Carboxymethyl-hexanoyl Chitosan Research Articles

Carboxymethyl-hexanoyl chitosan: A promising candidate for hydrophobic and hydrophilic drug delivery

Biodegradable polymers are versatile materials that are used in a plethora of biomedical applications owing to their biocompatible nature, degradability, non-toxicity, and low cost. Among the available biodegradable polymers, chitosan is found highly utilized in various pharmaceutical applications. Chitosan is soluble in weak acidic medium, which hinders further utility in higher concentrations for biological applications. However, derivatives of chitosan could be explored for biomedical applications by considering their aqueous solubility followed by hydrophobic and hydrophilic drug encapsulation efficiency. One among them, carboxymethyl-hexanoyl chitosan (CHC) has demonstrated promising footprints in ocular drug delivery, cancer therapeutics, insulin delivery, tissue engineering, multimodal imaging, antimicrobial activity, and wound healing applications. Furthermore, biocompatibility, water retention and uptake ability, and biodegradability are attributed to the presence of both amino and carboxylic functional groups present in CHC. In the present review, we have given a consolidated overview of CHC-based systems used so far in biomedical applications including global trends and future perspective. We believe that the review will help to understand CHC-based systems and the need for further innovations in the biomedical sciences.

Anti-fouling and anti-coagulation capabilities of PEDOT-biopolymer coating by in-situ electrochemical copolymerization

In this study, 3,4-ethylenedioxythiophene (EDOT), polystyrene sulfonate (PSS), chondroitin sulfate (CHS), and carboxymethyl-hexanoyl chitosan (CHC) nanohybrids were coated on nitrogen plasma pre-treated SUS316L stainless steel using in-situ electrochemically copolymerization. The negatively charged PSS, CHS, and CHC were used to repel the negatively charged proteins, platelets, and cell walls of bacteria (E. coli) to achieve anti-fouling and anti-clotting capabilities. The anti-fouling capabilities of the poly-3,4-ethylenedioxythiophene (PEDOT) derivative coatings had the following order: PEDOT/CHC/CHS > PEDOT/CHS > PEDOT/CHS/PSS > PEDOT/PSS > pristine SUS316L. In particular, with the addition of CHC, the PEDOT/CHC/CHS coating could decrease the adhesion of platelets and bacteria using the functional group (-COOH) of CHC. The blood clotting time (activated partial thromboplastin time) of the PEDOT/CHC/CHS substrates was prolonged to 48 s, compared to the 32 s required for the pristine SUS316L stainless steel, showing the good hemocompatibility. Furthermore, cytotoxicity tests showed that PEDOT and its derivatives exhibited very good biocompatibility. Thus, they could potentially be applied in anti-clotting, anti-fouling, and anti-bacterial biomedical devices such as cardiovascular stents.

Thermo-reversible injectable hydrogel composing of pluronic F127 and carboxymethyl hexanoyl chitosan for cell-encapsulation

This study demonstrated a novel injectable-thermoreversible hydrogel scaffold composing of PLuronic F127, carboxymethyl hexanoyl chitosan (CA) and glyoxal (Gx) for encapsulating human osteosarcoma MG-63 cells. The hydrogel was prepared by simply mixing CA, F127 and Gx. In so doing, this system exhibited short gelation time and higher gelation temperature. In addition, this hydrogel exhibited thermo-reversibility, that is, the hydrogel can liquefy at room temperature and revert to gel state at body temperature. The encapsulated cells in this hydrogel proliferated more than 400% in the 5-day incubation. Based on these results, these F127/CA/Gx hydrogels can be used to encapsulate cells for tissue engineering applications.

A new and efficient carboxymethyl-hexanoyl chitosan/dodecyl sulfate nanocarrier for a pyrazoline with antileukemic activity

