Jessie K. Kanwal, B.S. [1], David Wu, B.S. [1], Kirsti A. Campbell, B.S. [1]
[1] Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
[2] Department of Biology, University of Virginia, Charlottesville, Virginia
The Undergraduate Research Network (URN) was formed in 2001 to foster an undergraduate research community at the University of Virginia(UVA).
Now in its 10th year of existence, URN continues to promote undergraduate research. In particular, URN hopes to:
1. Encourage students to initiate research projects.
2. Present information about current research opportunities.
3. Increase the visibility of undergraduate research at UVA.
4. Offer guidance and mentorship to students interested in research.
5. Publicize funding opportunities and research-related events.
6. Increase undergraduate access to UVA's resources.
7. Provide a forum for students to showcase the results of their research and reflect upon their experience.
Jessleen K. Kanwal, B.S. [1], Peter M. Pollak, M.D. [2], Srijoy Mahapatra, M.D. [2], George T. Gillies, Ph.D [3]
[1] Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
[2] Division of Cardiovascular Medicine, University of Virginia, Charlottesville, Virginia
[3] Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia
We have designed, built and tested a novel needle for percutaneously accessing the pericardial space. The problem with accessing pericardial space is that the pericardium is against the heart. Our novel device incorporates a single spiral tine at the distal tip of a 10 Gauge needle, which engages the parietal pericardium tangentially to the surface of the heart. One can then pull the pericardium away, thus minimizing the risk of ventricular perforation associated with oblique axial approaches. Using linear low-density polyethylene film as a surrogate pericardium, we have demonstrated reliable pericardial engagement with successful first-time engagement rates of up to 72% (n = 25 attempts) at approach angles ranging from 0º (normal incidence) to 30º. The spiral needle is able in principle to retract the pericardium after engaging it, and thus tent it away from the epicardial surface. The needle’s design is intended to maximize the reliability of pericardial access while minimizing the risk of perforation injuries to nearby structures.
Tojan B. Rahhal [2]
[1] Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, North Carolina
[2] Department of Biomedical Engineering, North Carolina State University, Raleigh, North Carolina
Sp proteins are responsible for the regulation of a wide variety of genes, many of which play important roles in animal development. Sp3 encodes three isoforms (Sp3, M1, and M2) that are synthesized from a single mRNA. Each isoform carries the Sp3 DNA-binding domain as well as lysine 551 (K551), the major site of a post-translational modification termed sumoylation. Sumoylation of Sp3 isoforms at K551 has been shown to control Sp3 function in vitro. To determine if this is also the case in vivo, transgenic animals were created that over-express wild-type or mutated Sp3 proteins lacking K551. The focus of my work has been to determine the functional requirement for Sp3 sumoylation on stem cells of the skin. Interestingly, mice carrying a sumoylation-deficient M1 transgene exhibit severe alopecia, a hair loss phenotype. Skin stem cells from these animals were cultured in vitro and analyzed by a cell proliferation assay. Our results indicate that cells derived from wild-type and sumoylation-deficient M1 animals proliferate similarly for the first 96-hours in culture. Cultures prepared from sumoylation-deficient M1 animals deteriorate subsequently. Future studies will identify the mechanism by which Sp3 sumoylation regulates stem cell proliferation.
Mohammed Alshareef, B.S. [1], Nicholas Metrakos, B.S. [1], Eva Juarez-Perez, B.S. [1], Fadi Azer [2], Fang Yang [3]
[1] Biomedical Engineering, University of South Carolina, Columbia, SC
[2] Biomedical Engineering, Vanderbilt University, Nashville, TN
[3] Mechanical Engineering, University of South Carolina, Columbia, SC
[4] WJB Dorn Veterans Affairs Medical Center, Columbia, SC
Background: Circulating tumor cells become an interesting target for separation and isolation in cancer diagnosis. However, separation of one type of cancer cells from other types of cancer cells is very difficult, because they share similar size and are epithelia cells. Therefore, separation and isolation of one target cancer cell from other types of cancer cells is highly desirable in early cancer detection and cancer research. Method: The present work demonstrates the use of a dielectrophoretic lab-on-a-chip device in effectively separating different cancerous epithelial cells for application in circulating tumor cells (CTC). This study uses dielectrophoresis (DEP) to distinguish and separate human breast cancer (MCF-7) cell line from another cancer cell line, colon cancer (HCT-116). The DEP responses for each cell type were measured against AC electrical frequency changes in solutions with different conductivities. Results: It was determined that increasing the conductivity directly correlated with an increasing frequency value corresponding to the first cross-over (no DEP force) point in DEP spectra. Difference in the cross-over frequency for each cell type was leveraged to determine the frequency at which the two cells would experience significantly different DEP forces for separation. Using a microfluidic DEP sorter with optically transparent electrodes, MCF-7 and HCT-116 were successfully separated from each other under a 3.2 MHz frequency in a 0.1X PBS solution. Further experiments were conducted to characterize the separation efficiency (enrichment factor) by changing experimental parameters (AC frequency, voltage and flow rate). Conclusion: This work shows the high specificity of the described DEP cell sorter for distinguishing cells with similar characteristics for potential diagnostic applications in CTC enrichment.
