Mandibular repair in rats with premineralized silk scaffolds and BMP-2-modified bMSCs

Effect of tetrahedral DNA nanostructures on proliferation and osteo/odontogenic differentiation of dental pulp stem cells via activation of the notch signaling pathway

Dental pulp stem cells (DPSCs) derived from the human dental pulp tissue have multiple differentiation capabilities, such as osteo/odontogenic differentiation. Therefore, DPSCs are deemed as ideal stem cell sources for tissue regeneration. As new nanomaterials based on DNA, tetrahedral DNA nanostructures (TDNs) have tremendous potential for biomedical applications. Here, the authors aimed to explore the part played by TDNs in proliferation and osteo/odontogenic differentiation of DPSCs, and attempted to investigate if these cellular responses could be driven by activating the canonical Notch signaling pathway. Upon exposure to TDNs, proliferation and osteo/odontogenic differentiation of DPSCs were dramatically enhanced, accompanied by up regulation of Notch signaling. In general, our study suggested that TDNs can significantly promote proliferation and osteo/odontogenic differentiation of DPSCs, and this remarkable discovery can be applied in tissue engineering and regenerative medicine to develop a significant and novel method for bone and dental tissue regeneration.

MicroRNA-99a is a novel regulator of KDM6B-mediated osteogenic differentiation of BMSCs

Skeletal tissue originates from mesenchymal stem cells (MSCs) with differentiation potential into the osteoblast lineage regulated by essential transcriptional and post‐transcriptional mechanisms. Recently, miRNAs and histone modifications have been identified as novel key regulators of osteogenic differentiation of MSCs. Here, we identified miR‐99a and its target lysine (K)‐specific demethylase 6B (KDM6B) gene as novel modulators of osteogenic differentiation of bone mesenchymal stem cells (BMSCs). Microarray profiling and further validation by quantitative real‐time RT‐PCR revealed that miR‐99a was up‐regulated during osteoblastic differentiation of BMSCs, and decreased in differentiated osteoblasts. Transfection of miR‐99a mimics inhibited osteoblastic commitment and differentiation of BMSCs, whereas inhibition of miR‐99a by inhibitors enhances these processes. KDM6B was determined as one of important targets of miR‐99a, which was further confirmed by luciferase assay of 3′‐UTR of KDM6B. Moreover, HOX gene level decreased after transfection of miR‐99a mimics in BMSCs, which indicated that KDM6B is a bona fide target of miR‐99a. Furthermore, in a model of in vivo bone regeneration, osteoblast‐specific gain‐ and loss‐of‐function experiments performed using cranial bone defects revealed that miR‐99a mimics‐transfected BMSCs reduced bone formation, and conversely, miR‐99a inhibitors‐transfected BMSCs increased in vivo bone formation. Tissue‐specific inhibition of miR‐99a may be a potential novel therapeutic approach for enhancing BMSCs‐based bone formation and regeneration.

Silk Fibroin-Based Scaffold for Bone Tissue Engineering

Regeneration of diseased or damaged skeletal tissues is one of the challenge that needs to be solved. Although there have been many bone tissue engineering developed, scaffold-based tissue engineering complement the conventional treatment for large bone by completing biological and functional environment. Among many materials, silk fibroin (SF) is one of the favorable material for applications in bone tissue engineering scaffolding. SF is a fibrous protein mainly extracted from Bombyx mori. and spiders. SF has been used as a biomaterial for bone graft by its unique mechanical properties, controllable biodegradation rate and high biocompatibility. Moreover, SF can be processed using conventional and advanced biofabrication methods to form various scaffold types such as sponges, mats, hydrogels and films. This review discusses about recent application and advancement of SF as a biomaterial.

Advances in Protein-Based Materials: From Origin to Novel Biomaterials

Biomaterials play a very important role in biomedicine and tissue engineering where they directly affect the cellular activities and their microenvironment . Myriad of techniques have been employed to fabricate a vast number natural, artificial and recombinant polymer s in order to harness these biomaterials in tissue regene ration , drug delivery and various other applications. Despite of tremendous efforts made in this field during last few decades, advanced and new generation biomaterials are still lacking. Protein based biomaterials have emerged as an attractive alternatives due to their intrinsic properties like cell to cell interaction , structural support and cellular communications. Several protein based biomaterials like, collagen , keratin , elastin , silk protein and more recently recombinant protein s are being utilized in a number of biomedical and biotechnological processes. These protein-based biomaterials have enormous capabilities, which can completely revolutionize the biomaterial world. In this review, we address an up-to date review on the novel, protein-based biomaterials used for biomedical field including tissue engineering, medical science, regenerative medicine as well as drug delivery. Further, we have also emphasized the novel fabrication techniques associated with protein-based materials and implication of these biomaterials in the domain of biomedical engineering .

In vivo evaluation of modified silk fibroin scaffolds with a mimicked microenvironment of fibronectin/decellularized pulp tissue for maxillofacial surgery

This study aimed to carry out in vivo testing of the formation of new bone by modified silk fibroin scaffolds with a mimicked microenvironment of fibronectin/decellularized pulp in bone defects. Silk fibroin scaffolds were fabricated into three-dimensional scaffolds before being coated with fibronectin/decellularized pulp. The coated scaffolds were implanted into rabbits. Twenty-four bicortical calvarial defects in 12 rabbits were divided randomly into two groups: non-coated and coated silk fibroin scaffolds. The rabbits were sacrificed 2, 4 and 8 weeks after operation for evaluation of new bone formation. The morphology of the scaffolds, new bone formation and histology were evaluated by scanning electron microscopy, micro-CT and hematoxylin and eosin staining, respectively. The results showed that the coated silk fibroin scaffolds had a fibrillar network and crystal particles in the porous structure. The coated silk fibroin scaffolds demonstrated the ability to induce the formation of new bone with low inflammation and high vascularization. The results indicated that the modified silk fibroin scaffolds showed suitable biological performance and promise for bone regeneration in maxillofacial surgery.

Silk scaffolds in bone tissue engineering: An overview

Bone tissue plays multiple roles in our day-to-day functionality. The frequency of accidental bone damage and disorder is increasing worldwide. Moreover, as the world population continues to grow, the percentage of the elderly population continues to grow, which results in an increased number of bone degenerative diseases. This increased elderly population pushes the need for artificial bone implants that specifically employ biocompatible materials. A vast body of literature is available on the use of silk in bone tissue engineering. The current work presents an overview of this literature from materials and fabrication perspective. As silk is an easy-to-process biopolymer; this allows silk-based biomaterials to be molded into diverse forms and architectures, which further affects the degradability. This makes silk-based scaffolds suitable for treating a variety of bone reconstruction and regeneration objectives. Silk surfaces offer active sites that aid the mineralization and/or bonding of bioactive molecules that facilitate bone regeneration. Silk has also been blended with a variety of polymers and minerals to enhance its advantageous properties or introduce new ones. Several successful works, both in vitro and in vivo, have been reported using silk-based scaffolds to regenerate bone tissues or other parts of the skeletal system such as cartilage and ligament. A growing trend is observed toward the use of mineralized and nanofibrous scaffolds along with the development of technology that allows to control scaffold architecture, its biodegradability and the sustained releasing property of scaffolds. Further development of silk-based scaffolds for bone tissue engineering, taking them up to and beyond the stage of human trials, is hoped to be achieved in the near future through a cross-disciplinary coalition of tissue engineers, material scientists and manufacturing engineers.

