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1.
ACS Appl Mater Interfaces ; 16(14): 17313-17322, 2024 Apr 10.
Article in English | MEDLINE | ID: mdl-38534029

ABSTRACT

Glucose oxidase (Gox)-mediated starvation therapy offers a prospective advantage for malignancy treatment by interrupting the glucose supply to neoplastic cells. However, the negative charge of the Gox surface hinders its enrichment in tumor tissues. Furthermore, Gox-mediated starvation therapy infiltrates large amounts of hydrogen peroxide (H2O2) to surround normal tissues and exacerbate intracellular hypoxia. In this study, a cascade-catalyzed nanogel (A-NE) was developed to boost the antitumor effects of starvation therapy by glucose consumption and cascade reactive release of nitric oxide (NO) to relieve hypoxia. First, the surface cross-linking structure of A-NE can serve as a bioimmobilization for Gox, ensuring Gox stability while improving the encapsulation efficiency. Then, Gox-mediated starvation therapy efficiently inhibited the proliferation of tumor cells while generating large amounts of H2O2. In addition, covalent l-arginine (l-Arg) in A-NE consumed H2O2 derived from glucose decomposition to generate NO, which augmented starvation therapy on metastatic tumors by alleviating tumor hypoxia. Eventually, both in vivo and in vitro studies indicated that nanogels remarkably inhibited in situ tumor growth and hindered metastatic tumor recurrence, offering an alternative possibility for clinical intervention.


Subject(s)
Neoplasms , Nitric Oxide , Polyethylene Glycols , Polyethyleneimine , Humans , Nanogels , Hydrogen Peroxide/chemistry , Prospective Studies , Neoplasms/pathology , Glucose Oxidase/chemistry , Catalysis , Glucose , Cell Line, Tumor
2.
ACS Appl Mater Interfaces ; 15(28): 33309-33321, 2023 Jul 19.
Article in English | MEDLINE | ID: mdl-37408134

ABSTRACT

Chemotherapy predominates in clinical treatment of prostate cancer (PCa), while irreversible resistance to chemotherapeutics and severe side effects hinder the therapeutic efficacy, especially in castration-resistant PCa (CRPC). Herein, a bombesin (BBN)-decorated two-in-one prodrug (T-NO/E2-PMs) incorporating a polymeric nitric oxide (NO) donor and acetal-linked 17ß-estradiol (E2) in one backbone is developed, aiming to inhibit androgen receptor (AR) expression, reprogram the tumor microenvironment of CRPC, and enhance estradiol-mediated hypoxic CRPC therapy. Following efficient internalization mediated by BBN, T-NO/E2-PMs releases estradiol and NO in response to the unique intracellular environments. Both in vitro and in vivo studies demonstrate that the T-NO/E2-PMs nano-prodrug along with NO release potently downregulates AR levels to reverse CRPC and further enhances the chemo-sensitization of estradiol to PCa PC-3 cell apoptosis and the inhibition of metastasis. Collectively, this two-in-one nano-prodrug strategy offers a promising platform for construction of advanced nanomedicine to boost the therapeutic efficacy.


Subject(s)
Prodrugs , Prostatic Neoplasms, Castration-Resistant , Male , Humans , Prostatic Neoplasms, Castration-Resistant/drug therapy , Prostatic Neoplasms, Castration-Resistant/metabolism , Prostatic Neoplasms, Castration-Resistant/pathology , Prodrugs/pharmacology , Prodrugs/therapeutic use , Nitric Oxide Donors/pharmacology , Nitric Oxide Donors/therapeutic use , Prostate/pathology , Estradiol , Nitric Oxide/therapeutic use , Cell Line, Tumor , Tumor Microenvironment
3.
PLoS One ; 18(6): e0287344, 2023.
Article in English | MEDLINE | ID: mdl-37319289

