The Advanced Solutions team in Manchester, NH, lead by Dr. Jay Hoying, have been studying the use of Angiomics™ microvessels into Matrigel-based models and assays to improve the biology in a model. Here are their results:
Matrigel is a solubilized basement membrane matrix derived from EHS mouse sarcomas that is rich in growth factors and signaling molecules. It is commonly used in a variety of applications in biomedical research, acting as a platform for complex signaling and as a support for cells and tissues. For example, it is often used in tumor spheroid models to support cellular hyperproliferation, differentiation, and invasion, key features of tumors (Benton, et al., Adv Drug Deliv Rev, 2014. 79-80: p. 3-18). Matrigel stimulates endothelial adhesion and migration, enhance protease activity, and enables cord formation. As such, it is frequently used in endothelial cell assays serving as simplified models for studying angiogenic activity (Arnaoutova and Kleinman, Nat Protoc, 2010. 5(4): p. 628-35). Matrigel can be used by itself, or combined with collagen, to coat cell culture plates or used as a 3D matrix to directly encapsulate cells or spheroids in 3D culture.
Angiomics™ Microvessels and Matrigel
Vascularization is a key for the survival and function of nearly every tissue type and is important to include in tissue models. The Angiomics™ microvessel system is a tissue vascularization system utilizing intact fragments of human adipose microvasculatures. These microvessels, when embedded in extracellular matrix, spontaneously sprout, grow, and form a robust neovascular network via bona fide sprouting angiogenesis. As the uses for microvessels continue to expand, we evaluated the angiogenic potential of the Angiomics™ microvessels in Matrigel.
Here, we cultured microvessels in a 3mg/ml collagen matrix (our standard reference condition), a pure Matrigel matrix, and a 50:50 collagen:Matrigel matrix (final collagen concentration of 1.5mg/ml). Microvessels are used at a concentration of 100k vessels per ml in all groups. After gelling, angiogenic medium containing RPMI, B27, and 50ng/ml VEGF was added to constructs. After 7 days of culture, phase contrast images were analyzed using Advanced Solutions BioSegment™ Software. This software utilizes machine learning to identify vessel structures and automatically measures vascular-related parameters such vessel length density, a measure of vascularity.
Results and Discussion
Unlike the extent of angiogenesis by Angiomics™ microvessels cultured in 3D collagen, those cultured in only Matrigel displayed little to no angiogenesis with microvessels dissociating into single cells or single cell clumps (Figure 1). We have previously observed that angiogenic microvessels prefer some amount of fibrillar matrix in order to grow and maintain their structure. While stromal collagen provides this structure for the microvessels, Matrigel alone does not as it represents more of a basement membrane-like composition.
In contrast, a blend of collagen and Matrigel promoted robust angiogenesis to much higher total neovessel growth than controls with collagen only (Figure 2). This may be due to growth factors and other signaling molecules present within the Matrigel. Overall, while Matrigel alone may not support microvessel growth, blending Matrigel with other stromal matrices such as collagen may prove advantageous. Thus, incorporating Angiomics™ microvessels into Matrigel-based models and assays is an effective means of improving the biology of the model.
Advanced Solutions has a research lab based in Manchester, NH. You can learn more about hour Tissue & Assay Services here.