A chitosan/beta-glycerophosphate thermo-sensitive gel for the delivery of ellagic acid for the treatment of brain cancer

Hyaluronic Acid/Ellagic Acid as Materials for Potential Medical Application

The aim of this work was to develop and characterize a thin films composed of hyaluronic acid/ellagic acid for potential medical application. Its principal novelty, distinct from the prior literature in terms of hyaluronic acid films supplemented with phenolic acids, resides in the predominant incorporation of ellagic acid-a distinguished compound-as the primary constituent of the films. Herein, ellagic acid was dissolved in two different solvents, i.e., acetic acid (AcOH) or sodium hydroxide (NaOH), and the surface properties of the resultant films were assessed using atomic force microscopy and contact angle measurements. Additionally, various physicochemical parameters were evaluated including moisture content, antioxidant activity, and release of ellagic acid in phosphate buffered saline. Furthermore, the evaluation of films' biocompatibility was conducted using human epidermal keratinocytes, dermal fibroblasts, and human amelanotic melanoma cells (A375 and G361), and the antimicrobial activity was elucidated accordingly against Staphylococcus aureus ATCC 6538 and Pseudomonas aeruginosa ATCC 15442. Our results showed that the films exhibited prominent antibacterial properties particularly against Staphylococcus aureus, with the 80HA/20EA/AcOH film indicating the strong biocidal activity against this strain leading to a significant reduction in viable cells. Comparatively, the 50HA/50EA/AcOH film also displayed biocidal activity against Staphylococcus aureus. This experimental approach could be a promising technique for future applications in regenerative dermatology or novel strategies in terms of bioengineering.

Research on triamcinolone-loaded thermosensitive chitosan hydrogels for preventing esophageal stricture induced by endoscopic submucosal dissection

Early-stage esophageal cancer is primarily treated by endoscopic submucosal dissection (ESD). However, extensive mucosal dissection creates a significant risk of postoperative esophageal stricture. Clinically, postoperative stricture can be prevented by glucocorticoids; however, there are drawbacks to both systemic and local administration of glucocorticoids, and improving drug administration methods is crucial. In this study, we developed a chitosan-based thermosensitive hydrogel for triamcinolone (TA) delivery. Our results indicated that the hydrogel remains liquid at low temperatures and can be injected into the esophageal wound site through an endoscopic biopsy channel. Upon reaching body temperature, the hydrogel undergoes spontaneous gelation and firmly adheres to the wound surface. The liquid phase enables convenient and precise delivery, while the gel phase achieves remarkable adhesion, tensile strength, and resistance to degradation. Moreover, the hydrogel exhibited an extended release duration of >10 days when loaded with a 10 mg dose. In vitro studies revealed that the hydrogel suppresses the proliferation and fibrogenesis of human scar fibroblasts (HKF). In a rat skin dermal defect model, the hydrogel attenuated keloid formation during the healing process. Consequently, the chitosan-based thermosensitive hydrogel developed in this study for triamcinolone delivery may be an effective tool for preventing post-ESD esophageal stricture.

Application of Thermoresponsive Smart Polymers based in situ Gel as a Novel Carrier for Tumor Targeting

The temperature-triggered in situ gelling system has been revolutionized by introducing an intelligent polymeric system. Temperature-triggered polymer solutions are initially in a sol state and then undergo a phase transition to form a gel at body temperature due to various parameters like pH, temperature, and so on. These smart polymers offer a number of advantages, including ease of administration, long duration of release of the drug, low administration frequency with good patient compliance, and targeted drug delivery with fewer adverse effects. Polymers such as poly(N-isopropylacrylamide) (PNIPAAm), polyethylene glycol (PEG), poly (N, N'-diethyl acrylamide), and polyoxypropylene (PPO) have been briefly discussed. In addition to various novel Drug Delivery Systems (DDS), the smart temperature-triggered polymeric system has various applications in cancer therapy and many other disease conditions. This review focuses on the principals involved in situ gelling systems using various temperature-triggered polymers for chemotherapeutic purposes, using smart DDS, and their advanced application in cancer therapy, as well as available marketed formulations and recent advances in these thermoresponsive sol-gel transforming systems.

Xanthine oxidase inhibitory kinetics and mechanism of ellagic acid: In vitro, in silico and in vivo studies

Ellagic acid (EA), which is widely distributed in many foods, has been found to possess inhibitory activity against xanthine oxidase (XO). However, there is ongoing debate about the difference in XO inhibitory activity between EA and allopurinol. Additionally, the inhibitory kinetics and mechanism of EA on XO are still unclear. Herein, the authors systematically studied the inhibitory effects of EA on XO. The authors' findings showed that EA is a reversible inhibitor with mixed-type inhibition, and its inhibitory activity is weaker than allopurinol. Fluorescence quenching experiments suggested that the generation of EA-XO complex was exothermic and spontaneous. In silico analysis further confirmed that EA entered the XO catalytic centre. Furthermore, the authors verified the anti-hyperuricemia effect of EA in vivo. This study elucidates the inhibition kinetics and mechanism of EA on XO, and lays a theoretical foundation for the further development of drugs and functional foods containing EA for the treatment of hyperuricemia.

Immunological evaluation of a recombinant vaccine delivered with an analogous hyaluronic acid chitosan nanoparticle-hydrogel against Toxoplasma gondii in mice

BACKGROUND

Toxoplasma gondii (T. gondii) is not only a threat to the public health but it also poses adverse impacts on the livestock industry. This study aimed to develop a recombinant vaccine composed of T. gondii microneme protein 6 (TgMIC6) and T. gondii rhoptry protein 18 (TgROP18).The vaccine was delivered with a novel vector, named analogous hyaluronic acid chitosan nanoparticle-hydrogel (AHACNP-HG) and its immune protection was evaluated.

METHODS

The recombinant MIC6 and ROP18 proteins were obtained by affinity chromatography and loaded onto AHACNP-HG by magnetic stirring. The characterizations of AHACNP-HG were investigated, including its structure, rheological property, nanoparticle size and zeta potential, its ability to release protein in vitro and toxicology in vivo. The immunological and anti-infection effects of AHACNP-HG/rMIC6/rROP18 were examined in the mice model.

RESULTS

AHACNP-HG presented a characteristic of composite system and possessed biosecurity with excellent protein control-release property. AHACNP-HG/rMIC6/rROP18 vaccine enhanced a mixed Th1/Th2 cellular immune response accompanied by an increased level of the cytokines, IFN-γ and IL-10. It also provoked a stronger humoral immune response. Additionally, after challenge with T. gondii tachyzoite, AHACNP-HG/rMIC6/rROP18 inoculation prolonged the survival time of mice.

CONCLUSION

Our data indicated that mixed rMIC6 and rROP18 induced strong immune response and played a certain protective role in controlling T. gondii infection, and the novel adjuvant AHACNP-HG improved modestly some immunogenicity properties in mouse model, which indicated that it can be used as a novel delivery system in vaccine development.

