Early gene expression analyzed by cDNA microarray and RT-PCR in osteoblasts cultured with water-soluble and low molecular chitooligosaccharide

Chitosan derived chito-oligosaccharides promote osteoblast differentiation and offer anti-osteoporotic potential: Molecular and morphological evidence from a zebrafish model

This study delves into the potential of chito-oligosaccharides (COS) to promote osteoblast differentiation and prevent osteoporosis, utilizing experiments with mouse MSCs and the zebrafish model. The preliminary biocompatibility study affirms the non-toxic nature of COS across various concentrations. In the osteoblast differentiation study, COS enhances ALP activity and calcium deposition at the cellular level. Moreover, COS induces the upregulation of molecular markers, including Runx2, Type I collagen, ALP, osteocalcin, and osteonectin in mouse MSCs. Zebrafish studies further demonstrate COS's anti-osteoporotic effects, showcasing its ability to expedite fin fracture repair, vertebral mineralization, and bone mineralization in dexamethasone-induced osteoporosis models. The scale regenerative study reveals that COS mitigates the detrimental effects of dexamethasone induced osteoclastic activity, reducing TRAP and hydroxyproline levels while elevating the expression of Runx2a MASNA isoform, collagen2α, OC, and ON mRNAs. Additionally, COS enhances calcium and phosphorus levels in regenerated scales, impacting the bone-healthy calcium-to‑phosphorus ratio. The study also suggests that COS modulates the MMP3-Osteopontin-MAPK signaling pathway. Overall, this comprehensive investigation underscores the potential of COS to prevent and treat osteoporosis. Its multifaceted cellular and molecular effects, combined with in vivo bone regeneration and repair, propose that COS may be effective in addressing osteoporosis and related bone disorders. Nonetheless, further research is imperative to unravel underlying mechanisms and optimize clinical applications.

Chitosan degradation products promote healing of burn wounds of rat skin

Burns can impair the barrier function of the skin, and small burns can also cause high mortality. The WHO has described that over 180,000 people die of burns worldwide each year. Thus, the treatment of burn wounds is a major clinical challenge. Chitooligosaccharides (COS) are alkaline amino oligosaccharides with small molecular weights obtained by enzyme or chemical degradation of chitosan. With the characteristics of biocompatibility, water solubility and degradability, it has attracted increasing attention in the fields of biomedicine. In the present study, we used COS to treat deep second-degree burn wounds of rat skin and found that COS was able to promote wound healing. We also revealed that COS could promote fibroblast proliferation. Transcriptome sequencing analysis was performed on COS-treated fibroblasts to identify the underlying mechanisms. The results showed that COS was able to promote wound healing through regulation of the mitogen-activated protein kinase (MAPK) pathway and growth factor Hepatocyte Growth Factor (HGF). Our results provide a potential drug for burn wound therapy and the related molecular mechanism.

MALAT1 regulates osteogenic differentiation of human periodontal ligament stem cells through mediating miR-155-5p/ETS1 axis

BACKGROUND

Osteogenic differentiation of human periodontal ligament stem cells is essential to periodontal regeneration treatment for periodontitis. This study investigated the mechanism of lncRNAs-related osteogenic differentiation.

METHODS

Human periodontal ligament stem cells were extracted from human periodontal ligament and identified via flow cytometry. After being induced into osteogenic differentiation for three weeks using osteoblast inducing conditional media, human periodontal ligament stem cells were transfected with siRNA-MALAT1, or miR-155-5p inhibitor. Human periodontal ligament stem cells osteogenesis was observed by alkaline phosphatase staining, followed by alizarin red staining for evaluating mineralized nodes formation. Runt-related gene 2, collagen-1 and osteocalcin expressions were assessed by western blot and qRT-PCR.

RESULTS

MALAT1 expression was assumed a negative correlation with miR-155-5p expression which was dropping over time in differentiating human periodontal ligament stem cells. MALAT1 could bind with miR-155-5p, and E26 transformation specific-1 (ETS1) was the targeted gene of miR-155-5p. Silenced MALAT1 suppressed ALP activity and mineralized nodes formation and inhibited the expressions of runt-related gene 2, collagen-1 and osteocalcin in differentiating human periodontal ligament stem cells, while miR-155-5p inhibitor reversed the effect of si-MALAT1 on differentiation of human periodontal ligament stem cells.

CONCLUSION

MALAT1 modulated differentiation of human periodontal ligament stem cells via regulating miR-155-5p.

Austalide K from the Fungus Penicillium rudallense Prevents LPS-Induced Bone Loss in Mice by Inhibiting Osteoclast Differentiation and Promoting Osteoblast Differentiation

Osteoporosis is a chronic disease that has become a serious public health problem due to the associated reduction in quality of life and its increasing financial burden. It is known that inhibiting osteoclast differentiation and promoting osteoblast formation prevents osteoporosis. As there is no drug with this dual activity without clinical side effects, new alternatives are needed. Here, we demonstrate that austalide K, isolated from the marine fungus Penicillium rudallenes, has dual activities in bone remodeling. Austalide K inhibits the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation and improves bone morphogenetic protein (BMP)-2-mediated osteoblast differentiation in vitro without cytotoxicity. The nuclear factor of activated T cells c1 (NFATc1), tartrate-resistant acid phosphatase (TRAP), dendritic cell-specific transmembrane protein (DC-STAMP), and cathepsin K (CTSK) osteoclast-formation-related genes were reduced and alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), osteocalcin (OCN), and osteopontin (OPN) (osteoblast activation-related genes) were simultaneously upregulated by treatment with austalide K. Furthermore, austalide K showed good efficacy in an LPS-induced bone loss in vivo model. Bone volume, trabecular separation, trabecular thickness, and bone mineral density were recovered by austalide K. On the basis of these results, austalide K may lead to new drug treatments for bone diseases such as osteoporosis.