STATEMENT OF SIGNIFICANCE

The state-of-art of silk biomaterials in bone tissue engineering, covering their wide applications as cell scaffolding matrices to micro-nano carriers for delivering bone growth factors and therapeutic molecules to diseased or damaged sites to facilitate bone regeneration, is emphasized here. The review rationalizes that the choice of silk protein as a biomaterial is not only because of its natural polymeric nature, mechanical robustness, flexibility and wide range of cell compatibility but also because of its ability to template the growth of hydroxyapatite, the chief inorganic component of bone mineral matrix, resulting in improved osteointegration. The discussion extends to the role of inorganic ions such as Si and Ca as matrix components in combination with silk to influence bone regrowth. The effect of ions or growth factor-loaded vehicle incorporation into regenerative matrix, nanotopography is also considered.

Evaluation of synergistic osteogenesis between icariin and BMP2 through a micro/meso hierarchical porous delivery system

BMP2 is well known as an outstanding growth factor for inducing new bone formation. However, improvements are still required to use BMP2 effectively and expand its clinical application due to the potential side effects at high doses. In this study, icariin (IC), a type of traditional Chinese medicine, was originally proposed to be a cooperative factor for BMP2. An alkaline phosphatase (ALP) activity assay showed that IC promoted BMP2 osteogenesis in a concentration-dependent manner with significant enhancement at 38.4 µM versus that for BMP2 at 0.8 µg/mL. Furthermore, we developed a composite hierarchical porous scaffold (SF/SBA15; composed of micropores of silk fibroin [SF] scaffold and mesopores of SBA15) for the controlled delivery of BMP2 and IC. This composite scaffold was investigated by a series of physical characterizations and displayed good in vitro cell biocompatibility. In addition, the composite scaffold also showed the degradation rate of 12% dry weight loss and a slight change in the microstructures within 10 days. Moreover, BMP2 and IC were loaded into the SF and SBA15 structures, respectively, of the SF/SBA15 scaffold. This protein/drug loading system (SFBMP2/SBA15IC) provided delivery of BMP2 with an initial burst release of 60.9%±0.9% in the first 24 hours and a gradual release over the subsequent 6 days to 97.9%±0.8%, whereas IC exhibited a burst release of 64.2%±0.7% in the first 24 hours, followed by a sustained release to 92.4%±0.8% over 10 days. With the prolonged local retention and interaction duration of BMP2 and IC, the SFBMP2/SBA15IC scaffold provided better osteogenic differentiation than other groups with different loading modes of BMP2 or IC, as determined by ALP staining and quantitation and Alizarin red staining. Finally, the results of quantitative real-time polymerase chain reaction analysis indicated that the SFBMP2/SBA15IC scaffold induced a significantly higher increase in the RUNX2, ALP, COL I, and OCN expression levels of cocultured bone marrow mesenchymal stem cells than other payload composite scaffolds. This study suggests that a micro/meso hierarchical porous delivery system of BMP2 and IC ensures osteogenic synergy and demonstrates promise for bone tissue engineering.

Alveolar bone tissue engineering in critical-size defects of experimental animal models: a systematic review and meta-analysis

Regeneration of large, 'critical-size' bone defects remains a clinical challenge. Bone tissue engineering (BTE) is emerging as a promising alternative to autogenous, allogeneic and biomaterial-based bone grafting. The objective of this systematic review was to answer the focused question: in animal models, do cell-based BTE strategies enhance regeneration in alveolar bone critical-size defects (CSDs), compared with grafting with only biomaterial scaffolds or autogenous bone? Following PRISMA guidelines, electronic databases were searched for controlled animal studies reporting maxillary or mandibular CSD and implantation of mesenchymal stem cells (MSCs) or osteoblasts (OBs) seeded on biomaterial scaffolds. A random effects meta-analysis was performed for the outcome histomorphometric new bone formation (%NBF). Thirty-six studies were included that reported on large- (monkeys, dogs, sheep, minipigs) and small-animal (rabbits, rats) models. On average, studies presented with an unclear-to-high risk of bias and short observation times. In most studies, MSCs or OBs were used in combination with alloplastic mineral-phase scaffolds. In five studies, cells were modified by ex vivo gene transfer of bone morphogenetic proteins (BMPs). The meta-analysis indicated statistically significant benefits in favour of: (1) cell-loaded vs. cell-free scaffolds [weighted mean difference (WMD) 15.59-49.15% and 8.60-13.85% NBF in large- and small-animal models, respectively]; and (2) BMP-gene-modified vs. unmodified cells (WMD 10.06-20.83% NBF in small-animal models). Results of cell-loaded scaffolds vs. autogenous bone were inconclusive. Overall, heterogeneity in the meta-analysis was high (I2  > 90%). In summary, alveolar bone regeneration is enhanced by addition of osteogenic cells to biomaterial scaffolds. The direction and estimates of treatment effect are useful to predict therapeutic efficacy and guide future clinical trials of BTE. Copyright © 2016 John Wiley & Sons, Ltd.

The synergistic effects of Sr and Si bioactive ions on osteogenesis, osteoclastogenesis and angiogenesis for osteoporotic bone regeneration

Bioactive ions released from bioceramics play important roles in bone regeneration; however, it is unclear how each ionic composition in complex bioceramics exerts its specific effect on bone regeneration. The aim of this study is to elucidate the functional effects of Sr and Si ions in bioceramics on the regeneration of osteoporotic bone. A model bioceramic with Sr- and Si-containing components (SMS) was successfully fabricated and the effects of ionic products from SMS bioceramics on the osteogenic, osteoclastic and angiogenic differentiation of rBMSCs-OVX and RANKL-induced osteoclasts were investigated. The results showed that SMS bioceramics could enhance ALP activity and expression of Col 1, OCN, Runx2, and angiogenic factors including VEGF and Ang-1. SMS bioceramics not only rebalanced the OPG/RANKL ratio of rBMSCs-OVX at early stage, but also repressed RANKL-induced osteoclast formation and expression of TRAP, DC-STAMP, V-ATPase a3, and NFATc1. The synergistic effects of Sr and Si ions were further investigated as compared with those of similar concentrations of Sr and Si ions alone. Sr and Si ions possessed synergistic effects on osteogenesis, osteoclastogenesis, and angiogenesis, attributed to the dominant effects of Sr ions on enhancing angiogenesis and repressing osteoclastogenesis, and the dominant effects of Si ions on stimulating osteogenesis. The in vivo study using critical-size mandibular defects of OVX rat models showed that SMS bioceramics could significantly enhance bone formation and mineralization compared with β-TCP bioceramics. Our results are the first to elucidate the specific effect of each ion from bioceramics on osteogenesis, osteoclastogenesis and angiogenesis for osteoporotic bone regeneration, paving the way for the design of functional biomaterials with complex compositions for tissue engineering and regenerative medicine.

