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ABSTRACT: It has been predicted that the highest demand for engineers through the year 2008 will be in the biomedical sector. To meet these needs, the objective of the present study was to increase undergraduate exposure and interest in BME through a research experiences for undergraduates (REU, sponsored by the National Science Foundation) site at Purdue University (https://engineering.purdue.edu/BME/REU/). In achieving these goals, 11 undergraduate student participants conducted BME-related research on the Purdue campus during the summer of 2004. Of these students, 9 were females or underrepresented minorities and 7 had not had hands-on BME experiences prior to the REU program. Each REU student visited 3 BME industries, observed the operating room/clinic, and partook in a bioethics series. In addition, research progress was conveyed through weekly lab meetings and presentation of both a research poster and a formal, 30-minute long, research seminar. To date, cutting-edge research conducted over this and previous summers (2001-2004 in total) has resulted in over 20 manuscripts and over 35 abstracts presented at national BME-related conferences. Finally, survey results provided evidence that REU participants were extremely pleased with the experience and were more likely to enroll in BME graduate programs at the conclusion of the REU program.
Bioengineering Conference, 2005. Proceedings of the IEEE 31st Annual Northeast; 05/2005
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ABSTRACT: Cardiovascular diseases result in altered endothelial cell functions because of changes in blood flow properties. To understand the relationship between cell environment and behavior, endothelial cell expression of key genes (COX-2, ecNOS, and PDGF-B) was analyzed following exposure to defined mechanical and chemical conditions. Cells were exposed to control medium, control medium and physiological flow, control medium and physiological pressures, control medium and pathological pressures, flow-conditioned medium, flow-conditioned medium and physiological flow, or flow-conditioned medium and physiological pressures. Endothelial cells were sensitive to both their chemical and mechanical environments; for example, while flow, pressure, and flow-conditioned medium each individually affected gene expression, this expression was most dramatically altered when cells were simultaneously exposed to mechanical and chemical stimuli. Interestingly, gene expression following pressure exposure was always less than that following flow. Next, this study began to investigate endothelial cell behavior under pathological flows using a stenotic glass tube with dimensions similar to the carotid artery. Particle image velocimetry (PIV) measurements were utilized to characterize flow within such tubes; in the future, these flow patterns will be correlated with endothelial cell gene expression. Ultimately, these flow-cell relationships may aid in predicting sites of disease expansion downstream of a stenosis.
Bioengineering Conference, 2005. Proceedings of the IEEE 31st Annual Northeast; 05/2005
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ABSTRACT: Kidney damage and/or failure caused by urinary obstruction affects thousands of patients each year. It has been hypothesized that hypoxia and/or elevated levels of hydrostatic pressure within the kidney during obstruction contribute to renal failure. However, little research has been performed to verify this claim. Investigators have examined the effects of a single stimuli, hypoxia or elevated pressure, on renal cells and have observed functional changes, including cytoskeletal rearrangement However, during obstruction in vivo, these insults are not likely to be present in isolation. In fact, it may be the synergistic effect of these combined stimuli that leads to renal failure. Therefore, an optically compatible chamber has been designed and constructed to monitor and quantify in vitro cellular changes resulting from the combined stimuli. Real-time renal cell response can be recorded using this novel chamber, an inverted fluorescent microscope, and a computer. Ultimately, an understanding of how hypoxia and/or elevated pressure induce functional changes at the cellular level may provide insight into disease pathologies and lead to the development of novel drug and prevention therapies for renal failure.
Bioengineering Conference, 2004. Proceedings of the IEEE 30th Annual Northeast; 05/2004
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ABSTRACT: The highest need for engineers in the next decade will be in the biomedical sector. For this reason, the objective of the present study was to increase exposure and interest in biomedical engineering (BME) through a National Science Foundation (NSF) sponsored Research Experiences for Undergraduates (REU) program at Purdue University. To meet this goal, undergraduate students participating in the program (http://www.ecn.purdue.edu/BME/REU) conducted BME-related research on the Purdue campus during the summers of 2001-2003. Of these students, 82% were either females or underrepresented minorities and 70% had not had hands-on BME experiences at their undergraduate institution prior to the REU program. REU students attended weekly lab meetings, visited BME industries, made operating room/clinic trips, attended a bioethics series, prepared and presented 4'×6' research posters, and gave formal 30-minute long oral presentations to Purdue students/faculty/staff and visiting faculty. In addition, the research conducted over the summers by these outstanding students has resulted in 22 manuscripts and 33 abstracts that have been presented at national BME-related conferences, including three REU students who have been recognized with research awards. Finally, survey results provided evidence that REU participants were extremely pleased with the experience and were more likely to enroll in BME graduate programs at the conclusion of the REU program.
Bioengineering Conference, 2004. Proceedings of the IEEE 30th Annual Northeast; 05/2004
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ABSTRACT: Previous research has shown that increasing the nanometer surface roughness of poly(lactic-co-glycolic acid) (PLGA) films promotes vascular endothelial and smooth muscle cell adhesion. The goal of this in vitro research was to understand the mechanism(s) behind these observed responses. In order to elucidate the adhesive factors for vascular cell adhesion on nano-structured PLGA, substrates of various surface feature dimensions were exposed to serum-containing media overnight. The adsorbed proteins were then desorbed using a stripping buffer and the amount, as well as type, of proteins initially adsorbed were analyzed. Furthermore, cellular adhesion studies were preformed in order to correlate the link between specific protein adsorption and subsequent cellular response. Results showed that nano-structured PLGA adsorbed significantly more vitronectin and fibronectin when compared to conventional PLGA. Additionally, vascular cell adhesion studies demonstrated that both vascular smooth muscle cell and endothelial cell density increased on vitronectin and fibronectin pre-adsorbed onto nano-structured (compared to conventional) PLGA. In combination, these results provide insights into the mechanism(s) of increased vascular cell adhesion on nano-structured PLGA important for tissue engineering applications.
