DATE CREATED: Dec 10, 2008
ACTION PLAN
PROBLEMS IDENTIFIED (PI) / OUTSIDE SKILL REQUIRED (OSR) / RESOLVED (R)
The chance of presence of ligands on the
surface of the particles
PAPER TITLE
A) Background
B) Specific Aims
C) General Experimental Approach (Design etc)
D) Design Pitfalls and alternatives
E) Potential Figures
F) Future Directions
Ligand-decorated Shape-specific Nanoparticles for Treatment of Resistant Breast Cancer
A) BACKGROUND:
Breast carcinoma is one of the most common malignant tumours and the second leading cause of cancer death in American women. Chemotherapy plays an important role in the management of patients with breast carcinoma. However, the treatment response rate is low and cases of complete remission are rare due to the development of multidrug resistance (MDR). MDR is the phenomenon of simultaneous resistance to many structurally unrelated cytotoxic agents, which is one of the most formidable challenges in the field of cancer therapy. A common mechanism of MDR is the active export of drug from cells by the overexpression of P-glycoprotein (P-gp) and other ATP-binding cassette (ABC) transporters. High dose chemotherapy and/or co-administration of chemosensitizers with anticancer drugs have been tried to bypass MDR in cell culture methods and clinically, but without success due to their severe adverse effects. Nanocarrier systems such as nanoparticles (NPs), liposomes, polymeric micelles and drug-polymer conjugates have been developed to prevent premature drug degradation; achieve effective site-specific/targeted delivery and reduce side effects of the drug. Such nanocarriers have shown promising in vitro results in reversing MDR in various tumour models. This was attributed to their endocytic uptake by cells, releasing the drug intracellularly. Hence, nanocarriers specifically targeted to such drug transporter proteins seem an attractive option to overcome MDR subject to the optimization of design parameters to achieve tumour-specific biodistribution and favourable intracellular trafficking.
Research in this area has so far focussed on the size, material chemistry, and particle surface characteristics for their fabrication. However, recent reports clearly suggest that particle shape could play significant role in determination of biodistribution, intracellular internalization and intracellular trafficking of these nanocarriers. Until recently, particle shape has been an unexplored area of research in drug delivery due to our inability to reliably synthesize nano or microparticle carriers with precise and pre-designed geometry. However, direct extension of lithographic techniques to drug delivery has opened new avenues to precisely control critical design parameters such as size, shape, type of biological agents and surface properties of these nanocarriers. Indeed, recent papers have shown that the intracellular uptake of these particles was dependent on their shape apart from size.
Development of better targeted therapies for breast carcinoma needs multidisciplinary approach at the level of engineering, microfluidics, materials science, drug delivery and cell biology. The major aim of this project is to develop and optimize size, shape-specific, biodegradable, biocompatible NPs targeted to multidrug resistant breast cancer cells.
B) SPECIFIC AIMS
Aim 1: To synthesize biodegradable polymers based on polyesters with/without the surface grafted chemosensitizers;
Aim 2: To develop specific master templates and elastic molds using imprint lithographic technique for fabrication of NPs in the size range of 50-200 nm of varying shapes and aspect ratios (spherical/conical/cylindrical);
Aim 3: To characterize and evaluate intracellular trafficking of size and shape-specific NPs with different surface chemistry (50-200 nm)
Aim 4: To determine efficacy, mechanism as well as the role of size, shape and surface chemistry on the intracellular uptake and trafficking of fabricated NPs by sensitive and resistant breast cancer cell lines
C) GENERAL EXPERIMENTAL APPROACH
Specific aim # 1: Synthesis of preformed biodegradable polymers based on polyesters with/without the surface grafted chemosensitizers
· Task 1: Synthesis and characterization of biodegradable polylactide-based polymers with pendent –COOH groups
· Task 2: Selection, preparation and characterization of various ligands to be grafted on these polymers
· Task 3: Grafting of modified ligands on PLA polymers with pendent –COOH groups and characterization of synthesized polymers
· Task 4: Evaluation of biocompatibility of synthesized polymer library in sensitive and resistant breast cancer cells using cell-based assays
Specific aim # 2: Development of specific master templates and elastic molds using imprint lithographic technique for fabrication of NPs in the size range of 50-200 nm of varying shapes (spherical/conical/cylindrical)
Silicon master templates and corresponding elastic molds of various shapes will be designed and optimized using the expertise in the lab of Dr. Khademhosseini.
· Task 1: Development of silicon master templates of various shapes (spherical/conical/cylindrical) and sizes (50, 100, 150, 200 nm)
· Task 2: Development and optimization of photocurable perfluoropolyether (PFPE) elastic molds to cast the shape and size-specific NPs
Specific aim # 3: Preparation, characterization and evaluation of intracellular trafficking of size and shape-specific NPs with different surface chemistry (50-200 nm)
Here, polymers grafted with targeted ligands will be used for NP synthesis. This work in sensitive and resistant cell lines will enable to primarily select most efficient particle size in each series of shapes. At the same time, evaluation of cytotoxic efficacy will give preliminary data on the most effective targeting ligand.
Specific aim # 4: In vitro evaluation of mechanism as well as role of size, shape on the intracellular uptake and trafficking of fabricated NPs by sensitive and resistant breast cancer cell lines
Last part of this project will mainly focus on the detailed understanding of cellular and mechanistic pathways involved in the trafficking and mechanism of uptake of these NPs. Particle series (based on size, shape and surface chemistry) showing best results from specific aim # 3 will be further compared for their uptake. At the same time, evaluation will be carried out to understand mechanism of their trafficking, intracellular co-localization and inhibitory role on drug transporters using cell-based assays and confocal microscopy.
D) DESIGN PITFALLS AND ALTERNATIVES
E) POTENTIAL FIGURES FOR PAPER
F) FUTURE DIRECTIONS