Chitosan applications in studying and managing osteosarcoma

Osteosarcoma has a high prevalence among children and adolescents. Common treatments of this disease are not promising enough. Molecular processes involved in the pathogenesis of osteosarcoma are not fully understood. Besides, the remnants of tumor cells after surgery can cause bone destruction and recurrence of the disease. Thus, there is a need to develop novel drugs or enhancing the currently-used drugs as well as identifying bone-repairing methods. Chitosan is a natural compound produced by the deacetylation of chitin. Research has shown that chitosan can be used in various fields due to its beneficial effects, such as biodegradability and biocompatibility. Regarding cancer, chitosan exerts several anti-tumor activities. Moreover, it can be used in diagnostic techniques, drug delivery systems, and cell culture methods. Herein, we aim to discuss the potential roles of chitosan in studying and treating osteosarcoma. We review the literature on chitosan's applications as a drug delivery system and how it can be combined with other substances to improve its ability of local drug delivery. We take a look into the studies concerning the possible benefits of chitosan in the field of bone tissue engineering and 3D culturing. Furthermore, anti-cancer activities of different compounds of chitosan are reviewed.

Biomimetic and osteogenic 3D silk fibroin composite scaffolds with nano MgO and mineralized hydroxyapatite for bone regeneration

Artificial bioactive materials have received increasing attention worldwide in clinical orthopedics to repair bone defects that are caused by trauma, infections or tumors, especially dedicated to the multifunctional composite effect of materials. In this study, a weakly alkaline, biomimetic and osteogenic, three-dimensional composite scaffold (3DS) with hydroxyapatite (HAp) and nano magnesium oxide (MgO) embedded in fiber (F) of silkworm cocoon and silk fibroin (SF) is evaluated comprehensively for its bone repair potential in vivo and in vitro experiments, particularly focusing on the combined effect between HAp and MgO. Magnesium ions (Mg²⁺) has long been proven to promote bone tissue regeneration, and HAp is provided with osteoconductive properties. Interestingly, the weak alkaline microenvironment from MgO may also be crucial to promote Sprague-Dawley (SD) rat bone mesenchymal stem cells (BMSCs) proliferation, osteogenic differentiation and alkaline phosphatase (ALP) activities. This SF/F/HAp/nano MgO (SFFHM) 3DS with superior biocompatibility and biodegradability has better mechanical properties, BMSCs proliferation ability, osteogenic activity and differentiation potential compared with the scaffolds adding HAp or MgO alone or neither. Similarly, corresponding meaningful results are also demonstrated in a model of distal lateral femoral defect in SD rat. Therefore, we provide a promising 3D composite scaffold for promoting bone regeneration applications in bone tissue engineering.

Heat shock protein 90 alpha and 14-3-3η in postmenopausal osteoporotic rats with varying levels of serum FSH

PURPOSE

This study compared the severity of osteoporosis and screened differentially expressed proteins in postmenopausal osteoporotic rats with varying levels of serum follicle stimulating hormone (FSH).

METHODS

Thirty-six Sprague Dawley female rats were divided into four groups: sham operation (sham) group, ovariectomy (OVX) group, FSH and ovariectomy (OVX + FSH) group, and Leuprorelin (LE) and ovariectomy group (OVX + LE). Body weight, serum estradiol, FSH, tartrate-resistant acid phosphatase, alkaline phosphatase, and bone mineral density were measured. We randomly selected six rats each from the OVX and OVX + FSH groups to detect differentially expressed proteins by data-independent acquisition, and we verified the results in the remaining six rats by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Nineteen proteins were upregulated and 36 proteins were downregulated in the OVX + FSH group. The expression of heat shock protein 90 alpha (Hsp90α) and 14-3-3η protein was significantly different between the OVX and OVX + FSH groups, and both were linearly correlated with bone trabecular area. Results were verified by ELISA and were found to be consistent with the results of data-independent acquisition.

DISCUSSION

In rats with high serum FSH, expression of Hsp90α protein was increased and expression of 14-3-3η protein was decreased. Both changes in protein expression were strongly correlated with bone trabecular area.

Sustained release of TGF-β3 from polysaccharide nanoparticles induces chondrogenic differentiation of human mesenchymal stromal cells

Medical treatment of certain diseases and biomedical implants are tending to use delivery systems on the nanoscale basis for biologically active factors including drugs (e. g. antibiotics) or growth factors. Nanoparticles are a useful tool to deliver bioactive substances of different chemical nature directly to the site where it is required in the patient. Here we developed three innovative delivery systems based on different polysaccharides in order to induce a sustained release of TGF-β₃ to mediate chondrogenesis of human mesenchymal stromal cells. We were able to encapsulate the protein into nanoparticles and subsequently release TGF-β₃ from these particles. The protein was still active and was able to induce chondrogenic differentiation of human mesenchymal stromal cells.

