Bone regeneration in maxillary sinus augmentation surgery with mesenchymal stem cells: in vivo study in sheep

Abstract

Regeneration of soft and hard tissue defects with methods of tissue engineering are a major aim of modern medicine. Usually the reconstruction of tissue defects requires tissue transplantation from a healthy donor site. According to the size of the tissue defect a new defect in a healthy donor region with its own morbidity has to be created.Implant dentistry is the method of first choice when a functional and comfortable dental rehabilitation is to be considered in patients. Dental implants are today often the only possibility for a save and functional fixation of dentures in the atrophic alveolar process. But before dental implants can be inserted hard tissue augmentation is mostly necessary. Modern bone augmentation methods like sinusfloorelevation or onlay grafting even widen the range of indications for the use of implants. A growing, aging generation of people requires new approaches of augmentation methods that combine the advantages of autologous tissue transfer without the side effects arising through the harvesting procedure. Regeneration and remodelling of the human body is only possible with cells that continually regenerate themselves. Mesenchymal stem cells own this unique property. Mesenchymal stem cells and growth factors will play a major role in tissue regeneration with methods of tissue engineering. Aims: This research project consists of an in-vitro (already done) and an in-vivo part: The main focus in the in vitro part was the isolation and cultivation of stem cells using minimal invasive techniques under local anaesthesia using an outpatient protocol. With a specially developed commercially available centrifuge stem cells were separated from the bone marrow aspirate and concentrated within 20 minutes.Material and Methods: The in vivo part is done in a large animal experiment. After 14 days of in-vitro cultivation the constructs consisting of autologous stem cells, growth enhancing amino acids and a biomaterial are transplanted in the maxillary sinus in sheep (n= 9). Dental implants (Camlog) are inserted in the augmented sinus. During the animal study the animals will be injected with fluorescence colouring. At 8, 12 and 16 weeks the animals will be scarified. The integration of the augmentation material, the new bone formation influenced by the mesenchymal stem cells and the osseointegration of the titan-implants in 9 sheep are determined. By polychrome fluorescence labelling we determine the bone formation and the development of new bone over the time. With conventional X-ray pictures and CT scans examination of the bone grafts is possible. Light microscopy after scarification of the animals at different times can follow the new bone formation and the osseointegration of the titan implants.Statistical analysis (ANOVA) will be performed to analyze the results.After successful investigations in animals a possible clinical application in humans with atrophy of the alveolar process can be discussed. (AU)