Institute for Medicine and Engineering

The mission of the Institute for Medicine and Engineering (IME) is to stimulate fundamental research at the interface between biomedicine and engineering/physical/computational sciences leading to innovative applications in biomedical research and clinical practice. The IME was created in 1996 by the Schools of Medicine (SOM) and Engineering and Applied Science (SEAS) to pursue opportunities for collaborative research. The IME has been successful in obtaining over $80 million in extramural grants, and funded programs. These include a research center in Cell Studies of Pulmonary Artery Hypertension, and a Penn Center for Molecular Discovery.

Membership: The Institute houses 11 core faculty, 6 from the School of Medicine and 5 from SEAS, who were recruited to form the basis for the IME; however, the Institute extends beyond the core group to include 106 members from various schools including School of Medicine, SEAS and Arts and Sciences faculty. The Institute interacts with 24 other Centers or departments.

Multi-disciplinary Research: The IME mission to foster research at the interface of medicine and engineering is met (i) through 8 central investigators who span these disciplines in both schools, (ii) through the core facilities, pilot grant programs, research training, and educational events involving its very wide membership (of 106). The research conducted by central investigators is quite broad, ranging from cell and molecular biology to tissue engineering, biophysics and nanobiology/medicine. Having established a strong basic research foundation the Institute is now expanding translational programs in medicine and engineering.

Strategic Importance: The IME relates directly to 3 major themes of the SOM Research Strategic Plan: Cancer, Neurosciences and Cardiovascular Biology. The University Strategic Plan identifies the link between engineering and medicine as one of the key drivers of success and recommends "fostering advances in engineering, computing, chemistry, mathematics and behavioral sciences that can be applied to life sciences." Because of the multi-disciplinary nature of the Institute, it is well positioned to take advantage of the new NIH roadmap. Because of its unique interface with SEAS, the IME is a strong force in faculty retention by providing unique directions and connections for research among faculty.





