Construction of a mineralized collagen nerve conduit for peripheral nerve injury repair.

A new nerve guidance conduits (NGCs) named MC@Col containing Type I collagen (Col) and mineralized collagen (MC) was developed, enhancing mechanical and degradation behavior. The physicochemical properties, the mechanical properties and in vitro degradation behavior were all evaluated. The adhesion and proliferation of Schwann cells (SCs) were observed. In the in vivo experiment, MC@Col NGC and other conduits including Col, chitosan (CST) and polycaprolactone (PCL) conduit were implanted to repair a 10-mm-long Sprague-Dawley rat's sciatic nerve defect. Histological analyses, morphological analyses, electrophysiological analyses and further gait analyses were all evaluated after implantation in 12 weeks. The strength and degradation performance of the MC@Col NGC were improved by the addition of MC in comparison with pure Col NGC. In vitro cytocompatibility evaluation revealed that the SCs had good viability, attachment and proliferation in the MC@Col. In in vivo results, the regenerative outcomes of MC@Col NGC were close to those by an autologous nerve graft in some respects, but superior to those by Col, CST and PCL conduits. The MC@Col NGC exhibited good mechanical performance as well as biocompatibility to bridge nerve gap and guide nerve regeneration, thus showing great promising potential as a new type of conduit in clinical applications.

Biphasic mineralized collagen-based composite scaffold for cranial bone regeneration in developing sheep.

Appropriate mechanical support and excellent osteogenic capability are two essential prerequisites of customized implants for regenerating large-sized cranial bone defect. Although porous bone scaffolds have been widely proven to promote bone regeneration, their weak mechanical properties limit the clinical applications in cranioplasty. Herein, we applied two previously developed mineralized collagen-based bone scaffolds (MC), porous MC (pMC) and compact MC (cMC) to construct a biphasic MC composite bone scaffold (bMC) to repair the large-sized cranial bone defect in developing sheep. A supporting frame composed of cMC phase in the shape of tic-tac-toe structure was fabricated first and then embedded in pMC phase. The two phases had good interfacial bond, attributing to the formation of an interfacial zone. The in vivo performance of the bMC scaffold was evaluated by using a cranial bone defect model in 1-month-old sheep. The computed tomography imaging, X-ray scanning and histological evaluation showed that the pMC phase in the bMC scaffold, similar to the pMC scaffold, was gradually replaced by the regenerative bone tissues with comprehensively increased bone mineral density and complete connection of bone bridge in the whole region. The cMC frame promoted new bone formation beneath the frame without obvious degradation, thus providing appropriate mechanical protection and ensuring the structural integrity of the implant. In general, the sheep with bMC implantation exhibited the best status of survival, growth and the repair effect. The biphasic structural design may be a prospective strategy for developing new generation of cranioplasty materials to regenerate cranial bone defect in clinic.

Tuning pore features of mineralized collagen/PCL scaffolds for cranial bone regeneration in a rat model.

Porosity is indispensable for a bone tissue-engineered scaffold for facilitating endogenous cell migration and nascent bone ingrowth. In large-sized cranial bone defect repair, porous scaffolds meet great challenges to match cranial bone regeneration and provide sufficient protection with structural integrity. Therefore, the pore features of the scaffolds for cranial bone regeneration should differ from those typical porous scaffolds used in tubular bone repair and be finely tuned. In this study, a series of porous mineralized collagen/PCL scaffolds with different pore features were fabricated via freeze-drying and applied in a Sprague Dawley rat cranial bone calvarial defect model. The pore size for four groups increased from 10-45 µm to 40-130 µm. As scaffold porosity increased, the compressive strength decreased from 2.09 ±â€¯0.12 MPa to 0.51 ±â€¯0.04 MPa. The micro-computed tomography three-dimensional reconstruction images showed that as pore size and porosity increased, the amount of new bone formation had a maximum in group 3 (pore size: 20-100 µm, compressive strength: 1.06 ±â€¯0.03 MPa). In addition, the histological and histomorphometric analyses showed a consistent tendency which confirmed the Micro-CT results. Meanwhile, histological findings including bony bridging, tissue response at the bone-implant interface and fibrous capsule thickness indicated that the dura mater pathway played the most important role in the regenerative process of this calvarial defect model.

