Novel injectable thermosensitive hydrogels for delivering hyaluronic acid-doxorubicin nanocomplexes to locally treat tumors

Intraperitoneal drug delivery systems for peritoneal carcinomatosis: Bridging the gap between research and clinical implementation

Several abdominal-located cancers develop metastasis within the peritoneum, what is called peritoneal carcinomatosis (PC), constituting a clinical challenge in their therapeutical management, often leading to poor prognoses. Current multidisciplinary strategies, including cytoreductive surgery (CRS), hyperthermic intraperitoneal chemotherapy (HIPEC), and pressurized intraperitoneal aerosol chemotherapy (PIPAC), demonstrate efficacy but have limitations. In response, alternative strategies are explored in the drug delivery field for intraperitoneal chemotherapy. Controlled drug delivery offers a promising avenue, maintaining localized drug concentrations for optimal PC management. Drug delivery systems (DDS), including hydrogels, implants, nanoparticles, and hybrid systems, show potential for sustained and region-specific drug release. The present review aims to offer an overview of the advances and current designs of DDS for PC chemotherapy administration, focusing on their composition, main characteristics, and principal experimental outcomes, highlighting the importance of biomaterial rationale design and in vitro/vivo models for their testing. Moreover, since clinical data for human subjects are scarce, we offer a critical discussion of the gap between bench and bedside in DDS translation, emphasizing the need for further research.

Rheological and Injectability Evaluation of Sterilized Poloxamer-407-Based Hydrogels Containing Docetaxel-Loaded Lipid Nanoparticles

Nanostructured lipid carriers (NLCs) have the potential to increase the bioavailability and reduce the side effects of docetaxel (DTX). However, only a small fraction of nanoparticles given intravenously can reach a solid tumor. In situ-forming gels combined with nanoparticles facilitate local administration and promote drug retention at the tumor site. Injectable hydrogels based on poloxamer 407 are excellent candidates for this hybrid nanoparticle-hydrogel system because of their thermoresponsive behavior and biocompatibility. Therefore, this work aimed to develop injectable poloxamer hydrogels containing NLCs for intratumoral delivery of DTX. To ensure sterility, the obtained hydrogels were autoclaved (121 °C for 15 min) after preparation. Then, the incorporation of NLCs into the poloxamer hydrogels and the impact of steam sterilization on the nanocomposite hydrogels were evaluated concerning sol-gel transition, injectability, and physicochemical stability. All formulations were extruded through the tested syringe-needle systems with acceptable force (2.2-13.4 N) and work (49.5-317.7 N·mm) of injection. Following steam sterilization, injection became easier in most cases, and the physicochemical properties of all hydrogels remained practically unchanged according to the spectroscopical and thermal analysis. The rheological evaluation revealed that the nanocomposite hydrogels were liquid at 25 °C and underwent rapid gelation at 37 °C. However, their sterilized counterparts gelled at 1-2 °C above body temperature, suggesting that the autoclaving conditions employed had rendered these nanocomposite hydrogels unsuitable for local drug delivery.

Dual-targeting CD44 and mucin by hyaluronic acid and 5TR1 aptamer for epirubicin delivery into cancer cells: Synthesis, characterization, in vitro and in vivo evaluation

One of the revolutionized cancer treatment is active targeting nanomedicines. This study aims to create a dual-targeted drug delivery system for Epirubicin (EPI) to cancer cells. Hyaluronic acid (HA) is the first targeting ligand, and 5TR1 aptamer (5TR1) is the second targeting ligand to guide the dual-targeted drug delivery system to the cancer cells. HA is bound to highly expressed receptors like CD44 on cancer cells. 5TR1, DNA aptamer, is capable of recognizing MUC1 glycoprotein, which is overexpressed in cancer cells. The process involved binding EPI and 5TR1 to HA using adipic acid dihydrazide (AA) as a linker. The bond between the components was confirmed using 1H NMR. The binding of 5TR1 to HA-AA-EPI was confirmed using gel electrophoresis. The particle size (132.6 ± 9 nm) and Zeta Potential (-29 ± 4.4 mV) were measured for the final nanoformulation (HA-AA-EPI-5TR1). The release of EPI from the HA-AA-EPI-5TR1 nanoformulation was also studied at different pH levels. In the acidic pH (5.4 and 6.5) release pattern of EPI from the HA-AA-EPI-5TR1 nanoformulation was higher than physiological pH (7.4). The cytotoxicity and cellular uptake of the synthetic nanoformula were evaluated using MTT and flow cytometry analysis. Flow cytometry and cellular cytotoxicity studies were exhibited in a negative MUC1-cell line (CHO) and two positive MUC1+cell lines (MCF-7 and C26). Results confirmed that there is a notable contrast between the dual-targeted (HA-AA-EPI-5TR1) and single-targeted (HA-AA-EPI) nanoformulation in MCF-7 and C26 cell lines (MUC1+). In vivo studies showed that HA-AA-EPI-5TR1 nanoformulation has improved efficiency with limited side effect in C26 tumor-bearing mice. Also, Fluorescence imaging and pathological evaluation showed reduced side effects in the heart tissue of mice receiving HA-AA-EPI-5TR1 than free EPI. So, this targeted approach effectively delivers EPI to cancer cells with reduced side effects.