Christopher Gardner [1], Russell Gorga, Ph.D [1], Yeoheung Yun, Ph.D [2], Jag Sankar, Ph.D [2]
[1] Department of Biomedical Engineering, NC State University, Raleigh, North Carolina
[2] NSF ERC for Revolutionizing Metallic Biomaterials, NC A&T State University, Greensboro, North Carolina
Current advances in materials science aim at replacing biostable orthopedic implants, including stainless steel, titanium, and Co-Cr alloys, with biodegradable and bioactive implant materials, such as magnesium alloy. In order for magnesium to be a viable biodegradable alternative to current load bearing orthopedic implants, its corrosion rate must be adjusted in vivo to ensure that the implant retains adequate mechanical integrity until the healing process is complete. Modifying the surface of the magnesium has been shown to reduce its corrosion rate both in vivo and in vitro. However, nonwoven polyester nanofiber scaffolding used in tissue engineering has yet to be explored as a potential corrosion resistant coating for magnesium implants. Poly-D,L-Lactic Acid (PLA) was chosen as the coating material due to its mechanical, hydrophobic and biodegradable properties, and was processed by electrospinning to yield a topographical landscape of nanofibers similar to the bone extracellular matrix, which has been shown to promote cell adhesion and proliferation. The objective of this study was to apply the process of electrospinning to coat a magnesium alloy surface and characterize its corrosion resistance in vitro. Results of a DC polarization scan of a WE43 magnesium electrode coated with electrospun PLA exhibited a corrosive current more than eight times smaller than the bare WE43 electrode.
Steven W. Lee [1], Bryan C. Thorne [1], Shayn M. Peirce, Ph.D. [1]
[1] Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
The process of leukocyte trafficking plays a key role in fighting infectious pathogens. The trafficking of leukocytes to an inflamed site and the release of cytokines, destruction of abnormal cells, and engulfment of foreign materials is critical in the maintenance of health. The objective of this study is to understand the effects of shear stress and blood flow velocity on the trafficking of leukocytes and their correlations. By understanding these effects, we are able to gain new insights into the mechanisms regulating this complex process under both normal and inflammatory conditions, which may lead to the possibility of suggesting new therapeutic avenues for inflammatory diseases. To conduct the study, colonies of Cx3CR-1 GFP/+ mice were raised and underwent both a dorsal skinfold window chamber and jugular vein cannulation surgeries. The dorsal skinfold window chamber enabled the visualization of leukocyte activities within a well-defined vascular network. The jugular vein cannulation procedure enabled the injection of fluorescent microspheres to study blood flow velocity and flow rate. Data was collected from the mice at the time of surgery, post-surgical day three, and post-surgical day three after TNF-alpha treatment. Digital intra-vital fluorescence video microscropy was used to analyze both leukocyte and microsphere activities. The results from this study indicate that leukocytes’ rolling velocity have direct relationships with both shear stress and flow velocity. Moreover, leukocyte rolling flux fraction, or the number of rolling leukocytes expressed as a percent of all leukocytes traveling through the vessel, was observed to have indirect relationships with shear stress and flow velocity. This suggests that shear is perhaps the best predictor of rolling flux fraction and rolling velocity. Future studies will identify the specific roles that shear stress and blood flow velocity have in maintaining a well-controlled inflammatory response and how they can contribute to pathological processes, such as plaque formation in atherosclerosis.
Steven W. Lee [1], Bryan C. Thorne [1], Shayn M. Peirce, Ph.D. [1]
[1] Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
The process of leukocyte trafficking plays a key role in fighting infectious pathogens. The trafficking of leukocytes to an inflamed site and the release of cytokines, destruction of abnormal cells, and engulfment of foreign materials is critical in the maintenance of health. The objective of this study is to understand the effects of shear stress and blood flow velocity on the trafficking of leukocytes and their correlations. By understanding these effects, we are able to gain new insights into the mechanisms regulating this complex process under both normal and inflammatory conditions, which may lead to the possibility of suggesting new therapeutic avenues for inflammatory diseases. To conduct the study, colonies of Cx3CR-1 GFP/+ mice were raised and underwent both a dorsal skinfold window chamber and jugular vein cannulation surgeries. The dorsal skinfold window chamber enabled the visualization of leukocyte activities within a well-defined vascular network. The jugular vein cannulation procedure enabled the injection of fluorescent microspheres to study blood flow velocity and flow rate. Data was collected from the mice at the time of surgery, post-surgical day three, and post-surgical day three after TNF-alpha treatment. Digital intra-vital fluorescence video microscropy was used to analyze both leukocyte and microsphere activities. The results from this study indicate that leukocytes’ rolling velocity have direct relationships with both shear stress and flow velocity. Moreover, leukocyte rolling flux fraction, or the number of rolling leukocytes expressed as a percent of all leukocytes traveling through the vessel, was observed to have indirect relationships with shear stress and flow velocity. This suggests that shear is perhaps the best predictor of rolling flux fraction and rolling velocity. Future studies will identify the specific roles that shear stress and blood flow velocity have in maintaining a well-controlled inflammatory response and how they can contribute to pathological processes, such as plaque formation in atherosclerosis.
