In the laboratory culture of cells, it is important to have the appropriate cell surface that the cells can attach, grow, and thrive. This is where cell culture protein surface coating comes in very handy. Such coatings resemble the natural environment of the cells, enhancing their attachment, growth and activity. Now we are going to examine the most popular protein coatings that assist in adhesion and adherence of cells in cell culture.
Collagen: The Classic Supporter
One of the most popular cell culture surface protein coating is Collagen, more so the Type I and IV. It offers a powerful framework onto which numerous cell types, such as fibroblasts, epithelial cells and hepatocytes can readily adhere to and proliferate. Collagen forms a natural-like environment since it is a significant constituent of the extracellular matrix (ECM) within the body as it is a prominent constituent of the tissue structure and cell signaling.
Laminin: Essential for Stem Cells and Neurons
Another notable protein coating is laminin, especially when it comes to cultures containing neural cells and induced pluripotent stem cells (iPSCs). It aids in the sustenance and distinction of these delicate cells through the development of neuron and glial cells. The experiments in which it is important to retain the pluripotency of the stem cells or enable the growth of nerve cells tend to use laminin.
Fibronectin and Vitronectin: Promoters of Adhesion
Fibronectin and vitronectin are ECM proteins which offer special binding sites known as integrin-binding domains. They are important in the cell adhesion, survival, and spreading of the cells particularly when they are cultured in serum free or chemically defined media where the natural adhesion factors are absent. They have been applied with mesenchymal stem cells (MSCs) and iPSCs to enhance healthy development.
Poly-L-Lysine and Poly-Ornithine: Synthetic Helpers
Not all coatings are “true” proteins. Synthetic cover-slips including PLL and poly-ornithine create a positively charged surface and attract negatively charged cell membranes. These coatings enhance the adherence of neurons, glial cells and some challenging-to-culture cell lines. They do so by augmenting electrostatic interactions, and are often used independently or grafted to biological proteins for improved cell adhesion.
Gelatin: A Versatile Protein Coating
Gelatin, derived from collagen, is also popular in cell culture coatings. It provides sites for cell attachment and can promote cell growth and differentiation. It offers a cost-effective alternative to pure collagen while still supporting cell adhesion effectively.
Advanced Coatings: ECM Mixtures and Surface Treatments
In addition to monoprotein coatings, mixtures including Matrigel (a complex ECM-based product) provide a more cellular native environment since they contain multiple proteins and growth factors. Surface modifications such as Corning® CellBIND® leverage plasma technology to increase surface hydrophilicity and enable cell attachment without the use of biological coatings. These methods are designed to address challenging or fragile cells and for process consistency.
Why Are Protein Coatings So Important?
Many standard cell lines grow well on typical tissue culture-treated plastic surfaces. However, primary cells, stem cells, and specialized cells often require protein coatings to maintain their natural phenotype and function. These coatings help cells stick better, grow faster, and behave more like they do in the body.
Matching Coatings to Cell Types
- Fibroblasts and epithelial cells: Prefer collagen-coated surfaces.
- Neurons and neural progenitors: Grow best on laminin or poly-L-lysine.
- Stem cells (iPSCs, MSCs): Require fibronectin, vitronectin, or laminin coatings.
- Hard-to-attach cells: Benefit from synthetic coatings like poly-ornithine.
How Are Coatings Applied?
Protein coats are commonly applied to a plastic tissue treated surface by incubating the plastic surface in a solution of protein which is then absorbed to the surface. Next, the superfluous solution is aspirated off prior to seeding of cells. Some coatings benefit from optimization of the dilution for best results, since insufficient or excessive quantities of protein affect cell attachment.
Emerging Trends: Functionalized and Synthetic Surfaces
With continual research, more advanced coatings are being developed. These include surfaces functionalized with specific peptide sequences or bioactive molecules designed to enhance particular cellular responses. Synthetic polymers like cyclic olefin polymer (COP) are being functionalized with protein coatings through novel techniques such as cold plasma deposition, improving attachment on materials that are traditionally challenging for cell culture.
