Nanofabrication and microfabrication of functional materials for tissue engineering.

The burgeoning field of regenerative medicine promises significant progress in the treatment of cardiac ischemia, liver disease, and spinal cord injury. Key to its success will be the ability to engineer tissue safely and reliably. Tissue functionality must be recapitulated in the laboratory and then integrated into surrounding tissue upon transfer to the patient. Scaffolding materials must be chosen such that the microenvironment surrounding the cells is a close analog of the native environment. In the early days of tissue engineering, these materials were largely borrowed from other fields, with much of the focus on biocompatibility and biodegradation. However, attention has shifted recently to cell-cell and cell-surface interactions, largely because of enabling technologies at the nanoscale and microscale. Studies on cellular behavior in response to various stimuli are now easily realized by using microfabrication techniques and devices (e.g., biomedical microelectromechanical systems). These experiments are reproducible and moderate in cost, and often can be accomplished at high throughput, providing the fundamental knowledge required to design biomaterials that closely mimic the biological system. It is our opinion that these novel materials and technologies will bring engineered tissues one step closer to practical application in the clinic. This review discusses their application to cardiac, liver, and nerve tissue engineering.