) to achieve levofloxacin (LFX) delivery in bacterial keratitis treatment. The interactions between PF-127 and HA-MA networks were studied by scanning electron microscopy, rheology, dynamic light scattering, differential scanning calorimetry, and small angle X-ray scattering. The results showed that the HP gel exhibited a higher critical gelling temperature and lower viscosity than the PF-127 gel (P gel), and could form a uniform thin layer on the ocular surface. Moreover, the drug release profile and gel dissolution rate revealed that the HA-MA network could retard the diffusion and dissolution of drug molecules and prolong the drug release time, which corresponded to an enhanced antibacterial ability of the HP-LFX gel. Furthermore, the HP gel exhibited low cytotoxicity to human corneal epithelial cells (HCECs). Finally, an in vivo pharmacodynamic study was conducted with rabbit keratitis models. An improved treatment efficacy was observed after application of the HP-LFX gels. This study highlights the potential of HP gels in ophthalmic drug delivery.

A KPV-binding double-network hydrogel restores gut mucosal barrier in an inflamed colon

Ulcerative colitis (UC) usually occurs in the superficial mucosa of the colorectum. Here, a double-network hydrogel (PMSP) was constructed from maleimided γ-polyglutamic acid and thiolated γ-polyglutamic acid through crosslinking of thiol-maleimide and self-oxidized thiols. PMSP with a negative charge specifically adhered to the inflamed mucosa with positively charged proteins rather than to the healthy mucosa. PMSP exhibited good mechanical strength with storage modulus (G') of 17.6 Pa and a linear viscoelastic region (LVR) of 107.2% strain. Moreover, PMSP showed a stronger bio-adhesive force toward the inflamed tissue-mimicking substrate than toward its healthy counterpart. In vivo imaging confirmed that PMSP specifically adhered to the inflamed colonic mucosa of rats with TNBS-induced UC. KPV (Lys-Pro-Val) as a model drug was easily captured by PMSP through electrostatic interactions, thus retaining its bioactivity for a longer time under high temperature conditions. Moreover, the alleviating effect of KPV on rats with TNBS-induced colitis was significantly improved by PMSP after intracolonic administration. The epithelial barrier of the colon also effectively recovered following PMSP-KPV treatment. PMSP-KPV also modulated the gut flora, markedly augmenting the abundance of beneficial microorganisms in gut homeostasis. The mechanism by which PMSP-KPV induces a therapeutic effect may be associated with the inhibition of oxidative stress. Conclusively, the PMSP hydrogel seems to be a promising rectal delivery system for the therapy of UC. STATEMENT OF SIGNIFICANCE: Ulcerative colitis (UC) is a chronic and relapsing disease of the gastrointestinal tract. A key therapeutic approach to treat UC is to repair the mucosal barriers. Here, a double-network hydrogel (PMSP) was constructed from maleimided and thiolated γ-polyglutamic acid through crosslinking of thiol-maleimide and self-oxidized thiols. The negatively charged PMSP specifically adhered to the inflamed colon rather than its healthy counterpart and was retained for a longer time. KPV as a model drug was easily captured by PMSP, which provided better stability to KPV when exposed to high temperature of 50 °C. The epithelial mucosal barrier of the colon was effectively recovered by the rectal administration of PMSP-KPV to rats with TNBS-induced UC. Moreover, PMSP-KPV modulated the gut flora of colitic rats, markedly augmenting the abundance of beneficial microorganisms. Conclusively, PMSP seems to be a promising rectal delivery system for UC therapy.

OUP accepted manuscript

BACKGROUND

To provide the optimal milieu for implantation and fetal development, the female reproductive system must orchestrate uterine dynamics with the appropriate hormones produced by the ovaries. Mature oocytes may be fertilized in the fallopian tubes, and the resulting zygote is transported toward the uterus, where it can implant and continue developing. The cervix acts as a physical barrier to protect the fetus throughout pregnancy, and the vagina acts as a birth canal (involving uterine and cervix mechanisms) and facilitates copulation. Fertility can be compromised by pathologies that affect any of these organs or processes, and therefore, being able to accurately model them or restore their function is of paramount importance in applied and translational research. However, innate differences in human and animal model reproductive tracts, and the static nature of 2D cell/tissue culture techniques, necessitate continued research and development of dynamic and more complex in vitro platforms, ex vivo approaches and in vivo therapies to study and support reproductive biology. To meet this need, bioengineering is propelling the research on female reproduction into a new dimension through a wide range of potential applications and preclinical models, and the burgeoning number and variety of studies makes for a rapidly changing state of the field.