Loco-regional treatment with temozolomide-loaded thermogels prevents glioblastoma recurrences in orthotopic human xenograft models

Glioblastoma multiforme (GBM) is the most aggressive primary tumor of the central nervous system and the diagnosis is often dismal. GBM pharmacological treatment is strongly limited by its intracranial location beyond the blood-brain barrier (BBB). While Temozolomide (TMZ) exhibits the best clinical performance, still less than 20% crosses the BBB, therefore requiring administration of very high doses with resulting unnecessary systemic side effects. Here, we aimed at designing new negative temperature-responsive gel formulations able to locally release TMZ beyond the BBB. The biocompatibility of a chitosan-β-glycerophosphate-based thermogel (THG)-containing mesoporous SiO₂ nanoparticles (THG@SiO₂) or polycaprolactone microparticles (THG@PCL) was ascertained in vitro and in vivo by cell counting and histological examination. Next, we loaded TMZ into such matrices (THG@SiO₂-TMZ and THG@PCL-TMZ) and tested their therapeutic potential both in vitro and in vivo, in a glioblastoma resection and recurrence mouse model based on orthotopic growth of human cancer cells. The two newly designed anticancer formulations, consisting in TMZ-silica (SiO₂@TMZ) dispersed in the thermogel matrix (THG@SiO₂-TMZ) and TMZ, spray-dried on PLC and incorporated into the thermogel (THG@PCL-TMZ), induced cell death in vitro. When applied intracranially to a resected U87-MG-Red-FLuc human GBM model, THG@SiO₂-TMZ and THG@PCL-TMZ caused a significant reduction in the growth of tumor recurrences, when compared to untreated controls. THG@SiO₂-TMZ and THG@PCL-TMZ are therefore new promising gel-based local therapy candidates for the treatment of GBM.

In situ gelling drug delivery systems for topical drug delivery

In situ gelling formulations are drug delivery systems which typically exist in a liquid form at room temperature and change into gel state after application to the body in response to various stimuli such as changes in temperature, pH and ionic composition. Their biomedical application can further be improved by incorporating drug nanoparticles into in situ gelling systems in order to prolong drug release, reduce dosing frequency and improve therapeutic outcomes of patients, developing highly functional but challenging dosage forms. The composition of in situ gelling formulations influence factors relating to performance such as their syringeability, rheology, drug release profile and drug bioavailability at target sites, amongst other factors. The inclusion of mucoadhesive polymeric constituents into in situ gelling formulations has also been explored to ensure that the therapeutic agents are retained at target site for extended period of time. This review article will discuss traditional techniques (water bath-based vial inversion and viscometry) as well as advanced methodology (rheometry, differential scanning calorimetry, Small Angle Neutron Scattering, Small Angle X-ray Scattering, etc.) for evaluating in situ gel forming systems for topical drug delivery. The clinical properties of in situ gelling systems that have been studied for potential biomedical applications over the last ten years will be reviewed to highlight current knowledge in the performance of these systems. Formulation issues that have slowed the translation of some promising drug formulations from the research laboratory to the clinic will also be detailed.

Tuning the Mechanical Properties of Multiarm RAFT-Based Block Copolyelectrolyte Hydrogels via Ionic Cross-Linking for 3D Cell Cultures

Hydrogels that serve as native extracellular matrix (ECM) mimics are typically naturally derived hydrogels that are physically cross-linked via ionic interactions. This means rapid gelation of synthetic polymers, which give control over the chemical and physical cues in hydrogel formation. Herein, we combine the best of both systems by developing a synthetic hydrogel with ionic cross-linking of block copolyelectrolytes to rapidly create hydrogels. Reversible addition-fragmentation chain-transfer (RAFT) polymerization was used to synthesize oppositely charged polyelectrolyte molecules and, in turn, modulate the mechanical property of stiffness. The mechanical stiffness of a range of 900-3500 Pa was tuned by varying the number of charged ionic groups, the length of the polymer arms, and the polymer concentration. We demonstrate the synthetic polyelectrolyte hydrogel as an ECM mimic for three-dimensional (3D) in vitro cell models using MCF-7 breast cancer cells.

A Thermosensitive, Chitosan-Based Hydrogel as Delivery System for Antibacterial Liposomes to Surgical Site Infections

Prophylaxis and the treatment of surgical site infections (SSIs) with antibiotics frequently fail due to the antibiotic resistance of bacteria and the ability of bacteria to reside in biofilms (i.e., bacterial clusters in a protective matrix). Therefore, alternative antibacterial treatments are required to combat biofilm infections. The combination of diethyldithiocarbamate (DDC^-) and copper ions (Cu²⁺) exhibited antibiofilm activity against the staphylococci species associated with SSIs; however, the formation of a water-insoluble Cu(DDC)₂ complex limits its application to SSIs. Here, we describe the development and antibiofilm activity of an injectable gel containing a liposomal formulation of Cu(DDC)₂ and Cu²⁺ (lipogel). Lyophilized liposomes were incorporated into a mixture of chitosan (CS) and beta-glycerophosphate (βGP), and the thermosensitive gelling properties of CS-βGP and the lipogel were determined. The liposomes remained stable after lyophilization over six months at 4-6 °C and -20 °C. The sol-gel transition of the gel and lipogel occurred between 33 and 39 °C, independently of sterilization or storage at -20 °C. CS-βGP is biocompatible and the liposomes were released over time. The lipogel prevented biofilm formation over 2 days and killed 98.7% of the methicillin-resistant Staphylococcus aureus and 99.9% of the Staphylococcus epidermidis biofilms. Therefore, the lipogel is a promising new prophylaxis and treatment strategy for local application to SSIs.

Direct contact-mediated non-viral gene therapy using thermo-sensitive hydrogel-coated dressings

Nanotechnologies are being increasingly applied as systems for peptide and nucleic acid macromolecule drug delivery. However systemic targeting of these, or efficient topical and localized delivery remains an issue. A controlled release system that can be patterned and locally administered such as topically to accessible tissue (skin, eye, intestine) would therefore be transformative in realizing the potential of such strategies. We previously developed a technology termed GAG-binding enhanced transduction (GET) to efficiently deliver a variety of cargoes intracellularly, using GAG-binding peptides to mediate cell targeting, and cell penetrating peptides (CPPs) to promote uptake. Herein we demonstrate that the GET transfection system can be used with the moisturizing thermo-reversible hydrogel Pluronic-F127 (PF127) and methyl cellulose (MC) to mediate site specific and effective intracellular transduction and gene delivery through GET nanoparticles (NPs). We investigated hydrogel formulation and the temperature dependence of delivery, optimizing the delivery system. GET-NPs retain their activity to enhance gene transfer within our formulations, with uptake transferred to cells in direct contact with the therapy-laden hydrogel. By using Azowipe™ material in a bandage approach, we were able to show for the first-time localized gene transfer in vitro on cell monolayers. The ability to simply control localization of gene delivery on millimetre scales using contact-mediated transfer from moisture-providing thermo-reversible hydrogels will facilitate new drug delivery methods. Importantly our technology to site-specifically deliver the activity of novel nanotechnologies and gene therapeutics could be transformative for future regenerative medicine.