Inhibiting HER3 Hyperphosphorylation in HER2-Overexpressing Breast Cancer through Multimodal Therapy with Branched Gold Nanoshells

Treatment failure in breast cancers overexpressing human epidermal growth factor receptor 2 (HER2) is associated mainly to the upregulation of human epidermal growth factor receptor 3 (HER3) oncoprotein linked to chemoresitence. Therefore, to increase patient survival, here a multimodal theranostic nanoplatform targeting both HER2 and HER3 is developed. This consists of doxorubicin-loaded branched gold nanoshells functionalized with the near-infrared (NIR) fluorescent dye indocyanine green, a small interfering RNA (siRNA) against HER3, and the HER2-specific antibody Transtuzumab, able to provide a combined therapeutic outcome (chemo- and photothermal activities, RNA silencing, and immune response). In vitro assays in HER2+ /HER3+ SKBR-3 breast cancer cells have shown an effective silencing of HER3 by the released siRNA and an inhibition of HER2 oncoproteins provided by Trastuzumab, along with a decrease of the serine/threonine protein kinase Akt (p-AKT) typically associated with cell survival and proliferation, which helps to overcome doxorubicin chemoresistance. Conversely, adding the NIR light therapy, an increment in p-AKT concentration is observed, although HER2/HER3 inhibitions are maintained for 72 h. Finally, in vivo studies in a tumor-bearing mice model display a significant progressively decrease of the tumor volume after nanoparticle administration and subsequent NIR light irradiation, confirming the potential efficacy of the hybrid nanocarrier.

Composite Hydrogels of Ultrasound-Assisted-Digested Formic Acid-Decellularized Extracellular Matrix and Sacchachitin Nanofibers Incorporated with Platelet-Rich Plasma for Diabetic Wound Treatment

In this study, an ultrasound-assisted digestion method of a formic acid-decellularized extracellular matrix (dECM) of porcine skin was developed and optimized to form UdECM hydrogels for diabetic wound healing. Results demonstrated that ultrasonication improved the extraction rate of collagen from dECM samples, preserved the collagen content of dECM, reduced residual cells, and extracted greater DNA contents. Scanning electron microscope (SEM) analyses were performed, which demonstrated the optimal porosity on the surface and density of the cross-section in the hydrogel structure, which could control the release of growth factors embedded in UdECM hydrogels at desirable rates to boost wound healing. A wound-healing study was conducted with six different composite hydrogels, both empty materials and materials enriched with rat platelet-rich plasma (R-PRP), sacchachitin nanofibers (SCNFs), and TEMPO-oxidized sacchachitin in diabetic rats. The assessment based on scars stained with hematoxylin and eosin (H&E), Masson's trichrome (MT), and a cluster of differentiation 31 (CD31) staining showed that the UdECM/SC/R-PRP treatment group had the most significant efficacy of promoting healing and even recovery of diabetic wounds to normal tissues. UdECM/R-PRP and UdECM/SCNFs demonstrated better healing rates than UdECM hydrogel scaffolds, which had only recovered 50% resemblance to normal skin. Treatment with both UdECM/TEMPO 050 and UdECM/TEMPO 050/R-PRP hydrogel scaffolds was ranked last, with even poorer efficacy than UdECM hydrogels. In summary, formulated UdECM and SCNF hydrogels loaded with PRP showed synergistic effects of accelerating wound healing and ultimately stimulating the wound to recover as functional tissues. This newly UdECM/SCNF composite hydrogel has promising potential for healing and regenerating diabetic wounds.

Injectable Poloxamer Hydrogels for Local Cancer Therapy

The widespread push to invest in local cancer therapies comes from the need to overcome the limitations of systemic treatment options. In contrast to intravenous administration, local treatments using intratumoral or peritumoral injections are independent of tumor vasculature and allow high concentrations of therapeutic agents to reach the tumor site with minimal systemic toxicity. Injectable biodegradable hydrogels offer a clear advantage over other delivery systems because the former requires no surgical procedures and promotes drug retention at the tumor site. More precisely, in situ gelling systems based on poloxamers have garnered considerable attention due to their thermoresponsive behavior, biocompatibility, ease of preparation, and possible incorporation of different anticancer agents. Therefore, this review focuses on the use of injectable thermoresponsive hydrogels based on poloxamers and their physicochemical and biological characterization. It also includes a summary of these hydrogel applications in local cancer therapies using chemotherapy, phototherapy, immunotherapy, and gene therapy.

Injectable Thermoresponsive Hydrogels for Cancer Therapy: Challenges and Prospects

The enervating side effects of chemotherapeutic drugs have necessitated the use of targeted drug delivery in cancer therapy. To that end, thermoresponsive hydrogels have been employed to improve the accumulation and maintenance of drug release at the tumour site. Despite their efficiency, very few thermoresponsive hydrogel-based drugs have undergone clinical trials, and even fewer have received FDA approval for cancer treatment. This review discusses the challenges of designing thermoresponsive hydrogels for cancer treatment and offers suggestions for these challenges as available in the literature. Furthermore, the argument for drug accumulation is challenged by the revelation of structural and functional barriers in tumours that may not support targeted drug release from hydrogels. Other highlights involve the demanding preparation process of thermoresponsive hydrogels, which often involves poor drug loading and difficulties in controlling the lower critical solution temperature and gelation kinetics. Additionally, the shortcomings in the administration process of thermosensitive hydrogels are examined, and special insight into the injectable thermosensitive hydrogels that reached clinical trials for cancer treatment is provided.

