Nanohydroxyapatite (nHAp) Doped with Iron Oxide Nanoparticles (IO), miR-21 and miR-124 Under Magnetic Field Conditions Modulates Osteoblast Viability, Reduces Inflammation and Inhibits the Growth of Osteoclast - A Novel Concept for Osteoporosis Treatment: Part 1

Purpose

Osteoporosis results in a severe decrease in the life quality of many people worldwide. The latest data shows that the number of osteoporotic fractures is becoming an increasing international health service problem. Therefore, a new kind of controllable treatment methods for osteoporotic fractures is extensively desired. For that reason, we have manufactured and evaluated nanohydroxyapatite (nHAp)-based composite co-doped with iron oxide (IO) nanoparticles. The biomaterial was used as a matrix for the controlled delivery of miR-21-5p and miR-124-3p, which have a proven impact on bone cell metabolism.

Methods

The nanocomposite Ca₅(PO₄)₃OH/Fe₃O₄ (later called nHAp/IO) was obtained by the wet chemistry method and functionalised with microRNAs (nHAp/IO@miR-21/124). Its physicochemical characterization was performed using XRPD, FT-IR, SEM-EDS and HRTEM and SAED methods. The modulatory effect of the composite was tested in vitro using murine pre-osteoblasts MC3T3-E1 and pre-osteoclasts 4B12. Moreover, the anti-inflammatory effects of biomaterial were analysed using a model of LPS-treated murine macrophages RAW 264.7. We have analysed the cells’ viability, mitochondria membrane potential and oxidative stress under magnetic field (MF+) and without (MF-). Moreover, the results were supplemented with RT-qPCR and Western blot assays to evaluate the expression profile for master regulators of bone metabolism.

Results

The results indicated pro-osteogenic effects of nHAp/IO@miR-21/124 composite enhanced by exposure to MF. The enhanced osteogenesis guided by nHAp/IO@miR-21/124 presence was associated with increased metabolism of progenitor cells and activation of osteogenic markers (Runx-2, Opn, Coll-1). Simultaneously, nanocomposite decreased metabolism and differentiation of pre-osteoclastic 4B12 cells accompanied by reduced expression of CaII and Ctsk. Obtained composite regulated viability of bone progenitor cells and showed immunomodulatory properties inhibiting the expression of inflammatory markers, ie, TNF-α, iNOs or IL-1β, in LPS-stimulated RAW 264.7 cells.

Conclusion

We have described for the first time a new concept of osteoporosis treatment based on nHAp/IO@miR-21/124 application. Obtained results indicated that fabricated nanocomposite might impact proper regeneration of osteoporotic bone, restoring the balance between osteoblasts and osteoclast.

Titanium Dioxide Thin Films Obtained by Atomic Layer Deposition Promotes Osteoblasts' Viability and Differentiation Potential While Inhibiting Osteoclast Activity-Potential Application for Osteoporotic Bone Regeneration

Atomic layer deposition (ALD) technology has started to attract attention as an efficient method for obtaining bioactive, ultrathin oxide coatings. In this study, using ALD, we have created titanium dioxide (TiO2) layers. The coatings were characterised in terms of physicochemical and biological properties. The chemical composition of coatings, as well as thickness, roughness, wettability, was determined using XPS, XRD, XRR. Cytocompatibillity of ALD TiO2 coatings was accessed applying model of mouse pre-osteoblast cell line MC3T3-E1. The accumulation of transcripts essential for bone metabolism (both mRNA and miRNA) was determined using RT-qPCR. Obtained ALD TiO2 coatings were characterised as amorphous and homogeneous. Cytocompatibility of the layers was expressed by proper morphology and growth pattern of the osteoblasts, as well as their increased viability, proliferative and metabolic activity. Simultaneously, we observed decreased activity of osteoclasts. Obtained coatings promoted expression of Opn, Coll-1, miR-17 and miR-21 in MC3T3-E1 cells. The results are promising in terms of the potential application of TiO2 coatings obtained by ALD in the field of orthopaedics, especially in terms of metabolic- and age-related bone diseases, including osteoporosis.

