... After locating at a tumour site through the EPR effect, the outer phospholipid shell releases... more ... After locating at a tumour site through the EPR effect, the outer phospholipid shell releases ananti-angiogenesis agent, and the inner ... Recently, a cancer therapy was developed based on absorption of NIR light by nanoshells, resulting in rapid localized heating to selectively kill ...
Nanoparticle-based drug delivery systems have been designed to treat various diseases. However, m... more Nanoparticle-based drug delivery systems have been designed to treat various diseases. However, many problems remain, such as inadequate tumor targeting and poor therapeutic outcomes. To overcome these obstacles, cell-based drug delivery systems have been developed. Candidates for cell-mediated drug delivery include blood cells, immune cells, and stem cells with innate tumor tropism and low immunogenicity; they act as a disguise to deliver the therapeutic payload. In drug delivery systems, therapeutic agents are encapsulated intracellularly or attached to the surface of the plasma membrane and transported to the desired site. Here, we review the pros and cons of cell-based therapies and discuss their homing mechanisms in the tumor microenvironment. In addition, different strategies to load therapeutic agents inside or on the surface of circulating cells and the current applications for a wide range of disease treatments are summarized.
Background The receptor tyrosine kinase (RTK) epidermal growth factor receptor (EGFR) is overexpr... more Background The receptor tyrosine kinase (RTK) epidermal growth factor receptor (EGFR) is overexpressed and an important therapeutic target in Head and Neck cancer (HNC). Cetuximab is currently the only EGFR-targeting agent approved by the FDA for treatment of HNC; however, intrinsic and acquired resistance to cetuximab is a major problem in the clinic. Our lab previously reported that AXL leads to cetuximab resistance via activation of HER3. In this study, we investigate the connection between AXL, HER3, and neuregulin1 (NRG1) gene expression with a focus on understanding how their interdependent signaling promotes resistance to cetuximab in HNC. Methods Plasmid or siRNA transfections and cell-based assays were conducted to test cetuximab sensitivity. Quantitative PCR and immunoblot analysis were used to analyze gene and protein expression levels. Seven HNC patient-derived xenografts (PDXs) were evaluated for protein expression levels. Results We found that HER3 expression was neces...
Interleukin-35 (IL-35) is an immunosuppressive cytokine composed of Epstein-Barr-virus-induced pr... more Interleukin-35 (IL-35) is an immunosuppressive cytokine composed of Epstein-Barr-virus-induced protein 3 (Ebi3) and IL-12α chain (p35) subunits, yet the forms that IL-35 assume and its role in peripheral tolerance remain elusive. We induce CBA-specific, IL-35-producing T regulatory (Treg) cells in Treg Ebi3WT C57BL/6 reporter mice and identify IL-35 producers by expression of *
Detection of circulating tumor cells (CTCs) relying on their expression of epithelial cell marker... more Detection of circulating tumor cells (CTCs) relying on their expression of epithelial cell markers, such as epithelial cell adhesion molecule (EpCAM), has been commonly used. However, this approach unlikely captures CTCs that have undergone the process of epithelial-mesenchymal transition (EMT). In this study, we have induced EMT of in vitro prostate (PCa) and breast cancer (BCa) cell lines by treatment of transforming growth factor beta 1 (TGFβ 1), a pleiotropic cytokine with transition-regulating activities. We found that the TGFβ 1-treated, post-EMT cells exhibited up to a 45% reduction in binding affinity to antibodies against EpCAM (aEpCAM). To overcome this limitation, we designed our capture platform that integrates a unique combination of biomimetic cell rolling, dendrimer-mediated multivalent binding, and antibody cocktails of aEpCAM/aEGFR/aHER-2. Our capture surfaces resulted in up to 98% capture efficiency of post-EMT cells from mixtures of TGFβ 1-treated and untreated cancer cells spiked in culture media and *
Nanoparticles have shown great promise in the treatment of cancer, with a demonstrated potential ... more Nanoparticles have shown great promise in the treatment of cancer, with a demonstrated potential in targeted drug delivery. Among a myriad of nanocarriers that have been recently developed, dendrimers have attracted a great deal of scientific interests due to their unique chemical and structural properties that allow for precise engineering of their characteristics. Despite this, the clinical translation of dendrimers has been hindered due to their drawbacks, such as scale-up issues, rapid systemic elimination, inefficient tumor accumulation, and limited drug loading. In order to overcome these limitations, a series of reengineered dendrimers have been recently introduced using various approaches, including: i) modifications of structure and surfaces; ii) integration with linear polymers; and iii) hybridization with other types of nanocarriers. Chemical modifications and surface engineering have tailored dendrimers to improve their pharmacokinetics and tissue permeation. Copolymerization of dendritic polymers with linear polymers has resulted in various amphiphilic copolymers with self-assembly capabilities and improved drug loading efficiencies. Hybridization with other nanocarriers integrates advantageous characteristics of both systems, which includes prolonged plasma circulation times and enhanced tumor targeting. This review provides a comprehensive summary of the newly emerging drug delivery systems that involve reengineering of dendrimers in an effort to precisely control their nano-bio interactions, mitigating their inherent weaknesses.
