Cultrex 3-D Culture Matrix Reduced Growth Factor Basement Membrane Extract, Pathclear

All epithelial and endothelial cells are in contact with a basement membrane matrix on at least one of their surfaces. By providing them with their natural matrix in vitro as a substrate for the cells that provides biological cues, the cells can assume a more physiological morphology (i.e. correct shape) and begin expression of cell-lineage specific proteins. Two-dimensional plastic surfaces, in combination with serum-containing media, cause cells to flatten, proliferate and de-differentiate.

Cultrex BME should be stored at or below -20°C for optimal stability. Preparation of working aliquots is recommended. Cultrex BME should be thawed overnight on ice at 4°C, however long term storage at 4°C is not recommended. Freeze/thaw cycles and gel-liquid phase transitions should be avoided, since they can compromise product integrity.

Cultrex^® 3D Culture Matrix was developed to provide the most standardized basement membrane extract for use in 3D Cultures. A special process is employed to reduce growth factors. This material is then incorporated in a 3D culture to validate efficacy. 3D Culture Basement Membrane Extract promotes differentiation of a human epithelial cell line derived from mammary gland (MCF-10A) and human prostate (PC-3) into acinar structures. The Cultrex^® 3D Culture Matrix is essentially the same as our standard Cultrex^® BME, but has been additionally qualified with the functional 3D assay as described above.

The Tube Formation Assay is based on the ability of endothelial cells to form three-dimensional capillary-like tubular structures when cultured on a hydrogel of reconstituted basement membrane, such as Cultrex Basement Membrane Extract (BME).

The Tube Formation Assay is the most widely used in vitro angiogenesis assay. The assay is rapid, inexpensive and quantifiable. It can be used to identify potentially angiogenic and anti-angiogenic factors, to determine endothelial cell phenotype, and to study pathways and mechanisms involved in angiogenesis. It can be performed in a high throughput mode to screen for a large number of compounds.

The Tube Formation Assay is specific for endothelial cells, either primary cells or immortalized cell lines. Only endothelial cells form capillary-like structures with a lumen inside. Other endothelial cell types form other structures.

The major variables associated with tube formation are composition of the Cultrex Basement Membrane Extract (BME) hydrogel, thickness of the hydrogel, cell density, composition of angiogenic factors in the assay medium, and assay period.

Cultrex Reduced Growth Factor BME (RGF BME) is generally used for testing compounds that promote angiogenesis because formation of capillary-like structures (tubes) is significantly less compared to non-growth factor reduced varieties of Cultrex BME. The Cultrex In Vitro Angiogeneis Assay (Tube Formation) includes a qualified production lot of Cultrex RGF BME that exhibits reduced background tube formation in the absence of angiogenic factors.

Primary endothelial cells, such as Human Umbilical Vein Endothelial Cells (HUVECs) form capillary-like structures in the absence of added angiogenic factors less often than immortalized endothelial cells. Generally, reducing the number of cells per cm² plated onto Cultrex BME will result in less background or spontaneous tube formation. Titrate the number of cells and find optimal conditions for your specific cell line. When endothelial cells fully form capillary structures in response to angiogenic activators, but not in their absence, you may proceed.

Within the organoid, spheroid, or 3-D culture, cells may be assessed for morphology, apical/basal polarity, protein localization, and relative proliferation. In addition, cells may be isolated from the 3-D culture and evaluated for levels of RNA and protein expression, as well as modifications to DNA.

3-D cultures are in vitro cultures where immortalized cell lines, primary cell lines, stem cells, or tissue explants are placed within hydrogel matrices, such as Cultrex Basement Membrane Extract, that mimic in vivo cell environments and allow cells to proliferate in three dimensions.

While 2-D culture has been used for studying many aspects of cell function and behavior, the tissue-culture treated plastic environment is unlike anything found within living organisms. As a result, cells in 2-D culture exhibit altered morphology, function, proliferation, and gene expression when compared to their emanating tissues. By placing these cells in a 3-D environment, they assume biological and biochemical characteristics similar to what is observed in vivo.

The major variables associated with 3-D culture are cell type, cell seeding density, composition of hydrogel, thickness of hydrogel, stiffness of hydrogel, composition of cell culture medium, and time of culture.

The two principal methods for performing 3-D culture are the top assay and embedded assay. For the top assay, cells are seeded on a thick gel of Cultrex Basement Membrane Extract (BME) or Extracellular Matrix Protein. A thin overlay of cell culture medium is then applied to the cells. For the embedded assay, cells are resuspended within a thick gel of Cultrex BME or ECM and the culture media is applied on top. The top assay is easier to setup, to control seeding densities, and to keep cells within one focal plane for analysis.

Choice of matrix should correspond to the environment that you wish to recapitulate. Cultrex Basement Membrane Extract (BME) will recapitulate the basal lamina, which underlie most cells of epithelial or endothelial origin. Cultrex Collagen I is the major constituent of connective tissue, and is commonly inhabited by stationary cells, such as fibrocytes and adipose cells, as well as migrating cells, such as mast cells, macrophages, monocytes, lymphocytes, plasma cells, and eosinophils.

Cells need to be healthy and actively dividing in 2-D culture. Cells should be passaged two or three times after resuspension from cryopreservation, and they should never surpass 80% confluency during each passage. Cells should also be assessed for viability using trypan blue, and they should exhibit less than 5% staining.

In order for the Cultrex 3-D Culture Matrix RGF BME to stick to the plate, it must be tissue-culture treated.  However, if the application is spheroids or when using BME diluted in media as a slurry to form floating 3-D structures, then low attachment plates are recommended.