From crosslinking strategies to biomedical applications of hyaluronic acid-based hydrogels: A review

Hyaluronic acid (HA) is not only a natural anionic polysaccharide with excellent biocompatibility, biodegradability, and moisturizing effect, but also an essential factor that can affect angiogenesis, inflammation, cell behavior, which has a wide range of applications in the biomedical field. Among them, HA-based hydrogels formed by various physical or chemical crosslinking strategies are particularly striking. They not only retain the physiological function of HA, but also have the skeleton function of hydrogel, which further expands the application of HA. However, HA-based natural hydrogels generally have problems such as insufficient mechanical strength and susceptibility to degradation by hyaluronidase, which limits their application to a certain extent. To solve such problems, researchers have prepared a variety of HA-based multifunctional hydrogels with remarkable properties in recent years by adopting various structural modification methods or novel crosslinking strategies, as well as introducing functionally reactive molecules or moieties, which have extended the application scope. This manuscript systematically introduced common crosslinking strategies of HA-based hydrogels and highlighted the development of novel HA-based hydrogels in anticancer drug delivery, cartilage repair, three-dimensional cell culture, skin dressing and other fields. We hope to provide some references for the subsequent development of HA-based hydrogels in the biomedical field.

'Two-faces' of hyaluronan, a dynamic barometer of disease progression in tumor microenvironment

Hyaluronan (HA) is a linear polysaccharide consisting of disaccharide units which are the D-glucuronic acid and N-acetyl-D-glucosamine. As the largest component of the extracellular matrix in microenvironment, HA polymers with different molecular weights vary in properties to molecular biology function. High molecular weight HA (HMW-HA) is mainly found in normal tissue or physiological condition, and exhibits lubrication and protection properties due to its good water retention and viscoelasticity. On the other hand, an increase in HA catabolism leads to the accumulation of low molecular weight HA (LMW-HA) under pathological circumstances such as inflammation, pre-cancerous and tumor microenvironment. LMW-HA acts as extracellular signals to enhance tumorigenic and metastatic phenotype, such as energy reprogramming, angiogenesis and extracellular matrix (ECM) remodeling. This review discusses the basic properties of this simplest carbohydrate molecule in ECM with enormous potential, and its regulatory role between tumorigenesis and microenvironmental homeostasis. The extensive discoveries of the mechanisms underlying the roles of HA in various physiological and pathological processes would provide more information for future research in the fields of biomimetic materials, pharmaceutical and clinical applications.

Preparation and Characterization of Extracellular Matrix Hydrogels Derived from Acellular Cartilage Tissue

Decellularized matrices can effectively reduce severe immune rejection with their cells and eliminated nucleic acid material and provide specific environments for tissue repair or tissue regeneration. In this study, we prepared acellular cartilage matrix (ACM) powder through the decellularization method and developed ACM hydrogels by physical, chemical, and enzymatic digestion methods. The results demonstrated that the small size group of ACM hydrogels exhibited better gel conditions when the concentration of ACM hydrogels was 30 and 20 mg/mL in 1N HCl through parameter adjustment. The data also confirmed that the ACM hydrogels retained the main components of cartilage: 61.18% of glycosaminoglycan (GAG) and 78.29% of collagen, with 99.61% of its DNA removed compared to samples without the decellularization procedure (set as 100%). Through turbidimetric gelation kinetics, hydrogel rheological property analysis, and hydrogel tissue physical property testing, this study also revealed that increasing hydrogel concentration is helpful for gelation. Besides, the ex vivo test confirmed that a higher concentration of ACM hydrogels had good adhesive properties and could fill in cartilage defects adequately. This study offers useful information for developing and manufacturing ACM hydrogels to serve as potential alternative scaffolds for future cartilage defect treatment.

Advances in the therapeutic delivery and applications of functionalized Pluronics: A critical review

Pluronic (PEO-PPO-PEO) block copolymers can form nano-sized micelles with a structure composed of a hydrophobic PPO core and hydrophilic PEO shell layer. Pluronics are U.S. Food and Drug Administration approved polymers, which are widely used for solubilization of drugs and their delivery, gene/therapeutic delivery, diagnostics, and tissue engineering applications due to their non-ionic properties, non-toxicity, micelle forming ability, excellent biocompatibility and biodegradability. Although Pluronics have been employed as drug carrier systems for several decades, numerous issues such as rapid dissolution, shorter residence time in biological media, fast clearance and weak mechanical strength have hindered their efficacy. Pluronics have been functionalized with pH-sensitive, biological-responsive moieties, antibodies, aptamers, folic acid, drugs, different nanoparticles, and photo/thermo-responsive hydrogels. These functionalization strategies enable Pluronics to act as stimuli responsive and targeted drug delivery vehicles. Moreover, Pluronics have emerged in nano-emulsion formulations and have been utilized to improve the properties of cubosomes, dendrimers and nano-sheets, including their biocompatibility and aqueous solubility. Functionalization of Pluronics results in the significant improvement of target specificity, loading capacity, biocompatibility of nanoparticles and stimuli responsive hydrogels for the promising delivery of a range of drugs. Therefore, this review presents an overview of all advancements (from the last 15 years) in functionalized Pluronics, providing a valuable tool for industry and academia in order to optimize their use in drug or therapeutic delivery, in addition to several other biomedical applications.