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Now showing 1 - 6 of 6
  • Publication
    Elongation and Fluctuations of Semi-flexible Polymers in a Nematic Solvent
    (2004-03-26) Dogic, Z.; Discher, Dennis E; Janmey, Paul; Kamien, Randall; Lubensky, Thomas C.; Discher, Dennis E; Janmey, Paul; Kamien, Randall; Lubensky, Thomas C.; Yodh, Arjun
    We directly visualize single polymers with persistence lengths ranging from lp = 0:05 to 16 µm, dissolved in the nematic phase of rod-like fd virus. Polymers with sufficiently large persistence length undergo a coil-rod transition at the isotropic-nematic transition of the background solvent. We quantitatively analyze the transverse fluctuations of semi-flexible polymers and show that at long wavelengths they are driven by the fluctuating nematic background. We extract both the Odijk deflection length and the elastic constant of the background nematic phase from the data.
  • Publication
    Electrostatic Repulsion of Positively Charged Vesicles and Negatively Charged Objects
    (1999-07-16) Aranda-Espinoza, Helim; Lubensky, Thomas C.; Nelson, Philip; Lubensky, Thomas C.; Nelson, Philip; Ramos, Laurence; Weitz, David A
    A positively charged, mixed bilayer vesicle in the presence of negatively charged surfaces (for example, colloidal particles) can spontaneously partition into an adhesion zone of definite area, and another zone that repels additional negative objects. Although the membrane itself has nonnegative charge in the repulsive zone, negative counterions on the interior of the vesicle spontaneously aggregate there, and present a net negative charge to the exterior. Beyond the fundamental result that oppositely charged objects can repel, our mechanism helps explain recent experiments on surfactant vesicles.
  • Publication
    Cholesterol Depletion Increases Membrane Stiffness of Aortic Endothelial Cells
    (2004-11-01) Byfield, Fitzroy H; Byfield, Fitzroy H; Aranda-Espinoza, Helim; Romanenko, Victor G.; Rothblat, George H.; Levitan, Irena
    This study has investigated the effect of cellular cholesterol on membrane deformability of bovine aortic endothelial cells. Cellular cholesterol content was depleted by exposing the cells to methyl-ß-cyclodextrin or enriched by exposing the cells to methyl-ß-cyclodextrin saturated with cholesterol. Control cells were treated with methyl-ß-cyclodextrincholesterol at a molar ratio that had no effect on the level of cellular cholesterol. Mechanical properties of the cells with different cholesterol contents were compared by measuring the degree of membrane deformation in response to a step in negative pressure applied to the membrane by a micropipette. The experiments were performed on substrate-attached cells that maintained normal morphology. The data were analyzed using a standard linear elastic half-space model to calculate Young elastic modulus. Our observations show that, in contrast to the known effect of cholesterol on membrane stiffness of lipid bilayers, cholesterol depletion of bovine aortic endothelial cells resulted in a significant decrease in membrane deformability and a corresponding increase in the value of the elastic coefficient of the membrane, indicating that cholesterol-depleted cells are stiffer than control cells. Repleting the cells with cholesterol reversed the effect. An increase in cellular cholesterol to a level higher than that of normal cells, however, had no effect on the elastic properties of bovine aortic endothelial cells. We also show that although cholesterol depletion had no apparent effect on the intensity of F-actin-specific fluorescence, disrupting F-actin with latrunculin A abrogated the stiffening effect. We suggest that cholesterol depletion increases the stiffness of the membrane by altering the properties of the submembrane F-actin and/or its attachment to the membrane.
  • Publication
    Domain unfolding in neurofilament sidearms: effects of phosphorylation and ATP
    (2002-10-10) Aranda-Espinoza, Helim; Janmey, Paul; Discher, Dennis E; Janmey, Paul; Discher, Dennis E
    Lateral projections of neuro¢laments (NF) called sidearms (SA) a¡ect axon stability and caliber. SA phosphorylation is thought to modulate inter-NF distance and interactions between NF and other subcellular organelles. SA were probed by atomic force microscopy (AFM) and dynamic light scattering (DLS) as a function of phosphorylation and ATP content. DLS shows SA are larger when phosphorylated, and AFM shows four unfoldable domains in SA regardless of phosphorylation state or the presence of ATP. However, the native phosphorylated SA requires three-fold higher force to unfold by AFM than dephosphorylated SA, suggesting a less pliant as well as larger structure when phosphorylated.
  • Publication
    Pore Stability and Dynamics in Polymer Membranes
    (2003-11-15) Hammer, Daniel A; Discher, Dennis E; Hammer, Daniel A; Discher, Dennis E
    Vesicles self-assembled from amphiphilic diblock copolymers exhibit a wide diversity of behavior upon poration, due to competitions between edge, surface and bending energies, while viscous dissipation mechanisms determine the time scales. The copolymers are essentially chemically identical, only varying in chain length (related to the membrane thickness d). For small d, we find large unstable pores and the resulting membrane fragments reassemble into vesicles within minutes. For large d, however, submicron pores form and are extremely long-lived. The results show that pore behavior depends strongly on d, suggesting that the relevant energies depend on d and pore size r in a more complexmanner than what is generally assumed. Further control over these systems would make them useful for numerous applications.
  • Publication
    Electromechanical Limits of Polymersomes
    (2001-11-12) Aranda-Espinoza, Helim; Bermudez, Harry; Discher, Dennis E; Discher, Dennis E
    Self-assembled membranes of amphiphilic diblock copolymers enable comparisons of cohesiveness with lipid membranes over the range of hydrophobic thicknesses d = 3-15 nm. At zero mechanical tension the breakdown potential Vc for polymersomes with d = 15 nm is 9 V, compared to 1 V for liposomes with d = 3 nm. Nonetheless, electromechanical stresses at breakdown universally exhibit a V2 c dependence, and membrane capacitance shows the expected strong d dependence, conforming to simple thermodynamic models. The viscous nature of the diblock membranes is apparent in the protracted postporation dynamics.