24,25-Dihydroxyvitamin D3 cooperates with a stable, fluoromethylene LPA receptor agonist to secure human (MG63) osteoblast maturation

Ternary nanocomposite potentiates the lysophosphatidic acid effect on human osteoblast (MG63) maturation

Aim: This study aimed to investigate the potential of ternary nanocomposite (TNC) to support MG63 osteoblast maturation to EB1089-(3S)1-fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate (FHBP) cotreatment. Materials & methods: Binary (P25/reduced graphene oxide [rGO]) nanocomposite was prepared, and silver (Ag) nanoparticles were loaded onto the surface to form TNC (P25/rGO/Ag). The influence of TNC on proliferation, alkaline phosphatase activity and osteogenic gene expression was evaluated in a model of osteoblast maturation wherein MG63 were costimulated with EB1089 and FHBP. Results: TNC had no cytotoxic effect on MG63. The addition of TNC to EB1089-FHBP cotreatment enhanced the maturation of MG63, as supported by the greater alkaline phosphatase activity and OPN and OCN gene expression. Conclusion: TNC could serve as a promising carrier for FHBP, opening up possibilities for its application in bone regeneration.

Puerarin improves OVX-induced osteoporosis by regulating phospholipid metabolism and biosynthesis of unsaturated fatty acids based on serum metabolomics

BACKGROUND

Postmenopausal osteoporosis (PMOP) is a serious problem for the women over 50 years old. Natural product puerarin (PUE) has been proven to improve PMOP with high safety. PMOP is a metabolic disorder affecting bone metabolism, indicating that endogenous metabolites amelioration may be a novel strategy for PMOP therapy. However, what the metabolic profile of POMP will be after PUE treatment is still obscure.

PURPOSE

We purpose to figure out the metabolic characteristics of PMOP and to explore the intrinsic mechanism on the anti-osteoporosis efficacy after PUE treatment based on the serum metabolomics.

METHODS

We established OVX rats as osteoporosis model, and the animals were distributed into Sham, OVX, and OVX+PUE (100 mg/kg/d) group. The femurs were analyzed by μ-CT and three-point bending test. Serum metabolomics was performed by UPLC/Q-TOF-MS. We also determined the body weight, liver weight, and the levels of serum TC, TG, LDL-C, and HDL-C. The key proteins of the PPARγ pathway and Wnt pathway were analyzed by Western blot and qPCR experiments.

RESULTS

PUE treatment for 14 weeks both improved the bone structure and ameliorated lipid metabolism in ovariectomized rats. By determination and further analysis of serum metabolomics, we revealed that the endogenous metabolites was significantly changed in ovariectomized rats, and PUE treatment adjusted 23 differential metabolites, which were involved in phospholipid metabolism metabolism and PUFAs metabolic pathways. Close correlationships were futher found between the indexes of bone metabolism, lipid metabolism and the differential metabolites, particularly LysoPA, S1P and n-3/n-6 PUFAs. Further, we discovered that PUE regulated differentiation of BMSCs to elicit anti-osteoporosis efficacy, attributing to Wnt/β-catenin signaling activation and PPARγ pathway inhibition initiated by metabolomics.

CONCLUSION

PUE improves OVX-induced osteoporosis and lipid metabolism by regulating phospholipid metabolism and biosynthesis of PUFAs, resulting in reducing the adipogenic differentiation and promoting osteogenic differentiation of BMSCs via Wnt pathway activation and PPARγ pathway inhibition in ovariectomized rats. The study provides us a novel mechanism to explain the improvement of osteoporosis by PUE, depicts a metabolic profile of PMOP, and gives us another point cut for further exploring the pathogenesis of PMOP and looking for biomarkers of osteoporosis.

Development of a facile fluorophosphonate-functionalised titanium surface for potential orthopaedic applications

Background

Aseptic loosening of total joint replacements (TJRs) continues to be the main cause of implant failures. The socioeconomic impact of surgical revisions is hugely significant; in the United Kingdom alone, it is estimated that £137 m is spent annually on revision arthroplasties. Enhancing the longevity of titanium implants will help reduce the incidence and overall cost of failed devices.

