Adipocyte-targeted delivery of rosiglitazone with localized photothermal therapy for the treatment of diet-induced obesity in mice

Obesity represents a growing public health concern and is closely associated with metabolic complications such as diabetes and fatty liver disease. Anti-obesity medications currently available have limited efficacy in weight loss and are often accompanied by adverse effects. This study proposes a localized photothermal therapy (PTT) combined with adipocyte-targeted delivery of rosiglitazone (RSG) to address obesity. Specifically, cationic albumin nanoparticles (cNPs) were synthesized to deliver RSG precisely to white adipocytes, stimulating the browning process. An IR780-loaded thermosensitive hydrogel was injected and allowed to gel in situ to afford a subcutaneous reservoir that enables localized PTT and controlled release of RSG cNPs. Notably, cNPs significantly enhanced the internalization efficiency in adipocytes in vitro and prolonged the therapeutic retention in the adipose tissue in vivo. Co-administration of RSG cNPs and PTT substantially reduced fat content, induced browning in white adipose tissue in diet-induced obese mice, and mitigated complications such as insulin resistance, fatty liver, and hyperlipidemia. The increased expression of uncoupling protein 1 contributes to enhancing energy expenditure and facilitating adipose metabolism, thereby effectively combating obesity. This therapeutic approach integrates localized PTT with adipocyte-targeted delivery to combat the global obesity epidemic thus offering a promising solution with reduced systemic toxicity and enhanced efficacy. STATEMENT OF SIGNIFICANCE: Cationic albumin nanoparticles are capable of efficient internalization in adipocytes, which may enhance drug targeting to adipose tissue. The combination of rosiglitazone-loaded cationic albumin nanoparticles and local hyperthermia effectively reduces lipid accumulation in adipocytes and induces an upregulated expression of uncoupling protein 1. The combination therapy effectively inhibits fat accumulation, induces adipocyte browning, and regulates systemic metabolism in diet-induced obese mice.

Systemic platelet inhibition with localized chemotherapy by an injectable ROS-scavenging gel against postsurgical breast cancer recurrence and metastasis

Early solid tumors benefit from surgical resection, but residual stubborn microtumors, pro-inflammatory microenvironment and activated platelets at the postoperative wound site are prone to recurrence and metastasis, resulting in poor prognosis. Here, we developed a dual-pronged strategy consisting of (i) in-situ forming ROS-scavenging gels loaded with anticancer drugs at the postoperative wound site to improve the tumor microenvironment and inhibit the recurrence of residual microtumors after orthotopic surgery, and (ii) systemic administration of clopidegrol via albumin nanoparticles for inhibiting activated platelets in the circulation thus inhibiting tumor remote migration. In a mouse model of postoperative recurrence and metastasis of orthotopic 4T1 breast cancer, the dual-pronged strategy greatly inhibited postoperative orthotopic tumor recurrence and reduced lung metastasis. This work provides an effective strategy for the postoperative intervention and treatment of solid tumors to inhibit postoperative tumor recurrence and metastasis, which has the potential to improve the prognosis and survival of patients with postoperative solid tumors. STATEMENT OF SIGNIFICANCE: Early-stage solid tumors benefit from surgical resection. However, the presence of residual microtumors, pro-inflammatory tumor microenvironment, and activated platelets at the postoperative wound site lead to recurrence and metastasis, ultimately resulting in poor prognosis. Here, we have devised a dual-pronged approach that includes (i) in-situ forming ROS-scavenging gels loaded with anticancer drugs (TM@Gel) at the wound site after surgery to enhance the tumor microenvironment (TME) and hinder the reappearance of residual microtumors, and (ii) systemic administration of clopidegrol through albumin nanoparticles (HHP) for inhibiting activated platelets in the circulation thus impeding tumor distant migration. This work provides a viable option for postoperative intervention and treatment of solid tumors to suppress postoperative tumor recurrence and metastasis.

