Core-Shell type lipid/rPAA-Chol polymer hybrid nanoparticles for in vivo siRNA delivery

Our previous study had reported that cholesterol-grafted poly(amidoamine) (rPAA-Chol polymer) was able to self-assemble into cationic nanoparticles and act as a potential carrier for siRNA transfection. In this study, the core–shell type lipid/rPAA-Chol hybrid nanoparticles (PEG-LP/siRNA NPs and T7-LP/siRNA NPs) were developed for improving in vivo siRNA delivery by modifying the surface of rPAA-Chol/siRNA nanoplex core with a lipid shell, followed by post-insertion of polyethylene glycol phospholipid (DSPE-PEG) and/or peptide (HAIYPRH, named as T7) modified DSPE-PEG-T7. The integrative hybrid nanostructures of LP/siRNA NPs were evidenced by dynamic light scattering (DLS), confocal laser scanning microscope (CLSM), cryo-transmission electron microscope (Cryo-TEM) and surface plasmon resonance (SPR) assay. It was demonstrated that the T7 peptide modified LP/siRNA NPs (T7-LP/siRNA NPs) exhibited uniform and spherical structures with particle size of 99.39 ± 0.65 nm and surface potential of 42.53 ± 1.03 mV, and showed high cellular uptake efficiency and rapid endosomal/lysosomal escape ability in MCF-7 cells. Importantly, in vitro gene silencing experiment demonstrated that both of pegylated and targeted LP/siEGFR NPs exhibited significantly stronger downregulation of EGFR protein expression level in MCF-7 cells, compared to that of the physical mixture of siRNA lipoplexes and rPAA-Chol/siRNA nanoplexes. In vivo tumor therapy on nude mice bearing MCF-7 tumors further confirmed that the targeted T7-LP/siEGFR NPs exhibited the greatest inhibition on tumor growth via transferrin receptor-mediated targeting delivery, without any activation of immune responses and significant body weight loss following systemic administration. These findings indicated that the core-shell type T7-LP/siRNA nanoparticles would be promising siRNA delivery systems for in vivo tumor-targeted therapy.     

Vascular toxicity of ultra-small TiO2 nanoparticles and single walled carbon nanotubes in vitro and in vivo

Ultra-small nanoparticles (USNPs) at 1–3 nm are a subset of nanoparticles (NPs) that exhibit intermediate physicochemical properties between molecular dispersions and larger NPs. Despite interest in their utilization in applications such as theranostics, limited data about their toxicity exist. Here the effect of TiO₂-USNPs on endothelial cells in vitro, and zebrafish embryos in vivo, was studied and compared to larger TiO₂-NPs (30 nm) and to single walled carbon nanotubes (SWCNTs). In vitro exposure showed that TiO₂-USNPs were neither cytotoxic, nor had oxidative ability, nevertheless were genotoxic. In vivo experiment in early developing zebrafish embryos in water at high concentrations of TiO₂-USNPs caused mortality possibly by acidifying the water and caused malformations in the form of pericardial edema when injected. Myo1C involved in glomerular development of zebrafish embryos was upregulated in embryos exposed to TiO₂-USNPs. They also exhibited anti-angiogenic effects both in vitro and in vivo plus decreased nitric oxide concentration. The larger TiO₂-NPs were genotoxic but not cytotoxic. SWCNTs were cytotoxic in vitro and had the highest oxidative ability. Neither of these NPs had significant effects in vivo. To our knowledge this is the first study evaluating the effects of TiO₂-USNPs on vascular toxicity in vitro and in vivo and this strategy could unravel USNPs potential applications.     

