Formation and characterisation of a modifiable soft macro-porous hyaluronic acid cryogel platform

Abstract

A facile method for the synthesis of cell supportive, highly macro-porous hyaluronic acid (HA) hydrogels via cryogelation is presented. Unmodified HA was chemically cross-linked via EDC/NHS zero-length cross-linking at sub-zero temperatures to yield cryogels with high porosity and high pore interconnectivity. The physical properties of the HA cryogels including porosity, average pore size, elasticity and swelling properties were characterised as a function of cryogelation conditions and composition of the precursor solution. The HA cryogels swell extensively in water, with the average porosities observed being ~90% under all conditions explored. The morphology of the cryogels can be controlled, allowing scaffolds with an average pore size ranging from 18 ± 2 to 87 ± 5 μm to be formed. By varying the cross-linking degree and HA concentration, a wide range of bulk elastic properties can be achieved, ranging from ~1 kPa to above 10 kPa. Preliminary cell culture experiments, with NIH 3T3 and HEK 293 cell lines, performed on biochemically modified and unmodified gels show the cryogels support cell proliferation and cell interactions, illustrating the biomedical potential of the platform.

Cryogel-Integrated Biochip for Liver Tissue Engineering

“…In particular, increasing the amount of EDC had a much greater impact on scaffold stiffness and made it possible to mimic healthy or cirrhotic mechanical properties. Henderson et al observed the same trends with hyaluronic acid cryogels cross-linked with EDC by varying the Y from 1 to 10 kPa [56]. To obtain a Y corresponding to intermediate fibrosis states, other AAD:EDC ratios should be tested, rather than increasing the alginate concentration over 2% because of high viscosity solution.…”

Interactions between circulating nanoengineered polymer particles and extracellular matrix components in vitro

“…54 For example, multiple bioreactors could be assembled in series or in parallel, similar to the concept of using multiple, continuously perfused microchambers in microfluidic devices to create "organs-on-chips". 55,56 The tissue engineering scaffolds used here can support cell cultures, 35 and we have performed initial tests using 3D cell cultures inside the bioreactors. Although this introduces additional complexity (sterile conditions and incubation required) this could enable new types of bio-nano and particle-scaffold interactions to be investigated under physiologically relevant flow conditions.…”

“…Please do not adjust margins Please do not adjust margins cryogels (tissue engineering scaffolds described previously), 35,36 connect the bioreactors in-line to the circulation system, inject particles into the circulation, and study the particle interactions with the gels using flow cytometry and confocal laser scanning microscopy. We study and compare two types of soft polymer particlespoly(ethylene glycol) (PEG) and poly(methacrylic acid) (PMA) based particles-and show that material-dependent interactions affect particle removal from circulation in both the gel and scaffold systems.…”

“…Macroporous HA cryogels were prepared according to our previously published method by cryogelation with EDC-mediated zero-length crosslinking in custom-made glass and acrylic molds. 35 HA gels were labelled with Rhodamine B through rehydration. Matrigel matrix, used as a model ECM gel, was characterized based on a previously published method.…”

Combining mechanical foaming and thermally induced phase separation to generate chitosan scaffolds for soft tissue engineering

“…Scaffolds were left to incubate for 2 hours to allow cell attachment to the scaffold, following which a further 150 µl of DMEM was added to each well. This facilitates cell penetration and attachment in the scaffolds using capillary action to carry the suspension into the scaffold as it swells (51). Scaffolds loaded with cells were incubated for 3 days with the culture media being changed every 24 hours.…”