Intratumoral Administration of Thermosensitive Hydrogel Co-Loaded with Norcantharidin Nanoparticles and Doxorubicin for the Treatment of Hepatocellular Carcinoma

Background

The efficacy of systemic chemotherapy for hepatocellular carcinoma (HCC) is predominantly hampered by low accumulation in tumor tissue and the high systemic toxicity of anticancer drugs. In this study, we designed an in situ drug-loaded injectable thermosensitive hydrogel system for the simultaneous delivery of norcantharidin-loaded nanoparticles (NCTD-NPs) and doxorubicin (Dox) via intratumoral administration to HCC tumors.

Methods

NCTD-NPs were prepared by the thin film dispersion method using PCEC polymers as the carrier. Then, NCTD-NPs and Dox were co-encapsulated in a thermosensitive hydrogel based on Pluronic F127 (PF127) to construct a dual drug-loaded hydrogel system. The rheological properties of the drug-loaded hydrogel were studied using a rheometer. Drug release of the drug-loaded hydrogel and cytotoxicity in HepG2 cells were evaluated in vitro. An H22 tumor-bearing mice model was used to assess the in vivo antitumor activity of the drug-loaded hydrogel via intratumoral administration.

Results

The prepared drug-loaded hydrogel exhibited good thermal-sensitive properties, which remained liquid at room temperature and rapidly transformed into a non-flowing gel at body temperature, and released the drugs in a sustained manner. In vitro studies revealed that the drug-loaded hydrogel exhibited remarkable antiproliferative activity in HepG2 cells compared to free drugs. In vivo antitumor efficacy experiments showed that the drug-loaded hydrogel significantly suppressed tumor growth, alleviated side effects, and prolonged the survival time of mice bearing H22 tumors compared to the other groups. Moreover, immunohistochemical staining revealed that the expression of Ki-67 and CD31 in the drug-loaded hydrogel group was significantly lower than that in the other groups (P < 0.05), indicating that the drug-loaded hydrogel effectively inhibited tumor proliferation and angiogenesis.

Conclusion

The formulated hybrid thermosensitive hydrogel system with sustained drug release and enhanced therapeutic efficacy was demonstrated to be a promising strategy for the local-regional treatment of HCC via intratumoral administration.

Strontium ranelate-laden near-infrared photothermal-inspired methylcellulose hydrogel for arthritis treatment

Rheumatoid arthritis (RA) is of foremost concern among long-term autoimmune disorders, as it leads to inflammation, exudates, chondral degeneration, and painful joints. Because RA severity often fluctuates over time, a local drug delivery method that titrates release of therapeutics to arthritis bioactivity should represent a promising paradigm of RA therapy. Given the local nature of RA chronic illnesses, polysaccharide-drug delivering systems have the promise to augment therapeutic outcomes by offering controlled release of bioactive materials, diminishing the required frequency of administration, and preserving therapeutic levels in affected pathological regions. Herein, an intra-articular photothermal-laden injectable methylcellulose (MC) polymeric hydrogel carrier incorporating strontium ranelate (SrR) and sodium chloride was investigated to resolve these issues. Physicochemical and cellular characteristics of the MC carrier system were thoroughly evaluated. The slow release of SrR, enhancement of the material mechanical strength, and the potential of the non-invasive near-infrared photothermal gel to improve blood circulation and suppress inflammation in a mini-surgical model of RA were examined. Biocompatibility and suppression of intracellular ROS-induced inflammation were observed. This multifunctional photothermal MC hydrogel carrier is anticipated to be an alternative approach for future orthopedic disease treatment.

Evaluation of the activity of a chemo-ablative, thermoresponsive hydrogel in a murine xenograft model of lung cancer

BACKGROUND

Minimally invasive intratumoural administration of thermoresponsive hydrogels, that transition from liquid to gel in response to temperature, has been proposed as a potential treatment modality for solid tumours. The aim of this study was to assess the inherent cytotoxicity of a poloxamer-based thermoresponsive hydrogel in a murine xenograft model of lung cancer.

METHODS

In vitro viability assessment was carried out in a lung cancer (A549) and non-cancerous (Balb/c 3T3 clone A31) cell line. Following intratumoural administration of saline or the thermoresponsive hydrogel to an A549 xenograft model in female Athymic Nude-Foxn1nu mice (n = 6/group), localisation was confirmed using IVIS imaging. Tumour volume was assessed using callipers measurements over 14 days. Blood serum was analysed for liver and kidney damage and ex vivo tissue samples were histologically assessed.

RESULTS

The thermoresponsive hydrogel demonstrated a dose-dependent cancer cell-specific toxicity in vitro and was retained in situ for at least 14 days in the xenograft model. Tumour volume increase was statistically significantly lower than saline treated control at day 14 (n = 6, p = 0.0001), with no associated damage of hepatic or renal tissue observed.