Methods

In realising the development of a superior titanium technology, we exploited the natural affinity of titanium for phosphonic acids and developed a facile means of coating the metal with (3S)1-fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate (FHBP), a phosphatase-resistant analogue of lysophosphatidic acid (LPA). Importantly LPA and selected LPA analogues like FHBP synergistically cooperate with calcitriol to promote human osteoblast formation and maturation.

Results

Herein, we provide evidence that simply immersing titanium in aqueous solutions of FHBP afforded a surface that was superior to unmodified metal at enhancing osteoblast maturation. Importantly, FHBP-functionalised titanium remained stable to 2 years of ambient storage, resisted ∼35 kGy of gamma irradiation and survived implantation into a bone substitute (Sawbone™) and irrigation.

Conclusion

The facile step we have taken to modify titanium and the robustness of the final surface finish are appealing properties that are likely to attract the attention of implant manufacturers in the future.

The translational potential of this article

We have generated a functionalised titanium (Ti) surface by simply immersing Ti in aqueous solutions of a bioactive lipid. As a facile procedure it will have greater appeal to implant manufacturers compared to onerous and costly developmental processes.

Polydopamine-Lysophosphatidate-Functionalised Titanium: A Novel Hybrid Surface Finish for Bone Regenerative Applications

Aseptic loosening of total joint replacements (TJRs) continues to be the main cause of implant failures. The socioeconomic impact of surgical revisions is hugely significant; in the United Kingdom alone, it is estimated that £135m is spent annually on revision arthroplasties. Enhancing the longevity of titanium implants will help reduce the incidence and overall cost of failed devices. In realising the development of a superior titanium (Ti) technology, we took inspiration from the growing interest in reactive polydopamine thin films for biomaterial surface functionalisations. Adopting a "one-pot" approach, we exposed medical-grade titanium to a mildly alkaline solution of dopamine hydrochloride (DHC) supplemented with (3S)1-fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate (FHBP), a phosphatase-resistant analogue of lysophosphatidic acid (LPA). Importantly, LPA and selected LPA analogues like FHBP synergistically cooperate with calcitriol to promote human osteoblast formation and maturation. Herein, we provide evidence that simply immersing Ti in aqueous solutions of DHC-FHBP afforded a surface that was superior to FHBP-Ti at enhancing osteoblast maturation. The facile step we have taken to modify Ti and the biological performance of the final surface finish are appealing properties that may attract the attention of implant manufacturers in the future.

Lysophosphatidic acid: Its role in bone cell biology and potential for use in bone regeneration

Lysophosphatidic acid (LPA) is a simple phospholipid that exerts pleiotropic effects on numerous cell types by activating its family of cognate G protein-coupled receptors (GPCRs) and participates in many biological processes, including organismal development, wound healing, and carcinogenesis. Bone cells, such as bone marrow mesenchymal stromal (stem) cells (BMSCs), osteoblasts, osteocytes and osteoclasts play essential roles in bone homeostasis and repair. Previous studies have identified the presence of specific LPA receptors in these bone cells. In recent years, an increasing number of cellular effects of LPA, such as the induction of cell proliferation, survival, migration, differentiation and cytokine secretion, have been found in different bone cells. Moreover, some biomaterials containing LPA have shown the ability to enhance osteogenesis. This review will focus on findings associated with LPA functions in these bone cells and present current studies related to the application of LPA in bone regenerative medicine. Further understanding this information will help us develop better strategies for bone healing.