Injectable microcapillary network hydrogels engineered by liquid-liquid phase separation for stem cell transplantation

Injectable hydrogels are promising carriers for cell delivery in regenerative medicine. However, injectable hydrogels composed of crosslinked polymer networks are often non-microporous and prevent biological communication with host tissues through signals, nutrients, oxygen, and cells, thereby limiting graft survival and tissue integration. Here we report injectable hydrogels with liquid-liquid phase separation-induced microcapillary networks (μCN) as stem cell-delivering scaffolds. The molecular modification of gelatin with hydrogen bonding moieties induced liquid-liquid phase separation when mixed with unmodified gelatin to form μCN structures in the hydrogels. Through spatiotemporally controlled covalent crosslinking and dissolution processes, porous μCN structures were formed in the hydrogels, which can enhance mass transport and cellular activity. The encapsulation of cells with injectable μCN hydrogels improved cellular spreading, migration, and proliferation. Transplantation of mesenchymal stem cells with injectable μCN hydrogels enhanced graft survival and recovered hindlimb ischemia by enhancing material-tissue communication with biological signals and cells through μCN. This facile approach may serve as an advanced scaffold for improving stem cell transplantation therapies in regenerative medicine.

Long-acting anti-inflammatory injectable DEX-Gel with sustained release and self-healing properties regulates TH1/TH2 immune balance for minimally invasive treatment of allergic rhinitis

BACKGROUND

Allergic rhinitis (AR) is a prevalent immune-related allergic disease, and corticosteroid nasal sprays serve as the primary treatment for this patient population. However, their short duration of efficacy and frequent administration pose challenges, leading to drug wastage and potential adverse effects. To overcome these limitations, we devised a novel approach to formulate DEX-Gel by incorporating dexamethasone (DEX) into a blend of Pluronic F127, stearic acid (SA), and polyethylene glycol 400 (PEG400) to achieve sustained-release treatment for AR.

RESULTS

Following endoscopic injection into the nasal mucosa of AR rats, DEX-Gel exhibited sustained release over a 14-day period. In vivo trials employing various assays, such as flow cytometry (FC), demonstrated that DEX-Gel not only effectively managed allergic symptoms but also significantly downregulated helper T-cells (TH) 2 and TH2-type inflammatory cytokines (e.g., interleukins 4, 5, and 13). Additionally, the TH1/TH2 cell ratio was increased.

CONCLUSION

This innovative long-acting anti-inflammatory sustained-release therapy addresses the TH1/TH2 immune imbalance, offering a promising and valuable approach for the treatment of AR and other inflammatory nasal diseases.

An injectable gel based on photo-cross-linkable hyaluronic acid and mesoporous bioactive glass nanoparticles for periodontitis treatment

Guided bone regeneration (GBR) is an effective strategy to promote periodontal tissue repair. The current study aimed to develop an injectable gel for GBR, composed of photo-cross-linkable hyaluronic acid and mesoporous bioactive glass nanoparticles (MBGNs) loaded with antibacterial minocycline hydrochloride (MNCl). Hyaluronic acid modified with methacrylic anhydride (MHA) that could be cross-linked under UV irradiation was first synthesized. Dynamic rheological evaluation of MHA under UV was carried out to determine its in-situ gelling feasibility and stability. Morphological and mechanical characterization was performed to determine the optimal concentration of MHA gels. Sol-gel derived MBGNs loaded with MNCl were further incorporated into MHA gels to obtain the injectable drug-loaded MBGN-MNCl/MHA gels. In vitro antibacterial, anti-inflammatory and osteogenic effects of this gel were evaluated. It was shown that the MHA gel obtained from 3 % MHA under UV treatment of 30s exhibited a suitable porous structure with a compressive strength of 100 kPa. MBGNs with particle size of ∼120 nm and mesopores were confirmed by TEM and SEM. MBGNs had a loading capacity of ∼120 mg/g for MNCl, exhibiting a sustained release behavior. The MBGN-MNCl/MHA gel was shown to effectively inhibit the proliferation of Streptococcus mutans and the expression of pro-inflammatory factors IL-6 and TNF-α by macrophages. It could on the other hand significantly promote the expression of osteogenic-related genes ALP, Runx2, OPN, and osterix of MC3T3-E1 cells. In conclusion, the current design using photo-crosslinkable MHA gel embedded with MNCl loaded MBGNs can serve as a promising injectable formulation for GBR treatment of irregular periodontal defects.

Dual-radiolabelling of an injectable hyaluronan-tyramine-bisphosphonate hybrid gel for in vitro and in vivo tracking

Hyaluronan (HA) have been widely used as the ideal biomaterials. It is important to understand their degradation and distribution for better optimization. From a new aspect of using radiotracers, we designed the HA-tyramine-bisphosphonate derivative for dual-labelling with two radionuclides (^99mTc and ¹³¹I) simultaneously for in vitro and in vivo tracking. This dual-radiolabelled HA derivative can still be non-covalently crosslinked by hydroxyapatites to form injectable gel. The excellent properties of the gel, such as robust, biodegradable, and self-healing capacity were maintained. We firstly proved the possibility to distinguish different radionuclides in the degraded gel using the high-resolution gamma-ray spectrometry. The radiolabelled gel showed lower toxicity than pure hydroxyapatites against various cell lines, while the in vivo results proved that the ^99mTc/¹³¹I-labelling of the gel was safe and stable enough for imaging and quantitatively tracking. The present method can also be applied for the development of dual-radiolabelled gels from other polysaccharides.

