Coordinated ASBT and EGFR Mechanisms for Optimized Liraglutide Nanoformulation Absorption in the GI Tract.

Background: For maintenance therapy in type 2 diabetes, glucagon-like peptide-1 agonist (GLP-1A), which exhibits low cardiovascular risk and high efficacy, is a promising peptide therapeutic. However, developing an oral GLP-1A presents challenges due to the analog's poor cellular permeability and gastrointestinal (GI) stability. Methods: To mitigate such limitations, an oral nanoformulation of liraglutide (LG) was designed and achieved by combining LG with bile acid derivatives using the nanoprecipitation method. This strategy allowed the bile acid moieties to localize at the nanoparticle surface, enhancing the binding affinity for apical sodium-dependent bile acid transporter (ASBT) and improving GI stability. The in vitro characteristics, cellular permeability, and absorption mechanisms of the LG nanoformulation (LG/TD-NF) were thoroughly investigated. Furthermore, the in vivo oral absorption in rats and the glucose-lowering effects in a diabetic (db/db) mouse model were evaluated. Results: The LG/TD-NF produced neutral nanoparticles with a diameter of 58.7 ± 4.3 nm and a zeta potential of 4.9 ± 0.4 mV. Notably, when exposed to simulated gastric fluid, 65.7 ± 3.6% of the LG/TD-NF remained stable over 120 min, while free LG was fully degraded. Relative to unformulated LG, the Caco-2 cellular permeability of the nanoformulation improved, measuring 10.9 ± 2.1 (× 10-6 cm/s). The absorption mechanism prominently featured endocytosis simultaneously mediated by both ASBT and epidermal growth factor receptor (EGFR). The oral bioavailability of the LG/TD-NF was determined to be 3.62% at a dosage of 10 mg/kg, which is 45.3 times greater than that of free LG. In a diabetes model, LG/TD-NF at 10 mg/kg/day exhibited commendable glucose sensitivity and reduced HbA1c levels by 4.13% within 28 days, similar to that of subcutaneously administered LG at a dosage of 0.1 mg/kg/day. Conclusion: The oral LG/TD-NF promotes ASBT/EGFR-mediated transcytosis and assures cellular permeability within the GI tract. This method holds promise for the development of oral GLP-1A peptides as an alternative to injections, potentially enhancing patient adherence to maintenance therapy.

Design of chimeric GLP-1A using oligomeric bile acids to utilize transporter-mediated endocytosis for oral delivery.

BACKGROUND: Despite the effectiveness of glucagon-like peptide-1 agonist (GLP-1A) in the treatment of diabetes, its large molecular weight and high hydrophilicity result in poor cellular permeability, thus limiting its oral bioavailability. To address this, we developed a chimeric GLP-1A that targets transporter-mediated endocytosis to enhance cellular permeability to GLP-1A by utilizing the transporters available in the intestine, particularly the apical sodium-dependent bile acid transporter (ASBT). METHODS: In silico molecular docking and molecular dynamics simulations were used to investigate the binding interactions of mono-, bis-, and tetra-deoxycholic acid (DOCA) (monoDOCA, bisDOCA, and tetraDOCA) with ASBT. After synthesizing the chimeric GLP-1A-conjugated oligomeric DOCAs (mD-G1A, bD-G1A, and tD-G1A) using a maleimide reaction, in vitro cellular permeability and insulinotropic effects were assessed. Furthermore, in vivo oral absorption in rats and hypoglycemic effect on diabetic db/db mice model were evaluated. RESULTS: In silico results showed that tetraDOCA had the lowest interaction energy, indicating high binding affinity to ASBT. Insulinotropic effects of GLP-1A-conjugated oligomeric DOCAs were not different from those of GLP-1A-Cys or exenatide. Moreover, bD-G1A and tD-G1A exhibited improved in vitro Caco-2 cellular permeability and showed higher in vivo bioavailability (7.58% and 8.63%) after oral administration. Regarding hypoglycemic effects on db/db mice, tD-G1A (50 µg/kg) lowered the glucose level more than bD-G1A (50 µg/kg) compared with the control (35.5% vs. 26.4%). CONCLUSION: GLP-1A was conjugated with oligomeric DOCAs, and the resulting chimeric compound showed the potential not only for glucagon-like peptide-1 receptor agonist activity but also for oral delivery. These findings suggest that oligomeric DOCAs can be used as effective carriers for oral delivery of GLP-1A, offering a promising solution for enhancing its oral bioavailability and improving diabetes treatment.

