Art
Matter Journal Cover
Michael Rosnach, Yichong Wang
SEM imaging of nanofibers
Biomimetic hierarchical fibrous hydrogels with high alignment and flaw insensitivity
Hang Yang, Yichong Wang, Yongjun Jang, Kevin Shani, Quan Jiao, Michael Peters, Kevin Kit Parker, Joost J. Vlassak
Natural structural materials often feature intricate hierarchical architectures across various scales, from nanometers to hundreds of microns, resulting in exceptional strength, toughness, and flaw insensitivity. However, achieving similar microstructures in engineering materials remains a formidable challenge. In this study, we combine the wet rotary jet spinning (WRJS) system with a salting-out process to fabricate highly anisotropic fibrous poly(vinyl alcohol) (PVA) hydrogels with controlled crystallinity and interfacial adhesion between fibers. We engineered hydrogels to emulate the mechanical characteristics of structural materials in nature. The resulting materials demonstrate excellent anisotropic alignment at both the molecular and fiber scales. By controlling adhesion between fibers, we obtain a compact material that is more ductile than both of the individual fibers of which it is composed and isotropic bulk PVA. Overall, these fibrous hydrogels exhibit mechanical properties comparable to various natural tissues, offering significant potential for applications in soft devices and tissue engineering.
APL Bioengineering Journal Cover
Michael Rosnach
Digital Painting
Self-organizing behaviors of cardiovascular
cells on synthetic nanofiber scaffolds
Michael M. Peters, Jackson K. Brister, Edward M. Tang, Felita W. Zhang, Veronica M. Lucian, Paul D. Trackey, Zachary Bone, John F. Zimmerman, Qianru Jin, F. John Burpo, and Kevin Kit Parker
In tissues and organs, the extracellular matrix (ECM) helps maintain inter- and intracellular architectures that sustain the structure–function relationships defining physiological homeostasis. Combining fiber scaffolds and cells to form engineered tissues is a means of replicating these relationships. Engineered tissues’ fiber scaffolds are designed to mimic the topology and chemical composition of the ECM network. Here, we asked how cells found in the heart compare in their propensity to align their cytoskeleton and self-organize in response to topological cues in fibrous scaffolds. We studied cardiomyocytes, valvular interstitial cells, and vascular endothelial cells as they adapted their inter and intracellular architectures to the extracellular space. We used focused rotary jet spinning to manufacture aligned fibrous scaffolds to mimic the length scale and three-dimensional (3D) nature of the native ECM in the muscular, valvular, and vascular tissues of the heart. The representative cardiovascular cell types were seeded onto fiber scaffolds and infiltrated the fibrous network. We measured different cell types’ propensity for cytoskeletal alignment in response to fiber scaffolds with differing levels of anisotropy. The results indicated that valvular interstitial cells on moderately anisotropic substrates have a higher propensity for cytoskeletal alignment than cardiomyocytes and vascular endothelial cells. However, all cell types displayed similar levels of alignment on more extreme (isotropic and highly anisotropic) fiber scaffold organizations. These data suggest that in the hierarchy of signals that dictate the spatiotemporal organization of a tissue, geometric cues within the ECM and cellular networks may homogenize behaviors across cell populations and demographics.
Matter Journal Cover
Michael Rosnach, Michael Peters
Photographed FRJS-spun nanofibers
On-demand heart valve manufacturing using
focused rotary jet spinning
Sarah E. Motta, Michael M. Peters, Christophe O. Chantre, Huibin Chang, Luca Cera, Qihan Liu, Elizabeth M. Cordoves, Emanuela S. Fioretta, Polina Zaytseva, Nikola Cesarovic, Maximilian Y. Emmert, Simon P. Hoerstrup, and Kevin Kit Parker
Pediatric heart valve disease affects children worldwide and necessitates valve replacements that remodel and grow with the patient. Current valve manufacturing technologies struggle to create valves that facilitate native tissue remodeling for permanent replacements. Here, we present focused rotary jet spinning (FRJS) for implantable medical devices, such as heart valves, to address this challenge. Combining RJS and a focused air stream, FRJS prints FibraValves, micro- and nanofibrous heart valves, in minutes. The micro- and nanoscale features provide structural cues to orient cells at the biotic-abiotic interface, while the centimeter-scale valve shape regulates cardiac flow. We built valves using poly(L-lactideco-Ɛ-caprolactone) fiber scaffolds, which supported rapid cellular infiltration and displayed native valve-like mechanical properties. Evaluating clinical translatability, we assessed acute performance in a large animal model using a transcatheter delivery approach. These tests indicate that FRJS is a viable method for manufacturing heart valves and future medical implants.