We describe herein a chitosan nanocarrier for drug delivery applications obtained through the self-assembly of carboxymethyl-hexanoyl chitosan and dodecyl sulfate (CHC-SDS). Nanocapsules with spherical morphology were obtained in phosphate buffer at pH 7.4. These CHC-SDS nanocapsules showed no toxicity toward Jurkat cells (acute lymphoblastic leukemia) and were used to encapsulate a new pyrazoline (H3TM04) with antileukemia activity. The samples were characterized by dynamic light scattering (DLS) and Laser Doppler Micro-Electrophoresis. The encapsulation efficiency was higher than 96% (293.6 μg mL-1) and the H3TM04-loaded nanocapsules (CHC-SDS-H) had a negative surface charge (-29.8 ± 0.7 mV) and hydrodynamic radius of around 84 nm. For the first time, CHC-SDS-H were formed and the antitumoral cancer activity was proved. The in vitro assays showed the controlled release of H3TM04 from the CHC-SDS-H nanocapsules in phosphate buffer pH 7.4. The H3TM04 release data were described by the power law model, indicating that H3TM04 delivery occurred via an erosion mechanism. The cytotoxicity assays with Jurkat and K-562 cells (acute myeloid leukemia) demonstrated that the CHC-SDS-H nanocapsule decreases the half maximal inhibitory concentration (IC50). The study showed that CHC-SDS nanocapsules represent a promising nanocarrier for pyrazoline derivates that could be applied in leukemia therapy.

Preparation of Amphiphilic Chitosan–Graphene Oxide–Cellulose Nanocrystalline Composite Hydrogels and Their Biocompatibility and Antibacterial Properties

Environmental-friendly nanocomposite hydrogels of carboxymethyl-hexanoyl chitosan (CHC), graphene oxide (GO) and cellulose nanocrystals (CNCs) were combined to produce a bio-hydrogel with great biocompatibility and antibacterial ability. The size of the GO nanosheets was about 200–500 nm, and the CNCs had a length of 100–200 nm and a width of 10–20 nm, as shown by transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) was utilized for the analysis of the oxygen functional groups of GO. The homogeneous dispersion of the CHC/GO/CNC nanocomposite hydrogel showed significantly higher water absorption capacity and water retention capability. In addition, inhibition of a variety of microorganisms (gram-negative and gram-positive bacteria and fungi) by the introduction of the CHC/GO/CNC nanocomposite hydrogel demonstrated that there is a great opportunity to use it in the bio-medical field, such as for plastic masks and wound dressings.

Self-assembled amphiphilic chitosan: A time-dependent nanostructural evolution and associated drug encapsulation/elution mechanism

This investigation reports the nanostructural evolution and associated encapsulation and elution of a hydrophobic drug, demethoxycurcumin (DMC), as a molecular probe, with the carboxymethyl-hexanoyl chitosan (CHC), which has been a technically interesting amphiphilic chitosan-based polymer successfully developed in this lab for years. The self-assembly nature of the CHC in neutral aqueous solutions allowed efficient encapsulation of various drugs without deteriorating or changing drugs’ activity. However, its self-assembly behavior associated with nanostructural stability or variation, in terms of residence time in aqueous solution has not been well characterized and how the CHC nanostructure may be altered upon entrapping a drug, followed releasing out of the nanostructure. In this study, the CHC/DMC assembled model was used to evaluate entrapping efficiency, CHC-DMC interaction, and nanostructural variation while the drug being encapsulated and released from the CHC nanoparticles. Experimental outcomes showed a fractal transition between nanoparticulate and short fiber-like network evolution of the CHC as time elapsed, with the presence or absence of the DMC probe. This entrapment of DMC is relatively efficient upon CHC assembly and the associated DMC arrangement inside the helical CHC macromolecule gave largely increasing space over the resulting CHC/DMC assembly. Its excellent colloidal and nanostructural stability over a reasonably long period of time in testing environment suggests that this CHC/DMC assembly not only provides a crucial advantage for drug delivery application but also considers as a nanostructural model for better understanding of the mechanism upon drug encapsulation and elution which may be applicable to alternative amphiphilic polysaccharide-based macromolecules.

Aggregation behavior of self-assembled nanoparticles made from carboxymethyl-hexanoyl chitosan and sodium dodecyl sulphate surfactant in water

Biopolymers can be used to produce nano-objects in solution and they are generally of low cost and biocompatible. However, they commonly have low kinetic stability and form aggregates with a broad particle size distribution, characteristics that hinder their use in drug delivery systems. Herein, we report the thermodynamics and mechanisms underlying the formation of nanostructures through the self-assembly of carboxymethyl-hexanoyl chitosan (ONCHC) and the effect of the presence of the surfactant sodium dodecyl sulfate (SDS). The pre- and post-aggregation regimes were monitored using several techniques and indicated that self-assembly is thermodynamically favorable. The presence of SDS decreased the hydrodynamic radius and surface charge of the SDS-ONCHC nanoaggregates and increased the kinetic stability in aqueous solution over a period of 150 days. The SDS-ONCHC interaction is driven mainly by a hydrophobic effect and the addition of SDS increases the number and strength of the hydrophobic domains, where the integral enthalpy change for the aggregate formation is −2.11 kJ mol−1.

