Advantage of ostarine over raloxifene and their combined treatments for muscle of estrogen-deficient rats

PURPOSE

Selective androgen (ostarine, OST) and estrogen (raloxifene, RAL) receptor modulators with improved tissue selectivity have been developed as alternatives to hormone replacement therapy. We investigated the combined effects of OST and RAL on muscle tissue in an estrogen-deficient rat model of postmenopausal conditions.

METHODS

Three-month-old Sprague Dawley rats were divided into groups: (1) untreated non-ovariectomized rats (Non-OVX), (2) untreated ovariectomized rats (OVX), (3) OVX rats treated with OST, (4) OVX rats treated with RAL, (5) OVX rats treated with OST and RAL. Both compounds were administered in the diet. The average dose received was 0.6 ± 0.1 mg for OST and 11.1 ± 1.2 mg for RAL per kg body weight/day. After thirteen weeks, rat activity, muscle weight, structure, gene expression, and serum markers were analyzed.

RESULTS

OST increased muscle weight, capillary ratio, insulin-like growth factor 1 (Igf-1) expression, serum phosphorus, uterine weight. RAL decreased muscle weight, capillary ratio, food intake, serum calcium and increased Igf-1 and Myostatin expression, serum follicle stimulating hormone (FSH). OST + RAL increased muscle nucleus ratio, uterine weight, serum phosphorus, FSH and luteinizing hormone and decreased body and muscle weight, serum calcium. Neither treatment changed muscle fiber size. OVX increased body and muscle weight, decreased uterine weight, serum calcium and magnesium.

CONCLUSION

OST had beneficial effects on muscle in OVX rats. Side effects of OST on the uterus and serum electrolytes should be considered before using it for therapeutic purposes. RAL and RAL + OST had less effect on muscle and showed endocrinological side effects on pituitary-gonadal axis.

Treatment of osteoporosis using a selective androgen receptor modulator ostarine in an orchiectomized rat model

PURPOSE

The selective androgen receptor modulator ostarine has been shown to have advantageous effects on skeletal tissue properties, reducing muscle wasting and improving physical function in males. However, data on effects in male osteoporosis remain limited. In this study, the effects of ostarine on osteoporotic bone were evaluated in a rat model of male osteoporosis and compared with those of testosterone treatments.

METHODS

Eight-month-old male Sprague-Dawley rats were either non-orchiectomized to serve as a healthy control (Non-Orx, Group 1) or orchiectomized (Orx, Groups 2-6) and then grouped (n = 15/group): (1) Non-Orx, (2) Orx, (3) Ostarine Therapy, (4) Testosterone Therapy, (5) Ostarine Prophylaxis and (6) Testosterone Prophylaxis. Prophylaxis treatments started directly after orchiectomy and continued for 18 weeks, whereas Therapy treatments were initiated 12 weeks after Orx. Ostarine and Testosterone were applied orally at daily doses of 0.4 and 50 mg/kg body weight, respectively. The lumbar vertebral bodies and femora were analyzed using biomechanical, micro-CT, ashing, and gene expression analyses.

RESULTS

Ostarine Prophylaxis showed positive effects in preventing osteoporotic changes in cortical and trabecular bone (femoral trabecular density: 26.01 ± 9.1% vs. 20.75 ± 1.2% in Orx and in L4: 16.3 ± 7.3% vs 11.8 ± 2.9% in Orx); biomechanical parameters were not affected; prostate weight was increased (0.62 ± 0.13 g vs 0.18 ± 0.07 g in Orx). Ostarine Therapy increased solely the cortical density of the femur (1.25 ± 0.03 g/cm3 vs. 1.18 ± 0.04 g/cm3 in Orx); other bone parameters remained unaffected. Testosteron Prophylaxis positively influenced cortical density in femur (1.24 ± 0.05 g/cm3 vs. 1.18 ± 0.04 g/cm3 in Orx); Test. Therapy did not change any bony parameters.

CONCLUSION

Ostarine Prophylaxis could be further investigated as a preventative treatment for male osteoporosis, but an androgenic effect on the prostate should be taken into consideration, and combination therapies with other anti-osteoporosis agents could be considered.