Enhancement of the anticancer effect of atorvastatin-loaded nanoemulsions by improving oral absorption via multivalent intestinal transporter-targeting lipids.

Atorvastatin (ATV) has attracted considerable attention as a potential therapeutic agent for cancer because it inhibits cancer cell proliferation by suppressing the mevalonate pathway. However, because of its low oral absorption, high doses of ATV are required for chemotherapeutic applications. In this study, we constructed ATV-loaded nanoemulsions (ATV-NEs) containing multivalent intestinal transporter-targeting lipids to improve the oral bioavailability of ATV. ATV-NEs were prepared via oil-in-water emulsification for transporter-targeted delivery, and contained the following anchors: an ionic complex of deoxycholic acid (DOCA) with the cationic lipid 1,2-dioleyl-3-trimethylammonium propane (DOTAP) (DOCA-DOTAP), a biotin-conjugated lipid (Biotinyl PE), and d-alpha-tocopherol polyethylene glycol succinate (TPGS) to allow bile acid- and multivitamin transporter-mediated permeation of ATV without P-glycoprotein (P-gp)-mediated efflux. The optimized formulation (ATV-NE#6) had 1,091% higher oral bioavailability than free ATV. Finally, treatment of 4T1 cell-bearing mice with oral ATV-NE#6 (equivalent to 40 mg/kg ATV) significantly suppressed tumor growth; the maximum tumor growth reduction was 2.44-fold that of the control group. The results thus suggest that ATV-NEs allow for effective oral chemotherapy by enhancing the oral bioavailability of ATV.

Sustained potentiation of bystander killing via PTEN-loss driven macropinocytosis targeted peptide-drug conjugate therapy in metastatic triple-negative breast cancer.

While conventional approaches for PTEN-loss cancers mainly focus on turning off growth promoting process through modulation of PI3K/AKT pathways, no effective therapeutic treatments that target PTEN-loss cancer cells have yielded results. Moreover, conventional targeted therapies, which are potent against only a subset of cancer cells with limited specificity, bring on temporary response. Here, we report the development of albumin-binding caspase-3 cleavable peptide-drug conjugate (PDC), which utilizes the enhanced albumin metabolism pathway in PTEN-loss cancer cells to enhance the intracellular delivery of chemotherapeutic payload that could exert a bystander killing effect. Albumin metabolism-mediated apoptosis triggered expression of caspase-3 allows the continuous activation of the PDC, accumulation of payloads, sustained upregulation of tumoral caspase-3, and intensified in-situ apoptosis. Importantly, PDC strategy exerts potent therapeutic efficacy against PTEN-loss metastatic triple-negative breast cancer, the highly aggressive and heterogenous nature of which remains a challenge conventional targeted therapies need to overcome. This study thus presents a conceptually novel approach to treat PTEN-loss cancer and creates new translational perspectives of exploiting PTEN-loss for providing an avenue to advance current targeted therapy.

Enhanced oral absorption of teriparatide with therapeutic potential for management of osteoporosis.

