Cell migration is the ability of cells to move within tissues and traverse biological barriers. It is a fundamental process that occurs during embryonic development, wound healing, immune responses and other biological events. During migration, cells extend protrusions in the direction of movement, establish anchorage points through adhesion receptors, and generate forces to pull the cell body forward. Various cell types exhibit different migratory behaviors depending on their function. For example, immune cells migrate rapidly to sites of infection or injury, while endothelial cells crawl slowly during angiogenesis. Precisely regulated migration underlies many physiological processes, while aberrant migration contributes to diseases like cancer metastasis.
In Vitro Cell Migration And Cell Invasion Assay
To study Cell Migration And Cell Invasion Assay mechanisms and effects of drugs or environmental cues, several in vitro assays have been developed. Some common migration assays are:
Scratch (Wound Healing) Assay: In this assay, a scratch or cell-free area is created uniformly in a confluent monolayer culture using a pipette tip or other instrument. Cells are then monitored as they migrate into the vacant area over time. The rate of closure of the scratch area provides a quantitative measure of migration. Phase contrast imaging allows tracking of leading edges.
Boyden Chamber (Transwell) Assay: Cells are seeded on top of a porous membrane insert that separates the insert from a lower well. A chemoattractant (e.g. growth factor) is added to the lower well to induce directed migration. After incubation, cells that have migrated to the bottom side of the insert membrane are fixed, stained and counted. This assay mimics in vivo processes like extravasation.
Invasion Assays
While migration involves movement of cells on tissue culture surfaces, invasion refers to migration across basement membrane or extracellular matrix (ECM) barriers. Specific assays evaluate invasive potential of cells.
Invasion Chamber Assay: Similar to Boyden chamber but the porous membrane is coated with reconstituted basement membrane extracts like Matrigel. Cells that traverse the barrier and migrate to the lower side are quantified. This assay models key steps of metastasis – local invasion followed by migration.
Spheroid Invasion Assay: Cells are cultured as spherical aggregates/spheroids embedded in matrix layers like collagen or Matrigel. Invasion is measured as migratory distance or number of cells emerging from the spheroid boundary over time. This 3D culture format models avascular tumor growth and stromal invasion better than monolayer methods.
Monitoring Cell Migration And Invasion
To visualize and quantify cell migration behaviors, several microscopy-based techniques are useful:
– Time-Lapse Microscopy: Cells can be imaged continuously on a microscope stage at set intervals. Migration tracks and velocities are extracted from series of phase images using tracking software.
– Live-Cell Imaging: Fluorescent proteins or dyes are used to label specific structures in living cells. Movement dynamics of leading edges, protrusions, focal adhesions etc. are studied with fluorescence or confocal microscopy.
– Wound Healing Imaging: Automated systems maintain optimal culture conditions and acquire images automatically over longer durations to document wound closure kinetics.
– Invasion Imaging: Fluorescently labeled cells are tracked as they invade Matrigel or collagen layers sandwiched between glass surfaces for z-stack imaging. 3D models provide useful invasion metrics.
Factors Regulating Migration And Invasion
Cell migration is controlled by integrated signaling networks that dictate cytoskeletal remodeling, adhesion dynamics and membrane protrusions. Altered expression or activity of key molecules in these pathways often enhances migratory and invasive behavior of cancer cells. Some of the main regulatory factors include:
– Rho Family Gtpases (Rhoa, Rac1, Cdc42): Coordinate actin cytoskeleton and focal adhesion changes essential for protrusions, contractility and rear detachment.
– Integrins: Transmembrane receptors that bind ECM proteins and couple intracellular signaling to extracellular matrix. Certain integrins promote mesenchymal or amoeboid invasion.
– Matrix Metalloproteinases (MMPs): Degrade ECM and allow local invasion. Specific MMPs associated with cancer progression and metastasis.
– Angiogenic growth factors: Like VEGF, FGF induce migratory responses in endothelial cells during angiogenesis. Also stimulate tumor cell migration and pre-metastatic niche formation.
– EMT inducing factors: Snail, Twist, ZEB1 activate epithelial-mesenchymal transition (EMT) – a migratory and invasive phenotype in carcinoma cells.
Cell migration and invasion play key roles in normal tissue homeostasis as well as pathologies. The ability to mimic these processes in vitro through defined assays has enabled improved mechanistic understanding and identification of targets to modulate migration in disease settings. Further refinement of 3D culture models will advance the field.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
About Author – Vaagisha Singh
Vaagisha brings over three years of expertise as a content editor in the market research domain. Originally a creative writer, she discovered her passion for editing, combining her flair for writing with a meticulous eye for detail. Her ability to craft and refine compelling content makes her an invaluable asset in delivering polished and engaging write-ups. LinkedIn