ABSTRACT

Magnetic resonance imaging (MRI) is a powerful noninvasive diagnostic tool with superior soft tissue contrast. However, access to MRI is limited since current systems depend on homogeneous, high field strength main magnets (B0-fields), with strong switchable gradients which are expensive to install and maintain. In this work we propose a new approach to MRI where imaging is performed in an inhomogeneous field using radiofrequency spatial encoding, thereby eliminating the need for uniform B0-fields and conventional cylindrical gradient coils. The proposed technology uses an innovative data acquisition and reconstruction approach by integrating developments in field cycling, parallel imaging and non-Fourier based algebraic reconstruction. The scanner uses field cycling to image in an inhomogeneous B0-field; in this way magnetization is maximized during the high field polarization phase, and B0 inhomogeneity effects are minimized by using a low field during image acquisition. In addition to presenting the concept, this work provides experimental verification of a long-lived spin echo signal, spatially varying resolution, as well as both simulated and experimental 2D images. Our initial design creates an open MR system that can be installed in a patient examination table for body imaging (e.g., breast or liver) or built into a wall for weighted-spine imaging. The proposed system introduces a new class of inexpensive, open, silent MRIs that could be housed in doctor's offices much like ultrasound is today, making MRI more widely accessible.


Subject(s)
Magnetic Resonance Imaging , Magnets , Humans , Magnetic Resonance Imaging/methods , Magnetic Fields
4.
Sci Rep ; 11(1): 440, 2021 Jan 11.
Article in English | MEDLINE | ID: mdl-33432009

ABSTRACT

A gold-silver-lead-zinc polymetallic ore was selected in Huaniushan, Gansu Province as the study area. Hyperspectral aerial images as the primary information source, ground spectrum tests, and sampling analysis were used as auxiliary techniques. They were combined with large-scale mineral and geological maps and other high-resolution satellite remote sensing images. Hyperspectral remote sensing classification identification and quantitative analysis methods were used to study the main mineral resources and rock mass occurrence. Finally, deposit distribution information was extracted and validated. The results showed that the effective classification methods by hyperspectral images were spectral angle mapping, minimum noise fraction transform, and mixed tuned matched filtering. Based on the ground survey, combined with sampling analysis, the accuracy of classification was 80%. The recognition rate of the main ore body-the iron-manganese cap lead-zinc oxide ore-was as high as 81%. This research showed that hyperspectral remote sensing in this mining area has excellent demonstration effects and is worth completing and supplementing original mineral and geological maps. The targets are important areas for detailed follow-up on mineral resource exploration.

5.
J Zhejiang Univ Sci B ; 16(11): 914-23, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26537209

ABSTRACT

OBJECTIVE: In our previous work, we prepared a type of chitosan hydrogel with excellent biocompatibility. In this study, tissue-engineered cartilage constructed with this chitosan hydrogel and costal chondrocytes was used to repair the articular cartilage defects. METHODS: Chitosan hydrogels were prepared with a crosslinker formed by combining 1,6-diisocyanatohexane and polyethylene glycol. Chitosan hydrogel scaffold was seeded with rabbit chondrocytes that had been cultured for one week in vitro to form the preliminary tissue-engineered cartilage. This preliminary tissue-engineered cartilage was then transplanted into the defective rabbit articular cartilage. There were three treatment groups: the experimental group received preliminary tissue-engineered cartilage; the blank group received pure chitosan hydrogels; and, the control group had received no implantation. The knee joints were harvested at predetermined time. The repaired cartilage was analyzed through gross morphology, histologically and immunohistochemically. The repairs were scored according to the international cartilage repair society (ICRS) standard. RESULTS: The gross morphology results suggested that the defects were repaired completely in the experimental group after twelve weeks. The regenerated tissue connected closely with subchondral bone and the boundary with normal tissue was fuzzy. The cartilage lacuna in the regenerated tissue was similar to normal cartilage lacuna. The results of ICRS gross and histological grading showed that there were significant differences among the three groups (P<0.05). CONCLUSIONS: Chondrocytes implanted in the scaffold can adhere, proliferate, and secrete extracellular matrix. The novel tissue-engineered cartilage constructed in our research can completely repair the structure of damaged articular cartilage.


