Sharad Mangal

Synthesis, characterization and evaluation of novel triblock copolymer based nanoparticles for vaccine delivery against hepatitis B

Poly lactic acid (PLA) is one of widely used biodegradable polymer in vaccine delivery. However, the use is restricted due to hydrophobic nature and generation of acidic microenvironment upon its degradation, rendering it unfavorable to the encapsulated antigen. In the present study we have synthesized PEG derivatized block copolymers of PLA for development of nanoparticles encapsulating HBsAg for mucosal vaccination against hepatitis B. The copolymers of compositions AB, ABA and BAB (PLA as A-block and PEG as B-block) were synthesized and characterized by 1H NMR spectroscopy and gel permeation chromatography. Nanoparticles were characterized to determine the effect of copolymer. Among all, BAB produced nanoparticles of smallest size and lowest zeta potential, suggesting highest PEG density on their surface. The in vitro release experiments were performed in PBS (pH7.4). SDS-PAGE analysis confirmed the structural stability and integrity of the released antigen. Results were compared for immunogenicity with plain PLA nanoparticles and conventional alum-HBsAg based vaccine. BAB nanoparticles produced better humoral response as compared to other polymeric nanoparticles. The extent of humoral response obtained in single dose of BAB nanoparticles was comparable to the response produced by alum based vaccine (which received a booster dose). Block copolymeric nanoparticles also produced better sIgA level at all local and distal mucosal sites as compare of PLA nanoparticles, where alum based formulation failed to give any considerable response. Additionally, IgG1 and IgG2a isotype were determined to confirm the T(H)1/T(H)2 mixed immune response. These data demonstrate the potential of BAB nanoparticles as mucosal vaccine delivery system capable of eliciting high and prolonged immune response.

Development and characterization of surface modified PLGA nanoparticles for nasal vaccine delivery: Effect of mucoadhesive coating on antigen uptake and immune adjuvant activity

In this study, the efficacy of mucoadhesive polymers, i.e., chitosan and glycol chitosan as a mucoadhesive coating material in nasal vaccine delivery was investigated. The Hepatitis B surface Antigen (HBsAg) encapsulated PLGA, chitosan coated PLGA (C-PLGA), and Glycol chitosan coated PLGA (GC-PLGA) nanoparticles (NPs) were prepared. The formulations were characterized for particle size, shape, surface charge, and entrapment efficiency. The mucoadhesive ability of coated and non-coated NPs was determined using in vitro mucoadhesion and nasal clearance test. In addition, the systemic uptake and bio-distribution were also evaluated to understand the fate of NPs following nasal delivery. The immuno-adjuvant ability of various formulations was compared by measuring specific antibody titer in serum and secretory. The results indicated that PLGA NPs exhibit negative surface charge, whereas C-PLGA and GC-PLGA NPs exhibited positive surface charge. The GC-PLGA NPs demonstrated lower clearance and better local and systemic uptake compared to chitosan coated and uncoated PLGA NPs. In vivo immunogenicity studies indicated that GC-PLGA NPs could induce significantly higher systemic and mucosal immune response compared to PLGA and C-PLGA NPs. In conclusion, GC-PLGA NPs could be a promising carrier adjuvant for the nasal vaccine delivery for inducing a potent immune response at mucosal surface(s) and systemic circulation.

Evaluation of mucoadhesive PLGA microparticles for nasal immunization.

In this study, hepatitis B surface antigen (HBsAg) loaded poly(lactic-co-glycolic acid) (PLGA) microparticles were prepared and coated with chitosan and trimethyl chitosan (TMC) to evaluate the effect of coating material for nasal vaccine delivery. The developed formulations were characterized for size, zeta potential, entrapment efficiency, and mucin adsorption ability. Plain PLGA microparticles demonstrated negative zeta potential. However, coated microparticles showed higher positive zeta potential. Results indicated that TMC microparticles demonstrated substantially higher mucin adsorption when compared to chitosan-coated microparticles and plain PLGA microparticles. The coated and uncoated microparticles showed deposition in nasal-associated lymphoid tissue under fluorescence microscopy. The coated and uncoated microparticles were then administered intranasally to mice. Immune-adjuvant effect was determined on the basis of specific antibody titer observed in serum and secretions using enzyme-linked immunosorbent assay. It was observed that coated particles showed a markedly increased anti-HBsAg titer as compared to plain PLGA microparticles, but the results were more pronounced with the TMC-coated PLGA microparticles.

