The Matrigel Invasion Assay is a laboratory method used to investigate how cells move through a barrier, simulating conditions found within the body. This technique helps scientists understand the mechanisms behind various biological processes, particularly those involving cell movement through tissues. It provides a controlled environment to study cellular behavior. The assay offers insights into how cells interact with their surroundings and overcome physical obstacles.
Understanding Cellular Invasion
Cellular invasion is a specific type of cell movement where cells actively penetrate and navigate through surrounding tissues. This process differs from simple cell migration, which primarily involves directed movement across a surface in response to stimuli. Invasion, in contrast, requires cells to degrade and remodel the extracellular matrix (ECM), a complex network of proteins and carbohydrates that provides structural support and acts as a natural barrier between cells and tissues.
Understanding cellular invasion is particularly important in the context of diseases like cancer. In cancer progression, cells break away from a primary tumor and invade surrounding healthy tissues, a process known as metastasis. These invasive cancer cells must degrade the ECM and penetrate physical barriers to enter the bloodstream or lymphatic system, allowing them to spread to distant sites and form new tumors. The ECM acts as a significant obstacle that cells must overcome during invasion.
How the Matrigel Invasion Assay Works
The Matrigel invasion assay utilizes a specialized laboratory tool called a Transwell insert, which features a porous polycarbonate membrane. The upper surface of this membrane is coated with Matrigel, a solubilized basement membrane extract derived from a mouse tumor. Matrigel primarily consists of proteins such as laminin, collagen IV, and entactin, along with growth factors and other components found in natural basement membranes.
This Matrigel layer acts as an artificial extracellular matrix, mimicking the natural tissue barrier that cells encounter in the body. Cells intended for study are placed in a serum-free medium on top of the Matrigel-coated membrane in the upper chamber of the Transwell insert. A chemoattractant, a substance that chemically attracts cells, is then placed in the lower chamber beneath the membrane. Common chemoattractants include fetal bovine serum (FBS) or specific growth factors.
The principle of the assay relies on the ability of invasive cells to degrade the Matrigel layer and pass through the membrane’s pores, moving towards the chemoattractant in the lower chamber. Non-invasive cells, lacking the necessary enzymes or migratory capabilities, are unable to penetrate the Matrigel barrier. After an incubation period, cells that have successfully invaded and reached the lower side of the membrane are fixed and stained, often using dyes like crystal violet. These stained cells are then counted to quantify the extent of invasion.
Key Applications of the Assay
The Matrigel Invasion Assay is widely used in various areas of biological research, especially in cancer studies. It helps scientists assess the metastatic potential of tumor cells, providing insights into how cancer cells spread within the body. This assay also serves as a tool for screening anti-cancer drugs that aim to inhibit cell invasion.
Beyond cancer research, the assay contributes to understanding other biological processes involving cell movement. It is applied to study the migration of immune cells, which navigate through tissues to reach sites of infection or inflammation. The assay also finds utility in tissue regeneration studies, where understanding how cells invade and integrate into new environments is important for developing regenerative therapies. It assists in analyzing the functional role of specific genes in cell invasion and can be adapted for drug screening to identify anti-metastatic compounds.