Comparison ofin-situversusex-situdelivery of polyethylenimine-BMP-2 polyplexes for rat calvarial defect repair via intraoperative bioprinting

Gene therapeutic applications combined with bio- and nano-materials have been used to address current shortcomings in bone tissue engineering due to their feasibility, safety and potential capability for clinical translation. Delivery of non-viral vectors can be altered using gene-activated matrices to improve their efficacy to repair bone defects.Ex-situandin-situdelivery strategies are the most used methods for bone therapy, which have never been directly compared for their potency to repair critical-sized bone defects. In this regard, we first time explore the delivery of polyethylenimine (PEI) complexed plasmid DNA encoding bone morphogenetic protein-2 (PEI-pBMP-2) using the two delivery strategies,ex-situandin-situdelivery. To realize these gene delivery strategies, we employed intraoperative bioprinting (IOB), enabling us to 3D bioprint bone tissue constructs directly into defect sites in a surgical setting. Here, we demonstrated IOB of an osteogenic bioink loaded with PEI-pBMP-2 for thein-situdelivery approach, and PEI-pBMP-2 transfected rat bone marrow mesenchymal stem cells laden bioink for theex-situdelivery approach as alternative delivery strategies. We found thatin-situdelivery of PEI-pBMP-2 significantly improved bone tissue formation compared toex-situdelivery. Despite debates amongst individual advantages and disadvantages ofex-situandin-situdelivery strategies, our results ruled in favor of thein-situdelivery strategy, which could be desirable to use for future clinical applications.

Recent advances in hydrogels-based osteosarcoma therapy

Osteosarcoma (OS), as a typical kind of bone tumors, has a high incidence among adolescents. Traditional tumor eradication avenues for OS such as chemotherapy, surgical therapy and radiation therapy usually have their own drawbacks including recurrence and metastasis. In addition, another serious issue in the treatment of OS is bone repair because the bone after tumor invasion usually has difficulty in repairing itself. Hydrogels, as a synthetic or natural platform with a porous three-dimensional structure, can be applied as desirable platforms for OS treatment. They can not only be used as carriers for tumor therapeutic drugs but mimic the extracellular matrix for the growth and differentiation of mesenchymal stem cells (MSCs), thus providing tumor treatment and enhancing bone regeneration at the same time. This review focuses the application of hydrogels in OS suppression and bone regeneration, and give some suggests on future development.

In situ Hydrogels for Effective Treatment of Cancer: Strategies and Polymers Used

Cancer is a worldwide health ailment with no known boundaries in terms of mortality and occurrence rates, thus is one of the biggest threats to humankind. Hence, there is an absolute need to develop novel therapeutics to bridge the infirmities associated with chemotherapy and conventional surgical methodologies including impairment of normal tissue, compromised drug efficiency and an escalation in side effects. In lieu of this, there's been a surge in curiosity towards development of injectable hydrogels for cancer therapy because local administration of the active pharmaceutical agent offers encouraging advantages such as providing higher effective dose at target site, prolonged retention time of drug, ease of administration, mitigation of dose in vivo ,improved patient compliance. Furthermore, due to its biocompatible nature such systems can significantly reduce the side effects that occur on long-term exposure to chemotherapy. The present review details the most recent advancements in in-situ gel forming polymers (natural and synthetic), polymeric cross-linking methodologies and in-situ gelling mechanisms, focusing on their clinical benefits in cancer therapy.

Formulation of chitosan and chitosan-nanoHAp bioinks and investigation of printability with optimized bioprinting parameters

The development of a chitosan-based bioink that can provide a cell-friendly environment at relatively low concentration and moderate cross-linking conditions is still problematic. Here, we developed amorphous nanohydroxyapatite (nHAp) containing chitosan bioink formulations that can be gelled via the inclusion of glycerol phosphate (GP) and sodium hydrogen carbonate (SHC) into the polymer network under physiological conditions. Rheological analyses indicated that all the formulations showed shear-thinning characteristics compatible with the extrusion-based bioprinting. Also, the chitosan bioinks exhibited more gel-like structure as the weight fraction of nHAp increased from 10 % to 40 %. The printability of the chitosan-based bioinks was assessed and optimized by response surface methodology (RSM). These studies revealed that all the formulations can be successfully printed within the ranges of 50-70 kPa printing pressure and 4-11 mm/s printing speed. Multi-layered chitosan biomaterials with distinct pore structure were successfully fabricated with a high printability index. High cell viability was observed after bioprinting with pre-osteoblastic MC3T3-E1 cells. In conclusion, this study represents for the first time that chitosan biomaterials bearing suitable rheological properties and cellularity can be printed with controllable architecture for 3D bone scaffolds.

Polymer-based thermoresponsive hydrogels for controlled drug delivery

INTRODUCTION

controlled drug delivery through hydrogels is generally limited by the poor barrier that polymeric network can create to diffusion mechanism. Stimuli responsive polymers can help in this way guaranteeing that delivery can be sustained and finely controlled using an external stimulus.

AREA COVERED

this review provides an overview of recent studies about the use of temperature as an external stimulus able to work as an efficient new route of drug's administration. Thermoresponsive hydrogels are discussed and compared in terms of physical properties and mechanism of drug release considering their classification in intrinsically (formed by thermosensitive polymers) and non-intrinsically (polymers with thermosensitive moieties) hydrogels.

EXPERT OPINION

thermoresponsive hydrogels can be developed by using different polymers added or not with micro/nanoparticles of organic or inorganic origin. In both cases the final system represents an innovative way for the local and sustained drug delivery in a specific site of the body. In particular, it is possible to obtain an on-demand release of drug by applying a local increase of temperature to the system.

Local delivery of biocompatible lentinan/chitosan composite for prolonged inhibition of postoperative breast cancer recurrence

Postsurgical localized chemotherapy for breast cancer recurrence (BCR) still faces many problems which dampen researchers' enthusiasm and discounted prognosis. Simple strategies with controllable toxicities are expected to address these hurdles. Lentinan (LNT) has excellent biocompatibility and notable antitumor activity but rather low bioavailability after intravenous or oral administration. Here, a sponge-like LNT/chitosan composite (LNT/CS sponge) was prepared for efficient local delivery to prevent postoperative BCR. The obtained sponges exhibit uniform porosity and sustained release of LNT in vitro and in vivo. Furthermore, the sponges were implanted and showed significant reduction of postsurgical recurrence and suppression of long-term tumor regrowth with favorable biocompatibility in a subcutaneous postsurgical recurrence mouse model. Subsequent studies revealed that LNT can restrain the stemness of breast cancer cells, which may account for the long-term inhibition of tumor relapse. Therefore, LNT/CS sponge has a great potential as a promising alternative for postsurgical BCR.

