Macrophage-specific Delivery Research Articles

A multiscale modeling study of nanoparticle-based targeting therapy against atherosclerosis

Although researches on nanoparticle-based (NP-based) drug delivery system for atherosclerosis treatment have grown rapidly in recent years, there are limited studies in quantifying the effects of targeting drugs on plaque components and microenvironment. The purpose of the present study was to quantitatively assess the targeting therapeutic effects against atherosclerosis by establishing a multiscale mathematical model.The multiscale model involved subcellular, cellular and microenvironmental scales to simulate lipid catabolism, macrophage behaviors and dynamics of microenvironmental components, respectively. In vitro and in vivo experimental data were integrated into the mathematical model according to Bayesian statistics, in order to evaluate the therapeutic effects of a proposed NP-based platform for macrophage-specific delivery to simultaneously deliver SR-A siRNA (to reduce LDL uptake) and LXR-L (to stimulate cholesterol efflux). Dosage variation analysis was then performed to investigate the drug efficacy under varied dosage combinations of SR-A siRNA and LXR-L.The simulation results demonstrated that the dynamics of the microenvironmental components presented different developments in Untreated and Treated groups. We also found that the balance of lipid metabolism between uptake and efflux resulted in the improvement of lipid and inflammatory microenvironment, consequently in the plaque regression. In addition, the model predicted optimized dosage combinations according to the co-effect analysis of the two drugs on the lipid microenvironment.This study suggests that multiscale modeling can be a powerful quantitative tool for estimating the therapeutic effects of targeting drugs for plaque regression and designing the enhanced treatment strategies against atherosclerosis.

Inhibition of mevalonate pathway by macrophage-specific delivery of atorvastatin prevents their pro-inflammatory polarisation.

Adjustment of the cellular metabolism of pro-inflammatory macrophages is essential for their bactericidal function; however, it underlies the development of many human diseases if induced chronically. Therefore, intervention of macrophage metabolic polarisation has been recognised as a potent strategy for their treatment. Although many small-molecule inhibitors affecting macrophage metabolism have been identified, their in vivo administration requires a tool for macrophage-specific delivery to limit their potential side effects. Here, we establish Drosophila melanogaster as a simple experimental model for in vivo testing of macrophage-specific delivery tools. We found that yeast-derived glucan particles (GPs) are suitable for macrophage-specific delivery of small-molecule inhibitors. Systemic administration of GPs loaded with atorvastatin, the inhibitor of hydroxy-methyl-glutaryl-CoA reductase (Hmgcr), leads to intervention of mevalonate pathway specifically in macrophages, without affecting HMGCR activity in other tissues. Using this tool, we demonstrate that mevalonate pathway is essential for macrophage pro-inflammatory polarisation and individual's survival of infection.

Precision treatment of viral pneumonia through macrophage-targeted lipid nanoparticle delivery

Macrophages are integral components of the innate immune system, playing a dual role in host defense during infection and pathophysiological states. Macrophages contribute to immune responses and aid in combatting various infections, yet their production of abundant proinflammatory cytokines can lead to uncontrolled inflammation and worsened tissue damage. Therefore, reducing macrophage-derived proinflammatory cytokine release represents a promising approach for treating various acute and chronic inflammatory disorders. However, limited macrophage-specific delivery vehicles have hindered the development of macrophage-targeted therapies. In this study, we screened a pool of 112 lipid nanoparticles (LNPs) to identify an optimal LNP formulation for efficient siRNA delivery. Subsequently, by conjugating the macrophage-specific antibody F4/80 to the LNP surface, we constructed MacLNP, an enhanced LNP formulation designed for targeted macrophage delivery. In both in vitro and in vivo experiments, MacLNP demonstrated a significant enhancement in targeting macrophages. Specifically, delivery of siRNA targeting TAK1, a critical kinase upstream of multiple inflammatory pathways, effectively suppressed the phosphorylation/activation of NF-kB. LNP-mediated inhibition of NF-kB, a key upstream regulator in the classic inflammatory signaling pathway, in the murine macrophage cell line RAW264.7 significantly reduced the release of proinflammatory cytokines after stimulation with the viral RNA mimic Poly(I:C). Finally, intranasal administration of MacLNP-encapsulated TAK1 siRNA markedly ameliorated lung injury induced by influenza infection. In conclusion, our findings validate the potential of targeted macrophage interventions in attenuating inflammatory responses, reinforcing the potential of LNP-mediated macrophage targeting to treat pulmonary inflammatory disorders.