Subject(s)
Cartilage, Articular/surgery , Chitosan/therapeutic use , Chondrocytes/transplantation , Tissue Engineering/methods , Animals , Cartilage, Articular/pathology , Female , Hydrogels , Immunohistochemistry , Male , Rabbits
6.
J Mater Sci Mater Med ; 25(8): 1903-13, 2014 Aug.
Article in English | MEDLINE | ID: mdl-24805882

ABSTRACT

Traditional chitosan hydrogels were prepared by chemical or physical crosslinker, and both of the two kinds of hydrogels have their merits and demerits. In this study, researchers attempted to prepare one kind of chitosan hydrogel by slightly crosslinker, which could combine the advantages of the two kinds of hydrogels. In this experiment, the crosslinker was formed by a reaction between the isocyanate group of 1,6-diisocyanatohexan and the hydroxyl group of polyethylene glycol-400 (PEG-400), then the crosslinker reacted with the amidine and the hydroxyl group of ethylene glycol chitosan to form the network structure. Physical properties of the hydrogel were tested by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and biodegradation. Biocompatibility was assessed by cell implantation in vitro and the scaffold was used as a cartilage tissue engineering scaffold to repair a defect in rabbit knee joints in vivo. FTIR results show the formation of a covalent bond during thickening of the ethylene glycol chitosan. SEM and degradation experiments showed that the ethylene glycol chitosan hydrogel is a 3-D, porous, and degradable scaffold. The hydrogel contained 2% ethylene glycol chitosan and 10 µl crosslinker was selected for the biocompatibility experiment in vitro and in vivo. After chondrocytes were cultured in the ethylene glycol chitosan hydrogel scaffold for 1 week cells exhibited clustered growth and had generated extracellular matrix on the scaffold in vitro. The results in vivo showed that hydrogel-chondrocytes promoted the repair of defect in rabbits. Based on these results, it could be concluded that ethylene glycol chitosan hydrogel is a scaffold with excellent physicochemical properties and it is a promising tissue engineering scaffold.


Subject(s)
Chitosan/chemistry , Hydrogels , Isocyanates/chemistry , Polyethylene Glycols/chemistry , Tissue Engineering , Tissue Scaffolds , Animals , Cells, Cultured , Chondrocytes/metabolism , In Vitro Techniques , Microscopy, Electron, Scanning , Rabbits , Spectroscopy, Fourier Transform Infrared
7.
Med Phys ; 40(6): 063102, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23718610

ABSTRACT

PURPOSE: Prostate cancer ranks as one of the most common malignancies and currently represents the second leading cancer-specific cause of death in men. The current use of single modality transrectal ultrasound (TRUS) for biopsy guidance has a limited sensitivity and specificity for accurately identifying cancerous lesions within the prostate. This study introduces a novel prostate cancer imaging method that combines TRUS with electrical impedance tomography (EIT) and reports on initial clinical findings based on in vivo measurements. METHODS: The ultrasound system provides anatomic information, which guides EIT image reconstruction. EIT reconstructions are correlated with semiquantitative pathological findings. Thin plate spline warping transformations are employed to overlay electrical impedance images and pathological maps describing the spatial distribution of prostate cancer, with the latter used as reference for data analysis. Clinical data were recorded from a total of 50 men prior to them undergoing radical prostatectomy for prostate cancer treatment. Student's t-tests were employed to statistically examine the electrical property difference between cancerous tissue and benign tissue as defined through histological assessment of the excised gland. RESULTS: Example EIT reconstructions are presented along with a statistical analysis comparing EIT and pathology. An average transformation error of 1.67% is found when 381 spatially coregistered pathological images are compared with their target EIT reconstructed counterparts. At EIT signal frequencies of 0.4, 3.2, and 25.6 kHz, paired-testing demonstrated that the conductivity of cancerous regions is significantly greater than that of benign regions ( p < 0.0304). CONCLUSIONS: These preliminary clinical findings suggest the potential benefits electrical impedance measurements might have for prostate cancer detection.


Subject(s)
Endoscopic Ultrasound-Guided Fine Needle Aspiration/methods , Image Interpretation, Computer-Assisted/methods , Plethysmography, Impedance/methods , Prostatic Neoplasms/diagnosis , Subtraction Technique , Tomography/methods , Humans , Male , Reproducibility of Results , Sensitivity and Specificity
8.
Physiol Meas ; 34(6): 623-44, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23719063

ABSTRACT

Imaging the electrical properties of human tissue may aid in cancer diagnoses or monitoring organ function. Traditionally, the electrical properties are revealed with electrical impedance tomography, where currents are injected into human tissue and voltages are measured on the surface. This paper focuses on a method of measuring the electrical properties using a magnetic resonance (MR) scanner without current injection. In magnetic resonance driven electrical impedance tomography (MRDEIT), the MR phenomenon is used to induce currents in the body and the complex permittivity map is inversely computed from the difference between the modeled electric field and the actual surface electrode measurements. Computer simulations indicate that with noise level under 20%, the contrast is visually discernible in the reconstruction image. A phantom experiment is demonstrated and this supports results from computer simulation studies. The noise level in electrode measurements is evaluated to be approximately 7.8% from repeated experiments, confirming the potential to reconstruct conductivity contrast using MRDEIT. With further improvements in hardware and image reconstruction, MRDEIT may provide an additional contrast mechanism reflecting the electrical properties of human tissue, which may ultimately be used to diagnose a cancer or assist in electroencephalography.