Melissa Dunphy [1], Kaitlin Grove [1], Molly Townsend [1], Nadine Luedicke [1], Elizabeth Burghardt [1]
[1] Department of Bioengineering, Clemson University, Clemson, SC
The Creative Inquiry (CI) program at Clemson University serves to involve undergraduates in team-based research and engaged learning. This CI group focuses on re-engineering a simulator for the Central Venous Catheterization (CVC) procedure. This procedure involves the insertion of a large catheter through a large vein in the neck or chest, such as the subclavian or jugular, and into the heart when the patients requires a large influx of drugs, such as in the case of severe traumas. With the target veins so close to the lungs and vital arteries, precision is necessary and imprecision is fatal. Unfortunately, it is particularly challenging for students to learn this procedure and often is practiced but novice students on live, unsuspecting, patients as current simulators are ineffective and inaccurate.
These currently available simulators are expensive and inconvenient, and often they are not anatomically accurate, which lead to training students improperly. Some of the aforementioned shortcomings with existing designs include the complete lack of a rotatable head, necessary anatomical landmarks for accurate needle placement, and a mechanism for proper patient orientation prior to the procedure. Through our group’s collaboration with an expert in medical simulation, we have addressed these issues and are currently seeking patents on our improvements to the simulators and examining possible outlets of distribution. Our novel design not only addresses the shortcomings of current simulators on the market but it also includes additional capabilities that have specifically been requested by clinicians. Our training simulator is ultrasoundable and can replicate both the pulsing of the arteries and the expanding of the veins under changes in fluid pressure. In addition, our simulator comes with training software which allows for tracking of students as they progress through the curriculum. Our next steps are to starting useability testing of our beta test prototype and secure initial seed funding for a startup venture.
Lance O. Co Ting Keh, B.S. [1], Ana M. Chupungco [3], Jose P. Esguerra [2]
[1] Department of Biomedical Engineering, Duke University, NC
[2] Department of Physics, University of the Philippines
[3] Research Department, Philippine Science High School
Three methods of nonlinear time series analysis, Lempel-Ziv complexity, prediction error and covariance complexity were employed to distinguish between the electroencephalograms (EEGs) of normal children, children with mild autism, and children with severe autism. Five EEG tracings per cluster of children aged three to seven medically diagnosed with mild, severe and no autism were used in the analysis. A general trend seen was that the EEGs of children with mild autism were significantly different from those with severe or no autism. No significant difference was observed between normal children and children with severe autism. Among the three methods used, the method that was best able to distinguish between EEG tracings of children with mild and severe autism was found to be the prediction error, with a t-Test confidence level of above 98%.
Matthew D. Cupelli, B.S. [1], Delphine Dean, Ph.D [1]
[1] Department of Bioengineering, Clemson University, Clemson, South Carolina
There are forces in the body that are constantly pushing and pulling on our bones and teeth. Wolff’s Law says that bones will adapt to the loads applied to them. If the forces applied to a cell can impact the growth patterns, this knowledge could be used for applications in tissue engineering. The aim of my research project is to determine the effect of compression on dental pulp stem cells. Cartilage has been tested because it is also continually loaded and unloaded with forces. However, dental pulp stem cells have not been tested to see the effects of compression.
The first step in the process of testing the response of stem cells to compression was to build a compression chamber. A custom cell culture dish needed to be fabricated. A computer model was designed on Solidworks and taken to the Clemson Machining and Technical Services shop to fabricate. Following fabrication of the chamber, a protocol for forming gels to place under compression was needed. Using past literature, a protocol was formed and tested. In a conical tube, 800 µL of type 1 collagen at a concentration of 1mg/mL was mixed with 100 µL of pH 9 HEPES and 100 µL of 10X MEM. 60,000 osteoblast cells were added to the mixture and it was transferred onto glass coverslips in the 6-well culture dish at 165 µL/coverslip and allowed to incubate to cure the gel.
The custom top was made of 316L Stainless Steel, and it has a mass of 632 grams; therefore, a pressure of 0.93 g/mm2 will be applied to the collagen gels. All components of the cell compression chamber work as designed, and are currently being used for testing. No data has been collected yet.
The next steps are to culture dental pulp stem cells and grow them in the collagen gels inside the compression chamber. Different loading frequencies will be used along with different loading weights. Alkaline phosphatase and BCA assays will be performed on the samples at each time point and some will be fixed and stained for confocal imaging. Also, a duplicate compression chamber will be fabricated using an acrylic polymer to replace stainless steel. This change in materials will reduce the base weight of the custom device and allow for more variability in testing weights. Overall, this project could lead to more knowledge about the differentiation of stem cells.
