The Effect of Bone Morphogenetic Protein 2 (BMP-2)/Estrogen Composite Nanoparticles on the Differentiation Function of Osteoporotic Bone Marrow Mesenchymal Stem Cells (BMSCs)

The menopausal hormone abnormal changes such as estrogen deficiency and increased FSH secretion in female patients in old age may cause osteoporosis which is plagued by patients. The pathogenesis of osteoporosis is not yet fully understood. BMP in the transforming growth factor-β superfamily is a key member in the process of bone growth and development, among which BMP-2 exerts critical roles. Impaired osteogenic differentiation of bone marrow mesenchymal stem cells (BMSC) contributes to the progress of osteoporosis. BMSC plays an indispensable role in treating osteoporosis and can develop into different directions through induction. As the regenerative medicine nanotechnology has become a new medical method, it is believed that BMSC can be used to treat osteoporosis and other related diseases. Our study analyzed the effects of BMP-2/estrogen composite nanoparticles on the proliferation and differentiation of osteoporotic BMSC cells to provide a reliable reference for the future treatment. Our results showed that BMP-2/estrogen composite nanoparticles promoted BMSC cell proliferation, increased ALP activity, decreased apoptosis rate, increased the expression of Col-1, Runx2 and Osterix, upregulated the osteogenic marker BMP-2. As confirmed by Alizarin Red staining, it could differentiate into osteoblasts and the content of Trap was decreased. In conclusion, our study confirms that BMP-2/estrogen composite nanoparticles can promote BMSC cell proliferation, osteogenic differentiation, and inhibit osteoclast differentiation, thereby providing new treatments and theoretical reference basis for treating osteoporosis.

Surface Modification of Polycaprolactone Scaffold With Improved Biocompatibility and Controlled Growth Factor Release for Enhanced Stem Cell Differentiation

Polycaprolactone (PCL) has been widely used as a scaffold material for tissue engineering. Reliable applications of the PCL scaffolds require overcoming their native hydrophobicity and obtaining the sustained release of signaling factors to modulate cell growth and differentiation. Here, we report a surface modification strategy for electrospun PCL nanofibers using an azide-terminated amphiphilic graft polymer. With multiple alkylation and pegylation on the side chains of poly-L-lysine, stable coating of the graft polymer on the PCL nanofibers was achieved in one step. Using the azide-alkyne “click chemistry”, we functionalized the azide-pegylated PCL nanofibers with dibenzocyclooctyne-modified nanocapsules containing growth factor, which rendered the nanofiber scaffold with satisfied cell adhesion and growth property. Moreover, by specific immobilization of pH-responsive nanocapsules containing bone morphogenetic protein 2 (BMP-2), controlled release of active BMP-2 from the PCL nanofibers was achieved within 21 days. When bone mesenchyme stem cells were cultured on this nanofiber scaffold, enhanced ossification was observed in correlation with the time-dependent release of BMP-2. The established surface modification can be extended as a generic approach to hydrophobic nanomaterials for longtime sustainable release of multiplex signaling proteins for tissue engineering.

Enhanced osseointegration of dental implants with reduced graphene oxide coating

Background: The implants of pure titanium (Ti) and its alloys can lead to implant failure because of their poor interaction with bone-associated cells during bone regeneration. Surface modification over implants has achieved successful implants for enhanced osseointegration.Methods: Herein, we prepared sandblasted, large-grit, and acid-etched (SLA) Ti (ST) implants with different surface modifications [i.e., reduced graphene oxide (rGO) and recombinant human bone morphogenetic protein-2 (rhBMP-2)] and investigated their dental tissue regenerating ability in animal models. We performed comparative studies in surface property, in vitro cellular behaviors, and in vivo osseointegration activity among different groups, including ST (control), rhBMP-2-immobilized ST (BI-ST), rhBMP-2-treated ST (BT-ST), and rGO-coated ST (R-ST).Results: Spectroscopic, diffractometric, and microscopic analyses confirmed that rGO was coated well around the surfaces of Ti discs (for cell study) and implant fixtures (for animal study). Furthermore, in vitro and in vivo studies revealed that the R-ST group showed significantly better effects in cell attachment and proliferation, alkaline phosphatase activity, matrix mineralization, and osseointegration than the control (ST), BI-ST, and BT-ST groups.Conclusion: Hence, we suggest that the rGO-coated Ti can be a promising candidate for the application to dental or even orthopedic implants due to its ability to accelerate the healing rate with the high potential of osseointegration.

