Cell-Degradable (CD) Hydrogels Support Cell Spreading and Migration
A hydrogel that allows cells to spread and migrate within their in vitro environment is a better mimic of the native in vivo tissue environment
The 3-D Life platform provides the highest flexibility in designing biomimetic hydrogels: hydrogel stiffness, attachment of adhesion peptides, matrix metalloproteinase degradability, and protease-free gel dissolution for cell recovery can all be chosen independently from one another.
3-D Life Hydrogels consist of a dense network of polymers with small pores at an estimated size of only several nanometers. If cells are supposed to spread and migrate within the gel, the dense network of polymers must be broken up by the cells. With 3-D Life PVA or dextran based hydrogels, you have the option of using the non-cell-degradable PEG-Link crosslinker, or you can choose to use the CD-Link crosslinker.
3-D Life CD-Link contains a matrix metalloproteinase (MMP)-cleavable peptide sequence (Pro-Leu-Gly-Leu-Trp-Ala), which is cleaved by a broad range of MMPs including MMP1, MMP3, MMP7 and MMP9. It allows cells to locally degrade the polymer network, if they produce the indicated MMPs. As a consequence, the hydrogel network locally loosens up and cells can spread within the gel (illustrated in Fig. 1 below).
Figure 1: Schematic drawing of cells growing in 3-D Life PVA Hydrogel crosslinked with either 3-D Life PEG-Link (left) or 3-D Life CD-Link (right).
Cell spreading requires MMP cleavage and cell adhesion sites
Example application: Fibroblast Spreading in Cell-Degradable 3-D Life Hydrogels
In this example, 3T3 fibroblasts were grown in PVA hydrogel that was either crosslinked with the undegradable crosslinker 3-D Life PEG-Link or the MMP-cleavable 3-D Life CD-Link (Fig. 2). Cells grown in hydrogels with CD-Link spread whereas cells grown in gels crosslinked with PEG-Link stay round in tightly packed aggregates. Spreading of fibroblasts in 3-D Life Hydrogels does also require the presence of adhesion sites, e.g. the 3-D Life RGD Peptide. RGD sequences are motifs on extracellular matrix (ECM) proteins promoting adhesion to cellular integrin receptors. Without adhesion sites, cells remain in tightly packed aggregates (not shown).
Figure 2: Confocal laser scanning microscopy of 3T3 fibroblasts cultured 14 days in 3-D Life PVA-Hydrogel modified with RGD peptide and crosslinked with either 3-D Life PEG-Link (left) or 3-D Life CD-Link (right). Pictures show collapsed stacks of confocal frames representing a height of 300 µm of the gel. Red: nuclei; green: actin cytoskeleton. Scale bar: 200 µm.
Acknowledgement
The content above has been adapted from Cellendes GmbH 3-D Life Application Note 2: Fibroblast Spreading in Cell-Degradable 3-D Life Hydrogels.
Ilex Life Sciences LLC is an official distributor of Cellendes GmbH 3-D Life hydrogel products. To learn more about 3-D Life hydrogels, please visit 3-D Life Biomimetic Hydrogels.