Summer 2010 Research Projects
Bean and Flowers
Next Generation Spermicides
Barry Bean, Ph.D., Biological Sciences
Robert Flowers, Ph.D., Chemistry
The commonly used spermicide nonoxynol-9 gives partial protection against pregnancy, but causes vaginal irritation and increases the likelihood for transmission of some STDs. The architecture of human sperm cells includes several distinctive membrane regions that undergo substantial changes during the life history of the sperm cell. Specific changes must take place within the compartments and membranous surfaces of sperm to enable fertilization. We have previously synthesized and tested several new compounds that may lead to improved spermicides. In preliminary studies, our fluorine-containing surfactants selectively inhibited human sperm cells. Based on those results, we will synthesize a family of additional fluorous compounds, and conduct experiments to identify compounds that give the greatest selectivity against human sperm, efficacy as contraceptives in animals, and acceptable profiles as antimicrobial agents.
Cheng and Gilchrist
Fabrication of Nanoporous Membranes for
Xuanhong Cheng, Ph.D., Bioengineering
James Gilchrist, Ph.D., Chemical Engineering
Nanoporous membrane materials are one of the key components in many biomedical applications including bioseparation, controlled release, tissue engineering and biosensing. The goal of the current research program is to develop a new fabrication process for thin-film, polymer nanoporous membranes that can be utilized for bio-nano-particle enrichment. Not only will the membranes have superior physical properties, including uniform and controllable pore sizes, high porosity, ordered pore arrangement, flexibility and mechanical strength, they are also expected to possess versatile chemistry for biomolecular immobilization and resistance to fouling. Specifically, the membrane will be fabricated by templating colloidal crystal substrates. Such substrates are created through convective deposition of uniform-size silica nano- or micro-beads to form highly ordered crystalline monolayers. The membrane will then be packaged in microfluidic chips and explored for nanoparticle purification and concentration, which in the long term, will lead to the PIs’ research interest in creating a whole particle viral detector.
Coulter and Jedlicka
Mesenchymal stem cells and mechanotransduction
John Coulter, Ph.D., Mechanical Engineering and Mechanics
Sabrina Jedlicka, Ph.D., Computer Sciences & Engineering
The overall aim of this summer research program is to investigate manufacturable cell growth substrata with mechanically tunable nanostructured features, resulting in a new generation of petri dishes optimally designed for maintenance and differentiation of variable cell phenotypes. Traditional approaches to in vitro cell culture has seen many advancements, including media formulations, protein substrates, and genetic engineering. However, these approaches are limited by a common substrate – the petri dish.
The structure and function of mammalian cells and tissues are regulated not only by the biochemical properties, but also by the structure and mechanical compliance of the substrate on which the cells are placed. A great deal of research has focused on this idea in the past 10 years, with many new wet bench and synthetic developments demonstrating the feasibility of mechanically and chemically directed cell differentiation. However, these studies lack wide-scale manufacturability.
An investigation of manufacturable mechanically tunable substrata has the potential to significantly enhance biomedical capabilities in cell biology. The recent emergence of nanoscale injection molding has created a situation in which optimized bio-relevant mechanical surface characteristics can be realized. The proposed project would target this opportunity with the goal of creating an alternative to traditional petri dishes, by examining the following:
- To investigate the capability to fabricate nanoscale surface features with controlled mechanical response that can be injection molded using target biocompatible polymers.
- To examine the potential of hMSC adhesion and differentiation on material substrates of interest. This will be coupled with examination of the resultant mechanical response of the polymer structure in response to cell adhesion.
These experiments coupled will allow for in depth correlation between cell function and material properties in future work.
Falk and Jain
Biocompatibility of nano-macro dual-porous
glass bone-replacement scaffolds
Matthias Falk, Ph.D., Biological Sciences
Himanshu Jain, Ph.D., Materials Science
One of the key challenges in today’s medicine is the treatment of organ failure or tissue loss. Advances in cell biology and material sciences have led to tissue engineering where healthy progenitor cells are delivered to the injured site on biocompatible scaffolds to regenerate lost or damaged tissue. This approach has delivered particularly successful results for bone replacement using bone-scaffolds made from CaO-P2O5-SiO2 based glass ceramics. Millions of patients have benefited from implants made from such bioactive glasses.
A macro porous structure of the glass scaffolds is necessary to obtain good implant incorporation through rapid vascularization and bone ingrowth, since such porosity promotes cell growth on the surface as well inside the scaffolds. For additional benefits, the scaffolds should consist of nanopores, which simulate the natural extracellular environment. We have developed two novel methods for fabricating such bioactive glasses based on: (a) conventional melt-quench method followed by selective heating and etching, and (b) a sol-gel procedure with polymerization induced phase separation. In recent months, we have further improvised scaffold fabrication techniques by using nano porous powders prepared by these two methods. The new methods introduce larger macro pores and much greater overall porosity required for bone scaffolds.