OBJECTIVE AND RATIONALE

This review aims to summarize the mounting evidence on bioengineering strategies, platforms and therapies currently available and under development in the context of female reproductive medicine, in order to further understand female reproductive biology and provide new options for fertility restoration. Specifically, techniques used in, or for, the uterus (endometrium and myometrium), ovary, fallopian tubes, cervix and vagina will be discussed.

SEARCH METHODS

A systematic search of full-text articles available in PubMed and Embase databases was conducted to identify relevant studies published between January 2000 and September 2021. The search terms included: bioengineering, reproduction, artificial, biomaterial, microfluidic, bioprinting, organoid, hydrogel, scaffold, uterus, endometrium, ovary, fallopian tubes, oviduct, cervix, vagina, endometriosis, adenomyosis, uterine fibroids, chlamydia, Asherman’s syndrome, intrauterine adhesions, uterine polyps, polycystic ovary syndrome and primary ovarian insufficiency. Additional studies were identified by manually searching the references of the selected articles and of complementary reviews. Eligibility criteria included original, rigorous and accessible peer-reviewed work, published in English, on female reproductive bioengineering techniques in preclinical (in vitro/in vivo/ex vivo) and/or clinical testing phases.

OUTCOMES

Out of the 10 390 records identified, 312 studies were included for systematic review. Owing to inconsistencies in the study measurements and designs, the findings were assessed qualitatively rather than by meta-analysis. Hydrogels and scaffolds were commonly applied in various bioengineering-related studies of the female reproductive tract. Emerging technologies, such as organoids and bioprinting, offered personalized diagnoses and alternative treatment options, respectively. Promising microfluidic systems combining various bioengineering approaches have also shown translational value.

WIDER IMPLICATIONS

The complexity of the molecular, endocrine and tissue-level interactions regulating female reproduction present challenges for bioengineering approaches to replace female reproductive organs. However, interdisciplinary work is providing valuable insight into the physicochemical properties necessary for reproductive biological processes to occur. Defining the landscape of reproductive bioengineering technologies currently available and under development for women can provide alternative models for toxicology/drug testing, ex vivo fertility options, clinical therapies and a basis for future organ regeneration studies.

Recent trends in therapeutic strategies for repairing endometrial tissue in intrauterine adhesion

Intrauterine adhesion (IUA) is a common gynaecological disease that develops from infection or trauma. IUA disease may seriously affect the physical and mental health of women of childbearing age, which may lead to symptoms such as hypomenorrhea or infertility. Presently, hysteroscopic transcervical resection of adhesion (TCRA) is the principal therapy for IUAs, although its function in preventing the recurrence of adhesion and preserving fertility is limited. Pharmaceuticals such as hormones and vasoactive agents and the placement of nondegradable stents are the most common postoperative adjuvant therapy methods. However, the repair of injured endometrium is relatively restricted due to the different anatomical structures of the endometrium. Recently, the treatment outcome of IUAs has improved with the advancement of hysteroscopic techniques. In particular, the application of bioactive scaffolds combined with tissue engineering technology has proven to have high therapeutic potential or endometrial repair in IUA treatment. Herein, this review has summarized past therapeutic strategies, including postoperative adjuvant therapy, cell or therapeutic molecular delivery therapy methods and bioactive scaffold-based tissue engineering methods. Therefore, this review presented the recent therapeutic strategies for repairing endometrium treatment and pointed out the issues of clinical concern to provide alternative methods for the management of IUAs.

