Mechanics and Physiological Adaptation of Hard and Soft Biomaterials and Biological Tissues: Soft Materials & Adaptation
Sponsored by: TMS Functional Materials Division, TMS Structural Materials Division, TMS: Biomaterials Committee
Program Organizers: Bernd Gludovatz, UNSW Sydney; Elizabeth Zimmermann, McGill University; Steven Naleway, University of Utah
Monday 8:30 AM
March 20, 2023
Room: Sapphire 400B
Location: Hilton
Session Chair: Elizabeth Zimmermann, McGill University; Bernd Gludovatz, UNSW Sydney
8:30 AM Introductory Comments
8:35 AM Keynote
Materials for Mechanochemistry and Mechanobiology: Pavithra Jayathilaka1; Thomas Molley1; Yuwan Huang1; Meredith Silberstein2; Jay Kruzic1; Kristopher Kilian1; 1UNSW Sydney; 2Cornell University
Most hydrogels used in biomedical applications display a homogenous static architecture. In contrast, natural hydrogels in tissue are highly dynamic, where internal and external forces will catalyse changes in chemistry, architecture, and mechanical properties. In this presentation I will demonstrate how materials chemistry can be used to fabricate dynamic hydrogels that mimic signaling in natural tissue. First, I will demonstrate mechanochemical linkages that release molecules in response to force. Crosslinking hydrogels with an oxanorbornadiene molecule facilitates biomolecule release through a force-mediated retro Diels-Alder reaction. Next, I will show an alternative mechanochemical approach where polymeric microcapsules are integrated within the hydrogel, and how force can trigger rupture to release bioactive molecules. Together, these mechanochemistry concepts that mimic natural processes in the extracellular matrix, provides a new approach to making force-responsive dynamic biomaterials for a broad spectrum of applications including implant adhesives and coatings, bandages, biosensors, and materials for tissue engineering.
9:15 AM Keynote
Mechanics and Applications of Bioinspired Bioadhesives for Tissue Repair: Jianyu Li1; 1McGill University
Bioadhesives form appreciable adhesion to biological tissues. Examples include blood clots, a native bioadhesive formed by the human body to seal wounds, as well as adhesive hydrogels that find increasing use in the clinic for wound management and tissue repair. Despite the significance and extensive usage of bioadhesives, the mechanics of bioadhesives remains less explored, which involves complexity of interfacial fracture, and bulk mechanics of bioadhesives and tissues. To advance mechanics of bioadhesives, our lab combines experimental, theoretical, and computational approaches to investigate the bulk and interfacial mechanics of blood clots and tough hydrogel adhesives. Specifically, my talk will discuss (1) fracture mechanics of human blood clots and derivatives; (2) scaling behavior of fracture properties of adhesive hydrogels; (3) tissue adhesion with tough hydrogels: Experiments and modeling. The understanding will be shown to promote the performance of bioadhesives in wound management, bleeding control and tissue repair.
9:55 AM Break
10:15 AM Invited
Bone Adaptation as a Response to Mechanical Loading in Zebrafish: Bjorn Busse1; 1University Medical Center Hamburg
Musculoskeletal exercise promotes bone maintenance through adaptive responses of the skeleton. This mechanism has the potential to counteract age- and disease-related bone loss. To study the effects of exercise on bone quality, zebrafish emerged as a promising vertebrate model. Bone adaptation processes in adult zebrafish have been characterized after the animals were subjected to increased physical exercise in a swim tunnel experiment. Cellular, structural and compositional changes of the loaded skeleton were quantified using high-resolution imaging and microanalyses. Exercise induced rapid bone adaptation with increases in bone-forming osteoblasts, bone volume fraction and mineralization. Modeling processes in zebrafish bone resemble processes in human bone. The study highlights how exercise experiments in adult zebrafish can contribute to affect aging-related bone diseases and can thus help to maintain bone quantity and quality.
10:45 AM Invited
Bone's Adaptation to Hyperglycemia in Diabetes: Claire Acevedo1; 1University of Utah
With the global epidemic of diabetes, understanding the mechanisms underlying diabetic bone fragility is an urgency. Contrary to standard bone fragility diseases such as osteoporosis, type 2 diabetes is not associated with a low bone mass but it is clearly caused by changes in bone quality. Using a rat model of Type 2 Diabetes Mellitus combined with multi-scale synchrotron experiments from the nanoscale to the macroscale, we demonstrate that diabetes significantly reduces whole-bone strength and toughness for a given bone mass, and we quantify the roles of T2DM-induced deficits in material properties versus bone structure in long bones, vertebrae, and discs. Deficits in material properties in diabetic rat bones are a bone adaptation to increased advanced glycation end-products and impaired collagen fibril deformation.
11:15 AM
Adaptation of Hard and Soft Tissues Structures to Physiological Loading Patterns: Elizabeth Zimmermann1; 1McGill University
Bones have the capability to adapt their shape, size and potentially their material properties to their mechanical environment: as mechanical strain on bone decreases, bone is resorbed, as mechanical strain increases, bone is formed. Most studies investigate bone adaptation through the lens of exercise or loading regimes targeting osteogenic strain levels. My research program seeks to understand the role of soft tissues, like muscles and ligaments, on bone adaptation. One classic example is cerebral palsy, where abnormal muscle tone can lead to abnormal function, bone deformities and fracture risk. The effects of cerebral palsy on bone are especially dramatic because the abnormal muscle tone and movements are applied to growing bones. Another example is the periodontal ligament, which anchors the tooth to the alveolar bone. It is unknown how the morphology of the periodontal ligament and its connection to the surrounding bone vary based on different mechanical environments.