Subject(s)
Magnetic Resonance Spectroscopy , Phantoms, Imaging , Tomography/methods , Artifacts , Computer Simulation , Copper , Electric Impedance , Electrodes , Feasibility Studies , Humans , Image Processing, Computer-Assisted
9.
J Tissue Eng ; 3(1): 2041731412454420, 2012.
Article in English | MEDLINE | ID: mdl-22919457

ABSTRACT

Interbody fusion is an established procedure to preserve disk height and anterior fusion, but fusion with autografts, allografts, and metallic cages has its endogenous shortcomings. The objective of this study is to investigate whether a biphasic scaffold model, the native demineralized bone matrix cylinder in conjunction with degradable biomaterial poly(polycaprolactone triol malate), can be employed as a biological graft for interbody fusion. The poly(polycaprolactone triol malate) was synthesized by polycondensing malic acid and polycaprolactone and then the concentric sheet of poly(polycaprolactone triol malate) was fabricated into the demineralized bone matrix cylinder derived from rabbit femurs. Rabbit chondrocytes were loaded onto the three-dimensional constructs with 1-day in vitro culture and implanted into the subcutaneous dorsal pocket of nude mice. The chondrocytes/scaffold constructs are approximately two folds bigger than the scaffold-alone constructs after 12 weeks of implantation. X-ray and micro-computed tomography imaging showed endochondral bone formation in the chondrocytes/scaffold constructs as early as 4 weeks and showed that the bone intensity increased over time. Histological staining confirmed the above observation. By week 8, lamellar bone tissues were formed inside the demineralized bone matrix cylinder. In addition, the compression biomechanical test showed that the chondrocytes/scaffold constructs produced a significant higher compressive strength compared to the scaffold group. These results demonstrated that the inner-phase poly(polycaprolactone triol malate) degraded over time and was replaced by new bone in an in vivo environment.

10.
Article in English | MEDLINE | ID: mdl-23367350

ABSTRACT

Previous studies have shown that prostate cancer may be detected by a combined transrectal ultrasound and electrical impedance tomography imaging system. However, the sensitivity of the imaging system is limited due to very little current established in the far field distant from the probe surface. Consequently, biopsy needles are introduced to the imaging system to provide current paths in the distal regions. This study demonstrates that image sensitivity can be improved by incorporating the needle electrodes. A phantom experiment is presented to show that contrast to the background is enhanced by 17.4% when imaging with needle electrodes. Simulated reconstructions and some preliminary clinical data also suggest the sensitivity improvement. In summary, TREIT with needle electrodes in the tissue may have great potential in future clinical prostate cancer detection.


Subject(s)
Biopsy, Needle , Electric Impedance , Electrodes , Needles , Rectum , Humans , Male , Phantoms, Imaging
11.
IEEE Trans Biomed Eng ; 58(8)2011 Aug.
Article in English | MEDLINE | ID: mdl-21402505

ABSTRACT

The goal of the paper is to propose a fast and reliable method of simultaneous estimation of conductivity and electrode contact impedances for a homogeneous 2D disk. Magic Toeplitz matrix as the Neumann-to-Dirichlet map with finite width electrodes plays the central role in our linear model, called the gapZ model. This model enables testing of various hypotheses using the F-test, such as the uniformity of electrode impedances and their statistical significance. The gapZ model is compared with the finite element approximation, and illustrated and validated with a phantom tank experiment filled with saline. Further this model was illustrated with the patient breast EIT data to identify bad contact electrodes.


