Insights of Bone-Remodeling - Limitations and Alternatives in Bone Tissue Engineering
Year: 2021
Type: dissertation
Abstract: Defects in bone structures are extensive problems, faced by millions of people worldwide. Still, current methods do not always provide a satisfactory result in restoring functions after trauma or disease treatment. Bone tissue engineering methods require refinement; therefore, cell-derived agents could be used to enhance treatment outcomes. The extracellular vesicles (EVs) are potential new agents that could improve bone formation in tissue engineering. EVs are released from the cellular membrane and contain mRNA, miRNA and other tissue factors, affecting recipient cells. As EVs can initiate cell differentiation, it is important to understand the mechanisms behind their operation, since they have shown applicability as biomimetic tools for guided lineage-specific differentiation and cell-free therapies. In this thesis, a novel cost-effective and easily standardizable method for EV isolation was developed, based on ultrafiltration of cell culture media. The method may be used in a wide range of cell culture applications increasing reproducibility of EV research results between laboratories. As EVs are proposed to be central in intercellular communication, the potency of EVs from activated monocytes (MC) and osteoclasts was evaluated on adipose tissue mesenchymal stromal cells (MSCs). The EVs from activated MCs promoted secretion of cytokines, potentially representing an immunomodulatory mechanism, while also upregulating gene expression of matrix metalloproteinases in MSCs, affecting tissue remodeling. Further, to investigate the role of EVs in malignant bone conditions, MSCs and pre-osteoblasts were treated with EVs released from osteosarcoma cells (OS-EVs) and the epigenetic signature of OS-EVs was assessed. Overall, this study provided evidence that epigenetic regulation appears to be an early event in the transformation of MSCs during the development of OS. To develop new methods for tissue engineering, we conducted an in vivo study on minipigs. The minipig was selected as the large animal model of choice due to physiological and anatomical similarities of the jaws and teeth with humans. To reconstruct a large continuous defect in the mandible, a composite consisting of PTMC (poly[trimethylene carbonate]) and calcium phosphate ceramic was tested in a mechanically loaded area. The bioimplant scaffolds were manufactured individually based on CT imaging data from each minipig using computer-aided design and manufacturing (CAD-CAM). The mandibular defect was stabilized with custom-made 3D printed titanium reconstruction plates as the bioimplant itself was not load-bearing. The results of this thesis work investigated different strategies in bone remodeling, e.g., the effect and mechanisms of EVs on the immune system and bone remodeling as well as in malignant transformation. Further studies are necessary to confirm the proof-of-concept in bone remodeling to implement these strategies in patient treatments.
Source: Työväentutkimus Vuosikirja
Author: Roman Kornilov
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W3209203139