Alessandra C. Grasso, B.S. [1], Keerthi Vijayakumar, B.S. [1], Lauren A. Griggs, B.S. [1]
[1] Department of Electrical Engineering, University of Virginia, Charlottesville, Virginia
[2] Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
The creation of an ideal nanofibrous scaffold for tissue engineering has been the inquiry of many scientists in the research community. In mimicking the extracellular matrix of various tissues, nanofibrous scaffolds seek to provide an increase in the regeneration speed as well as the functional recovery of damaged tissues through supportive adhesion, appropriate guidance, and cell signaling. Through the process of electrospinning, repulsive forces are used to stretch nanofibers and arrange them in an aligned array. We have studied various methods of electrospinning and found that dielectric collectors provide the ideal alignment needed for tissue regeneration. We will continue to optimize electrospinning conditions for the dielectric collector. Our experiments will focus on seeding fibroblast, Schwann, and PC12 nerve cells on fibers fabricated on wood, aluminum, and magnetic collectors with varying gap length to determine the best cell morphology. A 85:15 poly(lactide-co-glycolide acid) (PLGA) polymer will be dissolved in THF (tetrahydrofuran) and DMF (dimethylformamide) solvents at ratio of 3:1 to produce small, stretchy fibers. The fibers will then be pumped through an electrically charged needle and stretched across the gap of the grounded collector to produce an aligned array of fibers. We hypothesize that nanofibers aligned at patterned plate collectors with dielectric gaps will follow the electric field lines due to the balance of attractive transverse forces across the gap versus repulsive lateral forces between adjoining un-discharged fibers. The ultimate goals are to understand conditions for routinely synthesizing a thick mesh of highly aligned nanofibers and to compare fibroblasts to Schwann and PC12 nerve cells’ morphology on the scaffolds.
Key Words: nanofibrous scaffold, electrospinning, cell morphology, dielectric, Schwann cells, PC12 cells, fibroblasts
Darien B. Davda, B.S. [1], Jui-Heng Tseng, M.S. [1], Chen Suo, Ph.D. [1], Jie Gao, Ph.D. [2], Melissa Moss, Ph.D. [1]
[1] Department of Biomedical Engineering, University of South Carolina, Columbia, South Carolina
[2] South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina
Alzheimer's disease (AD) is the most common form of debilitating dementia; it produces symptoms of long-term memory loss, linguistic incapability, and chronic cognitive failure. Biochemical studies have shown that the amyloid-beta protein (Aâ) forms aggregates that deposits across the brain and these aggregates are fundamental to the disease symptoms. Aggregation of monomeric Ab begins with a lag phase following by rapid growth during which soluble aggregates are created. These aggregate intermediates eventually form fibrils, which deposit as Aâ plaques in AD patient brains. In addition, AD brains exhibit deficits in the neurotransmitter acetylcholine. Currently, FDA approved drugs reduce Acetylcholinesterase (AChE) activity in order to improve AD symptoms. However, AChE inhibitors could additionally have the potential to stop Aâ aggregation. This project evaluates the inhibitory potential of several derivatives of a known AChE inhibitor on Aâ aggregation. Ab monomer was aggregated in the presence of NaCl, to promote nucleation, and excess molar quantities of AChE inhibitors. The effect of inhibitors upon both nucleation, indicated by an extension of the lag time to aggregate appearance, and the extent of aggregation was determined. Effective inhibitors were identified as those that delayed nucleation or curtailed the extent of fibril formation.
David I. Ader [1], Caroline L. Whitaker B.S. [1]
[1] Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
In a previously published paper by Bernimoulin et al (2003), it was reported that the inclusion of the Core-2 branching of PSGL-1 was required for optimal L-Selectin binding to PSGL-1. However, based on recent unpublished work (Whitaker, Ader 2011), we believe that the Core-2 branching may actually not be necessary for adhesion. The purpose of this project will be to look at the cell lines used, and to determine if the previous paper’s conclusion was false. If the hypothesis proves true in the favor of a ‘Core-1 extension,’ then the conclusions of Bernimoulin et al (2003) will then be false, showing, in fact, a different result, and concludes in a new feature of the PSGL-1 molecule.
Devjani Saha, M.S. [1], Ferdinando A. Mussa-Ivaldi, Ph.D [1]
[1] Sensory Motor Performance Program, Rehabilitation Institute of Chicago
[2] Department of Biomedical Engineering, Northwestern University, Chicago, Illinois
[3] Department of Physiology, Northwestern University, Chicago, Illinois
How the brain controls for movement is the subject of ongoing controversy. One alternative is that it solves an inverse dynamics problem, in which forces and torques are explicitly computed in order to move the limb through a planned trajectory in space. Another alternative is the equilibrium point hypothesis (EPH), in which muscles are represented as nonlinear springs with adjustable resting lengths and stiffness. Numerous studies have investigated the issue of whether EPH or inverse dynamics underlies movement control. The goal of this study is not necessarily to refute or corroborate either mechanism for the control of human movement. Instead we wish to examine whether these two mechanisms can be applied to movement control of a myoelectric device. We designed a myoelectric task, in which subjects were asked to control the movement of a virtual mass in a 2D plane by activating a set of four muscles. Muscle activity was transformed either into a force or was used to modulate the force-length characteristics of opposing springs connected to the mass. The first paradigm tested how well subjects apply inverse dynamics for movement control, while the second paradigm examined control via the EPH. The data indicate that the rate of learning was not significantly different between the two controllers. However, with the equilibrium point interface subjects demonstrated more accurate feedforward movements in trials without visual feedback, simultaneous control of two degrees of freedom, and faster transitions to the target. These gains can be attributed to the elastic properties of the equilibrium point controller, which provide stability during movement and in the presence of unexpected perturbations.