In this study, a system for oral delivery of recombinant human parathyroid hormone [rhPTH(1-34); teriparatide (TRP)] was developed to enhance oral absorption and to demonstrate an equivalent therapeutic effect to that of subcutaneous (SC) TRP injection. The solid oral formulation of TRP was prepared by electrostatic complexation with l-lysine-linked deoxycholic acid (LDA) and deoxycholic acid (DA) at a molar ratio of 1:5:7 in the aqueous dispersion of non-ionic n-dodecyl-ß-d-maltoside (DM) at a 1:15 weight ratio, followed by freeze-drying the dispersal, yielding TRP(1:5:7)-15. As expected, TRP(1:5:7)-15 showed a 414% increase in permeability across the Caco-2/HT29-MTX-E12 cell monolayer, resulting in a 13.0-fold greater oral bioavailability compared with free TRP. In addition, the intestinal transport mechanisms in the presence of specific inhibitors of clathrin-mediated endocytosis, macropinocytosis, and bile acid transporters revealed 44.4%, 28.7%, and 51.2% decreases in transport, respectively, confirming that these routes play crucial roles in the permeation of TRP in TRP(1:5:7)-15. Notably, this formulation showed similar activation of the release of cyclic adenosine monophosphate (cAMP) compared with TRP, suggesting equivalent efficacy in the parathyroid hormone receptor-adenylate cyclase system of osteosarcoma cells. Furthermore, oral TRP(1:5:7)-15 (equivalent to 0.4 mg/kg TRP) demonstrated increases in bone mineral density (36.9%) and trabecular thickness (31.3%) compared with untreated glucocorticoid-induced osteoporotic mice. Moreover, the elevated levels of biomarkers of bone formation, including osteocalcin, were also comparable with those after SC injection of TRP (0.02 mg/kg). These findings suggest that TRP(1:5:7)-15 can be used as an effective oral therapy for the management of osteoporosis.

Metronomic dose-finding approach in oral chemotherapy by experimentally-driven integrative mathematical modeling.

In conventional chemotherapy, maximum tolerated dose approach is considered as a first-line medication for cancer treatment in clinics. In contrast to the conventional chemotherapy which has heavy tumor burdens arising from high dose treatment, metronomic chemotherapy (MCT) engages relatively low dose without drug-free breaks, and is recognized as a promising strategy for a long-term management of the disease. Although doxorubicin (DOX), an anthracycline anti-cancer drug, showed a potential of maintenance effect in vitro, further study on in vivo-relevant concentration to achieve tumor suppression with no toxicity is required to apply the MCT in clinicals. Therefore, the objective of this study was to identify an optimal MCT regimen of DOX by determining concentration-response relationships of tumor suppression (pharmacodynamic; PD) and cardiac toxicity (toxicodynamic; TD). Utilizing an oral DOX formulation complexed with deoxycholic acid (DOX/DOCA complex) which has enhanced bioavailability, physiologically-based pharmacokinetic (PBPK) model was linked to TD and PD models to generate drug profiles from the combined PK, TD, and PD parameters. The integrated model was validated for various scenarios of administration route, formulation, dose, and frequency. The established mathematical model facilitated calculations of adequate in vivo-relevant dosages and intervals, suggesting the optimum oral metronomic regimen of DOX. It is expected to serve as a useful guideline for the design and evaluation of oral DOX formulations in future preclinical/clinical studies.

Feedback amplification of senolysis using caspase-3-cleavable peptide-doxorubicin conjugate and 2DG.

Therapy-induced senescence (TIS), a common outcome of current cancer therapy, is a known cause of late recurrence and metastasis and thus its eradication is crucial for therapy success. In this study, we introduced a conceptually novel strategy combining radiation-induced apoptosis-targeted chemotherapy (RIATC) with an effective glycolysis inhibitor, 2-deoxy-d-glucose (2DG) to target TIS. RIATC releases cytotoxic payload by amplification, continually increasing TIS, and this can be targeted by 2DG that stimulates an intrinsic apoptotic pathway in senescent cells, the senolysis; the senolytic 2DG also sensitizes cancer cells to chemo/radiation treatment. Anti-tumor efficacy of RIATC was investigated in numerous tumor models, and various cancer types were screened for TIS. Furthermore, in vitro evaluations of molecular markers of senescence, such as senescence-associated ß-galactosidase (SA-ß-Gal) assay, were performed to confirm that TIS was induced by RIATC therapy in MCF-7 cells. The combination therapy with 2DG proved to be effective in MCF-7 tumor-bearing mice that demonstrated feedback amplification of senolysis and successful inhibition of tumor growth. Our findings suggest that RIATC, when given together with 2DG, can overcome therapy-induced senescence and this combination is a promising strategy that enhances the therapeutic benefit of anti-cancer cytotoxic therapy.