Sulfonated chitosan oligosaccharide alleviates the inhibitory effect of basic fibroblast growth factor on osteogenic differentiation of human periodontal ligament stem cells

BACKGROUND

Periodontal ligament stem cells (PDLSCs) play an essential role in periodontal tissue repair. Basic fibroblast growth factor (bFGF) has been used in the clinical treatment of periodontal disease. However, studies have shown that bFGF inhibits the osteogenic differentiation of PDLSCs, which is not conducive to alveolar bone repair. Sulfonated chitosan oligosaccharide (SCOS), a heparan-like compound, can maintain the conformation of bFGF and promote its proliferation activity. This study investigated the effects of bFGF in combination with SCOS on the osteogenic differentiation of hPDLSCs.

METHODS

hPDLSCs were isolated from healthy human periodontal ligament and identified by flow cytometry and immunofluorescence. The affinity between SCOS and bFGF was analyzed by surface plasmon resonance. Changes in osteogenic differentiation by combination of bFGF with SCOS were analyzed by alkaline phosphatase activity assay, Sirius Red staining, and Alizarin Red staining. Expression of genes and proteins was investigated by western blotting and reverse transcription-quantitative PCR.

RESULTS

Extracted hPDLSCs were mesenchymal stem cells with pluripotent differentiation potential. SCOS exhibited an affinity for bFGF. bFGF (20 ng/mL) promoted the proliferation of hPDLSCs, but inhibited their osteogenic differentiation. SCOS alleviated the inhibitory effect of bFGF on the osteogenic differentiation of hPDLSCs.

CONCLUSIONS

SCOS can reduce the inhibitory effect of bFGF on the osteogenic differentiation of hPDLSCs. This study provides evidence for the clinical use of bFGF to repair periodontal tissue.

Inhibition of the negative effect of high glucose on osteogenic differentiation of bone marrow stromal cells by silicon ions from calcium silicate bioceramics

Human bone marrow stem cells (hBMSCs) are exploited for miscellaneous applications in bone tissue engineering where they are mainly used as seed cells. However, high glucose (HG) environment has negative impacts on the proliferation and osteogenic differentiation of hBMSCs, thus reducing the bone formation in diabetic patients. In our former research works, we discovered that silicon (Si) ions extracted from silicate-based bioceramics are able to stimulate the proliferation and osteogenic differentiation of hBMSCs under normal culture condition. This study aimed to investigate if Si ions could prevent HG-induced inhibition of proliferation and osteogenesis of hBMSCs. We found that 2.59 ppm concentration of Si ions promoted the proliferation of hBMSCs under HG condition. The results from alkaline phosphatase (ALP) activity assay, Alizarin red S staining and quantitative real-time PCR analysis of osteogenic genes (BMP2, RUNX2, ALP, COL1 and OCN) demonstrated that the 15.92 ppm concentration of Si ions prevented HG-induced inhibition of the osteogenic differentiation of hBMSCs. Moreover, application of Si ions reduced the level of reactive oxygen species in HG-treated hBMSCs. In HG-treated hBMSCs following 15.92 ppm Si ions treatment, activation of BMP2/SMAD signaling pathway was detected, as indicated by the increased expression of BMP2 receptors and its downstream genes such as SMAD1, SMAD4 and SMAD5. Taken together, we provide evidence that the specific concentration of Si ions compensated HG-induced inhibition of proliferation and osteogenic differentiation of hBMSCs through antioxidant effect and modulation of BMP2/SMAD pathway. The results suggest that silicate-based bioceramics might be good scaffold biomaterials for bone engineering applications in diabetes patients.

Chitooligosaccharide inhibits RANKL-induced osteoclastogenesis and ligation-induced periodontitis by suppressing MAPK/ c-fos/NFATC1 signaling

Considering the high rate of osteoclast-related diseases worldwide, research targeting osteoclast formation/function is crucial. In vitro, we demonstrated that chitooligosaccharide (CS) dramatically inhibited osteoclastogenesis as well as osteoclast function dose-dependently. CS suppressed osteoclast-specific genes expression during osteoclastogenesis. Furthermore, we found that CS attenuated receptor activator of nuclear factor kappa B ligand (RANKL)-mediated mitogen-activated protein kinase (MAPK) pathway involving p38, erk1/2, and jnk, leading to the reduced expression of c-fos and nuclear factor of activated T cells c1 (NFATc1) during osteoclast differentiation. In vivo, we found CS protected rats from periodontitis-induced alveolar bone loss by micro-computerized tomography and histological analysis. Overall, CS inhibited RANKL-induced osteoclastogenesis and ligature-induced rat periodontitis model, probably by suppressing the MAPK/c-fos/NFATc1 signaling pathway. Therefore, CS may be a safe and promising treatment for osteoclast-related diseases.