Theranostic Applications of Nanostructured Silicate-Substituted Hydroxyapatite Codoped with Eu3+ and Bi3+ Ions-A Novel Strategy for Bone Regeneration

In this paper, nanocrystalline silicate-substituted hydroxyapatites (nSi-HAps) codoped with Eu³⁺ were functionalized with Bi³⁺ ions. Biomaterials were synthesized using a microwave-assisted hydrothermal method and heat-treated at 700 °C. The concentration of Eu³⁺ ions was established at 1 mol %, and the concentration of Bi³⁺ was in the range of 0.5-2 mol %. The physicochemical properties of the obtained biomaterials were determined using previously established methods, including X-ray powder diffraction, scanning electron microscopy techniques, and IR spectroscopy. Particle sizes obtained in this study were in the range of 22-65 nm, which was established by the Rietveld method. The luminescence properties of the Eu³⁺ ion-doped silicate-substituted apatite were recorded depending on the bismuth(III) concentration. The cytocompatibility of obtained biomaterials was tested using the model of mouse pre-osteoblasts cell line, that is, MC3T3-E1. We showed that the obtained biomaterials exerted anti-apoptotic effect, reducing the number of early and late apoptotic cells and decreasing caspase activity and reactive oxygen species accumulation. The transcripts levels of genes associated with apoptosis confirmed the anti-apoptotic effect of the biomaterials. Increased metabolic activity of MC3T3-E1 in cultures with biomaterials functionalized with Bi³⁺ ions has been observed. Moreover, the determined profile of osteogenic markers indicates that the obtained matrices, that is, Eu³⁺:nSi-HAp functionalized with Bi³⁺ ions, exert pro-osteogenic properties. The biological features of Eu³⁺:nSi-HAp modified with Bi³⁺ ions are highly desired in terms of functional tissue restoration and further efficient osteointegration.

Small and Long Non-coding RNAs as Functional Regulators of Bone Homeostasis, Acting Alone or Cooperatively

Emerging knowledge indicates that non-coding RNAs, including microRNAs (miRNAs) and long-noncoding RNAs (lncRNAs), have a pivotal role in bone development and the pathogenesis of bone-related disorders. Most recently, miRNAs have started to be regarded as potential biomarkers or targets for various sets of diseases, while lncRNAs have gained attention as a new layer of gene expression control acting through versatile interactions, also with miRNAs. The rapid development of RNA sequencing techniques based on next-generation sequencing (NGS) gives us better insight into molecular pathways regulated by the miRNA-lncRNA network. In this review, we summarize the current knowledge related to the function of miRNAs and lncRNAs as regulators of genes that are crucial for proper bone metabolism and homeostasis. We have characterized important non-coding RNAs and their expression signatures, in relationship to bone. Analysis of the biological function of miRNAs and lncRNAs, as well as their network, will pave the way for a better understanding of the pathogenesis of various bone disorders. We also think that this knowledge may lead to the development of innovative diagnostic tools and therapeutic approaches for bone-related disorders.

Zirconium Oxide Thin Films Obtained by Atomic Layer Deposition Technology Abolish the Anti-Osteogenic Effect Resulting from miR-21 Inhibition in the Pre-Osteoblastic MC3T3 Cell Line

Introduction

The development of the field of biomaterials engineering is rapid. Various bioactive coatings are created to improve the biocompatibility of substrates used for bone regeneration, which includes formulation of thin zirconia coatings with pro-osteogenic properties. The aim of this study was to assess the biological properties of ZrO₂ thin films grown by Atomic Layer Deposition (ALD) technology (ZrO₂^ALD).