A high-strength mineralized collagen bone scaffold for large-sized cranial bone defect repair in sheep.

Large-sized cranial bone defect repair presents a great challenge in the clinic. The ideal cranioplasty materials to realize the functional and cosmetic recovery of the defect must have sufficient mechanical support, excellent biocompatibility, good osseointegration and biodegradability as well. In this study, a high-strength mineralized collagen (MC) bone scaffold was developed with biomimetic composition, microstructure and mechanical properties for the repair of sheep large-sized cranial bone defects in comparison with two traditional cranioplasty materials, polymethyl methacrylate and titanium mesh. The compact MC scaffold showed no distinct pore structure and therefore possessed good mechanical properties. The strength and elastic modulus of the scaffold were much higher than those of natural cancellous bone and slightly lower than those of natural compact bone. In vitro cytocompatibility evaluation revealed that the human bone marrow mesenchymal stem cells (hBMSC) had good viability, attachment and proliferation on the compact MC scaffold indicating its excellent biocompatibility. An adult sheep cranial bone defect model was constructed to evaluate the performances of these cranioplasty materials in repairing the cranial bone defects. The results were investigated by gross observation, computed tomography scanning as well as histological assessments. The in vivo evaluations indicated that compact MC scaffold showed notable osteoconductivity and osseointegration with surrounding cranial bone tissues by promoting bone regeneration. Our results suggested that the compact MC scaffold has a promising potential for large-sized cranial bone defect repair.

[Application of biomimetic mineralized collagen bone graft material in rabbits posterolateral spinal fusion].

Objective: To investigate the bone repair and regeneration ability of biomimetic mineralized collagen bone graft material and autologous bone marrow in rabbit posterolateral spinal fusion model. Methods: Twenty-seven 20-week-old male New Zealand white rabbits ï¼»weighing (5.0±0.5) kgï¼½ were used to establish the posterolateral spinal fusion model of L 5 and L 6 segments by stripping the transverse process and exposing cancellous bone with electric burr. The rabbits were randomly divided into 3 groups, 9 in each group. Groups A, B, and C were implanted 1.5 mL autologous iliac bone, 1.5 mL (30 mm×10 mm×5 mm) biomimetic mineralized collagen bone graft material, and 1.5 mL (30 mm×10 mm×5 mm) biomimetic mineralized collagen bone graft material and autologous bone marrow in each bone defect. At 4, 8, and 12 weeks after operation, the apparent hardness of the bone grafting area was observed by manipulation method, in order to evaluate bone graft fusion effects. Three animals were sacrificed in each group at each time point, the vertebral body specimens were excised and the bone defect repair and fusion were observed by X-ray films, and three-dimensional CT examination was performed to evaluate whether new bone was formed in the body. HE staining was performed at each time point to observe the formation of new bone and the repair and fusion of bone defects. Results: The manipulation test showed that bone graft fusion was not found in all groups at 4 weeks after operation; 3 (50.0%), 2 (33.3%), and 4 (66.7%) of groups A, B, and C reached bone graft fusion at 8 weeks after operation; 5 (83.3%), 4 (66.7%), and 5 (83.3%) of groups A, B, and C reached bone graft fusion at 12 weeks after operation; the fusion rate of group C was similar to that of group A, and all higher than that of group B. X-ray film observation showed that the fusion rate of group C at 8 and 12 weeks after operation was higher than that of group B, similar to group A. Three-dimensional CT observation showed that the effect of bone fusion in group C was better than that in group B, which was close to group A. HE staining observation showed that large area of mature lamellar bone coverage appeared in the bone graft area of groups A, B, and C at 12 weeks after operation, the material was completely degraded, and the marginal boundary of the host bone disappeared and tightly combined. Conclusion: Biomimetic mineralized collagen bone graft material mixed with autologous bone marrow has good osteoinduction and osteogenesis guidance. Compared with biomimetic mineralized collagen bone graft material, it has better and faster osteogenesis effect, which is close to autologous bone transplantation.

