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- ItemMelt Electrowriting of Graded Porous Scaffolds to Mimic the Matrix Structure of the Human Trabecular Meshwork(Washington, DC : ACS Publ., 2022) Włodarczyk-Biegun, Małgorzata K.; Villiou, Maria; Koch, Marcus; Muth, Christina; Wang, Peixi; Ott, Jenna; del Campo, AranzazuThe permeability of the human trabecular meshwork (HTM) regulates eye pressure via a porosity gradient across its thickness modulated by stacked layers of matrix fibrils and cells. Changes in HTM porosity are associated with increases in intraocular pressure and the progress of diseases such as glaucoma. Engineered HTMs could help to understand the structure-function relation in natural tissues and lead to new regenerative solutions. Here, melt electrowriting (MEW) is explored as a biofabrication technique to produce fibrillar, porous scaffolds that mimic the multilayer, gradient structure of native HTM. Poly(caprolactone) constructs with a height of 125-500 μm and fiber diameters of 10-12 μm are printed. Scaffolds with a tensile modulus between 5.6 and 13 MPa and a static compression modulus in the range of 6-360 kPa are obtained by varying the scaffold design, that is, the density and orientation of the fibers and number of stacked layers. Primary HTM cells attach to the scaffolds, proliferate, and form a confluent layer within 8-14 days, depending on the scaffold design. High cell viability and cell morphology close to that in the native tissue are observed. The present work demonstrates the utility of MEW for reconstructing complex morphological features of natural tissues.
- ItemPrintability study of metal ion crosslinked PEG-catechol based inks(Cold Spring Harbor : Cold Spring Harbor Laboratory, 2019) Włodarczyk-Biegun, Malgorzata K.; Paez, Julieta I.; Villiou, Maria; Feng, Jun; del Campo, AranzazuInspired by reversible networks present in nature, we have explored the printability of catechol functionalized polyethylene glycol (PEG) based inks with metal-coordination crosslinking. Material formulations containing Al3+, Fe3+ or V3+ as crosslinking ions were tested. The printability and shape fidelity were dependent on the ink composition (metal ion type, pH, PEG molecular weight) and printing parameters (extrusion pressure and printing speed). The relaxation time, recovery rate and viscosity of the inks were analyzed in rheology studies and correlated with thermodynamic and ligand exchange kinetic constants of the dynamic bonds and the printing performance (i.e. shape fidelity of the printed structures). The relevance of the relaxation time and ligand exchange kinetics for printability was demonstrated. Cells seeded on the crosslinked materials were viable, indicating the potential of the formulations to be used as inks for cell encapsulation. The proposed dynamic ink design offers significant flexibility for 3D (bio)printing, and enables straightforward adjustment of the printable formulation to meet application-specific needs.
- ItemMelt Electrowriting of Scaffolds with a Porosity Gradient to Mimic the Matrix Structure of the Human Trabecular Meshwork(New York : Cold Spring Harbor Laboratory, 2022) Włodarczyk-Biegun, Małgorzata K.; Villiou, Maria; Koch, Marcus; Muth, Christina; Wang, Peixi; Ott, Jenna; del Campo, AranzazuThe permeability of the Human Trabecular Meshwork (HTM) regulates eye pressure via a porosity gradient across its thickness modulated by stacked layers of matrix fibrils and cells. Changes in HTM porosity are associated with increases in intraocular pressure and the progress of diseases like glaucoma. Engineered HTMs could help to understand the structure-function relation in natural tissues, and lead to new regenerative solutions. Here, melt electrowriting (MEW) is explored as a biofabrication technique to produce fibrillar, porous scaffolds that mimic the multilayer, gradient structure of native HTM. Poly(caprolactone) constructs with a height of 125-500 μm and fiber diameters of 10-12 μm are printed. Scaffolds with a tensile modulus between 5.6 and 13 MPa, and a static compression modulus in the range of 6-360 kPa are obtained by varying the scaffolds design, i.e., density and orientation of the fibers and number of stacked layers. Primary HTM cells attach to the scaffolds, proliferate, and form a confluent layer within 8-14 days, depending on the scaffold design. High cell viability and cell morphology close to that in the native tissue are observed. The present work demonstrates the utility of MEW to reconstruct complex morphological features of natural tissues.
- ItemPrinted Degradable Optical Waveguides for Guiding Light into Tissue(Weinheim : Wiley-VCH, 2020) Feng, Jun; Zheng, Yijun; Bhusari, Shardul; Villiou, Maria; Pearson, Samuel; del Campo, AránzazuOptogenetics and photonic technologies are changing the future of medicine. To implement light‐based therapies in the clinic, patient‐friendly devices that can deliver light inside the body while offering tunable properties and compatibility with soft tissues are needed. Here extrusion printing of degradable, hydrogel‐based optical waveguides with optical losses as low as 0.1 dB cm−1 at visible wavelengths is described. Core‐only and core‐cladding fibers are printed at room temperature from polyethylene glycol (PEG)‐based and PEG/Pluronic precursors, and cured by in situ photopolymerization. The obtained waveguides are flexible, with mechanical properties tunable within a tissue‐compatible range. Degradation times are also tunable by adjusting the molar mass of the diacrylate gel precursors, which are synthesized by linking PEG diacrylate (PEGDA) with varying proportions of DL‐dithiothreitol (DTT). The printed waveguides are used to activate photochemical and optogenetic processes in close‐to‐physiological environments. Light‐triggered migration of cells in a photoresponsive 3D hydrogel and drug release from an optogenetically‐engineered living material by delivering light across >5 cm of muscle tissue are demonstrated. These results quantify the in vitro performance, and reflect the potential of the printed degradable fibers for in vivo and clinical applications.