Bioengineering Conference, 2004. Proceedings of the IEEE 30th Annual Northeast; 05/2004
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ABSTRACT: Several kidney pathologies result in elevated pressures within the renal interstitial fluid, thereby affecting cell function. Traditionally, these and related studies have been performed on rigid substrates. The objective of the current study was, therefore, to better simulate in vivo conditions by performing cell studies on a variety of substrates including fibronectin, gelatin, tissue culture plasticware, glass, and PLGA. In vitro studies on these substrates were performed with tubular and medullary renal cells. Specifically, changes in cell number and microfilament arrangement were examined following exposure to pathological (180 and 300 cmH<sub>2</sub>O) pressures for 24 hours. Cell number studies provided evidence that exposure to pressures of 180 and 300 cmH<sub>2</sub>O resulted in increased tubular renal cell numbers. In contrast, pressure-exposed medullary cell numbers were decreased in response to 180 and 300 cmH<sub>2</sub>O. In both cell lines this response was more drastic in response to 300 cmH<sub>2</sub>O pressure. In addition, substrate-dependent changes in microfilament structures took place in pressure-exposed renal cells. In combination, these results prove that the function of renal cells was affected by both substrate and pressure exposure. Hopefully, elucidating such renal cell responses to pressure will aid in the design of novel, targeted drug therapies for treating kidney pathologies.
Bioengineering Conference, 2004. Proceedings of the IEEE 30th Annual Northeast; 05/2004
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ABSTRACT: It is of the utmost importance to increase the activity of bone cells on the surface of materials used in the design of orthopaedic implants. Increased activity of such cells can promote either integration of these materials into surrounding bone or complete replacement with naturally produced bone if biodegradable materials are used. Osteoblasts are bone-producing cells and, for that reason, are the cells of interest in initial studies of new orthopaedic implants. If these cells are functioning normally, they lay down bone matrix onto both existing bone and prosthetic materials implanted into the body. It is generally accepted that a successful material should enhance osteoblast function, leading to more bone deposition and, consequently, increased strength of the interface between the material and juxtaposed bone. The present study provided the first evidence of greater osteoblast function on carbon and alumina formulations that mimic the nano-dimensional crystal geometry of hydroxyapatite found in bone.
Medical & Biological Engineering & Computing 06/2003; 41(3):372-5. · 1.88 Impact Factor
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ABSTRACT: Polymers currently utilized for tissue engineering applications do not possess surfaces with nanostructured features. However, the tissue that the polymers will replace is composed of proteins that have nanometer dimensions. Undoubtedly, in situ, cells are accustomed to interacting with surface roughness values in the nanometer regime due to the presence of such proteins in natural tissue. Therefore, the objective of this paper was to design, synthesize and evaluate (using in vitro cellular models) poly-lactic-co-glycolic acid (PLGA) with nanostructured surface features to serve as the next generation of more efficient tissue engineered materials. For this purpose, nanostructured PLGA was created by treating conventional PLGA with various concentrations of NaOH for select periods of time. To eliminate surface chemistry changes created though the etching process, PLGA was cast from silastic molds of NaOH-treated nanostructured PLGA. Results provided the first evidence of increased numbers of vascular cells (specifically, endothelial and aortic smooth muscle cells) and bladder smooth muscle cells on nanostructured compared with conventional PLGA substrates. For this reason, the present results suggest, for the first time, that PLGA should incorporate a high degree of nanostructured surface roughness to enhance tissue regeneration for vascular and bladder applications.
IEEE Transactions on NanoBioscience 07/2002; · 1.28 Impact Factor
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ABSTRACT: Polymers currently utilized for tissue engineering applications do not possess surfaces with nanostructured features. In contrast, the tissue that the polymers will regenerate is composed of proteins that have nanometer dimensions. Undoubtedly, the presence of proteins in natural tissue provide for surface roughness values in the nanometer regime. For this reason, the objective of the present study was to design, synthesize, and evaluate (using in vitro cellular models) the ability of poly-lactic-co-glycolic acid (PLGA) as the next generation of more efficient tissue engineering materials. Results provided the first evidence that osteoblasts (bone-forming cells), chondrocytes (cartilage synthesizing cells), aortic smooth muscle cells, and bladder smooth muscle cells adhered and proliferated more on nanostructured compared to conventional PLGA substrates. For this reason, the present results suggest that to enhance tissue regeneration, PLGA should incorporate a high degree of nanostructured surface features.
Molecular, Cellular and Tissue Engineering, 2002. Proceedings of the IEEE-EMBS Special Topic Conference on; 02/2002
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ABSTRACT: Polymers currently utilized for tissue engineering applications do not possess surfaces with nano-structured features. In contrast, the tissue that the polymers will regenerate is composed of proteins that have nanometer dimensions. Undoubtedly, the presence of proteins in natural tissue provide for surface roughness values in the nanometer regime. For this reason, the objective of the present study was to design, synthesize, and evaluate (using in vitro cellular models) poly-lactic-co-glycolic acid (PLGA) for use as the next generation of more efficient tissue engineered materials. Results provided the first evidence that osteoblasts (bone-forming cells), chondrocytes (cartilage synthesizing cells), aortic smooth muscle cells, and bladder smooth muscle cells adhered and proliferated more on nanostructured compared to conventionally structured PLGA substrates. For this reason, the present results suggest that to enhance tissue regeneration, PLGA should incorporate a high degree of nano-structured surface features.
Engineering in Medicine and Biology, 2002. 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society EMBS/BMES Conference, 2002. Proceedings of the Second Joint; 02/2002
