Epigenetic-based combination therapy and liposomal codelivery overcomes osimertinib-resistant NSCLC via repolarizing tumor-associated macrophages.

Osimertinib (Osi) is widely used as a first-line treatment for non-small cell lung cancer (NSCLC) with EGFR mutations. However, the majority of patients treated with Osi eventually relapse within a year. The mechanisms of Osi resistance remain largely unexplored, and efficient strategies to reverse the resistance are urgently needed. Here, we developed a lactoferrin-modified liposomal codelivery system for the combination therapy of Osi and panobinostat (Pan), an epigenetic regulator of histone acetylation. We demonstrated that the codelivery liposomes could efficiently repolarize tumor-associated macrophages (TAM) from the M2 to M1 phenotype and reverse the epithelial-mesenchymal transition (EMT)-associated drug resistance in the tumor cells, as well as suppress glycolysis, lactic acid production, and angiogenesis. Our results suggested that the combination therapy of Osi and Pan mediated by liposomal codelivery is a promising strategy for overcoming Osi resistance in NSCLC.

Construction of IMMS Containing Multi-site Liposomes for Dynamic Monitoring of Blood CTC in Patients with Osimertinib-resistant Non-small-cell Lung Cancer and its Mechanism.

OBJECTIVE: This article aims to establish a liquid biopsy system for gene detection of circulating tumor cells (CTC) in lung cancer, systematically analyze the significance of osimertinib resistance, and formulate an individualized diagnosis and treatment plan. METHODS: Liposome-contained magnetic microspheres coated with Fe3O4 nanoparticles were synthesized by microemulsion, and the surface was modified with EGFR antibody to form EGFR/EpCAM multi-site liposome-contained immunomagnetic microspheres (IMMSs). The CTCs were isolated and identified from peripheral blood samples and the cell lines of lung cancer patients collected by the multi-site liposome-contained IMMSs. To investigate the effects of the order of use of IMMSs sequence at different sites on the sorting and trapping efficiency of non-small-cell lung cancer (NSCLC) cells . The preliminary verification of drug-resistant gene function and dynamic monitoring of CTCs in 20 patients with EGFR-positive NSCLC were screened and statistically analyzed before and after osimertinib treatment. Sensitivity analysis and drug resistance evaluation of oxitidine were detected in vitro. RESULTS: Results showed the prepared multi-site liposome-contained IMMSs had high stability and specificity. The number of CTCs in blood samples of the patients with NSCLC was detected, revealing high sorting efficiency, and positive sorting rate reaching more than 90%. We investigated the effect of osimertinib on the HER-2 expression on the EGFR-mutated NSCLC cells and found that osimertinib increased the expression of HER-2 on the cell surface of NSCLC cell lines., And further explored the therapeutic potential of osimertinib combined with T-DM1 at different dosing times. CONCLUSION: Our results demonstrate that the prepared multi-site liposome-contained IMMSs can efficiently isolate CTCs from the peripheral blood in lung cancer. Combined with the experimental data about osimertinib can be effectively identified, the resistant genes of NSCLC including EGFR, which will provide a new scientific basis for guiding clinical medication and formulating individualized treatment plans.

Biocompatible hydrogels in spinal cord injury repair.

Spinal cord injury results in a permanent neurological deficit due to tissue damage. Such a lesion is a barrier for "communication" between the brain and peripheral tissues, effectors as well as receptors. One of the primary goals of tissue engineering is to bridge the spinal cord injury and re-establish the damaged connections. Hydrogels are biocompatible implants used in spinal cord injury repair. They can create a permissive environment and bridge the lesion cavities by providing a scaffold for the regeneration of neurons and their axons, glia and other tissue elements. The advantage of using artificial materials is the possibility to modify their physical and chemical properties in order to develop the best implant suitable for spinal cord injury repair. As a result, several types of hydrogels have been tested in experimental studies so far. We review our work that has been done during the last 5 years with various types of hydrogels and their applications in experimental spinal cord injury repair.

Chemical Interaction and Interface Analysis of Self-Etch Adhesives Containing 10-MDP and Methacrylamide With the Dentin in Noncarious Cervical Lesions.