Elliott D. Mappus [1], Amanda K. Nguyen [1], Tyler G. Harvey [1], Brian D. Peterson [1], Erik A. Hammes [1]
[1] Department of Bioengineering, Clemson University, Clemson, South Carolina
In wound healing, fibroblasts migrate to the site of injury and serve an integral role in repairing and healing the wound. As tissue engineering develops into a potential tool for regenerating damaged and diseased tissue, understanding of the fibroblast migration mechanism and the effects of fibroblast growth factor is vital. Cellular navigation through the extracellular matrix in vivo requires recognition and avoidance of obstacles. Directed cell migration through chemotactic signaling offers one explanation for how cells arrive at their intended destination; however, this explanation cannot predict the behavior of cells when presented by 3 dimensional objects with additional signaling.
In order to study the fibroblast migration mechanism, we examined the process of wound healing interrupted by a physical barrier when two leading edges of fibroblasts are separated by a maze of polydimethylsiloxane (PDMS). To construct the microfluidic mazes we laser printed maze patterns onto Shrinky Dink plastic and then applied heat to produce plastic molds with raised maze patterns. The molds were then used to cast the PDMS mazes.
The PDMS cellular maze was attached to the bottom of a cell culture dish and 3T3 fibroblasts were plated on both side of the access points. After the cells grew to confluence outside of the maze, the maze was opened with a surgical blade allowing entrance to the maze. Observation of the growth of the fibroblasts occurred for 48 hours after opening of the entrance to the maze.
The results of these studies will be compared to mathematical models of cell growth in response to chemical soluble factors. Our long-term goal is to build a model to predict cell growth and migration in 3D that can be used to help design novel wound healing therapies. These initial studies are focused on fibroblast growing in response to 2D confinement and guidance; our next step will be to design a well-characterized patterned maze system for the cells to grow in a 3D environment.
Ying Wang [1], Abigail Fulp [2], John Johnson [3], Michael A. Sutton, Ph.D. [4], Susan M. Lessner, Ph.D. [3]
[1] Biomedical Engineering Program, University of South Carolina, Columbia, SC;
[2] Dept. of Biomedical Eng., North Carolina State University, Raleigh, NC
[3] Dept. of Cell Biology and Anatomy, School of Medicine, University of South Carolina, Columbia, SC
[4] Dept. of Mechanical Engineering, University of South Carolina, Columbia, SC
Atherosclerotic plaque rupture is a major cause of myocardial infarction and stroke. The adhesive strength of the bond between the plaque and the vascular wall, measured as local energy release rate, G, was used for quantitative plaque stability estimation. We hypothesize that adhesive strength varies with plaque composition in mice of different genotypes, and that it correlates with histological features associated with plaque stability, such as collagen deposition and macrophage content in lesions. Mice which are genetically deficient in matrix metalloproteinase 12 (MMP12), a macrophage elastase, have previously been shown to demonstrate altered lesion composition.
To estimate the energy release rate, G, peeling tests were performed on aortic plaques from apolipoprotein E knockout (apoE KO) and apoE MMP12 double knockout (apoE MMP12 DKO) male mice maintained on a Western diet for 8 months. For plaques in apoE KO mice, our experimental values for G averaged 24.5 Joule/m2. For plaques in apoE MMP12 DKO mice, G values averaged 13.7 J/m2. A two-tailed Wilcoxon test showed a significant effect of genotype on measured G values (p<0.05). Histological studies confirmed that the plaques delaminated at the interface between the plaque and the underlying internal elastic lamina (IEL) in both strains of mice. Quantitative image analysis of Picrosirius Red-stained tissue sections demonstrated a positive linear correlation between local collagen content of lesions and G values in both strains of mice (p<0.01). The average collagen content for plaques in apoE KO (17.1%) and apoE MMP12 DKO mice (13.6%) was not significantly different. Immunohistochemical staining showed that macrophage content of aortic plaques is neither significantly correlated with G values nor significantly different between these two strains of mice. Overall, our results suggest that plaques adhere more strongly to the underlying IEL in apoE KO mice than in apoE MMP12 DKO mice.
Matthew B. Kofoed B.S. [1], Christy L. Franco Ph.D [2], Jennifer L. West Ph.D [2]
[1] Department of Biomedical Engineering, Clemson University, Clemson, SC
[2] Department of Bioengineering, George R. Brown School of Engineering, Rice University, Houston, Texas
Stroke is the third leading cause of death in the United States, and more than 795,000 Americans experience non-fatal strokes annually. Strokes are characterized by local tissue death which results from occluded blood flow to specific regions of the brain. Previously stroke victims have hoped to regain only a reduced amount of prior brain function through physical and mental therapies. There is a need for more targeted treatment to reverse the damage caused by neurological injuries and diseases.