The Evolutionarily Conserved Cassette Exon 7b Drives ERG's Oncogenic Properties

The oncogene ERG encodes an ETS family transcription factor and is implicated in blood, vascular, and bone development and in prostate, blood, and bone cancer. The ERG gene is alternatively spliced; of particular interest is its cassette exon 7b which adds 24 amino acids, in frame, to the transcriptional activation domain. Higher exon 7b inclusion rates are associated with increased cell proliferation and advanced prostate cancer. The 24 amino acids encoded by exon 7b show evolutionary conservation from humans to echinoderms, highlighting their functional importance. Throughout evolution, these 24 amino acids are encoded by a distinct short exon. Splice-switching oligonucleotides based on morpholino chemistry were designed to induce skipping of ERG exon 7b in MG63 osteosarcoma and VCaP prostate cancer cells. Induction of exon 7b skipping reduced cell proliferation and invasion, increased apoptosis in vitro, and reduced xenograft growth in vivo. We also show that ERG's exon 7b is required for the induction of tissue nonspecific alkaline phosphatase. Together, these findings show that the evolutionarily conserved cassette exon 7b is central to ERG's oncogenic properties.

Development and biological evaluation of fluorophosphonate-modified hydroxyapatite for orthopaedic applications

There is an incentive to functionalise hydroxyapatite (HA) for orthopaedic implant use with bioactive agents to encourage superior integration of the implants into host bone. One such agent is (3S) 1-fluoro-3-hydroxy-4-(oleoyloxy) butyl-1-phosphonate (FHBP), a phosphatase-resistant lysophosphatidic acid (LPA) analogue. We investigated the effect of an FHBP-HA coating on the maturation of human (MG63) osteoblast-like cells. Optimal coating conditions were identified and cell maturation on modified and unmodified, control HA surfaces was assessed. Stress tests were performed to evaluate coating survivorship after exposure to mechanical and thermal insults that are routinely encountered in the clinical environment. MG63 maturation was found to be three times greater on FHBP-modified HA compared to controls (p < 0.0001). There was no significant loss of coating bioactivity after autoclaving (P = 0.9813) although functionality declined by 67% after mechanical cleaning and reuse (p < 0.0001). The bioactivity of modified disks was significantly greater than that of controls following storage for up to six months (p < 0.001). Herein we demonstrate that HA can be functionalised with FHBP in a facile, scalable manner and that this novel surface has the capacity to enhance osteoblast maturation. Improving the biological performance of HA in a bone regenerative setting could be realised through the simple conjugation of bioactive LPA species in the future. Depicted is a stylised summary of hydroxyapatite (HA) surface modification using an analogue of lysophosphatidic acid, FHBP. a HA surfaces are simply steeped in an aqueous solution of 2 μM FHBP. b The polar head group of some FHBP molecules react with available hydroxyl residues at the mineral surfaces forming robust HA-O-P bonds leaving acyl chain extensions perpendicular to the HA surface. These fatty acyl chains provide points of integration for other FHBP molecules to facilitate their self-assembly. This final surface finish enhanced the human osteoblast maturation response to calcitriol, the active vitamin D3 metabolite.

Effects of 1,25 and 24,25 Vitamin D on Corneal Epithelial Proliferation, Migration and Vitamin D Metabolizing and Catabolizing Enzymes

This study investigated the effects of 1,25(OH)₂D3 and 24R,25(OH)₂D3 on corneal epithelial cell proliferation, migration, and on the vitamin D activating enzyme CYP27B1 (produces 1,25(OH)₂D3) and inactivating enzyme CYP24A1 (produces 24R,25(OH)₂D3). The role of the vitamin D receptor (VDR) was also examined. In VDR wildtype mouse corneal epithelial cells (WT), 1,25(OH)₂D3 increased CYP24A1 protein expression and decreased CYP27B1 expression. In VDR knockout mouse epithelial cells (KO), 1,25(OH)₂D3 increased CYP24A1 and CYP27B1 protein expression. 1,25(OH)₂D3 did not affect WT cell proliferation, but did stimulate VDR KO cell proliferation. In a human corneal epithelial cell line (HCEC), 1,25(OH)₂D3 increased CYP24A1 mRNA and protein expression. 1,25(OH)₂D3 increased CYP27B1 mRNA levels in HCEC, but had no effect on CYP27B1 protein levels. 1,25(OH)₂D3 inhibited HCEC proliferation and stimulated cell migration in primary human epithelial cells. 24,25(OH)₂D3, on the other hand, increased both CYP24A1 and CYP27B1 protein expression in WT and VDR KO cells, and stimulated cell proliferation in both WT and KO cells. In HCEC, 24,25(OH)₂D3 increased CYP24A1 and CYP27B1 mRNA and protein expression, and stimulated cell migration. In human primary corneal epithelial cells, 24,25(OH)₂D3 stimulated migration. We conclude that 24R,25(OH)₂D3 is likely involved in corneal epithelial cell regulation independent of 1,25(OH)₂D3 or VDR.