Enhanced osteogenesis and angiogenesis by PCL/chitosan/Sr-doped calcium phosphate electrospun nanocomposite membrane for guided bone regeneration

Membranes play pivotal role in guided bone regeneration (GBR) technique for reconstruction alveolar bone. GBR membrane that is able to stimulate both osteogenic and angiogenic differentiation of cells may be more effective in clinic practice. Herein, we fabricated the Sr-doped calcium phosphate/polycaprolactone/chitosan (Sr-CaP/PCL/CS) nanohybrid fibrous membrane by incorporating 20 wt% bioactive Sr-CaP nanoparticles into PCL/CS matrix via one-step electrospinning method, in order to endow the membrane with stimulation of osteogenesis and angiogenesis. The physicochemical properties, mechanical properties, Sr²⁺ release behavior, and the membrane stimulate bone mesenchymal stem cell (BMSCs) differentiation were evaluated in comparison with PCL/CS and CaP/PCL/CS membranes. The SEM images revealed that the nanocomposite membrane mimicked the extracellular matrix structure. The release curve presented a 28-day long continuous release of Sr²⁺ and concentration which was certified in an optimal range for positive biological effects at each timepoint. The in vitro cell culture experiments certified that the Sr-CaP/PCL/CS membrane enjoyed excellent biocompatibility and remarkably promoted rat bone mesenchymal stem cell (BMSCs) adhesion and proliferation. In terms of osteogenic differentiation, BMSCs seeded on the Sr-CaP/PCL/CS membrane showed a higher ALP activity level and a better matrix mineralization. What's more, the synergism of the Sr²⁺ and CaP from the Sr-CaP/PCL/CS membrane enhanced BMSCs angiogenic differentiation, herein resulting in the largest VEGF secretion amount. Consequently, the Sr-CaP/PCL/CS nanohybrid electrospun membrane has promising applications in GBR.

Crosstalk between chitosan and cell signaling pathways

The field of tissue engineering (TE) experiences its most exciting time in the current decade. Recent progresses in TE have made it able to translate into clinical applications. To regenerate damaged tissues, TE uses biomaterial scaffolds to prepare a suitable backbone for tissue regeneration. It is well proven that the cell-biomaterial crosstalk impacts tremendously on cell biological activities such as differentiation, proliferation, migration, and others. Clarification of exact biological effects and mechanisms of a certain material on various cell types promises to have a profound impact on clinical applications of TE. Chitosan (CS) is one of the most commonly used biomaterials with many promising characteristics such as biocompatibility, antibacterial activity, biodegradability, and others. In this review, we discuss crosstalk between CS and various cell types to provide a roadmap for more effective applications of this polymer for future uses in tissue engineering and regenerative medicine.

Layer-by-layer deposition of chitosan nanoparticles as drug-release coatings for PCL nanofibers

Modified PCL fiber mat with fluorescently labeled CS-TPP nanoparticle system via LbL dip coating.

Bone tissue engineering strategy based on the synergistic effects of silicon and strontium ions

Multipotent human bone marrow mesenchymal stem cells (hBMSCs) are commonly used as seed cells in bone tissue engineering, but their clinical application is limited due to two challenges. One is the expansion of hBMSCs without loss of the stemness, and the other is the stimulation of osteogenic differentiation of hBMSCs when combined with biomaterials. In this study we demonstrated an approach by firstly elucidating the functional effects and optimal concentrations of Si and Sr ions on the proliferation and osteogenic differentiation of hBMSCs, and then designing bioactive bioceramic/alginate hydrogels which could release Si and Sr bioactive ions in the same optimal concentrations range for activation of the cells in vivo. The results showed that Si and Sr ions could synergistically stimulate cell proliferation without losing the stemness. Furthermore, at higher concentrations, Si and Sr ions stimulated osteogenic differentiation instead of enhancing proliferation. The designed bioactive hydrogels revealed activity to stimulate not only the osteogenic differentiation of encapsulated hBMSCs, but also the blood vessel formation in vivo. These results suggested that the design of biomaterials based on the biological function of different material elements was an effective approach for bone tissue engineering applications.

STATEMENT OF SIGNIFICANCE

The clinical application of multipotent human bone marrow mesenchymal stem cells (hBMSCs) in bone tissue engineering is limited due to two challenges. One is the expansion of cells without loss of the stemness, and the other is the stimulation of osteogenic differentiation of hBMSCs within the biomaterial scaffolds. Herein, we demonstrated an approach by firstly elucidating the functional effects and optimal concentrations of Si and Sr ions on the proliferation without losing stemness and osteogenic differentiation of hBMSCs, and then designing a bioactive bioceramic/alginate hydrogel which could release Si and Sr ions for in vivo activation of cells. The bioactive hydrogels revealed activity to stimulate not only osteogenic differentiation of encapsulated hBMSCs, but also the blood vessel formation in vivo. Our work provided an effective approach to design effective biomaterials for tissue engineering.

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.