STATEMENT OF SIGNIFICANCE

Bioactive ions released from bioceramics play important roles for bone regeneration; however, it is unclear how each of ionic compositions in complex bioceramics exerts its specific effect on bone regeneration. The aim of present study is to elucidate the functional effects of Sr and Si ions in complex bioceramics on the regeneration of osteoporotic bone. A model bioceramic with Sr and Si-containing components (SMS) was successfully fabricated and the effects of ionic products from SMS bioceramics on the osteogenic, osteoclastic and angiogenic differentiation of rBMSCs-OVX and RANKL-induced osteoclasts were investigated. The results showed that SMS bioceramics could enhance ALP activity and expression of Col 1, OCN, Runx2 and angiogenic factors including VEGF and Ang-1. SMS bioceramics not only rebalanced the ratio of OPG/RANKL of OVX-BMSCs at early stage, but also repressed RANKL-induced osteoclast formation and expression of TRAP, DC-STAMP, V-ATPase a3, and NFATc1. The synergistic effects of Sr and Si ions were further investigated as compared with the similar concentration of Sr and Si ions alone. It was found that Sr and Si ions possessed synergistic effects on osteogenesis, osteoclastogenesis and angiogenesis, attributed to the dominant effects of Sr ions on enhancing angiogenesis and repressing osteoclastogenesis, and the dominant effects of Si ions on stimulating osteogenesis. The in vivo study using critical-size mandibular defects of OVX rat models showed that SMS bioceramics could significantly enhance bone formation and mineralization as compared with β-TCP bioceramics. It is suggested that SMS bioceramics may be a promising biomaterial for osteoporotic bone regeneration. To our knowledge, this is the first time to elucidate the specific effect of each ion from bioceramics on osteogenesis, osteoclastogenesis and angiogenesis for osteoporotic bone regeneration, paving the way to design functional biomaterials with complex compositions for tissue engineering and regenerative medicine.

Stromal Cell-Derived Factor-1 Accelerates Cartilage Defect Repairing by Recruiting Bone Marrow Mesenchymal Stem Cells and Promoting Chondrogenic Differentiation<sup/>

Chemokine stromal cell-derived factor-1 (SDF-1) is a powerful chemoattractant for the localization of CXCR4-positive bone marrow mesenchymal stem cells (BMSCs) into the bone marrow. We studied the effects of SDF-1 on the cartilage defect repair by recruiting BMSCs and promoting its chondrogenic differentiation in vitro and in vivo. Chemotaxis analysis with Transwell plate showed that SDF-1 could recruit BMSCs through SDF-1/CXCR4 axis. Real-time polymerase chain reaction, enzyme-linked immunosorbent assays, and Western blot results suggested that the levels of type II collagen and GAG were increased after incubating BMSCs with SDF-1 compared with the without SDF-1 group. More positive BrdU-labeled BMSCs were detected at the cartilage defect region in the SDF-1 + poly [lactide-co-glycolide] (PLGA) scaffold group (SP) in which those animals showed a smooth and transparent cartilage tissue with a strong staining of toluidine blue and type II collagen compared with the no-SDF-1 groups. ICRS score suggested that the repair effect in the SDF-1 + PLGA-treated animals was improved compared with PLGA scaffold group alone at 4 and 8 weeks after surgery; the repair effect from the SDF + PLGA-treated animals was significantly improved compared with the PLGA alone at 12 weeks after surgery. Our in vitro and in vivo results indicated the following: (1) SDF-1 could recruit the BMSCs into cartilage defect area. (2) SDF-1 induces BMSCs expressing type II collagen and GAG, which may accelerate the BMSCs transforming into chondrocytes under the cartilage microenvironment in vivo. (3) PLGA scaffold attached with SDF-1 remarkably promoted the cartilage defect repairing. The defected cartilage was filled with transparent cartilage 12 weeks after the surgery, which shared a similar structure with the adjacent normal cartilage. Taken together, this research provides a new strategy for cartilage defect repairing.

Growth differentiation factor 15 promotes blood vessel growth by stimulating cell cycle progression in repair of critical-sized calvarial defect

Repair of large bone defects remains a challenge for surgeons, tissue engineering represents a promising approach. However, the use of this technique is limited by delayed vascularization in central regions of the scaffold. Growth differentiation factor 15(GDF15) has recently been reported to be a potential angiogenic cytokine and has an ability to promote the proliferation of human umbilical vein endothelial cells(HUVECs). Whether it can be applied for promoting vascularized bone regeneration is still unknown. In this study, we demonstrated that GDF15 augmented the expression of cyclins D1 and E, induced Rb phosphorylation and E2F-1 nuclear translocation, as well as increased HUVECs proliferation. Furthermore, we also observed that GDF15 promoted the formation of functional vessels at an artificially-induced angiogenic site, and remarkably improved the healing in the repair of critical-sized calvarial defects. Our results confirm the essential role of GDF15 in angiogenesis and suggest its potential beneficial use in regenerative medicine.

Force-induced increased osteogenesis enables accelerated orthodontic tooth movement in ovariectomized rats

As the number of elderly orthodontic patients increases, the impact of postmenopausal osteoporosis on orthodontic tooth movement (OTM) has attracted a great deal of attention because OTM relies on alveolar bone remodeling. The question of whether OTM causes subsequent alveolar bone loss and is harmful to alveolar bone health under osteoporotic conditions remains to be answered. The present study aimed to clarify the influences of OTM on alveolar bone in osteoporotic rats. OTM was accelerated in ovariectomized (OVX) rats as a result of increased bone resorption in the pressure area. At the same time, anabolic bone formation was promoted in the tension area during OTM in OVX rats. Micro-CT analysis of alveolar bone revealed a decrease in BMD, BV/TV and Tb.Th. in the OTM group compared with that in non-OTM rats on day 21 of OTM, suggesting that OTM caused alveolar bone loss in OVX rats during OTM. However, the OTM-induced bone loss could be recovered 3 months after OTM in OVX rats. Thus, our findings suggest that increased osteogenesis may compensate for the increased bone resorption during and after OTM and enable effective accelerated OTM in OVX rats.