OBJECTIVES: To characterize the chemical interactions and analyze the interface of adhesive systems containing 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) and N-methacryloyl glycine (methacrylamide) functional monomers with the dentin in noncarious cervical lesions (NCCLs) compared with artificial defects (ADs). METHODS AND MATERIALS: Twenty human teeth with natural NCCLs on the buccal surface were used. Class V cavities, similar to NCCLs, were created on the lingual surface to serve as controls. Teeth were randomly allocated to two groups according to the functional monomer in the adhesive (N=10): G1, 10-MDP; and G2, methacrylamide. NCCLs and ADs were characterized by their mineral composition (MC) and degree of demineralization (DD) using micro-Raman spectroscopy, adhesive/dentin chemical interactions (CIs) were assessed with infrared photoacoustic spectroscopy, and interface morphology was evaluated with scanning electron and light microscopy. MC, CI, and DD data were submitted to Shapiro-Wilk and Student t-tests ( p<0.05). RESULTS: Compared with ADs, dentin in NCCLs was hypermineralized ( p<0.05). In G1, CI, and DD in the first 2 µm, and adhesive projections in NCCLs and ADs interfaces were similar. Additionally, a thin layer of dentin collagen was observed in ADs, while it was hardly present in NCCLs. In G2, although CI could not be identified, changes in the mineral components were observed. The DD in the ADs and NCCLs were statistically similar, while SEM showed a lack of adhesion at NCCLs interface. DD and collagen exposure in the ADs and NCCLs were more pronounced than in G1. CONCLUSIONS: Results suggest that the G1 adhesive could be applied directly on the superficial sclerotic layer in NCCLs. In contrast, previous cavity preparation should be conducted to improve the micromechanical interaction of G2 with the dentin.

Anisotropic tough double network hydrogel from fish collagen and its spontaneous in vivo bonding to bone.

Soft supporting tissues in the human body, such as cartilages and ligaments, are tough materials and firmly fixed to bones. These soft tissues, once injured, cannot regenerate spontaneously in vivo. Developing tough and biocompatible hydrogels as artificial soft supporting tissues would substantially improve outcomes after soft tissue injury. Collagen is the main rigid component in soft connective tissues which is organized in various hierarchical arrays. We have successfully developed a novel class of collagen fibril-based tough hydrogels based on the double network (DN) concept using swim bladder collagen (SBC) extracted from Bester sturgeon fish. The DN hydrogels, SBC/PDMAAm, are composed of physically/chemically crosslinked anisotropic SBC fibril as the first network and neutral, biocompatible poly(N,N'-dimethylacrylamide) (PDMAAm) as the second network. The anisotropic structure of SBC fibril network, which is well retained in the DN hydrogels, is formed by free injection method, taking advantage of the excellent fibrillogenesis capacity of SBC. The denaturation temperature of collagen is improved in the DN hydrogels. These DN gels possess anisotropic swelling behavior, exhibit excellent mechanical properties comparable to natural cartilage. The 4 weeks implantation of the gels in the osteochondral defect of rabbit knee also shows excellent biomechanical performance in vivo. Furthermore, the hydroxyapatite (HAp) coated DN gels, HAp/SBC/PDMAAm gels, strongly bond to bone after 4 weeks. This new class of collagen-based hybrid DN gels, as soft and elastic ceramics, having good biomechanical performance and strong bonding ability with bone would expand the choice for designing next-generation orthopedic implants such as artificial cartilage, bone defect repair material in the load-bearing region of the body.

A Robust Method to Generate Mechanically Anisotropic Vascular Smooth Muscle Cell Sheets for Vascular Tissue Engineering.

In arterial tissue engineering, mimicking native structure and mechanical properties is essential because compliance mismatch can lead to graft failure and further disease. With bottom-up tissue engineering approaches, designing tissue components with proper microscale mechanical properties is crucial to achieve the necessary macroscale properties in the final implant. This study develops a thermoresponsive cell culture platform for growing aligned vascular smooth muscle cell (VSMC) sheets by photografting N-isopropylacrylamide (NIPAAm) onto micropatterned poly(dimethysiloxane) (PDMS). The grafting process is experimentally and computationally optimized to produce PNIPAAm-PDMS substrates optimal for VSMC attachment. To allow long-term VSMC sheet culture and increase the rate of VSMC sheet formation, PNIPAAm-PDMS surfaces were further modified with 3-aminopropyltriethoxysilane yielding a robust, thermoresponsive cell culture platform for culturing VSMC sheets. VSMC cell sheets cultured on patterned thermoresponsive substrates exhibit cellular and collagen alignment in the direction of the micropattern. Mechanical characterization of patterned, single-layer VSMC sheets reveals increased stiffness in the aligned direction compared to the perpendicular direction whereas nonpatterned cell sheets exhibit no directional dependence. Structural and mechanical anisotropy of aligned, single-layer VSMC sheets makes this platform an attractive microstructural building block for engineering a vascular graft to match the in vivo mechanical properties of native arterial tissue.