Methodology

The cytocompatibility of the obtained layers was analysed using the mice pre-osteoblastic cell line (MC3T3) characterized by decreased expression of microRNA 21-5p (miR-21-5p) in order to evaluate the potential pro-osteogenic properties of the coatings. The in vitro experiments were designed to determine the effect of ZrO₂^ALD coatings on cell morphology (confocal microscope), proliferative activity (cell cycle analysis) and metabolism, reflected by mitochondrial membrane potential (cytometric-based measurement). Additionally, the influence of layers on the expression of genes associated with cell survival and osteogenesis was studied using RT-qPCR. The following genes were investigated: B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), p53 and p21, as well as osteogenic markers, i.e. collagen type 1 (Coll-1), osteopontin (Opn), osteocalcin (Ocl) and runt-related transcription factor 2 (Runx-2). The levels of microRNA (miRNA/miR) involved in the regulation of osteogenic genes were determined, including miR-7, miR-21, miR-124 and miR-223.

Results

The analysis revealed that the obtained coatings are cytocompatible and may increase the metabolism of pre-osteoblast, which was correlated with increased mitochondrial membrane potential and extensive development of the mitochondrial network. The obtained coatings affected the viability and proliferative status of cells, reducing the population of actively dividing cells. However, in cultures propagated on ZrO₂^ALD coatings, the up-regulation of genes essential for bone metabolism was noted.

Discussion

The data obtained indicate that ZrO₂ coatings created using the ALD method may have pro-osteogenic properties and may improve the metabolism of bone precursor cells. Given the above, further development of ZrO₂^ALD layers is essential in terms of their potential clinical application in bone regenerative medicine.

Three dimensional (3D) printed polylactic acid with nano-hydroxyapatite doped with europium(III) ions (nHAp/PLLA@Eu3+) composite for osteochondral defect regeneration and theranostics

In the current research previously developed composites composed from poly (l-lactide) (PLLA) and nano-hydroxyapatite (10 wt% nHAp/PLLA) were functionalized with different concentrations of europium (III) (Eu³⁺). The aim of this study was to determine whether Eu³⁺ ions doped within the 10 wt% nHAp/PLLA scaffolds will improve the bioactivity of composites. Therefore, first set of experiments was designed to evaluate the effect of Eu³⁺ ions on morphology, viability, proliferation and metabolism of progenitor cells isolated from adipose tissue (hASC). Three different concentration were tested i.e. 1 mol%, 3 mol% and 5%mol. We identified the 10 wt% nHAp/PLLA@3 mol% Eu³⁺ scaffolds as the most cytocompatible. Further, we investigated the influence of the composites doped with 3 mol% Eu³⁺ ions on differentiation of hASC toward bone and cartilage forming cells. Our results showed that 10 wt% nHAp/PLLA@3 mol% Eu³⁺ scaffolds promotes osteogenesis and chondrogenesis of hASCs what was associated with improved synthesis and secretion of extracellular matrix proteins specific for bone and articular cartilage tissue. We also proved that obtained biomaterials have bio-imaging function and their integration with bone can be monitored using micro computed tomography (μCT).

The Haematococcus pluvialis extract enriched by bioaccumulation process with Mg(II) ions improves insulin resistance in equine adipose-derived stromal cells (EqASCs)

Insulin resistance (IR) is one of the characteristic features of equine metabolic syndrome (EMS). Presently, the only therapies of choice are caloric restrictions combined with mineral supplementation, which might improve insulin sensitivity. In this study we investigated the effect of Haematococcus pluvialis algae water extract enriched in bioaccumulation process in magnesium ions (Hp_Mg(II)) on equine adipose derived mesenchymal stromal stem cells, in which insulin resistance was induced by palmitic acid (IR-EqASCs). For this purpose, chemical characterization of H. pluvialis was performed with special emphasis on the analysis of minerals composition, total phenolic and carotenoids contents, as well as scavenging activity. To examine the influence of H. pluvialis extract on IR-EqASCs, various methods of molecular biology and microscopic observations (i.e., immunofluorescence staining, SEM, gene expression by RT-qPCR, proliferative and metabolic cells activity analysis) were applied to investigate in vitro viability, oxidative stress markers and apoptosis-related factor accumulation, along with insulin resistance-related genes expression. Obtained results show, that Hp_Mg(II) significantly improves proliferative and metabolic activity of IR-EqASCs, shortens their population doubling time, improves their clonogenic potential and reduces expression of apoptosis related genes. Moreover, anti-oxidative effect of extract was presented.