Neural stem cell (NSC) therapies have the potential to meet this need by stimulating the growth of new healthy tissue in place of necrotic tissue in stroke victims. Controlling and directing the differentiation of NSCs in degradable Poly(ethylene Glycol) (PEG) hydrogels may provide patients with much needed sources of neurologic donor material. Unmodified PEG can be cross-linked to form a bio inert polymer matrix. This matrix may be modified before cross-linking with the addition of bio-active components such as cyclic RGD to promote cell adhesion. NSCs may be seeded on the surface or encapsulated within these modified PEG hydrogels allowing for effective mimicking of the in vivo extracellular matrix.
The first objective of this work was quantifying the percentage of peptide incorporation in hydrogels. Gels were made with set concentrations of PEG-WRGDS. Characteristic UV absorption by tryptophan in PEG gels was used to measure peptide incorporation. It was found that 63% of the initial peptide was incorporated in the gel matrix.
The second objective of this study was to determine whether the incorporation of various concentrations of Fibroblast Growth Factor (FGF) within the hydrogel matrix promoted proliferation of NSCs. Three concentrations of growth factor tethered to PEGDA in solution were used to prepare gels and cell proliferation was measured. Patterned gels were also fabricated to observe spatial control of cell proliferation within a single gel system. CTX0E03 cells were seeded on the surface of the gels and allowed to proliferate for three days before fixation. The cells were stained for Ki-67 and DAPI to quantify proliferation.
Initial evaluation of the cell-seeded hydrogels suggests that as FGF concentration increases, so does CTX0E03 proliferation. The results of this experiment suggest that modification of PEG hydrogels with bio-active components may be a viable method of controlling NSC differentiation and proliferation.
Matthew B. Kofoed B.S. [1], Christy L. Franco Ph.D [2], Jennifer L. West Ph.D [2]
[1] Department of Biomedical Engineering, Clemson University, Clemson, SC
[2] Department of Bioengineering, George R. Brown School of Engineering, Rice University, Houston, Texas
Stroke is the third leading cause of death in the United States, and more than 795,000 Americans experience non-fatal strokes annually. Strokes are characterized by local tissue death which results from occluded blood flow to specific regions of the brain. Previously stroke victims have hoped to regain only a reduced amount of prior brain function through physical and mental therapies. There is a need for more targeted treatment to reverse the damage caused by neurological injuries and diseases.
Neural stem cell (NSC) therapies have the potential to meet this need by stimulating the growth of new healthy tissue in place of necrotic tissue in stroke victims. Controlling and directing the differentiation of NSCs in degradable Poly(ethylene Glycol) (PEG) hydrogels may provide patients with much needed sources of neurologic donor material. Unmodified PEG can be cross-linked to form a bio inert polymer matrix. This matrix may be modified before cross-linking with the addition of bio-active components such as cyclic RGD to promote cell adhesion. NSCs may be seeded on the surface or encapsulated within these modified PEG hydrogels allowing for effective mimicking of the in vivo extracellular matrix.
The first objective of this work was quantifying the percentage of peptide incorporation in hydrogels. Gels were made with set concentrations of PEG-WRGDS. Characteristic UV absorption by tryptophan in PEG gels was used to measure peptide incorporation. It was found that 63% of the initial peptide was incorporated in the gel matrix.
The second objective of this study was to determine whether the incorporation of various concentrations of Fibroblast Growth Factor (FGF) within the hydrogel matrix promoted proliferation of NSCs. Three concentrations of growth factor tethered to PEGDA in solution were used to prepare gels and cell proliferation was measured. Patterned gels were also fabricated to observe spatial control of cell proliferation within a single gel system. CTX0E03 cells were seeded on the surface of the gels and allowed to proliferate for three days before fixation. The cells were stained for Ki-67 and DAPI to quantify proliferation.
Initial evaluation of the cell-seeded hydrogels suggests that as FGF concentration increases, so does CTX0E03 proliferation. The results of this experiment suggest that modification of PEG hydrogels with bio-active components may be a viable method of controlling NSC differentiation and proliferation.
Melissa Henderson [1]
[1] Department of Biomedical Engineering, University of South Carolina, Columbia, South Carolina
Cardiac malformations are the most common form of human birth defects. Among these malformations, those of the cardiac valves are the most common and deadly. Recently, an avian model of one of these cardiac birth defects, Tetralogy of Fallot (TOF), has been developed (Dyer and Kirby, 2009). In this model the administration of an inhibitor of the sonic hedgehog protein, cyclopamine, results in cardiac malformations associated with TOF. Such defects include pulmonary atresia or stenosis, septal defects, and ventricular hypertrophy. These defects appear to also include aberrant expression of the elastin protein. The correct expression and localization of this protein is critical to the proper function of the heart. The purpose of this study is to map the mislocation of the elastin protein in representative Tetralogy of Fallot conditions and determine its contribution to reduced functionality of the heart. One TOF chick embryonic heart at day 16 and one chick embryonic control heart at day 16 were sectioned, prepared and stained using Weigert’s Elastin Stain. Afterwards, pictures were taken using Axiovision software. Two models isolating the myocardium and elastin within the pulmonary and aortic valves were created and the elastin was quantified using AMIRA technology. It was found that there are noticeable differences between the TOF and control heart when the valves are isolated. Supported by material statistics, the ratio of pulmonary elastin to myocardium is greater in a TOF heart resulting in a thickened pulmonary valve. Future directions include improving accuracy and mapping blood flow through the thickened valves.