Locking system strengthened by biomimetic mineralized collagen putty for the treatment of osteoporotic proximal humeral fractures.

The current study is to observe the effect of the locking system strengthened by biomimetic mineralized collagen putty for the treatment of senile proximal humeral osteoporotic fractures. From January 2012 to December 2015, 80 cases of senile patients with osteoporotic proximal humeral fractures were randomly divided into an observation group and a control group, each group with a total of 40 cases. The control group was simply treated with locking plate. The observation group was treated with locking plate in combination with biomimetic mineralized collagen putty. The therapeutic effect thereby was observed. The excellent and satisfactory rate was 90% in observation group and was 72.5% in control group. The difference between the two groups was statistically significant (χ2 = 5.3312, P < 0.05). The fracture healing time was 11.82 ± 3.62 weeks in observation group and 19.78 ± 5.46 weeks in control group. The shoulder joint function score was 89.63 ± 8.12 in observation group and 76.92 ± 8.18 in control group. There was significant difference between the two groups (t = 7.1272; 12.7834, P < 0.05). The complication rate was 10% in the observation group and 32.5% in the control group (χ2 = 7.3786, P < 0.05). Locking system strengthened by biomimetic mineralized collagen putty has advantages such as accelerating healing of senile proximal humeral fracture, improving the therapeutic effect, reducing the complications. As one of the optimal internal fixation method, it provides a new option for better treatment of senile osteoporotic fracture.

Mineralized Collagen-Based Composite Bone Materials for Cranial Bone Regeneration in Developing Sheep.

Cranial bone defects remain a great challenging problem in clinical settings, the influences of which are serious because of the intricate complications and related social problems, especially for young children with rapidly growing skulls. Currently, an increasing number of bone materials are being developed for cranial bone defects repair. In this study, two different biodegradable composite bone materials based on mineralized collagen (MC), with compact/porous structure, were constructed to promote bone regeneration for large cranial bone defect repair of one-month-old baby sheep. The porous MC (pMC) scaffold had interconnected porous structure with a porosity of about 73% and a 20-150 µm pore size range, and the compact MC (cMC) showed no distinct pore structure. Mechanical tests indicated that the compressive strength and elastic modulus of cMC and pMC were comparable with those of natural compact and cancellous bone, respectively. Both of these two MC scaffolds possessed good biocompatibility and supported osteoblasts adhesion and proliferation in vitro. A one-month-old sheep cranial bone defect model was first established to investigate the cranial bone regeneration behaviors in vivo, which was evaluated by CT imaging, X-rays scans, and histological assessments. It was found that the pMC promoted bone ingrowth from the diploic layer of surrounding cranium and dura mater-derived osteogenesis at three months after surgery, along with gradual biodegradation. In contrast, the cMC had very little biodegradation but could promote bone formation beneath the scaffold through dura mater-derived osteogenesis pathway. Furthermore, Ti-mesh restricted the growth of surrounding cranial bone in the rapidly growing sheep, thereby causing obvious deformation of the skull at six months after surgery, whereas no visible geometric deformation of skull occurred in the cMC and pMC groups. Our findings suggested that the MC-based composite bone materials have great promise for the repair of large cranial bone defects in a developing skull.

Clinical evaluations of mineralized collagen in the extraction sites preservation.

