Date of Graduation

12-2025

Document Type

Thesis

Degree Name

Bachelor of Science in Chemical Engineering

Degree Level

Undergraduate

Department

Chemical Engineering

Advisor/Mentor

Dr. William Richardson

Abstract

Cardiac fibrosis (CF) is a major contributor to the high mortality rate of heart failure which affects over 23 million people worldwide. CF involves cardiac fibroblasts depositing extracellular matrix, made primarily of collagen type I, which stiffens the heart walls over time. As testing new drugs for CF is deterred by the high cost and time required for animal and clinical trials, this research helps to solve the problem by providing an in vitro platform to study fibrosis.

The work involved creating tissues containing human cardiac fibroblast (HCFB) cells. Spring testing was conducted to determine the force applied by the electromagnet at discrete amperages. Equations for calculating the applied force in high and low stretch rows were produced from this testing. After a 48-hour static hold for maturation, the gels underwent Day 0 imaging and stiffness testing, followed by 24-hour period of continuous cyclic stretching designed to mimic the beating of a human heart, and Day 1 imaging. The sample moduli were determined by measuring strain and calculating stress from force and area measurements at discrete amperage levels using the ImageJ software.

Student t-tests showed that significant stiffening occurred between Day 0 and Day 1 for both the high stretch and low stretch sample groups (p < 0.05). The high stretch gels stiffened to a greater degree of significance than the low stretch gels. Also, observation of cell morphology after one day suggested that the stiffening of the gels is related to fibroblast activity and is influenced by the degree of stretching. The results indicate that cyclic stretching successfully caused stiffening in the HCFB gels, effectively demonstrating a way to artificially induce fibrosis. Therefore, the platform can be used to test whether compounds reduce or enhance the stiffening of the gel, providing researchers with a significantly cheaper and easier method for exploring potential fibrosis medication compared to currently used tests.

Keywords

Cardiac fibrosis; cyclic stretching; extracellular matrix; Human cardiac fibroblasts; In Vitro Platform; Drug screening

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