There has long been a need within the tissue engineering/regenerative medicine sector for three-dimensional reference scaffolds to serve as physical standards for the materials that are used as beds for the growth of cell cultures. The National Institute of Standards and Technology has created such references, which will eventually be accompanied by a proposed ASTM International standard that will provide instruction for use of the NIST scaffolds in cell culture testing.
The proposed ASTM standard, ASTM WK39698, Test Method: Using NIST Tissue Engineering Reference Scaffolds for Cell Culture Tests, is being developed by Subcommittee F04.42 on Biomaterials and Biomolecules for TEMPs, part of ASTM International Committee F04 on Medical and Surgical Materials and Devices.
Once approved, the proposed standard will be used hand-in-hand with the RM8394 NIST Reference Material scaffolds for cell culture (to be released in April 2013) as a stable, reproducible three-dimensional scaffold substrate for controls in scaffold development.
The proposed standard will provide users (including tissue engineers, those using 3-D for drug screening and in vitro disease models) with a very specific protocol for measuring cell adhesion and proliferation in a scaffold, using the NIST reference scaffolds as controls.
“Culture in 3-D scaffolds is much harder than on traditional flat culture dishes,” says Carl G. Simon Jr., Ph.D., a NIST biologist and F04 member. “Seeding cells onto 3-D scaffolds is more difficult due to their porous nature and because they are not attached to well bottoms.”
Simon notes other difficulties that make it challenging to get consistent results when testing 3-D scaffolds:
• Proliferation can be uneven due to uneven seeding and 3-D transport of nutrients and waste;
• Getting cells out of scaffolds due to pores can be hard, making it difficult to measure cell state; and
• Imaging cells is more difficult since scaffolds are opaque and the surfaces are uneven.
For all of these reasons, the NIST scaffolds and accompanying ASTM standard will serve as benchmarks for comparison to unknowns and enable interlaboratory comparisons.
All parties with an interest in 3-D cell culture are invited to join in the development of ASTM WK39698.
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ASTM Committee F04 Next Meeting: May 21-24, 2013, May Committee Week, Indianapolis, Ind.
Technical Contact: Carl G. Simon Jr., Ph.D., Biosystems and Biomaterials Division, National Institute of Standards and Technology, Gaithersburg, Md., Phone: 301-975-8574; firstname.lastname@example.org
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January 31, 2013