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Session D Biomechanics
Track 1
Session D
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Biomechanics
46 BME SENIOR DESIGN PROJECTS
Novel Method for Strain Transfer Research on Murine Flexor Tendons at Cellular Level
Team 26: Gabriela Alba, Anushka Murti, Chi Chiu Victor Wong Technical Advisor: Brianne Connizzo
Tendinopathy is a highly prevalent clinical condition mainly caused by overuse or age-related degeneration of tissues. The transfer of strain from the ECM to the cell triggers extracellular matrix (ECM) remodeling. Therefore, a reduction in strain transfer could lead to a reduction in ECM remodeling and ultimately, tissue degeneration. A bioreactor with the capabilities of applying controlled loads and imaging loaded tissues would enable the study of strain transfer at the cellular level. The team inherited previously established hardware for a customized mechanical loading bioreactor, which has the potential to be used in conjunction with the Olympus FV3000 confocal microscope. The team developed two custom programs using MATLAB App Designer to control the bioreactor and analyze data. The control software performs customized experiments (Manual Movement, Imaging Protocol, and Cyclic Movement), provides real-time data of relative position of the slider and applied load on the sample, and saves data to an Excel file for further analysis. The data analysis software uses image processing and tissue-level displacement data to calculate multi-scale strains and strain transfers. Depending on the structure(s) stained in the confocal images, the software has the ability to calculate ECM-, cell-, and nucleus-level strains as well as strain transfers from tissue to ECM, ECM to cell, and cell to nucleus. Additionally, the team developed a research protocol for a future age-related experiment, which would allow Dr. Connizzo to observe strain transfer via simultaneous mechanical loading and fluorescence imaging on aged live murine flexor tendons.
Research reported in this publication was supported by the Boston University Micro and Nano Imaging Facility and the Office of the Director, National Institutes of Health of the National Institutes of Health under award Number S10OD024993. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Health.
Murine exor tendon Mechanical-loading bioreactor
Olympus FV3000 confocal microscope
Bioreactor data & confocal images used to calculate multi-scale strains & strain transfers FIJI software processes images from microscope
Custom MATLAB software to control bioreactor and collect time-dependent load & displacement data
Calculated data saved to MS Excel le
The Effect of Inflammatory Phase in Mechanobiological Modeling on Bone Fracture Healing
Team 30: Zhuojian (Jamie) Jiang, Zakarey Sharif, Hanyu (Wendy) Wang Technical Advisor: Ara Nazarian (BIDMC & Harvard Medical School))
Bone fractures are commonplace in our fast-paced society. Medicine has advanced so much that people take for granted how intricate recovery is. The healing process at the cellular level is complex and involves a cascade of reactions that occur over the course of recovery. This complexity makes it difficult to simulate the bone fracture’s progression as it heals. A successful simulation model would allow care providers to accurately track healing outcomes for their patients and catch any deviations in a timely manner. The issue is that the current framework for bone healing models is incomplete because these models fail to account for all four stages of healing (inflammatory phase, soft callus formation, hard callus formation and bone remodeling). In particular, the inflammatory stage is the most neglected stage in these models and so our team, using data collected from healthy rats , focused on this issue by constructing a computational model that simulates healing from the earliest stages of healing to bone reformation. The team created a biological expression map incorporating new RNA data to model the different growth factors that are present at the fracture site during recovery. We also updated an existing mechanical model that describes the optimal conditions of a bone fracture during recovery. It is the combination of these two models that are used to construct the new mechanobiological computational model that will simulate bone healing. This model will hopefully set a foundation for bone healing models that can be easily implemented in healthcare in the future.