Reduced Cell Adhesion on LightPLAS-Coated Implant Surfaces in a Three-Dimensional Bioreactor System

Most implants used in trauma surgery are made of steel and remain inside the body only temporarily. The strong tissue interaction of such implants sometimes creates problems with their explantation. Modified implant surfaces, which decrease tissue attachment, might allow an easier removal and therefore a better outcome. Such a modification must retain the implant function, and needs to be biocompatible and cost-effective. Here, we used a novel VUV-light (Vacuum-Ultraviolett)-based coating technology (LightPLAS) to generate coated stainless-steel plates. The tested LightPLAS coating only had an average thickness of around 335 nm, making it unlikely to interfere with implant function. The coated plates showed good biocompatibility according to ISO 10993-5 and ISO 10993-12, and reduced cell adhesion after four different time points in a 2D cell culture system with osteoblast-like MG-63 cells. Furthermore, we could show decreased cell adhesion in our 3D cell culture system, which mimics the fluid flow above the implant materials as commonly present in the in vivo environment. This new method of surface coating could offer extended options to design implant surfaces for trauma surgery to reduce cell adhesion and implant ingrowth. This may allow for a faster removal time, resulting in shorter overall operation times, thereby reducing costs and complication rates and increasing patient wellbeing.

Changes of the subchondral bone microchannel network in early osteoarthritis

OBJECTIVE

We have identified a 3D network of subchondral microchannels that connects the deep zone of cartilage to the bone marrow (i.e., cartilage-bone marrow microchannel connectors; CMMC). However, the pathological significance of CMMC is largely unknown. Here, we quantitatively evaluated how the CMMC microarchitecture is related to cartilage condition, as well as regional differences in early idiopathic osteoarthritis (OA).

METHODS

Two groups of cadaveric female human femoral heads (intact cartilage vs early cartilage lesions) were identified, and a biopsy-based high-resolution micro-CT imaging was employed. Subchondral bone (SB) thickness, CMMC number, maximum and minimum CMMC size, and the CMMC morphology were quantified and compared between the two groups. The effect of joint's region and cartilage condition was examined on each dependent variable.

RESULTS

The CMMC number and morphology were affected by region of the joint, but not by cartilage condition. On the other hand, the minimum and maximum CMMC size was changed by both the location on the joint, as well as the cartilage condition. The smallest CMMC were consistently detected at the load-bearing region (LBR) of the joint. Compared to non-pathological subjects, the size of the microchannels was enlarged in early OA, most noticeably at the non-load-bearing region (NLBR) and the peripheral rim (PR) of the femoral head. Furthermore, subchondral bone thinning was observed in early OA as a localized occurrence linked with areas of partial chondral defect.

CONCLUSION

Our data point to an enlargement of the SB microchannel network, and a collective structural deterioration of SB in early idiopathic OA.

A combined treatment with selective androgen and estrogen receptor modulators prevents bone loss in orchiectomized rats

PURPOSE

Enobosarm (EN), a selective androgen receptor modulator and raloxifene (RAL), a selective estrogen receptor modulator, have been shown to improve bone tissue in osteoporotic males. The present study evaluated the effects of a combination therapy of EN and RAL on bone properties in orchiectomized rats compared to the respective single treatments.

METHODS

Eight-month-old male Sprague-Dawley rats were either left intact (Non-Orx) or orchiectomized (Orx). The Orx rats were divided into four groups (n = 15 each): 1) Orx, 2) EN treatment (Orx + EN), 3) RAL treatment (Orx + RAL), 4) combined treatment (Orx + EN + RAL). EN and RAL (0.4 mg and 7 mg/kg body weight/day) were applied immediately after Orx with a soy-free pelleted diet for up to 18 weeks. The lumbar spine and femora were examined by micro-CT, biomechanical, histomorphological, ashing, and gene expression analyses.

RESULTS

EN exhibited an anabolic effect on bone, improving some of its parameters in Orx rats, but did not affect biomechanical properties. RAL exhibited antiresorptive activity, maintaining the biomechanical and trabecular parameters of Orx rats at the levels of Non-Orx rats. EN + RAL exerted a stronger effect than the single treatments, improving most of the bone parameters. Liver weight increased after all treatments; the kidney, prostate, and levator ani muscle weights increased after EN and EN + RAL treatments. BW was reduced due to a decreased food intake in the Orx + RAL group and due a reduced visceral fat weight in the Orx + EN + RAL group.

CONCLUSION

The EN + RAL treatment appeared to be promising in preventing male osteoporosis, but given the observed side effects on liver, kidney, and prostate weights, it requires further investigation.

