Macromolecular crowding transforms regenerative medicine by enabling the accelerated development of functional and truly three-dimensional tissue moduli
De Pieri, Andrea
De Pieri, Andrea
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2020-11-04
Type
Thesis
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Abstract
Scaffold-free in vitro organogenesis exploits the innate ability of cells to synthesise and deposit their own extracellular matrix to fabricate tissue-like assemblies. Unfortunately, traditional cell-assembled tissue engineered concepts require prolonged ex vivo culture periods of very high cell numbers for the development of a borderline three-dimensional implantable device, which are associated with phenotypic drift and high manufacturing costs, thus, hindering their clinical translation and commercialisation. Macromolecular crowding, a biophysical phenomenon based on the principle of excluded-volume effect, dramatically accelerates and increases extracellular matrix deposition during in vitro culture. However, the optimal macromolecular crowder is still elusive and the therapeutic potential of macromolecular crowding has yet to be evaluated. With respect to the optimal macromolecular crowder, the biophysical properties of various concentrations of different seaweed in origin sulphated polysaccharides (carrageenan, fucoidan, galactofucan, arabinogalactan, ulvan) and their effect on human adipose derived stem cell cultures were assessed. Carrageenan, possibly due to its high sulphation degree, exhibited the highest negative charge values. No correlation was observed between the different concentrations of the crowders and charge, polydispersity index, hydrodynamic radius and fraction volume occupancy across all crowders. None of the crowders, but arabinogalactan, negatively affected cell viability. Carrageenan, fucoidan, galactofucan and ulvan increased extracellular matrix (especially collagen type I and collagen type V) deposition. Carrageenan induced the highest osteogenic effect and galactofucan and fucoidan demonstrated the highest chondrogenic effect. With respect to therapeutic effect, carrageenan (50 μg/ml) was used as macromolecular crowding agent to produce extracellular matrix-rich tissue equivalents, using only 50,000 human adipose derived stem cells per cm2 on an 85:15 poly-N-isopropylacrylamide-N-tert-butylacrylamide temperature-responsive electrospun scaffold. The combination of macromolecular crowding and the temperature-responsive electrospun scaffold enabled the accelerated (10 days) development of a truly three-dimensional (338.1 ± 42.9 μm) scaffold-free tissue equivalent that promoted fast wound healing and induced neotissue formation composed of mature collagen fibres. Collectively, data obtained highlight the potential of macromolecular crowding to transform regenerative medicine by enabling the accelerated development of functional and truly three-dimensional tissue modulus and pave the path for a new era in scaffold-free tissue engineering.
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NUI Galway
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Attribution-NonCommercial-NoDerivs 3.0 Ireland