Towards spatially-organized organs-on-chip: Photopatterning cell-laden thiol-ene and methacryloyl hydrogels in a microfluidic device

Advancements in the field of tissue engineering have led to the elucidation of physical and chemical characteristics of physiological basement membranes (BM) as specialized forms of the extracellular matrix. Efforts to recapitulate the intricate structure and biological composition of the BM have encountered various advancements due to its impact on cell fate, function, and regulation. More attention has been paid to synthesizing biocompatible and biofunctional fibrillar scaffolds that closely mimic the natural BM. Specific modifications in biomimetic BM have paved the way for the development of in vitro models like alveolar-capillary barrier, airway models, skin, blood-brain barrier, kidney barrier, and metastatic models, which can be used for personalized drug screening, understanding physiological and pathological pathways, and tissue implants. In this Review, we focus on the structure, composition, and functions of in vivo BM and the ongoing efforts to mimic it synthetically. Light has been shed on the advantages and limitations of various forms of biomimetic BM scaffolds including porous polymeric membranes, hydrogels, and electrospun membranes This Review further elaborates and justifies the significance of BM mimics in tissue engineering, in particular in the development of in vitro organ model systems.

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“… 245 , 246 Successful 3D structures in microfluidic chips have been achieved by photopatterning of cell-laden gelatin hydrogels ( Table 3 ). 247 …”

Section: Hydrogel As Bm Mimicsmentioning

confidence: 99%

Mimicking the Natural Basement Membrane for Advanced Tissue Engineering

et al. 2022

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“…Thiol-ene reaction owns many of the advantages of click chemistry, including robustness, simplicity, high selectivity, quantitative yielding, and insensitivity to oxygen or water . Owing to these attributes, there has been large interest in the last decade about the preparation of gelatin hydrogels introducing thiol reactivity toward electron-rich/electron-poor carbon–carbon double bonds. − Some reports have been published considering the research in which gelatin contains the thiol moiety, , although there is a wider variety in case gelatin contains the double-bond. − Thus, thiol-based click chemistry using norbornene-functionalized gelatin has been thoroughly described − and mostly applied in biofabrication. − As for the thiol-methacrylamide system, few studies have been found and only macromer concentration has been deeply investigated about its influence on mechanical properties and cell response . In those relevant studies, either the reaction involves a macromer also on the thiol sidegelatin, heparine, lignosulfonateor the thiol is added after the acrylate photopolymerization has taken place. − Other researchers have used in the same material crosslinking reactionsthiol-yne or dynamic covalent chemistryadditional to acrylate photopolymerization and thiol-ene reaction, which make interpretation of the structure–property relationships more challenging. , …”

Section: Introductionmentioning

confidence: 99%

“… 27 Owing to these attributes, there has been large interest in the last decade about the preparation of gelatin hydrogels introducing thiol reactivity toward electron-rich/electron-poor carbon–carbon double bonds. 28 − 30 Some reports have been published considering the research in which gelatin contains the thiol moiety, 31 , 32 although there is a wider variety in case gelatin contains the double-bond. 33 − 35 Thus, thiol-based click chemistry using norbornene-functionalized gelatin has been thoroughly described 36 − 39 and mostly applied in biofabrication.…”

Section: Introductionmentioning

confidence: 99%

Tuning of Mechanical Properties in Photopolymerizable Gelatin-Based Hydrogels for In Vitro Cell Culture Systems

Pamplona

González‐Lana

Romero

et al. 2023

ACS Appl. Polym. Mater.

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The mechanical microenvironment plays a crucial role in the evolution of colorectal cancer, a complex disease characterized by heterogeneous tumors with varying elasticity. Toward setting up distinct scenarios, herein, we describe the preparation and characterization of gelatin methacrylamide (GelMA)-based hydrogels via two different mechanisms: free-radical photopolymerization and photo-induced thiol-ene reaction. A precise stiffness modulation of covalently crosslinked scaffolds was achieved through the application of well-defined irradiation times while keeping the intensity constant. Besides, the incorporation of thiol chemistry strongly increased stiffness with low to moderate curing times. This wide range of finely tuned mechanical properties successfully covered from healthy tissue to colorectal cancer stages. Hydrogels prepared in phosphate-buffered saline or Dulbecco’s modified Eagle’s medium resulted in different mechanical and swelling properties, although a similar trend was observed for both conditions: thiol-ene systems exhibited higher stiffness and, at the same time, higher swelling capacity than free-radical photopolymerized networks. In terms of biological behavior, three of the substrates showed good cell proliferation rates according to the formation of a confluent monolayer of Caco-2 cells after 14 days of cell culture. Likewise, a characteristic apical-basal polarization of cells was observed for these three hydrogels. These results demonstrate the versatility of the presented platform of biomimetic materials as in vitro cell culture scaffolds.

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“…The inlet to the reservoir was placed higher than the outlet, passively restricting bubbles from entering the chip due to buoyancy. Since then, this device has been successfully implemented in PDMS by us and others [ 14 , 15 , 16 , 17 ]. The next step to increase its utility was to move away from manual assembly and adapt the design for more scalable manufacturing methods and materials.…”

Section: Introductionmentioning

confidence: 99%

A Scalable, Modular Degasser for Passive In-Line Removal of Bubbles from Biomicrofluidic Devices

et al. 2023

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Bubbles are a common cause of microfluidic malfunction, as they can perturb the fluid flow within the micro-sized features of a device. Since gas bubbles form easily within warm cell culture reagents, degassing is often necessary for biomicrofluidic systems. However, fabrication of a microscale degasser that can be used modularly with pre-existing chips may be cumbersome or challenging, especially for labs not equipped for traditional microfabrication, and current commercial options can be expensive. Here, we address the need for an affordable, accessible bubble trap that can be used in-line for continuous perfusion of organs-on-chip and other microfluidic cultures. We converted a previously described, manually fabricated PDMS degasser to allow scaled up, reproducible manufacturing by commercial machining or fused deposition modeling (FDM) 3D printing. After optimization, the machined and 3D printed degassers were found to be stable for >2 weeks under constant perfusion, without leaks. With a ~140 µL chamber volume, trapping capacity was extrapolated to allow for ~5–20 weeks of degassing depending on the rate of bubble formation. The degassers were biocompatible for use with cell culture, and they successfully prevented bubbles from reaching a downstream microfluidic device. Both degasser materials showed little to no leaching. The machined degasser did not absorb reagents, while the FDM printed degasser absorbed a small amount, and both maintained fluidic integrity from 1 µL/min to >1 mL/min of pressure-driven flow. Thus, these degassers can be fabricated in bulk and allow for long-term, efficient bubble removal in a simple microfluidic perfusion set-up.

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Towards spatially-organized organs-on-chip: Photopatterning cell-laden thiol-ene and methacryloyl hydrogels in a microfluidic device

Cited by 20 publications

References 74 publications

Mimicking the Natural Basement Membrane for Advanced Tissue Engineering

Mimicking the Natural Basement Membrane for Advanced Tissue Engineering

Tuning of Mechanical Properties in Photopolymerizable Gelatin-Based Hydrogels for In Vitro Cell Culture Systems

A Scalable, Modular Degasser for Passive In-Line Removal of Bubbles from Biomicrofluidic Devices

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