Osteogenic Effect of Pregabalin in Human Primary Mesenchymal Stem Cells, Osteoblasts, and Osteosarcoma Cells

Seventy million patients worldwide are suffering from epilepsy. The long-term use of antiepileptic drugs causes the alteration of the bone tissue and its metabolism, thus increasing the risk of fractures. Clinical and pre-clinical studies have highlighted conflicting data on the influence of the relatively new antiepileptic drug pregabalin (Lyrica^®). The objective of the present study was therefore to investigate its cytotoxicity in primary human osteoblasts (hOB). HOB and human mesenchymal stem cells (hMSC) were isolated from patients. The human osteosarcoma cells MG63 were included as established cell line. Cells were incubated with pregabalin at concentrations ranging from 0 to 40 μg/mL. Time-dependent cell proliferation was measured by automatic cell counting, and metabolism was determined by XTT assay and osseous differentiation by alkaline phosphatase (ALP) activity. Histological examinations of calcium deposit were performed with ALP, Alizarin Red, and von Kossa staining. A concentration-dependent increase in the proliferation of hOB and hMSC was observed after treatment with pregabalin. All cells showed a significant increase in cell metabolism. The osteogenic differentiation, confirmed by the increase of calcium deposit, was promoted by the administration of pregabalin. This effect was already significant at the therapeutic plasma concentration of pregabalin (10 μg/mL). In contrast to the other antiepileptic drugs, pregabalin showed no osteocatabolic effects. Conflicting in-vivo data must therefore be attributed to systemic effects of pregabalin.

The HIFα-Stabilizing Drug Roxadustat Increases the Number of Renal Epo-Producing Sca-1+ Cells

Inhibition of the prolyl-4-hydroxylase domain (PHD) enzymes, leading to the stabilization of hypoxia-inducible factor (HIF) α as well as to the stimulation of erythropoietin (Epo) synthesis, is the functional mechanism of the new anti-anemia drug roxadustat. Little is known about the effects of roxadustat on the Epo-producing cell pool. To gain further insights into the function of PHD inhibitors, we characterized the abundance of mesenchymal stem cell (MSC)-like cells after roxadustat treatment of mice. The number of Sca-1⁺ mesenchymal cells following roxadustat treatment increased exclusively in the kidneys. Isolated Sca-1⁺ cells demonstrated typical features of MSC-like cells, including adherence to tissue culture plates, trilineage differentiation potential, and expression of MSC markers. Kidney-derived Sca-1⁺ MSC-like cells were cultured for up to 21 days. Within the first few days in culture, cells stabilized HIF-1α and HIF-2α and temporarily increased Epo production upon incubation in hypoxia. In summary, we have identified a Sca-1⁺ MSC-like cell population that is involved in renal Epo production and might contribute to the strong anti-anemic effect of the PHD inhibitor roxadustat.

Extracellular Vesicles Allow Epigenetic Mechanotransduction between Chondrocytes and Osteoblasts

MicroRNAs (miRNAs) can be transported in extracellular vesicles (EVs) and are qualified as possible messengers for cell–cell communication. In the context of osteoarthritis (OA), miR-221-3p has been shown to have a mechanosensitive and a paracrine function inside cartilage. However, the question remains if EVs with miR-221-3p can act as molecular mechanotransducers between cells of different tissues. Here, we studied the effect of EV-mediated transport in the communication between chondrocytes and osteoblasts in vitro in a rat model. In silico analysis (Targetscan, miRWalk, miRDB) revealed putative targets of miRNA-221-3p (CDKN1B/p27, TIMP-3, Tcf7l2/TCF4, ARNT). Indeed, transfection of miRNA-221-3p in chondrocytes and osteoblasts resulted in regulation of these targets. Coculture experiments of transfected chondrocytes with untransfected osteoblasts not only showed regulation of these target genes in osteoblasts but also inhibition of their bone formation capacity. Direct treatment with chondrocyte-derived EVs validated that chondrocyte-produced extracellular miR-221-3p was responsible for this effect. Altogether, our study provides a novel perspective on a possible communication pathway of a mechanically induced epigenetic signal through EVs. This may be important for processes at the interface of bone and cartilage, such as OA development, physiologic joint homeostasis, growth or fracture healing, as well as for other tissue interfaces with differing biomechanical properties.

Predicting the disaster - The role of CRP in acetabular surgery

OBJECTIVES

Acetabular fractures represent a complex surgical challenge. Given the heterogenous fracture pattern, the patient characteristics and spectrum of complications demand individual solutions. Surgical site infections (SSI) threaten osteosynthesis, and early detection of them and treatment remain crucial. What is the value of postoperative C-reactive protein (CRP) in this group of patients as well as its normal course?

DESIGN & METHODS

115 patients with isolated fractures of the acetabulum were retrospectively evaluated. CRP, white blood cell count (WBC) and fracture patterns as well as patient characteristics were assessed for 20 days following operative fixation of the acetabular fracture (n = 71) and in fractures that were managed conservatively (n = 44).

RESULTS

Twelve patients suffered an infectious complication. With a one-phase decay, 70.55% of the variance of postoperative CRP kinetics was predicted. To anticipate maximum CRP as well as an infection, the preoperative CRP represented the best prognostic parameter. To predict an infection, the single variable "peak CRP value above 100 mg/l" resulted in a sensitivity and specificity of 91.67% and 36.21%, respectively. Combining a second peak of CRP with maximum CRP and day 5 CRP value for receiver-operating characteristic (ROC) analysis resulted in 83.3% and 88.1%, respectively.