In this BDSI Research Project we will fabricate the dual-porous glass bone-replacement scaffolds using the improvised procedures. Next, building on previous experience, the team will commence testing their biocompatibility and bioactivity,by monitoring the colonization and growth of MC3T3 bone-precursor cells. Nano-macro dual porosity glasses with different chemical composition, pore-characteristics, and bioactive coatings will be tested for cell attachment, migration, proliferation, and differentiation. We will also investigate potential detrimental impact of the products of leaching from glass. Appropriate fluorescence-based cell detection methods have been established. Thus, this Summer Institute, in combination with our ongoing work supported by NSF and IMI-NFG will help optimize scaffold fabrication and performance. It will provide the basis for further testing of our glass scaffolds in vivo by our partners at Tissue Engineering Laboratory, Faculty of Dentistry, Alexandria University, Egypt.
Huang and Vavylonis
Analysis of actin cytoskeleton structures
using active contours
Xiaolei Huang, Ph.D., Computer Science & Engineering
Dimitrios Vavylonis, Ph.D., Physics
Actin is one of the most abundant proteins in cells. It has the ability to polymerize into long filaments out of monomers (single proteins). These filaments form a fibrous network within cells called the "cytoskeleton". The cytoskeleton provides cells with mechanical integrity and shape. Through the fast assembly and disassembly of the the cytoskeleton fibers, cells can change shape, move and divide.
Our team focuses on quantitative analysis and modeling of cytoskeletal organization in vitro and in living cells. Our work is based on images of fluorescently labeled actin filaments provided to us by experimental collaborators. We have recently developed software which extracts and tracks growing actin filaments on a glass slide (two dimensions). Our summer 2010 BDSI project focuses on developing computational methods and software for analysis of actin cytoskeleton networks in three dimensional images obtained by confocal microscopy.
We will further generalize methods of describing individual filaments to describe networks of filaments. The improved software will be used
to systematically analyze actin cables in live yeast cells. In particular, we will quantify bending and torsional statistics of actin bundles which relate to the mechanical properties of actin filaments. In this way, we aim to obtain results that provide insight into the mechanisms of actin assembly and the mechanical forces involved.
Heindel, Lu and Garippa
New drugs for
Ned Heindel, Ph.D., Chemistry
Shifang Lu, Ph.D., Biological Sciences
Carrie Garippa, Biological Sciences
Chronic stress is a significant contributing factor in central nervous system disorders, including depression and post-traumatic stress disorder. These conditions are a major public health problem and carry an annual economic burden in excess of $125 billion. Available drugs for major depression, which are primarily monoamine reuptake inhibitors, are ineffective in 50% of patients. Current drug therapies for PTSD are repurposed antidepressants and anti-anxiety drugs that are only modestly effective, produce undesirable side effects, and offer limited relief. These findings indicate that a new approach to treatment can potentially improve clinical outcomes. Elevated vasopressin expression in the brain has been observed in depressed humans, in veterans with PTSD and in rodent models of depression and anxiety. In this project, we will characterize vasopressin function in preclinical models of stress-related disorders and test the ability of vasopressin antagonists as an intervention strategy to prevent the adverse effects of chronic stress on brain function and behavior.
Tatic-Lucic and Perry
Development of a reliable method for
measuring electrical properties of biological cells
Svetlana Tatic-Lucic, Ph.D., Electrical & Computer Engineering
Susan Perry, Ph.D., Bioengineering
Precise positioning of cells is a necessary component for successful utilization of certain classes of BioMEMS (micro-electro-mechanical system) devices. In our lab, we use dielectrophoresis (DEP) to trap cells in desired positions within BioMEMS. Our work has shown that different ranges of parameters are specific for sucessful trapping of different types of cells. However, these parameters are not often obvious, and conditions for cell capture must be empirically determined. It has been suggested, however, that the dielectric properties of individual cell types can be used to anticipate the parameters necessary for successful cell trapping by dielectrophoresis.
The focus of our project, therefore, will be to continue our efforts to implement an experimental setup, designed by 2009 BDSI students, for measuring the dielectric properties of mammalian cells. The information obtained will be used to model the optimal range of parameters to be used for cell trapping by dielectrophoresis for use in a BioMEMS device, and will aid in the successful design of DEP electrodes.
Our interdisciplinary project is a collaborative effort between Svetlana Tatic-Lucic (Electrical and Computer Engineering and Bioengineering) and Susan Perry (Bioengineering)