Designing biomimetic polymer scaffolds for bone mineralization investigation

Author(s)

Lucas Fabrício Bahia Nogueira

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC)
• Defense date: 2024-06-11

Examining board members

Ana Paula Ramos; Fausto Bruno dos Reis Almeida; Massimo Bottini; Luciane Portas Capelo

• Advisor: Ana Paula Ramos

Abstract

Bone, as a dynamic hard tissue, undergoes continuous remodeling to maintain skeletal strength and integrity. It comprises mineralization-competent cells within an extracellular matrix (ECM) primarily consisting of collagen (Col) and other non-collagenous macromolecules (NCM). Despite the development of various in vitro-based strategies to mimic the complexity of native ECM, ranging from nano- to micro-scale, precise control over the orchestrated mineralization process by mineralization-competent cells in vivo remains a considerable challenge. The physiology of bone formation shares commonalities with ectopic mineralization, characterized by the calcification of soft tissues. This phenomenon arises due to the transdifferentiation of resident cells in these connective tissues into osteochondroblast-like cells, which are responsible for producing mineralized bone ECM. Consequently, in vitro biomimetic models have been explored for studying pathological conditions. Biomimetic materials capable of replicating the ECM complexity in connective tissues, under both physiological and pathological conditions, hold promise as the next generation of biomaterials. These materials not only serve as potential artificial tissue grafts but also provide a valuable platform for in vitro modeling of pathologies, facilitating drug testing and the development of novel therapies and treatments. To address this shortcoming, this thesis proposed the development of an in vitro 3D cell culture model inspired by the organic composition of ECM found in connective tissues, such as bone and blood vessels, to assess how this organic matrix influences, both physio and pathological conditions, the interaction and activity of cells, mainly, in the acquisition of a calcifying phenotype. Among all NCM, the role of GAGs in the ECM composition was investigated using κ-carrageenan (κ-carr), as a suitable alternative to mimic its role in providing biochemical stimulation for cells to acquire a mineralizing phenotype. In addition to its chemical and structural similarities, this polysaccharide has the advantage of being extracted from renewable sources and possessing excellent gelling properties. The absence of cytotoxicity of this polysaccharide was evaluated from the production of polymeric nanoparticles which showed efficiency in the ability to transport and release curcumin in osteoblast cultures. The incorporation of κ-Carr into 3D collagen-based scaffolds stimulated both maturation and transdifferentiation of cells to acquire a mineralizing phenotype. The versatility of these biomimetic ECMs was explored in their interaction with matrix vesicles (MVs), which are secreted by cells that express the mineralizing phenotype, which play a crucial role in depositing the mineral phase in the organic matrix. Thus, the development of these biomimetic models has the potential to herald a new era in modern therapeutic targets, aiding in disease prevention. This includes the isolation of patient cells from clinical settings and seeding them into 3D cell-free scaffolds, thereby enabling the customization of treatments and reducing reliance on animal testing. (AU)

• FAPESP's process: 18/25871-8 - Scaffolds composed by bioactive glasses and injectable matrices for bone regeneration
• Grantee: Lucas Fabrício Bahia Nogueira
• Support Opportunities: Scholarships in Brazil - Doctorate