Metformin Increases Proliferative Activity and Viability of Multipotent Stromal Stem Cells Isolated from Adipose Tissue Derived from Horses with Equine Metabolic Syndrome

In this study, we investigated the influence of metformin (MF) on proliferation and viability of adipose-derived stromal cells isolated from horses (EqASCs). We determined the effect of metformin on cell metabolism in terms of mitochondrial metabolism and oxidative status. Our purpose was to evaluate the metformin effect on cells derived from healthy horses (EqASCHE) and individuals affected by equine metabolic syndrome (EqASCEMS). The cells were treated with 0.5 μM MF for 72 h. The proliferative activity was evaluated based on the measurement of BrdU incorporation during DNA synthesis, as well as population doubling time rate (PDT) and distribution of EqASCs in the cell cycle. The influence of metformin on EqASC viability was determined in relation to apoptosis profile, mitochondrial membrane potential, oxidative stress markers and BAX/BCL-2 mRNA ratio. Further, we were interested in possibility of metformin affecting the Wnt3a signalling pathway and, thus, we determined mRNA and protein level of WNT3A and β-catenin. Finally, using a two-tailed RT-qPCR method, we investigated the expression of miR-16-5p, miR-21-5p, miR-29a-3p, miR-140-3p and miR-145-5p. Obtained results indicate pro-proliferative and anti-apoptotic effects of metformin on EqASCs. In this study, MF significantly improved proliferation of EqASCs, which manifested in increased synthesis of DNA and lowered PDT value. Additionally, metformin improved metabolism and viability of cells, which correlated with higher mitochondrial membrane potential, reduced apoptosis and increased WNT3A/β-catenin expression. Metformin modulates the miRNA expression differently in EqASCHE and EqASCEMS. Metformin may be used as a preconditioning agent which stimulates proliferative activity and viability of EqASCs.

Nanocrystalline Hydroxyapatite Loaded with Resveratrol in Colloidal Suspension Improves Viability, Metabolic Activity and Mitochondrial Potential in Human Adipose-Derived Mesenchymal Stromal Stem Cells (hASCs)

In response to the demand for new multifunctional materials characterized by high biocompatibility, hydrogel (HG) nanocomposites as a platform for bioactive compound delivery have been developed and fabricated. A specific crosslinking/copolymerization chemistry was used to construct hydrogels with a controlled network organization. The hydrogels were prepared using 3,6-anhydro-α-l-galacto-β-d-galactan (galactose hydrogel) together with resveratrol (trans-3,5,4'-trihydroxystilbene) and calcium hydroxyapatite nanoparticles. The resveratrol was introduced in three different concentrations of 0.1, 0.5, and 1 mM. Nanosized calcium hydroxyapatite was synthesized by a microwave-assisted hydrothermal technique, annealed at 500 °C for 3 h, and introduced at a concentration 10% (m/v). The morphology and structural properties of Ca10(PO₄)₆(OH)₂ and its composite were determined by using XRPD (X-ray powder diffraction) techniques, as well as the absorption and IR (infrared) spectroscopy. The average nanoparticle size was 35 nm. The water affinity, morphology, organic compound release profile, and cytocompatibility of the obtained materials were studied in detail. The designed hydrogels were shown to be materials of biological relevance and of great pharmacological potential as carriers for bioactive compound delivery. Their cytocompatibility was tested using a model of human multipotent stromal cells isolated from adipose tissue (hASCs). The biomaterials increased the proliferative activity and viability of hASCs, as well as reduced markers of oxidative stress. In light of the obtained results, it has been thought that the designed materials meet the requirements of the tissue engineering triad, and may find application in regenerative medicine, especially for personalized therapies.