Polyelectrolyte Gels: Fundamentals, Fabrication and Applications

Polyelectrolyte gels are an important class of polymer gels and a versatile platform with charged polymer networks with ionisable groups. They have drawn significant recent attention as a class of smart material and have demonstrated potential for a variety of applications. This review begins with the fundamentals of polyelectrolyte gels, which encompass various classifications (i.e., origin, charge, shape) and crucial aspects (ionic conductivity and stimuli responsiveness). It further centralises recent developments of polyelectrolyte gels, emphasising their synthesis, structure-property relationships and responsive properties. Sequentially, this review demonstrates how polyelectrolyte gels' flourishing properties create attractiveness to a range of applications including tissue engineering, drug delivery, actuators and bioelectronics. Finally, the review outlines the indisputable appeal, further improvements and emerging trends in polyelectrolyte gels.

Women-specific routes of administration for drugs: A critical overview

The woman's body presents a number of unique anatomical features that can constitute valuable routes for the administration of drugs, either for local or systemic action. These are associated with genitalia (vaginal, endocervical, intrauterine, intrafallopian and intraovarian routes), changes occurring during pregnancy (extra-amniotic, intra-amniotic and intraplacental routes) and the female breast (breast intraductal route). While the vaginal administration of drug products is common, other routes have limited clinical application and are fairly unknown even for scientists involved in drug delivery science. Understanding the possibilities and limitations of women-specific routes is of key importance for the development of new preventative, diagnostic and therapeutic strategies that will ultimately contribute to the advancement of women's health. This article provides an overview on women-specific routes for the administration of drugs, focusing on aspects such as biological features pertaining to drug delivery, relevance in current clinical practice, available drug dosage forms/delivery systems and administration techniques, as well as recent trends in the field.

Functional Hydrogels as Wound Dressing to Enhance Wound Healing

Hydrogels, due to their excellent biochemical and mechnical property, have shown attractive advantages in the field of wound dressings. However, a comprehensive review of the functional hydrogel as a wound dressing is still lacking. This work first summarizes the skin wound healing process and relates evaluation parameters and then reviews the advanced functions of hydrogel dressings such as antimicrobial property, adhesion and hemostasis, anti-inflammatory and anti-oxidation, substance delivery, self-healing, stimulus response, conductivity, and the recently emerged wound monitoring feature, and the strategies adopted to achieve these functions are all classified and discussed. Furthermore, applications of hydrogel wound dressing for the treatment of different types of wounds such as incisional wound and the excisional wound are summarized. Chronic wounds are also mentioned, and the focus of attention on infected wounds, burn wounds, and diabetic wounds is discussed. Finally, the future directions of hydrogel wound dressings for wound healing are further proposed.

Controlled release of KGF-2 for regulation of wound healing by KGF-2 complexed with "lotus seedpod surface-like" porous microspheres

Keratinocyte growth factor-2 (KGF-2) can regulate the proliferation and differentiation of keratinocyte, which plays a remarkable role in maintaining normal tissue structure and promoting wound healing. As an effective strategy, KGF-2 solution is widely used in the treatment of wounds in clinical applications. However, KGF-2 in solution cannot achieve sustained release, which results in drug loss and unnecessary waste. Polysaccharide hemostasis microspheres (PHMs) are an ideal drug loading platform due to their special "lotus seedpod surface-like" morphology and structure. Herein, to realize the controllable release of KGF-2, PHMs loaded with KGF-2 (KGF-2@PHMs) were prepared. It was found that the bioavailability of KGF-2 was improved greatly. Most importantly, KGF-2@PHMs can reduce inflammation and accelerate the wound healing process due to the controlled release of KGF-2. KGF-2@PHMs might be a potential alternative strategy for wound healing in future clinical applications.

Hydrogel, a novel therapeutic and delivery strategy, in the treatment of intrauterine adhesions

Intrauterine adhesions (IUAs) are caused by damage to the underlying lining of the endometrium. They' re related to disorder of endometrial repair. In recent years, hydrogels with controllable biological activity have been widely used for treating IUAs. They encapsulate estrogen, cytokines, cells, or exosomes, forming a delivery system to release therapeutic components for the treatment of IUAs. In addition, the hydrogel acting as a barrier can be degraded in the body automatically, reducing the risk of infection caused by secondary surgeries. In this review, we summarize the recent progress of hydrogels and their application in IUAs as both a novel alternative therapeutic and an artificial delivery strategy.