Biophysics Reviews Volume 3, Issue 2, 2022 Journal Cover
Michael Rosnach
Digital Painting
Recent drug discovery success signals renaissance in biophysics
Patrick R. Connelly
With a scope that spans the hierarchy of biological organization from molecules and cells to organisms and populations, the discipline of biophysics has been proven to be particularly well suited for connecting the molecular embodiments of human diseases to the medical conditions experienced by patients. Recently, fundamental biophysical research on aberrant proteins involved in maintaining salt and water balance in our lungs, oxygen transport from our lungs to the rest of the body, and the pumping of blood by our hearts have been successfully translated to the creation of transformational new medicines that are radically changing the lives of patients. With these and other emerging discoveries, the field of applied biophysics is experiencing the beginnings of a veritable renaissance era.
Translational Medicine 14 October 2020 Journal Cover
Michael Rosnach
Digital Sculpting
Endothelial extracellular vesicles contain protective proteins and rescue ischemia-reperfusion injury in a human heart-on-chip
Moran Yadid, Johan U. Lind, Herdeline Ann M. Ardoña, Sean P. Sheehy, Lauren E. Dickinson, Feyisayo Eweje, Maartje M.C. Bastings, Benjamin Pope, Blakely B. O’Connor, Juerg R. Straubhaar, Bogdan Budnik, Andre G. Kleber, Kevin Kit Parker
Extracellular vesicles (EVs) derived from various stem cell sources induce cardioprotective effects during ischemia-reperfusion injury (IRI). These have been attributed mainly to the antiapoptotic, proangiogenic, microRNA (miRNA) cargo within the stem cell–derived EVs. However, the mechanisms of EV-mediated endothelial signaling to cardiomyocytes, as well as their therapeutic potential toward ischemic myocardial injury, are not clear. EV content beyond miRNA that may contribute to cardioprotection has not been fully illuminated. This study characterized the protein cargo of human vascular endothelial EVs (EEVs) to identify lead cardioactive proteins and assessed the effect of EEVs on human laminar cardiac tissues (hlCTs) exposed to IRI. We mapped the protein content of human vascular EEVs and identified proteins that were previously associated with cellular metabolism, redox state, and calcium handling, among other processes. Analysis of the protein landscape of human cardiomyocytes revealed corresponding modifications induced by EEV treatment. To assess their human-specific cardioprotection in vitro, we developed a human heart-on-a-chip IRI assay using human stem cell–derived, engineered cardiac tissues. We found that EEVs alleviated cardiac cell death as well as the loss in contractile capacity during and after simulated IRI in an uptake- and dose-dependent manner. Moreover, we found that EEVs increased the respiratory capacity of normoxic cardiomyocytes. These results suggest that vascular EEVs rescue hlCTs exposed to IRI possibly by supplementing injured myocytes with cargo that supports multiple metabolic and salvage pathways and therefore may serve as a multitargeted therapy for IRI.
Matter Journal Cover
Michael Rosnach
Digital Painting
para-Aramid Fiber Sheets for Simultaneous
Mechanical and Thermal Protection in Extreme
Environments
Grant M. Gonzalez, Janet Ward, John Song, Kathleen Swana, Stephen A. Fossey, Jesse L. Palmer, Felita W. Zhang, Veronica M. Lucian, Luca Cera, John F. Zimmerman, F. John Burpo, and Kevin Kit Parker
Personnel operating in extreme environments require equipment that protects against multiple hazards. Currently, protection against both thermal and ballistic threats requires the combination of multiple high-performance materials that increases equipment weight and complexity. Here,wehypothesizedwecouldachieve simultaneous protection by manufacturing a porous network of aligned fibers, combiningthemechanical properties of continuousfibers with the thermal properties of porous aerogels. Choosing para-aramid polymers as the building block, we engineered precursor solutions to be fluid-like during fiber spinning and solid-like during fiber formation. This allowed for the fabrication of porous, continuous para-aramid fiber sheets (pAFS) with fiber diameters an order of magnitude lower than that of commercial para-aramid fibers. Although exhibiting moderately reduced single-fiber mechanics, these pAFS had fragment projectile resistance comparable with commercial para-aramids, while providing 20-fols heat-insulation capability. With these synergistic properties, the nanofiber sheets act as a multifunctional material that can provide improved simultaneous protection.
