Dorn Research Institute

Science, United States

Dorn Research Institute

Science, United States

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Yang F.,University of South Carolina | Yang X.,University of South Carolina | Yang X.,Dorn Veterans Affairs Medical Center | Yang X.,Dorn Research Institute | And 7 more authors.
Biomicrofluidics | Year: 2010

Separation of colorectal cancer cells from other biological materials is important for stool-based diagnosis of colorectal cancer. In this paper, we use conventional dielectrophoresis in a microfluidic chip to manipulate and isolate HCT116 colorectal cancer cells. It is noticed that at a particular alternating current frequency band, the HCT116 cells are clearly deflected to a side channel from the main channel after the electric activation of an electrode pair. This motion caused by negative dielectrophoresis can be used to simply and rapidly separate cancer cells from other cells. In this manuscript, we report the chip design, flow conditions, dielectrophoretic spectrum of the cancer cells, and the enrichment factor of the colorectal cancer cells from other cells. © 2010 American Institute of Physics.


Yang F.,University of South Carolina | Yang X.,Dorn Research Institute | Jiang H.,GraceFlow Technology | Wang G.,University of South Carolina
Electrophoresis | Year: 2011

We have developed two new microfluidic cell sorters based on conventional negative dielectrophoresis (DEP) for continuous flow operations. The first is a cascade configuration sorter designed to increase purity of isolated target cell. The second has two staggered side channels in opposite side walls to increase sample throughput without compromising enrichment factor. Particles (carboxylate microspheres) of different sizes were first used to demonstrate the feasibility of the present DEP sorters for cell isolation. Then biological cells, i.e. human prostate cancer cell line LNCaP and human colorectal cancer cell line HCT116 were used to test the performance of the DEP sorters. In the present work, applied voltage was in the range of 0-20Vp-p, and frequency was from 0 to 10MHz. Comparing to a single side channel DEP cell sorter, the isolation purity was improved from 80 to 96% by a single cascade sorter and the sample throughput was increased from 0.2 to 0.65μL/min by a single staggered side channel sorter. In this article, we report the cell sorter designs, cell separation and enrichment factors. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Yang F.,University of South Carolina | Yang X.,Dorn Research Institute | Jiang H.,GraceFlow Technology | Butler W.M.,South Carolina Oncology Associates | Wang G.,University of South Carolina
Technology in Cancer Research and Treatment | Year: 2013

Separation of cancer cells from other biological materials is significant for circulating tumor cell detection in cancer diagnosis and treatment. However, separation of one type of cancer cell from other types of cancer cells can be difficult, since they share similar morphology and biomarkers. In the present work, we have successfully manipulated and isolated LNCaP prostate cancer cells from HCT116 colorectal cancer cells, by dielectrophoresis (DEP) in a microfluidic platform in a continuous operation. In this cell sorter, the prostate cancer cells were treated as target cells and were deflected to a side channel from a main channel as they experienced a negative DEP force, when an AC electric field at the cross-over frequency of the HCT116 cells was supplied. This motion consequently led to the separation of the prostate cancer cells from the colorectal cancer cells. In this manuscript, we report the flow conditions, DEP spectra of the cancer cells and the isolation of LNCaP cells from HCT116 cells. The separation and enrichment factor have been investigated as well. © Adenine Press (2013).


PubMed | Novartis, Dorn Research Institute, Duke University, University of Colorado at Denver and University of South Carolina
Type: Journal Article | Journal: World journal of urology | Year: 2016

To assess the prostate-specific antigen (PSA) threshold value that optimally predicts future risk of prostate cancer (overall and by race) for a dispersed US population.This was a retrospective analysis of men in the Veterans Affairs (VA) Health Care System database. Men40years with a baseline PSA4.0ng/mL, not receiving 5-alpha reductase inhibitors, and without a prostate cancer diagnosis prior to baseline PSA date were included and followed for 4years. Patients diagnosed with prostate cancer within 6months of baseline were excluded. The optimal PSA threshold value for future 4-year prostate cancer risk was determined by maximizing Youdens index.The eligible population for the final analysis included 41,250 Caucasian (n=24,518; 59.4%) and African American (n=16,732; 40.6%) patients. The 4-year prostate cancer rate was 3.08% overall, and race-specific rates were 3.02 and 3.17% for Caucasian and African American men, respectively. Mean time to prostate cancer diagnosis was 2.01years across all patients. Race-specific PSA thresholds that optimally predicted future prostate cancer were 2.5ng/mL [area under the curve (AUC)=80.3%] in Caucasians and a 1.9ng/mL (AUC=85.4%) in African Americans; across all patients, a 2.4ng/mL threshold was optimal (AUC=82.5%).In the VA population, a relatively low PSA threshold of ~2.5ng/mL was optimal in predicting prostate cancer within 4years overall and for Caucasian men, but an even lower threshold of 1.9ng/mL was applicable for African American men.