Subject(s)
Algorithms , Breast/physiology , Dielectric Spectroscopy/instrumentation , Electrodes , Equipment Failure Analysis/methods , Models, Biological , Computer Simulation , Equipment Design , Humans
12.
J Orthop Res ; 27(6): 814-9, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19030173

ABSTRACT

Many of the therapeutic interventions for intervertebral disc degeneration attempt to repopulate the nucleus pulposus (NP) tissue; however, NP cells are heterogeneous and not well characterized. To address this, we have investigated the morphology, extracellular gene and protein expression, and apoptosis changes in NP explants cultured in vitro with or without chondrogenic reagents for different periods. We also compared the susceptibility of the explants to different treatments by comparing: treatment of NP explants with GDF5 protein, transfection of NP explants with GDF5 plasmid, and infection of NP explants with GDF5 adenovirus vector. We found that expression levels of two of the major extracellular proteins found in NP tissue, that is, collagen II and aggrecan, could be maintained in an NP explant culture model with a chondrogenic medium up to 7 days, and were significantly higher than that of fresh NP tissue after 14 days of culture in vitro, whether or not chondrogenic medium was used. In addition, the NP explant responded to treatment with growth factor, and could be infected by virus and transfected by plasmid for further evaluation of growth factor gene therapy. NP explant culture could therefore provide an easy in vitro culture model to characterize NP cells and evaluate potential therapeutic reagents.


Subject(s)
Genetic Therapy/methods , Growth Differentiation Factor 5/genetics , Intervertebral Disc Displacement/genetics , Intervertebral Disc Displacement/therapy , Intervertebral Disc/physiology , Organ Culture Techniques/methods , Adenoviridae/genetics , Aggrecans/genetics , Animals , Apoptosis/drug effects , Apoptosis/physiology , Collagen Type II/genetics , Extracellular Matrix/physiology , Growth Differentiation Factor 5/pharmacology , In Situ Nick-End Labeling , Intervertebral Disc/cytology , Intervertebral Disc Displacement/pathology , Plasmids , Rabbits , Recombinant Proteins/genetics , Recombinant Proteins/pharmacology , Transfection
13.
Growth Factors ; 26(3): 132-42, 2008 Jun.
Article in English | MEDLINE | ID: mdl-18569021

ABSTRACT

The repair of articular cartilage injuries is impeded by the avascular and non-innervated nature of cartilage. Transplantation of autologous chondrocytes has a limited ability to augment the repair process due to the highly differentiated state of chondrocytes and the risks of donor-site morbidity. Mesenchymal stem cells can undergo chondrogenesis in the presence of growth factors for cartilage defect repair. Growth and differentiation factor-5 (GDF5) plays an important role in chondrogenesis. In this study, we examined the effects of GDF5 on chondrogenesis of adipose-derived stem cells (ADSCs) and evaluate the chondrogenic potentials of GDF5 genetically engineered ADSCs using an in vitro pellet culture model. Rat ADSCs were grown as pellet cultures and treated with chondrogenic media (CM). Induction of GDF5 by an adenovirus (Ad-GDF5) was compared with exogenous supplementation of GDF5 (100 ng/ml) and transforming growth factor-beta (TGF-beta1; 10 ng/ml). The ADSCs underwent chondrogenic differentiation in response to GDF5 exposure as demonstrated by production of proteoglycan, and up-regulation of collagen II and aggrecan at the protein and mRNA level. The chondrogenic potential of a one-time infection with Ad-GDF5 was weaker than exogenous GDF5, but equal to that of TGF-beta1. Stimulation with growth factors or CM alone induced transient expression of the mRNA for collagen X, indicating a need for optimization of the CM. Our findings indicate that GDF5 is a potent inducer of chondrogenesis in ADSCs, and that ADSCs genetically engineered to express prochondrogenic growth factors, such as GDF5, may be a promising therapeutic cell source for cartilage tissue engineering.


Subject(s)
Adenoviridae/genetics , Adipose Tissue/cytology , Bone Morphogenetic Proteins/metabolism , Gene Expression Regulation , Stem Cells/cytology , Tissue Engineering/methods , Animals , Cartilage/metabolism , Cell Culture Techniques/methods , Cell Differentiation , Chondrogenesis , Genetic Therapy/methods , Growth Differentiation Factor 5 , RNA, Messenger/metabolism , Rats , Transforming Growth Factor beta1/metabolism
14.
Spine J ; 8(2): 287-95, 2008.
Article in English | MEDLINE | ID: mdl-17974491

