A Guide to Synthetic Hydrogels for 3D Cell Culture | Corning

Traditional cell culture is based on two-dimensional growth that creates flat monolayers. Although this method has been a foundation for in vitro studies, researchers are finding that scaffolding with a support matrix from various types of hydrogels yields better results, with cells showing more natural behavior.

This guide to synthetic hydrogels will answer questions on how to successfully grow cells in three dimensions and explain the difference between synthetic and biological 3D cell culture hydrogels.

What Are Hydrogels?

According to Elizabeth Abraham, Market Manager, 3D Cell Culture portfolio at Corning Life Sciences, hydrogels are biomaterials that absorb significant volumes of water and are, therefore, hydrophilic in nature. When used in cell culture, they self-assemble into a 3D structure that supports cell growth. With hydrogels, instead of cells growing on a surface as a monolayer, they aggregate and grow into 3D structures that can mimic tissue and organ anatomy.

Products for 3D cell culture hydrogels can be natural or synthetic. Examples of natural hydrogels include Corning® Matrigel® matrix, a natural extracellular matrix (ECM) product containing collagen and laminin harvested from Engelbreth-Holm-Swarm (EHS) mouse sarcoma cells. The ECM derivatives specifically encourage cell growth and assembly since they contain relevant surface signaling structures that interact with cell-surface receptors to influence behavior.

As a solubilized basement membrane preparation, Matrigel matrix encourages attachment and differentiation for a variety of adherent cells, including epithelial and tumor cell lines.

What Are Synthetic Hydrogels?

Biological products are naturally derived from cell lines to promote cell adhesion and growth. Synthetic versions are similar but are created and engineered de novo as single constituents or customized blends. Abraham describes them as "networks of covalently or ionically cross-linked homopolymers or co-polymers and polymerization of synthetic monomers that result in the hydrogel structure." They mimic natural hydrogels, but give researchers more control and flexibility since the components in the hydrogel are defined.

Alejandro Montoya, Senior Product Manager for Advanced Cell Culture at Corning Life Sciences explains, "The physiochemical properties used in the formulations of synthetic hydrogels will help determine their functional possibilities."

Abraham further expands on this customization potential: "Synthetic hydrogels can also be classified based on how they get cross-linked: physical, chemical, and enzymatic. In addition, the cross-linking can be time, temperature, pH, photopatterning, or interpenetrating polymer network dependent. The composition and the cross-linking used can impact many properties of these synthetic hydrogels, such as stiffness, elasticity, porosity, degradation, cell adhesion, and bioactivity."

How Do Hydrogels Work?

"Synthetic hydrogels provide a defined scaffold to help cells assemble into three-dimensional structures, which better recapitulate their physiological shape in vivo," says Hilary Sherman, a Senior Applications Scientist with Corning Life Sciences.

Instead of growing as flat 2D layers, the cells can assemble more naturally as if they were growing in vivo. There are differences in cell behavior depending on whether they grow in 2D or 3D culture conditions. For research, the 3D environment mimics natural conditions and supplies the sort of microenvironment that allows cells to signal more realistically.

With progress in cell culture portfolios, many products now support scaling up and automation, which benefits many applications, such as toxicology, drug discovery, and personalized cancer therapy.

What's Special About Synthetic 3D Cell Culture Hydrogels?

Biologic hydrogels, like Matrigel matrix, continue to be the gold standard ECM for cancer, stem cell, 3D cell, and organotypic culture and research.

Montoya notes, however, that synthetic hydrogels, such as Corning® Synthegel™ 3D matrix, offer a more defined and tunable environment. This environment is better at supporting the culture of cancer spheroids, especially the ones that don't naturally form spheroids in a scaffold-free environment. Synthetic formats are also important for the culture of human induced pluripotent stem cells (hiPSCs) and allow for 3D cell culture and scalability.

Customization is a major feature of synthetic hydrogels, in that they can be adjusted for different cells with precise information on the peptides, hydrogel rigidity, and growth factors present to better mimic their natural microenvironments.

"The Synthegel 3D matrix platform is chemically defined," states Montoya. "It also supports the culture of physiological cancer spheroids hiPSC 3D culture within a defined, tunable, and synthetic peptide matrix devoid of acidic or chilled conditions."

According to Montoya, some of the important features in Synthegel's 3D matrix include:

  • It is ideal for the formation and growth of physiologically relevant cancer spheroids
  • It allows 3D culture and passaging of hiPSCs in embedded and suspension conditions
  • The hiPSC Grow Mix supplement provides a complete culture environment for hiPSC 3D culture
  • It is a purified synthetic peptide in neutral pH
  • Matrix rigidity is tunable by altering the peptide concentration
  • Fast hydrogel formation (5 to 30 minutes)
  • It works with standard cell culture methodologies

Should You Use Biological or Synthetic Hydrogels?

Since there are two types of hydrogels available, what's the best way to decide which hydrogel to use?

As a guide to synthetic hydrogels, understanding composition and the role it plays in the design of your experiments is key, according to Sherman: "Some of the benefits of a synthetic hydrogel, like Synthegel 3D matrix, are that there are no unknown biological components contributing to the culture and that the composition of the hydrogel is consistent from lot to lot."

In other words, since biological hydrogels are derived from animal cells, they have certain variability, and they may contain a variety of growth factors. Unless built into the hydrogel formulation or added, synthetic hydrogels don't contain proteins or growth factors and, therefore, won't communicate with cells in the same way as biological hydrogels. For some applications, additional components might need to be added to replace the functional role components in biological hydrogels play.

The ability to customize or fine-tune a hydrogel depending on the cells to be cultured or their physical behavior can also be a deciding factor. Adjusting the characteristics of the support matrix can be managed by customizing the hydrogel blend.

According to Abraham, "Researchers can design scaffolds with pre-determined properties and desired bio-functionality based on the intended application."

For example, mesenchymal stem cells respond to mechanical forces, and their ability to differentiate depends on the applied forces. By altering the homopolymer blend, researchers can create a 3D matrix that supports cell behavior.

Synthetic hydrogels for 3D cell culture can be more versatile and controllable than biological hydrogels, and there may be a limitless number of combinations available to researchers seeking to work with the natural behavior of their cells.

As Abraham points out, "There are many recipes for synthetic hydrogels, and the winning combination will depend on how each hydrogel is designed to meet the properties of the cell type and application of interest."

Determining whether to use a synthetic or biological hydrogel will depend on your application and how it will interact with your experiment.

Learn more about Synthegel 3D matrix and how this solution can be utilized. For more information on the best surfaces for your application and cell type, download The Corning® Guide to Surface Selection by Cell Type.