Recombinant Human Bone Morphogenic Protein-2 Immobilized Fabrication of Magnesium Functionalized Injectable Hydrogels for Controlled-Delivery and Osteogenic Differentiation of Rat Bone Marrow-Derived Mesenchymal Stem Cells in Femoral Head Necrosis Repair

Femoral head necrosis (FHN) is a clinically progressive disease that leads to overwhelming complications without an effective therapeutic approach. In recent decades, transplantation of mesenchymal stem cells (MSCs) has played a promising role in the treatment of FHN in the initial stage; however, the success rate is still low because of unsuitable cell carriers and abridged osteogenic differentiation of the transplanted MSCs. Biopolymeric-derived hydrogels have been extensively applied as effective cell carriers and drug vesicles; they provide the most promising contributions in the fields of tissue engineering and regenerative medicine. However, the clinical potential of hydrogels may be limited because of inappropriate gelation, swelling, mechanical characteristics, toxicity in the cross-linking process, and self-healing ability. Naturally, gelated commercial hydrogels are not suitable for cell injection and infiltration because of their static network structure. In this study, we designed a novel thermogelling injectable hydrogel using natural silk fibroin-blended chitosan (CS) incorporated with magnesium (Mg) substitutes to improve physical cross-linking, stability, and cell osteogenic compatibility. The presented observations demonstrate that the developed injectable hydrogels can facilitate the controlled delivery of immobilized recombinant human bone morphogenic protein-2 (rhBMP-2) and rat bone marrow-derived MSCs (rBMSCs) with greater cell encapsulation efficiency, compatibility, and osteogenic differentiation. In addition, outcomes of in vivo animal studies established promising osteoinductive, bone mineral density, and bone formation rate after implantation of the injectable hydrogel scaffolds. Therefore, the developed hydrogels have great potential for clinical applications of FHN therapy.

Design of Biopolymer-Based Interstitial Therapies for the Treatment of Glioblastoma

Glioblastoma multiforme (GBM) is the most common form of primary brain cancer and has the highest morbidity rate and current treatments result in a bleak 5-year survival rate of 5.6%. Interstitial therapy is one option to increase survival. Drug delivery by interstitial therapy most commonly makes use of a polymer implant encapsulating a drug which releases as the polymer degrades. Interstitial therapy has been extensively studied as a treatment option for GBM as it provides several advantages over systemic administration of chemotherapeutics. Primarily, it can be applied behind the blood–brain barrier, increasing the number of possible chemotherapeutic candidates that can be used and reducing systemic levels of the therapy while concentrating it near the cancer source. With interstitial therapy, multiple drugs can be released locally into the brain at the site of resection as the polymer of the implant degrades, and the release profile of these drugs can be tailored to optimize combination therapy or maintain synergistic ratios. This can bypass the blood–brain barrier, alleviate systemic toxicity, and resolve drug resistance in the tumor. However, tailoring drug release requires appropriate consideration of the complex relationship between the drug, polymer, and formulation method. Drug physicochemical properties can result in intermolecular bonding with the polymeric matrix and affect drug distribution in the implant depending on the formulation method used. This review is focused on current works that have applied interstitial therapy towards GBM, discusses polymer and formulation methods, and provides design considerations for future implantable biodegradable materials.

Evaluation of an Injectable Hydrogel Based on Hyaluronic Acid-chitosan/β-glycerophosphate-loaded Mesenchymal Stem Cells in Enhancing the Therapeutic Efficacy of Myocardial Infarction

Myocardial infarction (MI), which is due to cardiac dysfunction, results in morbidity and mortality. Moreover, the cellular activity of transplanted mesenchymal stem cells (MSCs)generally limits their therapeutic efficacy in the treatment of MI. Here, inject able hyaluronic acid-chitosan/β-glycerophosphate (HA-CS/β-GP) hydrogel-loaded MSCs were prepared, after which their effects on the treatment of MI were investigated. The synthesized HA-CS/β-GP hydrogels exhibited swelling ratio (SR), an in vitro degradation value, and a gelatin time of 82.19 ± 4.1, 88.18% ± 2.4%, and 9 s, respectively. Further, rheological studies revealed that the elastic modulus of the HA-CS/β-GP hydrogels was ≥230 Pa, exhibiting large elastic to viscous modulus ratio, which indicated their mechanical strength. Furthermore, the in vitro 3T3 cell and MSC culture studies confirmed the good biocompatibility of the HA-CS and HA-CS/β-GP hydrogels. The implantation of the synthesized hydrogels in the mouse MI model considerably improved the therapeutic effect of the MSCs (enhanced cardiac function, reduced cardiomyocyte apoptosis, and increased vascularization) for the first time. The innovative synergistic strategy of combining injectable HA-CS and HA-CS/β-GP hydro gels with MSCs might be suitable for the effective treatment of cardiac morbidity due to MIs. This article is protected by copyright. All rights reserved.

Stimuli-Responsive Poly(aspartamide) Derivatives and Their Applications as Drug Carriers

Poly(aspartamide) derivatives, one kind of amino acid-based polymers with excellent biocompatibility and biodegradability, meet the key requirements for application in various areas of biomedicine. Poly(aspartamide) derivatives with stimuli-responsiveness can usually respond to external stimuli to change their chemical or physical properties. Using external stimuli such as temperature and pH as switches, these smart poly(aspartamide) derivatives can be used for convenient drug loading and controlled release. Here, we review the synthesis strategies for preparing these stimuli-responsive poly(aspartamide) derivatives and the latest developments in their applications as drug carriers.

Intra-Operative Bioprinting of Hard, Soft, and Hard/Soft Composite Tissues for Craniomaxillofacial Reconstruction

Reconstruction of complex craniomaxillofacial (CMF) defects is challenging due to the highly organized layering of multiple tissue types. Such compartmentalization necessitates the precise and effective use of cells and other biologics to recapitulate the native tissue anatomy. In this study, intra-operative bioprinting (IOB) of different CMF tissues, including bone, skin, and composite (hard/soft) tissues, is demonstrated directly on rats in a surgical setting. A novel extrudable osteogenic hard tissue ink is introduced, which induced substantial bone regeneration, with ≈80% bone coverage area of calvarial defects in 6 weeks. Using droplet-based bioprinting, the soft tissue ink accelerated the reconstruction of full-thickness skin defects and facilitated up to 60% wound closure in 6 days. Most importantly, the use of a hybrid IOB approach is unveiled to reconstitute hard/soft composite tissues in a stratified arrangement with controlled spatial bioink deposition conforming the shape of a new composite defect model, which resulted in ≈80% skin wound closure in 10 days and 50% bone coverage area at Week 6. The presented approach will be absolutely unique in the clinical realm of CMF defects and will have a significant impact on translating bioprinting technologies into the clinic in the future.

Vesicular drug delivery for the treatment of topical disorders: current and future perspectives

OBJECTIVES

Vesicular drug delivery has become a useful approach for therapeutic administration of pharmaceutical compounds. Lipid vesicles have found application in membrane biology, immunology, genetic engineering and theragnostics. This review summarizes topical delivery, specifically dermal/transdermal, ocular and transungual, via these vesicles, including future formulation perspectives.

KEY FINDINGS

Liposomes and their subsequent derivatives, viz. niosomes, transferosomes, pharmacososmes and ethosomes, form a significant part of vesicular systems that have been successfully utilized in treating an array of topical disorders. These vesicles are thought to be a safe and effective mode of improving the delivery of lipophilic and hydrophilic drugs.