Yang X.,Dorn Research Institute | He X.,University of South Carolina | Yang Z.,University of South Carolina | Jabbari E.,University of South Carolina
Biochemistry and Cell Biology | Year: 2012

PER2 is a key mammalian circadian clock protein. It also has a tumor suppressive function. Down regulation of PER2 in the cultured cancer cells accelerates cell proliferation, while overexpression of PER2 inhibits cell growth and induces apoptosis. The Per2 mutant mice have a cancer prone phenotype and an altered DNA damage response. Here we report that PER2 regulates AKT activity. Cells with down-regulated PER2 expression have prolonged high levels of AKT T308 phosphorylation after growth factor stimulation or DNA damage. PER2 down-regulation delays DNA damage induced Chk2 activation and overrides DNA damage induced apoptosis and cell cycle arrest. © 2012 Published by NRC Research Press.


Mercado A.E.,University of South Carolina | Yang X.,Dorn Research Institute | He X.,University of South Carolina | Jabbari E.,University of South Carolina
Journal of Tissue Engineering and Regenerative Medicine | Year: 2014

Bone morphogenetic protein-2 (BMP2) plays a major role in initiating the cascade of osteogenesis. However, high doses of exogenous BMP2 coupled with diffusion away from the intended site cause adverse side-effects. An alternative is to use biodegradable polymeric nanoparticles (NPs) grafted with peptides of the active domains of BMP2. NPs present a multivalent form of the peptide for stronger interaction with cell surface receptors, leading to a stronger activation of osteogenic signalling pathways. The objective of this work was to compare osteogenic activity of the BMP2 peptide (BMP2Pe), corresponding to residues 73-92 of BMP2 protein (BMP2Pr), grafted to biodegradable NPs with that of BMP2 protein (BMP2Pr). BMP2Pe was functionalized with a cysteine residue and grafted to poly(lactide fumarate) and poly(lactide-co-ethylene oxide fumarate) (PLAF/PLEOF) NPs via a thioether link. The calcium content of bone marrow stromal (BMS) cells cultured in osteogenic medium supplemented with BMP2 peptide/protein-grafted NPs (BMP2Pe-gNP and BMP2Pr-gNP) was slightly higher than other BMP2-treated groups, but all osteogenic groups showed similar levels of mineralization after 21days. The expression pattern of master transcription factors Dlx5 and Runx2 indicated that BMP2 protein induced faster osteogenic signalling than the BMP peptide. The expression level of Osteopontin (OP), Osteocalcin (OC) and PECAM-1 in the NP-grafted BMP2 groups was significantly higher than those of ungrafted BMP2Pr and BMP2Pe groups, which may be due to a more effective presentation of the peptide/protein to cell surface receptors, thus leading to a stronger interaction of the peptide/protein with clustered cell surface receptors. © 2012 John Wiley & Sons, Ltd.


Yang X.,University of South Carolina | Yang X.,Dorn Research Institute | Sarvestani S.K.,University of South Carolina | Moeinzadeh S.,University of South Carolina | And 2 more authors.
PLoS ONE | Year: 2013