A Thixotropic, Cell-Infiltrative Nanocellulose Hydrogel That Promotes in Vivo Tissue Remodeling

Injectable gels have been used in minimally invasive surgery for tissue regeneration and treatment of inflammatory diseases. However, polymeric hydrogels often fail in cell infiltration, because of the presence of dense, cross-linked molecular networks and a lack of bioactivity, which causes delayed tissue remodeling. Here, we report a thixotropic, cell-infiltrative hydrogel of biofunctionalized nanocellulose that topologically enhances cell infiltration and biochemically upregulates cellular activity for the promotion of tissue remodeling. Biodegradable, sulfonated nanocellulose forms a nanofibrous hydrogel, mimicking cellular microenvironments through cross-linking between nanocellulose and gelatin. Resulting nanocellulose hydrogels showed thixotropy, allowing for single syringe injection. Nanofiber-based hydrogels possess high molecular permeability, which is due to nanoporous structures. Sulfonate groups on nanocellulose increase protein adsorption and induce cellular extension in vitro. Highly sulfonated nanocellulose hydrogels enhanced cell infiltration and vascularization upon implantation into rats. Macrophage polarization to M2 was observed in nanocellulose hydrogels, which may be involved in tissue remodeling. Injectable, biofunctionalized nanocellulose gels have enormous potential as artificial biomatrices to heal inflammatory diseases through manipulation of the immune system and promotion of tissue remodeling.

Cervical Augmentation with an Injectable Silk-Based Gel: Biocompatibility in a Rat Model of Pregnancy

The aim of this study was to study the biocompatibility of an injectable silk gel in the cervix in a rat model of pregnancy. The rationale is to study an injectable gel as an alternate treatment for cervical insufficiency. We further aimed to perform cervical injections via a vaginal route to mimic the clinical procedure of a cervical cerclage. We performed an in vivo study in pregnant female Sprague Dawley rats. Cervical procedures were performed using a customized speculum under general anesthesia. Injections were performed on gestational day 16. The responses to silk gel injections were compared to polyethylene terephthalate suture and saline controls on gestational day 19 and postpartum. The inflammatory response was evaluated by histology, PCR for inflammatory gene expression, and ELISA for protein levels of proinflammatory mediators. Silk gel injections were performed on 13 animals. All animals tolerated the procedure. Silk gel occupied 5% of the stroma after injection. Injected silk gel caused neither preterm birth nor prolonged pregnancy and had no effect on the kits. When comparing inflammatory responses, expression of inflammatory genes and proinflammatory proteins in the silk gel group was intermediate between saline (lowest) and cerclage suture (highest). Injectable silk gel was more inflammatory compared to saline injections but less inflammatory compared to the suture material used for cervical cerclage. This study is an important step toward development of an alternative treatment for cervical insufficiency.

The protective effects of acupoint gel embedding on rats with myocardial ischemia-reperfusion injury

AIMS

Prevention and treatment of myocardial ischemia-reperfusion (I/R) injury has for many years been a hot topic in treating ischemic heart disease. As one of the most well-known methods of complementary and alternative medicine, acupuncture has attracted increasing interest in preventing myocardial I/R injury due to its remarkable effectiveness and minimal side effect. However, traditional acupuncture approaches are limited by cumbersome execution, high labor costs and inevitable pain caused by frequent stimulation. Therefore, in this work, we aimed to develop a novel acupoint gel embedding approach and investigated its role in protecting against myocardial I/R injury in rats.

MAIN METHODS

Gels were embedded at bilateral Neiguan (PC6) points of rats and their protective effects against myocardial I/R injury evaluated in terms of changes in histomorphology, myocardial enzymology, antioxidant capacity, anti-inflammatory response, and anti-apoptosis of cells.

KEY FINDINGS

We found that the approach of acupoint gel embedding could significantly reduce myocardial infarcted size, repair pathological changes, mitigate oxidative stress damage and inflammatory response, as well as inhibit apoptosis of cardiomyocytes. Such cardioprotective effects were found to be associated with Notch-1/Jagged-1 signaling pathway.