Effect of tetrahedral DNA nanostructures on osteogenic differentiation of mesenchymal stem cells via activation of the Wnt/β-catenin signaling pathway

Adipose-derived stem cells (ADSCs) are considered to be ideal stem cell sources for bone regeneration owing to their ability to differentiate into osteo-like cells. Therefore, they have attracted increasing attention in recent years. Tetrahedral DNA nanostructures (TDNs), a new type of DNA-based biomaterials, have shown great potential for biomedical applications. In the present work, we aimed to investigate the role played by TDNs in osteogenic differentiation and proliferation of ADSCs and tried to explore if the canonical Wnt signal pathway could be the vital biological mechanism driving these cellular responses. Upon exposure to TDNs, ADSCs proliferation and osteogenic differentiation were significantly enhanced, accompanied by the up-regulation of genes correlated with the Wnt/β-catenin pathway. In conclusion, our results indicate that TDNs are crucial regulators of the increase in osteogenic potential and ADSCs proliferation, and this noteworthy discovery could provide a promising novel approach toward ADSCs-based bone defect regeneration.

Nanophase bone substitute for craniofacial load bearing application: Pilot study in the rodent

An exploratory pilot study shows that a rodent mandibular defect model is useful in determining the biological response to a nanophase collagen/apatite composite designed as a biomimetic load-bearing bone substitute. Using a critical size defect, eight groups of rats (n = 3) were implanted with four renditions of the nanophase bone substitute (NBS) biomaterial. Each rendition was tested with and without recombinant human bone morphogenetic protein 2 (BMP2). NBS biomaterial renditions were: baseline, hyper-densified, d-ribose crosslinked, and d-ribose crosslinked and hyper-densified. Biological outcomes were assessed surgically, radiologically, and histologically. With the limited power available due to the small N's involved, some interesting hypotheses were generated that will be more fully investigated in future studies. BMP2 loaded NBS, when uncrosslinked, resulted in robust bone formation in the entire defect volume (regardless of porosity). Unloaded NBS were well tolerated but did not cause significant new bone formation in the defect volume. Densification alone had little effect on in vivo performance. Crosslinking thwarted implant uptake of BMP2 and resulted in fibrous encapsulation. It is concluded that the nanophase bone substitute is well tolerated in this bone defect model. When loaded with BMP2, implantation resulted in complete bony healing and defect closure with implant density (porosity) having little effect on bone healing or remodeling. Without BMP2 the biomaterial did not result in defect closure. Crosslinking, necessary to increase mechanical properties in an aqueous environment, disrupts osteointegration and BMP2 uptake. Alternate implant fabrication strategies will be necessary to achieve an improved balance between material strength and osteointegration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 520-532, 2018.

The enhancement of osteogenic capacity in a synthetic BMP-2 derived peptide coated mineralized collagen composite in the treatment of the mandibular defects

The novel synthetic peptide P17-BMP-2 could promote cell attachment and enhance osteogenic capability. A composite, comprising nano-hydroxyapatite, collagen and poly(L-lactide) (nHAC/PLLA), was an efficient scaffold for carrier of P17-BMP-2. Our aim was to investigate whether nHAC/PLLA/P17-BMP-2 accelerates the osteogenesis as a reliable method for mandibular defect healing in this study. The repair capability was assessed by the gross observation, X-ray test and histological observation in four animal experiment groups at 2 week and 4 week after surgery: Group A (control), Group B (nHAC/PLLA treatment), Group C (nHAC/PLLA with 2 mg/g P17-BMP-2 treatment) and Group D (nHAC/PLLA with 10 mg/g P17-BMP-2 treatment). The Lane-Sandhu X-ray scores of the four groups were compared among four groups as well. The results showed that the composites containing the highest content of P17- BMP-2 performed best. Therefore, the nHAC/PLLA with P17-BMP-2 composite can accelerate the osteogenesis for mandibular defect healing and could be an ideal biological material as a bone graft material option for clinical applications.

Modification of a SLA titanium surface with calcium-containing nanosheets and its effects on osteoblast behavior

The aim of this study was to present a procedure to prepare a calcium-containing nanosheets-modified sandblasted and acid etched (SLA) titanium surface and explore its effects on osteoblast behavior.

Gene Therapy for Bone Defects in Oral and Maxillofacial Surgery: A Systematic Review and Meta-Analysis of Animal Studies

Craniofacial bone defects are challenging problems for maxillofacial surgeons over the years. With the development of cell and molecular biology, gene therapy is a breaking new technology with the aim of regenerating tissues by acting as a delivery system for therapeutic genes in the craniofacial region rather than treating genetic disorders. A systematic review was conducted summarizing the articles reporting gene therapy in maxillofacial surgery to answer the question: Was gene therapy successfully applied to regenerate bone in the maxillofacial region? Electronic searching of online databases was performed in addition to hand searching of the references of included articles. No language or time restrictions were enforced. Meta-analysis was done to assess significant bone formation after delivery of gene material in the surgically induced maxillofacial defects. The search identified 2081 articles, of which 57 were included with 1726 animals. Bone morphogenetic proteins were commonly used proteins for gene therapy. Viral vectors were the universally used vectors. Sprague-Dawley rats were the frequently used animal model in experimental studies. The quality of the articles ranged from excellent to average. Meta-analysis results performed on 21 articles showed that defects favored bone formation by gene therapy. Funnel plot showed symmetry with the absence of publication bias. Gene therapy is on the top list of innovative strategies that developed in the last 10 years with the hope of developing a simple chair-side protocol in the near future, combining improvement of gene delivery as well as knowledge of the molecular basis of oral and maxillofacial structures.

Micro-CT vs. Whole Body Multirow Detector CT for Analysing Bone Regeneration in an Animal Model

OBJECTIVES

Compared with multirow detector CT (MDCT), specimen (ex vivo) micro-CT (μCT) has a significantly higher (~ 30 x) spatial resolution and is considered the gold standard for assessing bone above the cellular level. However, it is expensive and time-consuming, and when applied in vivo, the radiation dose accumulates considerably. The aim of this study was to examine whether the lower resolution of the widely used MDCT is sufficient to qualitatively and quantitatively evaluate bone regeneration in rats.

METHODS

Forty critical-size defects (5mm) were placed in the mandibular angle of rats and covered with coated bioactive titanium implants to promote bone healing. Five time points were selected (7, 14, 28, 56 and 112 days). μCT and MDCT were used to evaluate the defect region to determine the bone volume (BV), tissue mineral density (TMD) and bone mineral content (BMC).

