Cell migration and invasion play important roles in various physiological processes such as gastrulation, embryonic morphogenesis, development of the nervous system, and immune cell trafficking. Cells need to be able to change, interact with their environment, and reach their proper spatial orientation in a physiological setting to ideally execute their functions. Similarly, cell invasion is also crucial in the regulation of many pathological processes such as inflammation, cancer metastasis, cardiovascular disease, and preeclampsia. Recently, the utility of a spheroid invasion assay has increasingly become appreciated1,2. In this assay, cells are grown in a three-dimensional culture, in which their biological properties better mimic what would occur in a live tissue environment. For cancer study, spheroid culture allows better preservation of the interactions between cells and/or between cells and the extracellular matrix (ECM)3. The development of reliable, versatile, and easy-to-use spheroid invasion assays is thus very desirable.
In cancer invasion, there are three basic steps involved: (1) attachment of tumor cells to the extracellular matrix (ECM); (2) biodegradation of the ECM via proteolysis; and (3) cell migration through the compromised ECM. Each of these steps is important for tumor invasion to be successful, which means that the ECM must have components to promote attachment and biodegradation. Current animal-based ECM contains components from non-human sources that introduce unpredictability to 3D cell invasion study. Our synthetic, xeno-free functional hydrogel – VitroGel® system was developed to rectify this shortcoming. The state-of-the-art hydrogel system can closely mimic the physiological and functional properties of the native ECM and give an outstanding balance of biological complexity and operating ease to establish robust 3D cell models.
Tumor spheroids exhibit several characteristic physiological traits such as increased cell survival, hypoxic core, strong cell-cell interactions, etc. In this study, we establish a spheroid invasion assay by using U-87 MG glioblastoma cell line to study the tumor mobilization in a different hydrogel matrix. The cancer cell spheroids were created using the ultra-low attachment U-shaped plate (S-BIO PrimeSurface® 96U Plate, Cat# MS-9096UZ) before the invasion study. The spheroid invasion was established by adding the cell spheroid directly on top of a layer of hydrogel or encapsulating inside of the hydrogel matrix. In traditional animal-based ECM, the complexity of the hydrogel compositions makes it extremely difficult to understand how the hydrogel properties can affect cell mobility. However, the xeno-free VitroGel system can be easily manipulated in hydrogel strength, binding ligand, degradability, and supplement compositions, making it an excellent system to give an in-depth understanding of the relationship between the microenvironment and cell behaviors. To demonstrate that, we select two VitroGel hydrogels as examples in this study to show the effects functional binding ligands have on the invasion process: 1) VitroGel® Hydrogel Matrix (Cat# VHM01), a ready-to-use hydrogel of multi-functional ligands; and 2) VitroGel® 3D (Cat# TWG001), a high concentration hydrogel without binding ligand modification. The same concept can be explored in other types of VitroGel systems for different hydrogel properties. The protocol described here provides a reproducible method to form cancer spheroids and to observe invasion through an ECM. Our results demonstrate the VitroGel Hydrogel Matrix contains crucial biochemical and mechanical properties allowing for the replication of in vivo physiological processes and show the hydrogel’s potential to be used for high throughput screening pharmacological studies, cell culture of patient-derived culture models, and other types of translational research.
Source: The Well BioSciene
