Tissue engineering aims to regenerate and replace damaged or diseased tissues. It involves using scaffolds and growth factors to induce the body's own cells to assemble into new tissues. Recent progress includes growing skin grafts for burn victims and cartilage grafts for joint disease. However, complex organs remain difficult to engineer due to challenges with cell survival, function, and organization. If overcome, tissue engineering could help many of the millions who suffer from conditions currently lacking effective treatments like organ transplants.