RESULTS

MDCT constantly achieved higher BV values than μCT (10.73±7.84 mm3 vs. 6.62±4.96 mm3, p<0.0001) and consistently lower TMD values (547.68±163.83 mm3 vs. 876.18±121.21 mm3, p<0.0001). No relevant difference was obtained for BMC (6.48±5.71 mm3 vs. 6.15±5.21 mm3, p = 0.40). BV and BMC showed very strong correlations between both methods, whereas TMD was only moderately correlated (r = 0.87, r = 0.90, r = 0.68, p < 0.0001).

CONCLUSIONS

Due to partial volume effects, MDCT overestimated BV and underestimated TMD but accurately determined BMC, even in small volumes, compared with μCT. Therefore, if bone quantity is a sufficient end point, a considerable number of animals and costs can be saved, and compared with in vivo μCT, the required dose of radiation can be reduced.

In quest of optimal drug-supported and targeted bone regeneration in the cranio facial area: a review of techniques and methods

Craniofacial bone structures are frequently and extensively affected by trauma, tumors, bone infections and diseases, age-related degeneration and atrophy, as well as congenital malformations and developmental anomalies. Consequently, severe encumbrances are imposed on both patients and healthcare systems due to the complex and lengthy treatment duration. The search for alternative methods to bone transplantation, grafting and the use of homologous or heterologous bone thus responds to one of the most significant problems in human medicine. This review focuses on the current consensus of bone-tissue engineering in the craniofacial area with emphasis on drug-induced stem cell differentiation and induced bone regeneration.

The use of SHP-2 gene transduced bone marrow mesenchymal stem cells to promote osteogenic differentiation and bone defect repair in rat

Bone tissue engineering is a promising approach for bone regeneration, in which growth factors play an important role. The tyrosine phosphatase Src-homology region 2-containing protein tyrosine phosphatase 2 (SHP2), encoded by the PTPN11 gene, is essential for the differentiation, proliferation and metabolism of osteoblasts. However, SHP-2 has never been systematically studied for its effect in osteogenesis. We predicted that overexpression of SHP-2 could promote bone marrow-derived mesenchymal stem cell (BMSC)osteogenic differentiation and SHP-2 transduced BMSCs could enhance new bone formation, determined using the following study groups: (1) BMSCs transduced with SHP-2 and induced with osteoblast-inducing liquid (BMSCs/SHP-2/OL); (2) BMSCs transduced with SHP-2 (BMSCs/-SHP-2); (3) BMSCs induced with osteoblast-inducing liquid (BMSCs/OL) and (4) pure BMSCs. Cells were assessed for osteogenic differentiation by quantitative real-time polymerase chain reaction analysis, western blot analysis, alkaline phosphatase activity and alizarin red S staining. For in vivo assessment, cells were combined with beta-tricalcium phosphate scaffolds and transplanted into rat calvarial defects for 8 weeks. Following euthanasia, skull samples were explanted for osteogenic evaluation, including micro-computed tomography measurement, histology and immunohistochemistry staining. SHP-2 and upregulation of its gene promoted BMSC osteogenic differentiation and therefore represents a potential new therapeutic approach to bone repair. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1871-1881, 2016.

Reosseointegration Following Regenerative Therapy of Tissue-Engineered Bone in a Canine Model of Experimental Peri-Implantitis

BACKGROUND

Due to the existence of inflammation and limited osteogenesis on the precontaminated implant surface, reosseointegration is difficult to realize by current therapies. Tissue-engineering strategy has been proved quite effective in intractable bone defect situation.

PURPOSE

This study was designed to see whether the adoption of tissue-engineered bone complex of adipose-derived stem cells (ASCs) and bone morphogenetic protein-2 (BMP-2) gene delivery would work efficiently in the correction of experimental peri-implantitis.

METHODS

All premolars in both side of mandibular were removed from six beagle canines three months before implant placement. Typical peri-implantitis were then induced by three month ligature placement. After the implementation of identical anti-bacterial and mechanical debridement therapy, the shaped peri-implant defect were stuffed with four groups of constructs, as A: beta tricalcium phosphate (β-TCP); B: β-TCP with ASCs; C: β-TCP with enhanced green fluorescent protein gene transduced ASCs (AdGFP-ASCs); and D: β-TCP with bone morphogenetic protein-2 gene-modified ASCs (AdBMP-2-ASCs). Systematic radiographic, micro-CT, and histomorphometrical assessments were performed.

RESULTS

After six months of healing, more bone formation and reosseointegration was found around the implant of groups B and C than group A. And group D further promoted the new bone height and reosseointegration percentage. Moreover, sequential fluorescence labeling tells that group D exhibited the quickest and strongest bone formation on the cleaned implant surface during the entire observation period as compared to the other three groups.

CONCLUSIONS

These data demonstrated that tissue engineered bone of ASCs, BMP-2 gene delivery, and β-TCP could exert powerful therapeutic effect on peri-implantitis as expected, which may suggest a feasible way to maintain the stability and masticatory function of dental implant.

Silk fibroin as biomaterial for bone tissue engineering

Silk fibroin (SF) is a fibrous protein which is produced mainly by silkworms and spiders. Its unique mechanical properties, tunable biodegradation rate and the ability to support the differentiation of mesenchymal stem cells along the osteogenic lineage, have made SF a favorable scaffold material for bone tissue engineering. SF can be processed into various scaffold forms, combined synergistically with other biomaterials to form composites and chemically modified, which provides an impressive toolbox and allows SF scaffolds to be tailored to specific applications. This review discusses and summarizes recent advancements in processing SF, focusing on different fabrication and functionalization methods and their application to grow bone tissue in vitro and in vivo. Potential areas for future research, current challenges, uncertainties and gaps in knowledge are highlighted.

STATEMENT OF SIGNIFICANCE

Silk fibroin is a natural biomaterial with remarkable biomedical and mechanical properties which make it favorable for a broad range of bone tissue engineering applications. It can be processed into different scaffold forms, combined synergistically with other biomaterials to form composites and chemically modified which provides a unique toolbox and allows silk fibroin scaffolds to be tailored to specific applications. This review discusses and summarizes recent advancements in processing silk fibroin, focusing on different fabrication and functionalization methods and their application to grow bone tissue in vitro and in vivo. Potential areas for future research, current challenges, uncertainties and gaps in knowledge are highlighted.