Fluorophosphonate-functionalised titanium via a pre-adsorbed alkane phosphonic acid: a novel dual action surface finish for bone regenerative applications

Enhancing vitamin D-induced human osteoblast (hOB) maturation at bone biomaterial surfaces is likely to improve prosthesis integration with resultant reductions in the need for revision arthroplasty consequent to aseptic loosening. Biomaterials that are less appealing to microorganisms implicated in implant failures through infection are also highly desirable. However, finding surfaces that enhance hOB maturation to active vitamin D yet deter bacteria remain elusive. In addressing this, we have sought to bio-functionalise titanium (Ti) with lysophosphatidic acid (LPA) and related, phosphatase-resistant, LPA analogues. The impetus for this follows our discovery that LPA co-operates with active vitamin D3 metabolites to secure hOB maturation in vitro including cells grown upon Ti. LPA has also been found, by others, to inhibit virulence factor production and biofilm formation of the human opportunistic pathogen Pseudomonas aeruginosa. Collectively, selected LPA species might offer potential dual-action surface finishes for contemporary bone biomaterials. In attaching a phosphatase-resistant LPA analogue to Ti we took advantage of the affinity of alkane phosphonic acids for TiO2. Herein, we provide evidence for the facile development of a dual-action Ti surface for potential orthopaedic and dental applications. Successful conjugation of an LPA analogue (3S)1-fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate (FHBP) to the Ti surface was supported through physiochemical characterisation using x-ray photoelectron spectroscopy and secondary ion mass spectrometry. hOB maturation to active vitamin D3 was enhanced for cells grown on FHBP-Ti whilst these same surfaces exhibited clear antiadherent properties towards a clinical isolate of Staphylococcus aureus.

Dual Action of Lysophosphatidate-Functionalised Titanium: Interactions with Human (MG63) Osteoblasts and Methicillin Resistant Staphylococcus aureus

Titanium (Ti) is a widely used material for surgical implants; total joint replacements (TJRs), screws and plates for fixing bones and dental implants are forged from Ti. Whilst Ti integrates well into host tissue approximately 10% of TJRs will fail in the lifetime of the patient through a process known as aseptic loosening. These failures necessitate revision arthroplasties which are more complicated and costly than the initial procedure. Finding ways of enhancing early (osseo)integration of TJRs is therefore highly desirable and continues to represent a research priority in current biomaterial design. One way of realising improvements in implant quality is to coat the Ti surface with small biological agents known to support human osteoblast formation and maturation at Ti surfaces. Lysophosphatidic acid (LPA) and certain LPA analogues offer potential solutions as Ti coatings in reducing aseptic loosening. Herein we present evidence for the successful bio-functionalisation of Ti using LPA. This modified Ti surface heightened the maturation of human osteoblasts, as supported by increased expression of alkaline phosphatase. These functionalised surfaces also deterred the attachment and growth of Staphylococcus aureus, a bacterium often associated with implant failures through sepsis. Collectively we provide evidence for the fabrication of a dual-action Ti surface finish, a highly desirable feature towards the development of next-generation implantable devices.