New approach to modification of poly (l-lactic acid) with nano-hydroxyapatite improving functionality of human adipose-derived stromal cells (hASCs) through increased viability and enhanced mitochondrial activity

The aim of this study was to determine the cytocompatibility of poly (l-lactide) (PLLA) scaffolds fabricated using co-rotating twin screw extrusion technique and functionalized with different concentrations of nano-hydroxyapatite (nHAp). The efforts were aimed on the designing bioactive scaffolds improving the viability and metabolic activity of human adipose-derived multipotent stromal cells (hASCs). The in vitro study was designed to determine the optimal nHAp concentration, based on analysis of hASCs morphology, adhesion rate, as well as metabolic and proliferative potential. Initially, the PLLA filled with three different concentrations of the nHAp were tested i.e. 5%, 10% and 15 wt%. The obtained results indicated that the 10 wt% nHAp in the PLLA (10% nHAp/PLLA) matrices improved the adhesion and proliferation of the hASCs, what was in good agreement with the results of tensile properties of the composites. Further, we performed profound studies regarding the cytotoxicity of 10% nHAp/PLLA. The analysis included the evaluation of the biomaterial influence on viability, apoptosis-related markers expression profile and mitochondrial function. The cytocompatibility of 10% nHAp/PLLA scaffolds toward the hASCs was confirmed. The hASCs propagated on 10% nHAp/PLLA were more viable then those propagated on the plain PLLA. The level of pro-apoptotic markers, i.e. caspase-3 and Bax in cultures on 10% nHAp/PLLA was significantly decreased. Obtained results correlated with higher mitochondrial membrane potential of hASCs in those cultures. The obtained composites may improve therapeutic potential of hASCs via directing their adhesion, enhancing proliferation and viability as well as increasing mitochondrial potential, thus may find potential application in tissue engineering.

Metformin Promotes Osteogenic Differentiation of Adipose-Derived Stromal Cells and Exerts Pro-Osteogenic Effect Stimulating Bone Regeneration

Metformin, the gold standard in type 2 diabetes treatment, is a drug with multi-faceted effects. Currently, metformin has gained much attention as an agent that may find application in regenerative medicine. In this study, we considered its pro-osteogenic function in the course of in vitro osteogenesis of multipotent stromal cells derived from rat adipose tissue (rASCs). In addition, we evaluated the effect of metformin treatment on bone metabolism in a model of cranial defect in nondiabetic rats. In vitro study showed that metformin that is introduced to the culture medium at concentration equal 500 µM may promote the differentiation of rASCs into bone-forming cells, which express mRNA and secrets proteins that are related to the functional tissue (namely, alkaline phosphatase and osteocalcin). Osteogenic effect of metformin, as determined using in vitro model, was also manifested with the formation of mineralized extracellular matrix rich calcium and phosphorous deposits. We have also found, that in undifferentiated rASCs, metformin significantly activates a critical regulatory factor for osteogenic differentiation, i.e., AMPK. Moreover, using in vivo model we showed metformin administration at a dose of 250 mg/kg/day accelerated bone healing and the formation of mature tissue at a fracture site in rat cranial defect model. The obtained results shed promising light on metformin application in regenerative orthopedics, both as an agent improving functionality of ASCs for therapeutic transplantation, as well as a medication enhancing the bone healing process.

Fabrication, Characterization, and Cytotoxicity of Thermoplastic Polyurethane/Poly(lactic acid) Material Using Human Adipose Derived Mesenchymal Stromal Stem Cells (hASCs)

