Biophysical Society Thematic Meeting | Riga 2026

PROGRAM & ABSTRACTS

Biophysical Society Thematic Meetings

Active and Responsive Soft Matter: From Biological to Engineered Systems Riga, Latvia | July 20-24, 2026

Organizing Committee

Andrejs C ē bers, University of Latvia, Latvia Damien Faivre, University of Latvia, Latvia Guy Genin, Washington University in St. Louis, USA Paul Janmey, University of Pennsylvania, USA Guntars Kitenbergs, University of Latvia, Latvia

Alison Patteson, Syracuse University, USA Mara Šmite, University of Latvia, Latvia

Thank You to Our Sponsors

Thank you to all sponsors for their support.

Active and Responsive Soft Matter: From Biological to Engineered Systems

Welcome Letter

July 2026

Dear Colleagues,

We would like to welcome you to the Biophysical Society Thematic Meeting entitled, Active and Responsive Soft Matter: From Biological to Engineered Systems . This meeting will convene leading theoretical and experimental researchers to examine how physical stimuli influence active and responsive biological systems. The meeting will focus on the mechanisms by which cells sense and respond to their physical environment. Key themes include the behavior of eukaryotic and prokaryotic cells in two-dimensional sheets and three dimensional matrices; collective dynamics of biological swimmers and their responses to mechanical and magnetic cues; emerging tools and analytical methods in mechanobiology; and the multiscale emergence of tissue mechanics from cells, fibers, and adhesions. The meeting is designed to foster cross-disciplinary exchange between fundamental biophysics of living active matter and the development of synthetic active and responsive materials inspired by biological principles. Hosting the event in Latvia, and more broadly in the Baltic States, will strengthen regional scientific connections and showcase Latvia’s strong research presence in magnetic systems, microfluidics, lab-on-a-chip technologies, and other physics-based approaches to biology and biomedicine. Overall, this conference will feature 17 posters, 33 lectures, and bring together over 50 scientists from a wide range of backgrounds and expertise. We hope that this meeting will not only provide a place to share your recent findings, but also to help promote new collaborations, helpful discussions, and future connections. We invite you all to actively take part in the discussions following each talk, the poster sessions, and the informal exchanges that will be possible during the coffee breaks and meals. We also hope that you will also enjoy the beautiful city of Riga!

The Organizing Committee Andrej Cēbers Damien Favre Guy Genin Paul Janmey Gunters Kitenbergs Alison Patteson Mara Šmite

Active and Responsive Soft Matter: From Biological to Engineered Systems

Meeting Code of Conduct

Biophysical Society Code of Conduct, Anti-Harassment Policy The Biophysical Society (BPS) is committed to providing an environment that encourages the free expression and exchange of scientific ideas. As a global, professional Society, the BPS is committed to the philosophy of equal opportunity and respectful treatment for all, regardless of national or ethnic origin, religion or religious belief, gender, gender identity or expression, race, color, age, marital status, sexual orientation, disabilities, veteran status, or any other reason not related to scientific merit. All BPS meetings and BPS-sponsored activities promote an environment that is free of inappropriate behavior and harassment by or toward all attendees and participants of Society events, including speakers, organizers, students, guests, media, exhibitors, staff, vendors, and other suppliers. BPS expects anyone associated with an official BPS-sponsored event to respect the rules and policies of the Society, the venue, the hotels, and the city. Definition of Harassment The term “harassment” includes but is not limited to epithets, unwelcome slurs, jokes, or verbal, graphic or physical conduct relating to an individual’s race, color, religious creed, sex, national origin, ancestry, citizenship status, age, gender or sexual orientation that denigrate or show hostility or aversion toward an individual or group. Sexual harassment refers to unwelcome sexual advances, requests for sexual favors, and other verbal or physical conduct of a sexual nature. Behavior and language that are welcome/acceptable to one person may be unwelcome/offensive to another. Consequently, individuals must use discretion to ensure that their words and actions communicate respect for others. This is especially important for those in positions of authority since individuals with lower rank or status may be reluctant to express their objections or discomfort regarding unwelcome behavior. It does not refer to occasional compliments of a socially acceptable nature. It refers to behavior that is not welcome, is personally offensive, debilitates morale, and therefore, interferes with work effectiveness. The following are examples of behavior that, when unwelcome, may constitute sexual harassment: sexual flirtations, advances, or propositions; verbal comments or physical actions of a sexual nature; sexually degrading words used to describe an individual; a display of sexually suggestive objects or pictures; sexually explicit jokes; unnecessary touching. Attendees or participants who are asked to stop engaging in harassing behavior are expected to comply immediately. Anyone who feels harassed is encouraged to immediately inform the alleged harasser that the behavior is unwelcome. In many instances, the person is unaware that their conduct is offensive and when so advised can easily and willingly correct the conduct so that it does not reoccur. Anyone who feels harassed is NOT REQUIRED to address the person believed guilty of inappropriate treatment. If the informal discussion with the alleged harasser is unsuccessful in remedying the problem or if the complainant does not feel comfortable with such an approach, they can report the behavior as detailed below. Reported or suspected occurrences of harassment will be promptly and thoroughly investigated. Following an investigation, BPS will immediately take any necessary and appropriate action. BPS will not permit or condone any acts of retaliation against anyone who files harassment complaints or cooperates in the investigation of same. Reporting a Violation Violations of this Conduct Policy should be reported immediately. If you feel physically unsafe or believe a crime has been committed, you should report it to the police immediately. To report a violation to BPS:

• You may do so in person at the Annual Meeting at the BPS Business Office in the convention center.

Active and Responsive Soft Matter: From Biological to Engineered Systems

Meeting Code of Conduct

• You may do so in person to BPS senior staff at Thematic Meetings, BPS Conferences, or other BPS events.