Journal of controlled release : official journal of the Controlled Release Society, Jan 10, 2014
Nanoparticle (NP)-based drug delivery platforms have received a great deal of attention over the ... more Nanoparticle (NP)-based drug delivery platforms have received a great deal of attention over the past two decades for their potential in targeted cancer therapies. Despite the promises, passive targeting approaches utilizing relatively larger NPs (typically 50-200nm in diameter) allow for passive tumor accumulation, but hinder efficient intratumoral penetration. Conversely, smaller, actively targeted NPs (<20nm in diameter) penetrate well into the tumor mass, but are limited by their rapid systemic elimination. To overcome these limitations, we have designed a multi-scale hybrid NP platform that loads smaller poly(amidoamine) (PAMAM) dendrimers (~5nm in diameter) into larger poly(ethylene glycol)-b-poly(D,L-lactide) (PEG-PLA) NPs (~70nm). A biodistribution study in healthy mice revealed that the hybrid NPs circulated longer than free dendrimers and were mostly cleared by macrophages in the liver and spleen, similar to the in vivo behavior of PEG-PLA NPs. When injected intravenous...
Polycationic organic nanoparticles are shown to disrupt model biological membranes and living cel... more Polycationic organic nanoparticles are shown to disrupt model biological membranes and living cell membranes at nanomolar concentrations. The degree of disruption is shown to be related to nanoparticle size and charge as well as to the phase, fluid liquid crystalline or gel, of the biological membrane. Disruption events on model membranes have been directly imaged using scanning probe microsopy whereas disruption events on living cells have been analyzed using cytosolic enzyme leakage assays, dye diffusion assays, and fluorescence microscopy.
Circulating tumor cells (CTCs) have received a great deal of scientific and clinical attention as... more Circulating tumor cells (CTCs) have received a great deal of scientific and clinical attention as a biomarker for diagnosis and prognosis of many types of cancer. Given their potential significance in clinics, a variety of detection methods, utilizing the recent advances in nanotechnology and microfluidics, have been introduced in an effort of achieving clinically significant detection of CTCs. However, effective detection and isolation of CTCs still remain a tremendous challenge due to their extreme rarity and phenotypic heterogeneity. Among many approaches that are currently under development, this review paper focuses on a unique, promising approach that takes advantages of naturally occurring processes achievable through application of nanotechnology to realize significant improvement in sensitivity and specificity of CTC capture. We provide an overview of successful outcome of this biomimetic CTC capture system in detection of tumor cells from in vitro, in vivo, and clinical pi...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Although circulating cell-free DNA (cfDNA) is a promising biomarker for the diagnosis and prognos... more Although circulating cell-free DNA (cfDNA) is a promising biomarker for the diagnosis and prognosis of various tumors, clinical correlation of cfDNA with gastric cancer has not been fully understood. To address this, we developed a highly sensitive cfDNA capture system by integrating polydopamine (PDA) and silica. PDA-silica hybrids incorporated different molecular interactions to a single system, enhancing cfDNA capture by 1.34-fold compared to the conventional silica-based approach (p = 0.001), which was confirmed using cell culture supernatants. A clinical study using human plasma samples revealed that the diagnostic accuracy of the new system to be superior than the commercially available cfDNA kit, as well as other serum antigen tests. Among the cancer patients, plasma cfDNA levels exhibited a good correlation with the size of a tumor. cfDNA was also predicative of distant metastasis, as the median cfDNA levels of metastatic cancer patients were ~60-fold higher than those witho...
Thermotherapy has demonstrated a potential to be an effective non-surgical technique to treat bre... more Thermotherapy has demonstrated a potential to be an effective non-surgical technique to treat breast cancer.
