Segmental bone tissue engineering by seeding osteoblast precursor cells into titanium mesh-coral composite scaffolds

Enamel matrix derivative (EMD) enhances the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs)

To investigate the EMD's capacity in BMSCs osteogenic differentiation. In vivo and in vitro, BMSCs were treated with EMD, scanning electron microscopy, and Alizarin Red staining were used to detect the changes in the osteogenic ability of BMSCs, and the proliferation ability of BMSCs was evaluated by CCK8. In addition, by adding xav939, a typical inhibitor of Wnt/β-catenin signaling pathway, the regulatory function of Wnt/β-catenin signaling was clarified. The results showed that EMD promote cell proliferation and 25 μg/ml EMD had the most significant effect. Cells inducing osteogenesis for 2 and 3 even 4 weeks, the cell staining is deeper in EMD treated group than that of the control (P < 0.05) by alizarin Red staining, suggesting more mineralization of BMSCs. In vivo implanting the titanium plate wrapped with 25 μg/ml EMD treated-BMSC film into nude mice for 8 weeks, more nodules were formed on the surface of the titanium plate than that the control (P < 0.05). HE showed that there is a little blue-violet immature bone-like tissue block. Besides, the expression of RUNX Family Transcription Factor 2 (Runx2), Osterix, Osteocalcin (OCN), collagen I (COLI), alkaline phosphatase (ALP) and β-catenin were inhibited in xav939 group (P < 0.05); Inversely, all were activated in EMD group (P < 0.05). In conclusion, EMD promoted the proliferation and osteogenic differentiation of BMSCs. EMD's function on BMSCs might be associated with the Wnt/β-catenin signaling pathway.

Is there a role of coral bone substitutes in bone repair?

Xenogeneic bone graft materials are an alternative to autologous bone grafting. Among such implants, coralline-derived bone grafts substitutes have a long track record as safe, biocompatible and osteoconductive graft materials. In this review, we present the available literature surrounding their use with special focus on the commercially available graft materials. Corals thanks to their chemical and structural characteristics similar to those of the human cancellous bone have shown great potential but clinical data presented to date is ambiguous with both positive and negative outcomes reported. Correct formulation and design of the graft to ensure adequate osteo-activity and resorption appear intrinsic to a successful outcome.

Maxillary Sinus Augmentation Combining Bio-Oss with the Bone Marrow Aspirate Concentrate: A Histomorphometric Study in Humans

Purpose. To investigate the regenerative results obtained with the association of bone marrow aspirate concentrate using the Bone Marrow Aspirate Concentrate (BMAC) method to a xenogeneic bone graft (Bio-Oss) in sinus floor elevation. Materials and Methods. Using a randomized controlled study design in eight consecutive patients (age of 55.4 ± 9.2 years), 16 sinus floor lift procedures were performed with Bio-Oss alone (control group, CG, n = 8) or combined with bone marrow aspirate concentrate obtained via the BMAC method (test group, TG, n = 8). Six months after the grafting procedures, bone biopsies were harvested during implant placement and were analyzed by histomorphometry. Results. Histomorphometric analysis revealed a significantly higher amount (p < 0.05) of vital mineralized tissue in TG when compared to the CG (55.15 ± 20.91% and 27.30 ± 5.55%, resp.). For nonvital mineralized tissue, TG presented a statistically higher level of Bio-Oss resorption (p < 0.05) when compared with the CG (6.32 ± 12.03% and 22.79 ± 9.60%, resp.). Both groups (TG and CG) showed no significantly different levels (p > 0.05) of nonmineralized tissue (38.53 ± 13.08% and 49.90 ± 7.64%, resp.). Conclusion. The use of bone marrow concentrate obtained by BMAC method increased bone formation in sinus lift procedures.

Distraction osteogenesis combined with tissue-engineered cartilage in the reconstruction of condylar osteochondral defect

PURPOSE

Surgical rehabilitation of condylar osteochondral defect remains a challenge for surgeons. The aim of this study was to explore the feasibility of combining distraction osteogenesis with tissue-engineered cartilage in the reconstruction of condylar osteochondral defect.