• At any time (during or after an event), you can make a report through

http://biophysics.ethicspoint.com or via a dedicated hotline (phone numbers listed on the website) which will collect and relay information in a secure and sensitive manner.

Reported or suspected occurrences of harassment will be promptly and thoroughly investigated per the procedure detailed below. Following an investigation, BPS will immediately take any necessary and appropriate action. BPS will not permit or condone any acts of retaliation against anyone who files harassment complaints or cooperates in the investigation of same. Investigative Procedure All reports of harassment or sexual harassment will be treated seriously. However, absolute confidentiality cannot be promised nor can it be assured. BPS will conduct an investigation of any complaint of harassment or sexual harassment, which may require limited disclosure of pertinent information to certain parties, including the alleged harasser. Once a complaint of harassment or sexual harassment is received, BPS will begin a prompt and thorough investigation. Please note, if a complaint is filed anonymously, BPS may be severely limited in our ability to follow-up on the allegation. • An impartial investigative committee, consisting of the current President, President-Elect, and Executive Officer will be established. If any of these individuals were to be named in an allegation, they would be excluded from the committee. • The committee will interview the complainant and review the written complaint. If no written complaint exists, one will be requested. • The committee will speak to the alleged offender and present the complaint. • The alleged offender will be given the opportunity to address the complaint, with sufficient time to respond to the evidence and bring his/her own evidence. • If the facts are in dispute, the investigative team may need to interview anyone named as witnesses. • The investigative committee may seek BPS Counsel’s advice. • Once the investigation is complete, the committee will report their findings and make recommendations to the Society Officers. • If the severity of the allegation is high, is a possible repeat offense, or is determined to be beyond BPS’s capacity to assess claims and views on either side, BPS may refer the case to the alleged offender’s home institution (Office of Research Integrity of similar), employer, licensing board, or law enforcement for their investigation and decision. Disciplinary Actions Individuals engaging in behavior prohibited by this policy as well as those making allegations of harassment in bad faith will be subject to disciplinary action. Such actions range from a written warning to ejection from the meeting or activity in question without refund of registration fees, being banned from participating in future Society meetings or Society-sponsored activities, being expelled from membership in the Society, and reporting the behavior to their employer or calling the authorities. In the event that the individual is dissatisfied with the results of the investigation, they may appeal to the President of the Society. Any questions regarding this policy should be directed to the BPS Executive Officer or other Society Officer.

Active and Responsive Soft Matter: From Biological to Engineered Systems

Table of Contents

Table of Contents

General Information……………………………………………………………………………....1 Program Schedule..……………………………………………………………………………….3 Speaker Abstracts………………………………………………………………………………...8 Poster Sessions…………………………………………………………………………………...33

Active and Responsive Soft Matter: From Biological to Engineered Systems

General Information

GENERAL INFORMATION

Registration/Information Location and Hours The meeting will take place at the University of Latvia, House of Science, located at Jelgavas iela 3, Riga, LV-1004, Latvia. To pick up your badge and meeting materials, please visit the BPS Registration Desk, located on the 1 st Floor Lobby during the following times: Monday, July 20 13:30 – 17:00 Tuesday, July 21 8:30 – 17:00 Wednesday, July 22 8:30 – 13:00 Thursday, July 23 8:30 – 16:00 Friday, July 24 8:30 – 13:00 Instructions for Presentations (1) Presentation Facilities: A data projector will be available in the Gamma Conference Room, located on Level 1. Speakers are required to bring their own laptops and adaptors. It is recommended to have a backup of the presentation on a USB drive in case of any unforeseen circumstances. Speakers are advised to preview their final presentations before the start of each session. (2) Poster Session: 1) All poster sessions will be held in the Delta/Omega Room. 2) A display board measuring 90 cm by 179 cm (portrait orientation) will be provided for each poster. Poster boards are numbered according to the same numbering scheme as listed in the E-book. 3) Typeface should be large enough to be read comfortably by interested attendees from distances of 1.5 meters (4-5 feet). Authors are expected to bring their own pushpins, thumbtacks, or Velcro for mounting poster materials. 4) Posters can be set up on the morning of Tuesday, July 21 and can remain for the entirety of the meeting. There will be formal poster presentations on Thursday from 14:00 – 16:00. Please refer to the daily schedule for your formal presentation date and time. Two (2) hours have been allotted for poster presentations. Presenting authors with odd numbered poster boards should present during the first 60 minutes, and those with even numbered poster boards should present during the last 60 minutes. 5) During the assigned poster presentation sessions, presenters are requested to remain in front of their poster boards to meet with attendees. 6) All posters left uncollected at the end of the meeting will be discarded.

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Active and Responsive Soft Matter: From Biological to Engineered Systems

General Information

Note Pads/Pens Society pens will be provided, however please bring your own note pad. Meals, Coffee Breaks, and Socials

The opening mixer will be held on the 2 nd Floor Atrium. Coffee breaks and luncheons will be served in the Delta/Omega Room on Level 1. The Thursday evening banquet dinner will be held at 18:00 (6:00 PM) in the Terase I of the Gutenbergs Restaurant, located at Doma laukums 1, Centra rajons, Rīga, LV -1050, Latvia. Smoking Please be advised that the University of Latvia, House of Science is a non-smoking facility. Name Badges Name badges will be given to you when you check in at the Registration Desk on the 1 st Floor Lobby. Badges are required to enter all scientific sessions, poster sessions, and social functions. Please wear your badge throughout the conference. Internet Wi-Fi will be provided at the venue. Information will be available at the registration desk. On-Site Contact Information If you have any further requirements during the meeting, please contact the meeting staff at the registration desk from July 20–24 during registration hours. In case of emergency, you may contact the following: Dorothy Chaconas Phone: 301-785-0802 Email: dchaconas@biophysics.org Erica Bellavia Phone: 571-435-7669 Email: ebellavia@biophysics.org

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Daily Schedule

Active and Responsive Soft Matter: From Biological to Engineered Systems Riga, Latvia July 20-24, 2026 All scientific sessions will be held in Gamma Conference Room unless otherwise noted.