Polygonatum sibiricum polysaccharide inhibits osteoporosis by promoting osteoblast formation and blocking osteoclastogenesis through Wnt/β-catenin signalling pathway

Bone homeostasis is maintained by a balance between bone formation by osteoblasts and bone resorption by osteoclasts. Osteoporosis occurs when osteoclast activity surpasses osteoblast activity. Our previous studies showed the plant-derived natural polysaccharide (Polygonatum sibiricum polysaccharide or PSP) had significant anti-ovariectomy (OVX)-induced osteoporosis effects in vivo, but the mechanisms of PSP’s anti-osteoporosis effect remains unclear. In this study, we assessed PSP’s effect on the generation of osteoblast and osteoclast in vitro. This study showed that PSP promoted the osteogenic differentiation of mouse bone marrow stromal cells (BMSCs) without affecting BMPs signaling pathway. This effect was due to the increased nuclear accumulation of β-catenin, resulting in a higher expression of osteoblast-related genes. Furthermore, the study showed PSP could inhibit the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis and exert prophylatic protection against LPS-induced osteolysis in vivo. This effect was also related to the increased nuclear accumulation of β-catenin, resulting in the decreased expression of osteoclast-related genes. In conclusion, our results showed that PSP effectively promoted the osteogenic differentiation of mouse BMSCs and suppressed osteoclastogenesis; therefore, it could be used to treat osteoporosis.

Biodegradable chitosan nanoparticle coatings on titanium for the delivery of BMP-2

A simple method for the functionalization of a common implant material (Ti6Al4V) with biodegradable, drug loaded chitosan-tripolyphosphate (CS-TPP) nanoparticles is developed in order to enhance the osseointegration of endoprostheses after revision operations. The chitosan used has a tailored degree of acetylation which allows for a fast biodegradation by lysozyme. The degradability of chitosan is proven via viscometry. Characteristics and degradation of nanoparticles formed with TPP are analyzed using dynamic light scattering. The particle degradation via lysozyme displays a decrease in particle diameter of 40% after 4 days. Drug loading and release is investigated for the nanoparticles with bone morphogenetic protein 2 (BMP-2), using ELISA and the BRE luciferase test for quantification and bioactivity evaluation. Furthermore, nanoparticle coatings on titanium substrates are created via spray-coating and analyzed by ellipsometry, scanning electron microscopy and X-ray photoelectron spectroscopy. Drug loaded nanoparticle coatings with biologically active BMP-2 are obtained in vitro within this work. Additionally, an in vivo study in mice indicates the dose dependent induction of ectopic bone growth through CS-TPP-BMP-2 nanoparticles. These results show that biodegradable CS-TPP coatings can be utilized to present biologically active BMP-2 on common implant materials like Ti6Al4V.

Chitosan Degradation Products Promote Nerve Regeneration by Stimulating Schwann Cell Proliferation via miR-27a/FOXO1 Axis

Natural polysaccharides are biomaterials widely used for constructing scaffolds in tissue engineering. While natural polysaccharides have been shown to robustly promote tissue regeneration, the underlying molecular mechanism remains largely unknown. Here, we show that chitooligosaccharides (COS), the intermediate products of chitosan degradation, stimulate peripheral nerve regeneration in rats. Our experiment also shows that COS stimulate the proliferation of Schwann cells (SCs) during nerve regeneration. By analyzing the transcriptome and gene regulatory network, we identified the miR-27a/FOXO1 axis as the main signaling pathway for mediating the proliferative effects of COS on SCs. COS increase the expression level of miR-27a and cause a reduction of FOXO1, which subsequently accelerates the cell cycle and stimulates SC proliferation to stimulate nerve regeneration. These findings define a basic pathway for oligosaccharides-mediated cell proliferation and reveal a novel aspect of polysaccharide biomaterials in tissue engineering.

Potency of fish collagen as a scaffold for regenerative medicine

Cells, growth factors, and scaffold are the crucial factors for tissue engineering. Recently, scaffolds consisting of natural polymers, such as collagen and gelatin, bioabsorbable synthetic polymers, such as polylactic acid and polyglycolic acid, and inorganic materials, such as hydroxyapatite, as well as composite materials have been rapidly developed. In particular, collagen is the most promising material for tissue engineering due to its biocompatibility and biodegradability. Collagen contains specific cell adhesion domains, including the arginine-glycine-aspartic acid (RGD) motif. After the integrin receptor on the cell surface binds to the RGD motif on the collagen molecule, cell adhesion is actively induced. This interaction contributes to the promotion of cell growth and differentiation and the regulation of various cell functions. However, it is difficult to use a pure collagen scaffold as a tissue engineering material due to its low mechanical strength. In order to make up for this disadvantage, collagen scaffolds are often modified using a cross-linker, such as gamma irradiation and carbodiimide. Taking into account the possibility of zoonosis, a variety of recent reports have been documented using fish collagen scaffolds. We herein review the potency of fish collagen scaffolds as well as associated problems to be addressed for use in regenerative medicine.

Maxillary sinus floor elevation with a tissue-engineered bone composite of deciduous tooth stem cells and calcium phosphate cement in goats