Introduction: As cancer cells are affected by many factors in their microenvironment, a major challenge is to isolate the effect of a specific factor on cancer stem cells (CSCs) while keeping other factors unchanged. We have developed a synthetic inert 3D polyethylene glycol diacrylate (PEGDA) gel culture system as a unique tool to study the effect of microenvironmental factors on CSCs response. We have reported that CSCs formed in the inert PEGDA gel by encapsulation of breast cancer cells maintain their stemness within a certain range of gel stiffness. The objective was to investigate the effect of CD44 binding peptide (CD44BP) conjugated to the gel on the maintenance of breast CSCs. Methods: 4T1 or MCF7 breast cancer cells were encapsulated in PEGDA gel with CD44BP conjugation. Control groups included dissolved CD44BP and the gel with mutant CD44BP conjugation. Tumorsphere size and density, and expression of CSC markers were determined after 9 days. For in vivo, cell encapsulated gels were inoculated in syngeneic Balb/C mice and tumor formation was determined after 4 weeks. Effect of CD44BP conjugation on breast CSC maintenance was compared with integrin binding RGD peptide (IBP) and fibronectin-derived heparin binding peptide (FHBP). Results: Conjugation of CD44BP to the gel inhibited breast tumorsphere formation in vitro and in vivo. The ability of the encapsulated cells to form tumorspheres in the peptide-conjugated gels correlated with the expression of CSC markers. Tumorsphere formation in vitro was enhanced by FHBP while it was abolished by IBP. Conclusion: CD44BP and IBP conjugated to the gel abolished tumorsphere formation by encapsulated 4T1 cells while FHBP enhanced tumorsphere formation compared to cells in the gel without peptide. The PEGDA hydrogel culture system provides a novel tool to investigate the individual effect of factors in the microenvironment on CSC maintenance without interference of other factors. © 2013 Yang et al.


Jabbari E.,University of South Carolina | Yang X.,University of South Carolina | Yang X.,Dorn Research Institute | Moeinzadeh S.,University of South Carolina | He X.,University of South Carolina
European Journal of Pharmaceutics and Biopharmaceutics | Year: 2013

An exciting approach to tumor delivery is encapsulation of the drug in self-assembled polymer-peptide nanoparticles. The objective of this work was to synthesize a conjugate of low molecular weight polylactide (LMW PLA) and V6K2 peptide and investigate self-assembly, drug release kinetics, cell uptake and toxicity, drug pharmacokinetics, and tumor cell invasion with Doxorubicin (DOX) or paclitaxel (PTX). The results for PLA-V6K2 self-assembled NPs were compared with those of polyethylene glycol stabilized PLA (PLA-EG) NPs. The size of PLA-V6K2 and PLA-EG NPs was 100 ± 20 and 130 ± 50 nm, respectively, with polydispersity index of 1.04 and 1.14. The encapsulation efficiency of DOX in PLA-V6K2 and PLA-EG NPs was 44 ± 9% and 55 ± 5%, respectively, and that of PTX was >90 for both NP types. The release of DOX and PTX from PLA-V6K2 was slower than that of PLA-EG, and the release rate was relatively constant with time. Based on molecular dynamic simulation, the less hydrophobic DOX was distributed in the lactide core as well as the peptide shell, while the hydrophobic PTX was localized mainly to the lactide core. PLA-V6K2 NPs had significantly higher cell uptake by 4T1 mouse breast carcinoma cells compared to PLA-EG NPs, which was attributed to the electrostatic interactions between the peptide and negatively charged moieties on the cell membrane. PLA-V6K2 NPs showed no toxicity to marrow stromal cells. DOX-loaded PLA-V6K2 NPs showed higher toxicity to 4T1 cells and the DNA damage response, and apoptosis was delayed compared to the free DOX. DOX or PTX encapsulated in PLA-V6K2 NPs significantly reduced invasion of 4T1 cells compared to those cells treated with the drug in PLA-EG NPs. Invasion of 4T1 cells treated with DOX in PLA-V6K2 and PLA-EG NPs was 5 ± 1% and 30 ± 5%, respectively, and that of PTX was 11 ± 2% and 40 ± 7%. The AUC of DOX in PLA-V6K2 NPs was 67% and 21% higher than those of free DOX and PLA-EG NPs, respectively. DOX-loaded PLA-V6K2 NPs injected in C3HeB/FeJ mice inoculated with MTCL syngeneic breast cancer cells displayed higher tumor toxicity than PLA-EG NPs and lower host toxicity than the free DOX. Cationic PLA-V6K2 NPs with higher tumor toxicity than the PLA-EG NPs are potentially useful in chemotherapy. © 2012 Elsevier B.V. All rights reserved.