Erika K. Jelen, B.S. [1], Jhilmil Dhulekar [1], Thomas L. Moore, B.S. [1], Frank Alexis, Ph.D [1], Chris Recknor, Ph.D [2]
[1] Department of Bioengineering, Clemson University, Clemson, SC
[2] United Osteoporosis Center, Gainesville, GA
Because of an increase in mortality after primary fractures in patients older than 60 years; osteoporotic fracture is a heavy burden on the U.S. economy. This increase in mortality is even higher for patients with repeated vertebral and non-vertebral fractures that occur within 5 years after the first fracture. Although major advances in the understanding of bone biology and osteoporosis have resulted in better diagnosis and treatment, there is clinical evidence that there is a need for safe and effective therapy to reduce the risk of primary and repeat fractures. An innovative area in drug delivery is the use of functionalized nanoparticles to target specific cells or tissues. The first step to develop nanoparticles targeted to bone is to identify and test selecting ligands that have binding affinity in-vitro, ex-vivo, and in-vivo. This research focused on biomolecules with preferential binding to hydroxyapatite (HA), which is the mineral component of bone. The specificity and affinity of the therapeutic delivery could increase the amount of drug delivered to the bone to improve current methods to treat bone diseases. Fluorescent biomolecules were competitively tested using human bone tissue samples, HA discs, chicken bone tissue and mouse bone tissue. To quantify the binding affinities of the fluorescent peptides, we used the IVIS Lumina XR imaging system equipped with X-ray and fluorescent detection. The results indicated successful peptide binding in both experiments—human and animal bone tissue samples. Quantitatively, the results show significant differences of biomolecules affinity to bone. The applications for this research include osteoporosis, arthritis, and microgravity-induced bone density loss.
Britton McCaskill, M.S. [1], Maglin Halsey, B.S. [1], Kaitlyn Harfmann, B.S. [1], Andrea Dicks, B.S. [1], Tyler Youngman, B.S. [1]
[1] Department of Bioengineering, Clemson University, Clemson, South Carolina
According to the Global Health Workforce Alliance in 2010, Africa was in need of an additional 1.5 million health care workers to supplement the current workforce. Madaktari Africa and Engineering World Heath, two organizations with whom our group is currently working, are attempting to develop a sustainable system for training this much-needed medical staff and to design novel medical devices that are both affordable and effective for the developing world, respectively.
At Clemson University, our Creative Inquiry, a group of undergraduates leading research, is working to address some of the key issues prevalent in these countries, specifically Tanzania, ranging from lack of appropriate medical devices to inadequate disease treatments and prevention. More specifically, this Creative Inquiry stemmed from work to develop a heating blanket for neonates that would provide a safer, more reliable option to the broken incubators or heated rooms that currently function to maintain appropriate neonate body temperature. Our connection to Tanzania results from our partnering with Madaktari Africa, who is working there to train doctors and improve overall medical conditions.
Currently, we are in the process of researching and designing several items, including the heating blanket previously mentioned, that we plan to test and implement in the near future. Other projects include alternative neck braces, a bacterial tester for water, a dialysis filter, and a cost effective glucose sensor. We also are continuing to develop our relationship with the doctors and other professionals who can aid us in our endeavors and provide the resources we need to succeed.
Na Li [1], Jay Potts [1]
[1] Cell biology and anatomy department
[2] School of Medicine
[3] University of South Carolina
[4] Columbia
[5] South Carolina
During heart valve development, epithelial-mesenchymal transformation (EMT) is a key process in the formation of the developing valve. EMT leads to the generation of mesenchymal cells that will eventually become the interstitial cells (fibroblasts) of the mature valve. During EMT, the cell architecture and cell motility change dramatically as well as changes in various signaling pathways.
How this cytoskeletal organization is regulated during EMT is still unknown. In this study, we conducted comprehensive study on a focal adhesion protein zyxin, its expression, localization and function in EMT during chick AV valve formation. Using qRT-PCR we found that zyxin was constantly expressed in AV valve region during different stages of valve development. Immunofluorescence staining and in situ hybridization studies showed that zyxin was localized in both myocardium and endocardium layers in AV region as well as mesenchymal cells created during the EMT process. To further examine the role of zyxin in EMT during AV valve formation, we used chick AV valve tissue and 3-D collagen gel ex vivo culture system. Both siRNA knockdown and over-expression of zyxin were performed and showed consistent results suggesting that zyxin plays a role as a negative regulator for cell migration and differentiation during the EMT process in chicken AV valve formation. In conclusion, we demonstrated the spatiotemporal expression pattern of zyxin in chick AV valve formation for the first time and also explored the role of zyxin in cell migration and differentiation in EMT.