The purpose of this study was to explore the different effects between biomimetic mineralized collagen (MC) and ordinary physically blended hydroxyapatite/collagen (HA/Col) composite in evaluating new bone formation and regenerated bone height in human extraction sockets. Thirty-four patients who cannot retain teeth caused by trauma or decay were randomly selected from Department of Stomatology of Dongzhimen Hospital from December 2013 to December 2014. The patients were randomly divided into two groups. After the operation of tooth extraction, 17 patients were implanted with biomimetic MC (MC group), and other 17 patients were implanted with ordinary physically blended nHA/Col composite (nHA/Col group). X-ray positioning projection by auto-photographing was taken to test the distance between the lowest position and the neighboring CEJm-CEJd immediately, 1 month and 3 months after the operation. The height of new bone formation of the MC group was significantly higher than the nHA/Col group. Biomimetic MC showed better clinical outcomes in the bone formation for extraction site preservation and would have broad application prospect in the field of oral and maxillofacial surgeries.

Test in canine extraction site preservations by using mineralized collagen plug with or without membrane.

The aim of this study was to discuss the feasibility of porous mineralized collagen plug and bilayer mineralized collagen-guided bone regeneration membrane in site preservation in extraction sockets. The third mandibular premolars on both sides were extracted from four dogs, thus there were 16 alveolar sockets in all dogs and were randomly assigned into three groups. Group A had six alveolar sockets, and groups B and C had five alveolar sockets, respectively. Each alveolar socket of group A was immediately implanted with a porous mineralized collagen plug and covered with a bilayer mineralized collagen-guided bone regeneration membrane after tooth extraction. Alveolar sockets of group B were implanted with porous mineralized collagen plug only, and group C was set as blank control without any implantation. The healing effects of the extraction sockets were evaluated by gross observation, morphological measurements, and X-ray micro-computed tomography after twelve weeks. Twelve weeks after operation, both groups A and B had more amount of new bone formation compared with group C; in terms of the degree of alveolar bone height, group A was lower than groups B and C with significant differences; the bone mineral density in the region of interest and bone remodeling degree in group A were higher than those of groups B and C. As a result, porous mineralized collagen plug could induce the regeneration of new bone in extraction socket, and combined use of porous mineralized collagen plug and bilayer mineralized collagen guided bone regeneration membrane could further reduce the absorption of alveolar ridge and preserve the socket site.

A new method to standardize CBCT for quantitative evaluation of alveolar ridge preservation in the mandible: a case report and review of the literature.

Cone-beam computerized tomography (CBCT) is an effective technique for assessment of changes to the alveolar ridge (AR). However, its accuracy and reliability could be improved by standardization of imaging positions to remain unchanged during measurements. In this study, an alveolar ridge preservation procedure was performed on a left third molar (38) socket by filling it with a radiotransparent synthetic bone graft, mineralized collagen (MC). Photographic, X-ray and CBCT images were captured before and 3, 6 and 12 months after surgery. A new method was developed to standardize CBCT for quantitative evaluation. Obtained CBCT images showed good comparability. The post-extraction alveolar width and height were both over 95% of the original values, but some resorption of the lingual bone wall (>50%) and inter-crestal bone (>30%). It is concluded that an effective positional standardization method was developed for CBCT assessment of AR dimensional changes in the posterior mandible. The use of MC in combination with a collagen membrane improved dimensional preservation of the AR.

A novel combination of nano-scaffolds with micro-scaffolds to mimic extracellularmatrices improve osteogenesis.

To improve bone engineering for clinical applications, we coupled nanofiber-peptide hydrogel to nano-hydroxyapatite/collagen to form a bioactive scaffold (cnHAC) that mimics extracellular matrices. In comparison to nano-hydroxyapatite/collagen, we found that cnHAC promoted cell adhesion and spreading, and DNA content measurements, alkaline phosphatase activity assays, and reverse transcriptase-polymerase chain reaction analyses of osteogenic gene expression showed that cnHAC significantly improved cellular attachment, proliferation, and osteogenic differentiation in vitro (P < 0.05). In vivo models based on rat calvarial implants showed that cnHAC significantly enhanced bone regeneration (P < 0.05). In conclusion, we demonstrated that novel cnHAC scaffolds could potentially facilitate future bone regenerative medicine.