SUMMARY

Several drug molecules are available for topical disorders. However, physicochemical properties and undesirable toxicity have limited their efficacy. Vesicular delivery systems have the potential to overcome these shortcomings due to properties such as high biocompatibility, simplicity of surface modification and suitability as controlled delivery vehicles. However, incorporating these systems into environmentally responsive dispersants such as hydrogels, ionic liquids and deep eutectic solvents may further enhance therapeutic prowess of these delivery systems. Consequently, improved vesicular drug delivery can be achieved by considering combining some of these formulation approaches.

Developing a Glyoxal-Crosslinked Chitosan/Gelatin Hydrogel for Sustained Release of Human Platelet Lysate to Promote Tissue Regeneration

The clinical application of human platelet lysate (HPL) holds promise for tissue regeneration, and the development of an efficient vehicle for its delivery is desired. Chitosan-based hydrogels are potential candidates, but they often exhibit weak mechanical properties. In this study, a chitosan/gelatin (CS-GE) hydrogel crosslinked by glyoxal was fabricated for sustained release of HPL. The influence of HPL on Hs68 fibroblast and human umbilical vein endothelial cell (HUVEC) culture was evaluated, and we found that supplementing 5% HPL in the medium could significantly improve cell proliferation relative to supplementing 10% fetal bovine serum (FBS). Moreover, HPL accelerated the in vitro wound closure of Hs68 cells and facilitated the tube formation of HUVECs. Subsequently, we fabricated CS-GE hydrogels crosslinked with different concentrations of glyoxal, and the release pattern of FITC-dextrans (4, 40 and 500 kDa) from the hydrogels was assessed. After an ideal glyoxal concentration was determined, we further characterized the crosslinked CS-GE hydrogels encapsulated with different amounts of HPL. The HPL-incorporated hydrogel was shown to significantly promote the proliferation of Hs68 cells and the migration of HUVECs. Moreover, the release pattern of transforming growth factor-β1 (TGF-β1) and platelet-derived growth factor-BB (PDGF-BB) from hydrogel was examined in vitro, demonstrating a sustained release profile of the growth factors. Finally, the chick chorioallantoic membrane assay revealed that HPL encapsulation in the hydrogel significantly stimulated angiogenesis in ovo. These results demonstrate the great potential of the crosslinked CS-GE hydrogel to serve as an effective delivery system for HPL to promote tissue regeneration.

Injectable Cell-Laden Hydrogels for Tissue Engineering: Recent Advances and Future Opportunities

Tissue engineering intends to create functionalized tissues/organs for regenerating the injured parts of the body using cells and scaffolds. A scaffold as a supporting substrate affects the cells' fate and behavior, including growth, proliferation, migration, and differentiation. Hydrogel as a biomimetic scaffold plays an important role in cellular behaviors and tissue repair, providing a microenvironment close to the extracellular matrix with adjustable mechanical and chemical features that can provide sufficient nutrients and oxygen. To enhance the hydrogel performance and compatibility with native niche, the cell-laden hydrogel is an attractive choice to mimic the function of the targeted tissue. Injectable hydrogels, due to the injectability, are ideal options for in vivo minimally invasive treatment. Cell-laden injectable hydrogels can be utilized for tissue regeneration in a noninvasive way. This article reviews the recent advances and future opportunities of cell-laden injectable hydrogels and their functions in tissue engineering. It is expected that this strategy allows medical scientists to develop a minimally invasive method for tissue regeneration in clinical settings. Impact statement Cell-laden hydrogels have been vastly utilized in biomedical application, especially tissue engineering. It is expected that this upcoming review article will be a motivation for the community. Although this strategy is still in its early stages, this concept is so alluring that it has attracted all scientists in the community and specialists at academic health centers. Certainly, this approach requires more development, and a bunch of crucial challenges have yet to be solved. In this review, we discuss this various aspects of this approach, the questions that must be answered, the expectations associated with it, and rational restrictions to develop injectable cell-laden hydrogels.

Injectable Thermosensitive Chitosan Solution with β-Glycerophosphate as an Optimal Submucosal Fluid Cushion for Endoscopic Submucosal Dissection

Endoscopic submucosal dissection (ESD) is a surgical procedure to remove early neoplastic lesions in the gastrointestinal tract with the critical issue of perforation. A submucosal fluid cushion, such as normal saline, is used as a cushioning agent to prevent perforation; however, its cushioning maintenance is insufficient for surgery. In this study, we introduce an injectable thermosensitive chitosan solution (CS) with β-glycerophosphate (β-GP) as a submucosal injection agent for ESD. The CS/β-GP system with optimal β-GP concentration showed drastic viscosity change near body temperature while other commercial products did not. Additionally, the injectability of the solution was similar to or greater than other commercial products. The solution with low β-GP concentration showed low cytotoxicity similar to other products. An in vivo preclinical study illustrated maintenance of the high cushioning of the thermosensitive solutions. These results indicate that a CS/β-GP system with optimal β-GP concentration might be used as a submucosal injection agent in ESD, and further studies are needed to validate the effectiveness of the solutions in vivo.

Types of biomaterials useful in brain repair

Biomaterials is an emerging field in the study of brain tissue engineering and repair or neurogenesis. The fabrication of biomaterials that can replicate the mechanical and viscoelastic features required by the brain, including the poroviscoelastic responses, force dissipation, and solute diffusivity are essential to be mapped from the macro to the nanoscale level under physiological conditions in order for us to gain an effective treatment for neurodegenerative diseases. This research topic has identified a critical study gap that must be addressed, and that is to source suitable biomaterials and/or create reliable brain-tissue-like biomaterials. This chapter will define and discuss the various types of biomaterials, their structures, and their function-properties features which would enable the development of next-generation biomaterials useful in brain repair.

Thermosensitive quaternized chitosan hydrogel scaffolds promote neural differentiation in bone marrow mesenchymal stem cells and functional recovery in a rat spinal cord injury model

A thermosensitive quaternary ammonium chloride chitosan/β-glycerophosphate (HACC/β-GP) hydrogel scaffold combined with bone marrow mesenchymal stem cells (BMSCs) transfected with an adenovirus containing the glial cell-derived neurotrophic factor (GDNF) gene (Ad-rGDNF) was applied to spinal cord injury (SCI) repair. The BMSCs from rats were transfected with Ad-rGDNF, resulting in the expression of GDNF mRNA in the BMSCs increasing and their spontaneous differentiation into neural-like cells expressing neural markers such as NF-200 and GFAP. After incubation with HACC/β-GP hydrogel scaffolds for 2 weeks, neuronal differentiation of the BMSCs was confirmed using immunofluorescence (IF), and the expression of GDNF by the BMSCs was detected by Western blot at different time points. MTT assay and scanning electron microscopy confirmed that the HACC scaffold provides a non-cytotoxic microenvironment that supports cell adhesion and growth. Rats with SCI were treated with BMSCs, BMSCs carried by the HACC/β-GP hydrogel (HACC/BMSCs), Ad-rGDNF-BMSCs, or Ad-rGDNF-BMSCs carried by the hydrogel (HACC/GDNF-BMSCs). Animals were sacrificed at 2, 4, and 6 weeks of treatment. IF staining and Western blot were performed to detect the expression of NeuN, NF-200, GFAP, CS56, and Bax in the lesion sites of the injured spinal cord. Upon treatment with HACC/BMSCs, NF200 and GFAP were upregulated but CS56 and Bax were downregulated in the SCI lesion site. Furthermore, transplantation of HACC/GDNF-BMSCs into an SCI rat model significantly improved BBB scores and regeneration of the spinal cord. Thus, HACC/β-GP hydrogel scaffolds show promise for functional recovery in spinal cord injury patients.