Hyaluronic acid nanoparticle-encapsulated microRNA-125b repolarizes tumor-associated macrophages in pancreatic cancer.

Aim: To investigate a novel strategy to target tumor-associated macrophages and reprogram them to anantitumor phenotype in pancreatic adenocarcinoma (PDAC). Methods: M2 peptideswere conjugated to HA-PEG/HA-PEI polymer to form self-assembled nanoparticles with miR-125b. The efficacy of HA-PEI/PEG-M2peptide nanoparticles in pancreatic tumors from LSL-KrasG12D/+, LSL-Trp53R172H/+, Pdx1-Cre genetically engineered micewas evaluated. Results:In vitro M2 macrophage-specific delivery of targeted nanoformulationswas demonstrated. Intraperitoneal administration of M2-targeted nanoparticles showed preferential accumulation in the pancreas of KPC-PDAC mice and an abovefourfold increase in the M1-to-M2 macrophage ratio compared with transfection with scrambled miR. Conclusion: M2-targeted HA-PEI/PEG nanoparticles with miR-125b can transfect tumor-associated macrophages in pancreatic tissues and may have implications for PDAC immunotherapy.

Nanoparticle-based “Two-pronged” approach to regress atherosclerosis by simultaneous modulation of cholesterol influx and efflux

Reduction of lipoprotein uptake by macrophages and stimulation of cholesterol efflux are two essential steps required for atherosclerotic plaque regression. We used the optimized mannose-functionalized dendrimeric nanoparticle (mDNP)-based platform for macrophage-specific delivery of therapeutics to simultaneously deliver SR-A siRNA (to reduce LDL uptake) and LXR ligand (LXR-L, to stimulate cholesterol efflux) – a novel “Two-pronged” approach to facilitate plaque regression. mDNP-mediated delivery of SR-A siRNA led to a significant reduction in SR-A expression with a corresponding decrease in uptake of oxLDL. Delivery of LXR-L increased expression of ABCA1/G1 and cholesterol efflux. Combined delivery of siRNA and LXR-L led to a significantly greater decrease in macrophage cholesterol content compared to either treatment alone. Administration of this in vitro optimized formulation of mDNP complexed with SR-A-siRNA and LXR-L (Two-pronged complex) to atherosclerotic LDLR−/− mice fed western diet (TD88137) led to significant regression of atherosclerotic plaques with a corresponding decrease in aortic cholesterol content.

Collaborative assembly-mediated siRNA delivery for relieving inflammation-induced insulin resistance

Obesity plays a primary causative role in insulin resistance and hyperglycemia that contributes to type 2 diabetes. Excess lipid storage in the liver renders activation of the resident macrophages and chronic secretion of inflammatory mediators, therefore causing or aggravating insulin resistance. Herein, we develop collaborative assemblies using a “one-pot” synthesis method for macrophage-specific delivery of small interfering RNAs (siRNAs) that target the inflammatory proteins. Ternary nanocomplex (NC) composed of the siRNA molecule, a synthetic thiol-bearing methacrylated hyaluronic acid (sm-HA) and protamine forms through an electrostatic-driven physical assembly, which is chemically crosslinked to acquire the collaboratively assembled nanocapsule (cNC) concurrently. The obtained cNC displays significantly higher stability than NC. Functional moieties as flexible assembly units can be easily equipped on cNC for long circulation, active targeting, or controlled siRNA release. cNC-F decorated with folic acid, a macrophage-targeting ligand promotes the siRNA accumulation in the activated macrophages in the liver of the obese mouse model. cNC-F loaded with siRNA targeting inflammatory indicators efficiently control the macrophage inflammatory response by reducing the expression of the inflammatory proteins (> 40% reduction) and ameliorating the insulin resistance symptoms of the obese mice.