The study aimed to assess the effect of maxillary sinus floor elevation with tissue-engineered bone constructed from deciduous tooth stem cells (DTSCs) and calcium phosphate cement (CPC). The stem cells from goat deciduous teeth (SGDs) were isolated and transfected by means of the adenovirus with an enhanced green fluorescent protein gene (AdEGFP). As many as 18 bilateral maxillary sinuses of nine goats were randomly allocated into three groups (n = 6/group): group A (SGDs-CPC compound), group B (CPC alone) and group C (autogenous bone obtained from an iliac crest). All the samples were evaluated by computed tomography (CT), histology and histomorphometric analysis. Furthermore, the fate of implanted SGDs was traced using an immunohistochemical staining method in the decalcified samples. SGDs might be differentiated into osteoblasts in an osteogenic medium. In the present study, three-dimensional CT analysis showed that the volume of newly formed bone in group A was greater than that in the other two groups. After a healing period of 3 months, sequential analyses of triad-colour fluorescence labelling, histology and histomorphology indicated that the SGDs-CPC compound primarily promoted bone formation and mineralization at 2 and 3 months after the operation. Moreover, the areas of new bone formation in elevated sinuses were 41.82 ± 6.24% in the SGDs-CPC group, which was significantly higher than the 30.11 ± 8.05% in the CPC-alone group or the 23.07 ± 10.21% in the autogenous bone group. Immunohistochemical staining revealed that GFP and OCN were both expressed in the new bone tissue for the samples with eGFP, which suggested that the implanted SGDs might have contributed to new bone formation on the elevated sinus floor. SGDs can promote new bone formation and maturation in the goat maxillary sinus, and the tissue-engineered bone composite of SGDs and CPC might be a potential substitute for existing maxillary sinus floor elevation methods. Copyright © 2014 John Wiley & Sons, Ltd.

Chitosan rate of uptake in HEK293 cells is influenced by soluble versus microparticle state and enhanced by serum-induced cell metabolism and lactate-based media acidification

Chitosan is a biocompatible polysaccharide composed of glucosamine and N-acetylglucosamine. The polymer has a unique behavior of fluctuating between soluble chains at pH 6 and insoluble microparticles at pH 7. The purpose of this study was to test the hypothesis that chitosan structure, solubility state, and serum influence the rate of cell uptake. Chitosans with 80% and 95% degree of deacetylation (medium and low viscosity) were tagged with rhodamine and analyzed for particle size, media solubility, and uptake by HEK293 epithelial cells using live confocal microscopy and flow cytometry. In media pH 7.4 with or without 10% serum, chitosans fully precipitated into 0.5 to 1.4 µm diameter microparticles with a slight negative charge. During 24 h of culture in serum-free medium, chitosan particles remained extracellular. In cultures with serum, particles were taken up into intracellular vesicles in a serum dose-dependent manner. Opsonization of chitosan with serum, or replacement of serum by epidermal growth factor (EGF) failed to mediate serum-free chitosan particle uptake. Serum stimulated cells to acidify the media, partly by lactate generation. Media acidified to pH 6.5 by 7 mM lactate maintained 50% of chitosan in the soluble fraction, and led to minor uniform serum-free uptake in small vesicles.

CONCLUSION

Media acidification mediates minor in vitro uptake of non-biofouled soluble chitosan chains, while serum-biofouled insoluble chitosan microparticles require sustained serum exposure to generate energy required for macropinocytosis.

Glucosamine promotes osteogenic differentiation of dental pulp stem cells through modulating the level of the transforming growth factor-beta type I receptor

Dental pulp stem cells (DPSCs) are clonogenic, self-renewing, and multi-potential DPSCs capable of differentiating into osteoblasts. In this study, primary cell cultures were obtained from human dental pulp tissue of developing third molars, and flow cytometry was used to sort the subpopulation of DPSCs with STRO-1 and CD146 double-positive expression (denoted "DPSCs"). It was noted that DPSCs exhibited superior clonogenic potential and osteogenic differentiation capability than the dental pulp cell subpopulation with STRO-1 and CD146 double-negative expression (denoted DPCs). Furthermore, a low concentration (0.005 mg/ml) of exogenous glucosamine (GlcN) was effective in promoting the early osteogenic differentiation of DPSCs through the transforming growth factor-beta receptor (TGF-betar) type I and Smads signal pathways, which upregulated the Runt-related transcription factor 2/core-binding factor alpha1 (Runx2/Cbfa1) and alkaline phosphatase at both the mRNA and protein levels. In the presence of osteogenic supplements, GlcN-treated DPSCs produced more mineralized-matrix deposition than did the untreated groups. Taken together, this study demonstrates the capacity of GlcN to promote the osteogenic differentiation of human DPSCs, and the underlying mechanism involves a TGF-betar-dependent Smad signal pathway.

Effects of chitosan-coated pressed calcium sulfate pellets combined with recombinant human bone morphogenetic protein 2 on bone formation in femoral condyle-contained bone defects

Calcium sulfate has a rapid degradation rate and little osteoinductive capability. Chitosan-coated pressed calcium sulfate pellets combined with recombinant human bone morphogenetic protein 2 (rhBMP-2) have been developed that exhibit decreased resorption speed and increased compressive strength and osteoinduction. A rabbit femoral condyle-contained bone defect model was used to study the restoration of the defects treated with chitosan-coated pressed calcium sulfate pellets combined with rhBMP-2, chitosan-coated pressed calcium sulfate pellets, and uncoated pressed calcium sulfate pellets. No pellets were implanted in the control group. After 3 and 13 weeks, the results indicated that chitosan-coated pressed calcium sulfate pellets exhibited relatively slower resorption that closely coincides with the growth rate of new bone and enhanced osteogenesis when combined with rhBMP-2.