Pharmaceutical and immunological evaluation of mucoadhesive nanoparticles based delivery system(s) administered Intranasally

Tri-methyl chitosan synthesis accompanies polymer chain scission, which may affect the carrier and adjuvant properties of the polymer. The main objective of this study was to synthesize the tri-methylated chitosan using mild (TMC-M) and conventional (TMC) method and compare their efficacy as nasal vaccine delivery vehicle. During in vitro studies TMC-M nanoparticles showed the lowest nasal clearance rate when compared with chitosan (CS) and TMC nanoparticles. The immunogenicity of nanoparticles based delivery system(s) was assessed by measuring anti-HBsAg antibody titer in mice serum and secretions after intranasal administration. The alum based HBsAg vaccine injected subcutaneously was used as positive control. Results indicated that alum based HBsAg induced strong humoral but negligible mucosal immunity. However, TMC-M nanoparticles induced stronger immune response at both of the fronts as compared to generated by CS or TMC nanoparticles. Present study demonstrates that TMC-M can be a better carrier adjuvant for nasal subunit vaccines.

Recent advances in mucosal delivery of vaccines: role of mucoadhesive/biodegradable polymeric carriers

Importance of the field: The mucosal delivery of vaccines provides the basis for induction of humoral, cellular and mucosal immune responses against infectious diseases. The delivery of antigens to and through mucosal barriers always remains challenging due to adverse physiological conditions (pH and enzymes) and biological barriers created by tight epithelial junctions restricting transportation of macromolecules. Mucoadhesive and biodegradable polymers offer numerous advantages in therapeutic delivery of proteins/antigens particularly through the mucosal route by protecting antigens from degradation, increasing concentration of antigen in the vicinity of mucosal tissue for better absorption, extending their residence time in the body and/or targeting them to sites of antigen uptake. Furthermore, antigen can be delivered more effectively to the antigen presenting cells by anchoring the ligand having affinity on the surface of carrier for the receptors present on the mucosal epithelial cells. Areas covered in this review: The present review covers various polymeric carriers, which allow the possibility of modification and manipulation of their properties, thereby, enhancing the effectiveness of mucosal vaccines. This article reviews the recent literature and patents in the field of vaccine delivery using mucoadhesive polymeric carriers. What the reader will gain: The reader will gain insights into various natural polymers, synthetic polymers and ligand derived polymeric carrier systems studied to enhance mucosal immunization. Take home message: Biodegradable polymeric carriers represent a promising approach for mucosal delivery of vaccine.

Relationship between surface concentration of L-leucine and bulk powder properties in spray dried formulations.

The amino acid L-leucine has been demonstrated to act as a lubricant and improve the dispersibility of otherwise cohesive fine particles. It was hypothesized that optimum surface L-leucine concentration is necessary to achieve optimal surface and bulk powder properties. Polyvinylpyrrolidone was spray dried with different concentration of L-leucine and the change in surface composition of the formulations was determined using X-ray photoelectron spectroscopy (XPS) and time of flight-secondary ion mass spectrometry (ToF-SIMS). The formulations were also subjected to powder X-ray diffraction analysis in order to understand the relationship between surface concentration and solid-state properties of L-leucine. In addition, the morphology, surface energy and bulk cohesion of spray dried formulations were also assessed to understand the relation between surface L-leucine concentration and surface and bulk properties. The surface concentration of L-leucine increased with higher feed concentrations and plateaued at about 10% L-leucine. Higher surface L-leucine concentration also resulted in the formation of larger L-leucine crystals and not much change in crystal size was noted above 10% L-leucine. A change in surface morphology of particles from spherical to increasingly corrugated was also observed with increasing surface l-leucine concentration. Specific collapsed/folded over particles were only seen in formulations with 10% or higher l-leucine feed concentration suggesting a change in particle surface formation process. In addition, bulk cohesion also reduced and approached a minimum with 10% L-leucine concentration. Thus, the surface concentration of L-leucine governs particle formation and optimum surface L-leucine concentration results in optimum surface and bulk powder properties.

RNA-based immunotherapy of cancer: role and therapeutic implications of dendritic cells.

Cancer immunotherapy aims at eliciting an immune response directed against tumor antigens to help fight off residual tumor cells and, thereby, improve the survival and quality of life of cancer patients. Different immunotherapeutic approaches share the use of dendritic cells (DCs) to present tumor-associated antigens to T lymphocytes. DCs are specialized for antigen presentation, and their immunogenicity leads to the induction of antigen-specific immune responses. Ex vivo-generated DCs can be loaded with antigens and re-infused to the patients or they can be used for the ex vivo expansion of anti-tumor lymphocytes. Alternatively, methods exist to target antigens in vivo without the need for ex vivo cell manipulations. DCs loaded ex vivo with RNA can be administered safely and might prove to be an asset for producing antigen-specific immune responses. Furthermore, these observations have led to clinical trials designed to investigate the immunological and clinical effects of RNA-pulsed DCs administered as a therapeutic vaccine in cancer patients. However, selection of the antigen, methods for introducing tumor-associated antigens into MHC class I and II processing pathways, methods for isolation and activation of DCs and route of administration are the parameters to be considered for designing and conducting clinical trials with phenotypically altered DCs. The enhanced RNA transfection efficiency and DC maturation would further improve antigen processing and presentation and T-cell costimulation, resulting in the induction of heightened anti-tumor immune responses. Therefore, DCs pulsed with RNA continues to hold promise for cellular immunotherapy.