Enhanced osteogenic activity and anti-inflammatory properties of Lenti-BMP-2-loaded TiO₂ nanotube layers fabricated by lyophilization following trehalose addition

To enhance biocompatibility and osseointegration between titanium implants and surrounding bone tissue, numerous efforts have been made to modify the surface topography and composition of Ti implants. In this paper, Lenti-BMP-2-loaded TiO2 nanotube coatings were fabricated by lyophilization in the presence of trehalose to functionalize the surface. We characterized TiO2 nanotube layers in terms of the following: surface morphology; Lenti-BMP-2 and trehalose release; their ability to induce osteogenesis, proliferation, and anti-inflammation in vitro; and osseointegration in vivo. The anodized TiO2 nanotube surfaces exhibited an amorphous glassy matrix perpendicular to the Ti surface. Both Lenti-BMP-2 and trehalose showed sustained release over the course of 8 days. Results from real-time quantitative polymerase chain reaction studies demonstrated that lyophilized Lenti-BMP-2/TiO2 nanotubes constructed with trehalose (Lyo-Tre-Lenti-BMP-2) significantly promoted osteogenic differentiation of bone marrow stromal cells but not their proliferation. In addition, Lyo-Tre-Lenti-BMP-2 nanotubes effectively inhibited lipopolysaccharide-induced interleukin-1β and tumor necrosis factor-α production. In vivo, the formulation also promoted osseointegration. This study presents a promising new method for surface-modifying biomedical Ti-based implants to simultaneously enhance their osteogenic potential and anti-inflammatory properties, which can better satisfy clinical needs.

A review on carrier systems for bone morphogenetic protein-2

Bone morphogenetic protein-2 (BMP-2) has unique bone regeneration property. The powerful osteoinductive nature makes it considered as second line of therapy in nonunion bone defect. A large number of carriers and delivery systems made up of different materials have been investigated for controlled and sustained release of BMP-2. The delivery systems are in the form of hydrogel, microsphere, nanoparticles, and fibers. The carriers used for the delivery are made up of metals, ceramics, polymers, and composites. Implantation of these protein-loaded carrier leads to cell adhesion, degradation which eventually releases the drug/protein at site specific. But, problems like ectopic growth, lesser protein delivery, inactivation of the protein are reported in the available carrier systems. Therefore, it is need of an hour to modify the available carrier systems as well as explore other biomaterials with desired properties. In this review, all the reported carrier systems made of metals, ceramics, polymers, composites are evaluated in terms of their processing conditions, loading capacity and release pattern of BMP-2. Along with these biomaterials, the attempts of protein modification by adding some functional group to BMP-2 or extracting functional peptides from the protein to achieve the desired effect, is also evaluated. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 904-925, 2017.

Hierarchical micro/nanostructured titanium with balanced actions to bacterial and mammalian cells for dental implants

A versatile strategy to endow dental implants with long-term antibacterial ability without compromising the cytocompatibility is highly desirable to combat implant-related infection. Silver nanoparticles (Ag NPs) have been utilized as a highly effective and broad-spectrum antibacterial agent for surface modification of biomedical devices. However, the high mobility and subsequent hazardous effects of the particles on mammalian cells may limit its practical applications. Thus, Ag NPs were immobilized on the surface of sand-blasted, large grit, and acid-etched (SLA) titanium by manipulating the atomic-scale heating effect of silver plasma immersion ion implantation. The silver plasma immersion ion implantation-treated SLA surface gave rise to both good antibacterial activity and excellent compatibility with mammalian cells. The antibacterial activity rendered by the immobilized Ag NPs was assessed using Fusobacterium nucleatum and Staphylococcus aureus, commonly suspected pathogens for peri-implant disease. The immobilized Ag NPs offered a good defense against multiple cycles of bacteria attack in both F. nucleatum and S. aureus, and the mechanism was independent of silver release. F. nucleatum showed a higher susceptibility to Ag NPs than S. aureus, which might be explained by the presence of different wall structures. Moreover, the immobilized Ag NPs had no apparent toxic influence on the viability, proliferation, and differentiation of rat bone marrow mesenchymal stem cells. These results demonstrated that good bactericidal activity could be obtained with very small quantities of immobilized Ag NPs, which were not detrimental to the mammalian cells involved in the osseointegration process, and promising for titanium-based dental implants with commercial SLA surfaces.

Propofol promotes spinal cord injury repair by bone marrow mesenchymal stem cell transplantation

Propofol is a neuroprotective anesthetic. Whether propofol can promote spinal cord injury repair by bone marrow mesenchymal stem cells remains poorly understood. We used rats to investigate spinal cord injury repair using bone marrow mesenchymal stem cell transplantation combined with propofol administration via the tail vein. Rat spinal cord injury was clearly alleviated; a large number of newborn non-myelinated and myelinated nerve fibers appeared in the spinal cord, the numbers of CM-Dil-labeled bone marrow mesenchymal stem cells and fluorogold-labeled nerve fibers were increased and hindlimb motor function of spinal cord-injured rats was markedly improved. These improvements were more prominent in rats subjected to bone marrow mesenchymal cell transplantation combined with propofol administration than in rats receiving monotherapy. These results indicate that propofol can enhance the therapeutic effects of bone marrow mesenchymal stem cell transplantation on spinal cord injury in rats.

Minimally traumatic alveolar ridge augmentation with a tunnel injectable thermo-sensitive alginate scaffold

Injectable bone substitutes and techniques have been developed for use in minimally invasive procedures for bone augmentation.

Nanofibrous spongy microspheres enhance odontogenic differentiation of human dental pulp stem cells

Dentin regeneration is challenging due to its complicated anatomical structure and the shortage of odontoblasts. In this study, a novel injectable cell carrier, nanofibrous spongy microspheres (NF-SMS), is developed for dentin regeneration. Biodegradable and biocompatible poly(l-lactic acid)-block-poly(l-lysine) are synthesized and fabricated into NF-SMS using self-assembly and thermally induced phase separation techniques. It is hypothesized that NF-SMS with interconnected pores and nanofibers can enhance the proliferation and odontogenic differentiation of human dental pulp stem cells (hDPSCs), compared to nanofibrous microspheres (NF-MS) without pore structure and conventional solid microspheres (S-MS) with neither nanofibers nor pore structure. During the first 9 d in culture, hDPSCs proliferate significantly faster on NF-SMS than on NF-MS or S-MS (p < 0.05). Following in vitro odontogenic induction, all the examined odontogenic genes (alkaline phosphatase content, osteocalcin, bone sialoprotein, collagen 1, dentin sialophosphoprotein (DSPP)), calcium content, and DSPP protein content are found significantly higher in the NF-SMS group than in the control groups. Furthermore, 6 weeks after subcutaneous injection of hDPSCs and microspheres into nude mice, histological analysis shows that NF-SMS support superior dentin-like tissue formation compared to NF-MS or S-MS. Taken together, NF-SMS have great potential as an injectable cell carrier for dentin regeneration.