Monday, July 20, 2026

13:30 – 17:00

1 st Floor Lobby

Registration & Information

Session I

Keynote Talks Chair: Paul Janmey, University of Pennsylvania, USA Guntars Kitenbergs, University of Latvia, Latvia Welcome & Opening Remarks Patricia Bassereau, Institute Curie, France Dynamics of Cytoskeletal Filaments Inside Cellular Tethers Alexander Bershadsky, National University of Singapore, Singapore Integrin Adhesion Complexes Sensing Substrate Nano-Topography

15:00 – 15:10

15:10 – 16:05

16:05 – 17:00

17:00 – 19:00

Ice Breaker & Welcome Reception

2 nd Floor Atrium

Tuesday, July 21, 2026 8:30 – 17:00

1 st Floor Lobby

Registration & Information

Session II

Funding Chair: Damien Faivre, University of Latvia, Latvia

9:00 – 9:45

Manana Sukhareva, NIH/NIBIB, USA Next-Generation Biomedical Engineering: Opportunities and Challenges Janne Salo, European Research Council, Belgium European Research Council: Funding for Frontier Research

9:45 – 10:30

10:30 – 11:00

Coffee Break

Delta/Omega Room

Session III

Membrane and Interphases Chair: Guy Genin, Washington University in St. Louis, USA Alison Patteson, Syracuse University, USA Unraveling the Role of Vimentin in Cell Migration

11:00 – 11:30

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Daily Schedule

11:30 – 12:00

Kandice Levental, University of Virginia, USA Actively Driven Lipid Asymmetry Creates Unique Plasma Membrane Properties

12:00 – 13:00

Lunch

Delta/Omega Room

Session IV

Soft Matter Biophysics Chair: Guy Genin, Washington University in St. Louis, USA

13:00 – 13:30

Fred C. MacKintosh, Rice University, USA Mechanical Phase Transitions and the Nonlinear Response of Biopolymer Matrices Treena Arinzeh, Columbia University, USA Directing Regeneration Through Fiber-Based Physical Cues Daniel Blair, Georgetown University, USA Flow Induced Stiffening in Extensile Active Matter Marianne Grognot, RWTH Aachen University, Germany Just Keep Swimming: Structural Adaptations in Vibrio Species for Navigation in Complex Environments Cristoph Schmidt, Duke University, USA A Contracting Cytoskeletal Network Organizes into a Self-Centering Swimmer

13:30 – 14:00

14:00 – 14:30

14:30 – 15:00

15:00 – 15:30

15:30 – 16:00

Coffee Break

Delta/Omega Room

Session V

Short Talks I Chair: Guntars Kitenbergs, University of Latvia, Latvia

16:00 – 16:20

Tomohiro Mimura, Kyoto University, Japan* Proliferation-Driven Active Flows Induce Fluidization and Ordering in Multicellular Systems Aleksandra Ardaševa, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland* Topological Defects and Cell-Matrix Feedback Govern Myoblast Fusion

16:20 – 16:40

Wednesday, July 22, 2026 8:30 – 13:00

1 st Floor Lobby

Registration & Information

Session VI

Short Talks II Chair: Mara Šmite, University of Latvia, Latvia

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Daily Schedule

9:00 – 9:20

Nuno Santos, University of Lisbon, Portugal* From Erythrocyte-Based Cardiovascular Risk Assessment to the Development of Synthetic Erythrocytes Joon Ho Kang, Seoul National University, South Korea* Emergent Anisotropic Volume Regulation in Active Tissue Monolayers Revealed by High-Speed 3D Topographic Profiling Serapion Pyrpassopoulos, Center for Molecular Biology of Plants, Germany* Mechanical Tension Extends the Microtubule Lattice and Modulates Kinesin-1 Binding in an Isoform-Dependent Manner Mingming Wu, Cornell University, USA* Compression Induced Vortical Motion Within an Epithelial Spheroid Guntars Kitenbergs, University of Latvia, Latvia* Controlling Magnetic Field Induced Collectives of Magnetotactic Bacteria Near a Wall

9:20 – 9:40

9:40 – 10:00

10:00 – 10:20

10:20 – 10:40

10:40 – 11:30

Coffee Break

Delta/Omega Room

Session VII

Hydrodynamics Chair: Andrejs C ē bers, University of Latvia, Latvia

11:30 – 12:00

Hannah Yevick, Brandeis University, USA Structure, Reorganization, and Robustness of Large Multinucleated Cells Konstantin Kornev, Clemson University, USA Insect Antennae as Inspirational Self-Healing Fiber-Based Microfluidics M. Taher A. Saif, University of Illinois Urbana-Champaign, USA It Needs Three, at Least, to Raise a Cellular Family

12:00 – 12:30

12:30 – 13:00

13:00

Lunch on Own & Free Time

Thursday, July 23, 2026 13:00 – 16:00

1 st Floor Lobby

Registration & Information

Session VIII

Mechanobiology I Chair: Alison Patteson, Syracuse University, USA

9:00 – 9:30

Katarzyna Pogoda, The Henryk Niewodniczański Institute of Nuclear Physics, Poland Matrix Stress Relaxation Promotes Glioblastoma Cell Migration in a Ligand-Specific Manner

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Daily Schedule

9:30 – 10:00

Rebecca Wells, University of Pennsylvania, USA Solid Stress and Its Relationship to Cell and Matrix Organization Anders E. Carlsson, Washington University of St. Louis, USA How Molecular-Level Motor Forces Add Up to Large-Scale Stresses Luciana Bruno, University of Buenos Aires, Argentina Shaping And Moving Mitochondria: The Role of Cytoskeletal Forces

10:00 – 10:30

10:30 – 11:00

11:00 – 11:30

Coffee Break

Delta/Omega Room

Session IX

Mechanobiology II Chair: Alison Patteson, Syracuse University, USA Josef A. Käs, University of Leipzig, Germany Does Oncology Need the Physics of Cancer?