ABSTRACT

BACKGROUND CONTEXT: Growth and differentiation factor-5 (GDF-5)-deficient mice showed abnormalities in intervertebral disc (IVD) structure and extracellular matrix. Adenovirus-mediated GDF-5 delivery can promote the growth of rabbit disc cells. PURPOSE: The aim of the present study was to investigate the effect of recombinant GDF-5 protein and GDF-5 complementary DNA (cDNA) on the metabolism of IVD cells. STUDY DESIGN: The effects of recombinant GDF-5 protein and GDF-5 cDNA on mouse IVD cells will be evaluated in vitro. METHODS: Mouse disc cells in vitro were treated with recombinant GDF-5 protein. Mouse GDF-5 cDNA was cloned into an expression vector and was used to transfect mouse disc cells in vitro. Therapy with GDF-5 protein and cDNA was assessed by measuring cell proliferation, proteoglycan production, and extracellular matrix gene expression. RESULTS: Biochemical assays revealed an elevated sulfated glycosaminoglycan (GAG)/DNA ratio in mouse IVD cells that were cultured in the presence of various concentrations of mouse GDF-5(mGDF-5) protein. Real-time reverse transcription-polymerase chain reaction (RT-PCR) demonstrated that treating the cells with GDF-5 protein increased the expression of the collagen Type II and aggrecan genes in a dose-dependent manner but decreased matrix metalloproteinase (MMP)-3 gene expression. Immunohistochemistry showed an increase in the aggregation of mouse IVD cells that were treated with mGDF-5 in culture compared with the control group. The mouse GDF-5 gene was successfully cloned into an expression plasmid vector, and GDF-5 protein production was confirmed by Western blot analysis. Type II collagen and aggrecan gene expression by the cells increased significantly in the cells that were transfected by nucleofection with the GDF-5 plasmid compared with cells that were transfected with a control plasmid. CONCLUSIONS: This is the first report of the cloning of the mouse GDF-5 gene and use of the nucleofection method to transfer DNA into IVD cells. The data suggest that both recombinant protein and the cDNA forms of GDF-5 can increase the expression of genes for extracellular matrix proteins in mouse IVD cells. Future attempts at gene therapy to treat degenerative disc disease with a novel ex vivo gene transfer technique are needed to develop a therapy that would alleviate the condition of patients with clinically relevant axial spine pain.


Subject(s)
Bone Morphogenetic Proteins/genetics , Chondrocytes/metabolism , Genetic Therapy/methods , Intervertebral Disc/cytology , Aggrecans/biosynthesis , Aggrecans/genetics , Animals , Blotting, Western , Bone Morphogenetic Proteins/metabolism , Cell Aggregation , Cloning, Molecular , Collagen Type II/biosynthesis , Collagen Type II/genetics , DNA, Complementary , Gene Expression , Growth Differentiation Factor 5 , Immunohistochemistry , Intervertebral Disc/metabolism , Mice , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Transfection
15.
Biomaterials ; 29(6): 643-52, 2008 Feb.
Article in English | MEDLINE | ID: mdl-17997480

ABSTRACT

Intervertebral disc (IVD) degeneration is the major cause of lower back pain, while the currently available treatments are symptomatic rather than curative. Tissue engineering is a powerful therapeutic strategy that can restore the normal biomechanical motion of the human spine. The ability of a biphasic elastic scaffold to structurally and elastically simulate the annulus fibrosus (AF) tissue of the IVD was explored. The outer phase of the scaffold was a ring-shaped demineralized bone matrix gelatin (BMG) extracted from cortical bone, which mimicks the type I collagen structure and ligamentous properties of outer AF. The inner phase of the scaffold was a bio-biomaterial poly(polycaprolactone triol malate) (PPCLM) orientated in concentric sheets and seeded with chondrocytes to recapitulate the inner layer of the AF, which is rich in type II collagen and proteoglycan. The mechanical properties and degradation of PPCLM could be adjusted by controlling the post-polymerization time of the pre-polymer. PPCLM also demonstrated good biocompatibility in a foreign body response in vivo assay. Incorporation of BMG into the scaffold enhanced the compressive strength compared with PPCLM alone. In addition, the tensile stress of the BMG/PPCLM scaffold was 50-fold greater than that of PPCLM alone, and close to that of normal rabbit AF. Finally, the biphasic scaffold supported the growth of rabbit chondrocytes, as confirmed by Safranin-O and type II collagen immunostaining. The excellent mechanical properties and biocompatibility of the BMG/PPCLM scaffold make it a promising candidate for AF repair.