MATERIALS AND METHODS

A condylar defect model was established in 18 goats that were randomly divided into 2 groups: the experimental group and the control group. Mandibular ramus osteotomies were performed and distractors were implanted in all animals. The mixture of chondrocytes and Pluronic F-127 (Sigma-Aldrich, St Louis, MO) was injected on the notched surface of a transport disc in the experimental group, whereas a scaffold without cells was transplanted into the control group. After a 5-day latency period, distraction was activated at a rate of 0.5 mm twice per day for 15 days. The goats were killed at the end of the fourth, eighth, or twelfth week in the consolidation period. Specimens were harvested and macroscopic evaluation, as well as Masson trichrome and immunohistochemical staining, were performed to compare the results between the 2 groups.

RESULTS

Osteogenesis was found in all animals with no evidence of infection. Condyle-like structures were formed at the upper end of the transport segment in all animals. The neocondylar surface was covered with a layer of smooth lustrous fibrocartilage in the experimental group. Collagen was shown in the reparative tissue by Masson trichrome staining. Immunohistochemistry staining indicated that type II collagen was positive, whereas type I collagen was negative on the neocondylar surface in the experimental group. No cartilage-like tissue was seen, but fibrous tissue was identified at the bony surface in the control group. In the experimental group, immunofluorescent semiquantitative analysis showed that the positive rate of type II collagen was 1.62% ± 0.53% after the fourth week of consolidation, and it increased to 12.39% ± 3.27% after the twelfth week. There was a significant difference in the expression of type II collagen between the goats examined after the fourth week, and those examined after the twelfth week.

CONCLUSION

The combination of distraction osteogenesis with tissue-engineered cartilage is an ideal alternative in the reconstruction of condylar osteochondral defect. By use of this method, the simultaneous rehabilitation and regeneration of condylar bone and cartilage were achieved.

The differentiation of human adipose-derived stem cells (hASCs) into osteoblasts is promoted by low amplitude, high frequency vibration treatment

Several studies have demonstrated that tissue culture conditions influence the differentiation of human adipose-derived stem cells (hASCs). Recently, studies performed on SAOS-2 and bone marrow stromal cells (BMSCs) have shown the effectiveness of high frequency vibration treatment on cell differentiation to osteoblasts. The aim of this study was to evaluate the effects of low amplitude, high frequency vibrations on the differentiation of hASCs toward bone tissue. In view of this goal, hASCs were cultured in proliferative or osteogenic media and stimulated daily at 30Hz for 45min for 28days. The state of calcification of the extracellular matrix was determined using the alizarin assay, while the expression of extracellular matrix and associated mRNA was determined by ELISA assays and quantitative RT-PCR (qRT-PCR). The results showed the osteogenic effect of high frequency vibration treatment in the early stages of hASC differentiation (after 14 and 21days). On the contrary, no additional significant differences were observed after 28days cell culture. Transmission Electron Microscopy (TEM) images performed on 21day samples showed evidence of structured collagen fibers in the treated samples. All together, these results demonstrate the effectiveness of high frequency vibration treatment on hASC differentiation toward osteoblasts.

Basic fibroblast growth factor enhances osteogenic and chondrogenic differentiation of human bone marrow mesenchymal stem cells in coral scaffold constructs

Temporomandibular joint (TMJ) disorders are commonly occurring degenerative joint diseases that require surgical replacement of the mandibular condyle in severe cases. Transplantation of tissue-engineered mandibular condyle constructs may solve some of the current surgical limitations to TMJ repair. We evaluated the feasibility of mandibular condyle constructs engineered from human bone marrow-derived mesenchymal cells (BMSCs). Specifically, human BMSCs were transfected with basic FGF (bFGF) gene-encoding plasmids and induced to differentiate into osteoblasts and chondroblasts. The cells were seeded onto mandibular condyle-shaped porous coral scaffolds and evaluated for osteogenic/chondrogenic differentiation, cell proliferation, collagen deposition and tissue vascularization. Transfected human BMSCs expressed bFGF and were highly proliferative. Osteogenesis was irregular, showing neovascularization around new bone tissue. There was no evidence of bilayered osteochondral tissue present in normal articulating surfaces. Collagen deposition, characteristic of bone and cartilage, was observed. Subcutaneous transplantation of seeded coral/hydrogel hyaluran constructs into nude mice resulted in bone formation and collagen type I and type II deposition. Neovascularization was observed around newly formed bone tissue; bFGF expression was detected in implanted constructs seeded with bFGF expressing hBMSCs. This report demonstrates that engineered porous coral constructs using bFGF gene-transfected human BMSCs may be a feasible option for surgical transplantation in TMJ repair.

