Extracel™-X for Tumor Xenografts
Extracel-X improves the repeatability of your tumor xenograft experiments. Since Extracel-X is manufactured in the laboratory, there is high lot-to-lot uniformity. It is also made from widely-available starting materials so that consistent supply is ensured. Extracel-X is murine product-free and so it is LDEV-free also. Additionally, the user determines the Extracel-X gelation time so that Extracel-X forms a gel in your mouse, not in your syringe.
Human primary tumor (T) after injection of MiaPaCa-2 cells mixed with Extracel™
Extracel-X Kit Contents
The Extracel-X kit comes as three vials containing chemically-modified hyaluronan, gelatin, and crosslinker (Glycosil, Gelin-S, and Extralink, respectively). The vials’ contents are reconstituted within thirty minutes at 37 °C with water enclosed in the kit. There is no need for an overnight slow thaw at 4 °C. Additionally, the kit can be purchased in one of two sizes: 7.5 ml (3 x 2.5 ml aliquots) for small-scale experiments and 12.5 ml (1 x 12.5 ml aliquot) for large experiments.
How Gelation Works
Extracel-X gelation depends solely on the addition of the Extralink™ crosslinker to Glycosil and Gelin-S. Unlike other commercially available matrices, there is no need to shift temperatures for gelation. Syringes no longer need to be kept cold to prevent gelation within the needle. In addition, gelation occurs at physiological pH. This means that your cells will never experience a cold or low pH shock.
Recommended Use
After Glycosil and Gelin-S are mixed together in a 1:1 volume ratio, an equal volume of the desired tumor cells are added. After Extralink is added, gelation occurs in about 2 hours which leaves the researcher ample time to inject a large number of animals. The recommended final concentration of added cells is at least 50 x 106 cells/ml.
Examples of Use
Extracel-X has been used successfully in growing orthotopic tumors in nude mice from a variety of cell lines (1, 2). When compared to media alone, Extracel-X showed improved growth and take rates, less tumor size variability, improved vascularization and reduced necrosis within tumor, reduced cancer seeding on adjacent tissues, and better animal health (1).
Extracel-X has also been used to grow subcutaneous tumors with tumor growth and take rates comparable to or better than those of Matrigel™. Shown below is an example from a tumor xenograft study with the COLO 205 (colon) cell line (100 ml injections, 5x106 cells final concentration, Nu/Nu mice):
Table legend: Colo205 tumors grow similarly in Extracel-X or Matrigel. Nude mice (n=5, two injections per mouse) were injected with 5x106 cells mixed with either Extracel-X (closed circles) or Matrigel (closed triangles). Tumor weight (data not shown) was measured weekly for tumor burden evaluation starting day 0. Tumor volume was measured 3 days per week starting on day 7.
References
- Liu Y, Shu XZ, Prestwich GD, Tumor engineering: orthotopic cancer models in mice using cell-loaded, injectable, cross-linked hyaluronan-derived hydrogels. Tissue Engineering 2007 May;13:1091-101.
- Torgenson MJ, Shea JE, Firpo MA, Dai Q, Mulvihill SJ, Scaife CL, Natural history of pancreatic cancer recurrence following “curative” resection in athymic mice, Journal of Surgical Research 2007 in press.