| dc.description.abstract | The treatment of critical-sized bone defects poses significant challenges as these defects often require
medical intervention. The gold standard treatment, autologous bone grafts, has drawbacks like donor
site morbidity and limited tissue availability. In response, the field of bone tissue engineering (BTE)
emerged, aiming to develop biological substitutes or scaffolds utilizing biomaterials, cells, and growth
factors to regenerate bone. However, challenges such as insufficient vascularization still hinder clinical
translation. Nonetheless, endochondral bone regeneration (EBR) is a BTE approach that holds
promise. It involves mimicking a soft callus to serve as template for bone regeneration.
This thesis focuses on advancing the EBR research of our group by developing a bioink containing
chondrogenic micro pellets. A microwell system was selected to generate micro pellets, which were
cultured across four mesenchymal stem cell donors. Seven different cell densities (1500, 3000, 6000,
12000, 24000, 36000, and 50,000 cells per micro pellet) and a control (250,000 cells per macro pellet)
were analyzed for size and chondrogenic differentiation with a safranin-O, toluidine blue, and collagen
II staining. In continuation, micro pellets were combined with Gelatin Methacryloyl (GelMA) to create
a bioink, which was cast and volumetrically printed to demonstrate functionality by fabricating an
incus bone shape.
The microwell system of the Inge Zuhorn group was chosen for further optimization instead of
microwell stamps. Micro pellets under 6000 cells displayed limited to no GAG and collagen II
deposition. Above 6000 cells, micro pellets demonstrated unwanted aggregation but exhibited
complete GAG and collagen II deposition. Due to these issues, a second bioink, composed of crushed
macro pellets and GelMA, was formulated. The macro pellets were effectively crushed and integrated
into bioink and used to volumetrically print an incus bone.
In conclusion, a microwell system was selected, the initial steps to optimize micro pellet culture were
taken, and a successful bioink for EBR was formulated and printed. Optimizing and standardizing
chondrogenic micro pellet culture, bioink formulation, and printing through further experimentation
is recommended for future applications. | |
