ABSTRACT
Spheroids derived from human mesenchymal stem cells (hMSCs) are of limited use for cartilage regeneration, as the viability of the cells progressively decreases during the period required for chondrogenic differentiation (21 days). In this work, spheroids based on hMSCs and a lactose-modified chitosan (CTL) were formed by seeding cells onto an air-dried coating of CTL. The polymer coating can inhibit cell adhesion and it is simultaneously incorporated into spheroid structure. CTL-spheroids were characterized from a morphological and biological perspective, and their properties were compared with those of spheroids obtained by seeding the cells onto a non-adherent surface (agar gel). Compared to the latter, smaller and more viable spheroids form in the presence of CTL as early as 4 days of culture. At this time point, analysis of stem cells differentiation in spheroids showed a remarkable increase in collagen type-2 (COL2A1) gene expression (~700-fold compared to day 0), whereas only a 2-fold increase was observed in the control spheroids at day 21. These results were confirmed by histological and transmission electron microscopy (TEM) analyses, which showed that in CTL-spheroids an early deposition of collagen with a banding structure already occurred at day 7. Overall, these results support the use of CTL-spheroids as a novel system for cartilage regeneration, characterized by increased cell viability and differentiation capacity within a short time-frame. This will pave the way for approaches aimed at increasing the success rate of procedures and reducing the time required for tissue regeneration.
Subject(s)
Cell Differentiation , Chitosan , Chondrogenesis , Lactose , Mesenchymal Stem Cells , Spheroids, Cellular , Chitosan/pharmacology , Chitosan/chemistry , Mesenchymal Stem Cells/drug effects , Mesenchymal Stem Cells/cytology , Humans , Cell Differentiation/drug effects , Chondrogenesis/drug effects , Spheroids, Cellular/drug effects , Spheroids, Cellular/cytology , Lactose/pharmacology , Lactose/chemistry , Cell Survival/drug effects , Cells, Cultured , Collagen Type II/metabolism , Collagen Type II/geneticsABSTRACT
O objetivo do presente trabalho foi avaliar o comportamento superficial do titânio utilizado nas conexões de implantes osseointegrados quando em contato com o flúor tópico acidulado. Uma conexão de titânio vanádio alumínio foi analisada em Microscopia Eletrônica de Varredura (MEV). As análises foram realizadas em tempo zero, antes do emprego de gel de flúor fosfato acidulado e 4, 8 e 12 minutos pós imersão no gel de flúor. Na análise da morfologia da conexão, antes e após os ensaios de imersão, observou-se reação entre o gel de flúor e a superfície do titânio, com mudança na aparência externa e formação de defeitos microestruturais com características de corrosão. Os resultados sugerem que a aplicação tópica de gel de flúor fosfato acidulado deve ser cuidadosamente selecionada e prescrita em pacientes portadores de próteses osseointegradas com exposição da conexão de titânio
