Generation of Porous Poly(Ethylene Glycol) Hydrogels by Salt Leaching

Abstract

Poly(ethylene glycol) (PEG) hydrogels have been investigated for a number of applications in tissue engineering. The hydrogels can be designed to mimic tissues that have desired chemical and mechanical properties, but their physical structure can hinder cell migration, tissue invasion, and molecular transport. Synthesis of porous PEG hydrogels could improve transport, enhance cell behavior, and increase the surface area available for cell adhesion. Salt leaching methods have been used extensively to generate porous biomaterial scaffolds but have not previously been applied to hydrogels. In this article we describe a modification of traditional salt leaching techniques for application to hydrogels. Salt-saturated polymer precursor solutions are prepared, and salt crystals of a defined size are added before polymerization. The salt crystals are then leached out, resulting in porous hydrogels. Examples are provided for application of this technique to PEG hydrogels. Porous PEG hydrogels were generated with pore sizes ranging from 15 to 86 microm and porosities from 30% to 75%. Porous hydrogels that were incorporated with a cell adhesion peptide supported cell adhesion with morphology varying with pore size. The simple, reproducible technique described here could be used to generate porous hydrogels with controlled pore sizes for applications in tissue engineering.

In situ vascularization of injectable fibrin/poly(ethylene glycol) hydrogels by human amniotic fluid‐derived stem cells

“…[25] A subcutaneous model was chosen for in vivo evaluation in order to facilitate in situ polymerization of fibrin-based hydrogels and minimize the trauma associated with alternative methods of vascular assessment, such as those that create a pocket between the fascia and muscle. [47] [49] and the driving factor is hypothesized to be the hydrolysis half life of the reactive ester group on this PEG variant, which ranges from 10 minutes to 4 hours. [38,53] Control hydrogels without cells injected in this murine model showed host cell infiltration on the order of 20-25 µm/day, which is in agreement with reported values of PEG/fibrin hydrogels with similar fibrinogen concentrations.…”

Three-Dimensional Scaffolds for Tissue Engineering Applications: Role of Porosity and Pore Size

“…[3][4][5] Threedimensional scaffolds are typically porous, biocompatible and biodegradable materials that serve to provide suitable microenvironments, that is, mechanical support, physical, and biochemical stimuli for optimal cell growth and function ( Fig. 1).…”

Fabrication of Cell-Laden Macroporous Biodegradable Hydrogels with Tunable Porosities and Pore Sizes

“…4,6,7 A number of fabrication techniques have been developed to generate pores within hydrogels for tissue engineering applications, including electrospinning, 8,9 gas foaming, [10][11][12][13] freeze-thaw, 14,15 phase separation, [16][17][18][19] and salt leaching. [20][21][22] However, the majority of these techniques for generating macroporous hydrogels often involve cytotoxic procedures or chemicals that undermine a key advantage hydrogels have over other traditional tissue engineering scaffolds: the ability to encapsulate viable cells with a homogeneous distribution within the 3D scaffold during fabrication. 4,23 Subsequent cell seeding in such scaffolds may lead to low seeding efficiency and a heterogeneous cell distribution, particularly without proper pore interconnectivity.…”