11:30 – 12:00

12:00 – 12:30

David Sept, University of Michigan, USA Effects Of Tubulin Isotypes on Microtubule Function and Dynamics Cynthia Reinhardt-King, Rice University, USA Microenvironmental Regulation of Cellular Mechanometabolism

12:30 – 13:00

13:00 – 14:00

Group Photo & Lunch

Delta/Omega Room

14:00 – 16:00

Poster Session

Delta/Omega Room

16:00 – 18:00

Tour of Riga

18:00 – 20:00

Banquet Dinner

Gutenbergs, Terase I

Friday, July 24, 2026 8:30 – 13:00

1 st Floor Lobby

Registration & Information

Session X

Engineered Systems Chair: Paul Janmey, University of Pennsylvania, USA

9:00 – 9:30

Timo Betz, Georg August University of Göttingen, Germany Accessing Active Mechanics in Living Systems from Passive Particle Trajectories

9:30 – 10:00

Daniel Fletcher, University of California, Berkeley, USA Environment-Driven Active Matter

10:00 – 10:30

Peter Galie, Rowan University, USA Biophysical Approaches to Remodel and Perfuse Organoid Vasculature

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Daily Schedule

10:30 – 11:00

Ayelet Lesman, Tel Aviv University, Israel Micropatterned Cell-Gel Systems for Studying ECM Mechanical Remodeling and Cellular Interactions

11:00 – 11:30

Coffee Break

Delta/Omega Room

Session XI

Keynote Talk & Closing Remarks Chair: Paul Janmey, University of Pennsylvania, USA

11:30 – 12:25

David Weitz, Harvard University, USA Filament Structure Determined by Protein Phase Behavior in Cells

12:25 – 12:30

Guntars Kitenbergs, University of Latvia, Latvia Closing Remarks

*Contributed talks selected from among submitted abstract s

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Speaker Abstracts

SPEAKER ABSTRACTS

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Monday Speaker Abstracts

DYNAMICS OF CYTOSKELETAL FILAMENTS INSIDE CELLULAR TETHERS Sarah Keary 1 ; Antonin Marteau 1 ; Benjamin Bouchet 2 ; Anna Akhmanova 2 ; Patricia Bassereau 1 ; 1 Institut Curie, CNRS UMR168, Physics of Cells and cancer, Paris, France 2 University of Utrecht, Faculty of Science, Utrecht, The Netherlands Pulling membrane tethers from cells and measuring the associated force—e.g., using a bead trapped with optical tweezers—is a widely used method to probe plasma membrane tension. However, actin filaments can grow within these nanotubes, whereas microtubules have not been observed inside them under normal conditions. When actin filaments reach the tip of the nanotube, they change the tether force either by pushing on the bead through polymerization or by pulling due to retrograde flow in the cortex. We will discuss the parameters that govern the dynamics of the tether forces under normal conditions and upon actin depolymerization, where we evidence that microtubules can grow inside them. INTEGRIN ADHESION COMPLEXES SENSING SUBSTRATE NANO-TOPOGRAPHY Alexander D. Bershadsky 1,2 1 Mechanobiology Institute, National University of Singapore, Singapore 117411, Republic of Singapore. 2 Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel. While role of focal adhesions in cell mechanosensitivity is well documented and intensely studied, the mechanisms of adhesion dependent topography sensing are insufficiently understood. Here we compare and contrast focal adhesions and two other major types of integrin-mediated cell-matrix adhesions – fibrillar adhesions and podosomes - and demonstrate that, unlike focal adhesions, both can recognize and selectively adhere to the matrix nano topographical features. Fibrillar adhesions are associated with cell-derived fibrils containing protein fibronectin and are required for fibrillogenesis. They rapidly align along pre-existing fibrous cell-derived matrix or electrospun nanofibers and can then template new fibronectin fibrils. Topography- induced fibrillar adhesions depend primarily on α5β1 -integrin clustering and disassemble upon excessive activation of myosin IIA or increase of membrane tension. We propose a generic theoretical model where the adhesion receptor favors the membrane and substrate planes to be tilted relative to each other. This model matches experimental observations of preferential α5β1 -integrin clustering along nanofibers and high curvature concave edges of micro-ridges. Podosomes, micron-sized dynamic adhesive membrane protrusions, also demonstrate sensitivity to myosin IIA activation and membrane tension and strong preference to the substrate features of high negative curvature. Podosome-forming cells are accumulated on substrate covered with nanopillars assembling collar adhesions consisting of 2-4 podosomes around the pillar base. Switching from podosome to focal adhesion formation by activation of Rho/ROCK/myosin IIA pathway switches cell preference from pillar-covered to flat substrate. Thus, both fibrillar adhesions and podosomes, despite compositional and structural differences, share the ability to sense substrate topography, essential for their biological functions.