Recent Progress on Polysaccharide-Based Hydrogels for Controlled Delivery of Therapeutic Biomolecules

A plethora of applications using polysaccharides have been developed in recent years due to their availability as well as their frequent nontoxicity and biodegradability. These polymers are usually obtained from renewable sources or are byproducts of industrial processes, thus, their use is collaborative in waste management and shows promise for an enhanced sustainable circular economy. Regarding the development of novel delivery systems for biotherapeutics, the potential of polysaccharides is attractive for the previously mentioned properties and also for the possibility of chemical modification of their structures, their ability to form matrixes of diverse architectures and mechanical properties, as well as for their ability to maintain bioactivity following incorporation of the biomolecules into the matrix. Biotherapeutics, such as proteins, growth factors, gene vectors, enzymes, hormones, DNA/RNA, and antibodies are currently in use as major therapeutics in a wide range of pathologies. In the present review, we summarize recent progress in the development of polysaccharide-based hydrogels of diverse nature, alone or in combination with other polymers or drug delivery systems, which have been implemented in the delivery of biotherapeutics in the pharmaceutical and biomedical fields.

Polysaccharide-Based Materials Created by Physical Processes: From Preparation to Biomedical Applications

Polysaccharide-based materials created by physical processes have received considerable attention for biomedical applications. These structures are often made by associating charged polyelectrolytes in aqueous solutions, avoiding toxic chemistries (crosslinking agents). We review the principal polysaccharides (glycosaminoglycans, marine polysaccharides, and derivatives) containing ionizable groups in their structures and cellulose (neutral polysaccharide). Physical materials with high stability in aqueous media can be developed depending on the selected strategy. We review strategies, including coacervation, ionotropic gelation, electrospinning, layer-by-layer coating, gelation of polymer blends, solvent evaporation, and freezing-thawing methods, that create polysaccharide-based assemblies via in situ (one-step) methods for biomedical applications. We focus on materials used for growth factor (GFs) delivery, scaffolds, antimicrobial coatings, and wound dressings.

Bioengineering of the Uterus

Impairment of uterine structure and function causes infertility, pregnancy loss, and perinatal complications in humans. Some types of uterine impairments such as Asherman’s syndrome, also known as uterine synechiae, can be treated medically and surgically in a standard clinical setting, but absolute defects of uterine function or structure cannot be cured by conventional approaches. To overcome such hurdles, partial or whole regeneration and reconstruction of the uterus have recently emerged as new therapeutic strategies. Transplantation of the whole uterus into patients with uterine agenesis results in the successful birth of children. However, it remains an experimental treatment with numerous difficulties such as the need for continuous and long-term use of immunosuppressive drugs until a live birth is achieved. Thus, the generation of the uterus by tissue engineering technologies has become an alternative but indispensable therapeutic strategy to treat patients without a functional or well-structured uterus. For the past 20 years, the bioengineering of the uterus has been studied intensively in animal models, providing the basis for clinical applications. A variety of templates and scaffolds made from natural biomaterials, synthetic materials, or decellularized matrices have been characterized to efficiently generate the uterus in a manner similar to the bioengineering of other organs and tissues. The goal of this review is to provide a comprehensive overview and perspectives of uterine bioengineering focusing on the type, preparation, and characteristics of the currently available scaffolds.

Characterization and antibacterial properties of epsilon-poly- l-lysine grafted multi-functional cellulose beads

In recent years, harmful microorganisms in water pose great harm to ecological environment and human health. To solve this problem, epsilon-poly-l-lysine (EPL) grafted cellulose beads were prepared via 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO) mediated oxidation and carbodiimide mediated cross-linking reaction. Hydroxyl groups on C6 of cellulose were oxidized to carboxyl groups by TEMPO and grafting reaction was achieved between newly formed carboxyl groups of cellulose and amino of EPL. The beads were characterized by FTIR, SEM, XRD and TGA. The crystalline form of cellulose transformed from cellulose I to cellulose II after being dissolved and regenerated. The grafted cellulose beads showed good antibacterial activities against Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus and Alicyclobacillus acidoterrestris with 10 h. The beads could be biodegraded in soil after 28 days. It is expected that the bio-based composite beads could have potential applications in water purification and food treatment fields.