A novel injectable in situ forming gel based on carboxymethyl hexanoyl chitosan/hyaluronic acid polymer blending for sustained release of berberine

An in situ forming gel based on simply blending carboxymethyl hexanoyl chitosan (CHC) with low molecular weight hyaluronic acid (LMW HA) was developed, without needing cross-linking, photopolymerization or thermal treatments. The CHC/LMW HA blends formed nanoparticles and then rapidly transformed into supermolecular hydrogels under stirring. The gel formation mechanism was examined by Förster resonance energy transfer (FRET). The gels were injectable, cytocompatible and biodegradable, and showed shape-persistent behavior and adhesive property. Berberine, an anti-apoptotic and anti-arthritis naturally occurring compound, was encapsulated within the CHC/LMW HA gels. The gels demonstrated a pH-responsive characteristic which were able to release berberine in a sustained manner at pH 6.0 (simulating inflamed arthritic articular cartilage) and the degradation rates were accelerated at pH 7.4 (simulating healed normal tissue). The berberine-loaded gels effectively protected chondrocytes against sodium nitroprusside-induced apoptosis. The gels may be potentially useful as an injectable system for intra-articular drug delivery and cartilage tissue engineering.

Assessment of antagonistic activity of free and encapsulated Bifidobacterium bifidum against Salmonella

AbstractThe objective of this study was to evaluate the stability of Bifidobacterium bifidum in the yoghurt with and without encapsulation. The B. bifidum was encapsulated with 6% sodium alginate concentration (SAC) and 0.8% Carboxymethyl‐Hexanoyl chitosan (CHC) as a single coating and then double‐coated with whey protein concentrate (WPC). After that, yoghurt was prepared with the addition of free and encapsulated probiotic (B. bifidum) along with the starter cultures and studied weekly up to 28th day of storage. Organoleptic analysis also shows higher score in encapsulated probiotic bacteria rather than free. The viable count of probiotic and yoghurt cultures was affected significantly (p < .01) during refrigerated storage of yoghurt and their survivability remained higher (8.81 ± 0.35 to 5.39 ± 0.58 log cfu/ml) in double‐coated encapsulated yoghurt. Encapsulated cells of probiotic culture have shown minimum zone of inhibition compared with free cells, and antibiotic (gentamicin) has shown maximum resistance against Salmonella.Practical applicationsThe present study concludes that probiotics can be used against foodborne pathogens but antibiotic has shown more resistant as compared to probiotic. The most efficient and significant technology for probiotics preservation is encapsulation against unfavorable environmental conditions. So, to improve the physical stability of alginate gels, chitosan coating material enhanced the survival of encapsulated probiotic in the yoghurt. The results of this study can be used at industrial level to claim health benefits of encapsulated probiotics for consumers.

A new type of gadodiamide-conjugated amphiphilic chitosan nanoparticle and its use for MR imaging with significantly enhanced contrastability

Magnetic resonance imaging (MRI) has been one of the most frequently-used diagnostic tools with high dimensional precision and positioning accuracy in clinical practices. To achieve contrast enhancement, utilization of high-efficient MR imaging contrast agents becomes a prime consideration and is indispensably reinforced the diagnosis precision, especially for the emerging precision medicine. Gadolinium (Gd)-based complexes has been widely used in current clinical MRI operations, however, numerous side effects were reported and highlighted in clinic. Those drawbacks render specific unmet needs to be clinically and technically improved with a new version of Gd-based compound. Here we report a newly-synthesized amphiphilic Gadodiamide-conjugated carboxymethyl-hexanoyl chitosan (termed as CHC-Gd) hybrid. The gadodiamide was selected is due to its smallest molecular size among other Gd-based complexes reported in literature, which assumed to give least influence on the resulting physicochemical properties such as colloidal stability, nanostructural evolution, and cytocompability, particularly self-assembly capability, of the resulting hybrid upon practical uses. Experimental outcomes showed a successful synthesis of the CHC-Gd hybrid using a one-pot synthesis protocol, where the gadodiamide complexes were covalently attached to the carboxyl groups along the CHC backbone. Self-assembly behavior can be observed to form a sphere-like nanoparticle of 100–200 nm in size as of amphiphilic native CHC macromolecule. Experimental outcomes indicated a largely improved cytocompatibility of the hybrid, compared with free Gd, suggesting the Gd+3 ions were well stabilized in the CHC nanostructure. Excellent contrastability in-vitro and in particular in vivo were measured, where for in-vivo test, a 10-40-folded reduction in dosage, compared with clinical Gd dose, was used and demonstrated a comparative-to-better imaging resolution and brightness. Therefore, from this preliminary investigation, a potential translation to clinical practice through the use of newly-synthesized amphiphilic CHC-Gd hybrid appears to be relatively promising.

