Cell culture has been a key tool in biomedical research for many years, enabling the development of therapeutic strategies through the study of cell behavior. Although traditional two-dimensional (2D) cell culture systems are valuable, they often fail to reproduce biological tissues' complex three-dimensional (3D) microenvironment. In recent years, the integration of 3D cell culture techniques and the use of microcarriers have emerged as revolutionary approaches, bridging the gap between in vitro and in vivo studies.
Related Products
The Limitations of 2D Cell Culture
In traditional 2D cell culture, cells are grown on a flat surface such as a Petri dish or culture flask. Although this method has contributed to numerous breakthroughs, it lacks spatial and physiological cues present in living organisms. Cells in 2D culture experience unnatural flat surfaces, altered cell-cell and cell-matrix interactions, and distinct nutrient gradients compared to their native environment. These limitations may bias results, which can impede translation to complex in vivo environments.
The Emergence of 3D Cell Culture
Recognizing the need for more physiologically relevant models, researchers turned to 3D cell culture systems. These techniques aim to recreate the cellular microenvironment by providing spatial organization, dynamic interactions, and nutrient gradients similar to those found in vivo. Spheroids, organoids, and scaffold-based cultures are examples of 3D cell culture methods that have gained popularity.
Fig 1 Conventional 3D models (A) Cell encapsulation model: Cells and alginate solution mixture are dispersed into a salt bath using a syringe for rapid polymerization to form microbeads. (B) Sandwich model: A monolayer of hepatocytes is sandwiched by two layers of an ECM protein such as collagen I or by Matrigel. (C) Salt-leaching hydrogel: Sacrificial salt porogens are initially mixed with the hydrogel for polymerization, then leached out to form a macroporous hydrogel. (Yao T, et al. 2021)
Spheroids are aggregates of cells that spontaneously form spherical structures in suspension. These structures improve interactions between cells and more closely resemble the structure of tissues. Organoids, on the other hand, are self-organizing 3D structures that mimic the complexity and function of organs. These systems provide a unique platform for studying organ development, disease modeling, and drug testing.
Although 3D cell culture methods have great advantages, they also present challenges in terms of scalability and reproducibility, and this is where microcarriers come into play, serving as important helpers in expanding and maintaining 3D cell cultures.
Microcarriers: Supporting 3D Cell Culture Expansion
Microcarriers are small, bead-like structures that provide a surface for cells to adhere and proliferate. Originally designed for the production of vaccines and therapeutic proteins in bioreactors, microcarriers have found a new role in 3D cell culture systems. By using these small carriers, cells can be expanded in a 3D manner, with flexibility and expansion possibilities.
Table 1 Technology for constructing 3D cell microcarriers. (Huang L, et al. 2020)
| Morphology |
Method |
Size (µm) |
| Non-porous microsphere |
Combining the emulsification method and biomimetic mineralization process |
70 |
| Fermentation by specific bacteria |
200–1000 |
| High-throughput double emulsion-based microfluidic approach |
100 |
| Through an acid dissolution/alkali precipitation approach. |
400 |
| Porous microsphere |
Micro-emulsification and thermally induced phase separation (TIPS) |
150 |
| Combination of the water-in-oil (W/O) emulsification process and the freeze-drying process |
100–500 |
| Microgel |
Using a microfluidic flow-focusing device |
100–160 |
| Combination of microfluidics technology and photopolymerization |
100 |
| Microfluidic approach |
50 |
| Multicomponent reactions |
40–80 |
| Droplet based microfluidic |
Micro-size |
In 3D cell culture using microcarriers, cells attach to the surface of these beads and form multi-layered structures. This method allows for the cultivation of a larger number of cells in a smaller space compared to traditional 2D cultures. Moreover, microcarriers provide a dynamic environment, allowing for the controlled movement of cells and nutrients, mimicking the fluid dynamics observed in vivo.
Applications of 3D Cell Culture and Microcarriers
The integration of 3D cell culture and microcarriers has broad implications across various fields of research and development. In drug discovery, these systems offer more predictive models for assessing drug efficacy and toxicity. 3D cell cultures, supported by microcarriers, provide a more accurate representation of in vivo conditions, improving the reliability of preclinical studies.
Cancer research has particularly benefited from 3D cell culture and microcarrier technology. Microcarriers can help spread cancer cells for high-throughput drug screening, thereby accelerating the discovery of potential therapeutics. Tumor spheroids and organoids allow researchers to study cancer progression, invasion, and treatment response in a more realistic environment.
In regenerative medicine, 3D cell culture techniques supported by microcarriers play a central role in tissue engineering. Microcarriers enable the production of large quantities of cells needed for tissue engineering applications, facilitating the transfer of these approaches from the laboratory to the clinical setting. Organoid creation and bioengineered tissue development hold promise for transplantation and personalized medicine.
References
- Yao T, Zhang Y, Lv M, Zang G, Ng SS, Chen X. Advances in 3D cell culture for liver preclinical studies. Acta Biochim Biophys Sin (Shanghai). 2021, 53(6):643-651.
- Huang L, Abdalla AME, Xiao L, Yang G. Biopolymer-Based Microcarriers for Three-Dimensional Cell Culture and Engineered Tissue Formation. Int J Mol Sci. 2020, 21(5):1895.
.