Tumor-targeted micelle-forming block copolymers for overcoming of multidrug resistance.

New amphiphilic diblock polymer nanotherapeutics serving simultaneously as a drug delivery system and an inhibitor of multidrug resistance were designed, synthesized, and evaluated for their physico-chemical and biological characteristics. The amphiphilic character of the diblock polymer, containing a hydrophilic block based on the N-(2-hydroxypropyl)methacrylamide copolymer and a hydrophobic poly(propylene oxide) block (PPO), caused self-assembly into polymer micelles with an increased hydrodynamic radius (Rh of approximately 15nm) in aqueous solutions. Doxorubicin (Dox), as a cytostatic drug, was bound to the diblock polymer through a pH-sensitive hydrazone bond, enabling prolonged circulation in blood, the delivery of Dox into a solid tumor and the subsequent stimuli-sensitive controlled release within the tumor mass and tumor cells at a decreased pH. The applicability of micellar nanotherapeutics as drug carriers was confirmed by an in vivo evaluation using EL4 lymphoma-bearing C57BL/6 mice. We observed significantly higher accumulation of micellar conjugates in a solid tumor because of the EPR effect compared with similar polymer-drug conjugates that do not form micellar structures or with the parent free drug. In addition, highly increased anti-tumor efficacy of the micellar polymer nanotherapeutics, even at a sub-optimal dose, was observed. The presence of PPO in the structure of the diblock polymer ensured, during in vitro tests on human and mouse drug-sensitive and resistant cancer cell lines, the inhibition of P-glycoprotein, one of the most frequently expressed ATP-dependent efflux pump that causes multidrug resistance. In addition, we observed highly increased rate of the uptake of the diblock polymer nanotherapeutics within the cells. We suppose that combination of unique properties based on MDR inhibition, stimuli sensitiveness (pH sensitive activation of drug), improved pharmacokinetics and increased uptake into the cells made the described polymer micelle a good candidate for investigation as potential drug delivery system.

Thermosensitive N-isopropylacrylamide-N-propylacrylamide-vinyl pyrrolidone terpolymers: synthesis, characterization and preliminary application as embolic agents.

In this article, thermosensitive N-isopropylacrylamide (NIPAAm)-N-propylacrylamide (NPAAm)-vinyl pyrrolidone (VP) terpolymers (PNINAVP) were prepared by varying feed ratios with free radical copolymerization method. The composition ratios and molecular weights of PNINAVP were examined by NMR and GPC. The thermo-responsive behaviors of copolymer solutions in the absence and with addition of Iohexol, a radiopaque agent, were investigated by differential scanning calorimetry (DSC) and rheometer. The sol-gel transition of the copolymer solutions occurred reversibly within 1 min in response to temperature. Incorporation of Iohexol increased the transition time and transition temperature of PNINAVP solutions; the rheological properties were also influenced. It was observed that at body temperature, PNINAVP and Iohexol could form an integrated bulky hydrogel presumably due to the hydrogen bonding between them, which was favorable for the clinical follow-up and reducing toxic side effects. In vitro embolic model experiment indicated that 5 wt% 16:16:1H PNINAVP solution containing Iohexol displayed a satisfactory embolization effect. This solution was injected into the rete mirabiles (RM) of six swines through a microcatheter. The angiographical results obtained immediately after the operation showed a complete occlusion of the RM, and no recanalization was observed at postoperative month 1. The histological examination demonstrated no acute inflammatory reaction inside the RM and surrounding tissue. This work could provide a beneficial guidance for designing a new temperature-sensitive polymer-based embolic agent.

An imaging-guided platform for synergistic photodynamic/photothermal/chemo-therapy with pH/temperature-responsive drug release.