Effects of Sparganii Rhizoma on Osteoclast Formation and Osteoblast Differentiation and on an OVX-Induced Bone Loss Model

Postmenopausal osteoporosis is caused by an imbalance between osteoclasts and osteoblasts and causes severe bone loss. Osteoporotic medicines are classified into bone resorption inhibitors and bone formation promoters according to the mechanism of action. Long-term use of bisphosphonate and selective estrogen receptor modulators (SERMs) can cause severe side effects in postmenopausal osteoporosis patients. Therefore, it is important to find alternative natural products that reduce osteoclast activity and increase osteoblast formation. Sparganii Rhizoma (SR) is the dried tuberous rhizome of Sparganium stoloniferum Buchanan-Hamilton and is called “samreung” in Korea. However, to date, the effect of SR on osteoclast differentiation and the ovariectomized (OVX)-induced bone loss model has not been reported. In vitro, tartrate-resistant acid phosphatase (TRAP) staining, western blots, RT-PCR and other methods were used to examine the effect of SR on osteoclast differentiation and osteoblasts. In vivo, we confirmed the effect of SR in a model of OVX-induced postmenopausal osteoporosis. SR inhibited osteoclast differentiation and decreased the expression of TNF receptor-associated factor 6 (TRAF6), nuclear factor of activated T cells 1 (NFATc1) and c-Fos pathway. In addition, SR stimulates osteoblast differentiation and increased protein expression of the bone morphogenetic protein 2 (BMP-2)/SMAD signaling pathway. Moreover, SR protected against bone loss in OVX-induced rats. Our results appear to advance our knowledge of SR and successfully demonstrate its potential role as a osteoclastogenesis-inhibiting and osteogenesis-promoting herbal medicine for the treatment of postmenopausal osteoporosis.

Secretion of BMP-2 by tumor-associated macrophages (TAM) promotes microcalcifications in breast cancer

Introduction Breast microcalcifications is a characteristic feature in diagnostic imaging and a prognostic factor of breast cancer. However, the underlying mechanisms of breast microcalcifications formation are not fully understood. Previous studies have shown that upregulation of bone morphogenetic protein 2 (BMP-2) is associated with the occurrence of microcalcifications and tumor-associated macrophages (TAMs) in the tumor microenvironment can secrete BMP-2. The aim of this study is to elucidate the role of secretion of BMP-2 by TAMs in promoting microcalcifications of breast cancer through immunohistochemical staining and co-culturing of breast cancer cells with TAMs. Methods A total of 272 patients diagnosed with primary invasive breast cancer from January 2010 to January 2012 in the First Hospital of China Medical University were included in this study. Immunohistochemical staining of CD68 (marker of entire macrophages), CD168 (marker of the M2-like macrophages) and BMP-2 were performed on 4-μm tissue microarray (TMA) sections. Following induction, THP-1 cells were differentiated to M2-like TAMs and were then co-cultured with breast cancer cells (MCF-7). Calcifications and BMP-2 expression were analyzed by Alizarin Red S staining and western blot, respectively. Results Immunohistochemical analysis showed that the expression of CD168 was significantly increased in tissues with microcalcifications and was correlated with the expression of BMP-2 and poor prognosis. The formation of cellular microcalcifications and BMP-2 expression were significantly increased in MCF-7 cells co-cultured with TAMs compared with MCF-7 cells alone. Conclusions These findings support the hypothesis that TAMs secrete BMP-2 to induce microcalcifications in breast cancer cells and influence prognosis via multiple pathways including BMP-2 and its downstream factors.