Invasion and metastasis of cancer directly related to human death have been associated with inter... more Invasion and metastasis of cancer directly related to human death have been associated with interactions among many different types of cells and three-dimensional (3D) tissue matrices. Precise mechanisms related to cancer invasion and metastasis still remain unknown due to their complexities. Development of tumor microenvironment-mimicking system could play a key role in understanding cancer environments and in elucidating the relating phenomena and their driving forces. Here we report a facile and novel platform of 3D cancer cell-clusters using human adipose-derived mesenchymal stem cells (hASCs) and breast cancer cells (MDA-MB-231) within a collagen gel matrix to show cancer invasion in the cell and extracellular matrix (ECM). Both clusters A (hASC only) and AC (hASC and MDA-MB-231) exhibited different behaviors and expressions of migration and invasion, as observed by the relating markers such as fibronectin, -SMA, and CXCR4. hASCs showed a protrusive migration from a cluster ce...
Detection of circulating tumor cells (CTCs) in blood has been extensively investigated to use the... more Detection of circulating tumor cells (CTCs) in blood has been extensively investigated to use them as a biomarker for the diagnosis and prognosis of various cancers. This review provides a comprehensive overview of recent advances in CTC detection achieved through application of microfluidic devices and the challenges that these promising technologies must overcome to be clinically impactful.
Drug-resistant tuberculosis (TB) has lent urgency to finding new drug leads with novel modes of a... more Drug-resistant tuberculosis (TB) has lent urgency to finding new drug leads with novel modes of action. A high-throughput screening campaign of >65,000 actinomycete extracts for inhibition of Mycobacterium tuberculosis viability identified ecumicin, a macrocyclic tridecapeptide that exerts potent, selective bactericidal activity against M. tuberculosis in vitro , including nonreplicating cells. Ecumicin retains activity against isolated multiple-drug-resistant (MDR) and extensively drug-resistant (XDR) strains of M. tuberculosis . The subcutaneous administration to mice of ecumicin in a micellar formulation at 20 mg/kg body weight resulted in plasma and lung exposures exceeding the MIC. Complete inhibition of M. tuberculosis growth in the lungs of mice was achieved following 12 doses at 20 or 32 mg/kg. Genome mining of lab-generated, spontaneous ecumicin-resistant M. tuberculosis strains identified the ClpC1 ATPase complex as the putative target, and this was confirmed by a drug ...
Accumulation of extracellular matrix (ECM) materials in the trabecular meshwork (TM) is believed ... more Accumulation of extracellular matrix (ECM) materials in the trabecular meshwork (TM) is believed to be a contributing factor to intraocular pressure (IOP) elevation, a risk factor/cause of primary open angle glaucoma, a major blinding disease. Matrix metalloproteinase-3 (MMP-3) is one of the proteinases that can effectively degrade ECM elements such as fibronectin, and MMP-3 delivery to the TM represents a promising approach for IOP reduction and treatment of glaucoma. In this study, we tested the feasibility of using polymeric microparticles to achieve a slow and sustained release of active MMP-3 to cultured human TM cells. β-Casein, with molecular weight (24 kDa) and hydrophobicity similar to those of the active MMP-3 fragment (19.2 kDa), was first employed as a model for initial testing. β-casein was encapsulated into poly(lactic-co-glycolic acid) (PLGA) microparticles using a double emulsion procedure at an encapsulation efficiency of approximately 45%. The PLGA microparticles were chosen given their biocompatibility and the proven capacity of sustained release of encapsulated molecules. The release test conducted in the culture medium showed a slow and sustained release of the protein over 20 days without a significant initial burst release. Active MMP-3 was subsequently encapsulated into PLGA microparticles with an encapsulation efficiency of approximately 50%. A bio-functional assay utilizing human TM cells was set up in which the reduction of fibronectin was used as an indicator of enzyme activity. It was observed that fibronectin staining was markedly reduced by the medium collected from MMP-3-microparticle-treated cultures compared to that from blank-and β-caseinmicroparticle controls, which was validated using a direct MMP-3 activity assay. The controlled release of MMP-3 from the microparticles resulted in sustained degradation of fibronectin up to 10 days. This proof-of-concept undertaking represents the first study on the controlled and sustained release of active MMP-3 to TM cells via encapsulation into PLGA microparticles as the potential treatment of glaucoma.