Nano Letters May 2019 Volume 19, Number 5 Journal Cover
Michael Rosnach
Digital Sculpting
Scatter Enhanced Phase Contrast Microscopy for Discriminating Mechanisms of Active Nanoparticle Transport in Living Cells
John F. Zimmerman, Herdeline Ann M. Ardoña, Georgios Pyrgiotakis, Jiaqi Dong, Brij Moudgil, Philip Demokritou, Kevin Kit Parker
Understanding the uptake and transport dynamics of engineered nanomaterials (ENMs) by mammalian cells is an important step in designing next-generation drug delivery systems. However, to track these materials and their cellular interactions, current studies often depend on surface-bound fluorescent labels, which have the potential to alter native cellular recognition events. As a result, there is still a need to develop methods capable of monitoring ENM-cell interactions independent of surface modification. Addressing these concerns, here we show how scatter enhanced phase contrast (SEPC) microscopy can be extended to work as a generalized label-free approach for monitoring nanoparticle uptake and transport dynamics. To determine which materials can be studied using SEPC, we turn to Lorenz–Mie theory, which predicts that individual particles down to ∼35 nm can be observed. We confirm this experimentally, demonstrating that SEPC works for a variety of metal and metal oxides, including Au, Ag, TiO2, CeO2, Al2O3, and Fe2O3 nanoparticles. We then demonstrate that SEPC microscopy can be used in a quantitative, time-dependent fashion to discriminate between distinct modes of active cellular transport, including intracellular transport and membrane-assisted transport. Finally, we combine this technique with microcontact printing to normalize transport dynamics across multiple cells, allowing for a careful study of ensemble TiO2 nanoparticle uptake. This revealed three distinct regions of particle transport across the cell, indicating that membrane dynamics play an important role in regulating particle flow. By avoiding fluorescent labels, SEPC allows for a rational exploration of the surface properties of nanomaterials in their native state and their role in endocytosis and cellular transport.
Extreme Mechanics Letters 25 (2018) Journal Cover
Michael Rosnach
CAD Modeing
A viscoelastic beam theory of polymer jets with application to rotary jet spinning
Qihan Liu, Kevin Kit Parker
Complex deformation of a polymer jet appears in many manufacturing processes, such as 3D printing, electrospinning, blow spinning, and rotary jet spinning. In these applications, a polymer melt or solution is first extruded through an orifice and forms a jet. The polymer jet is then dynamically deformed until the polymer solidifies. The final product is strongly affected by the deformation of the polymer jet. And the deformation is strongly affected by the viscoelasticity of the polymer. Here we develop a beam theory to incorporate both the nonlinear viscoelasticity and the bending/twisting stiffness of a polymer jet. As a demonstration, we study the formation of a polymer fiber under strong centrifugal force, a fiber manufacturing process known as rotary jet spinning.
Nature Biomedical Engineering 23 July 2018 Journal Cover
Michael Rosnach
Digital Sculpting
A tissue-engineered scale model of the heart ventricle
Luke A. MacQueen, Sean P. Sheehy, Christophe O. Chantre, John F. Zimmerman, Francesco S. Pasqualini, Xujie Liu, Josue A. Goss, Patrick H. Campbell, Grant M. Gonzalez, Sung-Jin Park, Andrew K. Capulli, John P. Ferrier, T. Fettah Kosar, L. Mahadevan, William T. Pu & Kevin Kit Parker
Laboratory studies of the heart use cell and tissue cultures to dissect heart function yet rely on animal models to measure pressure and volume dynamics. Here, we report tissue-engineered scale models of the human left ventricle, made of nanofibrous scaffolds that promote native-like anisotropic myocardial tissue genesis and chamber-level contractile function. Incorporating neonatal rat ventricular myocytes or cardiomyocytes derived from human induced pluripotent stem cells, the tissue-engineered ventricles have a diastolic chamber volume of ~500 µl (comparable to that of the native rat ventricle and approximately 1/250 the size of the human ventricle), and ejection fractions and contractile work 50–250 times smaller and 104–108 times smaller than the corresponding values for rodent and human ventricles, respectively. We also measured tissue coverage and alignment, calcium-transient propagation and pressure–volume loops in the presence or absence of test compounds. Moreover, we describe an instrumented bioreactor with ventricular-assist capabilities, and provide a proof-of-concept disease model of structural arrhythmia. The model ventricles can be evaluated with the same assays used in animal models and in clinical settings.