Caspase-3 mediated switch therapy of self-triggered and long-acting prodrugs for metastatic TNBC.

Triple-negative breast cancer (TNBC) is characterized by its highly heterogeneous microenvironment and propensity for aggressive behavior, both of which represent, along with poor prognosis and high incidence of relapse, the main challenges of curing the disease. Although recent progress in targeted chemotherapy combinations has shown promising outcomes, conventional targeted chemotherapeutic approaches have relied on exploiting the expression of certain molecules or proteins overexpressed on cancer cells as drug targets, which have demonstrated limited clinical benefit against metastatic cancers. Here, we describe a tumoral caspase-3 mediated peptide-doxorubicin conjugates (PDC) switch therapy that adopts two different caspase-3 cleavable PDCs, RGDEVD-DOX (TPD1) and EMC-KGDEVD-DOX (MPD1), for targeting metastatic triple-negative breast cancer (mTNBC). First, using TPD1, an integrin αVß3 based targeted strategy was utilized to target tumor cells or tumor vasculature associated with the highly malignant progression of mTNBC. TPD1 triggered the tumor cell-specific initial apoptosis and the induction of caspase-3 expression in the target tumor site. Then MPD1 was administered sequentially, which is an albumin-binding prodrug, and activated by induced caspase-3 in order to maintain the tumoral caspase-3 level and release the cytotoxic payload. The PDC switch therapy markedly accumulated doxorubicin in the tumor site and augmented tumor-specific in situ amplification of apoptosis. Importantly, the PDC switch therapy exerted a bystander killing effect on the neighboring cancer cells thus demonstrating potent therapeutic efficacy against both local and metastatic cancers. Given the limited therapeutic outcomes with conventional targeted therapies, our strategy of regulating the expression of caspase-3 level as a drug target could provide as a more durable and effective alternative in the treatment of highly heterogeneous mTNBC.

Albumin metabolism targeted peptide-drug conjugate strategy for targeting pan-KRAS mutant cancer.

Despite recent breakthroughs in the development of direct KRAS inhibitors and modulators, no drugs targeting pan-KRAS mutant cancers are clinically available. Here, we report a novel strategy to treat pan-KRAS cancers using a caspase-3 cleavable peptide-drug conjugate that exploits enhanced albumin metabolism in KRAS altered cancers to deliver a cytotoxic agent that can induce a widespread bystander killing effect in tumor cells. Increased albumin metabolism in KRAS mutant cancer cells induced apoptosis via the intracellular uptake of albumin-bound MPD1. This allowed caspase-3 upregulation activated MPD1 to release the payload and exert the non-selective killing of neighboring cancer cells. MPD1 exhibited potent and durable antitumor efficacy in mouse xenograft models with different KRAS genotypes. An augmentation of anti-cancer efficacy was achieved by the bystander killing effect derived from the caspase-3 mediated activation of MPD1. In summary, albumin metabolism-induced apoptosis, together with the bystander killing effect of MPD1 boosted by caspase-3 mediated activation, intensified the efficacy of MPD1 in KRAS mutant cancers. These findings suggest that this novel peptide-drug conjugate could be a promising breakthrough for the treatment in the targeting of pan-KRAS mutant cancers.

Targeting angiogenic growth factors using therapeutic glycosaminoglycans on doppel-expressing endothelial cells for blocking angiogenic signaling in cancer.