Oral delivery of shRNA and siRNA via multifunctional polymeric nanoparticles for synergistic cancer therapy

Galactose modified trimethyl chitosan-cysteine (GTC) conjugates with various galactose grafting densities were developed for oral delivery of Survivin shRNA-expression pDNA (iSur-pDNA) and vascular endothelial growth factor (VEGF) siRNA (siVEGF) in the synergistic and targeted treatment of hepatoma. iSur-pDNA and siVEGF loaded GTC nanoparticles (NPs) were prepared via electrostatic complexation and showed desirable stability in physiological fluids and improved intestinal permeation compared to naked genes. Galactose grafting density of GTC NPs significantly affected their in vitro and in vivo antitumor activities. GTC NPs with moderate galactose grafting density, termed GTC2 NPs, were superior in facilitating cellular uptake, promoting nuclear distribution, and silencing target genes, leading to notable inhibition of cell growth. In tumor-bearing mice, orally delivered GTC2 NPs could effectively accumulate in the tumor tissues and silence the expression of Survivin and VEGF, evoking increased apoptosis, inhibited angiogenesis, and thus the most efficient tumor regression. Moreover, compared with single gene delivery, co-delivery of iSur-pDNA and siVEGF showed synergistic effects on inhibiting in vitro cell proliferation and in vivo tumor growth. This study could serve as an effective approach for synergistic cancer therapy via oral gene delivery, and highlighted the importance of ligand grafting density in the rational design of targeted nanocarriers.     

Efficient in vitro and in vivo pulmonary delivery of nucleic acid by carbon dot-based nanocarriers

Cationic carbon dots were fabricated by pyrolysis of citric acid and bPEI25k under microwave radiation. Various nanoparticles were produced in a 20–30% yield through straightforward modifications of the reaction parameters (stoichiometry of the reactants and energy supply regime). Particular attention was paid to the purification of the reaction products to ensure satisfactory elimination of the residual starting polyamine. Intrinsic properties of the particles (size, surface charge, photoluminescence and quantum yield) were measured and their ability to form stable complexes with nucleic acid was determined. Their potential to deliver plasmid DNA or small interfering RNA to various cell lines was investigated and compared to that of bPEI25k. The pDNA in vitro transfection efficiency of these carbon dots was similar to that of the parent PEI, as was their cytotoxicity. The higher cytotoxicity of bPEI25k/siRNA complexes when compared to that of the CD/siRNA complexes however had marked consequences on the gene silencing efficiency of the two carriers. These results are not fully consistent with those in some earlier reports on similar nanoparticles, revealing that toxicity of the carbon dots strongly depends on their protocol of fabrication. Finally, these carriers were evaluated for in vivo gene delivery through the non-invasive pulmonary route in mice. High transgene expression was obtained in the lung that was similar to that obtained with the golden standard formulation GL67A, but was associated with significantly lower toxicity. Post-functionalization of these carbon dots with PEG or targeting moieties should significantly broaden their scope and practical implications in improving their in vivo transfection efficiency and biocompatibility.     

Uptake and transfection efficiency of PEGylated cationic liposome–DNA complexes with and without RGD-tagging

Steric stabilization of cationic liposome–DNA (CL–DNA) complexes is required for in vivo applications such as gene therapy. PEGylation (PEG: poly(ethylene glycol)) of CL–DNA complexes by addition of PEG2000-lipids yields sterically stabilized nanoparticles but strongly reduces their gene delivery efficacy. PEGylation-induced weakening of the electrostatic binding of CL–DNA nanoparticles to cells (leading to reduced uptake) has been considered as a possible cause, but experimental results have been ambiguous. Using quantitative live-cell imaging in vitro, we have investigated cell attachment and uptake of PEGylated CL–DNA nanoparticles with and without a custom synthesized RGD-peptide grafted to the distal ends of PEG2000-lipids. The RGD-tagged nanoparticles exhibit strongly increased cellular attachment as well as uptake compared to nanoparticles without grafted peptide. Transfection efficiency of RGD-tagged PEGylated CL–DNA NPs increases by about an order of magnitude between NPs with low and high membrane charge density (σ_M; the average charge per unit area of the membrane; controlled by the molar ratio of cationic to neutral lipid), even though imaging data show that uptake of RGD-tagged particles is only slightly enhanced by high σ_M. This suggests that endosomal escape and, as a result, transfection efficiency of RGD-tagged NPs is facilitated by high σ_M. We present a model describing the interactions between PEGylated CL–DNA nanoparticles and the anionic cell membrane which shows how the PEG grafting density and membrane charge density affect adhesion of nanoparticles to the cell surface.     

