Cellularized Cellular Solids via Freeze‐Casting

Abstract

The elaboration of metabolically active cell-containing materials is a decisive step toward the successful application of cell based technologies. The present work unveils a new process allowing to simultaneously encapsulate living cells and shaping cell-containing materials into solid-state macroporous foams with precisely controlled morphology. Our strategy is based on freeze casting, an ice templating materials processing technique that has recently emerged for the structuration of colloids into macroporous materials. Our results indicate that it is possible to combine the precise structuration of the materials with cellular metabolic activity for the model organism Saccharomyces cerevisiae.

Unveiling cells’ local environment during cryopreservation by correlativein situspatial and thermal analyses

“…Another particularly important aspect is the fate of cells during their interaction with the freezing front. As reported previously 20 , yeast cells are observed covered in a polysaccharide envelope, regardless of the ice front velocity used in the directional freezing ( Figure S3). However, to establish a quantitative relationship between cell viability and ice front velocity we should ensure that the ratio of cells that end up within the interstitial space defined by ice crystals (i.e.…”

“…The minimum Feret diameter of the macroporous alginate structures observed under SEM after freeze drying, displayed in the supplementary information ( Figure S6) and the periodic distances obtained under the confocal microscope ( Figure S7) are relevant measures to describe the wall-to-wall distance of the lamellar pores generated by the growth of ice crystals. The inverse scaling between ice crystals size and ice front velocity observed here is a common behavior described for ice-templating of a variety of systems ranging from biopolymers 20,42 to ceramic slurries 43,44 . While the morphological feature may seem of little relevance to cell viability, the size and distribution of ice crystals within the sample may have significant impact during thawing of the samples, notably on their likelihood to endure recrystallization, a key aspect in cell injury.…”

Unveiling Cells’ Local Environment during Cryopreservation by Correlative In Situ Spatial and Thermal Analyses

“…41 Figure S6) and the periodic distances obtained under the confocal microscope ( Figure S7) are relevant measures to describe the wall-to-wall distance of the lamellar pores generated by the growth of ice crystals. The inverse scaling between ice crystals size and ice front velocity observed here is a common behavior described for ice-templating of a variety of systems ranging from biopolymers 20,42 to ceramic slurries 43,44 . (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.…”

“…To circumvent these issues AFP mimics such as Poly(vinyl alcohol) (PVA) have been used for animal cell 17 and bacteria 15 cryopreservation as biocompatible alternatives endued with IRI properties. Complex carbohydrates such as hydroxyethyl starch (HES) 18,19 , alginate [20][21][22] or synthetic polyampholytes 23 have been adopted in the field of cell cryopreservation either with other pCPAs or alone. More radical solutions have also been proposed such as the use of metal-organic frameworks, 24 armors around cells to prevent damage by ice crystals or hydroxyapatite nanoparticles, 13 Here we address that question by using a very simple freezing medium, sodium alginate solution in water, to focus on the cellular environment during the freezing process.…”

Colloidal systems toward 3D cell culture scaffolds

“…The authors additionallydemonstrated that ISISA is a versatile and biocompatible technique allowing the incorporation of enzymes or liposomes into the hierarchical materials[70,76]. Another major advantage of unidirectional freezing is that it offers the possibility to encapsulate living cells within the 3D scaffolds[77]. Scaffolds with pore sizes ranging from 25 to 90 µm and 85% porosity were achieved by varying the freezing rate.…”