Carboxymethyl-hexanoyl Chitosan Nanodroplets for Ultrasonic Imaging and Drug Delivery to Tumor.

Although a great many strategies have been proposed for tumor-targeted chemotherapy, current delivery methods of anticancer drugs present limited success with inevitable systemic toxicity. The aim of this study was to develop a new kind of theranostic carrier for targeted tumor therapy. Prior to prepare CHC-PFP-DOX, carboxymethyl-hexanoyl chitosan (CHC) was synthesized by acylation of carboxymethyl chitosan. To develop CHC-PFP, perfluoropentane (PFP), an ultrasound gas precursor, was simultaneously encapsulated into the hydrophobic inner cores of pre-formulated CHC micelle in aqueous phase via using the oil in water (O/W) emulsion method. The size distribution and surface charges of these nanodroplets were measured and the morphology was observed by transmission electron microscopy (TEM). For ultrasound imaging application, in vitro model was established to evaluate the imaging of CHC-PFP-DOX under different concentration and mechanical index. After that, the anti-tumor effect of ultrasound combined with CHC-PFPDOX on ovarian cancer cells was investigated. The resulting CHC-PFP-DOX had a nano-sized particle structure, with hydrophobic anticancer DOX/PFP inner cores and a hydrophilic carboxymethyl chitosan polymer outer shell. The favorable nano-scaled size offers the potential to extravagate from veins and accumulate in tumor tissues via enhanced permeation and retention (EPR) effect. Additionally, CHC-PFP-DOX showed the ability to serve as ultrasound imaging agent at body temperature. Notably, it exhibited an ultrasound-triggered drug release profile through the external ultrasound irradiation. Further study demonstrated that ultrasound combined with CHC-PFP-DOX can improve the killing effect of chemotherapy for tumor. CHC-PFP-DOX holds great promise in simultaneous cancer-targeting ultrasound imaging and ultrasound- mediated delivery for cancer chemotherapy.

Inhibition of Periodontitis Induction Using a Stimuli-Responsive Hydrogel Carrying Naringin.

Developing a drug carrier with favorable handling characteristics that can respond to environmental changes after inflammation, such as pH changes, may be beneficial for treating periodontitis. This study aims to investigate the preclinical feasibility of using naringin, a naturally derived polymethoxylated flavonoid compound with anti-inflammatory properties, to inhibit periodontitis induction via a thermogelling and pH-responsive injectable hydrogel. The hydrogel was made of amphipathic carboxymethyl-hexanoyl chitosan (CHC), β-glycerol phosphate (β-GP), and glycerol. Thermogelling and pH-responsive characteristics of the hydrogel, as well as cell viability after treatment with the hydrogel containing naringin, were evaluated in vitro. Hydrogel was subgingivally delivered when experimental periodontitis was induced in vivo, and therapeutic effect was evaluated with microcomputed tomography imaging, histology, and expression of inflammation-associated genes, including toll-like receptor (TLR)2, the receptor for advanced glycation end products (RAGE), myeloid differentiation primary response gene-88, and tumor necrosis factor (TNF)-α. The hydrogel was consistently fluidic at 4°C but rapidly gelled at 37°C. Release of naringin was faster at pH 5.5 to 6.5, and viability was significantly promoted by treatment with 0.85% naringin. Naringin-carrying CHC-β-GP-glycerol hydrogel sites showed significantly reduced periodontal bone loss (P <0.05) and inflammatory infiltration (P <0.01) as well as significantly downregulated TLR2 (P <0.05), RAGE (P <0.01), and TNF-α (P <0.05) relative to the sites with experimental periodontitis alone. Naringin-carrying CHC-β-GP-glycerol colloidal hydrogel can be used to inhibit induction of experimental periodontitis with favorable handling and inflammation-responsive characteristics.