Neuroprotective Potential of Ellagic Acid: A Critical Review

Ellagic acid (EA) is a dietary polyphenol present in various fruits, vegetables, herbs, and nuts. It exists either independently or as part of complex structures, such as ellagitannins, which release EA and several other metabolites including urolithins following absorption. During the past few decades, EA has drawn considerable attention because of its vast range of biological activities as well as its numerous molecular targets. Several studies have reported that the oxidative stress-lowering potential of EA accounts for its broad-spectrum pharmacological attributes. At the biochemical level, several mechanisms have also been associated with its therapeutic action, including its efficacy in normalizing lipid metabolism and lipidemic profile, regulating proinflammatory mediators, such as IL-6, IL-1β, and TNF-α, upregulating nuclear factor erythroid 2-related factor 2 and inhibiting NF-κB action. EA exerts appreciable neuroprotective activity by its free radical-scavenging action, iron chelation, initiation of several cell signaling pathways, and alleviation of mitochondrial dysfunction. Numerous in vivo studies have also explored the neuroprotective attribute of EA against various neurotoxins in animal models. Despite the increasing number of publications with experimental evidence, a critical analysis of available literature to understand the full neuroprotective potential of EA has not been performed. The present review provides up-to-date, comprehensive, and critical information regarding the natural sources of EA, its bioavailability, metabolism, neuroprotective activities, and underlying mechanisms of action in order to encourage further studies to define the clinical usefulness of EA for the management of neurological disorders.

Application of a novel thermo-sensitive injectable hydrogel in therapy in situ for drug accurate controlled release

Local drug injection therapy for tumor site, as a neoadjuvant chemotherapy method, shows important significance in clinical application; however, it obtains unsatisfying therapeutic effect due to the serious toxic and side effect in normal tissues caused by drug diffusion or complexity of the preparation. In this article, the influence factors of the gelling time of traditional Chitosan (CTS) thermo-sensitive hydrogels were analyzed, and the gelling properties were improved significantly, and a thermo-sensitive hydrogel with precisely regulated gelling time was obtained through a green and simple preparation method, and the shortest gelling time (gelling time = 27 ± 2 s) of this hydrogel was 5% of that of the common CTS thermo-sensitive hydrogels. After loaded with different chemotherapy drugs with different pH values (gemctiabin hydrochloride, levofloxacin, and 5-foluorouracil), the hydrogels' gelling performance was not affected, while the gelling time could be shortened by 5-foluorouracil, effectively hindering the drug loss at the early stage of sustained release. in vitro and in vivo experiments proved that precise encapsulation toward tumors with different volumes was achieved by the hydrogels, with minimal damage to surrounding normal tissues and higher utilization of drugs in tumor sites, ultimately achieving better tumor therapeutic effect. In conclusion, the new thermo-sensitive hydrogels with precisely regulated gelling time showed great significance and potential for drug delivery and neoadjuvant chemotherapy.

Injectable thermoresponsive hydrogels as drug delivery system for the treatment of central nervous system disorders: A review

The central nervous system (CNS), consisting of the brain, spinal cord, and retina, superintends to the acquisition, integration and processing of peripheral information to properly coordinate the activities of the whole body. Neurodegenerative and neurodevelopmental disorders, trauma, stroke, and brain tumors can dramatically affect CNS functions resulting in serious and life-long disabilities. Globally, the societal and economic burden associated with CNS disorders continues to grow with the ageing of the population thus demanding for more effective and definitive treatments. Despite the variety of clinically available therapeutic molecules, medical interventions on CNS disorders are mostly limited to treat symptoms rather than halting or reversing disease progression. This is attributed to the complexity of the underlying disease mechanisms as well as to the unique biological microenvironment. Given its central importance, multiple barriers, including the blood brain barrier and the blood cerebrospinal fluid barrier, protect the CNS from external agents. This limits the access of drug molecules to the CNS thus contributing to the modest therapeutic successes. Loco-regional therapies based on the deposition of thermoresponsive hydrogels loaded with therapeutic agents and cells are receiving much attention as an alternative and potentially more effective approach to manage CNS disorders. In this work, the current understanding and challenges in the design of thermoresponsive hydrogels for CNS therapy are reviewed. First, the biological barriers that hinder mass and drug transport to the CNS are described, highlighting the distinct features of each barrier. Then, the realization, characterization and biomedical application of natural and synthetic thermoresponsive hydrogels are critically presented. Advantages and limitations of each design and application are discussed with the objective of identifying general rules that could enhance the effective translation of thermoresponsive hydrogel-based therapies for the treatment of CNS disorders.

Intratumoral injection of hydrogel-embedded nanoparticles enhances retention in glioblastoma

Intratumoral drug delivery is a promising approach for the treatment of glioblastoma multiforme (GBM). However, drug washout remains a major challenge in GBM therapy. Our strategy, aimed at reducing drug clearance and enhancing site-specific residence time, involves the local administration of a multi-component system comprised of nanoparticles (NPs) embedded within a thermosensitive hydrogel (HG). Herein, our objective was to examine the distribution of NPs and their cargo following intratumoral administration of this system in GBM. We hypothesized that the HG matrix, which undergoes rapid gelation upon increases in temperature, would contribute towards heightened site-specific retention and permanence of NPs in tumors. BODIPY-containing, infrared dye-labeled polymeric NPs embedded in a thermosensitive HG (HG-NPs) were fabricated and characterized. Retention and distribution dynamics were subsequently examined over time in orthotopic GBM-bearing mice. Results demonstrate that the HG-NPs system significantly improved site-specific, long-term retention of both NPs and BODIPY, with co-localization analyses showing that HG-NPs covered larger areas of the tumor and the peri-tumor region at later time points. Moreover, NPs released from the HG were shown to undergo uptake by surrounding GBM cells. Findings suggest that intratumoral delivery with HG-NPs has immense potential for GBM treatment, as well as other strategies where site-specific, long-term retention of therapeutic agents is warranted.