SIGNIFICANCE

The proposed approach of acupoint gel embedding has advantages in continuous acupoint stimulation, dosing controls, and no side effects in the course of treatment, as well as in reducing the pain caused by frequent acupuncture. It can form an alternative therapy to not only protect against myocardial I/R injury but also hold great potential in treating other diseases in the future.

Subconjunctival injectable dendrimer-dexamethasone gel for the treatment of corneal inflammation

Corneal inflammation is often encountered as a key pathological event in many corneal diseases. Current treatments involve topical corticosteroids which require frequent instillations due to rapid tear turnover, causing side-effects such as corneal toxicity and elevated intraocular pressure (IOP). Hence, new interventions that can reduce side effects, dosing frequency, and increase patient compliance can be highly beneficial. In this study, we explore a subconjunctival injectable gel based on G4-PAMAM dendrimer and hyaluronic acid, cross-linked using thiol-ene click chemistry, incorporated with dendrimer dexamethasone (D-Dex) conjugates as a potential strategy for sustained delivery and enhanced bioavailability of corticosteroids. The efficacy of the injectable gel formulation was evaluated in a rat mild alkali burn model. Fluorescently-labelled dendrimers (D-Cy5) incorporated in the gel release D-Cy5 in vivo. The released D-Cy5 selectively targets and localizes within corneal macrophages in inflamed rat cornea but not in healthy controls. This pathology dependent biodistribution was exploited for drug delivery, by incorporating D-Dex in the injectable gel. The attenuation of corneal inflammation by D-Dex gels was assessed using various clinical and biochemical parameters over a 2-week period. Subconjunctival D-Dex gel treatment resulted in favorable clinically-relevant outcomes with reduced central corneal thickness and improved corneal clarity compared to free-Dex and placebo gel controls. The extent of corneal neovascularization was significantly reduced in the D-Dex group. These findings suggest that D-Dex attenuates corneal inflammation more effectively than free-Dex by attenuating macrophage infiltration and pro-inflammatory cytokines expression. A significant elevation in IOP was not observed in the D-Dex group but was observed in the free-Dex group. This novel injectable D-Dex gel may be a potential drug delivery platform for the treatment of many inflammatory ocular surface disorders such as dry eye, auto-immune keratitis and post-surgical complications where frequent steroid administration is required.

One-pot synthesis of injectable methylcellulose hydrogel containing calcium phosphate nanoparticles

A thermo-sensitive hydrogel based on calcium phosphate nanoparticles was prepared using a novel one-pot method in which added precursor salts induced a salt-out effect in the methylcellulose (MC) solution. The calcium phosphate nanoparticles were synthesized in situ from precursor ions (Ca²⁺ and HPO₄^2-) in the hydrogel, and residual ions (HPO₄^2- and Cl^-) in the formation of the nanoparticles decreased the gelation temperature of the MC solution. This one-pot synthesis was an effective way to streamline the previous multi-step process and to easily prepare a thermo-sensitive hydrogel containing bioactive nanoparticles. The thermo-sensitive properties of different concentrations of MC hydrogels were characterized by a rheometer and infrared (IR) spectroscopy. The gelation behavior of MC according to the addition of various salts was monitored by rheometer. With respect to a selected concentration and precursor, the structure of the MC hydrogel containing calcium phosphate nanoparticles was analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and IR.

Preparation and evaluation of a phospholipid-based injectable gel for the long term delivery of leuprolide acetaterrh

A phospholipid-based injectable gel was developed for the sustained delivery of leuprolide acetate (LA). The gel system was prepared using biocompatible materials (SPME), including soya phosphatidyl choline (SPC), medium chain triglyceride (MCT) and ethanol. The system displayed a sol state with low viscosity in vitro and underwent in situ gelation in vivo after subcutaneous injection. An in vitro release study was performed using a dialysis setup with different release media containing different percentages of ethanol. The stability of LA in the SPME system was investigated under different temperatures and in the presence of various antioxidants. In vivo studies in male rats were performed to elucidate the pharmacokinetic profiles and pharmacodynamic efficacy. A sustained release of LA for 28 days was observed without obvious initial burst in vivo. The pharmacodynamic study showed that once-a-month injection of LA-loaded SPME (SPME-LA) led to comparable suppression effects on the serum testosterone level as observed in LA solution except for the onset time. These findings demonstrate excellent potential for this novel SPME system as a sustained release delivery system for LA.