Cell culture, the process of understanding growth and behavior of cells derived from multi-cellular eukaryotes, especially animal cells in a controlled environment in vitro is of great importance in cell biology research. Primarily there are two kinds of cell culture processes viz. adherent cell culture which requires surfaces coated with extracellular matrix component for growth and cell signaling, and non-adherent process which refers to culturing of the cell in suspension. Although most mammalian cells derived from solid tissues are adherent in nature but there are many applications where non-adherent mammalian culture is desirable such as with embryonic stem cells, neural stem cells, and macrophages. For such applications cells are usually grown as non-adherent cell clusters, known as spheroids. These spheroids have exciting applications, especially in cancer biology as drug screening tools. Other non-adherent culture systems include topographically patterned hydrophobic surfaces. These surfaces have anti-biofouling properties and very low surface area of contact and act as a platform for non-adherent mammalian cell culture. In a culture media non-adherent surfaces selectively allow growth of only specific cell types such as growth from cancer stem cells through sphere formation, as nonprogenitor bulk tumor do not survive suspension environments. Progress in these directions has the potential to create highly stable, chemically non-degradable non-adherent culture surfaces compatible with microfluidics and other high throughput technologies.
Non-adherent cell culture
A new non-adherent culture system, stable over long period of time has been developed using state-of-the art microfabrication techniques. Patterned silicon surfaces with desired topology were first generated using photolithography and deep reactive ion etching. Pattern transfer was done by pouring polydimethylsiloxane (PDMS) on the silicon mold and allowing it to cure followed by release to generate designed surface structure. Predefined surface geometries can be fabricated with varying pitch, features size, and shape for different hydrophobicity. The surface hydrophobicity was characterized by observing the contact angle of deionized water droplets. Various cell types were grown on the hydrophobic designs (circular, triangular, square, and honeycomb), but only the honeycomb hydrophobic design was capable of maintaining hydrophobicity to prevent cell adhesion. With the honeycomb hydrophobic surface, researchers have reported growth of cancer spheroids in suspension starting from single cancer stem cells both in macro-scale wells and in integrated microfluidic microwells. Thus, the key feature of the newly invented non-adherent cell culture surface lies in its compatibility with standard micro-fabrication technique and its ability to be integrated with well-developed microfluidic technology. Moreover it has the ability to form cancer spheroids from just single cells and does not have any non-adherent chemical coatings that make the surface highly stable and biocompatible.
- 3D cell culture
- Understanding cell to cell interactions
- Anti-biofouling applications
- Drug discovery
- Identification of cancer stem cells (CSCs)
- Hydrophobic surfaces
- Compatible with standard microfabrication technique.
- Can be integrated with high throughput microfluidic technology.
- Ability to form cancer spheroids from just single cells
- Do not use ono-adherent chemical coating