Recent developments in bio-scaffold materials as delivery strategies for therapeutics for endometrium regeneration

Intrauterine adhesions (IUAs) refer to the repair disorder after endometrial injury and may lead to uterine infertility, recurrent miscarriage, abnormal menstrual bleeding, and other obstetric complications. It is a pressing public health issue among women of childbearing age. Presently, there are limited clinical treatments for IUA, and there is no sufficient evidence that these treatment modalities can effectively promote regeneration after severe endometrial injury or improve pregnancy outcome. The inhibitory pathological micro-environment is the main factor hindering the repair of endometrial damaged tissues. To address this, tissue engineering and regenerative medicine have been achieving promising developments. Particularly, biomaterials have been used to load stem cells or therapeutic factors or construct an in situ delivery system as a treatment strategy for endometrial injury repair. This article comprehensively discusses the characteristics of various bio-scaffold materials and their application as stem cell or therapeutic factor delivery systems constructed for uterine tissue regeneration.

Temperature-sensitive hydrogel for rectal perfusion improved the therapeutic effect of Kangfuxin liquid on DSS-induced ulcerative colitis mice: The inflammation alleviation and the colonic mucosal barriers repair

Kangfuxin liquid (KFX) is a Chinese medicine extracted from Periplaneta americana dried worms, which presented the bioactive functions of anti-inflammation and promoting the gastrointestinal mucosal barriers repair. But the low availability of KFX exposed to the distal colon affects its therapeutic effect on ulcerative colitis. Herein, an in situ hydrogel containing KFX was designed by using temperature-sensitive poloxamer 407 (P-407) as material for rectal administration. Three KFX-P formulations with different P407 concentrations (17%, 20% and 25%) were designed and screened by detecting the gelation time, gelation temperature and mechanical strength of hydrogel. P407 in these formulations was able to be completely dissolved in KFX at 4 ℃ and then was in situ gelled at 37 ℃ to form a semisolid hydrogel. Moreover, the gelation time, the gelation temperature and the mechanical strength of KFX-P hydrogel are highly dependent on P407 concentration. With P407 concentration increasing, both the gelation time and gelation temperature of KFX-P accordingly decreased and the gelation temperature range becomes narrowed; while the mechanical strength increased. KFX-P-20% displayed the moderate gelation temperature (28-30 ℃), the short gelation time (26 s) and the moderate mechanical strength (G' = 4.2 × 10³ Pa), which was chosen for animal study. Thereafter, ulcerative colitis mice model (UC) was established by dextran sulfate sodium (DSS) and the therapeutic effect of KFX-P on UC was evaluated by inflammation symptoms relief, colon length, colonic MPO level and colonography. After rectal administration of KFX or KFX-P, the symptoms including diarrhea and hematochezia (DAI scores), weight loss and spleen swelling were significantly hindered. Meanwhile, the colonic MPO level in these groups was significantly decreased in comparison with PBS treatment. But the therapeutic effect of KFX-P was better than KFX. Besides, the morphology and mucosal barrier of colon were evaluated by HE staining, ZO-1 and claudin-5 staining. The mucosa epithelium layer, crypt, muscle layer mucosa and submucosa were also well repaired after KFX-P treatment. The strong fluorescence of ZO-1 and claudin-5 were uniformly distributed along the whole epithelial mucosa after KFX-P treatment, indicating the effective repairing of the colonic mucosal barrier. Collectively, the temperature-sensitive KFX-P for rectal delivery could effectively promote the repair of the colon mucosal barrier and inhibit the colonic inflammation in DSS-induced mice, which may be a potential strategy for UC treatment.