High-Fat Diet/Low-Dose Streptozotocin-Induced Type 2 Diabetes in Rats Impacts Osteogenesis and Wnt Signaling in Bone Marrow Stromal Cells

Bone regeneration disorders are a significant problem in patients with type 2 diabetes mellitus. Bone marrow stromal cells (BMSCs) are recognized as ideal seed cells for tissue engineering because they can stimulate osteogenesis during bone regeneration. Therefore, the aim of this study was to investigate the osteogenic potential of BMSCs derived from type 2 diabetic rats and the pathogenic characteristics of dysfunctional BMSCs that affect osteogenesis. BMSCs were isolated from normal and high-fat diet+streptozotocin-induced type 2 diabetic rats. Cell metabolic activity, alkaline phosphatase (ALP) activity, mineralization and osteogenic gene expression were reduced in the type 2 diabetic rat BMSCs. The expression levels of Wnt signaling genes, such as β-catenin, cyclin D1 and c-myc, were also significantly decreased in the type 2 diabetic rat BMSCs, but the expression of GSK3β remained unchanged. The derived BMSCs were cultured on calcium phosphate cement (CPC) scaffolds and placed subcutaneously into nude mice for eight weeks; they were detected at a low level in newly formed bone. The osteogenic potential of the type 2 diabetic rat BMSCs was not impaired by the culture environment, but it was impaired by inhibition of the Wnt signaling pathway, likely due to an insufficient accumulation of β-catenin rather than because of GSK3β stimulation. Using BMSCs derived from diabetic subjects could offer an alternative method of regenerating bone together with the use of supplementary growth factors to stimulate the Wnt signaling pathway.

Propofol injection combined with bone marrow mesenchymal stem cell transplantation better improves electrophysiological function in the hindlimb of rats with spinal cord injury than monotherapy

The repair effects of bone marrow mesenchymal stem cell transplantation on nervous system damage are not satisfactory. Propofol has been shown to protect against spinal cord injury. Therefore, this study sought to explore the therapeutic effects of their combination on spinal cord injury. Rat models of spinal cord injury were established using the weight drop method. Rats were subjected to bone marrow mesenchymal stem cell transplantation via tail vein injection and/or propofol injection via tail vein using an infusion pump. Four weeks after cell transplantation and/or propofol treatment, the cavity within the spinal cord was reduced. The numbers of PKH-26-positive cells and horseradish peroxidase-positive nerve fibers apparently increased in the spinal cord. Latencies of somatosensory evoked potentials and motor evoked potentials in the hindlimb were noticeably shortened, amplitude was increased and hindlimb motor function was obviously improved. Moreover, the combined effects were better than cell transplantation or propofol injection alone. The above data suggest that the combination of propofol injection and bone marrow mesenchymal stem cell transplantation can effectively improve hindlimb electrophysiological function, promote the recovery of motor funtion, and play a neuroprotective role in spinal cord injury in rats.

Human dental pulp stem cells: Applications in future regenerative medicine

Stem cells are pluripotent cells, having a property of differentiating into various types of cells of human body. Several studies have developed mesenchymal stem cells (MSCs) from various human tissues, peripheral blood and body fluids. These cells are then characterized by cellular and molecular markers to understand their specific phenotypes. Dental pulp stem cells (DPSCs) are having a MSCs phenotype and they are differentiated into neuron, cardiomyocytes, chondrocytes, osteoblasts, liver cells and β cells of islet of pancreas. Thus, DPSCs have shown great potentiality to use in regenerative medicine for treatment of various human diseases including dental related problems. These cells can also be developed into induced pluripotent stem cells by incorporation of pluripotency markers and use for regenerative therapies of various diseases. The DPSCs are derived from various dental tissues such as human exfoliated deciduous teeth, apical papilla, periodontal ligament and dental follicle tissue. This review will overview the information about isolation, cellular and molecular characterization and differentiation of DPSCs into various types of human cells and thus these cells have important applications in regenerative therapies for various diseases. This review will be most useful for postgraduate dental students as well as scientists working in the field of oral pathology and oral medicine.

Epigenetically Modified Bone Marrow Stromal Cells in Silk Scaffolds Promote Craniofacial Bone Repair and Wound Healing

Epigenetic regulation of gene expression is a central mechanism that governs cell stemness, determination, commitment, and differentiation. It has been recently found that PHF8, a major H4K20/H3K9 demethylase, plays a critical role in craniofacial and bone development. In this study, we hypothesize that PHF8 promotes osteoblastogenesis by epigenetically regulating the expression of a nuclear matrix protein, special AT-rich sequence-binding protein 2 (SATB2) that plays pivotal roles in skeletal patterning and osteoblast differentiation. Our results showed that expression levels of PHF8 and SATB2 in preosteoblasts and bone marrow stromal cells (BMSCs) increased simultaneously during osteogenic induction. Overexpressing PHF8 in these cells upregulated the expression of SATB2, Runx2, osterix, and bone matrix proteins. Conversely, knockdown of PHF8 reduced the expression of these genes. Furthermore, ChIP assays confirmed that PHF8 specifically bound to the transcription start site (TSS) of the SATB2 promoter, and the expression of H3K9me1 at the TSS region of SATB2 decreased in PHF8 overexpressed group. Implantation of the BMSCs overexpressing PHF8 with silk protein scaffolds promoted bone regeneration in critical-sized defects in mouse calvaria. Taken together, our results demonstrated that PHF8 epigenetically modulates SATB2 activity, triggering BMSCs osteogenic differentiation and facilitating bone formation and regeneration in biodegradable silk scaffolds.

The Effect of Quercetin on the Osteogenesic Differentiation and Angiogenic Factor Expression of Bone Marrow-Derived Mesenchymal Stem Cells

Bone marrow-derived mesenchymal stem cells (BMSCs) are widely used in regenerative medicine in light of their ability to differentiate along the chondrogenic and osteogenic lineages. As a type of traditional Chinese medicine, quercetin has been preliminarily reported to promote osteogenic differentiation in osteoblasts. In the present study, the effects of quercetin on the proliferation, viability, cellular morphology, osteogenic differentiation and angiogenic factor secretion of rat BMSCs (rBMSCs) were examined by MTT assay, fluorescence activated cell sorter (FACS) analysis, real-time quantitative PCR (RT-PCR) analysis, alkaline phosphatase (ALP) activity and calcium deposition assays, and Enzyme-linked immunosorbent assay (ELISA). Moreover, whether mitogen-activated protein kinase (MAPK) signaling pathways were involved in these processes was also explored. The results showed that quercetin significantly enhanced the cell proliferation, osteogenic differentiation and angiogenic factor secretion of rBMSCs in a dose-dependent manner, with a concentration of 2 μM achieving the greatest stimulatory effect. Moreover, the activation of the extracellular signal-regulated protein kinases (ERK) and p38 pathways was observed in quercetin-treated rBMSCs. Furthermore, these induction effects could be repressed by either the ERK inhibitor PD98059 or the p38 inhibitor SB202190, respectively. These data indicated that quercetin could promote the proliferation, osteogenic differentiation and angiogenic factor secretion of rBMSCs in vitro, partially through the ERK and p38 signaling pathways.