Rotator Cuff Tendon Surface Strain during Glenohumeral Motion: A Cadaveric Model to Assess the Effects of Mechanical Load and Joint Position
Team 31: Andrew Miao, Zhongkun Xue Technical Advisors: Ara Nazarian (BIDMC & Harvard Medical School), Patrick Williamson (BIDMC & MechE)
The rotator cuff muscles stabilize the glenohumeral joint which consists of the humeral head and the glenoid. This ball-and-socket joint enables the shoulder to have a wide range of motion. There are four muscles that create the rotator cuff (RC): Subscapularis, Infraspinatus, Supraspinatus, and Teres Minor. Each of these RC muscles serves a unique role in movements such as adduction and rotation. Injuries such as shoulder impact or jerking movements of the shoulder are common incidents that cause a rotator cuff tear (RCT). RCTs can be a partial or full tear and symptomatic or asymptomatic. Patients are more likely to seek treatment if they have a symptomatic tear because of pain or difficulties with typical movements. Nearly two-thirds of all RCTs are asymptomatic and can be left untreated. Given that RCTs are difficult to identify and their tear progression, this creates a critical need to identify the surface strain of RC tendons from mechanical loading and joint position so that RCTs can be treated before muscle and tendon atrophy occurs. Here we propose a cadaveric study to analyze the surface strain of the supraspinatus tendon during passive adduction using an existing glenohumeral testing system and a 2D image correlation. Furthermore, we propose to apply this system to investigate the effect of RC load and joint position on tendon strain. The objective of this project is to better understand how the position of the glenohumeral joint and loading on the RC tendons affect the surface strain of the tendons.
A System for Imaging Precision Cut Lung Slices
Team 33: Keira Donnelly, Landon Kushimi, Reyn Tyler Saoit Technical Advisor: Béla Suki
Precision Cut Lung Slices (PCLS) are a reliable tool to model the biomechanical activity of lung tissue. Its numerous advantages include the retaining of nearly all resident cell types in the lung, preserving the native extracellular environment, and suitability for high resolution imaging. Recent developments of novel tissue stretchers which mimic physiological breathing patterns allow researchers to track lung pathology progression via the changing mechanical properties of the lung tissue. Tracking tissue deformation, however, is difficult due to the lack of high contrast areas within the tissue, which image processing software require for their correlation algorithms. Current solutions are constrained by a small field of view, or are limited to the imaging of a single sample. We propose the use of ink-filled beads to provide the contrast necessary for mapping areas of the tissue during stretch, and housing the camera below the sample in the indenter to avoid light scattering caused by imaging through the tissue. This technique is known as Absorption Contrast, enabling tracking of deformations via the movement of beads at resting state and stretching state. Methods used in previous studies have been employed to ensure bead homogeneity and proper binding to the tissue. The beads are illuminated through the tissue using six dimmable, white LEDs and two layers of a light diffuser to ensure even lighting. An endoscope is housed within the indenter in order to image the tissue from below, allowing us to image a large field of view of 12 samples simultaneously.
Six white LEDs for bead illumination, diffuser for homogeneity of light
PCLS
Ink-filled beads embedded in silicon gel
Flexible membrane
Endoscope housed in indenter for imaging from below the well plate
Team 42: Viet Nguyen, Gautham Salgam, Danial Shafi Technical Advisors: Aleks Zosuls, Ousama A’amar
Whales are thought of as big mammals of the ocean that are few and live for long periods of time. Amongst the middle ear bones of aquatic cetaceans there is an anatomical anomaly where different regions of the bone vary in density. Through the use of a precision saw and resin to create effective whale middle ear bone samples and a microscope camera, precise mapping of the density of the samples can begin. Recent studies have shown by using Electric Scattering Spectroscopy (ESS), one can utilize the scattering of photons at different wavelengths for the incus, malleus, and stapes of two different species of whales and relate them to the number density can be used to detail different regions of bones for multiple species. In comparison, the water displacement method could measure the mass density of the material, but not specific areas while the Basilar Membrane Probe could measure the density of the material, but fails at high hearing frequencies. In this experiment, we explore a new way to quantify and understand the density of aquatic cetacean middle ear bones and expand on making it precise by building a fixture to hold the ESS probe. The number density can be achieved through the reduced scattering coefficient found using ESS and then one can find the scattering coefficient and subsequently the number density for regions of the middle ear bone. We demonstrate that using ESS is a much better tool to quantify the density because of its accuracy and precision than other methods.
52 BME SENIOR DESIGN PROJECTS
