Tissue-Engineered Ligament: Cells, Matrix and Growth Factors

By offering new approaches to the scienific questions and clinical problems of ligament repair and replacement, the field of tissue engineering has significant potential for future research. Tissue engineering not only offers a potential technique to custom design ligament replacement grafts, but also it provides a new model for further understanding of basic principles important in ligament form and function. Future studies using biodegradable polymer scaffolds in vitro and in vivo will help to define and begin to answer basic questions about the role of cell to cell contact and signaling in ligament function and the exact source of the cells that initiate and regulate the healing process. These polymer scaffolds may also offer an important means to understand the signals from the surrounding three-dimensional matrix in modulating formation of ligament tissue. Experimentation with custom modification of the biologic and physical composition of the polymer scaffold may also help to elucidate the chemical and structural signals that are critical for healing at the graft-bone interface. It is hoped that understanding the effect of biologic and mechanical factors on ligament healing and repair will allow design of novel methods for graft engineering and attachment that will improve initial fixation strength as well as ultimate healing. By merging the technologies of biodegradable polymers, growth factor therapy, and the flexibility of an in vitro cell culture system, tissue engineering may offer a springboard for defining further the basic biologic principles important in ligament repair and, ultimately, lead to a new ligament replacement technology.