Construction of developmentally inspired periosteum-like tissue for bone regeneration

The periosteum, a highly vascularized thin tissue, has excellent osteogenic and bone regenerative abilities. The generation of periosteum-mimicking tissue has become a novel strategy for bone defect repair and regeneration, especially in critical-sized bone defects caused by trauma and bone tumor resection. Here, we utilized a bone morphogenetic protein-2 (BMP-2)-loaded scaffold to create periosteum-like tissue (PT) in vivo, mimicking the mesenchymal condensation during native long bone development. We found that BMP-2-induced endochondral ossification plays an indispensable role in the construction of PTs. Moreover, we confirmed that BMP-2-induced PTs exhibit a similar architecture to the periosteum and harbor abundant functional periosteum-like tissue-derived cells (PTDCs), blood vessels, and osteochondral progenitor cells. Interestingly, we found that the addition of chondroitin sulfate (CS), an essential component of the extracellular matrix (ECM), could further increase the abundance and enhance the function of recruited PTDCs from the PTs and finally increase the regenerative capacity of the PTs in autologous transplantation assays, even in old mice. This novel biomimetic strategy for generating PT through in vivo endochondral ossification deserves further clinical translation.

CBX4-dependent regulation of HDAC3 nuclear translocation reduces Bmp2-induced osteoblastic differentiation and calcification in adamantinomatous craniopharyngioma

Background Calcification of adamantinomatous craniopharyngioma (ACP) often causes problems with tumor resection, leading to a high incidence of deadly complications and tumor recurrence. Histone acetyltransferase (HAT) and histone deacetylase (HDAC) are 2 key enzymes that regulate histone acetylation and play important roles in tumor development. However, the roles of HAT and HDAC in the calcification and osteoblastic differentiation of ACP are not known. Methods In this study, primary cells were isolated from ACP tissues, and calcification was induced with bone morphogenetic protein 2 (Bmp2). HDAC3 expression was assessed in 12 tissue samples by Western blotting and immunohistochemistry. ACP calcification was assessed by Alizarin red staining. A luciferase reporter assay was performed to examine the interaction between miR-181b and the 3’-untranslated region of the polycomb chromobox 4 (CBX4) gene. Results Our results showed that the expression of HDAC3 was increased in the calcified ACP samples, but inhibition of HDAC3 promoted ACP cell calcification and osteoblastic differentiation. Mechanistically, HDAC3 nuclear translocation was suppressed by Bmp2, leading to Runx2 protein expression and Osterix, osteocalcin (OCN), osteopontin (OPN), and alkaline phosphatase (ALP) mRNA expression. In addition, this process was suppressed by CBX4, which stabilized the nuclear localization of HDAC3. miR-181b, the expression of which was increased in Bmp2-induced ACP cells, directly targeted and decreased CBX4 expression and inhibited the nuclear localization of HDAC3. Conclusions Our results demonstrate that Bmp2 increases miR-181b levels to directly target and inhibit CBX4 expression, leading to a reduction in the CBX4-dependent regulation of HDAC3 nuclear translocation, which results in Runx2 activation/osteoblastic differentiation and calcium deposition in ACP. Further studies targeting these cascades may contribute to therapeutic interventions used for recurrent ACP.

Therapeutic Mechanism of Chinese Medicine on the Healing of Early and Middle Fractures in Rabbits Under the Expression Level of Bone Morphogenetic Protein-2 (BMP-2) in Bone Tissue

In order to explore the therapeutic mechanism of Chinese medicine on the healing of rabbits early and middle fractures, a rabbit fracture model was established in this study. The study was divided into several groups, i.e., treatment group (TG) (fed with Chinese medicine Capsule) and control group (CG) (fed with normal saline (NS)). The materials were collected at 1, 3, and 5 weeks after the start of the experiment for analysis. The experiment content included: callus Hematoxylin-Eosin staining (HE staining); Bone Morphogenetic protein-2 (BMP-2) protein level detection; Type I and type II bone collagen (BC) detection; and serum biochemical factors detection. The experimental results showed that the formation of callus in the TG was better than in the CG; the BMP-2 protein expression level in the TG was higher than in the CG, and there were statistically significant differences (SSDs); the type I and type II BC levels in the TG were higher than the CG, there were SSDs; the levels of serum calcium (SC), phosphorus ion (PI), and alkaline phosphatase (ALP) in the TG were also higher than in the CG, and there were SSDs.