Organic-coated superparamagnetic iron oxide nanoparticles (OC-SPIONs) were synthesized and charac... more Organic-coated superparamagnetic iron oxide nanoparticles (OC-SPIONs) were synthesized and characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. OC-SPIONs were transferred from organic media into water using poly(amidoamine) dendrimers modified with 6-TAMRA fluorescent dye and folic acid molecules. The saturation magnetization of the resulting dendrimer-coated SPIONs (DC-SPIONs) was determined, using a superconducting quantum interference device, to be 60 emu/g Fe versus 90 emu/g Fe for bulk magnetite. Selective targeting of the DC-SPIONs to KB cancer cells in vitro was demonstrated and quantified using two distinct and complementary imaging modalities: UV-visible and X-ray fluorescence; confocal microscopy confirmed internalization. The results were consistent between the uptake distribution quantified by flow cytometry using 6-TAMRA UV-visible fluorescence intensity and the cellular iron content determined using Xray fluorescence microscopy.
Here we report a new method for multi-component protein patterning in a microchannel and also a t... more Here we report a new method for multi-component protein patterning in a microchannel and also a technique for improving immunoaffinity-based circulating tumor cell (CTC) capture by patterning regions of alternating adhesive proteins using the new method. The first of two proteins, antiepithelial cell adhesion molecule (anti-EpCAM), provides the specificity for CTC capture. The second, E-selectin, increases CTC capture under shear. Patterning regions with and without Eselectin allows captured leukocytes, which also bind E-selectin and are unwanted impurities in CTC isolation, to roll a short distance and detach from the capture surface. This reduces leukocyte capture by up to 82%. The patterning is combined with a leukocyte elution step in which a calcium chelating buffer effectively deactivates E-selectin so that leukocytes may be rinsed away 60% more efficiently than with a buffer containing calcium. The alternating patterning of this biomimetic protein combination, used in conjunction with the elution step, reduce capture of leukocytes while maintaining a high tumor capture efficiency that is up to 1.9 times higher than the tumor cell capture efficiency of a surface with only anti-EpCAM. The new patterning technique described here does not require mask alignment and can be used to spatially control the immobilization of any 2 proteins or protein mixtures inside a sealed microfluidic channel.
... After locating at a tumour site through the EPR effect, the outer phospholipid shell releases... more ... After locating at a tumour site through the EPR effect, the outer phospholipid shell releases ananti-angiogenesis agent, and the inner ... Recently, a cancer therapy was developed based on absorption of NIR light by nanoshells, resulting in rapid localized heating to selectively kill ...
Nanoparticle-based drug delivery systems have been designed to treat various diseases. However, m... more Nanoparticle-based drug delivery systems have been designed to treat various diseases. However, many problems remain, such as inadequate tumor targeting and poor therapeutic outcomes. To overcome these obstacles, cell-based drug delivery systems have been developed. Candidates for cell-mediated drug delivery include blood cells, immune cells, and stem cells with innate tumor tropism and low immunogenicity; they act as a disguise to deliver the therapeutic payload. In drug delivery systems, therapeutic agents are encapsulated intracellularly or attached to the surface of the plasma membrane and transported to the desired site. Here, we review the pros and cons of cell-based therapies and discuss their homing mechanisms in the tumor microenvironment. In addition, different strategies to load therapeutic agents inside or on the surface of circulating cells and the current applications for a wide range of disease treatments are summarized.
Background The receptor tyrosine kinase (RTK) epidermal growth factor receptor (EGFR) is overexpr... more Background The receptor tyrosine kinase (RTK) epidermal growth factor receptor (EGFR) is overexpressed and an important therapeutic target in Head and Neck cancer (HNC). Cetuximab is currently the only EGFR-targeting agent approved by the FDA for treatment of HNC; however, intrinsic and acquired resistance to cetuximab is a major problem in the clinic. Our lab previously reported that AXL leads to cetuximab resistance via activation of HER3. In this study, we investigate the connection between AXL, HER3, and neuregulin1 (NRG1) gene expression with a focus on understanding how their interdependent signaling promotes resistance to cetuximab in HNC. Methods Plasmid or siRNA transfections and cell-based assays were conducted to test cetuximab sensitivity. Quantitative PCR and immunoblot analysis were used to analyze gene and protein expression levels. Seven HNC patient-derived xenografts (PDXs) were evaluated for protein expression levels. Results We found that HER3 expression was neces...