Dual drug-loaded biofunctionalized amphiphilic chitosan nanoparticles: Enhanced synergy between cisplatin and demethoxycurcumin against multidrug-resistant stem-like lung cancer cells

Lung cancer kills more humans than any other cancer and multidrug resistance (MDR) in cancer stem-like cells (CSC) is emerging as a reason for failed treatments. One concept that addresses this root cause of treatment failure is the utilization of nanoparticles to simultaneously deliver dual drugs to cancer cells with synergistic performance, easy to envision — hard to achieve. (1) It is challenging to simultaneously load drugs of highly different physicochemical properties into one nanoparticle, (2) release kinetics may differ between drugs and (3) general requirements for biomedical nanoparticles apply. Here self-assembled nanoparticles of amphiphilic carboxymethyl-hexanoyl chitosan (CHC) were shown to present nano-microenvironments enabling simultaneous loading of hydrophilic and hydrophobic drugs. This was expanded into a dual-drug nano-delivery system to treat lung CSC. CHC nanoparticles were loaded/chemically modified with the anticancer drug cisplatin and the MDR-suppressing Chinese herbal extract demethoxycurcumin, followed by biofunctionalization with CD133 antibody for enhanced uptake by lung CSC, all in a feasible one-pot preparation. The nanoparticles were characterized with regard to chemistry, size, zeta potential and drug loading/release. Biofunctionalized and non-functionalized nanoparticles were investigated for uptake by lung CSC. Subsequently the cytotoxicity of single and dual drugs, free in solution or in nanoparticles, was evaluated against lung CSC at different doses. From the dose response at different concentrations the degree of synergy was determined through Chou-Talalay’s Plot. The biofunctionalized nanoparticles promoted synergistic effects between the drugs and were highly effective against MDR lung CSC. The efficacy and feasible one-pot preparation suggests preclinical studies using relevant disease models to be justified.

Design and optimization of a nanoprobe comprising amphiphilic chitosan colloids and Au-nanorods: Sensitive detection of human serum albumin in simulated urine

Metallic nanoparticles have been utilized as analytical tools to detect a wide range of organic analytes. In most reports, gold (Au)-based nanosensors have been modified with ligands to introduce selectivity towards a specific target molecule. However, in a recent study a new concept was presented where bare Au-nanorods on self-assembled carboxymethyl-hexanoyl chitosan (CHC) nanocarriers achieved sensitive and selective detection of human serum albumin (HSA) after manipulation of the solution pH. Here this concept was further advanced through optimization of the ratio between Au-nanorods and CHC nanocarriers to create a nanotechnology-based sensor (termed CHC-AuNR nanoprobe) with an outstanding lower detection limit (LDL) for HSA. The CHC-AuNR nanoprobe was evaluated in simulated urine solution and a LDL as low as 1.5pM was achieved at an estimated AuNR/CHC ratio of 2. Elemental mapping and protein adsorption kinetics over three orders of magnitude in HSA concentration confirmed accumulation of HSA on the nanorods and revealed the adsorption to be completed within 15min for all investigated concentrations. The results suggest that the CHC-AuNR nanoprobe has potential to be utilized for cost-effective detection of analytes in complex liquids.

Evaluation of hydrogel composing of Pluronic F127 and carboxymethyl hexanoyl chitosan as injectable scaffold for tissue engineering applications

This study demonstrated a novel hydrogel system composing of Pluronic F127, carboxymethyl hexanoyl chitosan (CA) and glutaraldehyde (GA) for encapsulating fibroblasts (L-929). The thermal behavior of the hydrogel was evaluated using TGA, the swelling behavior of the hydrogel was evaluated in Dulbecco's Modified Eagle's medium (DMEM), and the mechanical properties were determined through dynamic mechanical analysis. Cells were encapsulated by simple mixing, and the viability of encapsulated cells was determined using alamar blue cell viability assay and the cells morphology was examined using fluorescent imaging. The results indicated that the Tgel of this system was around 30°C, where sol-gel transformation occurred within 90s. Although the addition of CA and GA reduced the shear moduli slightly, the F127/CA/GA gel was able to remain in gelling state in the medium for more than 1 month. In vitro cell culture study revealed that F-127/CA/GA hydrogels were non-cytotoxic. Moreover, the viability of encapsulated L929 was 106% after incubation for 5 days. Based on these results, these F127/CA/GA hydrogels can be used to encapsulate cells for tissue engineering applications.

