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6 results on '"Mouser, Vivian Hilda Maria"'

1. Dynamic loading leads to increased metabolic activity and spatial redistribution of viable cell density in nucleus pulposus tissue

Author

Salzer, Elias, Mouser, Vivian Hilda Maria, Bulsink, Jurgen A., Tryfonidou, Marianna A., Ito, Keita, Salzer, Elias, Mouser, Vivian Hilda Maria, Bulsink, Jurgen A., Tryfonidou, Marianna A., and Ito, Keita

Abstract

Background Nucleus pulposus (NP) cell density is orchestrated by an interplay between nutrient supply and metabolite accumulation. Physiological loading is essential for tissue homeostasis. However, dynamic loading is also believed to increase metabolic activity and could thereby interfere with cell density regulation and regenerative strategies. The aim of this study was to determine whether dynamic loading could reduce the NP cell density by interacting with its energy metabolism. Methods Bovine NP explants were cultured in a novel NP bioreactor with and without dynamic loading in milieus mimicking the pathophysiological or physiological NP environment. The extracellular content was evaluated biochemically and by Alcian Blue staining. Metabolic activity was determined by measuring glucose and lactate in tissue and medium supernatants. A lactate-dehydrogenase staining was performed to determine the viable cell density (VCD) in the peripheral and core regions of the NP. Results The histological appearance and tissue composition of NP explants did not change in any of the groups. Glucose levels in the tissue reached critical values for cell survival (≤0.5 mM) in all groups. Lactate released into the medium was increased in the dynamically loaded compared to the unloaded groups. While the VCD was unchanged on Day 2 in all regions, it was significantly reduced in the dynamically loaded groups on Day 7 (p ≤ 0.01) in the NP core, which led to a gradient formation of VCD in the group with degenerated NP milieu and dynamic loading (p ≤ 0.05). Conclusion It was demonstrated that dynamic loading in a nutrient deprived environment similar to that during IVD degeneration can increase cell metabolism to the extent that it was associated with changes in cell viability leading to a new equilibrium in the NP core. This should be considered for cell injections and therapies that lead to cell proliferation for treatment of IVD degeneration.

Published
2023

5. Development of a thermosensitive HAMA-containing bio-ink for the fabrication of composite cartilage repair constructs

Author

Mouser, Vivian Hilda Maria, Abbadessa, Anna, Levato, Riccardo, Hennink, Wim, Vermonden, Tina, Gawlitta, Debby, Malda, Jos, dES RMSC, Pharmaceutics, dES RMSC, and Pharmaceutics

Subjects
Polymers, 02 engineering and technology, Matrix (biology), Biochemistry, Polyethylene Glycols, chemistry.chemical_compound, Tissue engineering, Taverne, Hyaluronic Acid, Child, Cells, Cultured, Glycosaminoglycans, Tissue Scaffolds, Hydrogels, General Medicine, 021001 nanoscience & nanotechnology, medicine.anatomical_structure, Child, Preschool, Self-healing hydrogels, Polycaprolactone, Fibrocartilage, Ink, methacrylated hyaluronic acid, 0210 nano-technology, Chondrogenesis, Biotechnology, Materials science, Polyesters, 0206 medical engineering, Biomedical Engineering, Bioengineering, Polyethylene glycol, macromolecular substances, Article, Biomaterials, Chondrocytes, Elastic Modulus, medicine, thermosensitive hydrogel, Journal Article, Methacrylamide, Humans, Regeneration, PCL reinforcement, Collagen Type II, Acrylamides, Tissue Engineering, Cartilage, Bioprinting, technology, industry, and agriculture, 020601 biomedical engineering, co-printing, chemistry, Biomedical engineering
Abstract

Fine-tuning of bio-ink composition and material processing parameters is crucial for the development of biomechanically relevant cartilage constructs. This study aims to design and develop cartilage constructs with tunable internal architectures and relevant mechanical properties. More specifically, the potential of methacrylated hyaluronic acid (HAMA) added to thermosensitive hydrogels composed of methacrylated poly[N-(2-hydroxypropyl)methacrylamide mono/dilactate] (pHPMA-lac)/polyethylene glycol (PEG) triblock copolymers, to optimize cartilage-like tissue formation by embedded chondrocytes, and enhance printability was explored. Additionally, co-printing with polycaprolactone (PCL) was performed for mechanical reinforcement. Chondrocyte-laden hydrogels composed of pHPMA-lac-PEG and different concentrations of HAMA (0-1% w/w) were cultured for 28 days in vitro and subsequently evaluated for the presence of cartilage-like matrix. Young's moduli were determined for hydrogels with the different HAMA concentrations. Additionally, hydrogel/PCL constructs with different internal architectures were co-printed and analyzed for their mechanical properties. The results of this study demonstrated a dose-dependent effect of HAMA concentration on cartilage matrix synthesis by chondrocytes. Glycosaminoglycan (GAG) and collagen type II content increased with intermediate HAMA concentrations (0.25-0.5%) compared to HAMA-free controls, while a relatively high HAMA concentration (1%) resulted in increased fibrocartilage formation. Young's moduli of generated hydrogel constructs ranged from 14 to 31 kPa and increased with increasing HAMA concentration. The pHPMA-lac-PEG hydrogels with 0.5% HAMA were found to be optimal for cartilage-like tissue formation. Therefore, this hydrogel system was co-printed with PCL to generate porous or solid constructs with different mesh sizes. Young's moduli of these composite constructs were in the range of native cartilage (3.5-4.6 MPa). Interestingly, the co-printing procedure influenced the mechanical properties of the final constructs. These findings are relevant for future bio-ink development, as they demonstrate the importance of selecting proper HAMA concentrations, as well as appropriate print settings and construct designs for optimal cartilage matrix deposition and final mechanical properties of constructs, respectively.

Published
2017

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