He X.,University of South Carolina | Yang X.,Dorn Research Institute | Jabbari E.,University of South Carolina
Langmuir | Year: 2012

The objective of this work was to investigate the combined effect of grafting the peptide corresponding to amino acid residues 162-168 of osteopontin (OPD peptide) and the peptide corresponding to amino acid residues 73-92 of bone morphogenetic protein-2 (BMP peptide) to an RGD-conjugated inert hydrogel on osteogenic and vasculogenic differentiation of bone marrow stromal (BMS) cells. RGD-conjugated three-dimensional (3D) porous hydrogel scaffolds with well-defined cylindrical pore geometry were produced from sacrificial wax molds fabricated by fused deposition modeling rapid prototyping system. Propargyl acrylate and 4-pentenal were conjugated to the hydrogel for orthogonal grafting of BMP and OPD peptides by click reaction and oxime ligation, respectively. The OPD peptide was grafted by the reaction between aminooxy moiety of aminooxy-mPEG-OPD (mPEG = mini-poly(ethylene glycol)) and the aldehyde moiety in the hydrogel. The BMP peptide was grafted by the reaction between the azide moiety of Az-mPEG-BMP and the propargyl moiety in the hydrogel. The hydrogels seeded with BMS cells were characterized by biochemical, immunocytochemical, and mRNA analyses. Groups included RGD control hydrogel (RGD), RGD and BMP peptides without OPD (RGD+BMP), RGD and BMP peptides with mutant OPD (RGD+BMP+mOPD), and RGD and BMP peptides with OPD (RGD+BMP+OPD) grafted hydrogels. The extent of mineralization of RGD, RGD+BMP, RGD+BMP+mOPD, and RGD+BMP+OPD groups after 28 days was 650 ± 70, 990 ± 30, 850 ± 30, and 1150 ± 40 mg/(mg of DNA), respectively, indicating that the BMP and OPD peptides enhanced osteogenic differentiation of the BMS cells. The BMS cells seeded on RGD+BMP+OPD grafted hydrogels stained positive for vasculogenic markers α-SMA, PECAM-1, and VE-cadherin while the groups without OPD peptide (RGD+BMP and RGD+BMP+mOPD) stained only for α-SMA but not PECAM-1 or VE-cadherin. These results were consistent with the significantly higher PECAM-1 mRNA expression for RGD+BMP+OPD group after 21 and 28 days, compared to the groups without OPD. These findings suggest that the RGD+BMP+OPD peptides provide a favorable microenvironment for concurrent osteogenic and vasculogenic differentiation of progenitor marrow-derived cells. © 2012 American Chemical Society.


Yang X.,University of South Carolina | Yang X.,Dorn Research Institute | Sarvestani S.K.,University of South Carolina | Moeinzadeh S.,University of South Carolina | And 2 more authors.
Tissue Engineering - Part A | Year: 2013

Maintenance of cancer stem cells (CSCs) is regulated by the tumor microenvironment. Synthetic hydrogels provide the flexibility to design three-dimensional (3D) matrices to isolate and study individual factors in the tumor microenvironment. The objective of this work was to investigate the effect of matrix modulus on tumorsphere formation by breast cancer cells and maintenance of CSCs in an inert microenvironment without the interference of other factors. In that regard, 4T1 mouse breast cancer cells were encapsulated in inert polyethylene glycol diacrylate hydrogels and the effect of matrix modulus on tumorsphere formation and expression of CSC markers was investigated. The gel modulus had a strong effect on tumorsphere formation and the effect was bimodal. Tumorsphere formation and expression of CSC markers peaked after 8 days of culture. At day 8, as the matrix modulus was increased from 2.5 kPa to 5.3, 26.1, and 47.1 kPa, the average tumorsphere size changed from 37±6 μm to 57±6, 20±4, and 12±2 μm, respectively; cell number density in the gel changed from 0.8±0.1×105 cells/mL to 1.7±0.2×105, 0.4±0.1×10 5, and 0.2±0.1×105 cells/mL after initial encapsulation of 0.14×105 cells/mL; and the expression of CD44 breast CSC marker changed from 17±4-fold to 38±9-, 3±1-, and 2±1-fold increase compared with the initial level. Similar results were obtained with MCF7 human breast carcinoma cells. Mouse 4T1 and human MCF7 cells encapsulated in the gel with 5.3 kPa modulus formed the largest tumorspheres and highest density of tumorspheres, and had highest expression of breast CSC markers CD44 and ABCG2. The inert polyethylene glycol hydrogel can be used as a model-engineered 3D matrix to study the role of individual factors in the tumor microenvironment on tumorigenesis and maintenance of CSCs without the interference of other factors. © Copyright 2013, Mary Ann Liebert, Inc. 2013.

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