Growth factors-loaded calcium phosphate/polymer hybrid coating with sequential release behavior prepared via electrochemical deposition method

Abstract In this study, the dicalcium phosphate dehydrate (DCPD)/carboxymethyl hexanoyl chitosan (CHC) hybrid coating layer with sequential release of BMP-2 and TGF-β1 was deposited onto Ti6Al4V substrate by electrochemical co-precipitation method. Different concentrations of amphiphatic chitosan derivative (carboxymethyl hexanoyl chitosan, CHC), BMP-2 and TGF-β1-loaded PLA microspheres (PLA/TGF-β1 MSs) were co-precipitated with the precursor of DCPD. The resulting DCPD/CHC hybrid coating incorporated with BMP-2 and PLA/TGF-β1 MSs was designed for improving the osteoconductive and osteoinductive functionalities of Ti6Al4V. FTIR spectroscopy and X-ray diffraction were used to characterize these hybrid coatings. The drug release profile, MC3T3-E1 cell proliferation and alkaline phosphatase activity were used to investigate the functionality of these hybrid coatings. It was found that the incorporation of CHC could be used as a mean to manipulate the release behavior of growth factor from the DCPD/CHC hybrid coating. In addition, the BMP-2- and PLA/TGF-β1 MSs-incorporated DCPD/CHC hybrid coating exhibited a sequential release of BMP-2 and TGF-β1 during the first and second two weeks, respectively. Importantly, the DCPD/CHC hybrid coating immersed in simulated body fluid gradually transformed to hydroxyapatite phase. Hence, the BMP-2 and PLA/TGF-β1 MSs-incorporated DCPD/CHC hybrid coating exhibited the best cell viability and the highest ALP activity after 14 days. The biocompatible hybrid coating with sequential release functionality proposed in the present study can enhance the osseointegration process and possess promising potential for clinical applications in bone implants and tissue engineering.

Injectable insulin-lysozyme-loaded nanogels with enzymatically-controlled degradation and release for basal insulin treatment: In vitro characterization and in vivo observation

Diabetes is a common global disease that causes immense suffering for individuals and huge costs for the health care system. To minimize complications such as organ degeneration, diabetic patients are required to undergo treatments to maintain the blood glucose level in the normal range, ideally mimicking normal insulin secretion. The normal physiological insulin secretion pattern in healthy individuals consists of a base (basal) level through the day and increased secretion after meals (bolus insulin). Thus effective treatments may combine long acting, low-level insulin therapy with boosts of short acting insulin and/or oral agents. To achieve long term management of basal insulin level, an injectable insulin-loaded gel composed of self-assembled nanoparticles from carboxymethyl-hexanoyl chitosan (CHC) and integrated lysozyme for controlled biodegradation and insulin release was developed. In vitro characterizations and evaluations confirmed that lysozyme was active on CHC and that the amount of lysozyme in a CHC hydrogel determined the degradation and insulin release rate. The degradation products were found to be highly cytocompatible using a cell assay. In vivo evaluation of the system in a diabetic mouse model revealed that the fasted blood glucose level could be maintained in the normal range for 10days with a single injection of insulin-loaded CHC-lysozyme gel. The insulin-loaded CHC-lysozyme gels clearly show promise for use as a novel injectable long-acting insulin delivery system, with potential to manage the basal insulin level for many days with a single injection.

Enhanced antioxidant capacity of dental pulp-derived iPSC-differentiated hepatocytes and liver regeneration by injectable HGF-releasing hydrogel in fulminant hepatic failure.

Acute hepatic failure (AHF) is a severe liver injury leading to sustained damage and complications. Induced pluripotent stem cells (iPSCs) may be an alternative option for the treatment of AHF. In this study, we reprogrammed human dental pulp-derived fibroblasts into iPSCs, which exhibited pluripotency and the capacity to differentiate into tridermal lineages, including hepatocyte-like cells (iPSC-Heps). These iPSC-Heps resembled human embryonic stem cell-derived hepatocyte-like cells in gene signature and hepatic markers/functions. To improve iPSC-Heps engraftment, we next developed an injectable carboxymethyl-hexanoyl chitosan hydrogel (CHC) with sustained hepatocyte growth factor (HGF) release (HGF-CHC) and investigated the hepatoprotective activity of HGF-CHC-delivered iPSC-Heps in vitro and in an immunocompromised AHF mouse model induced by thioacetamide (TAA). Intrahepatic delivery of HGF-CHC-iPSC-Heps reduced the TAA-induced hepatic necrotic area and rescued liver function and recipient viability. Compared with PBS-delivered iPSC-Heps, the HGF-CHC-delivered iPSC-Heps exhibited higher antioxidant and antiapoptotic activities that reduced hepatic necrotic area. Importantly, these HGF-CHC-mediated responses could be abolished by administering anti-HGF neutralizing antibodies. In conclusion, our findings demonstrated that HGF mediated the enhancement of iPSC-Hep antioxidant/antiapoptotic capacities and hepatoprotection and that HGF-CHC is as an excellent vehicle for iPSC-Hep engraftment in iPSC-based therapy against AHF.