Interleukin-35 (IL-35) is an immunosuppressive cytokine composed of Epstein-Barr-virus-induced pr... more Interleukin-35 (IL-35) is an immunosuppressive cytokine composed of Epstein-Barr-virus-induced protein 3 (Ebi3) and IL-12α chain (p35) subunits, yet the forms that IL-35 assume and its role in peripheral tolerance remain elusive. We induce CBA-specific, IL-35-producing T regulatory (Treg) cells in Treg Ebi3WT C57BL/6 reporter mice and identify IL-35 producers by expression of *
Detection of circulating tumor cells (CTCs) relying on their expression of epithelial cell marker... more Detection of circulating tumor cells (CTCs) relying on their expression of epithelial cell markers, such as epithelial cell adhesion molecule (EpCAM), has been commonly used. However, this approach unlikely captures CTCs that have undergone the process of epithelial-mesenchymal transition (EMT). In this study, we have induced EMT of in vitro prostate (PCa) and breast cancer (BCa) cell lines by treatment of transforming growth factor beta 1 (TGFβ 1), a pleiotropic cytokine with transition-regulating activities. We found that the TGFβ 1-treated, post-EMT cells exhibited up to a 45% reduction in binding affinity to antibodies against EpCAM (aEpCAM). To overcome this limitation, we designed our capture platform that integrates a unique combination of biomimetic cell rolling, dendrimer-mediated multivalent binding, and antibody cocktails of aEpCAM/aEGFR/aHER-2. Our capture surfaces resulted in up to 98% capture efficiency of post-EMT cells from mixtures of TGFβ 1-treated and untreated cancer cells spiked in culture media and *
Nanoparticles have shown great promise in the treatment of cancer, with a demonstrated potential ... more Nanoparticles have shown great promise in the treatment of cancer, with a demonstrated potential in targeted drug delivery. Among a myriad of nanocarriers that have been recently developed, dendrimers have attracted a great deal of scientific interests due to their unique chemical and structural properties that allow for precise engineering of their characteristics. Despite this, the clinical translation of dendrimers has been hindered due to their drawbacks, such as scale-up issues, rapid systemic elimination, inefficient tumor accumulation, and limited drug loading. In order to overcome these limitations, a series of reengineered dendrimers have been recently introduced using various approaches, including: i) modifications of structure and surfaces; ii) integration with linear polymers; and iii) hybridization with other types of nanocarriers. Chemical modifications and surface engineering have tailored dendrimers to improve their pharmacokinetics and tissue permeation. Copolymerization of dendritic polymers with linear polymers has resulted in various amphiphilic copolymers with self-assembly capabilities and improved drug loading efficiencies. Hybridization with other nanocarriers integrates advantageous characteristics of both systems, which includes prolonged plasma circulation times and enhanced tumor targeting. This review provides a comprehensive summary of the newly emerging drug delivery systems that involve reengineering of dendrimers in an effort to precisely control their nano-bio interactions, mitigating their inherent weaknesses.
Journal of controlled release : official journal of the Controlled Release Society, Jan 10, 2014
Nanoparticle (NP)-based drug delivery platforms have received a great deal of attention over the ... more Nanoparticle (NP)-based drug delivery platforms have received a great deal of attention over the past two decades for their potential in targeted cancer therapies. Despite the promises, passive targeting approaches utilizing relatively larger NPs (typically 50-200nm in diameter) allow for passive tumor accumulation, but hinder efficient intratumoral penetration. Conversely, smaller, actively targeted NPs (<20nm in diameter) penetrate well into the tumor mass, but are limited by their rapid systemic elimination. To overcome these limitations, we have designed a multi-scale hybrid NP platform that loads smaller poly(amidoamine) (PAMAM) dendrimers (~5nm in diameter) into larger poly(ethylene glycol)-b-poly(D,L-lactide) (PEG-PLA) NPs (~70nm). A biodistribution study in healthy mice revealed that the hybrid NPs circulated longer than free dendrimers and were mostly cleared by macrophages in the liver and spleen, similar to the in vivo behavior of PEG-PLA NPs. When injected intravenous...
Polycationic organic nanoparticles are shown to disrupt model biological membranes and living cel... more Polycationic organic nanoparticles are shown to disrupt model biological membranes and living cell membranes at nanomolar concentrations. The degree of disruption is shown to be related to nanoparticle size and charge as well as to the phase, fluid liquid crystalline or gel, of the biological membrane. Disruption events on model membranes have been directly imaged using scanning probe microsopy whereas disruption events on living cells have been analyzed using cytosolic enzyme leakage assays, dye diffusion assays, and fluorescence microscopy.
