A tissue engineering, cell-based therapeutic approach could be essential for extensive bone or cartilage reconstruction. This article is divided in two chapters and describes new cell-based surgical techniques for cartilage and bone reconstruction. In the first part on bone reconstruction, marrow-derived osteogenic progenitor cells combined with hydroxyapatite were utilized. The validity of this model has been shown for the repair of critical size bone defects in large size animal models. We used this cell-based therapeutic approach to treat 3 patients with large bone defects, achieving bone reconstruction.