Abstract A169: Macrophage targeted zoledronic acid conjugated biomineral nanoparticles for γδT-cell-based cancer immunotherapy

Abstract Nanoparticle platforms can be engineered to deliver immune-stimulatory molecules to specific immune cell populations, thereby evoke desired response. Here, we present a novel biomineral nanoparticle system for macrophage specific delivery of bisphosphonate molecules to evoke activation of γδ T-cells for cancer immunotherapy. Generally, γδ T-cells therapy is implemented either by ex vivo expansion followed by adoptive transfer or by in vivo activation using intravenous injection of bisphosphonates. One of the major limitations of intravenously injection of bisphosphonates such as zoledronic acid is its unfavorable biodistribution in the skeletal system due to covalent binding with calcium in the bone. In the present work, we have pre-conjugated zoledronic acid in a calcium-containing biomineral nanoparticle (Zol-BM) that has spontaneous specificity towards macrophages in the liver, spleen and lymph nodes. This enabled targeted expression of γδT-cell stimulating ligand, isopentyl pyrophosphate, in macrophages, leading to enhanced activation of γδT-cells. Optimized Zol-BM showed a drug conjugation efficiency of ~95% with particle size ~ 100 nm and zeta potential, -15mV. The compatibility of Zol-BM was tested in primary human peripheral blood mononuclear cells and macrophages cell lines. The biodistribution analysis of Zol-BM in healthy rat models showed accumulation in liver, spleen and lymph nodes which was confirmed by MRI and Prussian-blue analysis. Flow cytometry based γδT-cell proliferation analysis gave ~18% enhancement in γδ T-cell subset compared to untreated control. Thus, we show that by rational design of engineered nanoparticles, specific immuno-stimulatory molecules like zolendronate can be delivered to desired immune cells of interest (macrophages) for activating another sub-population of immune cells such as γδ T-cells, for cancer-immunotherapy applications. Citation Format: Anusha Ashokan, Minu Anoop, Siju Surendran, Aparna Balakrishnan, Ida M. Anna, Anjana Ramkumar, Girish Chundayil Madathil, Vijay Harish, Manzoor Koyakutty. Macrophage targeted zoledronic acid conjugated biomineral nanoparticles for γδT-cell-based cancer immunotherapy [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A169.

Repolarization of Tumor-Associated Macrophages in a Genetically Engineered Nonsmall Cell Lung Cancer Model by Intraperitoneal Administration of Hyaluronic Acid-Based Nanoparticles Encapsulating MicroRNA-125b.

Tumor-associated macrophages (TAMs) acquire a pro-tumor (M2) phenotype, which promotes tumor growth, angiogenesis, and metastasis. Certain microRNAs (miRs), such as miR-125b, can reprogram TAMs into an antitumor/pro-inflammatory (M1) phenotype. Using CD44 targeting hyaluronic acid-poly(ethylenimine) (HA-PEI)-based nanoparticles encapsulating miR-125b, we have herein shown macrophage-specific delivery and transfection upon intraperitoneal (i.p.) administration. We have exploited the inherent ability of peritoneal macrophages to migrate toward the inflammation/injury and demonstrated that following intraperitoneal administration of HA-PEI nanoparticles, there is an accumulation of HA-PEI nanoparticles in the macrophage-ablated lung tissues of both naïve and KRAS/p53 double mutant genetically engineered (KP-GEM) nonsmall cell lung cancer (NSCLC) mouse model. Additionally, upon transfection with miR-125b, we observed a >6-fold increase in the M1 to M2 macrophage ratio and 300-fold increase in the iNOS (M1 marker)/Arg-1 (M2 marker) ratio in TAMs as compared to the untreated control group. The results of these studies show that i.p. administered macrophage-specific HA-PEI nanoparticles can successfully transfect TAMs in lung tissues of both naïve mice and a KP-GEM NSCLC mouse model. Successful TAM repolarization toward the M1 phenotype has significant implication in anticancer immunotherapy.