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Tuesday Speaker Abstracts

NEXT-GENERATION BIOMEDICAL ENGINEERING: OPPORTUNITIES AND EMERGING DIRECTIONS Manana Sukhareva ; 1 National Institute of Health, National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD, USA This presentation will provide a programmatic perspective on emerging opportunities and strategic directions in biomedical engineering and biophysics, highlighting current priorities at the National Institutes of Health (NIH) and the National Institute of Biomedical Imaging and Bioengineering (NIBIB). The discussion will focus on the development of innovative technologies, instruments, platforms, and methodologies that expand researchers’ ability to measure, model, and manipulate biological systems. Areas of growing interest across NIH include advanced imaging and sensing technologies, biofabrication and tissue engineering platforms, synthetic biology tools, biomaterials, artificial intelligence–enabled technologies, and computational approaches that support quantitative and predictive biology. Particular attention will be given to emerging technologies and New Approach Methodologies (NAMs) that have the potential to improve the physiological relevance, scalability, and predictive value of experimental systems. From a research administration perspective, the presentation will discuss opportunities for the biomedical engineering community to advance NIH priorities through technology innovation, interdisciplinary collaboration, convergence science, and the development of broadly enabling research tools. The talk will also highlight the role of biomedical engineering in addressing fundamental biological questions and accelerating the translation of discoveries into biomedical applications. In addition, the presentation will provide insights into NIH and NIBIB approaches for supporting investigator-initiated research, technology development, interdisciplinary team science, workforce development, and international collaboration. A dedicated question-and-answer session will provide attendees with an opportunity to engage directly with the Program Director regarding NIH research priorities, funding opportunities, career development programs, and emerging directions in biomedical engineering.

EUROPEAN RESEARCH COUNCIL: FUNDING FOR FRONTEIR RESEARCH Janne Salo 1 ; 1 European Research Council, Brussels, Belgium

No Abstract

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Tuesday Speaker Abstracts

UNRAVELING THE ROLE OF VIMENTIN IN CELL MIGRATION Alison Patteson 1 ; 1 Syracuse University, Syracuse, New York, USA

No Abstract

ACTIVELY DRIVEN LIPID ASYMMETRY CREATES UNIQUE PLASMA MEMBRANE PROPERTIES Kandice R. Levental 1 ; Milka Doktorova 2 ; Ilya Levental 1 ; 1 University of Virginia, Molecular Physiology and Biophysics, Charlottesville, VA, USA 2 Stockholm University, Department of Biochemistry and Biophysics, Solna, Sweden The plasma membrane is the interface between the external world and a cell’s internal chemistry, and must therefore facilitate a multitude of parallel, tightly regulated tasks. To achieve this functional complexity, mammalian cells produce hundreds of lipid species, nearly all of which are actively asymmetrically distributed between the two leaflets of the plasma membrane bilayer. Using quantitative lipidomics we determined the asymmetric distribution of all phospholipids in human erythrocyte plasma membranes. In addition to defining the asymmetric lipidomes of the two PM leaflets, we discovered that the cytoplasmic leaflet contains ~50% more phospholipids than the exoplasmic leaflet. We show that this imbalance of phospholipids in the plasma membrane is enabled by the large abundance of cholesterol (~40%) in the plasma membrane, which can rapidly flip between leaflets to buffer area and mechanical stresses. Through computational and experimental approaches, we find that the combination of cholesterol’s preference for the more saturated exoplasmic lipids and the overabundance of lipids in the cytoplasmic leaflet yields a major enrichment of cholesterol in the exoplasmic leaflet. We show that this out-of-equilibrium distribution can be manipulated by changing the determinants of cholesterol asymmetry, namely the disparity in phospholipid composition and abundance between leaflets. Addition of phospholipids to the outer leaflet redistributes cholesterol to the cytosolic leaflet of the plasma membrane, leading to cholesterol’s recognition by cytoplasmic sensor proteins (i.e. GRAMD), which transfer it to the endoplasmic reticulum for esterification into cholesterol esters and storage in lipid droplets. Thus, active transbilayer asymmetry is a central determinant of cellular lipid homeostasis.

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Tuesday Speaker Abstracts

MECHANICAL PHASE TRANSITIONS AND THE NONLINEAR RESPONSE OF BIOPOLYMER MATRICES Fred C. MacKintosh ; 1 Rice University, Chemical and Biomolecular Engineering, Houston, TX, USA The mechanics of cells and tissues are largely governed by scaffolds of filamentous proteins. Particularly common examples of these are the collagen fiber networks of extracellular matrices. There is now increasing evidence that the mechanics of such fibrous structures are governed by underlying mechanical phase transitions reminiscent of the rigidity transition identified by Maxwell for macroscopic engineering structures: networks of struts or springs exhibit a continuous, second-order phase transition at the isostatic point, where the number of constraints imposed by connectivity just equals the number of mechanical degrees of freedom. By contrast, fibrous networks in 3D exhibit a line of critical transitions as a function of strain rather than connectivity. These transitions have shown remarkable richness, including non-mean-field critical behavior. We will present recent theoretical predictions and experimental evidence for such strain-controlled mechanical phase transitions in biopolymer networks, as well as some of the resulting elastic and viscoelastic signatures and anomalies such as an unexpectedly large Poisson ratio, slow stress relaxation and a divergent viscosity. DIRECTING REGENERATION THROUGH FIBER-BASED PHYSICAL CUES Treena Arinzeh 1 ; 1 Columbia University, Biomedical Engineering, New York, NY, USA The field of tissue engineering has expanded rapidly through the convergence of stem cell biology, emerging bioactive therapeutics, and the development of biomaterials capable of modulating cellular behavior. This talk will describe recent work investigating the physical properties of fibrous matrices, namely topographical cues and an understudied phenomena of electromechanical behavior or piezoelectricity, and how they drive changes in cell behavior. Piezoelectric fibrous scaffolds offer a biomaterials-based approach to couple mechanical deformation with localized electrical signaling, enabling dynamic regulation of cellular behavior. Our work demonstrates that piezoelectric fibers can direct stem and progenitor cell differentiation and organization in the absence of externally applied electrical fields. Through the integration of fiber architecture and electromechanical properties, these scaffolds provide multiscale physical cues that influence lineage specification and tissue formation. More recently, we have extended this platform through functionalization strategies, including the complexation of lipid nanoparticles for immune engineering applications. Interestingly, transient functionalization can be achieved without compromising the intrinsic piezoelectric properties of the scaffold, positioning piezoelectric fibrous scaffolds as modular systems for integrating bioelectric and biochemical signals in regenerative medicine.

