3D Cell Culture

Three-dimensional (3D) cell culture offers biologically superior structures to study complex interactions that are impossible to achieve in 2D culture. 3D cell culture techniques reduce the gap between cell culture and the physiological environment. In vitro models based on 3D culture are closer to animal models in many aspects. 3D models imitate specific architecture and partially maintain the mechanical and biochemical cues of the original tissue. 3D cellular models have great potential in a variety of complex studies, such as drug discovery, pharmacological studies, cell physiology research, gene and protein expressions, cancer research, and tissue engineering.

Technologies of 3D Cell Culture

Various advanced 3D cell culture methods have been developed to meet the growing demand, but there is no single one that can meet all cell culture needs. 3D culture methods can be broadly categorized as scaffold-free and scaffold-based culture systems, the most commonly used among which are aggregate cultures, hydrogels, and solid scaffold-based technologies.

(A) Aggregate culture by ultra-low attachment surface

(B) Porous foam-solid scaffolds

(C) Hydrogel

International Journal of Molecular Sciences. 2021; 22(5):2491.

• Scaffold-based Technologies

The matrices/scaffolds make an important contribution to the artificial in vivo-like environment of 3D culture. Scaffolds are formed from natural and/or synthetic materials and can induce the particular morphology and physiological behavior of cultured cells. The choice of scaffolds depends on both the cell type and the nature of the study.

Natural biomaterials are usually based on various components of the extracellular matrix (ECM), such as collagen and hyaluronic acid, and include other naturally derived materials, such as silk, gelatin, and alginate. They are inherently biocompatible and bioactive and promote many cellular functions due to the presence of the myriad of endogenous factors.

Synthetic scaffolds with a definite chemical composition can achieve reproducibility, inertia, non-degradability, and tunable degradability that are not possible in naturally derived materials. Synthetic materials used in 3D scaffolds include biomaterials (such as polymers and titanium), ceramic-based materials (such as bioactive glasses), and self-assembled peptides.

Hydrogel technologies

3D culture methods based on scaffold can be broadly divided into hydrogels and solid scaffolds. Due to their ability to simulate the nature of most soft tissues, hydrogels are a highly attractive material for developing synthetic ECM analogs. Hydrogels are crosslinked networks of hydrophilic polymers. These reticulated structures of crosslinked polymer chains possess high water contents and facile transport of oxygen, nutrients, and waste. Furthermore, many hydrogels can be formed under mild, cytocompatible conditions and are easily modified to have cell adhesion ligands, desired viscoelasticity, and degradability. With a broad spectrum of mechanical and chemical properties, hydrogels are commonly used in models of branching morphogenesis, especially in vitro angiogenesis models, which have shown potential for vascular morphogenesis and preclinical studies.

LifeGel is a ready-to-use plate containing protein-base hydrogel for 3D cell culture. LifeGel products are available in 48-well and/or 96-well plate format with different standard cell media, depending on research requirements.

Solid scaffold-based technologies

Solid scaffolds are mainly porous foams or fibrous meshes that fabricated from synthetic polymers and naturally derived polymers. They facilitate cell proliferation and adhesion, as well as signaling activities between the cells in 3D cell culture. Porous foam-solid scaffolds with high porosity and a uniform interconnected structure are used for the 3D culture of many cell types. Fibrous scaffolds provide a large surface area for cell growth and a appropriate space for gas and nutrient exchange and cell infiltration. Fibrous scaffolds can imitate the structure of oriented and aligned tissues including skeletal muscle, central nervous system, and cardiac tissue, and induce stem cells to differentiate into the desired cell type.

Type I collagen

Type I collagen matrix is commonly used in 3D cell culture systems due to its ease of handling, low cost, and high flexibility for living cell manipulation. In addition, the pore size, ligand density and stiffness are varied by the changes in collagen concentration or the introduction of chemical cross-linked compounds, which changes the structural properties of the gel.

Amerigo Scientific offers medical or research grade type I collagen solutions for biological research and development, basic medical research, and food production. Medical-grade collagen production has been ISO-certified.