Reconstruction of goat tibial defects using an injectable tricalcium phosphate/chitosan in combination with autologous platelet-rich plasma

Injectable scaffolds held great promise for the reconstruction of bone defects. We prepared an injectable composite named PTC by combining TCP/chitosan (TC) with platelet-rich plasma (PRP). The objective of this study was to investigate the composite's mechanical and biological properties. First, we found that the introduction of PRP in TC showed no adverse effect on mechanical strength and that there were no significant differences in compressive strength between PTC and TC (P>0.05). In cell culture experiments, both cell count and alkaline phosphatase (ALP) activity measurements of PTC were higher than those of TC. The high levels of Cbfa1 and TGF-beta were detected early in PTC-induced MSCs by reverse transcriptase polymerase chain reaction. Bone formation following expression of collagen type I, osteocalcin, osteonectin and calcium nodules was also observed in PRP-induced MSCs. Finally, this composite was injected into the tibial bone defect in a goat model, and its ability to induce bone regeneration was observed. Sixteen weeks after the implantation of this composite, the tibial defects had completely recuperated, with significantly better formation of mature bone and less residual material than in the control. These results demonstrate that our composite, with its concomitant mechanical strength, biocompatibility, and osteoinductive properties, has significant potential as an injectable material for the treatment of bone defects.

Hard tissue formation of STRO-1-selected rat dental pulp stem cells in vivo

The objective of this study was to examine hard tissue formation of STRO-1-selected rat dental pulp-derived stem cells, seeded into a calcium phosphate ceramic scaffold, and implanted subcutaneously in mice. Previously, STRO-1 selection was used to obtain a mesenchymal stem cell progenitor subpopulation from primary dental pulp-derived stem cells. In the current study, these cells were cultured with three different media: "BMP-plus" medium containing dexamethasone and 100 ng/mL of rhBMP-2, "odontogenic" medium containing dexamethasone, and "control" medium without supplements. The cell-scaffold complexes were cultured in these media for 1, 4, or 8 days before implantation. Histological analysis demonstrated that the cultures with BMP-plus and 4 days of culture gave the highest percentage of hard tissue formation per implant (36 +/- 9% of pore area). Real-time PCR confirmed these results. In conclusion, STRO-1-selected dental pulp stem cells show effective hard tissue formation in vivo, and a short in vitro culture period and addition of BMP-2 can enhance this effect.

Improvement of porous beta-TCP scaffolds with rhBMP-2 chitosan carrier film for bone tissue application

Ceramic materials are osteoconductive matrices extensively used in bone tissue engineering approaches. The performance of these types of biomaterials can be greatly enhanced by the incorporation of bioactive agents and materials. It is previously reported that chitosan is a biocompatible, biodegradable material that enhances bone formation. In the other hand, bone morphogenetic protein-2 (BMP-2) is a well-known osteoinductive factor. In this work we coated porous beta-tricalcium phosphate (beta-TCP) scaffolds with recombinant human BMP-2 (rhBMP-2) carrier chitosan films and studied how they could modify the ceramic physicochemical properties, cellular response, and in vivo bone generation. Initial beta-TCP disks with an average diameter of 5.78 mm, 2.9 mm thickness, and 53% porosity were coated with a chitosan film. These coating properties were studied by X-ray diffraction, Fourier transform-infrared analysis, transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray analysis (EDX). Treatment modified the scaffold porous distribution and increased the average hardness. The biocompatibility did not seem to be altered. In addition, adhered C2C12 cells expressed alkaline phosphatase activity, related to cell differentiation toward osteogenic lineage, due to the incorporation of rhBMP-2. On the other hand, in vivo observations showed new bone formation 3 weeks after surgery, a much shorter time than control beta-TCP ceramics. These results suggest that developed coating improved porous beta-TCP scaffold for bone tissue applications and added osteoinductive properties.

Proliferation and differentiation of MC3T3-E1 cells on calcium phosphate/chitosan coatings

The incorporation of chitosan into electro-deposited calcium phosphate (CaP) coatings increases bone marrow stromal cell attachment. We hypothesized that such electrodeposited CaP/chitosan coatings can also enhance the proliferative ability and differentiation potential of osteoblasts. To verify this hypothesis, we cultured osteoblast-like MC3T3-E1 cells on these CaP coatings. It was found that MC3T3-E1 cells cultured on the electrodeposited CaP/chitosan coatings had cell proliferation rates higher than those on the electrodeposited CaP coatings. At the same time, both alkaline phosphatase activity and collagen expression were increased, and both bone sialoprotein and osteocalcin genes were up-regulated when MC3T3-E1 cells were cultured on the electrodeposited CaP/chitosan coatings. Additionally, within the range of selected chitosan concentrations in solution, no significant difference was found between the CaP/chitosan coatings. Our results suggest that the electrodeposited CaP/chitosan coatings are favorable to the proliferation and differentiation of MC3T3-E1 cells, which may endow them with great potential for future applications.