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Tuesday Speaker Abstracts

FLOW INDUCED STIFFENING IN EXTENSILE ACTIVE MATTER Daniel Blair 1 ; 1 Georgetown University, Washington, DC, USA

No Abstract

JUST KEEP SWIMMING: STRUCTURAL ADAPTATIONS IN VIBRIO SPECIES FOR NAVIGATION IN COMPLEX ENVIRONMENTS Marianne Grognot 1 ; 1 RWTH Aachen University, Institute of Medical Microbiology, Aachen, Germany About half of bacterial pathogens can swim by rotating one or more flagella. Motility and chemotaxis (altogether termed navigation) can improve processes such as survival, dispersal or infection. Yet most navigation studies concentrate on E. coli in buffe r, overlooking the diverse strategies employed by other species in more realistic, complex habitats. This talk offers a quantitative dive into the motility and chemotaxis of two Vibrio species with a polar flagellum and distinct adaptive morphologies linked with virulence: Vibrio cholerae can increase its cell body curvature while Vibrio alginolyticus can express an additional set of lateral flagella. Using a multiscale chemotaxis assay leveraging high-throughput 3D tracking [1] , we quantified their navigation performances in buffer, soft agar hydrogels, and viscous polymer solutions (PVP).In simple buffer, V. cholerae’s curvature had little effect on navigation (compared to its straight shape), while V. alginolyticus’ lateral flagella significantly decreased swimming speed and chemotactic performances (compared to its polar-flagellum-only phenotype). In agar hydrogels both body-curvature and lateral flagella improved swim extents between traps/stalls in the hydrogels’ mesh, near doubling their chemotactic performances. In non-Newtonian PVP, lateral flagella also improved swimming speed and chemotaxis of V. alginolyticus while cell-body curvature of V. cholerae did not. Notably, expression of lateral flagella incurred a significant growth rate penalty, whereas curvature had no such cost. Altogether, these works [2][3] suggest a fascinating and complex landscape of bacterial adaptation where cell-body curvature and lateral flagella are two examples of distinct adaptive strategies for improving bacterial navigation in complex environments. References[1] Grognot & Taute, Commun. Biol., 2021.[2] Grognot et al., "Physiological adaptation in flagellar architecture improves Vibrio alginolyticus chemotaxis in complex environments", PNAS, 2023.[3] Malik et al., "Cell-body curvature modulates stall frequency to enhance Vibrio cholerae swimming and chemotaxis through hydrogels", available on bioRxiv.

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Tuesday Speaker Abstracts

A CONTRACTING CYTOSKELETAL NETWORK ORGANIZES INTO A SELF CENTERING SWIMMER Christoph F. Schmidt 1 ; Jianguo Zhao 1,2 ; Charlie Duclut 2,3,4 ; Abhinav Singh 5,6,7 ; Rahil Golipour 8 ; An Pham 1 ; Behzad Golshaei 1 ; Chonglin Guan 1 ; Mingru Li 1 ; Dieter R Klopfenstein 9 ; Rudolf Oldenbourg 10 ; Ivo F Sbalzarini 5,6,11 ; Stephan W Grill 5,7,11 ; James L Harden 8 ; Frank Jülicher 2,7,11 ; 1 Duke University, Department of Physics and Soft Matter Center, Durham, NC, USA 2 Max Planck Institute for the Physics of Complex Systems, Dresden, Germany 3 Institut Curie, Laboratoire Physico-Chimie, Paris, France 4 Université Paris Cité, Laboratoire Matière et Systèmes Complexe, Paris, France 5 Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany 6 TU Dresden, Faculty of Computer Science, Dresden, Germany 7 Center for Systems Biology Dresden, Dresden, Germany Active, collective cytoskeletal flow patterns drive many processes in eukaryotic cells. The physical mechanisms underlying the emergence of mesoscale flow of the cytoskeleton are still not well known. We here reconstituted an active cytoskeleton in water-in-oil emulsion droplets filled with Xenopus Laevis egg extract to study a model system that includes the full molecular complexity of the cytoskeleton and its non-equilibrium dynamics. The actin network remained isotropic, while a 3D radially convergent steady-state flow emerged, driven by actomyosin contraction and maintained by continuous actin turnover. We present a hydrodynamic computational model that treats the actin network as an isotropic active viscoelastic gel and suggests that connectivity percolation of actin filaments is essential for the observed flow velocity and density profiles. We introduce the concept of the cytoskeletal network as an exotic active swimmer that can sense boundaries without being physically attached, which leads to the observed robust centering of phase-separated inclusions. 8 University of Ottawa, Department of Physics, Ottawa, ON, Canada 9 University of Göttingen, Third Institute of Physics, Göttingen, Germany 10 Marine Biological Laboratories, Woods Hole, MA, USA 11 TU Dresden, Cluster of Excellence Physics of Life, Dresden, Germany 12 TU Dresden, Biotechnology Center, Dresden, Germany

