matrix gel mixture injection into mouse for matrix gel plug assay

Simplifying Angiogenesis Studies with a Modified Matrix Gel Plug Assay

Angiogenesis, the process of formation of neo-vessels from pre-existing vessels, plays a critical role in many physiological and pathological processes, such as embryonic development, wound healing, atherosclerosis, tumor development, etc.1,2,3,4,5. This dynamic process involves several steps, including the degradation of the matrix, vascular cell proliferation, migration and self-organization to form tubular structures and the stabilization of the neo-vessels6. Promoting angiogenesis has been demonstrated to be critical in the treatment of myocardial infarction, stroke and other kinds of ischemic diseases7 while inhibiting angiogenesis has been considered a promising strategy in the treatment of cancers8 and rheumatoid diseases9. Angiogenesis has been considered an organizing principle for drug discovery10. Thus, the construction of a reliable and convenient method to assess the extent of angiogenesis is critical for mechanical research or drug discovery in angiogenesis-dependent diseases.
Several in vitro and in vivo models have been developed to evaluate angiogenesis11. Among these, two-dimensional (2-D) models, like matrix gel tube formation assay12, cannot form functional tubular structures. The animal models, such as the hind limb ischemia model13,14, can reproduce the angiogenesis process but are complex and require a laser speckle blood flow imaging system. 3D models of vascular morphogenesis, like matrix gel plug assay, provide a simple platform that can mimic the process of angiogenesis in vivo15, but the detection of angiogenesis requires immunohistochemistry or immunofluorescence staining16,17,18, which are variable and poorly visualized.
Here, we describe a protocol for a modified matrix gel plug assay where vascular cells were mixed with matrix gel and subcutaneously injected into the back of mice to form a plug. In the plug, vascular cells need to degrade the matrix, proliferate, migrate, and self-organize to finally form functional vessels with blood flow in the internal environment. Thereafter, fluorescent-labeled dextran is injected via the tail vein, to flow through the plug, and the label is visualized to indicate neo-vessels. The content of angiogenesis can be quantitatively evaluated by the length of the vessels. This method can form functional vessels that cannot be produced in 2-D angiogenesis models12, and does not need complex stain process as in ordinary matrix gel plug assay11. It also does not require expensive specific instruments like laser speckle blood flow imaging system in hind limb ischemia model13,14,19. This method is versatile, low-cost, quantifiable, and easy to perform, and can be used to determine the pro- or anti-angiogenic capability of drugs or be used in mechanical research involved in angiogenesis.

Author Spotlight: Investigating Angiogenesis and Vessel Permeability Through a Modified Matrix Gel Plug Assay

Modified In Vivo Matrix Gel Plug Assay for Angiogenesis Studies

Our research deals with angiogenesis, the process of formation of new vessels from preexisting vessels. It plays a critical role in many physiological and pathological processes, such as embryonic development or curing atherosclerosis, tumor development, etc. The construction of a reliable model to evaluate the extent of angiogenesis is critical for myocardial research or the discovery of medicines for angiogenesis-depend diseases.However, most of the existing models are complex, expensive, and require specialized equipment. Here, we present a modified matrix gel plug assay that can be used to investigate angiogenesis and vessel permeability without staining in a simple, more intuitive, as well as efficient manner.

Matrix Gel Mixture Injection into Mouse for Matrix Gel Plug Assay

To begin, place the 30 gauge one milliliter insulin syringes in a four degrees Celsius refrigerator for cooling. Keep the freshly prepared matrix gel mix containing vascular cells on ice until the mouse is ready for the injection. Next, place the properly anesthetized mouse on the operating board in a prone position and secure its limbs onto the board using tape.Load a pre cooled insulin syringe with 300 microliters of the matrix gel mixture, avoiding the formation of bubbles. Disinfect the skin on the back of the mouse using 75%alcohol pads, then subcutaneously inject 300 microliters of the matrix gel mixture in the syringe into one side of the animal's back. Gently remove the needle from the injection site to prevent any leakage of the gel mixture.Ensure the formation of a small hump at the injection site. Position the mouse on a heating pad for two minutes to allow the matrix gel mixture to coagulate and form a plug. Repeat the demonstrated steps to create a plug on the other side of the mouse's back.Mark the edges of the hump using a marker pen. House the animal in a specific pathogen free experimental animal laboratory at 20 to 24 degrees with 12 hour light and 12 hour dark cycles for seven days.

Research

JoVE Journal

Biology

Several models have been developed to investigate angiogenesis in vivo. However, most of these models are complex and expensive, require specialized ...

Preparing Vascular Cells for In Vivo Matrix Gel Plug Assay

Preparing Matrix Gel with Vascular Cells for In Vivo Matrix Gel Plug Assay

Dextran-FITC Injection and Matrix Gel Plug Collection from Mouse for Matrix Gel Plug Assay