Hyaluronic acid and dextran hydrogels for tissue engineering applications

Hydrogels have become vital tools in tissue engineering, especially in repairing and replacing tissues. Hyaluronic acid (HA)-based and dextran (Dex)-based hydrogels hold significant promise in this field. While research shows encouraging results, particularly in controlled lab environments, challenges remain in their use for bioprinting complex structures, ensuring bioactivity, and developing injectable solutions for cartilage defects. Additionally, transitioning lab successes to clinical applications is hindered by the complexity of these strategies.
This thesis focuses on three key areas: advanced 3D bioprinting, bioactivity studies, and injectability for defect repair.
Chapter 2 provides a review of hydrogel-based bioinks for coaxial and triaxial bioprinting, highlighting their potential in tissue engineering. Chapter 3 presents a one-step approach for coaxial bioprinting using high molecular weight hyaluronic acid-tyramine (HA-TA) bioinks, showing promising initial results in cell viability but identifying a need for further research to enhance cell proliferation.
Chapter 4 reviews injectable hydrogels for cartilage repair, focusing on biocompatibility, mechanical properties, and current clinical trials. Chapter 5 explores the chondrogenic potential of HA-based hydrogels with varying molecular weights, noting that softer hydrogels promoted higher cell viability and the additional effect of gelatin-tyramine (Gel-TA) to the hydrogel (HA-TA) system. Different molecular weights affected degradation rates and cartilage matrix deposition. The study suggests further optimization to improve mechanical properties and bioactivity.
Chapter 6 investigates the use of injectable dextran-tyramine (Dex-TA) and HA-tyramine (HA-TA) hydrogels in equine cartilage defects. Although cadaver studies showed retention, live tests revealed loss of the hydrogel within a month, suggesting the need for improvements in viscosity and mechanical strength.
Chapter 7 introduces a dual-functional dextran hydrogel with maleimide and tyramine groups (Dex-TA-Mal), offering rapid crosslinking and targeted biomolecule coupling. Although cell viability slightly declined, the hydrogel remained promising for further bioactivity enhancements.
Collectively, these chapters underscore the progress in hydrogel-based bioprinting and injectable hydrogels, while emphasizing the need for continued research to overcome existing limitations and translate findings to clinical practice.