Building a meniscus. Biologic considerations.

Creating a tissue engineered meniscus requires that specific biologic considerations such as cell type, matrix scaffold, bioreactor design (in vitro, in vivo, or both), and environmental conditions (media, cytokines, physical stimuli) be addressed. Meniscal cells, fibroblasts, and mesenchymal stem cells have been proposed as potential cell sources and have been grown (either in vivo or in vitro) on various cell matrices including collagen based scaffolds, biodegradable polymers, and small intestine submucosa. In addition, various environmental factors (nutrients, growth factors) have been used to optimize cell proliferation in vitro. Although these tissue engineering paradigms have produced a meniscuslike construct, the long term functional capabilities of this engineered tissue have yet to be proven. The concept of tissue engineering holds great promise for the generation of tissues or organs unable to repair or regenerate themselves. In terms of the meniscal tissue, however, the principles of tissue engineering may be best used to enhance and optimize the natural regeneration of the meniscus.