Circulating tumor cells (CTCs) have received a great deal of scientific and clinical attention as... more Circulating tumor cells (CTCs) have received a great deal of scientific and clinical attention as a biomarker for diagnosis and prognosis of many types of cancer. Given their potential significance in clinics, a variety of detection methods, utilizing the recent advances in nanotechnology and microfluidics, have been introduced in an effort of achieving clinically significant detection of CTCs. However, effective detection and isolation of CTCs still remain a tremendous challenge due to their extreme rarity and phenotypic heterogeneity. Among many approaches that are currently under development, this review paper focuses on a unique, promising approach that takes advantages of naturally occurring processes achievable through application of nanotechnology to realize significant improvement in sensitivity and specificity of CTC capture. We provide an overview of successful outcome of this biomimetic CTC capture system in detection of tumor cells from in vitro, in vivo, and clinical pi...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Although circulating cell-free DNA (cfDNA) is a promising biomarker for the diagnosis and prognos... more Although circulating cell-free DNA (cfDNA) is a promising biomarker for the diagnosis and prognosis of various tumors, clinical correlation of cfDNA with gastric cancer has not been fully understood. To address this, we developed a highly sensitive cfDNA capture system by integrating polydopamine (PDA) and silica. PDA-silica hybrids incorporated different molecular interactions to a single system, enhancing cfDNA capture by 1.34-fold compared to the conventional silica-based approach (p = 0.001), which was confirmed using cell culture supernatants. A clinical study using human plasma samples revealed that the diagnostic accuracy of the new system to be superior than the commercially available cfDNA kit, as well as other serum antigen tests. Among the cancer patients, plasma cfDNA levels exhibited a good correlation with the size of a tumor. cfDNA was also predicative of distant metastasis, as the median cfDNA levels of metastatic cancer patients were ~60-fold higher than those witho...
Thermotherapy has demonstrated a potential to be an effective non-surgical technique to treat bre... more Thermotherapy has demonstrated a potential to be an effective non-surgical technique to treat breast cancer.
Invasion and metastasis of cancer directly related to human death have been associated with inter... more Invasion and metastasis of cancer directly related to human death have been associated with interactions among many different types of cells and three-dimensional (3D) tissue matrices. Precise mechanisms related to cancer invasion and metastasis still remain unknown due to their complexities. Development of tumor microenvironment-mimicking system could play a key role in understanding cancer environments and in elucidating the relating phenomena and their driving forces. Here we report a facile and novel platform of 3D cancer cell-clusters using human adipose-derived mesenchymal stem cells (hASCs) and breast cancer cells (MDA-MB-231) within a collagen gel matrix to show cancer invasion in the cell and extracellular matrix (ECM). Both clusters A (hASC only) and AC (hASC and MDA-MB-231) exhibited different behaviors and expressions of migration and invasion, as observed by the relating markers such as fibronectin, -SMA, and CXCR4. hASCs showed a protrusive migration from a cluster ce...
Detection of circulating tumor cells (CTCs) in blood has been extensively investigated to use the... more Detection of circulating tumor cells (CTCs) in blood has been extensively investigated to use them as a biomarker for the diagnosis and prognosis of various cancers. This review provides a comprehensive overview of recent advances in CTC detection achieved through application of microfluidic devices and the challenges that these promising technologies must overcome to be clinically impactful.
Drug-resistant tuberculosis (TB) has lent urgency to finding new drug leads with novel modes of a... more Drug-resistant tuberculosis (TB) has lent urgency to finding new drug leads with novel modes of action. A high-throughput screening campaign of >65,000 actinomycete extracts for inhibition of Mycobacterium tuberculosis viability identified ecumicin, a macrocyclic tridecapeptide that exerts potent, selective bactericidal activity against M. tuberculosis in vitro , including nonreplicating cells. Ecumicin retains activity against isolated multiple-drug-resistant (MDR) and extensively drug-resistant (XDR) strains of M. tuberculosis . The subcutaneous administration to mice of ecumicin in a micellar formulation at 20 mg/kg body weight resulted in plasma and lung exposures exceeding the MIC. Complete inhibition of M. tuberculosis growth in the lungs of mice was achieved following 12 doses at 20 or 32 mg/kg. Genome mining of lab-generated, spontaneous ecumicin-resistant M. tuberculosis strains identified the ClpC1 ATPase complex as the putative target, and this was confirmed by a drug ...