In vitro and in vivo osteogenesis of porcine skin-derived mesenchymal stem cell-like cells with a demineralized bone and fibrin glue scaffold

In vitro and in vivo osteogenesis of skin-derived mesenchymal stem cell-like cells (SDMSCs) with a demineralized bone (DMB) and fibrin glue scaffold were compared. SDMSCs isolated from the ears of adult miniature pigs were evaluated for the expression of transcriptional factors (Oct-4, Sox-2, and Nanog) and MSC marker proteins (CD29, CD44, CD90, and vimentin). The isolated SDMSCs were cocultured in vitro with a mixed DMB and fibrin glue scaffold in a nonosteogenic medium for 1, 2, and 4 weeks. Osteonectin, osteocalcin, and Runx2 were expressed during the culture period and reached maximum at 2 weeks after in vitro coculture. von Kossa-positive bone minerals were also noted in the cocultured medium at 4 weeks. Autogenous porcine SDMSCs (1 x 10(7)) labeled with a tracking dye, PKH26, were grafted into the maxillary sinus with a DMB and fibrin glue scaffold. In the contralateral side, only a scaffold was grafted without SDMSCs (control). In vivo osteogenesis was evaluated from two animals euthanized at 2 and 4 weeks after grafting. In vivo PKH26 staining was detected in all the specimens at both time points. Trabecular bone formation and osteocalcin expression were more pronounced around the grafted materials in the SDMSC-grafted group compared with the control group. New bone generation was initiated from the periphery to the center of the grafted material. The number of proliferating cells increased over time and reached a peak at 4 weeks in both in vivo and in vitro specimens. These findings suggest that autogenous SDMSC grafting with a DMB and fibrin glue scaffold can serve as a predictable alternative to bone grafting in the maxillary sinus floor.

Ectopic Bone Formation from Mandibular Osteoblasts Cultured in a Novel Human Serum-derived Albumin Scaffold

The aim of this study was to evaluate the ectopic bone formation using a novel serum-derived albumin scaffold and cultured human mandibular osteoblasts in nude mice. Osteoblasts were cultured with 10% human serum and plated in a novel spongy noncalcified protein scaffold prepared with plasmatic albumin crossed with a glutaraldehyde type agent. Hematoxylin-eosin staining revealed a bone-like extracellular matrix and in vitro mineralization was confirmed by von Kossa staining. Histological and immunohistochemical evaluation showed progression of mineralization in vivo. These results suggest the clinical feasibility of alveolar cells and albumin scaffold as a good alternative for bone regeneration.

Metallic Scaffolds for Bone Regeneration

Bone tissue engineering is an emerging interdisciplinary field in Science, combining expertise in medicine, material science and biomechanics. Hard tissue engineering research is focused mainly in two areas, osteo and dental clinical applications. There is a lot of exciting research being performed worldwide in developing novel scaffolds for tissue engineering. Although, nowadays the majority of the research effort is in the development of scaffolds for non-load bearing applications, primarily using soft natural or synthetic polymers or natural scaffolds for soft tissue engineering; metallic scaffolds aimed for hard tissue engineering have been also the subject of in vitro and in vivo research and industrial development. In this article, descriptions of the different manufacturing technologies available to fabricate metallic scaffolds and a compilation of the reported biocompatibility of the currently developed metallic scaffolds have been performed. Finally, we highlight the positive aspects and the remaining problems that will drive future research in metallic constructs aimed for the reconstruction and repair of bone.