Subject(s)
Intervertebral Disc/physiology , Regeneration , Tissue Engineering , Animals , Rabbits , Spectroscopy, Fourier Transform Infrared
16.
Article in English | MEDLINE | ID: mdl-19162875

ABSTRACT

Electrical impedance tomography (EIT) is a promising technology enabling the detection or observation of many biological processes. This is typically accomplished by applying currents at known locations on an outer surface (in this case skin) and measuring voltages at other locations. This information is then used to determine electrical properties of tissue found between the electrodes by solving the associated Laplace equation. Such problems depend upon knowing the exact boundary conditions (BC). Unfortunately BCs are not always easily determined and approximations are accepted out of necessity due to problem complexity or time constraints. The EIT group at Dartmouth College has developed two new patient interfaces for breast cancer detection and monitoring both of which speed acquisition time and allow for precision BC information in natural and arbitrary geometries. Preliminary experimental results are presented.


Subject(s)
Breast Neoplasms/diagnosis , Electrodes , Imaging, Three-Dimensional/instrumentation , Plethysmography, Impedance/instrumentation , Tomography/instrumentation , Equipment Design , Equipment Failure Analysis , Imaging, Three-Dimensional/methods , Plethysmography, Impedance/methods , Reproducibility of Results , Sensitivity and Specificity , Tomography/methods
17.
Macromol Biosci ; 7(11): 1217-24, 2007 Nov 12.
Article in English | MEDLINE | ID: mdl-17683110

ABSTRACT

A novel elastic scaffold that simulates the deformability of annulus fibrosus (AF) and has good biocompatibility was developed. The scaffold was formed of a malic acid-based polyester poly(1,8-octanediol malate) (POM), which was synthesized by direct polycondensation. The tensile strength of POM gradually increased with the extension of the polymerization time, while the degradation rate decreased. Rat AF cells proliferated on the POM films and maintained their phenotype. The 3D scaffold also supported the growth of the AF cells, as confirmed by Safranin-O and type II collagen staining. POM also demonstrated a good biocompatibility in an in vivo foreign body response assay, an important prerequisite for tissue engineering applications. This study suggests that elastic POM scaffold may be an ideal candidate for AF tissue engineering.


Subject(s)
Intervertebral Disc/cytology , Intervertebral Disc/surgery , Malates/chemistry , Polymers/chemistry , Regeneration , Aggrecans/genetics , Aggrecans/metabolism , Animals , Biocompatible Materials/chemistry , Biodegradation, Environmental , Cells, Cultured , Collagen Type II/genetics , Collagen Type II/metabolism , Coloring Agents/metabolism , Compressive Strength , Elasticity , Gene Expression , Intervertebral Disc/ultrastructure , Lumbar Vertebrae/anatomy & histology , Nuclear Magnetic Resonance, Biomolecular , Phenazines/metabolism , Polyesters/chemistry , Proteoglycans/biosynthesis , Proteoglycans/metabolism , Rats , Rats, Inbred F344 , Tensile Strength , Time Factors
18.
Biomaterials ; 27(13): 2699-704, 2006 May.
Article in English | MEDLINE | ID: mdl-16412503

ABSTRACT

Hydrophobicity of poly(L-lactide) scaffolds is a main drawback in obtaining a sufficient mass of seeded cells for satisfying the requirements of tissue engineering. Plasma treatment is a useful technique to enhance the hydrophilicity of the scaffolds. However, the effect of this technique on the modifying depth and degradation of the scaffolds should be considered. In this paper, the influence of NH3 plasma treatment on the modifying depth and degradation of scaffolds were investigated. The results showed that the modifying depth of the scaffolds increased with treating time and the plasma power ranging from 20 to 80 W influenced the depth slightly. However, the degradation of the scaffolds increased with increasing treatment time and plasma power. The results also showed that the plasma intruded the scaffolds gradually from top to bottom. For a 4 mm thick scaffold, the optimized treatment condition was 20 W of power in a 30 Pa ammonia atmosphere for 30 min of treating time. Under this condition, the integrity of scaffold could be relatively well kept. NH3 plasma treatment enabled the penetration of cells into scaffolds and facilitated the proliferation of cells in them.