Acid-degradable core–shell nanoparticles for reversed tamoxifen-resistance in breast cancer by silencing manganese superoxide dismutase (MnSOD)

Drug resistance acquired by cancer cells is a significant challenge in the clinic and requires impairing the responsible pathological pathway. Administering chemotherapeutics along with silencing resistance-basis activity using RNA interference (RNAi) is expected to restore the activity of the chemotherapeutic and generate synergistic cancer eradication. This study attempted to reverse tamoxifen (TAM)-resistance in breast cancer by silencing a mitochondrial enzyme, manganese superoxide dismutase (MnSOD), which dismutates TAM-induced reactive oxygen species (ROS) (i.e., superoxide) to less harmful hydrogen peroxide and hampers therapeutic effects. Breast cancer cells were co-treated with TAM and MnSOD siRNA-delivering nanoparticles (NPs) made of a siRNA/poly(amidoamine) (PAMAM) dendriplex core and an acid-degradable polyketal (PK) shell. The (siRNA/PAMAM)-PK NPs were designed for the PK shell to shield siRNA from nucleases, minimize detrimental aggregation in serum, and facilitate cytosolic release of siRNA from endosomal compartments. This method of forming the PK shell around the siRNA/PAMAM core via surface-initiated photo-polymerization enables ease of tuning NPs' size for readily controlled siRNA release kinetics. The resulting NPs were notably homogenous in size, resistant to aggregation in serum, and invulnerable to heparan sulfate-mediated disassembly, compared to siRNA/PAMAM dendriplexes. Gel electrophoresis and confocal microscopy confirmed efficient siRNA release from the (siRNA/PAMAM)-PK NPs upon stimuli-responsive hydrolysis of the PK shell. Sensitization of TAM-resistant MCF7-BK-TR breast cancer cells with (MnSOD siRNA/PAMAM)-PK NPs restored TAM-induced cellular apoptosis in vitro and significantly suppressed tumor growth in vivo, as confirmed by biochemical assays and histological observations. This study implies that combined gene silencing and chemotherapy is a promising strategy to overcoming a significant challenge in cancer therapy.     

Nanovaccine loaded with poly I:C and STAT3 siRNA robustly elicits anti-tumor immune responses through modulating tumor-associated dendritic cells in vivo

Although cancer vaccine-based immunotherapy holds great potential for cancer treatment, tumor-induced dendritic cell (DC) dysfunction remains to be the major obstacle for developing effective vaccines. Compared with normal DCs, tumor-associated DCs (TADCs) are less matured with poor responsiveness to Toll-like receptor (TLR) stimulation, which has been related with STAT3 hyperactivity. In the present study, Poly I:C (PIC, a TLR3 agonist), STAT3 siRNA and OVA antigen were co-encapsulated by poly (ethylene glycol)-b-poly (l-lysine)-b-poly (l-leucine) (PEG-PLL-PLLeu) polypeptide micelles to generate PMP/OVA/siRNA nanovaccine, which was aimed to effectively overcome DC dysfunction in vivo by deleting STAT3 gene in situ. The results showed that PMP/OVA/siRNA simultaneously facilitated the cellular uptake of OVA antigen and siRNA about 3–200 folds, and decreased STAT3 expression in TADCs over 50% both in vitro and in vivo. PMP/OVA/siRNA also elevated CD86 and CD40 expression as well as IL-12 production by TADCs more effectively than PMP/OVA did, indicating its strong potency of inducing TADC maturation and activation. Moreover, the immunization of PMP/OVA/siRNA rather than PMP/OVA effectively abrogated immunosuppression in the tumor microenvironment by increasing mature DCs and decreasing immunosuppressive cells in tumor-draining lymph nodes, which thereby led to potent anti-tumor immune responses and dramatic tumor regression with prolonged survival. Hence, in vivo co-delivery of immunopotentiator (PIC) and immunosuppressive gene silencer (STAT3 siRNA) by nanovaccines are expected to be a promising strategy to improve the therapeutic efficacy of cancer vaccines by modulating TADCs and overcoming tumor immunosupression.     