Growth factors (GF) regulate normal development to cancer progression. GFs interact with extracellular matrix (ECM) biomolecules, such as heparin sulfate (HS) glycosaminoglycan (GAG), to enhance their stability and angiogenic signaling. Biomaterials that modulate GF activity by mimicking interactions observed in the native ECM could be designed as an effective treatment strategy. However, these materials failed to attenuate angiogenic signaling site-specifically without sparing normal tissues. In this work, we investigated the effect of a GAG-based biomaterial, which binds to the tumor endothelial cells (TEC), on the interaction among vascular endothelial growth factor (VEGF), its receptors-VEGFR2 and HS-and angiogenesis. Heparin-bile acid based conjugates, as ECM-mimicking component, were synthesized to selectively target the TEC marker doppel and doppel/VEGFR2 axis. The most effective compound LHbisD4 (low molecular weight heparin conjugated with 4 molecules of dimeric dexocholic acid) reduced tumor volume concentrated over doppel-expressing EC, and decreased tumor-interstitial VEGF without affecting its plasma concentration. Doppel-destined LHbisD4 captured VEGF, formed an intermediate complex with doppel, VEGFR2, and VEGF but did not induce active VEGFR2 dimerization, and competitively inhibited HS for VEGF binding. We thus show that GAG-based materials can be designed to imitate and leverage to control tumor microenvironment via bio-inspired interactions.

A novel oral metronomic chemotherapy provokes tumor specific immunity resulting in colon cancer eradication in combination with anti-PD-1 therapy.

In this study, we investigated the immune-modulating effects of a novel metronomic chemotherapy (MCT) featuring combined oral oxaliplatin (OXA) and pemetrexed (PMX) for colon cancer. OXA and PMX were ionically complexed with lysine derivative of deoxycholic acid (DCK), and incorporated into nanoemulsions or colloidal dispersions, yielding OXA/DCK-NE and PMX/DCK-OP, respectively, to improve their oral bioavailabilities. MCT was not associated with significant lymphotoxicity whereas the maximum tolerated dose (MTD) afforded systemic immunosuppression. MCT was associated with more immunogenic cell death and tumor cell MHC-class I expression than was MTD. MCT improved the tumor antigen presentation of dendritic cells and increased the number of functional T cells in the tumor. MCT also helped to enhance antigen-specific memory responses both locally and systemically. By combining MCT with anti-programmed cell death protein-1 (αPD-1) therapy, the tumor volume was suppressed by 97.85 ± 84.88% compared to the control, resulting in a 95% complete response rate. Upon re-challenge, all tumor-free mice rejected secondary tumors, indicating the induction of a tumor specific memory response. Thus, MCT using an OXA and PMX combination, together with αPD-1, successfully treated colon cancer by activating both innate and adaptive immune cells and elicited tumor-specific long-term immune memory while avoiding toxicity caused by MTD treatment.

Anticancer Effect of Heparin-Taurocholate Conjugate on Orthotopically Induced Exocrine and Endocrine Pancreatic Cancer.

Pancreatic cancers are classified based on where they occur, and are grouped into those derived from exocrine and those derived from neuroendocrine tumors, thereby experiencing different anticancer effects under medication. Therefore, it is necessary to develop anticancer drugs that can inhibit both types. To this end, we developed a heparin-taurocholate conjugate, i.e., LHT, to suppress tumor growth via its antiangiogenic activity. Here, we conducted a study to determine the anticancer efficacy of LHT on pancreatic ductal adenocarcinoma (PDAC) and pancreatic neuroendocrine tumor (PNET), in an orthotopic animal model. LHT reduced not only proliferation of cancer cells, but also attenuated the production of VEGF through ERK dephosphorylation. LHT effectively reduced the migration, invasion and tube formation of endothelial cells via dephosphorylation of VEGFR, ERK1/2, and FAK protein. Especially, these effects of LHT were much stronger on PNET (RINm cells) than PDAC (PANC1 and MIA PaCa-2 cells). Eventually, LHT reduced ~50% of the tumor weights and tumor volumes of all three cancer cells in the orthotopic model, via antiproliferation of cancer cells and antiangiogenesis of endothelial cells. Interestingly, LHT had a more dominant effect in the PNET-induced tumor model than in PDAC in vivo. Collectively, these findings demonstrated that LHT could be a potential antipancreatic cancer medication, regardless of pancreatic cancer types.