Development of mannose functionalized dendrimeric nanoparticles for targeted delivery to macrophages: use of this platform to modulate atherosclerosis

Dysfunctional macrophages underlie the development of several diseases including atherosclerosis where accumulation of cholesteryl esters and persistent inflammation are 2 of the critical macrophage processes that regulate the progression as well as stability of atherosclerotic plaques. Ligand-dependent activation of liver-x-receptor (LXR) not only enhances mobilization of stored cholesteryl ester but also exerts anti-inflammatory effects mediated via trans-repression of proinflammatory transcription factor nuclear factor kappa B. However, increased hepatic lipogenesis by systemic administration of LXR ligands (LXR-L) has precluded their therapeutic use. The objective of the present study was to devise a strategy to selectively deliver LXR-L to atherosclerotic plaque-associated macrophages while limiting hepatic uptake. Mannose-functionalized dendrimeric nanoparticles (mDNP) were synthesized to facilitate active uptake via the mannose receptor expressed exclusively by macrophages using polyamidoamine dendrimer. Terminal amine groups were used to conjugate mannose and LXR-L T091317 via polyethylene glycol spacers. mDNP-LXR-L was effectively taken up by macrophages (and not by hepatocytes), increased expression of LXR target genes (ABCA1/ABCG1), and enhanced cholesterol efflux. When administered intravenously to LDLR-/- mice with established plaques, significant accumulation of fluorescently labeled mDNP-LXR-L was seen in atherosclerotic plaque-associated macrophages. Four weekly injections of mDNP-LXR-L led to significant reduction in atherosclerotic plaque progression, plaque necrosis, and plaque inflammation as assessed by expression of nuclear factor kappa B target gene matrix metalloproteinase 9; no increase in hepatic lipogenic genes or plasma lipids was observed. These studies validate the development of a macrophage-specific delivery platform for the delivery of anti-atherosclerotic agents directly to the plaque-associated macrophages to attenuate plaque burden.

PGE2-treated macrophages inhibit development of allergic lung inflammation in mice.

In healthy lungs, many macrophages are characterized by IL-10 production, and few are characterized by expression of IFN regulatory factor 5 (formerly M1) or YM1 and/or CD206 (formerly M2), whereas in asthma, this balance shifts toward few producing IL-10 and many expressing IFN regulatory factor 5 or YM1/CD206. In this study, we tested whether redressing the balance by reinstating IL-10 production could prevent house dust mite-induced allergic lung inflammation. PGE2 was found to be the best inducer of IL-10 in macrophages in vitro. Mice were then sensitized and challenged to house dust mites during a 2 wk protocol while treated with PGE2 in different ways. Lung inflammation was assessed 3 d after the last house dust mite challenge. House dust mite-exposed mice treated with free PGE2 had fewer infiltrating eosinophils in lungs and lower YM1 serum levels than vehicle-treated mice. Macrophage-specific delivery of PGE2 did not affect lung inflammation. Adoptive transfer of PGE2-treated macrophages led to fewer infiltrating eosinophils, macrophages, (activated) CD4(+), and regulatory T lymphocytes in lungs. Our study shows that the redirection of macrophage polarization by using PGE2 inhibits development of allergic lung inflammation. This beneficial effect of macrophage repolarization is a novel avenue to explore for therapeutic purposes.

Rifampicin loaded mannosylated cationic nanostructured lipid carriers for alveolar macrophage-specific delivery.

In this study, cationic mannosylated nanostructured lipid carriers (Man-NLCs) were developed for the targeted delivery of rifampicin to alveolar macrophages. Rifampicin loaded Man-NLCs (RFP-Man-NLCs) and rifampicin loaded unmodified nanostructured lipid carriers (REP-NLCs) were prepared using thin film homogenization method and characterized by particle size, polydispersity index, zeta potential, transmission electron microscopy, encapsulation efficiency, pharmacokinetics, biodistribution, cell specific targeting, cytotoxicity and inflammatory response. RFP-Man-NLCs and REP-NLCs obtained displayed a size distribution around 160 nm (PDI <0.30) with positive charges of approximately 30 mV. The encapsulation efficiency of RFP was above 90%. In the biodistribution study, both RFP-Man-NLCs and RFP-NLCs, compared with the commercially available rifampicin solution, displayed superior lung-targeting ability. Compared to REP-NLCs, RFP-Man-NLCs exhibited significantly higher uptake efficiency in NR8383 cells and alveolar macrophages, which achieved cell-specific targeting. In addition, RFP-Man-NLCs were demonstrated to be a safe formulation with minimum toxicity and no inflammatory response. RFP-Man-NLCs provided an alternative strategy for selectively delivering rifampicin to alveolar macrophages.

