Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Engineering Science

Program

Biomedical Engineering

Collaborative Specialization

Engineering in Medicine

Supervisor

Paul, Arghya

Abstract

The prevalence of osteoarthritis (OA) has been increasing in ageing populations, which has necessitated the use of advanced biomedical treatments. These involve grafts or delivering drug molecules entrapped in scaffolds. However, such treatments often show suboptimal therapeutic effects due to poor half-life and off-target effects of drug molecules. This study aimed to overcome limitations associated with current treatments for OA and osteochondral defects by combining decellularized extracellular matrix (ECM) with gelatin methacryloyl (GelMA) and utilizing digital light processing (DLP) 3D printing. GelMA has shown great potential in tissue engineering due to biocompatibility and mechanical tunability. To harvest bioactive ECM, pre-osteoblastic and pre-chondrogenic mice cells were cultured in vitro and differentiated for 14 days. Decellularized ECM from these cell lines were incorporated into GelMA hydrogels to fabricate GelO and GelC hydrogels with osteogenic and chondrogenic properties, respectively. The concentrations of decellularized ECM in the hydrogels were optimized for cytocompatibility and differentiation potential. Additionally, mechanical and rheological properties, swelling, and degradation behaviour of the different hydrogel formulations were assessed. We demonstrated when human adult stem cells are grown on ECM-hydrogels (GelO or GelC) individually or in combination (GelO-GelC) for 21 days can induce osteogenic and chondrogenic differentiation as confirmed by staining techniques (Alizarin Red S and Alcian Blue S) and qPCR analysis for corresponding gene markers. Additionally, we showed that formulated ECM-hydrogels can be chemically bonded using carbodiimide-based coupling reactions to mimic the osteochondral interface. To conclude, this ECM-based bioactive hydrogel offers a promising new drug-free and cell-free treatment strategy for bone and cartilage repair, and future OA management.

Summary for Lay Audience

Osteoarthritis, a condition that affects the joints and is more common in older people, is becoming more prevalent. To treat this condition, advanced biomedical techniques are being used. These techniques involve grafting and delivering drugs. However, current treatments often have limited effectiveness due to the short lifespan of the drugs and their effects on unintended areas of the body. In this study, we aimed to overcome the limitations of current treatments for osteoarthritis by combining a bioactive material called decellularized extracellular matrix (ECM) with another material called gelatin methacryloyl (GelMA). GelMA has shown great promise in tissue engineering because it is compatible with the body and can be adjusted to have the right mechanical properties. We cultured and differentiated cells from mice to obtain bioactive ECM. These molecules were incorporated into GelMA hydrogels to create two types of hydrogels: one with properties that promote bone growth (GelO) and another that promotes cartilage growth (GelC). We also treated human stem cells with these hydrogels individually and in combination (GelO-GelC) and found that they were safe for the cells and promoted both bone and cartilage growth. We confirmed the presence of markers for bone and cartilage using special staining techniques and gene expression analysis. Lastly, we chemically bonded the hydrogels together to mimic the interface between bone and cartilage in a joint. This bioactive hydrogel offers a drug-free and cell-free approach to treating osteoarthritis by simultaneously regenerating the cartilage and bone in the affected areas of the joints.

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Available for download on Friday, August 01, 2025

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