Accumulation of extracellular matrix (ECM) materials in the trabecular meshwork (TM) is believed ... more Accumulation of extracellular matrix (ECM) materials in the trabecular meshwork (TM) is believed to be a contributing factor to intraocular pressure (IOP) elevation, a risk factor/cause of primary open angle glaucoma, a major blinding disease. Matrix metalloproteinase-3 (MMP-3) is one of the proteinases that can effectively degrade ECM elements such as fibronectin, and MMP-3 delivery to the TM represents a promising approach for IOP reduction and treatment of glaucoma. In this study, we tested the feasibility of using polymeric microparticles to achieve a slow and sustained release of active MMP-3 to cultured human TM cells. β-Casein, with molecular weight (24 kDa) and hydrophobicity similar to those of the active MMP-3 fragment (19.2 kDa), was first employed as a model for initial testing. β-casein was encapsulated into poly(lactic-co-glycolic acid) (PLGA) microparticles using a double emulsion procedure at an encapsulation efficiency of approximately 45%. The PLGA microparticles were chosen given their biocompatibility and the proven capacity of sustained release of encapsulated molecules. The release test conducted in the culture medium showed a slow and sustained release of the protein over 20 days without a significant initial burst release. Active MMP-3 was subsequently encapsulated into PLGA microparticles with an encapsulation efficiency of approximately 50%. A bio-functional assay utilizing human TM cells was set up in which the reduction of fibronectin was used as an indicator of enzyme activity. It was observed that fibronectin staining was markedly reduced by the medium collected from MMP-3-microparticle-treated cultures compared to that from blank-and β-caseinmicroparticle controls, which was validated using a direct MMP-3 activity assay. The controlled release of MMP-3 from the microparticles resulted in sustained degradation of fibronectin up to 10 days. This proof-of-concept undertaking represents the first study on the controlled and sustained release of active MMP-3 to TM cells via encapsulation into PLGA microparticles as the potential treatment of glaucoma.
Organic-coated superparamagnetic iron oxide nanoparticles (OC-SPIONs) were synthesized and charac... more Organic-coated superparamagnetic iron oxide nanoparticles (OC-SPIONs) were synthesized and characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. OC-SPIONs were transferred from organic media into water using poly(amidoamine) dendrimers modified with 6-TAMRA fluorescent dye and folic acid molecules. The saturation magnetization of the resulting dendrimer-coated SPIONs (DC-SPIONs) was determined, using a superconducting quantum interference device, to be 60 emu/g Fe versus 90 emu/g Fe for bulk magnetite. Selective targeting of the DC-SPIONs to KB cancer cells in vitro was demonstrated and quantified using two distinct and complementary imaging modalities: UV-visible and X-ray fluorescence; confocal microscopy confirmed internalization. The results were consistent between the uptake distribution quantified by flow cytometry using 6-TAMRA UV-visible fluorescence intensity and the cellular iron content determined using Xray fluorescence microscopy.
Here we report a new method for multi-component protein patterning in a microchannel and also a t... more Here we report a new method for multi-component protein patterning in a microchannel and also a technique for improving immunoaffinity-based circulating tumor cell (CTC) capture by patterning regions of alternating adhesive proteins using the new method. The first of two proteins, antiepithelial cell adhesion molecule (anti-EpCAM), provides the specificity for CTC capture. The second, E-selectin, increases CTC capture under shear. Patterning regions with and without Eselectin allows captured leukocytes, which also bind E-selectin and are unwanted impurities in CTC isolation, to roll a short distance and detach from the capture surface. This reduces leukocyte capture by up to 82%. The patterning is combined with a leukocyte elution step in which a calcium chelating buffer effectively deactivates E-selectin so that leukocytes may be rinsed away 60% more efficiently than with a buffer containing calcium. The alternating patterning of this biomimetic protein combination, used in conjunction with the elution step, reduce capture of leukocytes while maintaining a high tumor capture efficiency that is up to 1.9 times higher than the tumor cell capture efficiency of a surface with only anti-EpCAM. The new patterning technique described here does not require mask alignment and can be used to spatially control the immobilization of any 2 proteins or protein mixtures inside a sealed microfluidic channel.
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