CONCLUSIONS

Presented is a poloxamer-based thermoresponsive hydrogel, suitable for intratumoural administration and retention, which has demonstrated preliminary evidence of local tumour control, with minimal off-site toxicity.

A Novel Composite Hydrogel Composed of Formic Acid-Decellularized Pepsin-Soluble Extracellular Matrix Hydrogel and Sacchachitin Hydrogel as Wound Dressing to Synergistically Accelerate Diabetic Wound Healing

Extracellular matrix (ECM) hydrogel can create a favorable regenerative microenvironment and act as a promising dressing for accelerating the healing of diabetic wound. In this study, a simple and effective decellularization technique was developed and optimized to obtain acellular extracellular matrix (aECM) from porcine skin. It was found that decellularization at 30% formic acid for 72 h effectively decellularized porcine skin while retaining >75% collagen and ~37% GAG in the aECM with no presence of nuclei of cellular remnants. aECM hydrogel was fabricated by digesting aECM with pepsin in various acidic solutions (0.1 N HCl, glycolic acid (GA) and 2-pyrrolidone-5-carboxylic acid (PCA)) and then treated with a pH-controlled neutralization and temperature-controlled gelation procedure. Based on physical characterizations, including SDS-PAGE, rheological analysis and SEM analysis, aECM_HCl hydrogels fabricated at 25 mg/mL in 0.1 N HCl were selected. Four polymeric ECM-mimic hydrogels, including sacchachitin (SC), hyaluronic acid (HA) and chitosan (CS) and three composite hydrogels of combining SC either with aECM_HCl,25 (aECM_HCl/SC), HA (HA/SC) or CS (SC/CS) were prepared and evaluated for WS-1 cell viability and wound-healing effectiveness. Cell viability study confirmed that no hydrogel dressings possessed any toxicity at all concentrations examined and ECM_HCl, HA and ECM_HCl/SC at higher concentrations (>0.05%) induced statistically significant proliferation. Diabetic wound healing study and histological examinations revealed that ECM_HCl/SC hydrogel was observed to synergistically accelerate wound healing and ultimately stimulated the growth of hair follicles and sweat glands in the healing wound indicating the wound had healed as functional tissues. The results support the great potential of this newly produced ECM_HCl/SC composite hydrogel for healing and regeneration of diabetic wounds.

Hyaluronic Acid-Based Theranostic Nanomedicines for Targeted Cancer Therapy

Hyaluronic acid (HA) is a natural mucopolysaccharide and has many useful advantages, including biocompatibility, non-immunogenicity, chemical versatility, non-toxicity, biodegradability, and high hydrophilicity. Numerous tumor cells overexpress several receptors that have a high binding affinity for HA, while these receptors are poorly expressed in normal body cells. HA-based drug delivery carriers can offer improved solubility and stability of anticancer drugs in biological environments and allow for the targeting of cancer treatments. Based on these benefits, HA has been widely investigated as a promising material for developing the advanced clinical cancer therapies in various formulations, including nanoparticles, micelles, liposomes, and hydrogels, combined with other materials. We describe various approaches and findings showing the feasibility of improvement in theragnosis probes through the application of HA.

Injectable Hydrogels for Cancer Therapy over the Last Decade

The interest in injectable hydrogels for cancer treatment has been significantly growing over the last decade, due to the availability of a wide range of starting polymer structures with tailored features and high chemical versatility. Many research groups are working on the development of highly engineered injectable delivery vehicle systems suitable for combined chemo-and radio-therapy, as well as thermal and photo-thermal ablation, with the aim of finding out effective solutions to overcome the current obstacles of conventional therapeutic protocols. Within this work, we have reviewed and discussed the most recent injectable hydrogel systems, focusing on the structure and properties of the starting polymers, which are mainly classified into natural or synthetic sources. Moreover, mapping the research landscape of the fabrication strategies, the main outcome of each system is discussed in light of possible clinical applications.

Strategies for Hyaluronic Acid-Based Hydrogel Design in Drug Delivery

Hyaluronic acid (HA) is a natural, linear, endogenous polysaccharide that plays important physiological and biological roles in the human body. Nowadays, among biopolymers, HA is emerging as an appealing starting material for hydrogels design due to its biocompatibility, native biofunctionality, biodegradability, non-immunogenicity, and versatility. Since HA is not able to form gels alone, chemical modifications, covalent crosslinking, and gelling agents are always needed in order to obtain HA-based hydrogels. Therefore, in the last decade, different strategies for the design of physical and chemical HA hydrogels have been developed, such as click chemistry reactions, enzymatic and disulfide crosslinking, supramolecular assembly via inclusion complexation, and so on. HA-based hydrogels turn out to be versatile platforms, ranging from static to smart and stimuli-responsive systems, and for these reasons, they are widely investigated for biomedical applications like drug delivery, tissue engineering, regenerative medicine, cell therapy, and diagnostics. Furthermore, the overexpression of HA receptors on various tumor cells makes these platforms promising drug delivery systems for targeted cancer therapy. The aim of the present review is to highlight and discuss recent advances made in the last years on the design of chemical and physical HA-based hydrogels and their application for biomedical purposes, in particular, drug delivery. Notable attention is given to HA hydrogel-based drug delivery systems for targeted therapy of cancer and osteoarthritis.

