Tissue engineering represents one of the most exciting advances in regenerative medicine. However, little has been reported on the application of tissue engineering for regeneration of periodontal tissues. Therefore, the aim of this study was to show how a technique based on tissue engineering principles can be applied to periodontology. Mesenchymal stem cells (MSCs) were isolated from a patient's iliac crest marrow aspirates. Platelet-rich plasma (PRP) was isolated from peripheral blood. Full-thickness periodontal flaps were elevated and the root surfaces were scaled and planed. A MSCs- PRP gel was prepared and applied to the root surface and adjacent defect space. The primary outcome measures were changes in pocket depth, clinical attachment level, bleeding on probing, and defect bone fill. Re-examination demonstrated that the treatment, including the application of MSCs-PRP gel at periodontal sites with angular defects, resulted in a 4-mm reduction in probing depths and a 4-mm clinical attachment gain, while bleeding and tooth mobility disappeared. Radiographic assessments showed that the bone defect had been reduced in depth. Interdental papillae supported by this tissue engineering technology regenerated. The use of MSCs in PRP gel might be helpful for periodontal tissue regeneration, treatment of esthetically sensitive sites, and reduction of patient morbidity.