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Tuesday Speaker Abstracts

PROLIFERATION-DRIVEN ACTIVE FLOWS INDUCE FLUIDIZATION AND ORDERING IN MULTICELLULAR SYSTEMS Tomohiro Mimura 1 ; Yasuhiro Inoue 1 ; 1 Kyoto university, Microengineering, Kyoto, Japan Collective cell migration in multicellular tissues has often been described using active matter models in which cells are treated as self-propelled particles. In these systems, tissue mechanics depend on cell density, and a transition from fluid-like to solid-like behavior, referred to as the jamming transition, has been reported. This transition has been linked to processes such as wound healing and cancer invasion. In most of these studies, activity is introduced through cell motility, while cell proliferation is not explicitly considered. However, in living tissues, cells continuously divide. Each division event locally increases cell number and generates mechanical perturbations, which can influence collective motion.In this study, we examine a system in which cells divide continuously in a two-dimensional layer. Under these conditions, the tissue does not become arrested at high density. Instead, we observe persistent collective motion with vortex like structures. As cell density increases, cell mobility also increases. In addition, cell arrangements become more ordered over time. These observations indicate that proliferation can drive collective dynamics in a way that differs from motility-driven systems.

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Tuesday Speaker Abstracts

TOPOLOGICAL DEFECTS AND CELL-MATRIX FEEDBACK GOVERN MYOBLAST FUSION Yoann Le Toquin 3 ; Sushil Dubey 4,7,8 ; Aleksandra Ardaševa 1,2 ; Lakshmi Balasubramaniam 4,5 ; Emilie Delaune 3 ; Valérie Morin 3 ; Amin Doostmohammadi 2 ; Christophe Marcelle 3,6 ; Benoît Ladoux 4,7,8 ; 1 École Polytechnique Fédérale de Lausanne (EPFL), School of Life Science, Lausanne, Switzerland 2 University of Copenhagen, Niels Bohr Institute, Copenhagen, Denmark 3 Université Claude Bernard Lyon1, INMG, Lyon, France 4 Université Paris Cité, Institut Jacques Monod, Paris, France 5 University of Cambridge, Wellcome Trust / CRUK Gurdon Institute, Cambridge, United Kingdom 6 Monash University , Australian Regenerative Medicine Institute, Clayton, Australia 7 Friedrich-Alexander Universität Erlangen-Nürnberg, Department of Physics, Erlangen, Germany 8 Max-Planck-Zentrum für Physik und Medizin, Erlangen, Germany Myoblast fusion into myotubes is critical for muscle formation, growth, and repair. While the cellular and molecular mechanisms regulating this process are increasingly understood, the role of biomechanics remains largely unexplored. Here, we combine in vitro experiments with an active nematic theoretical framework to demonstrate that a feedback loop between cell mechanics and cell-generated stresses governs myoblast fusion. Here, we present experimental results showing that myoblast and myotube organization follows principles analogous to active liquid crystals. In particular, fusion events are spatially localized at comet-shaped topological defects in the cellular alignment field, which coincide with regions of elevated compressive stress. We then introduce a minimal theoretical framework in which the myoblasts are depicted as an active nematic coupled to extracellular matrix (ECM) dynamics, which is actively remodeled by myoblasts. The model shows that ECM deposition both reflects and reinforces nematic organization, leading to enhanced stress localization at defects. This coupled description quantitatively reproduces the observed self-organization patterns and predicts the stress landscapes that regulate fusion, in agreement with experimental measurements. Together, these results establish a predictive framework linking active stresses, topological defects, and time evolving ECM interactions in myogenesis, highlighting the central role of active matter physics in tissue morphogenesis.

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Wednesday Speaker Abstracts

FROM ERYTHROCYTE-BASED CARDIOVASCULAR RISK ASSESSMENT TO THE DEVELOPMENT OF SYNTHETIC ERYTHROCYTES Catarina S Lopes 1,2 ; Ryan Gouveia e Melo 2,3 ; Luís Mendes Pedro 2,3 ; Filomena A Carvalho 1,2 ; Nuno C. Santos 1,2 ;

1 GIMM – Gulbenkian Institute for Molecular Medicine, Lisbon, Portugal 2 Universidade de Lisboa, Faculdade de Medicina, Lisbon, Portugal 3 Hospital de Santa Maria, Lisbon, Portugal

Erythrocytes are deformable cells that undergo progressive changes affecting blood flow 1 . We have previously demonstrated the biomedical relevance of the measurement of single-molecule fibrinogen-erythrocyte receptor binding and erythrocyte-erythrocyte adhesion, using atomic force microscopy (AFM)-based force spectroscopy, at the level of clinical prognosis in heart failure 2 and essential arterial hypertension 3,4 patients. This involves the measurement of erythrocyte biomechanical properties, protein-cell interactions and cell-cell adhesion, and further combining AFM studies with the measurement of hemorheology parameters such as erythrocyte deformability, erythrocyte aggregation and blood viscosity. The adhesion between human erythrocytes was further assessed by comparing AFM-based force spectroscopy measurements with micropipette aspiration. These data were used for the development of a physical/mathematical model of the biomedical relevant interaction between erythrocytes 5 . Recently, we evaluated changes in fibrinogen-erythrocyte and erythrocyte-erythrocyte interactions in carotid artery disease (CAD) patients and characterized the biomechanical properties of atherosclerotic plaques from CAD patients. Blood collected from CAD patients, before and after endarterectomy surgery (3-year follow up) was analyzed and compared with healthy blood donors. This study, comprising hemorheological parameters, erythrocyte interactions, and cell biomechanical properties, provided clinically relevant data on post-surgery improvement of patients and the evolution of the restenosis process. In parallel, we are participating in the development of a synthetic erythrocyte aimed at overcoming limitations on blood availability for transfusions, combining the lipid membrane with a cytoskeleton of self assembled peptides or DNA origami. 1. Domingues, M.M., Carvalho, F.A., Santos, N.C., 2022, Annu. Rev. Biophys. 51:201-221. 2. Guedes, A.F., et al., 2016, Nature Nanotechnol. 11:687-692. 3. Guedes, A.F., et al., 2017, Nanoscale, 9:14897-14906. 4. Guedes, A.F., et al., 2019, Nanoscale, 11:2757-2766. 5. Lopes, C.S., et al., 2023, Commun. Biol. 6:192.