Novel application of pluronic lecithin organogels (PLOs) for local delivery of synergistic combination of docetaxel and cisplatin to improve therapeutic efficacy against ovarian cancer

The synergistic combination of docetaxel (DTX) and cisplatin (CIS) by local drug delivery with a pluronic lecithin organogel (PLO) to facilitate high drug concentrations at tumor sites and less nonspecific distribution to normal organs is thought to be beneficial in chemotherapy. In this study, using Capryol-90 (C90) with the addition of lecithin as the oil phase was developed to carry DTX, which was then incorporated into a PLO-containing CIS to formulate a dual-drug injectable PLO for local delivery. An optimal PLO composite, P₁₃L_0.15O_1.5, composed of PF127:lecithin:C90 at a 13:0.15:1.5 weight ratio was obtained. The sol-gel transition temperature of P₁₃L_0.15O_1.5 was found to be 33 °C. Tumor inhibition studies illustrated that DTX/CIS-loaded P₁₃L_0.15O_1.5 could efficiently suppress tumor growth by both intratumoral and peritumoral injections in SKOV-3 xenograft mouse model. Pharmacokinetic studies showed that subcutaneous administration of P₁₃L_0.15O_1.5 was able to sustain the release of DTX and CIS leading to their slow absorption into the systemic circulation resulting in lower area under the plasma concentration curve at 0-72 h (AUC_0-72) and maximum concentration (C_max) values but longer half-life (T_1/2) and mean residence time (MRT) values. An in vivo biodistribution study showed lower DTX and CIS concentrations in organs compared to other treatment groups after IT administration of the dual drug-loaded P₁₃L_0.15O_1.5. It was concluded that the local co-delivery of DTX and CIS by PLOs may be a promising and effective platform for local anticancer drug delivery with minimal systemic toxicities.

Evaluation of micelles incorporated into thermosensitive hydrogels for intratumoral delivery and controlled release of docetaxel: A dual approach for in situ treatment of tumors

The in situ gelling hybrid hydrogel system has been reported to effectively concentrate chemotherapeutic drugs at the tumor site and sustain their release for a long period. DTX-micelles (docetaxel-loaded mixed micelles) are able to increase the solubility of DTX in water, and then a high drug loading rate of hydrogels can be achieved by encapsulating the docetaxel-loaded mixed micelles into the hydrogels. The thermosensitive nature of DTX-MM-hydrogels (thermosensitive hydrogels incorporated with docetaxel-loaded mixed micelles) can accelerate the formation of a depot of this drug-loaded system at the site of administration. Therefore, the hydrogels provide a much slower release compared with DTX-micelles and DTX-injection. An in vivo retention study has demonstrated that the DTX-MM-hydrogels can prolong the drug retention time and in vivo trials have shown that the DTX-MM-hydrogels have a higher antitumor efficacy and systemic safety. In conclusion, the DTX-MM-hydrogels prepared in this study have considerable potential as a drug delivery system, with higher tumor inhibition effects and are less toxic to normal tissues.

pH-responsive self-healing injectable hydrogel based on N-carboxyethyl chitosan for hepatocellular carcinoma therapy

Injectable hydrogels with pH-responsiveness and self-healing ability have great potential for anti-cancer drug delivery. Herein, we developed a series of polysaccharide-based self-healing hydrogels with pH-sensitivity as drug delivery vehicles for hepatocellular carcinoma therapy. The hydrogels were prepared by using N-carboxyethyl chitosan (CEC) synthesized via Michael reaction in aqueous solution and dibenzaldehyde-terminated poly(ethylene glycol) (PEGDA). Doxorubicin (Dox), as a model of water-soluble small molecule anti-cancer drug was encapsulated into the hydrogel in situ. Self-healing behavior of the hydrogels was investigated at microscopic and macroscopic levels, and the hydrogels showed rapid self-healing performance without any external stimulus owing to the dynamic covalent Schiff-base linkage between amine groups from CEC and benzaldehyde groups from PEGDA. The chemical structures, rheological property, in vitro gel degradation, morphology, gelation time and in vitro Dox release behavior from the hydrogels were characterized. Injectability was verified by in vitro injection and in vivo subcutaneous injection in a rat. pH-responsive behavior was verified by in vitro Dox release from hydrogels in PBS solutions with different pH values. Furthermore, the activity of Dox released from hydrogel matrix was evaluated by employing human hepatocellular liver carcinoma (HepG2). Cytotoxicity test of the hydrogels using L929 cells confirmed their good cytocompatibility. Together, these pH-responsive self-healing injectable hydrogels are excellent candidates as drug delivery vehicles for liver cancer treatment. STATEMENT OF SIGNIFICANCE: pH-responsive drug delivery system could release drug efficiently in targeted acid environment and minimalize the amount of drug release in normal physiological environment. pH-sensitive injectable hydrogels as smart anti-cancer drug delivery carriers show great potential application for cancer therapy. The hydrogels with self-healing property could prolong their lifetime during implantation and provide the advantage of minimally invasive surgery and high drug-loading ratio. This work reported the design of a series of pH-responsive self-healing injectable hydrogels based on N-carboxyethyl chitosan synthesized in aqueous solution and dibenzaldehyde-terminated poly(ethylene glycol) via a green approach, and demonstrated their potential as intelligent delivery vehicle of doxorubicin for hepatocellular carcinoma therapy via the pH-responsive nature of dynamic Schiff base.