Laminins

The laminin protein family contains at least 16 different isoforms, most of which are currently available in pure form of recombinant proteins. Laminins affects cell adhesion, migration, phenotype maintenance, survival, and differentiation. Laminin-based cell culture and differentiation methods are widely used in the development of new human embryonic stem cells and in generating therapeutic human stem cell-derived cells for regenerative medicine.

Our highly pure recombinate laminin fragments can be used as culture substrates to promote cell survival, proliferation, and differentiation.

• Aggregate Culture and Cellular Spheroids

Scaffold-free systems primarily consist of the formation of multi-cellular aggregates, often referred to as spheroids. Cellular spheroids are simple 3D systems that take advantage of the natural tendency of many cell types to aggregate. In aggregates, cells form their own ECM components. By aggregating into spheres of several hundred microns, cells can contact with each other and re-establish specific microenvironments that allow them to express tissue-like phenotypes.

Spheroids from a broad range of cell types are formed by the hanging drop technique or by using low adherence substrates. In both cases, cells are unable to adhere to a surface and form clumps in suspension from single cultures or co-cultures (mono- or multicellular spheroids, respectively). Spheres as 3D systems can be directly applied to high-throughput screening and other biomedical studies. The simple spherical geometry closely resembles the structural and physiological environment of some tumor types, making it relatively easy to model dynamic processes, such as the growth and invasion of solid tumors.

Sphericalplate 5D (SP5D) is a patented 24-well plate that allows the generation of highly standardized cell spheroids by preventing cells attachment to the surface with a special nano-coating. Undisturbed communication between cells in the uniform sphere prevents false signals from causing unnecessary gene expression/differentiation.

• Microfluidic 3D Cell Culture

3D cell culture has been revolutionized by the integration of microfluidic technology. Microfluidic technology also known as Lab-on-a-chip (LOC) allows spatial control over fluids in micrometer-sized channels to improve the physiological relevance of 3D cell culture models. Microfluidic techniques are used for a wide range biomedical applications including drug discovery and development, cell research, genetic assays, protein studies, tissue engineering, and more. Significant features of microfluidic technology in 3D cell culture are as follows:

• Its microscale dimensions match many inherent microstructures and environments in vivo.
• Complex dynamic micro-scale environments that simulate in vivo environments can be achieved through microfluidic devices.
• Cell culture using microfluidic technology is very cost effective as only a small number of samples and reagents are required.
• Substrates of microfluidic devices are permeable to oxygen, which facilitate cell growth and proliferation.
• Microfluidic technology provides a versatile platform for 3D cell culture and subsequent cell analysis by integrating multiple steps including cell culture, cell sampling, fluid control, cell capture, cell lysis, mixing and detection into one device.

Applications of 3D Cell Culture

3D cell culture systems as tools for in vitro research are widely applied in differentiation studies, drug discovery, cancer research, gene and protein expression studies, and cellular physiological studies.

• Differentiation Studies

3D culture systems have been widely used in stem cell research and differentiation research and more complex and flexible scaffolds are developed for specific applications. In addition to providing useful insights for basic research, 3D cell culture for differentiation studies also make it possible to extend them to therapeutic applications. 3D cell culture systems also are used to obtain a supply of specifically differentiated cells. For example, pluripotent stem cells (PSCs) or embryonic stem cells (ESCs) are induced to differentiate into specific mature cells as an unlimited source of human cells. The prolonged survival of differentiated cells in 3D models is a major advantage in tissue engineering. These 3D cell models can be alternative for animal models in drug discovery, cancer biology, and regenerative medicine.

• Drug Discovery

3D cell culture is a simple but effective tool for drug discovery and toxicological and pharmacological studies. Compared with animal, 3D culture have great potential to improve the efficiency of drug screening and the ability to identify toxic or ineffective substances in the early stages of drug discovery. Moreover, 3D culture models as alternatives to animals avoid ethical concerns and greatly reduce the cost and complexity of experiments.

• Tumor Research

3D tumor spheroids have three layers of the central necrotic, inner quiescent and the outer proliferating, which closely reflect the microenvironment of solid tumors. Tumor cells grown in 3D culture conditions have many peculiar features that are parallel to tumors in vivo, especially in the early stages of tumor growth, before the tumor vascularization. 3D cell culture can be used in cancer research to study signaling pathways, expression and interactions with ECM components, cell communication, and cell proliferation.