A Review on Chitosan's Uses as Biomaterial: Tissue Engineering, Drug Delivery Systems and Cancer Treatment

Chitosan, derived from chitin, is a biopolymer consisting of arbitrarily distributed β-(1-4)-linked D-glucosamine and N-acetyl-D-glucosamine that exhibits outstanding properties— biocompatibility, biodegradability, non-toxicity, antibacterial activity, the capacity to form films, and chelating of metal ions. Most of these peculiar properties are attributed to the presence of free protonable amino groups along the chitosan backbone, which also gives it solubility in acidic conditions. Moreover, this biopolymer can also be physically modified, thereby presenting a variety of forms to be developed. Consequently, this polysaccharide is used in various fields, such as tissue engineering, drug delivery systems, and cancer treatment. In this sense, this review aims to gather the state-of-the-art concerning this polysaccharide when used as a biomaterial, providing information about its characteristics, chemical modifications, and applications. We present the most relevant and new information about this polysaccharide-based biomaterial’s applications in distinct fields and also the ability of chitosan and its various derivatives to selectively permeate through the cancer cell membranes and exhibit anticancer activity, and the possibility of adding several therapeutic metal ions as a strategy to improve the therapeutic potential of this polymer.

In vitro study of SDF-1α-loaded injectable and thermally responsive hydrogels for adipose stem cell therapy by SDF-1/CXCR4 axis

Stem cell-based approaches have become a promising therapeutic strategy for treating ischemic diseases. The aim of this study was to develop injectable hydrogel systems for the local release of stromal cell-derived factor-1α (SDF-1α) to recruit adipose stem cells (ASCs) that express CXCR4 to achieve stem cell therapy and therapeutic angiogenesis. Thermoresponsive and injectable chitosan (CS)/β-glycerophosphate disodium salt pentahydrate (βGP) hydrogels with different concentrations of hyaluronic acid (HA) were designed and fabricated to achieve local and sustained release of SDF-1α for ASC recruitment. Herein, the material structures, physical properties, gelation temperature, and gelation time of hydrogels with different compositions were determined. The incorporation of 0.9% HA in CS-based hydrogels not only enhanced the gelation time but also increased the strength of the hydrogels. In addition, the results revealed that the thermoresponsive and injectable CS/βGP/HA hydrogels showed good biocompatibility. In addition, the in vitro release profiles showed that the hydrogels achieved sustained release of SDF-1α over 7 days and enhanced ASC migration. The results revealed that the hydrogels with HA enhanced the sustained release effect compared with the hydrogel without HA, indicating that the HA content regulated the physical and release properties of the injectable hydrogels. Therefore, thermoresponsive and injectable CS/βGP/HA hydrogels may provide an alternative for treating ischemic diseases via SDF-1/CXCR4 axis for ASC recruitment and retention.

Injectability of Thermosensitive, Low-Concentrated Chitosan Colloids as Flow Phenomenon through the Capillary under High Shear Rate Conditions

Low-concentrated colloidal chitosan systems undergoing a thermally induced sol-gel phase transition are willingly studied due to their potential use as minimally invasive injectable scaffolds. Nevertheless, instrumental injectability tests to determine their clinical utility are rarely performed. The aim of this work was to analyze the flow phenomenon of thermosensitive chitosan systems with the addition of disodium β-glycerophosphate through hypodermic needles. Injectability tests were performed using a texture analyzer and hypodermic needles in the sizes 14G-25G. The rheological properties were determined by the flow curve, three-interval thixotropy test (3ITT), and Cox-Merz rule. It was found that reducing the needle diameter and increasing its length and the crosshead speed increased the injection forces. It was claimed that under the considered flow conditions, there was no need to take into account the viscoelastic properties of the medium, and the model used to predict the injection force, based solely on the shear-thinning nature of the experimental material, showed very good agreement with the experimental data in the shear rate range of 200-55,000 s-1. It was observed that the increase in the shear rate value led to macroscopic structural changes of the chitosan sol caused by the disentangling and ordering of the polysaccharide chains along the shear field.

Strategies to improve ellagic acid bioavailability: from natural or semisynthetic derivatives to nanotechnological approaches based on innovative carriers

Ellagic acid (EA) is a polyphenolic compound whose dietary consumption is mainly associated with the intake of red fruits, including pomegranates, strawberries, blackberries, blackcurrants, raspberries, grapes or dried fruits, like walnuts and almonds. A number of studies indicate that EA exerts health-beneficial effects against several chronic pathologies associated with oxidative damage, including different kinds of cancer, cardiovascular and neurodegenerative diseases. Furthermore, EA possesses wound-healing properties, antibacterial and antiviral effects, and acts as a systemic antioxidant. However, clinical applications of this polyphenol have been hampered and prevented by its poor water solubility (9.7 ± 3.2 μg ml^-1 in water) and pharmacokinetic profile (limited absorption rate and plasma half-life <1 h after ingestion of pomegranate juice), properties due to the chemical nature of the organic heterotetracyclic compound. Little has been reported on efficient strategies to enhance EA poor oral bioavailability, including chemical structure modifications, encapsulation within nano-microspheres to be used as carriers, and molecular dispersion in polymer matrices. In this review we summarize the experimental approaches investigated so far in order to improve EA pharmacokinetics, supporting the hypothesis that enhancement in EA solubility is a feasible route for increasing its oral absorption.

Stimuli-responsive In situ gelling system for nose-to-brain drug delivery

The diagnosis and treatment of neurological ailments always remain an utmost challenge for research fraternity due to the presence of BBB. The intranasal route appeared as an attractive and alternative route for brain targeting of therapeutics without the intrusion of BBB and GI exposure. This route directly and effectively delivers the therapeutics to different regions of the brain via olfactory and trigeminal nerve pathways. However, shorter drug retention time and mucociliary clearance curtail the efficiency of the intranasal route. The in situ mucoadhesive gel overthrow the limitations of direct nose-to-brain delivery by not only enhancing nasal residence time but also minimizing the mucociliary clearance and enzymatic degradation. This delivery system further improves the nasal absorption as well as bioavailability of drugs in the brain. The in situ mucoadhesive gel is a controlled and sustained release system that facilitates the absorption of various proteins, peptides and other larger lipophilic and hydrophilic moieties. Owing to multiple benefits, in situ gelling system has been widely explored to target the brain via nasal route. However, very few review works are reported which explains the application of in situ nasal gel for brain delivery of CNS acting moieties. Hence, in this piece of work, we have initially discussed the global statistics of neurological disorders reported by WHO and other reputed organizations, nasal anatomy, mechanism and challenges of nose-to-brain drug delivery. The work mainly focused on the use of different stimuli-responsive polymers, specifically thermoresponsive, pH-responsive, and ion triggered systems for the development of an effective and controlled dosage form, i.e., in situ nasal gel for brain targeting of bioactives. We have also highlighted the origin, structure, nature and phase transition behavior of the smart polymers found suitable for nasal administration, including poloxamer, chitosan, EHEC, xyloglucan, Carbopol, gellan gum and DGG along with their application in the treatment of neurological disorders. The article is aimed to gather all the information of the past 10 years related to the development and application of stimuli-responsive in situ nasal gel for brain drug delivery.

Injectable thermosensitive chitosan/gelatin-based hydrogel carried erythropoietin to effectively enhance maxillary sinus floor augmentation in vivo

OBJECTIVE

Maxillary sinus floor augmentation (MSFA) is commonly used to increase the alveolar bone height in the posterior maxilla before implant placement. In the present study, we evaluated if the injectable thermosensitive chitosan/β-sodium glycerophosphate disodium salt hydrate/gelatin (CS/GP/GA) hydrogel carried erythropoietin (EPO) could enhance the new bone formation for MSFA in vivo.