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Wednesday Speaker Abstracts

EMERGENT ANISOTROPIC VOLUME REGULATION IN ACTIVE TISSUE MONOLAYERS REVEALED BY HIGH-SPEED 3D TOPOGRAPHIC PROFILING Daeeun Shin 1 ; Jimin Park 1 ; Andrew Choi 2,3 ; Teemu Miettinen 4 ; Joon Ho Kang 1,5,6 ; 1 Seoul National University, Mechanical Engineering, Seoul, South Korea 2 Hanyang University, Mechanical Design and Engineering, Seoul, South Korea 3 BK21 FOUR ERICA-ACE Center, Hanyang University, Mechanical Engineering, Ansan, South Korea 4 Koch Institute for Integrative Cancer Research, MIT, Cambridge, MA, USA Tissue monolayers are active living matter whose three-dimensional (3D) architecture and mechanical remodeling regulate tissue function, yet rapid and continuous topographic monitoring remains difficult. Here, we present Fluorescence exclusion for monolayers (FLEXOM), a microfluidic platform that combines multilayered micropillars with negative staining optics to transform each wide-field image into a self-calibrated 3D height map. Geometry-anchored reference cavities integrated into the chip retain calibration standards beneath confluent monolayers, enabling continuous 3D topographic profiling from isolated cells to confluent sheets with sub-second temporal resolution (~250 ms per frame), sub-micrometer axial precision (~0.37 µm), and multi-day biocompatibility and stability (>96 h). Using this platform, we identify two key emergent anisotropic dynamics: First, different monolayer types show distinct vertical thickness profiles despite comparable lateral footprints. Two vertical topography parameters, the mean and standard deviation of height, classify constituent cells more accurately than nine 2D descriptors, including area, circularity, and convexity (95% vs. 76%) . Second, under acute osmotic shock, vertical topographic dynamics are anisotropic in both space and time: height changes drive and precede the overall volume response, causing temporal decoupling between vertical and lateral remodeling. Surprisingly, cyclic isotonic–hypotonic pulses every 3 min can restrict remodeling entirely to the vertical axis. Overall, our work provides a new tool for high-resolution 3D profiling and establishes a framework for analyzing topographic responses of active living matter along distinct spatial axes. 5 Seoul National University, Bioengineering, Seoul, South Korea 6 Institute of Advanced Machines and Design, Seoul, South Korea

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Active and Responsive Soft Matter: From Biological to Engineered Systems

Wednesday Speaker Abstracts

MECHANICAL TENSION EXTENDS THE MICROTUBULE LATTICE AND MODULATES KINESIN-1 BINDING IN AN ISOFORM-DEPENDENT MANNER Yannic Lurz 1 ; Benedikt Fischer 1 ; Jaya Mishra 2 ; Laura Muras 1 ; Erik Schäffer 1 ; Nisha Mohd Rafiq 2 ; E. Michael Ostap 3 ; Igor Kulic 4 ; Serapion Pyrpassopoulos 1 ; 1 University of Tübingen, Center for Plant Molecular Biology, Tübingen, Germany 2 University of Tübingen, Interfaculty Institute of Biochemistry , Tuebingen, Germany 3 University of Pennsylvania, Department of Physiology, Philadelphia, PA, USA 4 CNRS, Institute Charles Sadron, Strasbourg, France Recent work has shown that the microtubule lattice possesses remarkable structural plasticity, with its conformation modulated by microtubule-associated proteins and motor proteins. However, how this plasticity responds to mechanical forces remains poorly understood. Here, we developed optical tweezers and fluorescence microscopy assays to measure the effect of tensile forces on single microtubules. Decorating microtubules with quantum dots enabled nanometre precision measurement of mechanical lattice distortions of ~0.33% under a mean tensile force of ⟨ ΔF ⟩ = 10.4 pN, within the range F min = 1.29 pN to F max = 20.4 pN — comparable to forces generated by one to three kinesin-1 or cytoplasmic dynein motors. Within this force range, the mean binding rate of KIF5B decreased within seconds by ~20% and its mean dissociation rate increased by ~10%, resulting in a reduction in mean run length. This response was not uniform across microtubules subjected to similar tensile forces; in extreme cases, run length decreased by up to 46% under tension. Substantial heterogeneity was also observed along individual microtubules, where distinct lattice regions responded differently to applied force, implying that tensile-force-induced lattice expansion is not always uniform along a single microtubule. Similar heterogeneity was observed in cells: when MAPs with competing conformational preferences are overexpressed, they assemble in non-overlapping patches along the same microtubule. These observations are consistent with a dynamic polymorphic lattice model, in which mechanical stress differentially stabilises distinct structural configurations, as supported by Brownian dynamics simulations and a statistical mechanical Ising model based on the conformational bistability of the tubulin building block. Strikingly, no statistically significant effects were observed for KIF5C within the same force range, revealing an isoform-dependent mechanoresponse. Together, these findings establish microtubules as bona fide mechanochemical signal transducers, converting mechanical forces into biochemical signals across distances spanning the cell body with the speed and sensitivity required for rapid cellular responses.

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