Active leukocyte detachment and apoptosis/necrosis on PEG hydrogels and the implication in the host inflammatory response

Monocytes/Macrophages have long been recognized as key players in inflammation and wound healing and are often employed in vitro to gain an understanding of the inflammatory response to biomaterials. Previous work has demonstrated a drastic decrease in primary monocyte adherent density on biomaterial surfaces coupled with a change in monocyte behavior over time. However, the mechanism responsible for this decrease remains unclear. In this study, we explored active detachment and cellular death as possible regulating factors. Specifically, extracellular TNF-α and ROS production were analyzed as potential endogenous stimulators of cell death. MMPs, but not calpains, were found to play a key role in active monocyte detachment. Monocyte death was found to peak at 24 h and occur by both apoptosis and necrosis as opposed to polymorphonuclear leukocyte death which mainly occurred through apoptosis. Finally, TNF-α and ROS production were not found to have a causal relationship with monocyte death on TCPS or PEG surfaces. The occurrence of primary monocyte apoptosis/necrosis as well as active detachment from a material surface has implications not only in in vitro study, but also in the translation of the in vitro inflammatory response of these cells to in vivo applications.     

Synergistic inhibition of breast cancer by co-delivery of VEGF siRNA and paclitaxel via vapreotide-modified core–shell nanoparticles

A somatostatin analog, vapreotide (VAP), can be used as a ligand for targeting drug delivery based on its high affinity to somatostatin receptors (SSTRs), which is overexpressed in many tumor cells. RNA interference plays an important role on downregulation of vascular endothelial growth factor (VEGF), which is important for tumor growth, progression and metastasis. To improve tumor therapy efficacy, the vapreotide-modified core–shell type nanoparticles co-encapsulating VEGF targeted siRNA (siVEGF) and paclitaxel (PTX), termed as VAP-PLPC/siRNA NPs, were developed in this study. When targeted via somatostatin receptors to tumor cells, the VAP-PLPC/siRNA NPs could simultaneously delivery siVEGF and PTX into cells and achieve a synergistic inhibition of tumor growth. Interestingly, in vitro cell uptake and gene silencing experiments demonstrated that the targeted VAP-PLPC/siRNA NPs exhibited significant higher intracellular siRNA accumulation and VEGF downregulation in human breast cancer MCF-7 cells, compared to those of the non-targeted PEG-PLPC/siRNA NPs. More importantly, in vivo results further demonstrated that the targeted VAP-PLPC/siRNA NPs had significant stronger drug distribution in tumor tissues and tumor growth inhibition efficacy via receptor-mediated targeting delivery, accompany with an obvious inhibition of neovascularization induced by siVEGF silencing. These results suggested that the co-delivery of siRNA and paclitaxel via vapreotide-modified core–shell nanoparticles would be a promising approach for tumor targeted therapy.     

Transferrin-conjugated magnetic silica PLGA nanoparticles loaded with doxorubicin and paclitaxel for brain glioma treatment

