Nanoscale borosilicate bioactive glass for regenerative therapy of full-thickness skin defects in rabbit animal model.

Bioactive glass (BG) occupies a significant position in the field of hard and soft tissue regeneration. Different processing techniques and formulas have been introduced to expand their regenerative, angiogenic, and antibacterial properties. In the present study, a new formula of bborosilicate bioactive glass nanofibers was prepared and tested for its wound-healing efficacy in a rabbit animal model. The glass formula ((1-2) mol% of B2O3 (68-69) mol% of SiO2, and (29-30) mol% of CaO) was prepared primarily by the sol-gel technique followed by the electrospinning technique. The material was characterized for its ultrastructure using scanning electron microscopy, chemical composition using FTIR, and its dynamic in vitro biodegradability using ICP-AES. Twelve rabbits were subjected to surgical induction of full-thickness skin defects using a 1 cm2 custom-made stainlessteel skin punch. The bioactive glass nanofibers were used as a grafting material in 6 experimental rabbits, while the defects in the remaining rabbits were considered as the negative control samples. All defects were assessed clinically for the decrease in wound size and clinical signs of healing and histologically for angiogenesis, collagen density, inflammatory response, cell recruitment, epithelial lining, and appendages at 1,2 and 3 weeks following the intervention. Structural analysis of the glass fibers confirmed their nano-size which ranged from 150 to 700 nm. Moreover, the chemical analysis confirmed the presence of SiO2 and B2O3 groups within the structure of the nanofibers. Additionally, dynamic biodegradation analysis confirmed the rapid degradation of the material starting from the first 24 h and rapid leaching of calcium, silicon, and boron ions confirming its bioactivity. The wound healing study of the nanofibrous scaffold confirmed its ability to accelerate wound healing and the closure rate in healthy rabbits. Histological analysis of the defects confirmed the angiogenic, regenerative and antibacterial ability of the material throughout the study period. The results unveil the powerful therapeutic properties of the formed nanofibers and open a new gate for more experimental and clinical applications.

Platelet rich plasma enhances osteoconductive properties of a hydroxyapatite-ß-tricalcium phosphate scaffold (Skelite) for late healing of critical size rabbit calvarial defects.

The use of platelet rich plasma (PRP) in bone repair remains highly controversial. In this work, we evaluated the effect of lyophilized PRP on bone regeneration when associated with a silicon stabilized hydroxyapatite tricalcium phosphate scaffold in a rabbit calvarial defect (Skelite). Critical defects were created in the calvaria of twenty-four rabbits. The periosteum was removed and the defects were either left empty or filled with allogeneic PRP gel; Skelite particles; Skelite and PRP gel. Four animals were killed after 4 weeks, 10 animals after 8 and 10 after 16 weeks. Specimens were processed for X-ray microtomography (µCT) and for resin embedded histology. µCT analysis revealed significant osteoid-like matrix and new bone deposition in PRP + Skelite group at both 8 and 16 weeks in respect to Skelite alone. Histologically, PRP + Skelite defects were highly cellular with more abundant osteoid deposition and more regular collagen fibres. Moreover, in vitro migration assays confirmed the chemotactic effect of PRP to endothelial and osteoprogenitor cells. We conclude that the addition of PRP influenced the local tissue microenvironment by providing key cryptic factors for regeneration, thereby enhancing progenitor cell recruitment, collagen and bone matrix deposition, and by creating a bridging interface between the scaffold and bone.

Experimental formation of periodontal structure around titanium implants utilizing bone marrow mesenchymal stem cells: a pilot study.

Tissue engineering in the head and neck area, presents numerous advantages. One of the most remarkable advantages is that regeneration of only a small amount of tissue can be highly beneficial to the patient, particularly in the field of periodontal tissue regeneration. For decades, successful osseointegration has provided thousands of restorations that maintain normal function. With the increasing need to utilize dental implants for growing patients and enhance their function to simulate normal tooth physiology and proprioception, there appears to be an urgent need for t concept of periodontal tissue regeneration around dental implants. In the present work, 5 goats wer used for immediate implant placement post canine teeth extraction. Each goat received 2 implan fixtures; the control side received a porous hollow root-form poly (DL-Lactide-co-Glycolide) scaf around the titanium fixture, and the experimental side received the same scaffold but seeded with autogenous bone marrow-derived mesenchymal stem cells. One animal was killed 10 days postoperatively, and the others were killed after 1 month. The results showed that on th experimental side, periodontal-like tissue with newly formed bone was demonstrated both at 1 days and after 1 month, while the control specimens showed early signs of connective tissue regeneration around the titanium fixture at 10 days, but was not shown in the 1 month specimens. I can be concluded that undifferentiated mesenchymal stem cells were capable of differentiating t provide the 3 critical tissues required for periodontal tissue regeneration: cementum, bone, a periodontal ligament. This work may provide a new approach for periodontal tissue regeneration.

Preservation and regeneration of alveolar bone by tissue-engineered implants.

Bone maintenance after dental extraction has a significant impact on the success of future treatment. The purpose of this study was to regenerate bone by implanting an engineered porous scaffold seeded with bone marrow mesenchymal stem cells (BMSCs) in a socket created by extraction of the lower left central incisor in rabbits, utilizing the principles of tissue engineering. It involved preparation and characterization of three-dimensional porous hollow root form scaffolds consisting of a poly-L-lactic acid:polyglycolic acid composite (PLG, 50:50), using a solvent casting/compression molding/particulate leaching technique. Porosity of the scaffolds was 83.71% with good interconnectivity and uniform distribution of the various pore sizes. The degraded scaffolds maintained their porosity and form for the first 2 weeks and their mass loss continued up to 6 weeks. The scaffolds developed viscoelastic behavior under dynamic compression; yet they lost their mechanical characteristics as they degraded. The scaffolds were seeded with BMSCs and examined by scanning electron microscopy. Cell proliferation and scaffold degradation were shown up to 2 weeks in vitro. The cultivated scaffolds were implanted in empty extraction sockets immediately after tooth removal. Four weeks later, bone regeneration was evaluated histologically in the healed sockets in three experimental groups: sockets left empty, sockets that received PLG without cells, and sockets that received PLG with cells. Radiographic evaluation, performed 4 weeks later for the three experimental groups, demonstrated preservation of alveolar bone walls in the extraction sockets that received PLG with cells as compared with the other two groups. The bone density profile for the healed sockets confirmed both histological and radiographic findings. The results of this study show promise in the area of dentoalveolar surgery, yet longitudinal studies under variable clinical situations would encourage the current application.