Roles of SATB2 in site-specific stemness, autophagy and senescence of bone marrow mesenchymal stem cells

Craniofacial bone marrow mesenchymal stem cells (BMSCs) display some site-specific properties that differ from those of BMSCs derived from the trunk and appendicular skeleton, but the characteristics of craniofacial BMSCs and the mechanisms that underlie their properties are not completely understood. Previous studies indicated that special AT-rich binding protein 2 (SATB2) may be a potential regulator of craniofacial skeletal patterning and site-specific osteogenic capacity. Here, we investigated the stemness, autophagy, and anti-aging capacity of mandible-derived BMSCs (M-BMSCs) and tibia-derived BMSCs (T-BMSCs) and explored the role of SATB2 in regulating these properties. M-BMSCs not only possessed stronger expression of SATB2 and stemness markers (pluripotency genes, such as Nanog, OCT-4, Sox2, and Nestin) but also exhibited stronger autophagy and anti-aging capacities under normal or hypoxia/serum deprivation conditions compared to T-BMSCs. Exogenous expression of SATB2 in T-BMSCs significantly enhanced the expression of pluripotency genes as well as autophagy and anti-aging capacity. Moreover, SATB2 markedly enhanced osteogenic differentiation of BMSCs in vitro, and promoted bone defect regeneration and the survival of BMSCs that were transplanted into mandibles with critical size defects. Mechanistically, SATB2 upregulates pluripotency genes and autophagy-related genes, which in turn activate the mechanistic target of rapamycin signaling pathway. Collectively, our results provide novel evidence that site-specific BMSCs have distinct biological properties and suggest that SATB2 plays a potential role in regulating the stemness, autophagy, and anti-aging properties of craniofacial BMSCs. The application of SATB2 to manipulate stem cells for the reconstruction of bone defects might represent a new approach.

Graphene film-functionalized germanium as a chemically stable, electrically conductive, and biologically active substrate

Depositing large-area graphene film by CVD in situ on a Ge semiconductor improves its corrosion resistance, electrical conductivity and biological activity.

Strontium delivery on topographical titanium to enhance bioactivity and osseointegration in osteoporotic rats

Strontium-substituted hierarchical Ti surface can enhance the osseointegration by both increasing new bone formation and reducing bone resorption under osteoporotic conditions.

Preparation of an rhBMP-2 loaded mesoporous bioactive glass/calcium phosphate cement porous composite scaffold for rapid bone tissue regeneration

An rhBMP-2/MBG/CPC scaffold is beneficial for rapid bone tissue regeneration in the early stage.

Transfection with follicular dendritic cell secreted protein to affect phenotype expression of human periodontal ligament cells

Follicular dendritic cell secreted protein (FDC-SP), has been found to inhibit osteogenic differentiation of human periodontal ligament cells (hPDLCs) in recent studies. Based on these findings, we further investigate its effect on phenotype expression of hPDLCs in the present study, aiming to contribute to a better understanding of the biological functions governing FDC-SP-induced hPDLC differentiation. hPDLCs were firstly identified with immunocytochemical staining, followed by transfection with FDC-SP lentiviral vector. Western blot analysis was used to confirm the expression of FDC-SP. Then the influence of FDC-SP transfection on hPDLC proliferation, osteogenic and fibrogenic phenotype expression was evaluated at the mRNA and protein level. Procollagen type I c-peptide production was measured and alizarin red staining was then conducted to demonstrate effect of FDC-SP on functional differentiation. We found that hPDLCs could be successfully transfected with FDC-SP. Cell proliferation and cell cycle tests indicated that transfection with FDC-SP did not affect hPDLC proliferation. Moreover, according to real-time PCR and Western blot results, expression levels of type 1 collagen alpha 1, type 1 collagen alpha 2 and type 3 collagen were upregulated while that of osteocalcin, osteopontin, and bone sialoprotein were downregulated in FDC-SP transfected cells. In addition, hPDLCs overexpressing FDC-SP exhibited higher PIP production than the controls. Our findings demonstrate that transfection with FDC-SP has negligible adverse effect on proliferation of hPDLCs and imply the biological function of FDC-SP as a fibroblastic phenotype stabilizer by inhibiting hPDLCs differentiation into mineralized tissue-forming cells, thus regulating regeneration in periodontal tissue engineering.

Dental pulp cells that express adeno-associated virus serotype 2-mediated BMP-7 gene enhanced odontoblastic differentiation

This present study investigated the potential of adeno-associated virus serotype 2 (AAV2) mediated BMP-7 (AAV2-BMP-7) to induce odontoblastic differentiation of human dental pulp cells (DPCs) in vitro. AAV2-BMP-7 was constructed to overexpress BMP-7, and the biologic effects of BMP-7 on DPCs were investigated by the evaluation of the activity of alkaline phosphatase (ALPase), the detection of the expression of dentin sialophosphoprotein (DSPP) and osteocalcin (OCN) expression and the analysis of the proliferative ability of the cells. DPCs that were infected with AAV2-BMP-7 displayed significantly upregulated ALP activity and formed mineralized nodules. Moreover, AAV2-BMP-7 promoted the expression of mineralization-related genes, which included DSPP and OCN. In addition, there was no significant difference between the proliferative ability of AAV2-BMP-7 and the control group. In conclusion, AAV2-BMP-7 promoted the odontoblastic differentiation in DPCs, a clear indication of the therapeutic potential of AAV2-BMP-7 in dental tissue regeneration.

Scaffold-based regeneration of skeletal tissues to meet clinical challenges

The management and reconstruction of damaged or diseased skeletal tissues have remained a significant global healthcare challenge. The limited efficacy of conventional treatment strategies for large bone, cartilage and osteochondral defects has inspired the development of scaffold-based tissue engineering solutions, with the aim of achieving complete biological and functional restoration of the affected tissue in the presence of a supporting matrix. Nevertheless, significant regulatory hurdles have rendered the clinical translation of novel scaffold designs to be an inefficient process, mainly due to the difficulties of arriving at a simple, reproducible and effective solution that does not rely on the incorporation of cells and/or bioactive molecules. In the context of the current clinical situation and recent research advances, this review will discuss scaffold-based strategies for the regeneration of skeletal tissues, with focus on the contribution of bioactive ceramic scaffolds and silk fibroin, and combinations thereof, towards the development of clinically viable solutions.