The effective treatment of malignant brain glioma is hindered by the poor transport across the blood–brain barrier (BBB) and the low penetration across the blood-tumor barrier (BTB). In this study, transferrin-conjugated magnetic silica PLGA nanoparticles (MNP-MSN-PLGA-Tf NPs) were formulated to overcome these barriers. These NPs were loaded with doxorubicin (DOX) and paclitaxel (PTX), and their anti-proliferative effect was evaluated in vitro and in vivo. The in vitro cytotoxicity of drug-loaded NPs was evaluated in U-87 cells. The delivery and the subsequent cellular uptake of drug-loaded NPs could be enhanced by the presence of magnetic field and the usage of Tf as targeting ligand, respectively. In particular, cells treated with DOX-PTX-NPs-Tf with magnetic field showed the highest cytotoxicity as compared to those treated with DOX-PTX-NPs-Tf, DOX-PTX-NPs, DOX-PTX-NPs-Tf with free Tf. The in vivo therapeutic efficacy of drug-loaded NPs was evaluated in intracranial U-87 MG-luc2 xenograft of BALB/c nude mice. In particular, the DOX-PTX-NPs-Tf treatment exhibited the strongest anti-glioma activity as compared to the PTX-NPs-Tf, DOX-NPs-Tf or DOX-PTX-NPs treatment. Mice did not show acute toxicity after administrating with blank MNP-MSN-PLGA-Tf NPs. Overall, MNP-MSN-PLGA-Tf NPs are promising carriers for the delivery of dual drugs for effective treatment of brain glioma.     

Non-covalently functionalized single-walled carbon nanotube for topical siRNA delivery into melanoma

RNAi can specifically regulate gene expression, but efficient delivery of siRNA in vivo is difficult while it has been shown that modified carbon nanotubes (CNT) protect siRNA, facilitate entry into cells and enhance transdermal drugs delivery. Single-walled carbon nanotubes (SWCNT) were functionalized non-covalently with succinated polyethyleimine (PEI-SA). In this study, the water soluble CNT, PEI-SA/CNT (IS/C) were isolated and characterized, the gene silencing induced by IS/C/siRNA complexes was achieved in vitro in B16-F10 cells. In vivo delivery was topically applied to shaved mouse skin, as well as topically to a C57BL/6 mice melanoma model. We found significant uptake of Cy3-labeled siRNA specific to Braf (siBraf) and gene silencing in the tumor tissue. Treatment with IS/C/siBraf resulted in attenuation of tumor growth over a 25-day period. This new delivery method has provided a new possibility for future siRNA delivery and therapy, which providing insight for the potential application and development of CNT-based siRNA delivery.     

Multifunctional,self-assembling anionic peptide-lipid nanocomplexes for targeted siRNA delivery

Formulations of cationic liposomes and polymers readily self-assemble by electrostatic interactions with siRNA to form cationic nanoparticles which achieve efficient transfection and silencing in vitro. However, the utility of cationic formulations in vivo is limited due to rapid clearance from the circulation, due to their association with serum proteins, as well as systemic and cellular toxicity. These problems may be overcome with anionic formulations but they provide challenges of self-assembly and transfection efficiency. We have developed anionic, siRNA nanocomplexes utilizing anionic PEGylated liposomes and cationic targeting peptides that overcome these problems. Biophysical measurements indicated that at optimal ratios of components, anionic PEGylated nanocomplexes formed spherical particles and that, unlike cationic nanocomplexes, were resistant to aggregation in the presence of serum, and achieved significant gene silencing although their non-PEGylated anionic counterparts were less efficient. We have evaluated the utility of anionic nanoparticles for the treatment of neuronal diseases by administration to rat brains of siRNA to BACE1, a key enzyme involved in the formation of amyloid plaques. Silencing of BACE1 was achieved in vivo following a single injection of anionic nanoparticles by convection enhanced delivery and specificity of RNA interference verified by 5′ RACE-PCR and Western blot analysis of protein.     

Combined mTOR inhibitor rapamycin and doxorubicin-loaded cyclic octapeptide modified liposomes for targeting integrin α3 in triple-negative breast cancer