The role of physico-chemical and bulk characteristics of co-spray dried L-leucine and polyvinylpyrrolidone on glidant and binder properties in interactive mixtures

In this study, polyvinylpyrrolidone (PVP) was spray dried with l-leucine (PVP-Leu) to create a prototype multifunctional interactive excipient. The physico-chemical and bulk properties such as particle size, surface composition, surface energy and bulk cohesion of PVP-Leu was measured and compared against pure spray dried PVP (PVP-SD). The mixing behaviour of these excipients and their effect on flow and binder activity of paracetamol was assessed. The mean particle sizes of PVP-Leu PVP-SD and PVP were 2.5, 2.1 and 21.9μm, respectively. Surface composition characterization indicated that l-leucine achieved higher concentrations on the surface compared to the bulk of the PVP-Leu particles. The surface energy of PVP-Leu was significantly lower compared to PVP-SD. In addition, PVP-Leu exhibited a significantly lower bulk cohesion compared PVP-SD. The excipients were blended with paracetamol and qualitative characterization indicated that PVP-Leu blended more homogeneously with paracetamol compared to PVP-SD. Both PVP-Leu and PVP-SD then exhibited a significantly improved binder activity compared to PVP. The flow of the paracetamol was markedly improved with PVP-Leu while PVP-SD and PVP had negligible effect on its flow. This study reveals how physico-chemical and bulk properties of such prototype interactive excipients can play a key role in determining multi-factorial excipient performance.

Particle Engineering of Excipients for Direct Compression: Understanding the Role of Material Properties.

Tablets represent the preferred and most commonly dispensed pharmaceutical dosage form for administering active pharmaceutical ingredients (APIs). Minimizing the cost of goods and improving manufacturing output efficiency has motivated companies to use direct compression as a preferred method of tablet manufacturing. Excipients dictate the success of direct compression, notably by optimizing powder formulation compactability and flow, thus there has been a surge in creating excipients specifically designed to meet these needs for direct compression. Greater scientific understanding of tablet manufacturing coupled with effective application of the principles of material science and particle engineering has resulted in a number of improved direct compression excipients. Despite this, significant practical disadvantages of direct compression remain relative to granulation, and this is partly due to the limitations of direct compression excipients. For instance, in formulating high-dose APIs, a much higher level of excipient is required relative to wet or dry granulation and so tablets are much bigger. Creating excipients to enable direct compression of high-dose APIs requires the knowledge of the relationship between fundamental material properties and excipient functionalities. In this paper, we review the current understanding of the relationship between fundamental material properties and excipient functionality for direct compression.

Pulmonary delivery of nanoparticle chemotherapy for the treatment of lung cancers: challenges and opportunities

Lung cancer is the second most prevalent and the deadliest among all cancer types. Chemotherapy is recommended for lung cancers to control tumor growth and to prolong patient survival. Systemic chemotherapy typically has very limited efficacy as well as severe systemic adverse effects, which are often attributed to the distribution of anticancer drugs to non-targeted sites. In contrast, inhalation routes permit the delivery of drugs directly to the lungs providing high local concentrations that may enhance the anti-tumor effect while alleviating systemic adverse effects. Preliminary studies in animals and humans have suggested that most inhaled chemotherapies are tolerable with manageable pulmonary adverse effects, including cough and bronchospasm. Promoting the deposition of anticancer drugs in tumorous cells and minimizing access to healthy lung cells can further augment the efficacy and reduce the risk of local toxicities caused by inhaled chemotherapy. Sustained release and tumor localization characteristics make nanoparticle formulations a promising candidate for the inhaled delivery of chemotherapeutic agents against lung cancers. However, the physiology of respiratory tracts and lung clearance mechanisms present key barriers for the effective deposition and retention of inhaled nanoparticle formulations in the lungs. Recent research has focused on the development of novel formulations to maximize lung deposition and to minimize pulmonary clearance of inhaled nanoparticles. This article systematically reviews the challenges and opportunities for the pulmonary delivery of nanoparticle formulations for the treatment of lung cancers.