Shear-responsive injectable supramolecular hydrogel releasing doxorubicin loaded micelles with pH-sensitivity for local tumor chemotherapy

In this study, glycol chitosan-Pluronic F127 conjugate (GC-PF127), produced by an amidation reaction between terminal-carboxylated PF127 and glycol chitosan (GC), was used to prepare doxorubicin (DOX)-loaded micelles. The DOX/GC-PF127 micelles produced at optimal conditions had sizes of about 150nm and pH-sensitive surface charges. DOX/GC-PF127 hydrogel formed after addition of α-cyclodextrin into DOX/GC-PF127 micelle solution. The hydrogel had good shear-responsive, injectable and rapid recovery properties. In vitro release experiment confirmed that the hydrogel could sustainedly release DOX/GC-PF127 micelles via the dissociation of the hydrogel. After peritumoral injection into H22 tumor-bearing mice, the hydrogel could greatly increase DOX accumulation in tumor tissue and synchronously avoid DOX accumulation in normal tissues including heart. At similar total DOX dose administrated, the tumors of free DOX treatment group grew slowly after thrice intravenous injections, the tumors of the micelle group did not grow after twice intravenous injections, and the tumors of the hydrogel group disappeared almost after once peritumoral injection. This study demonstrates that injectable DOX/GC-PF127 hydrogel, which can sustainedly release DOX-loaded micelles with tumor-targeting function, is a promising system for local tumor chemotherapy.

Rapid In Situ MRI Traceable Gel-forming Dual-drug Delivery for Synergistic Therapy of Brain Tumor

Preventing tumor recurrence after surgical resection of a brain tumor is a significant clinical challenge because current methods deliver chemotherapeutic agents in a rapid manner and are not effective against the residual tumor cells. To overcome this drawback, we report a simple method to prepare magnetic resonance imaging (MRI) traceable ultra-thermosensitive hydrogels with rapid gelation ability from aqueous solution within 4 s at 28 °C for hydrophilic (epirubicin, EPI) and hydrophobic (paclitaxel, PTX) drugs co-delivery with bovine serum albumin nanoparticles (BSA NPs) incorporation. The results showed the average survival of gliosarcoma-bearing (MBR 614 or U87) mice receiving BSA/PTX NPs incorporated hydrogel_Gd/EPI increased to 63 days or 69 days with no tumor recurrence observed. Our synergistic strategy presents a new approach to the development of a local drug delivery system for the prevention of brain tumor recurrence.

Development of a dual drug-loaded hydrogel delivery system for enhanced cancer therapy: in situ formation, degradation and synergistic antitumor efficiency

A stimuli-responsive, biodegradable, and dual drug-loaded hydrogel delivery system was formed in situ for combination drug therapy of cancer in vivo.

Layer-by-layer-coated lyotropic liquid crystalline nanoparticles for active tumor targeting of rapamycin

Aim: This work spotlights on fabrication of CD44-tropic, layer-by-layer (LbL) coated, liquid crystalline nanoparticles of rapamycin (Rap-LbL-LCNPs) to enhance its water solubility and enable its anticancer use. Methods: Rap-LCNPs were fabricated using hydrotrope method and then coated using LbL self-assembly technique. Results: LbL coating strategy successfully reduced monoolein-induced hemolysis and increased LCNPs serum stability. Lyophilized Rap-LbL-LCNPs were successfully sterilized using γ-radiations. In CD44-overexpressed MDA-MB-231 cells, Rap-LbL-LCNPs demonstrated superior cytotoxicity compared with the nontargeted formulation. Rap-LbL-LCNPs showed 3.35-fold increase in bioavailability compared with free drug. Rap-LbL-LCNPs significantly inhibited tumor growth, enhanced animal survival and reduced nephrotoxic and hyperglycemic effects of Rap. Conclusion: LbL coating strategy of Rap-LCNPs could serve as a promising approach that facilitates Rap use in cancer therapy.

Stimuli-sensitive thiolated hyaluronic acid based nanofibers: synthesis, preclinical safety and in vitro anti-HIV activity

AIM

To develop a seminal enzyme bioresponsive, mucoadhesive nanofibers (NFs) as safe and effective nanocarriers for the prevention of HIV vaginal transmission.

METHODS

A novel thiolated hyaluronic acid (HA-SH) polymer was synthesized to fabricate tenofovir (TFV)-loaded electrospun NFs (HA-SH-NFs) and characterized in vitro/in vivo.

RESULTS

A triggered drug release (87% w/w) from the engineered HA-SH-NFs (mean diameter ∼75 nm) occured within 1 h under the influence of seminal hyaluronidase enzyme. HA-SH-NFs were noncytotoxic, induced no damage on the C57BL/6 mice genital-tract and other organs. No significant CD45 cell-infiltration and changes in cytokines level in cervicovaginal tissues were observed. HA-SH-NFs significantly enhanced both TFV retention and bioavailability in vaginal tissue compared with the 1% TFV-gel. The anti-HIV activity of TFV (on pseudotyped virus followed by luciferase assay) was not adversely affected by the electrospinning process.