Nature Biotechnology Volume 36 Number 6 June 2018 Journal Cover
Michael Rosnach
Digital Sculpting
Photosynthetic artificial organelles sustain and control ATP-dependent reactions in a protocellular system
Keel Yong Lee, Sung-Jin Park, Keon Ah Lee, Se-Hwan Kim, Heeyeon Kim, Yasmine Meroz,
L Mahadevan, Kwang-Hwan Jung, Tae Kyu Ahn, Kevin Kit Parker & Kwanwoo Shin
Inside cells, complex metabolic reactions are distributed across the modular compartments of organelles1,2. Reactions in organelles have been recapitulated in vitro by reconstituting functional protein machineries into membrane systems3–5. However, maintaining and controlling these reactions is challenging. Here we designed, built, and tested a switchable, light-harvesting organelle that provides both a sustainable energy source and a means of directing intravesicular reactions. An ATP (ATP) synthase and two photoconverters (plant-derived photosystem II and bacteriaderived proteorhodopsin) enable ATP synthesis. Independent optical activation of the two photoconverters allows dynamic control of ATP synthesis: red light facilitates and green light impedes ATP synthesis. We encapsulated the photosynthetic organelles in a giant vesicle to form a protocellular system and demonstrated optical control of two ATP-dependent reactions, carbon fixation and actin polymerization, with the latter altering outer vesicle morphology. Switchable photosynthetic organelles may enable the development of biomimetic vesicle systems with regulatory networks that exhibit homeostasis and complex cellular behaviors.
Macromolecular Materials and Engineering Journal Cover
Michael Rosnach
Digital Painting
Production of Synthetic, Para-Aramid
and Biopolymer Nanofibers by Immersion
Rotary Jet-Spinning
Grant M. Gonzalez, Luke A. MacQueen, Johan U. Lind, Stacey A. Fitzgibbons, Christophe O. Chantre, Isabelle Huggler, Holly M. Golecki, Josue A. Goss, Kevin Kit Parker
Nanofiber production platforms commonly rely on volatile carrier solvents or high voltages. Production of nanofibers comprised of charged polymers or polymers requiring nonvolatile solvents thus typically requires customization of spinning setup and polymer dope. In severe cases, these challenges can hinder fiber formation entirely. Here, a versatile system is presented which addresses these challenges by employing centrifugal force to extrude polymer dope jet through an air gap, into a flowing precipitation bath. This voltage-free approach ensures that nanofiber solidification occurs in liquid, minimizing surface tension instability that results in jet breakup and fiber defects. In addition, nanofibers of controlled size and morphology can be fabricated by tuning spinning parameters including air gap length, spinning speed, polymer concentration, and bath composition. To demonstrate the versatility of our platform, para-aramid (e.g., Kevlar) and biopolymer (e.g., DNA, alginate) nanofibers are produced that cannot be readily produced using standard nanofiber production methods.
Vanderbilt Fall 2016 Journal Cover
Michael Rosnach
Digital Painting
Science 8 July 2016 Journal Cover
Science Journal Photography
Phototactic guidance of a tissue-engineered soft-robotic ray
Sung-Jin Park, Mattia Gazzola, Kyung Soo Park, Shirley Park, Valentina Di Santo, Erin L. Blevins, Johan U. Lind, Patrick H. Campbell, Stephanie Dauth, Andrew K. Capulli, Francesco S. Pasqualini, Seungkuk Ahn, Alexander Cho, Hongyan Yuan, Ben M. Maoz, Ragu Vijaykumar, Jeong-Woo Choi, Karl Deisseroth, George V. Lauder, L. Mahadevan, Kevin Kit Parker
Inspired by the relatively simple morphological blueprint provided by batoid fish such as stingrays and skates, we created a biohybrid system that enables an artificial animal—a tissue-engineered ray—to swim and phototactically follow a light cue. By patterning dissociated rat cardiomyocytes on an elastomeric body enclosing a microfabricated gold skeleton, we replicated fish morphology at 1=10 scale and captured basic fin deflection patterns of batoid fish. Optogenetics allows for phototactic guidance, steering, and turning maneuvers. Optical stimulation induced sequential muscle activation via serpentinepatterned muscle circuits, leading to coordinated undulatory swimming. The speed and direction of the ray was controlled by modulating light frequency and by independently eliciting right and left fins, allowing the biohybrid machine to maneuver through an obstacle course.