To integrate biological imaging and multimodal therapies into one platform for enhanced anti-cancer efficacy, we have designed a novel core/shell structured nano-theranostic by conjugating photosensitive Au25(SR)18 - (SR refers to thiolate) clusters, pH/temperature-responsive polymer P(NIPAm-MAA), and anti-cancer drug (doxorubicin, DOX) onto the surface of mesoporous silica coated core-shell up-conversion nanoparticles (UCNPs). It is found that the photodynamic therapy (PDT) derived from the generated reactive oxygen species and the photothermal therapy (PTT) arising from the photothermal effect can be simultaneously triggered by a single 980 nm near infrared (NIR) light. Furthermore, the thermal effect can also stimulate the pH/temperature sensitive polymer in the cancer sites, thus realizing the targeted and controllable DOX release. The combined PDT, PTT and pH/temperature responsive chemo-therapy can markedly improve the therapeutic efficacy, which has been confirmed by both in intro and in vivo assays. Moreover, the doped rare earths endow the platform with dual-modal up-conversion luminescent (UCL) and computer tomography (CT) imaging properties, thus achieving the target of imaging-guided synergistic therapy under by a single NIR light.

S-Nitrosated human serum albumin dimer as novel nano-EPR enhancer applied to macromolecular anti-tumor drugs such as micelles and liposomes.

The enhanced permeability and retention (EPR) effect is a unique phenomenon of solid tumors, and it can serve as a basis for the development of macromolecular anticancer therapy. We have previously found that recombinant human serum albumin dimer, and especially its S-nitrosated form (SNO-HSA-Dimer), is an enhancer of the EPR effect. In this study, we investigated the influence of SNO-HSA-Dimer on the anti-tumor effect of two types of macromolecular anti-tumor drugs, namely N-(2-hydroxypropyl)methacrylamide polymer conjugated with zinc protoporphyrin, which forms micelles and can be used for fluorescence studies. The other was PEGylated liposomal doxorubicin (Doxil), a typical example of a stealth liposome approved for medical usage. In mice having C26 tumors with highly permeable vasculature, SNO-HSA-Dimer increases tumor accumulation of the drugs by a factor 3-4 and thereby their anti-tumor effects. Experiments with Evans blue revealed increased EPR effect in all parts of the tumor. Furthermore, SNO-HSA-Dimer improves the anti-metastatic effects of Doxil and reduces its minor uptake in non-tumorous organs such as liver and kidney. Tumor accumulation of Doxil in B16 tumors, which are characterized by a low permeable vasculature, increased even more (6-fold) in the presence of SNO-HSA-Dimer, and the improved accumulation lead to decreased tumor volume and increased survival of the animals. The administration of SNO-HSA-Dimer itself is safe, because it has no effect on blood pressure, heart rate or on several biochemical parameters. The present findings indicate that SNO-HSA-Dimer is promising for enhancing the EPR effect and consequently the specific, therapeutic effects of macromolecular anticancer drugs.

CT gel dosimetry technique: comparison of a planned and measured 3D stereotactic dose volume.

This study presents a 3D dose mapping of complex dose distributions using an x-ray computed tomography (CT) polymer gel dosimetry technique. Two polyacrylamide gels (PAGs) of identical composition were irradiated with the same four arc stereotactic treatment to maximum doses of 15 Gy (PAG1) and 8 Gy (PAG2). The PAGs were CT imaged using a previously defined protocol that involves image averaging and background subtraction to improve image quality. For comparison with the planned isodose distribution, the PAG images were converted to relative dose maps using a CT number-dose calibration curve or simple division. The PAG images were then co-registered with the planning CT images in the BrainLab treatment planning software which automatically provides reconstructed sagittal and coronal images for 3D evaluation of measured and planned dose. The hypo-intense high dose region in both sets of gel images agreed with the planned 80% isodose contour and was shifted by up to 1.5 and 3.0 mm in the axial and reconstructed planes, respectively. This demonstrates the ability of the CT gel technique to accurately localize the high dose region produced by the stereotactic treatment. The resulting agreement of the measured relative dose volume for PAG1 was within 3.0 mm for the 50% and 80% isodose surfaces. However, the dose contrast was too low in PAG2 to allow for accurate definition of measured relative dose surfaces. Thus, a PAG should be irradiated to higher doses if quantitative relative dose information is required. Unfortunately, this implies use of an additional PAG and its CT number dose response since doses greater than 8-10 Gy fall outside the linear regions of the response.