Abstract 18998: Macrophage-Specific Mineralocorticoid Receptor Antagonists for Cardiovascular Disease

Background: Mineralocorticoid receptor antagonists (MRA) have consistently led to improved clinical outcomes in patients with cardiovascular disease. Despite these benefits, off-target effects have limited the use of MRAs. Studies have begun to define the molecular mechanisms underlying cell-specific MR signaling, with several groups demonstrating a pathologic role for macrophage-MR activation in animal models of heart failure. Objective: We sought to engineer and evaluate a macrophage-specific MRA (Mf-MRA) composed of three elements: a nanoparticle delivery platform, the MRA eplerenone, and a fluorogenic biomarker for therapeutic monitoring. Methods and Results: The individual elements of the Mf-MRA were assembled using click chemistry. Bone marrow-derived macrophages (BMDM) and control cell models were used to evaluate the cell-specificity and therapeutic efficacy of the Mf-MRA. Using flow cytometry, we found that the Mf-MRA internalizes and is activated specifically in macrophages and not other cells. To confirm the functionality of the Mf-MRA, we evaluated oxidative stress induction and inflammatory gene expression in BMDM in response to aldosterone (Aldo). Equivalent concentrations (1 μM) of spironolactone and the Mf-MRA blocked Aldo induced superoxide production (Figure 1). Additionally, the Mf-MRA blocked Aldo induction of TNFα gene transcription (p&lt;0.005). Finally, preliminary studies in a murine heart failure model confirmed the macrophage-specific delivery and activation of the Mf-MRA. Conclusions: We have developed a novel, macrophage-specific MRA using a synthetic nanoparticle, a fluorogenic biomarker, and an established MRA. This cell-specific MRA combines targeted-delivery with therapeutic monitoring. We believe that this innovative platform will have unique diagnostic and therapeutic applications for a broad spectrum of cardiovascular diseases.

Development of nanocapsules bearing doxorubicin for macrophage targeting through the phosphatidylserine ligand: a system for intervention in visceral leishmaniasis

The purpose of this study was to explore the applicability, targeting potential and drug delivery to specialized phagocytes via phosphatidylserine (PS)-specific ligand-anchored nanocapsules (NCs) bearing doxorubicin. The layer-by-layer method was utilized to prepare NCs having a nanoemulsion core loaded with doxorubicin (NCs-DOX), which was further grafted with PS. PS-coated NCs (PS-NCs-DOX) were compared with NCs-DOX for in vitro targeting ability by studying uptake by macrophages, intracellular localization, in vivo pharmacokinetics and organ distribution studies. The in vivo antileishmanial activity of free doxorubicin, NCs-DOX and PS-NCs-DOX was tested against visceral leishmaniasis in Leishmania donovani-infected hamsters. Flow cytometric data revealed 1.75-fold enhanced uptake of PS-NCs-DOX in J774A.1 macrophage cell lines compared with NCs-DOX. In vivo organ distribution studies in Wistar rats demonstrated a significantly higher extent of accumulation of PS-NCs-DOX compared with NCs-DOX in macrophage-rich organs, particularly in liver and spleen. Highly significant antileishmanial activity (P < 0.05 compared with NCs) was observed with PS-NCs-DOX, causing 85.23% ± 4.49% inhibition of splenic parasitic burden. NCs-DOX and free doxorubicin caused only 72.88% ± 3.87% and 42.85% ± 2.11% parasite inhibition, respectively, in Leishmania-infected hamsters (P < 0.01 for PS-NCs-DOX versus free doxorubicin and NCs-DOX versus free doxorubicin). We conclude that the PS targeting moiety can provide a new insight for efficient drug delivery to specialized macrophages and thus may be developed for effective use in macrophage-specific delivery systems, especially for leishmaniasis.