Thermoplastic polyurethane (TPU) and poly(lactic acid) are types of biocompatible and degradable synthetic polymers required for biomedical applications. Physically blended (TPU+PLA) tissue engineering matrices were produced via solvent casting technique. The following types of polymer blend were prepared: (TPU+PLA) 7:3, (TPU+PLA) 6:4, (TPU+PLA) 4:6, and (TPU+PLA) 3:7. Various methods were employed to characterize the properties of these polymers: surface properties such as morphology (scanning electron microscopy), wettability (goniometry), and roughness (profilometric analysis). Analyses of hydrophilic and hydrophobic properties, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) of the obtained polymer blends were conducted. Tensile tests demonstrated that the blends exhibited a wide range of mechanical properties. Cytotoxicity of polymers was tested using human multipotent stromal cells derived from adipose tissue (hASC). In vitro assays revealed that (TPU+PLA) 3:7 matrices were the most cytocompatible biomaterials. Cells cultured on (TPU+PLA) 3:7 had proper morphology, growth pattern, and were distinguished by increased proliferative and metabolic activity. Additionally, it appeared that (TPU+PLA) 3:7 biomaterials showed antiapoptotic properties. hASC cultured on these matrices had reduced expression of Bax-α and increased expression of Bcl-2. This study demonstrated the feasibility of producing a biocompatible scaffold form based on (TPU+PLA) blends that have potential to be applied in tissue engineering.

Biological effects of sol-gel derived ZrO2 and SiO2/ZrO2 coatings on stainless steel surface--In vitro model using mesenchymal stem cells

The objective of this study was to determine biocompatibility of zirconia-based coatings obtained by the sol-gel method. Two matrices, ZrO2 and SiO2/ZrO2, were created and applied on stainless steel type 316L with dip-coating technique. The morphology and topography of biomaterials' surface were characterized using energy-dispersive X-ray spectroscopy and atomic force microscopy, while chemical composition was analyzed by Raman spectroscopy. Additionally, wettability and surface free energy were characterized. Biocompatibility of obtained biomaterials was evaluated using an in vitro model employing mesenchymal stem cells (MSCs) of adipose and bone marrow origin. Biological analysis included determination of proliferation activity and morphology of MSCs in cultures on synthesized biomaterials. Osteoinductive properties of biomaterials were determined both in non-osteogenic, as well as osteogenic conditions. The results showed that investigated biomaterials exerted different impact on MSCs. Biomaterial with ZrO2 layer was more biocompatible for adipose-derived MSCs, while SiO2/ZrO2 layer promoted proliferation of bone marrow derived MSCs. Moreover, hybrid coating exhibited greater osteoinductive properties than ZrO2 coating, both on cultures with adipose-derived stromal (stem) cells and bone marrow stromal cells. Observed biological effects may result not only from different chemical composition, but also from diverse wettability. The ZrO2 coating was characterized as hydrophobic layer, while SiO2/ZrO2 exhibited hydrophilic properties. The results obtained suggest that behavior of MSCs in response to the biomaterial may vary depending on their origin, therefore we postulate, that screening analysis of implants' biocompatibility, should incorporate model applying both adipose- and bone marrow derived MSCs.

The influence of static magnetic fields on canine and equine mesenchymal stem cells derived from adipose tissue

The aim of this study was to evaluate the proliferation rate and morphological changes of adipose-derived mesenchymal stem cells of canine and equine origin (Eq- and CaAdMSC). Investigated cells were exposed to a static magnetic field (MF) with the intensity of 0.5 T. Proliferation activity of cells was determined with the Alamar Blue assay. Obtained results, normalized in respect to the control culture, showed that EqAdMSC exposed to MF maintained a high proliferation status, whereas proliferation activity of CaAdMSC cultured in the presence of MF was decreased. Estimations of population doubling time (PDT) also revealed that EqAdMSCs exposed to static MF achieved a twofold increase in the total number of cells in a shorter amount of time than the control culture. The PDT value obtained for investigated CaAdMSCs indicated that MF exposure resulted in the prolongation of population doubling time. Morphology of cells and cellular composition was investigated using a light inverted microscope and a fluorescent microscope. A scanning electron microscope was used for microvesicles (MVs) imaging. Obtained results showed that both cell types maintained fibroblastic morphology and did not reveal signs of apoptosis or necrosis. However, the MF had an influence on the MVs secretion. While EqAdMSCs propagated in the presence of MF were characterized by the abundant MVs presence, CaAdMSCs revealed poor secretory activity. The approach presented provides complex analysis, which enables one to determine changes in equine and canine cytophysiology.