Poly(2-acrylamido-2-methylpropanesulfonic acid) gel induces articular cartilage regeneration in vivo: comparisons of the induction ability between single- and double-network gels.

The purpose of this study was to determine the in vivo cartilage induction effect of the poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) single-network (SN) gel and poly(N,N'-dimethyl acrylamide) (PDMAAm) SN gel in comparison with that of the PAMPS/PDMAAm double-network (DN) gel. An osteochondral defect created in rabbit trochlea was treated with PAMPS/PDMAAm DN, PAMPS SN, or PDMAAm SN gel implantation or left untreated. The gel was implanted into the defect so that a 2-mm depth remained. The defects were examined by histologic and immunohistochemical evaluations, surface assessment using confocal laser scanning microscopy, and real-time polymerase chain reaction analysis at 4 weeks. Samples were quantitatively evaluated with a scoring system reported by Wayne et al. The PAMPS/PDMAAm DN gel-implanted defect was filled with the hyaline-like cartilage tissue. The PAMPS SN gel-implanted defect was filled inhomogenously with hyaline/fibrocartilage tissue. The histology score of the defect treated with PAMPS/PDMAAm DN gel was significantly higher than those treated with PAMPS and PDMAAm SN gels, and the untreated defect (p = 0.0408, p < 0.0001, and p < 0.0001, respectively) and the scores of the defect treated with PAMPS SN gel were significantly higher than those treated with PDMAAm SN gel and the untreated defect (p = 0.0026 and p = 0.0026, respectively). These results suggested that the PAMPS SN gel has an ability that can induce hyaline cartilage regeneration in vivo, but that the PDMAAm SN gel does not. The current study indicates that the chondrogenic potential of a negatively charged PAMPS gel component plays an important role in the cartilage regeneration ability of the PAMPS/PDMAAm DN gel in vivo.

Induction of spontaneous hyaline cartilage regeneration using a double-network gel: efficacy of a novel therapeutic strategy for an articular cartilage defect.

BACKGROUND: A double-network (DN) gel, which was composed of poly-(2-acrylamido-2-methylpropanesulfonic acid) and poly-(N,N'-dimetyl acrylamide) (PAMPS/PDMAAm), has the potential to induce chondrogenesis both in vitro and in vivo. PURPOSE: To establish the efficacy of a therapeutic strategy for an articular cartilage defect using a DN gel. STUDY DESIGN: Controlled laboratory study. METHODS: A 4.3-mm-diameter osteochondral defect was created in rabbit trochlea. A DN gel plug was implanted into the defect of the right knee so that a defect 2 mm in depth remained after surgery. An untreated defect of the left knee provided control data. The osteochondral defects created were examined by histological and immunohistochemical evaluations, surface assessment using confocal laser scanning microscopy, and real-time polymerase chain reaction (PCR) analysis at 4 and 12 weeks. Samples were quantitatively evaluated with 2 scoring systems reported by Wayne et al and O'Driscoll et al. RESULTS: The DN gel-implanted defect was filled with a sufficient volume of the hyaline cartilage tissue rich in proteoglycan and type 2 collagen. Quantitative evaluation using the grading scales revealed a significantly higher score in the DN gel-implanted defects compared with the untreated control at each period (P < .0001). The mean relative values of type 2 collagen mRNAs in the regenerated tissue were obviously higher in the DN gel-implanted defect than in the untreated control at each period. The mean surface roughness of the untreated control was significantly higher than the normal cartilage at 12 weeks (P = .0106), while there was no statistical difference between the DN gel-implanted and normal knees. CONCLUSION: This study using the mature rabbit femoral trochlea osteochondral defect model demonstrated that DN gel implantation is an effective treatment to induce cartilage regeneration in vivo without any cultured cells or mammalian-derived scaffolds. CLINICAL RELEVANCE: This study has prompted us to develop a potential innovative strategy to repair cartilage lesions in the field of joint surgery.

Comparison of the efficacy of the embolic agents acrylamido polyvinyl alcohol microspheres and tris-acryl gelatin microspheres for uterine artery embolization for leiomyomas: a prospective randomized controlled trial.