Poloxamer: A versatile tri-block copolymer for biomedical applications

Poloxamers, also called Pluronic, belong to a unique class of synthetic tri-block copolymers containing central hydrophobic chains of poly(propylene oxide) sandwiched between two hydrophilic chains of poly(ethylene oxide). Some chemical characteristics of poloxamers such as temperature-dependent self-assembly and thermo-reversible behavior along with biocompatibility and physiochemical properties make poloxamer-based biomaterials promising candidates for biomedical application such as tissue engineering and drug delivery. The microstructure, bioactivity, and mechanical properties of poloxamers can be tailored to mimic the behavior of various types of tissues. Moreover, their amphiphilic nature and the potential to self-assemble into the micelles make them promising drug carriers with the ability to improve the drug availability to make cancer cells more vulnerable to drugs. Poloxamers are also used for the modification of hydrophobic tissue-engineered constructs. This article collects the recent advances in design and application of poloxamer-based biomaterials in tissue engineering, drug/gene delivery, theranostic devices, and bioinks for 3D printing. STATEMENT OF SIGNIFICANCE: Poloxamers, also called Pluronic, belong to a unique class of synthetic tri-block copolymers containing central hydrophobic chains of poly(propylene oxide) sandwiched between two hydrophilic chains of poly(ethylene oxide). The microstructure, bioactivity, and mechanical properties of poloxamers can be tailored to mimic the behavior of various types of tissues. Moreover, their amphiphilic nature and the potential to self-assemble into the micelles make them promising drug carriers with the ability to improve the drug availability to make cancer cells more vulnerable to drugs. However, no reports have systematically reviewed the critical role of poloxamer for biomedical applications. Research on poloxamers is growing today opening new scenarios that expand the potential of these biomaterials from "traditional" treatments to a new era of tissue engineering. To the best of our knowledge, this is the first review article in which such issue is systematically reviewed and critically discussed in the light of the existing literature.

Aloe/poloxamer hydrogel as an injectable β-estradiol delivery scaffold with multi-therapeutic effects to promote endometrial regeneration for intrauterine adhesion treatment

Intrauterine adhesion (IUA) is characterized by endometrial stromal replaced with fibrous tissue during the trauma or operation induced injury. Current clinic IUA management mainly involves surgical removal of the connective tissues and physical separation and often results in reoccurrence. It is of clinic interest to directly address the issue via facilitating the endometrial repair and thereby inhibiting the formation of re-adhesion. To this end, we designed a nanocomposite aloe/poloxamer hydrogel for β-estradiol (E2) intrauterine delivery to exert multi-therapeutic effects and promote endometrial regeneration for IUA treatment. Nanoparticulate decellularized uterus (uECMNPs) was prepared to encapsulate E2 (E2@uECMNPs), which improved the solubility and prolonged cargo release. Then, E2@uECMNPs were further embedded into the thermosensitive aloe-poloxamer hydrogel (E2@uECMNPs/AP). Multiple components from E2@uECMNPs/AP system could collectively promote proliferation and inhibit apoptosis of endometrial stromal cells. E2@uECMNPs/AP significantly increased morphological recovery and decreased uterine fibrosis rate compared with IUA rats in other groups in vivo. Additionally, the levels of Ki67, cytokeratin, and estrogen receptor β were all up-regulated, along with the decreased expression of TGF-β1 and TNF-α in the uterus from rats receiving E2@uECMNPs/AP therapy. Taken together, in situ administration of E2@uECMNPs/AP hydrogel could effectively promote endometrial regeneration and prevent the re-adhesion.

Effects of early second-look hysteroscopy combined with intrauterine balloon dilatation on reproductive outcomes for women with intrauterine adhesions

OBJECTIVE

To investigate the effect of early second-look office hysteroscopy combined with intrauterine balloon dilatation on prognosis and pregnancy rate for women with intrauterine adhesions.

METHODS

A retrospective analysis of 156 women diagnosed with intrauterine adhesions by hysteroscopy at Shenyang Women's and Children's Hospital, China, from April 2017 to January 2019. The study women underwent intrauterine balloon dilatation 10 days after transcervical resection of adhesion (TCRA) and hysteroscopy 20 days after TCRA (n=81). The control women underwent hysteroscopy 3 months after TCRA (n=75). Estrogen and aspirin were routinely administered postoperatively to all women. Data, including American Fertility Society (AFS) scores assessed by hysteroscopy, endometrial thickness measured by ultrasound, and menstruation and pregnancy outcomes assessed by interview, were compared between the two groups.