A novel therapeutic strategy combining mTOR inhibitor rapamycin (RAPA) and doxorubicin (DOX)-loaded cyclic octapeptide liposomes for targeting integrin α3 was expected to combat the triple-negative breast cancer (TNBC). RAPA was loaded into PEG–PCL polymer micelles (M-RAPA) to realize solubilization. Flow cytometry analysis and laser confocal microscopy were used to evaluate the in vitro cellular uptake. The in vivo tumor targeting and bio-distribution were investigated by living fluorescence imaging. As the results, LXY modification significantly enhanced the cellular uptake of liposomal DOX in integrin α3 overexpressed TNBC cells (MDA-MB-231) in vitro and accordingly improved the tumor accumulation of liposomes in vivo. When used alone or in combination with LXY-LS-DOX, M-RAPA could greatly inhibit the expression of HIF-1α protein, which is always highly expressed in malignant cancers and involved in tumor angiogenesis, proliferation, therapeutic resistance and poor prognosis. Meanwhile, the improved efficacy of combined targeted therapy with LXY-LS-DOX and M-RAPA was demonstrated by the in vitro cytotoxicity against model TNBC cells and in vivo anti-tumor activity against mouse bearing TNBC model. These results suggested that the targeted combinational therapy based on LXY-LS-DOX and M-RAPA systems may provide a rational strategy to improve therapeutic outcomes of TNBC.     

Systematic in vitro and in vivo study on porous silicon to improve the oral bioavailability of celecoxib

Mesoporous materials are promising candidates for improving dissolution rate of poorly water-soluble drugs in vitro and their bioavailability in vivo. In the present study, sixteen batches of celecoxib-loaded PSi particles with pore sizes ranging from 17 to 58 nm and celecoxib content from 5 to 36 w-% were prepared and a detailed physicochemical characterization of the drug was performed by several methods. Interaction between co-culture of Caco-2/HT29-MTX cells and unloaded PSi particles was tested in toxicity assays, and increased toxicity for particles with large pore size was observed. Dissolution rate of celecoxib was improved in vitro by lowering the drug loading degree which hindered the recrystallization of celecoxib on the external surface of the particles. The fastest permeation of loaded celecoxib through the co-culture monolayer as well as the highest bioavailability in rats was observed with the particles with small pore size and low loading degree. New insights were obtained on how various parameters of the mesoporous delivery system affect the state of the drug inside the pores and its release in vitro and in vivo.     

A phenotypic in vitro model for the main determinants of human whole heart function

This article details the construction and testing of a phenotypic assay system that models in vivo cardiac function in a parallel in vitro environment with human stem cell derived cardiomyocytes. The major determinants of human whole-heart function were experimentally modeled by integrating separate 2D cellular systems with BioMicroelectromechanical Systems (BioMEMS) constructs. The model features a serum-free defined medium to enable both acute and chronic evaluation of drugs and toxins. The integration of data from both systems produced biologically relevant predictions of cardiac function in response to varying concentrations of selected drugs. Sotalol, norepinephrine and verapamil were shown to affect the measured parameters according to their specific mechanism of action, in agreement with clinical data. This system is applicable for cardiac side effect assessment, general toxicology, efficacy studies, and evaluation of in vitro cellular disease models in body-on-a-chip systems.     

Effects of hydrophobic core components in amphiphilic PDMAEMA nanoparticles on siRNA delivery

Due to their biodegradable character, polyesters such as polycaprolactone (PCL), poly(d,l-lactide) (PDLLA), and polylactic-co-glycolic acid (PLGA) were widely used as the hydrophobic cores of amphiphilic cationic nanoparticles (NPs) for siRNA delivery. However, fewer researches focused on facilitating siRNA delivery by adjusting the polyester composition of these nanoparticles. Herein, we investigated the contribution of polyester segments in siRNA delivery in vitro by introducing different ratio of DLLA moieties in PCL segments of mPEG-block-PCL-graft-poly(dimethylamino ethyl methacrylate)(PEG-b-PCL-g-PDMAEMA). It was noticed that compared with the other ratios of DLLA moieties, a certain molar ratio (about 70%) of the NPs, named mPEG₄₅-P(CL₂₁-co-DLLA₄₈)-g-(PDMAEMA₂₉)₂ (PECLD-70), showed the highest gene knockdown efficiency but poorest cellular uptake ability in vitro. Further research revealed that NPs with various compositions of the polyester cores showed different physicochemical properties including particle size, zeta potential and stiffness, leading to different endocytosis mechanisms thus influencing the cellular uptake efficiency. Subsequently, we observed that the cells treated by PECLD-70 NPs/Cy5 siRNA complexes exhibited more diffuse Cy5 signal distribution than other NPs by confocal laser scanning microscope, which suggested that siRNA delivered by PECLD-70 NPs/Cy5 siRNA complexes possessed of stronger capabilities in escaping from endosome/lysosome, entering the RNA-induced silencing complex (RISC) and cutting the target mRNA efficiently. The different siRNA release profile was dominated by the degradation rate of polyester segments. Therefore, it could be concluded that the adjustment of hydrophobic core of cationic nanoparticles could significantly affect their transfection behavior and appropriate polyester composition should be concerned in designing of analogous siRNA vectors.     