Metronomic delivery of orally available pemetrexed-incorporated colloidal dispersions for boosting tumor-specific immunity.

In this study, we developed oral pemetrexed (PMX) for metronomic dosing to enhance antitumor immunity. PMX was electrostatically complexed with positively charged lysine-linked deoxycholic acid (DL) as an intestinal permeation enhancer, forming PMX/DL, to enhance its intestinal permeability. PMX/DL was also incorporated into a colloidal dispersion (CD) comprised of the block copolymer of poly(ethylene oxide) and poly(propylene oxide), and caprylocaproyl macrogol-8 glycerides (PMX/DL-CD). CD-containing PMX/DL complex in a 1:1 molar ratio [PMX/DL(1:1)-CD] showed 4.66- and 7.19-fold greater permeability than free PMX through the Caco-2 cell monolayer and rat intestine, respectively. This resulted in a 282% improvement in oral bioavailability in rats. In addition, low-dose metronomic PMX led to more immunogenic cell death in CT26.CL25 cells compared to high PMX concentrations at the maximum tolerated dose. In CT26.CL25 tumor-bearing mice, oral metronomic PMX/DL-CD elicited greater antitumor immunity not only by enhancing the number of tumor-infiltrating lymphocytes but also by suppressing T cell functions. Oral PMX/DL-CD substantially increased programmed cell death protein ligand-1 (PD-L1) expression on tumor cells compared to the control and PMX-IV groups. This increased antitumor efficacy in combination with anti-programmed cell death protein-1 (aPD-1) antibody in terms of tumor rejection and immunological memory compared to the combination of PMX-IV and aPD-1. These results suggest that oral metronomic scheduling of PMX/DL-CD in combination with immunotherapy has synergistic antitumor effects.

Caspase-cleavable peptide-doxorubicin conjugate in combination with CD47-antagonizing nanocage therapeutics for immune-mediated elimination of colorectal cancer.

Here we report a novel combination of a caspase-cleavable peptide-doxorubicin conjugate (MPD-1) with CD47-antagonizing nanocage therapeutics for the treatment of microsatellite-stable (MSS) colorectal cancer (CRC). MPD-1 (i) upregulated markers of immunogenic cell death (ICD) in tumor, and increased co-stimulatory markers on dendritic cells (DCs), (ii) enhanced CD8+ T cell infiltration and antigen presenting cell (APC) activation, and (iii) showed negligible off-target immune-related toxicity compared to free dox. Then, the CD47 antagonist FS nanocage, a SIRPα-expressing ferritin nanocage, was co-administered with MPD-1 that resulted in 95.2% (p < 0.001) tumor growth inhibition in an established CRC model. T cell-mediated elimination of tumors was also confirmed by the tumor-specific activation of T cells detected by IFNγ and tumor-free mice were observed (95%) that bared a memory response when re-challenged. The strategically developed MPD-1 is an ideal adjuvant to immunotherapy and the combination with FS nanocage triggers potent immunity against MSS CRC. In summary, we present an approach to initiate and stimulate immune-mediated eradication of cancer cells using synergistic immunogenic agents targeting the MSS CRC.

Anticoagulation therapy promotes the tumor immune-microenvironment and potentiates the efficacy of immunotherapy by alleviating hypoxia.