RESULTS

The degree of intrauterine adhesions, menstrual status, and endometrial thickness were improved in both groups after TCRA. Greater improvement in AFS score, menstruation, and endometrial thickness was observed in the study group than in the control group. After follow-up, more women in the study group achieved pregnancy (48.1% vs 30.7%, P<0.05).

CONCLUSION

Early second-look of hysteroscopy combined with intrauterine balloon dilatation after hysteroscopic TRCA might improve the prognosis and postoperative pregnancy rate for women with intrauterine adhesions.

Therapeutic options and drug delivery strategies for the prevention of intrauterine adhesions

Intrauterine adhesions (IUAs) are bands of fibrous tissue that form in the endometrial cavity and associated with the increased risk of abnormal menstruation, recurrent pregnancy loss, secondary infertility, and pregnancy complications. Physical barriers, including intrauterine device and hydrogel, were clinical available to prevent the post-operational IUAs. But physically separation of the injured endometrium relies on the own limited healing power and often ends with recurrence. In recent years, the mechanisms driving IUAs treatment has validated the application of hormones, and further stem cell therapy has also led to the development of novel therapeutic agents with promising efficacy in pre-clinical and initial clinical studies. Still, it is challenging to delivery the therpaeutic factors to the injured uterus. Herein, in this review, we discuss the traditional intervention methods for the prevention of IUAs, as well as novel therapeutics and delivery strategies that will most likely change the treatment paradigms for better clinical outcomes. The combination strategy that using physical barriers as the delivery carriers for therapeutics might provide new alternatives for the prevention of IUAs.

pH-Responsive Polypeptide-Based Smart Nano-Carriers for Theranostic Applications

Smart nano-carriers have attained great significance in the biomedical field due to their versatile and interesting designs with different functionalities. The initial stages of the development of nanocarriers mainly focused on the guest loading efficiency, biocompatibility of the host and the circulation time. Later the requirements of less side effects with more efficacy arose by attributing targetability and stimuli-responsive characteristics to nano-carriers along with their bio- compatibility. Researchers are utilizing many stimuli-responsive polymers for the better release of the guest molecules at the targeted sites. Among these, pH-triggered release achieves increasing importance because of the pH variation in different organ and cancer cells of acidic pH. This specific feature is utilized to release the guest molecules more precisely in the targeted site by designing polymers having specific functionality with the pH dependent morphology change characteristics. In this review, we mainly concert on the pH-responsive polypeptides and some interesting nano-carrier designs for the effective theranostic applications. Also, emphasis is made on pharmaceutical application of the different nano-carriers with respect to the organ, tissue and cellular level pH environment.

Establishment and comparison of different intrauterine adhesion modelling procedures in rats

Intrauterine adhesion (IUA) is caused by endometrial damage and leads to the formation of scar fibrosis and repair disorders. We compared four different rat IUA modelling procedures in order to establish a stable animal model suitable for investigating IUA. Twenty female Sprague--Dawley rats were randomly divided into four groups. IUA was induced on one side of each rat uterus by ethanol instillation, heat stripping, mechanical injury or mechanical injury with infection (dual-injury); the other side of the uterus was left intact as a control. After 8 days the rats were sacrificed, their uteri were examined for histomorphology and expression of endometrial markers was checked using immunohistochemistry. All four IUA modelling procedures resulted in visual pathophysiological changes in the rat uterus, including stenosis, congestion and loss of elasticity. Endometrial thinning, shrinkage of glands and formation of fibrotic hyperplasia were also observed. All four procedures resulted in the downregulation of cytokeratin 18 and vimentin expression compared with control tissues, as well as the upregulation of collagen I expression. After mechanical injury and dual-injury the expression of interleukin 6 was significantly increased. Overall, our results suggest that ethanol instillation is the most stable IUA modelling procedure. Mechanical injury reliably yielded inflammatory indicators.