Biomaterials with persistent growth factor gradients in vivo accelerate vascularized tissue formation

Gradients of soluble factors play an important role in many biological processes, including blood vessel assembly. Gradients can be studied in detail in vitro, but methods that enable the study of spatially distributed soluble factors and multi-cellular processes in vivo are limited. Here, we report on a method for the generation of persistent in vivo gradients of growth factors in a three-dimensional (3D) biomaterial system. Fibrin loaded porous poly (ethylene glycol) (PEG) scaffolds were generated using a particulate leaching method. Platelet derived growth factor BB (PDGF-BB) was encapsulated into poly (lactic-co-glycolic acid) (PLGA) microspheres which were placed distal to the tissue–material interface. PLGA provides sustained release of PDGF-BB and its diffusion through the porous structure results in gradient formation. Gradients within the scaffold were confirmed in vivo using near-infrared fluorescence imaging and gradients were present for more than 3 weeks. The diffusion of PDGF-BB was modeled and verified with in vivo imaging findings. The depth of tissue invasion and density of blood vessels formed in response to the biomaterial increased with magnitude of the gradient. This biomaterial system allows for generation of sustained growth factor gradients for the study of tissue response to gradients in vivo.     

Multilayer nanoparticles for sustained delivery of exenatide to treat type 2 diabetes mellitus

A method for the sustained delivery of exenatide was proposed using nanoparticles (NPs) with a core/shell structure. The interactions between lipid bilayers and Pluronics were utilized to form various NPs using a layer-by-layer approach. Transmittance electron microscopy and dynamic light scattering were used to examine the morphology of the NPs. The in vitro release pattern was observed as a function of changes in the structure of the NPs, and the structural integrity of exenatide released was examined by SDS–PAGE analysis. Pharmacokinetics and antidiabetic effects were also observed with the structural change of NPs using in vivo animal models. In vitro–in vivo correlation was discussed in relation to manipulation of the NP structures.     

Novel human-derived extracellular matrix induces in vitro and in vivo vascularization and inhibits fibrosis

The inability to vascularize engineered organs and revascularize areas of infarction has been a major roadblock to delivering successful regenerative medicine therapies to the clinic. These investigations detail an isolated human extracellular matrix derived from the placenta (hPM) that induces vasculogenesis in vitro and angiogenesis in vivo within bioengineered tissues, with significant immune reductive properties. Compositional analysis showed ECM components (fibrinogen, laminin), angiogenic cytokines (angiogenin, FGF), and immune-related cytokines (annexins, DEFA1) in near physiological ratios. Gene expression profiles of endothelial cells seeded onto the matrix displayed upregulation of angiogenic genes (TGFB1, VEGFA), remodeling genes (MMP9, LAMA5) and vascular development genes (HAND2, LECT1). Angiogenic networks displayed a time dependent stability in comparison to current in vitro approaches that degrade rapidly. In vivo, matrix-dosed bioscaffolds showed enhanced angiogenesis and significantly reduced fibrosis in comparison to current angiogenic biomaterials. Implementation of this human placenta derived extracellular matrix provides an alternative to Matrigel and, due to its human derivation, its development may have significant clinical applications leading to advances in therapeutic angiogenesis techniques and tissue engineering.