Microspheres based on mannosylated lysine-co-sodium alginate for macrophage-specific delivery of isoniazid

Abstract The present investigation reports coupling of ɛ- and α-amino groups of lysine (LS) with mannose (m-LS) and sodium alginate (SA), respectively, to reduce its toxicity. Prepared conjugate, m-LS-co-SA, was characterized through infra-red spectroscopy and differential scanning calorimetry. Cell viability studies were undertaken to assess the safety profile of the prepared conjugate. Microspheres, based on the conjugate, were prepared using spray drying technique and studied for targeting of isoniazid to alveolar macrophages (AMs). Pharmacokinetic studies of the optimized formulation batch were performed in Charles Foster rats. Infra-red spectral data of the synthesized conjugate were in agreement to the presumptive sequence of the conjugation process. Dispersibility, thermal stability and safety of the conjugate were conducive to its biomedical application. Microspheres, formulated from the conjugate, were of uniform size and offered satisfactory drug loading efficiency and in vitro release characteristics. X-ray diffraction studies established that drug was entrapped within the microspheres rather than being adsorbed on to the surface. Pharmacokinetic studies revealed that the conjugate could be a potential vehicle towards both active targeting of isoniazid to AMs and controlling its release rate.

In vitro evaluation of surface functionalized gelatin nanoparticles for macrophage targeting in the therapy of visceral leishmaniasis

The present study evaluates the potential of surface functionalized gelatin nanoparticles (f-GNPs) for efficient macrophage-specific delivery of amphotericin B (AmB) in the treatment of visceral leishmaniasis (VL). Further, the effect of spacer for macrophage targeting was also evaluated. Gelatin was functionalized either through conjugation to mannose via direct coupling (mGelatin) or via PEG spacer (m-Gelatin), and the synthesis was confirmed by FTIR. AmB-loaded f-GNPs, that is, mGNPs and m-GNPs prepared from mGelatin and m-Gelatin conjugates, respectively, were characterized. In vitro concanavalin A (Con-A) agglutination assay confirmed the availability of mannose on the surface of these f-GNPs. Kinetics of cellular uptake of AmB-loaded f-GNPs by J774A.1 macrophage cells assessed through flow cytometry demonstrated a steady increase and maximum cell-associated fluorescence was observed at 4h for m-GNPs and 6 h for m-GNPs. Measurement of cytotoxicity using Annexin-V–FITC/PI apoptosis assay delineated marginal changes (7–9%) in treated macrophages following 48 h incubation, establishing the safety of f-GNPs. m-GNPs showed a 5.4-fold reduction in IC50 in comparison with plain AmB suggesting significant enhancement of antileishmanial activity. Our results indicate that f-GNPs could be a promising carrier for specific delivery of AmB to macrophages for effective treatment of VL. Furthermore, spacer contributed significantly in reducing the cytotoxicity as well as increasing the uptake and activity of f-GNPs.

Development of a Synthetic Promoter for Macrophage Gene Therapy

Macrophages have the potential to deliver therapeutic genes to many target tissues. Macrophage-specific synthetic promoters (SPs) generated by random ligation of myeloid/macrophage cis elements had activity up to 100-fold that of a native macrophage promoter in macrophage cell lines, but were minimally active in nonmyeloid cells. Mouse bone marrow cells (BMCs) transduced ex vivo with lentivectors expressing green fluorescent protein (GFP) driven either by an SP (SP-GFP) or a cytomegalovirus (CMV) promoter (CMV-GFP) were used for syngeneic transplantation of lethally irradiated mice. Blood leukocytes showed stable GFP expression for up to 15 months after transplantation. SP-GFP expression was selective for CD11b+ macrophages, whereas CMV-GFP expression was observed in erythrocytes, as well as in both CD11b+ and CD11b- leukocytes. Furthermore, SP-GFP expression was much stronger than CMV-GFP expression in CD11b+ macrophages. apoE-/- BMCs transduced with the lentiviral vector encoding human apoE were used to transplant apoE-/- mice. Macrophage expression of apoE from 10 to 26 weeks of age significantly reduced atherosclerotic lesions in recipient apoE-/- mice. Thus, the novel SPs, especially when combined with lentivectors, are useful for macrophage-specific delivery of therapeutic genes.