OBJECTIVE: To evaluate the efficacy of acrylamido polyvinyl alcohol microspheres (a-PVAM) as an embolic agent for uterine artery embolization (UAE) compared with Tris-acryl gelatin microspheres (TAGM). DESIGN, SETTING, PARTICIPANTS: Prospective randomized double-blind noninferiority trial. Conducted at two sites both with regional UAE practices. Forty-six women with symptomatic leiomyomas. INTERVENTION: UAE procedure was performed with either of the two embolic agents. Either 700-900-µm a-PVAM or 500-700-µm TAGM was used. MAIN OUTCOME MEASURES: Changes in leiomyoma perfusion, overall uterine volume, and dominant leiomyomas volume measured by contrast-enhanced magnetic resonance imaging at 1 week, 3 months, and 6 months after UAE by a reader blinded to the embolic agent used. Changes in Uterine Fibroid Symptoms and Quality of Life questionnaire scores were measured at 3, 6, and 12 months after UAE. RESULTS: Forty-six patients were randomized and treated under the study protocol (a-PVAM n=22, TAGM n=24). There were no procedure-related complications. Two patients were excluded from analysis (one technical failure of the procedure, one withdrawal from study). Successful (>90%) leiomyoma devascularization was observed in 81% of subjects at 1 week after UAE, 97% at 3 months after UAE, and 95% at 6 months after UAE. No significant differences were observed in 14 of 15 outcome measurements, consistent with noninferiority. TAGM was slightly superior to a-PVAM on one comparison (overall quality of life at 3 months after UAE).

Do HPMA copolymer conjugates have a future as clinically useful nanomedicines? A critical overview of current status and future opportunities.

N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymer conjugates containing doxorubicin designed in the late 1970s/early 1980s as anticancer polymer therapeutics were the first synthetic polymer-based anticancer conjugates to enter clinical trial beginning in 1994. Early clinical results were promising, confirming activity in chemotherapy refractory patients and the safety of HPMA copolymers as a new polymer platform in this setting. Subsequent Phase I/II trials have investigated conjugates containing paclitaxel (PNU 166945), camptothecin (PNU 166148) (both failed in clinical trials underlining the importance of rational design), and most recently HPMA-copolymer platinates (AP5280 and then AP5346-ProLindac(TM)) entered Phase II clinical development. There are a growing array of second generation HPMA copolymer-based systems involving combination therapy, incorporating putative targeting ligands, having an ever more complex architecture, and both drug and protein conjugates are being proposed as novel treatments for diseases other than cancer. Despite their promise, and the success of polymeric drugs and polymer-protein conjugates, no polymer-drug conjugate (HPMA copolymer-based or otherwise) has yet entered routine clinical use. It is timely to reflect on the progress made over the last 30 years, the relative merits of HPMA copolymers as a platform compared to other polymeric carriers, and comment on their future potential as polymer-based nanomedicines into the 21st century in comparison with the many alternative strategies now emerging for creation of nanopharmaceuticals.

Beyond oncology--application of HPMA copolymers in non-cancerous diseases.

Macromolecular drug conjugates have been developed to improve the efficacy and safety profile of various therapeutic agents for many years. Among them, N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-drug conjugates are the most extensively studied delivery platforms for the effective treatment of cancer. In recent years, the applications of HPMA copolymers for the treatment of a broader range of non-cancerous diseases have also been explored. This review highlights the recent developments in the rational design, synthesis, and evaluation of novel HPMA copolymer-drug conjugates for non-cancerous diseases, such as musculoskeletal diseases, infectious diseases and spinal cord injury. The translation potential of these applications is also briefly discussed.

HPMA copolymers for masking and retargeting of therapeutic viruses.

Hydrophilic polymers are widely used already for steric stabilisation of bioactive proteins, changing their pharmacokinetics and modifying their interactions with the biological environment. Polymers may also be conjugated to biological surfaces, such as viruses, bacteria and mammalian cells, also to endow steric protection and changed properties. Reactive polymers based on N-[2-hydroxypropyl]methacrylamide have shown particular promise for surface coating of viruses, particularly adenovirus, and here we describe the important observations and innovations arising from this combination of chemical and genetic engineering. Adenovirus is a versatile agent that already finds important experimental applications as a recombinant vaccine, and also for cancer therapy, although its activity in both settings is often limited by a potent antibody-neutralising response in humans that is generally not seen in experimental animals. Coating with HPMA copolymers provides protection against neutralisation by antibodies and complement, and covalent linkage of novel ligands to the surface of the polymer can endow new infectious tropisms, mediated through different receptors, that can expand the potential applications of this versatile technology for a range of settings.