Subject(s)
Ammonia/chemistry , Biocompatible Materials/chemistry , Cell Adhesion/physiology , Cell Culture Techniques/methods , Cell Survival/physiology , Polyesters/chemistry , Tissue Engineering/methods , 3T3 Cells , Absorbable Implants , Animals , Biocompatible Materials/analysis , Cell Proliferation , Gases , Hot Temperature , Hydrophobic and Hydrophilic Interactions , Materials Testing , Mice , Porosity , Surface Properties
19.
Biomaterials ; 27(2): 216-25, 2006 Jan.
Article in English | MEDLINE | ID: mdl-16054684

ABSTRACT

Porcine-derived xenogeneic bone (PDXB) was derived from cancellous bone of adult porcine. Its morphology and structure were characterized by SEM, FTIR and XRD. A series of composite films consisting of PDXB and poly(glycolide-co-lactide-co-caprolactone) (PGLC) polymer were prepared. Because of the introduction of PGLC polymer, the PDXB/PGLC composites especially PDXB/PGLC(30/70) and PDXB/PGLC(50/50) showed good processability and mechanical properties. In addition, the hydrophilicity of the composites was enhanced as well since the PDXB component was hydrophilic. Osteoblast-like cells (OCT-1) were used as an in-vitro model to assess the affinity of the PDXB/PGLC composites. It was found that compared with the pure PGLC film, PDXB/PGLC(30/70) and PDXB/PGLC(50/50) composite films promoted cell attachment, proliferation and ALP (alkaline phosphatase) activity obviously. In addition, the cells preferred growing on the areas of exposed PDXB. It was considered that the hydrophilicity, osteoconductivity and appropriate surface roughness (Sa=3.30, 4.00 microm) induced by PDXB facilitate cell growth. However, the introduction of too much PDXB, such as PDXB/PGLC(70/30) film, would obtain an adverse effect on the cell growth since the value of Sa was up to 7.33 microm. It indicated that only the composites with appropriate surface topography could favor cell growth. Surface topography probably has a more important effect on cell growth process than surface chemistry.


Subject(s)
Biocompatible Materials/chemistry , Osteoblasts/metabolism , Polyesters/chemistry , Polyglycolic Acid/chemistry , Transplantation, Heterologous , Animals , Bone Substitutes/chemistry , Bone and Bones/ultrastructure , Cell Line , Cell Shape , Materials Testing , Osteoblasts/cytology , Particle Size , Rats , Surface Properties , Swine , Tensile Strength , Tissue Engineering , Water/chemistry
20.
Biomaterials ; 26(21): 4453-9, 2005 Jul.
Article in English | MEDLINE | ID: mdl-15701374

ABSTRACT

The impact of the surface topography of polylactone-type polymer on cell adhesion was to be concerned because the micro-scale texture of a surface can provide a significant effect on the adhesion behavior of cells on the surface. Especially for the application of tissue engineering scaffold, the pore size could have an influence on cell in-growth and subsequent proliferation. Micro-fabrication technology was used to generate specific topography to investigate the relationship between the cells and surface. In this study the pits-patterned surfaces of polystyrene (PS) film with diameters 2.2 and 0.45 microm were prepared by phase-separation, and the corresponding scale islands-patterned PLLA surface was prepared by a molding technique using the pits-patterned PS as a template. The adhesion and proliferation behavior of OCT-1 osteoblast-like cells morphology on the pits- and islands-patterned surface were characterized by SEM observation, cell attachment efficiency measurement and MTT assay. The results showed that the cell adhesion could be enhanced on PLLA and PS surface with nano-scale and micro-scale roughness compared to the smooth surfaces of the PLLA and PS. The OCT-1 osteoblast-like cells could grow along the surface with two different size islands of PLLA and grow inside the micro-scale pits of the PS. However, the proliferation of cells on the micro- and nano-scale patterned surface has not been enhanced compared with the controlled smooth surface.


Subject(s)
Biocompatible Materials/chemistry , Cell Adhesion/physiology , Nanostructures/chemistry , Osteoblasts/cytology , Osteoblasts/physiology , Polyesters/chemistry , Tissue Engineering/methods , Animals , Cell Culture Techniques/methods , Cell Line , Cell Proliferation , Cell Size , Humans , Materials Testing , Nanostructures/ultrastructure , Surface Properties
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