METHODS

EPO-CS/GP/GA hydrogel was prepared by ionic crosslinking. Then, characteristics of EPO-CS/GP/GA were evaluated by morphology, injectable property and pH on the gelling time (GT). The release profile of EPO was evaluated by enzyme linked immunosorbent assay (ELISA), and effects of EPO on proliferation and osteoblastic differentiation of bone marrow stromal cells (BMSC) were analyzed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and reverse transcription quantitative real-time PCR (RT-qPCR), respectively. Finally, EPO-CS/GP/GA was injected into the maxillary sinus floor of the rabbit to test the potential application for MSFA.

RESULTS

Results showed that GT was decreased with the increase of pH value. The GT was 110±15s at pH 7.0. SEM images showed that the CS/GP/GA hydrogel had a sponge network structure. Results from ELISA assay revealed that the cumulative release of EPO from the EPO-CS/GP/GA hydrogel reached 67% at 4h, and 94% at 15 days. MTT assay showed that EPO within EPO-CS/GP/GA hydrogel could significantly promote proliferation of BMSCs compared to control group (p<0.001) . Results of RT-qPCR assays demonstrated that the expression of Sp7, Runx2, Col I and Alp were significantly increased from EPO-CS/GP/GA group compared to control group on day 14 (p<0.001). Importantly, EPO-CS/GP/GA hydrogel could significantly induce bone formation (81.98mm³) compared with control group (43.11mm³) after 12 weeks post-implantation in vivo. The calculation of thickness of mesenchymal condensation indicated that thickness of mesenchymal condensation was significantly increased from EPO-CS/GP/GA group (∼121.4μm) compared to control group (∼37μm) resulting in enhancing intramembranous ossification.

SIGNIFICANCE

The EPO-CS/GP/GA hydrogel provides a novel strategy for MSFA with a minimally invasive way.

Synthesis and characterization of thermosensitive hydrogel based on quaternized chitosan for intranasal delivery of insulin

Nasal administration is a form of systemic administration in which drugs are insufflated through the nasal cavity. Steroids, nicotine replacement, antimigraine drugs, and peptide drugs are examples of the available systematically active drugs as nasal sprays. For diabetic patients who need to use insulin daily, the nasal pathway can be used as an alternative to subcutaneous injection. In this regard, intranasal insulin delivery as a user-friendly and systemic administration has recently attracted more attention. In this study, a novel formulation consists of chitosan, chitosan quaternary ammonium salt (HTCC), and gelatin (Gel) was proposed and examined as a feasible carrier for intranasal insulin administration. First, the optimization of the chitosan-HTCC hydrogel combination has done. Afterward, Gel with various amounts blended with the chitosan-HTCC optimized samples. In the next step, swelling rate, gelation time, degradation, adhesion, and other mechanical, chemical, and biological properties of the hydrogels were studied. Finally, insulin in clinical formulation and dosage was blended with optimized thermosensitive hydrogel and the release procedure of insulin was studied with electrochemiluminescence technique. The optimal formulation (consisted of 2 wt% chitosan, 1 wt% HTCC, and 0.5 wt% Gel) showed low gelation time, uniform pore structure, and the desirable swelling rate, which were resulted in the adequate encapsulation and prolonged release of insulin in 24 H. The optimal samples released 65% of the total amount of insulin in the first 24 H, which is favorable for this study.

Injectable and In Situ-Formable Thiolated Chitosan-Coated Liposomal Hydrogels as Curcumin Carriers for Prevention of In Vivo Breast Cancer Recurrence

To improve water solubility and bioavailability, curcumin (Cur) was encapsulated by liposomes (Cur-Lip), which was further coated with thiolated chitosan (CSSH) to form liposomal hydrogels (CSSH/Cur-Lip gel). The hydrogels were thermosensitive with in situ injectable performance, which were fluidic at room temperature and gelled quickly at 37 °C. The cumulative release ratio of the 200 μM CSSH/Cur-Lip gel was 31.57 ± 1.34% at 12 h, which could effectively delay the release of curcumin. Worthily, the resilient hydrogels were compressive even after five cycles of compression. The cytotoxicity test indicated that the liposomal hydrogels had good cytocompatibility, but after encapsulation of curcumin, MCF-7 cells were suppressed and killed dramatically after 72 h. The in vivo breast cancer recurrence experiment showed that the CSSH/Cur-Lip gel inhibited breast cancer recurrence after tumors were resected, and the tissue of defect in the CSSH/Cur-Lip gel group was repaired. The results showed that the drug-loaded liposomal hydrogels can deliver curcumin continuously and exerted an excellent tumoricidal effect in vitro and in vivo. The injectable, in situ-formable, and thermosensitive CSSH/Cur-Lip gel can be designed as a promising novel drug delivery vehicle to be used as carriers for local accurate and sustained drug delivery to minimize burst release and as tissue engineering scaffolds for tissue regeneration after tumor resection.

IGF-1C domain-modified hydrogel enhanced the efficacy of stem cells in the treatment of AMI

Background

Due to the low survival rate of cell transplantation, stem cell has not been widely used in clinical treatment of acute myocardial infarction (AMI). In this study, we immobilized the C domain peptide of insulin-like growth factor-1 on chitosan (CS-IGF-1C) to obtain bioactive hydrogel. The purpose was to investigate whether CS-IGF-1C hydrogel incorporated with human placenta–derived mesenchymal stem cells (hP-MSCs) can boost the survival of hP-MSCs and enhance their therapeutic effects.

Methods

hP-MSCs, which continuously expressed green fluorescent protein (GFP) and firefly luciferase (Fluc), were transplanted with CS-IGF-1C hydrogel into a mouse myocardial infarction model. Cell survival was detected by bioluminescence imaging (BLI), and cardiac function was measured by echocardiogram. Real-time PCR and histological analysis were used to explore the therapeutic mechanism of CS-IGF-1C hydrogel.

Results

CS-IGF-1C hydrogel could induce the proliferation of hP-MSCs and exert anti-apoptotic effects in vitro. The Calcine-AM/PI staining results showed that hP-MSCs seeded on CS-IGF-1C hydrogel could protect neonatal mouse ventricular cardiomyocytes (NMVCs) against oxidative stress. It was observed by BLI that CS-IGF-1C hydrogel injected into ischemic myocardium could improve the survival rate of hP-MSCs. Histology analysis indicated that co-transplantation of the CS-IGF-1C hydrogel and hP-MSCs could increase angiogenesis, reduce collagen deposition, ameliorate left ventricular expanded, and further promote the recovery of cardiac function. Besides, we found that the inflammatory response was inhibited and the expression of apoptosis-related genes was downregulated by CS-IGF-1C hydrogel.

Conclusions

CS-IGF-1C hydrogel provides a conducive microenvironment for cells and significantly boosts the survival of hP-MSCs in mouse myocardial infarction model, which suggest that it may be a potential candidate for prolonging the therapeutic effect of hP-MSCs during AMI.