Engineered autologous bone marrow mesenchymal stem cells: alternative to cleft alveolar bone graft surgery.

Human recombinant bone morphogenetic protein 2 (rhBMP-2) accelerates bone regeneration but is associated with limited cementum and periodontal ligament regeneration, local root resorption, and ankylosis. This study assessed a new approach to the regeneration of the alveolar bone and periodontal attachment apparatus using a combination of ex vivo autologous bone marrow mesenchymal stem cells (MSCs) engineered by replication defective adenovirus to express the BMP-2 gene and pluronic F127 (PF127) in a large mammalian animal model. Bilateral maxillary periodontal defects were created over the premolar area in 9 mature male miniature swine. The 18 defects were randomly assigned to receive either BMP-2-expressing MSCs in the advBMP-2 group or MSCs alone in the MSC group. The regenerated periodontal attachment apparatus was evaluated histologically, and the total regenerated bone volume was calculated from three-dimensional computed tomography analysis. Three months after implantation, significant bone volume was regenerated in the advBMP-2 group. Periodontal apparatus regeneration was significantly better in the advBMP-2 group. New cementum and Sharpey fibers were observed on the denuded root surfaces in the advBMP-2 group, whereas incomplete healing with localized root surface resorption was noted in the control group. The use of ex vivo BMP-2-engineered autologous MSCs enhanced bone and periodontal apparatus regeneration in maxillary alveolar and periodontal defects in swine. This novel integrated approach might be suitable for clinical periodontal apparatus repair. This may be an alternative for cleft alveolar bone graft surgery.

Mandibular alveolar bony defect repair using bone morphogenetic protein 2-expressing autologous mesenchymal stem cells.

BACKGROUND: Mandibular bone regeneration is stepped up by human recombinant bone morphogenetic protein 2 (BMP-2) whose application is also related to limited cementum and periodontal ligament regeneration, local root resorption, and ankylosis. The alveolar bone grafting without traditional autologous bone grafts remains a challenge for plastic surgeons. METHODS: Bilateral mandibular alveolar and periodontal defects were created over the premolar areas in 9 mature male beagles. The defects were randomly assigned for either the adenovirus BMP-2 (advBMP-2) group with BMP-2-expressing mesenchymal stem cells (MSCs) or the control with MSCs alone. The regenerated periodontal attachment apparatus was evaluated histologically, and the whole regenerated bone volume was scrutinized from three-dimensional computed tomography analysis. RESULTS: Periodontal apparatus regeneration was significantly better in the advBMP-2 group. New cementum and Sharpey fibers were observed on the denuded root surfaces in the advBMP-2 group, whereas incomplete healing with localized root surface resorption was noted in the control group. Eight weeks after implantation, the advBMP-2 group showed significant increase in bone regeneration than the control one. CONCLUSIONS: Thus, the use of ex vivo BMP-2-engineered autologous MSCs boosted bone and periodontal apparatus regeneration in mandibular periodontal defects. This de novo approach might be suitable for clinical mandibular bone repair and periodontal apparatus repair.

The occlusion-adjusted prefabricated 3D mirror image templates by computer simulation: the image-guided navigation system application in difficult cases of head and neck reconstruction.

Computer applications in head and neck reconstruction are rapidly emerging and create not only a virtual environment for presurgical planning, but also help in image-guided navigational surgery. This study evaluates the use of prefabricated 3-dimensional (3D) mirror image templates made by computer-simulated adjusted occlusions to assist in microvascular prefabricated flap insertion during reconstructive surgery. Five patients underwent tumor ablation surgery in 1999 and survived for 8 years. Four of the patients with malignancy received radiation therapy. All patients in this study suffered from severe malocclusion causing trismus, headache, temporomandibular joint pain, an unsymmetrical face, and the inability of further osseointegrated teeth insertion. They underwent a 3D computer tomography examination and the nonprocessed raw data were sent for computer simulation in adjusting occlusion; thus, a mirror image template could be fabricated for microsurgical flap guidance. The computer simulated occlusion was acceptable and facial symmetry obtained. The use of the template resulted in a shorter operation time and recovery was as expected. The computer-simulated occlusion-adjusted 3D mirror image templates aid in the use of free vascularized bone flaps for restoring continuity to the mandible. The coordinated arch will help with further osseointegration teeth insertion.

Repair of large cranial defects by hBMP-2 expressing bone marrow stromal cells: comparison between alginate and collagen type I systems.

Despite a wide range of available sources for bone repair, significant limitations persist. To bioengineer bone, we have previously transferred adenovirus-mediated human BMP-2 gene into autologous bone marrow stromal cells (MSC). We have successfully repaired large, full thickness, cranial defects using this approach. We report now the effectiveness of various hydrogels as the scaffold for this type of bone regeneration, comparing specifically alginate with Type I collagen. Cultured MSC of miniature swine were infected with BMP-2 or beta-gal adenovirus 7 days before implantation. These cells were mixed with alginate, ultrapure alginate, alginate-RGD, or type I collagen to fabricate the MSC/biomaterial constructs. The results of cranial bone regeneration were assessed by gross examination, histology, 3D CT, and biomechanical tests at 6 weeks and 3 months after implantation. We found that the BMP-2 MSC/collagen type I construct, but not the beta-gal control, effectively achieved nearly complete repair of the cranial defects. No bone regeneration was observed with the other hydrogels. Biomechanical testing showed that the new bone strength was very close and only slightly inferior to that of normal cranial bone. Controlling for the integration of stem cells and ex vivo gene transfer, the alginate scaffolds has a significant negative impact on the success of the construct. Our study demonstrates better bone regeneration by collagen type I over alginate. This may have therapeutic implications for tissue engineered bone repair.

Large-scale bicortical skull bone regeneration using ex vivo replication-defective adenoviral-mediated bone morphogenetic protein-2 gene-transferred bone marrow stromal cells and composite biomaterials.

OBJECTIVE: Bone marrow stromal cells (BMSCs) have great potential in bone repair. We developed an animal model to test the hypothesis that ex vivo gene transfer of human bone morphogenetic protein (BMP)-2 to BMSCs via a replication-defective (E1A-deleted) adenovirus vector (AdV) with appropriate biopolymers would enhance autologous bone formation during repair of a large-scale skull defect. METHODS: Eighteen miniature swine were treated with AdV BMP-2-transduced BMSCs in biopolymer (group 1), BMSCs in biopolymer (group 2), or biopolymer alone (group 3). After 6 months, the swine were killed, and the skull repair was examined by gross pictures, histology, 3-dimensional computed tomography, and biomechanical study. RESULTS: Group 1 showed complete solid bone formation after 6 months, and hematoxylin and eosin staining demonstrated the presence of mature, woven, well-mineralized bone. Computed tomography showed wholesome repair of the skull defect. Statistical analysis demonstrated a significant difference in bone thickness between groups 1 and 2. Biomechanical testing showed a statistically significant difference in the stiffness of new bone formed in group 1 compared with group 2. CONCLUSION: The Ad5 E1A-deleted AdV may be the optimal starting vector in ex vivo gene therapy for benign skeletal diseases. Additionally, the use of the gelatin/tricalcium phosphate ceramic/glutaraldehyde biopolymer with AdV BMP-2 gene transfer strongly enhances the bony healing of critical-size bicortical craniofacial defects. This method can be used by modifying the delivery of constructs to malunion treatment, in regional osteoporosis therapy, and spinal fusion.