Synergistic effects of carboxymethyl-hexanoyl chitosan, cationic polyurethane-short branch PEI in miR122 gene delivery: Accelerated differentiation of iPSCs into mature hepatocyte-like cells and improved stem cell therapy in a hepatic failure model

MicroRNA122 (miR122), a liver-specific microRNA, plays critical roles in homeostatic regulation and hepatic-specific differentiation. Induced pluripotent stem cells (iPSCs) have promising potential in regenerative medicine, but it remains unknown whether non-viral vector-mediated miR122 delivery can enhance the differentiation of iPSCs into hepatocyte-like cells (iPSC-Heps) and rescue thioacetamide-induced acute hepatic failure (AHF) in vivo. In this study, we demonstrated that embedment of miR122 complexed with polyurethane-graft-short-branch polyethylenimine copolymer (PU-PEI) in nanostructured amphiphatic carboxymethyl–hexanoyl chitosan (CHC) led to dramatically enhanced miR122 delivery into human dental pulp-derived iPSCs (DP-iPSCs) and facilitated these DP-iPSCs to differentiate into iPSC-Heps (miR122-iPSC-Heps) with mature hepatocyte functions. Microarray and bioinformatics analysis further indicated that CHC/PU-PEI-miR122 promoted the gene-signature pattern of DP-iPSCs to shift into a liver-specific pattern. Furthermore, intrahepatic delivery of miR122-iPSC-Heps, but not miR-Scr-iPSC-Heps, improved liver functions and rescued recipient survival, and CHC-mediated delivery showed a better efficacy than that using phosphate buffered saline as a delivery vehicle. In addition, these transplanted miR122-iPSC-Heps remained viable and could produce circulatory albumin for 4months. Taken together, our findings demonstrate that non-viral delivery of miR122 shortens the time of iPSC differentiation into hepatocytes and the delivery of miR122-iPSC-Heps using CHC as a vehicle exhibited promising hepatoprotective efficacy in vivo. miR122-iPSC-Heps may represent a feasible cell source and provide an efficient and alternative strategy for hepatic regeneration in AHF.

A novel bubble-forming material for preparing hydrophobic-agent-loaded bubbles with theranostic functionality

In the present study, a new bubble-forming material (carboxymethyl hexanoyl chitosan, CHC), together with superparamagnetic iron oxide (SPIO) nanoparticles, was employed to prepare image-guided bubbles for efficiently encapsulating and delivering hydrophobic agents to kill tumor cells. The results showed that CHC could be used for preparing not only micronized bubbles (CHC/SPIO MBs) to exhibit ultrasound imaging functionality but also nanosized bubbles (CHC/SPIO NBs) to exhibit magnetic resonance T2 image contrast. It was found that the amounts of SPIO nanoparticles and hexane during preparation process were the key factors to obtaining CHC/SPIO NBs. Most importantly, under in vitro cell culture conditions with the same amount of camptothecin (CPT) and therapeutic sonication, CPT-loaded CHC/SPIO NBs demonstrated more significant transcellular delivery and cytotoxicity than free CPT. Subsequently, an intratumoral injection was proposed for the in vivo administration of hydrophobic-agent-loaded CHC/SPIO NBs. After injection, the distribution of a hydrophobic dye (DiR, an agent with near-infrared (NIR) fluorescence used as a model drug) released from the CHC/SPIO NBs was tracked by an NIR imaging technique. A significant tumor-specific accumulation was observed in the mouse that received the DiR-loaded CHC/SPIO NBs; the same was not observed in the mouse that received the free dye (without incorporating with CHC/SPIO NBs). It is expected, in the future, both the dose of the therapeutic agent administered and its side effects can be significantly lowered by using novel CHC/SPIO NBs together with local delivery (intratumoral injection), targeted imaging and enhanced cellular uptake of the drug.