Kevin Keith [1], Tyler Youngman [1], Ben Jacoby [1], Jovan Jovanovich [1]
[1] College of Material Science, Nanyang Technological University, Singapore
Statement of Purpose: The purpose of this research was to uncover useful methods for synthesizing biologically functional Hyaluronic Acid (HA) hydrogels. A thorough literature review revealed that very few methods exist to create these hydrogels, and those that do are often incompatible for sustained use in vivo (toxic crosslinker, required highly alkaline environment, etc.). In addition to investigating possible biologically compatible linkage methods, determining the characteristics and behavior of the HA hydrogels were also an important project objective. HA is also an attractive building block for new biocompatible and biodegradable polymers with particularly attractive applications in drug delivery. Chemical modification allows the physicochemical properties and in vivo residence time of HA to be tailored to specific applications while retaining its natural biocompatibility, biodegradability, and lack of immunogenicity.
Results: Results indicate that the initial HA concentration is the driving force behind HA release, whereas the PEGDA content plays no statistically significant role. From a HA percentage release perspective, significantly more is released for an initial HA concentration of 0.5 % than for the 1 and 2 % HA solutions. The influence of PEGDA may however be significant in the longer term, as one might expect that the PEGDA content, and thus density of the PEG network, plays a role in moderating HA release. The swelling ratios after 24 h and 7 days are show in Figure 2, and are seen to vary between 5 and 20. This may be accounted for by the previous HPLC measurements, which concluded that 30-50 % of the total HA may leach out by day 7. Accordingly, regardless of the amount of HA, a higher PEGDA content implies lower swelling ratio, as expected due to the higher crosslinking density.
Conclusions: The objectives of this project were to synthesize and characterize novel hyaluronic acid (HA) based hydrogels for potential biomedical applications. The focus of the study was to determine the influence of HA and PEGDA content on HA release, swelling and rheological properties of the hydrogel. Results indicated that there was no statistically significant difference between the PEGDA 575 and 700 hydrogels, and that hydrogels with a greater initial HA content shall release more HA in absolute terms during the same period of time. In percentage release terms, nonetheless, the initial concentration does play in governing the release mechanism. The swelling behavior of the hydrogels was proved to be governed only by the PEGDA content, as expected since it is the PEDGA that forms the hydrogel network.
Pallavi Ramnarain, M.S. [1], Nyimas Y. Isti Arief [1], Paul A. Wetzel, Ph.D [1], Rita H. Pickler, Ph.D [2], Mary Jo E. Grapp [3]
[1] Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia
[2] Center for Professional Excellence, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
[3] Department of Adult Health and Nursing Systems, Virginia Commonwealth University, Richmond, Virginia
Heart rate variability (HRV) is a noninvasive measurement of cardiac and autonomic nervous system functionality. It has become a tool of clinical and research significance. Respiration has been widely accepted as a main contributor to the high frequency peak in HRV power spectra. Respiratory induced heart rate variability is referred to as respiratory sinus arrhythmia (RSA).Frequency domain analysis is commonly used in heart rate variability as an indicator of physiological state. This paper examines heart rate in conjunction with respiratory rate to investigate the evidence of their relationship in the frequency domain across two populations: preterm infants and mechanically ventilated adults. Correlation analysis was performed on power spectral density estimates derived from heart and respiratory rate tachograms. Although the results obtained showed a weak correlation for infants (R = 0.44, SD = 0.19, p = 0.002) and a modest correlation for adults (R = 0.68, SD = 0.18, p < 0.0001), they were consistent with expectations for these particular populations.
Trey Poole [1], Laura Reese [1], Brandon Mattix [1], Dan Simionescu, Ph.D [1], Frank Alexis, Ph.D [1]
[1] Department of Bioengineering, Clemson University, Clemson, South Carolina
Every year, thousands of patients are in need of organ transplants; however, their demand far outweighs the available supply. Tissue engineering is a multidisciplinary field whose aim is to develop organ replacements to restore lost functionality. Several problems face tissue engineering including both economic and intrinsic constraints, which are expected to limit biofabrication of completely functional organ replacements. A more realistic goal is to develop functional vascularized tissue engineered organ constructs that are capable of restoring essential functionality. Options for replacing damaged vasculature currently include allografts, xenografts, and synthetic grafts. Unfortunately, their utility is limited to vessels with diameters greater than six millimeters and to high flow rate environments. Furthermore, most vasculature disease is associated with vessels whose diameter is less than six millimeters. This results in a high incidence of occlusion where current vascular grafts are used that are not designed for these conditions. As such there is great need for engineered linear and branched blood vessels as well as for biofabrication techniques utilizing novel processes such as self-assembly.
The objective of the proposed research is to integrate magnetic properties into the fabrication of cell-based spheroids for magnetic force-assembly. Initial studies have shown that we are able to: fabricate magnetic cell-based spheroids; avoid iron oxide nanoparticle toxicity associated with long exposure times; control the cellular localization of iron oxide; and magnetically manipulate spheroids. Future studies will investigate the fabrication of linear and branched vasculature utilizing magnetic properties to induce maturation and phenotype.