PURPOSE: Here, this study verifies that cancer-associated thrombosis (CAT) accelerates hypoxia, which is detrimental to the tumor immune microenvironment by limiting tumor perfusion. Therefore, we designed an oral anticoagulant therapy to improve the immunosuppressive tumor microenvironment and potentiate the efficacy of immunotherapy by alleviating tumor hypoxia. EXPERIMENTAL DESIGN: A novel oral anticoagulant (STP3725) was developed to consistently prevent CAT formation. Tumor perfusion and hypoxia were analyzed with or without treating STP3725 in wild-type and P selectin knockout mice. Immunosuppressive cytokines and cells were analyzed to evaluate the alteration of the tumor microenvironment. Effector lymphocyte infiltration in tumor tissue was assessed by congenic CD45.1 mouse lymphocyte transfer model with or without anticoagulant therapy. Finally, various tumor models including K-Ras mutant spontaneous cancer model were employed to validate the role of the anticoagulation therapy in enhancing the efficacy of immunotherapy. RESULTS: CAT was demonstrated to be one of the perfusion barriers, which fosters immunosuppressive microenvironment by accelerating tumor hypoxia. Consistent treatment of oral anticoagulation therapy was proved to promote tumor immunity by alleviating hypoxia. Furthermore, this resulted in decrease of both hypoxia-related immunosuppressive cytokines and myeloid-derived suppressor cells while improving the spatial distribution of effector lymphocytes and their activity. The anticancer efficacy of αPD-1 antibody was potentiated by co-treatment with STP3725, also confirmed in various tumor models including the K-Ras mutant mouse model, which is highly thrombotic. CONCLUSIONS: Collectively, these findings establish a rationale for a new and translational combination strategy of oral anticoagulation therapy with immunotherapy, especially for treating highly thrombotic cancers. The combination therapy of anticoagulants with immunotherapies can lead to substantial improvements of current approaches in the clinic.

A supramolecular host-guest interaction-mediated injectable hydrogel system with enhanced stability and sustained protein release.

Injectable hydrogels have been studied as drug delivery systems because of their minimal invasiveness and sustained drug release properties. Pluronic F127, consisting of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymers, exhibits thermo-responsive properties and hence is injectable due to its rapid sol-gel transition. Unmodified Pluronic F127-based hydrogels, however, have limited long-term stability and controllable release of drugs entrapped within them. In this study, host-guest interactions between adamantane-conjugated Pluronic F127 (F127-Ad) and polymerized ß-cyclodextrin (CDP) were employed to develop a hydrogel-based protein delivery system. Single or multiple adamantane units were successfully introduced at the termini of Pluronic F127 with a 100% conversion yield, and the synthesized F127-Ad polymer produced a physically crosslinked micelle-packing structure when mixed with CDP. As the number of adamantanes at the terminal ends of Pluronic F127 increased, the critical gelation concentration of F127-Ad/CDP hydrogel decreased from 15 to 6% (w/v). The F127/CDP hydrogel was able to maintain its structure even with lower polymer content, and its injectability improved with a reduction of the hydrogel viscosity. The long-term stability of F127/CDP hydrogels was evaluated in vitro and in vivo, and it was demonstrated that the subcutaneously injected hydrogel did not disintegrate for up to 30 d. Throughout the drug release test using gelatin and insulin as model drugs, it was demonstrated that their release rates could be regulated via complexation between the protein drugs and the ß-cyclodextrin molecules inside the hydrogel. In conclusion, the F127-Ad/CDP hydrogel is expected to be a versatile protein delivery system with controllable durability and drug release characteristics. STATEMENT OF SIGNIFICANCE: Pluronic F127 is one of the widely studied polymeric materials for thermo-sensitive injectable hydrogels due to its high biocompatibility and rapid sol-gel transition. Since the Pluronic F127-based hydrogel has some limitations in its long-term stability and mechanical property, it is inevitable to modify its structure for the application to drug delivery. In this study, mono- or multi- adamantane-conjugated Pluronic F127s were synthesized and mixed with ß-cyclodextrin polymers to form hydrogels with host-guest interaction-mediated micelle-packing structures. The host-guest interaction introduced into the hydrogel system endowed it a sustained protein drug release behavior as well as high durability in vitro and in vivo. By increasing the number of adamantane molecules at the end of the Pluronic F127, both the stability and injectability of the hydrogel could be also modulated.