CONCLUSION

HA-SH-NFs developed in this study could potentially serve as a safe nanotemplate for topical intravaginal delivery of HIV/AIDS microbicides.

Recent trends on hydrogel based drug delivery systems for infectious diseases

Since centuries, the rapid spread and cure of infectious diseases have been a major concern to the progress and survival of humans. These diseases are a global burden and the prominent cause for worldwide deaths and disabilities. Nanomedicine has emerged as the most excellent tool to eradicate and halt their spread. Various nanoformulations (NFs) using advanced nanotechnology are in demand. Recently, hydrogel and nanogel based drug delivery devices have posed new prospects to simulate the natural intelligence of various biological systems. Owing to their unique porous interpenetrating network design, hydrophobic drug incorporation and stimulus sensitivity hydrogels owe excellent potential as targeted drug delivery systems. The present review is an attempt to highlight the recent trends of hydrogel based drug delivery systems for the delivery of therapeutic agents and diagnostics for major infectious diseases including acquired immune deficiency syndrome (AIDS), malaria, tuberculosis, influenza and ebola. Future prospects and challenges are also described.

Novel self-assembled tacrolimus nanoparticles cross-linking thermosensitive hydrogels for local rheumatoid arthritis therapy

The aim was to explore the potential application of novel self-assembled nanoparticles cross-linking thermosensitive hydrogels composed of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol (Soluplus) and tacrolimus (FK-506) for local therapy of rheumatoid arthritis (RA). The sol-gel transition temperature (T_sol-gel), gelation time, rheological behaviors, in vitro release, in vivo gelation and retention, and therapeutic efficacy against adjuvant-induced arthritis (AIA) rats were compared between the Soluplus hydrogels and widely studied poloxamer 407 (P407) delivery systems. In sol, the spherical and uniform FK506 loaded Soluplus nanoparticles (Soluplus-SNPs) were self-assembled with encapsulation efficiency of 99.5±1.5% and particle size of 73.9±2.9nm. The decreased T_sol-gel of Soluplus-SNPs hydrogels was associated with the addition of salts, elevation of pH and ionic strength. The optimal T_sol-gel of Soluplus-SNPs with concentrations of 10%-30% in phosphate buffer (50mM, pH 7.4) was from 37.4±0.1°C to 32.8±0.3°C and the gelation time was not greater than 2min. Soluplus-SNPs gelling systems showed lower viscosity and wider range concentrations in sol state at 25°C and stronger gel strength at 37°C than P407, which resulting in longer sustained release of FK506 but without burst-release in vitro, and longer retention time in the local injection site in vivo. The therapeutic efficacy to treat AIA rats was significantly enhanced from d10 to d17 after a single dose of FK506 loaded in 10% and 20% Soluplus-SNPs hydrogels. In conclusion, Soluplus-SNPs hydrogel is a potential sustainable delivery system for FK506 to treat RA locally.

Doxorubicin-induced co-assembling nanomedicines with temperature-sensitive acidic polymer and their in-situ-forming hydrogels for intratumoral administration

Doxorubicin (DOX)-induced co-assembling nanomedicines (D-PNAx) with temperature-sensitive PNAx triblock polymers have been developed for regional chemotherapy against liver cancer via intratumoral administration in the present work. Owing to the formation of insoluble DOX carboxylate, D-PNAx nanomedicines showed high drug-loading and entrapment efficacy via a simple mixing of doxorubicin hydrochloride and PNAx polymers. The sustained releasing profile of D-PNA100 nanomedicines indicated that only 9.4% of DOX was released within 1day, and 60% was released during 10days. Based on DOX-induced co-assembling behavior and their temperature sensitive in-situ-forming hydrogels, D-PNA100 nanomedicines showed excellent antitumor activity against H22 tumor using intratumoral administration. In contrast to that by free DOX solution (1.13±0.04 times at 9days) and blank PNA100 (2.11±0.34 times), the tumor volume treated by D-PNA100 had been falling to only 0.77±0.13 times of original tumor volume throughout the experimental period. In vivo biodistribution of DOX indicated that D-PNA100 nanomedicines exhibited much stronger DOX retention in tumor tissues than free DOX solution via intratumoral injection. D-PNA100 nanomedicines were hopeful to be developed as new temperature sensitive in-situ-forming hydrogels via i.t. injection for regional chemotherapy.

Hyaluronic acid for anticancer drug and nucleic acid delivery

Hyaluronic acid (HA) is widely used in anticancer drug delivery, since it is biocompatible, biodegradable, non-toxic, and non-immunogenic; moreover, HA receptors are overexpressed on many tumor cells. Exploiting this ligand-receptor interaction, the use of HA is now a rapidly-growing platform for targeting CD44-overexpressing cells, to improve anticancer therapies. The rationale underlying approaches, chemical strategies, and recent advances in the use of HA to design drug carriers for delivering anticancer agents, are reviewed. Comprehensive descriptions are given of HA-based drug conjugates, particulate carriers (micelles, liposomes, nanoparticles, microparticles), inorganic nanostructures, and hydrogels, with particular emphasis on reports of preclinical/clinical results.