Hard tissue formation in a porous HA/TCP ceramic scaffold loaded with stromal cells derived from dental pulp and bone marrow

The aim of this study was to compare the ability of hard tissue regeneration of four types of stem cells or precursors under both in vitro and in vivo situations. Primary cultures of rat bone marrow, rat dental pulp, human bone marrow, and human dental pulp cells were seeded onto a porous ceramic scaffold material, and then either cultured in an osteogenic medium or subcutaneously implanted into nude mice. For cell culture, samples were collected at weeks 0, 1, 3, and 5. Results were analyzed by measuring cell proliferation rate and alkaline phosphatase activity, scanning electron microscopy, and real-time PCR. Samples from the implantation study were retrieved after 5 and 10 weeks and evaluated by histology and real-time PCR. The results indicated that in vitro abundant cell growth and mineralization of extracellular matrix was observed for all types of cells. However, in vivo matured bone formation was found only in the samples seeded with rat bone marrow stromal cells. Real-time PCR suggested that the expression of Runx2 and the expression osteocalcin were important for the differentiation of bone marrow stromal cells, while dentin sialophosphoprotein contributed to the odontogenic differentiation. In conclusion, the limited hard tissue regeneration ability of dental pulp stromal cells questions their practical application for complete tooth regeneration. Repeated cell passaging may explain the reduction of the osteogenic ability of both bone- and dentinal-derived stem cells. Therefore, it is essential to develop new cell culture methods to harvest the desired cell numbers while not obliterating the osteogenic potential.

Chitosan monomer accelerates alkaline phosphatase activity on human osteoblastic cells under hypofunctional conditions

Chitosan is a natural polyaminosaccharide that is extensively applied as an antitumor and antirheumatic drug. However, there are few reports about its effects on hypofunctional osteoblasts in vitro. We investigated the biological characteristics of a human osteoblastic cell line (NOS-1 cells) that was cultured with a chitosan monomer-containing medium under simulated microgravity conditions. After 7 days of cell incubation under the conventional conditions, the flasks were transferred to a microgravity simulator for 3 days. In the 0.005% chitosan monomer supplemented group, the marker enzyme of biological mineralization, the alkaline phosphatase (ALP) activity, was significantly higher compared with the control group (p<0.05). A cDNA microarray was performed to investigate the effects on the mRNA level by chitosan monomer, and the fluorescent signal was analyzed. The interferon gamma (IFN-gamma) receptor gene was detected with a signal ration of 2.2. The slight increase of IFN-gamma receptor expression was confirmed after 3 days of incubation according to RT-PCR analysis. Western blot analysis also showed the increased expression of IFN-gamma receptor. These results suggest that a supra-low concentration of chitosan monomer may increase the ALP activity of osteoblastic cells through the IFN-gamma receptor at the early phase of cell culture and recover the activity for biological mineralization under the hypofunctional condition.

Early gene expression analyzed by cDNA microarray and real-time PCR in osteoblasts cultured with chitosan monomer

Chitosan has a variety of biological activities. Although it has been reported that chitosan promotes osteogenesis in bone lesions, little is known about how it modulates the hard tissue forming cells at the gene level. This study focused on gene expressions in osteoblasts cultured with a super-low concentration of chitosan monomer. cDNA probes were synthesized from isolated RNA and labeled with fluorescent dye. They were hybridized with Human 3.8 II cDNA microarray, and the fluorescent signal was analyzed. cDNA microarray analysis revealed that 10 genes concerning to various signaling-related molecules were expressed at > or =2.0-fold higher signal ratio levels in the experimental group when compared with the control group after 3 days. Real-time PCR analysis showed that chitosan monomer induced an increase in the expression of four signal transduction genes, mitogen-activated protein kinase (MAPK)K3, MAPKKK11, Rac1 and Shc1, together with the alkaline phosphatase gene. These results suggest that a super-low concentration of chitosan monomer could modulate the activity of osteoblastic cells through mRNA levels and that chitosan monomer directly affects signal transduction inside cells.

The integration of chitosan-coated titanium in bone: an in vivo study in rabbits

PROCEDURE

Much research is directed at surface modifications to enhance osseointegration of implants. A new potential coating is the biopolymer, chitosan, the deacetylated derivative of the natural polysaccharide, chitin. Chitosan is biocompatible, degradable, nontoxic, and exhibits osteogenic properties. The aim of this research was to investigate the hypothesis that chitosan-coated titanium supports bone formation and osseointegration.

MATERIALS AND METHODS

Chitosan (1 wt% of 92.3% deacetylated chitosan in 1% acetic acid) was solution cast and bonded to rough ground titanium pins (2-mm diameterx4-mm long) via silane reactions. Calcium phosphate sputter-coated titanium and uncoated titanium pins were used as controls. Two chitosan-coated pins, and 1 each of calcium phosphate coated and uncoated pins were implanted unilaterally in the tibia of 16 adult male New Zealand white rabbits. At 2, 4, 8, and 12 weeks, undecalcified sections were histologically evaluated for healing and bone formation.

RESULTS

Histological evaluations of tissues in contact with the chitosan-coated pins indicated minimal inflammatory response and a typical healing sequence of fibrous, woven bone formation, followed by development of lamellar bone. These observations were similar to those for tissues interfacing the control calcium phosphate-coated and uncoated titanium implants. Quantitative comparisons of the bone-implant interface were not possible since 31% of the implants migrated into the tibial marrow space after implantation due to insufficient cortical bone thickness to hold pins in place during healing.

CONCLUSION

These data support the hypothesis that chitosan-coatings are able to develop a close bony apposition or the osseointegration of dental/craniofacial and orthopedic implants.