Development of a Synthetic Promoter for Macrophage Gene Therapy

Macrophages have the potential to deliver therapeutic genes to many target tissues. Macrophage-specific synthetic promoters (SPs) generated by random ligation of myeloid/macrophage cis elements had activity up to 100-fold that of a native macrophage promoter in macrophage cell lines, but were minimally active in nonmyeloid cells. Mouse bone marrow cells (BMCs) transduced ex vivo with lentivectors expressing green fluorescent protein (GFP) driven either by an SP (SP-GFP) or a cytomegalovirus (CMV) promoter (CMV-GFP) were used for syngeneic transplantation of lethally irradiated mice. Blood leukocytes showed stable GFP expression for up to 15 months after transplantation. SP-GFP expression was selective for CD11b+ macrophages, whereas CMV-GFP expression was observed in erythrocytes, as well as in both CD11b+ and CD11b- leukocytes. Furthermore, SP-GFP expression was much stronger than CMV-GFP expression in CD11b+ macrophages. apoE-/- BMCs transduced with the lentiviral vector encoding human apoE were used to transplant apoE-/- mice. Macrophage expression of apoE from 10 to 26 weeks of age significantly reduced atherosclerotic lesions in recipient apoE-/- mice. Thus, the novel SPs, especially when combined with lentivectors, are useful for macrophage-specific delivery of therapeutic genes.

Macrophage specific drug delivery in experimental leishmaniasis.

Macrophage-specific delivery systems are the subject of much interest nowadays, because of the fact that macrophages act as host cells for many parasites and bacteria, which give rise to outbreak of so many deadly diseases(eg. leishmaniasis, tuberculosis etc.) in humans. To combat these deadly diseases initially macrophage specific liposomal delivery system were thought of and tested in vivo against experimental leishmaniasis in hamsters using a series of indigenous or synthetic antileishmanial compounds and the results were critically discussed. In vitro testing was also done against macrophages infected with Leishmania donovani, the causative agent for visceral leishmaniasis. The common problem of liposome therapy being their larger size, stability and storage, non-ionic surfactant vesicles, niosomes were prepared, for their different drug distribution and release characteristics compared to liposomes. When tested in vivo, the retention capacity of niosomes was found to be higher than that of liposomes due to the absence of lipid molecules and their smaller size. Thus the therapeutic efficacy of certain antileishmanial compounds was found to be better than that in the liposomal form. The niosomes, being cheaper, less toxic, biodegradable and non-immunogenic, were considered for sometime as suitable alternatives to liposomes as drug carriers. Besides the advent of other classical drugs carriers(e.g. neoglycoproteins), the biggest challenge came from polymeric delivery vehicles, specially the polymeric nanoparticles which were made of cost effective biodegradable polymers and different natural polymers. Because of very small size and highly stable nature, use of nanoparticles as effective drug carriers has been explored in experimental leishmaniasis using a series of antileishmanial compounds, both of indigenous and synthetic origin. The feasibility of application in vivo, when tested for biological as well as for other physicochemical parameters, the polymeric nanoparticles have turned out to be the best and thus may be projected for effective use in the clinics.

Targeting of synthetically glycosylated human placental glucocerebrosidase

Human placental β-glucocerebrosidase modified by covalent attachment of N 2-{ N 2, N 6-bis[3-(α- d-mannopyranosylthio)propionyl]- l-lysyl}- N 6-[3-(α- d-mannopyr-anosylthio) propionyl]- l-lysine was administered to rats by intravenous injection. Comparison of enzyme distribution in isolated liver cell populations indicates an increase in enzyme-specific activity of 18-fold in nonparenchymal cells and only 1.5-fold to hepatocytes compared to uninjected control animals. This macrophage-specific delivery of an active lysosomal enzyme has potential for application in enzyme replacement trials.