Construction of adipose scaffold for bone repair with gene engineering bone cells

Application of Bovine Acellular Cancellous Bone Matrix in Alveolar Ridge Preservation Following Tooth Extraction

Objective: In this article, we explored the microscopic structure and composition of the decellular-ized cancellous bone matrix of the calf, and established the animal model of Beagle dog extraction. By applying different bone substitute materials in the extraction of teeth, we observed the new collagen-rich in the preservation of the site after tooth extraction. The protein bone matrix maintained the three-dimensional shape of the alveolar ridge compared to other biological materials. Methods: The microstructure of the new collagen-rich bone matrix was observed by scanning electron microscopy. The porous structure, porosity and distribution of collagen fibers were observed. XRD and infrared spectroscopy were used to further detect the inorganic and organic components in the new collagen-rich bone matrix. The premolar extraction and site preservation model of Beagle dogs were constructed. The changes of collagen-rich bone matrix, Bio-oss bone powder, CGF filling and blank control alveolar ridge volume were compared by CBCT. HE staining was used to observe and compare new bone formation, bone remodeling and bone resorption between groups, and to observe the formation of blood vessels, osteogenic mineralization, trabecular bone formation and inflammatory response in different periods. Results: (1) The acellular bone matrix of bovine cancellous bone completely removes the immunogenicity of the cells and has good histocompat-ibility; the pore diameter and porosity closest to the physiological structure, the main component is hydroxyapatite and collagen. (2) Site preservation can reduce the absorption of alveolar ridge following tooth extraction, preserve sufficient bone mass for alveolar fossa, and retain a good width of attachment, which provides further protection for implant surgery. (3) In the post-extraction site preservation, the CGF group has better bone composition than the BABM group and Bio-oss bone powder. Conclusion: Bovine Acellular Cancellous Bone Matrix is a new type of biological bone matrix. The main components are collagen and hydroxyapatite, which can promote bone formation in the extraction socket.

Decellularized Adipose Tissue Hydrogel Promotes Bone Regeneration in Critical-Sized Mouse Femoral Defect Model

Critical-sized bone defects fail to heal and often cause non-union. Standard treatments employ autologous bone grafting, which can cause donor tissue loss/pain. Although several scaffold types can enhance bone regeneration, multiple factors limit their level of success. To address this issue, this study evaluated a novel decellularized human adipose tissue (DAT) hydrogel as an alternative. In this study, DAT hydrogel alone, or in combination with adipose-derived stromal/stem cells (ASC), osteo-induced ASCs (OIASC), and hydroxyapatite were tested for their ability to mediate repair of a critical-sized (3 mm) femoral defect created in C57BL/6 mice. Micro-computed tomography results showed that all DAT hydrogel treated groups significantly enhanced bone regeneration, with OIASC + hydroxyapatite treated group displaying the most robust bone regeneration. Histological analyses revealed that all treatments resulted in significantly higher tissue areas with the relative mineralized tissue area significantly increased at 12 weeks; however, cartilaginous content was lowest among treatment groups with OIASC. Immunohistochemical analyses showed that DAT hydrogel enhanced collagen I and osteopontin expression, while the addition of OIASCs to the hydrogel reduced collagen II levels. Thus, DAT hydrogel promotes bone regeneration in a critical-sized femoral defect model that is further enhanced in the presence of OIASCs and hydroxyapatite.

Comparison of bone regeneration in alveolar bone of dogs on mineralized collagen grafts with two composition ratios of nano-hydroxyapatite and collagen

To study the effect of two composition ratios of nano-hydroxyapatite and collagen (NHAC) composites on repairing alveolar bone defect of dogs. Eighteen healthy adult dogs were randomly divided into three groups. Two kinds of the NHAC composites were prepared according to the constituent ratios of 3:7 and 5:5; immediately after extraction of the mandibular second premolars, each kind of the NHAC composite was implanted into extraction socket, respectively: Group I, nHA/Col = 3:7; Group II, nHA/Col = 5:5 and Group III, blank control group. The bone-repairing ability of the two grafts was separately analyzed by morphometric measurement, X-ray tomography examination and biomechanical analysis at 1st, 3rd and 6th month post-surgical, respectively. The NHAC composites were absorbed gradually after implanting into alveolar bone defect and were replaced by new bone. The ratios of new bone formation of Group I was significantly higher than that of Group II after 3 months (P < 0.05). The structure and bioactive performance can be improved when the ratio between the collagen and the hydroxyapatite was reasonable, and the repairing ability and effect in extraction sockets are obviously better.

Stem cell regenerative therapy in alveolar cleft reconstruction

Achieving a successful and well-functioning reconstruction of craniofacial deformities still remains a challenge. As for now, autologous bone grafting remains the gold standard for alveolar cleft reconstruction. However, its aesthetic and functional results often remain unsatisfactory, which carries a long-term psychosocial and medical sequelae. Therefore, searching for novel therapeutic approaches is strongly indicated. With the recent advances in stem cell research, cell-based tissue engineering strategies move from the bench to the patients' bedside. Successful stem cell engineering employs a carefully selected stem cell source, a biodegradable scaffold with osteoconductive and osteoinductive properties, as well as an addition of growth factors or cytokines to enhance osteogenesis. This review highlights recent advances in mesenchymal stem cell tissue engineering, discusses animal models and case reports of stem cell enhanced bone regeneration, as well as ongoing clinical trials.