Hydrogel protection: a novel approach to reduce bowel inflammation in experimental gastroschisis.

OBJECTIVE: In gastroschisis there is herniation of the fetal bowel into the amniotic cavity that results in severe intestinal dysfunction. In order to reduce bowel exposure to amniotic fluid we used a hydrogel of N-isopropylacrylamide copolymerized with acrylic acid (P(NIPAAm-co-AAc)) to coat the herniated bowel through the use of a fibrin adhesive (Beriplast). STUDY DESIGN: Gastroschisis was created in fetuses of 31 pregnant Sprague-Dawley rats by evisceration of the bowel through a right paramedian incision in the abdominal wall on day 18.5 of pregnancy. The fetuses were separated in four groups of 12 fetuses: control (C), gastroschisis (G), gastroschisis+fibrin adhesive (GA) and gastroschisis+fibrin adhesive+dry hydrogel (GAH). Animals were harvested at day 21.5 of pregnancy and the hydrogel was removed. Fetuses and bowels were weighed and morphometric analysis was performed. Isoelectric focusing of the amniotic fluid determined its electrical charge. We evaluated the hydrogel swelling ratio (Q) in the amniotic fluid. Histological analysis and scanning electronic microscopy (SEM) of the bowel and hydrogel were performed. Our primary outcome was bowel intactness after hydrogel removal and our secondary outcome was the effectiveness of the hydrogel in protecting the bowel against amniotic fluid and its components. Differences among the groups were tested by the ANOVA and Tukey-Kramer post-test method and the statistical significance accepted was for p values <0.05. RESULTS: The mass of swollen hydrogel was 34 times the mass of dry hydrogel. Isoelectric focusing of the amniotic fluid showed that most of its proteins are negatively charged as the hydrogel. SEM showed that removal of the hydrogel did not damage bowel serosa. Bowel weight, diameter and wall thickness were similar between groups C and GAH but bowel diameter and wall thickness was significantly reduced in C and GAH compared to G and GA (p<0.001). CONCLUSION: The P(NIPAAm-co-AAc) hydrogel does not harm the bowel and provides a safe effective protection with reduction of bowel damage in gastroschisis.

Immunogenicity and immunomodulatory properties of HPMA-based polymers.

HPMA copolymers are one of the most promising drug carriers as their biophysical and biochemical properties, including their immunocompatibility, are very favorable. So far, there is no evidence that HPMA copolymers can interact with the immune system in a way that would lead either to suppression of some of its crucial functions or to inappropriate activation with possible serious side-effects and thus we can conclude that HPMA copolymers are convincingly proved to be "immunologically" safe. Moreover, it was shown both in mice and humans that HPMA copolymer-bound doxorubicin (DOX-HPMA) conjugates possess besides powerful anti-tumor effect also various immunomodulatory properties and exert significantly decreased side-toxicities, minimized bone marrow toxicity and cardiotoxicity being the most important ones. The possibility to induce potent and long-lasting tumor-specific immunity during the treatment with these compounds which is capable to provide protection against minimal residual disease is one of the most important and therapeutically valuable features of these conjugates.

Improving the efficacy of combined modality anticancer therapy using HPMA copolymer-based nanomedicine formulations.

Copolymers based on N-(2-hydroxypropyl)methacrylamide (HPMA) are prototypic and well-characterized polymeric drug carriers that have been broadly implemented in the delivery of anticancer agents. HPMA copolymers circulate for prolonged periods of time, and by means of the Enhanced Permeability and Retention (EPR) effect, they localize to tumors both effectively and selectively. Because of their beneficial biodistribution, and because of the fact that they are able to improve the balance between the efficacy and the toxicity of chemotherapy, it is reasonable to assume that HPMA copolymers combine well with other treatment modalities. In the present review, efforts in this regard are summarized, and HPMA copolymers are shown to be able to beneficially interact with surgery, with radiotherapy, with hyperthermia, with photodynamic therapy, with chemotherapy and with each other. Together, the insights provided and the evidence obtained strongly suggest that HPMA copolymer-based nanomedicine formulations hold significant potential for improving the efficacy of combined modality anticancer therapy.