Exosomes and Cancer Stem Cells in Cancer Immunity: Current Reports and Future Directions.

Cancer stem cells (CSCs), which have the capacity to self-renew and differentiate into various types of cells, are notorious for their roles in tumor initiation, metastasis, and therapy resistance. Thus, underlying mechanisms for their survival provide key insights into developing effective therapeutic strategies. A more recent focus has been on exosomes that play a role in transmitting information between CSCs and non-CSCs, resulting in activating CSCs for cancer progression and modulating their surrounding microenvironment. The field of CSC-derived exosomes (CSCEXs) for different types of cancer is still under exploration. A deeper understanding and further investigation into CSCEXs' roles in tumorigenicity and the identification of novel exosomal components are necessary for engineering exosomes for the treatment of cancer. Here, we review the features of CSCEXs, including surface markers, cargo, and biological or physiological functions. Further, reports on the immunomodulatory effects of CSCEXs are summarized, and exosome engineering for CSC-targeting is also discussed.

Dual mechanistic TRAIL nanocarrier based on PEGylated heparin taurocholate and protamine which exerts both pro-apoptotic and anti-angiogenic effects.

The selective cytotoxicity of tumor necrosis factor-related apoptosis inducing ligand (TRAIL) to cancer cells but not to normal cells makes it an attractive candidate for cancer therapeutics. However, the disadvantages of TRAIL such as physicochemical instability and short half-life limit its further clinical applications. In this study, TRAIL was encapsulated into a novel anti-angiogenic nanocomplex for both improved drug distribution at the tumor site and enhanced anti-tumor efficacy. A nanocomplex was prepared firstly by entrapping TRAIL into PEG-low molecular weight heparin-taurocholate conjugate (LHT7), which is previously known as a potent angiogenesis inhibitor. Then, protamine was added to make a stable form of nanocomplex (PEG-LHT7/TRAIL/Protamine) by exerting electrostatic interactions. We found that entrapping TRAIL into the nanocomplex significantly improved both pharmacokinetic properties and tumor accumulation rate without affecting the tumor selective cytotoxicity of TRAIL. Furthermore, the anti-tumor efficacy of nanocomplex was highly augmented (73.77±4.86%) compared to treating with only TRAIL (18.49 ± 19.75%), PEG-LHT7/Protamine (47.84 ± 14.20%) and co-injection of TRAIL and PEG-LHT7/Protamine (56.26 ± 9.98%). Histological analysis revealed that treatment with the nanocomplex showed both anti-angiogenic efficacy and homogenously induced cancer cell apoptosis, which suggests that accumulated TRAIL and LHT7 in tumor tissue exerted their anti-tumor effects synergistically. Based on this study, we suggest that PEG-LHT7/Protamine complex is an effective nanocarrier of TRAIL for enhancing drug distribution as well as improving anti-tumor efficacy by exploiting the synergistic mechanism of anti-angiogenesis.

Synthesis of PEG-dendron for surface modification of pancreatic islets and suppression of the immune response.

Islet cell transplantation has been an effective method for the treatment of type 1 diabetes. The transplanted islets release insulin in response to changes in blood glucose levels. The clinical application of islet transplantation, however, has been hindered because of some critical problems including immune responses to grafted islets and side effects caused by overdosed immunosuppressive drugs. Herein, surface modification technology using poly(ethylene glycol) (PEG)-dendron was proposed to safeguard islets from the host immune system. PEG-dendron was synthesized by a divergent polymerization method and utilized to cover the islet antigen surface. Successful conjugation of PEG-dendron on the islet surface was achieved without affecting islet morphology, viability, and functionality at a concentration of 1.00%. Surface modification using PEG-dendron effectively prevented protein absorption and immune activation. Foremost, it improved the survival rate of islet grafts in vivo when combined with a low dose of immunosuppressive drugs. In conclusion, PEG-dendron is a potential candidate for the surface modification of pancreatic islets to mitigate immune responses after transplantation.