CONCLUSIONS

Predicting surgical site infections after an acetabular fracture is most predictive when analyzing the maximum overall CRP, the second peak and the CRP after day 5. With a combination of these parameters, a sensitivity and specificity of 83.3% and 88.1% to detect an infection was achieved.

Laser Ablated Periodic Nanostructures on Titanium and Steel Implants Influence Adhesion and Osteogenic Differentiation of Mesenchymal Stem Cells

Metal implants used in trauma surgeries are sometimes difficult to remove after the completion of the healing process due to the strong integration with the bone tissue. Periodic surface micro- and nanostructures can directly influence cell adhesion and differentiation on metallic implant materials. However, the fabrication of such structures with classical lithographic methods is too slow and cost-intensive to be of practical relevance. Therefore, we used laser beam interference ablation structuring to systematically generate periodic nanostructures on titanium and steel plates. The newly developed laser process uses a special grating interferometer in combination with an industrial laser scanner and ultrashort pulse laser source, allowing for fast, precise, and cost-effective modification of metal surfaces in a single step process. A total of 30 different periodic topologies reaching from linear over crossed to complex crossed nanostructures with varying depths were generated on steel and titanium plates and tested in bone cell culture. Reduced cell adhesion was found for four different structure types, while cell morphology was influenced by two different structures. Furthermore, we observed impaired osteogenic differentiation for three structures, indicating reduced bone formation around the implant. This efficient way of surface structuring in combination with new insights about its influence on bone cells could lead to newly designed implant surfaces for trauma surgeries with reduced adhesion, resulting in faster removal times, reduced operation times, and reduced complication rates.

Effect of Strontium Ranelate on the Muscle and Vertebrae of Ovariectomized Rats

Osteoporosis is often accompanied by sarcopenia. The effect of strontium ranelate (SR) on muscle tissue has not been investigated sufficiently. In this study, the effect of different SR treatments on muscle was studied. Additionally, the lumbar vertebrae were analyzed. Three-month-old female rats were divided into five groups (n = 12): Group 1: untreated (NON-OVX); Group 2: ovariectomized and left untreated (OVX); Group 3: SR after OVX until the study ended (13 weeks, SR prophylaxis and therapy = pr+th); Group 4: OVX and SR for 8 weeks (SR prophylaxis = pr); Group 5: SR for 5 weeks from the 8 week after OVX (SR therapy = SR th). SR was applied in food (630 mg/kg body weight). The size of muscle fibers, capillary density, metabolic enzymes, and mRNA expression were assessed in soleus, gastrocnemius, and longissimus muscles. The vertebral bodies underwent micro-CT, biomechanical, and ashing analyses. In general, SR did not alter the muscle histological parameters. The changes in fiber size and capillary ratio were related to the body weight. Myostatin mRNA was decreased in Sr pr+th; protein expression was not changed. SR th led to increase in mRNA expression of vascular endothelial growth factor (Vegf-B). In lumbar spine, SR pr+th enhanced biomechanical properties, bone mineral density, trabecular area, density, and thickness and cortical density. The reduced calcium/phosphate ratio in the SR pr+th group indicates the replacement of calcium by strontium ions. SR has no adverse effects on muscle tissue and it shows a favorable time-dependent effect on vertebrae. A functional analysis of muscles could verify these findings.

Enhanced Production of Exosome-Associated AAV by Overexpression of the Tetraspanin CD9

Research on cell-free vesicles revealed a multitude of characteristics, in particular of microvesicles and exosomes, that range from their potential as biomarkers to a function in horizontal transfer of genetic information from cell to cell and also include supportive functions in viral infection. Exosome-associated adeno-associated viruses (exo-AAVs) are of particular interest for the past couple of years, because they introduced a new source of highly potent recombinant AAVs with improved features, including accelerated transduction rates and more efficient immune escape. However, key factors like the mode of action, efficiency of production, or engineering of exo-AAVs remain elusive to a large extent. Here, we used the established system of CD9 overexpression to boost the exosome output of AAV producing HEK-AAV cells. The CD9-powered high-exosome environment was established during exo-AAV1 production, and we could demonstrate that the yield of exo-AAVs dramatically increased when compared to standard exo-AAVs. Furthermore, we report that exo-AAV-CD9_GFP was more efficient in transduction of cells in the same titer ranges as standard exo-AAVs. Our results provide a technological approach for the generation of exo-AAVs with superior performance.

Identification and characterization of human xylosyltransferase II promoter single nucleotide variants

The human isoenzymes xylosyltransferase-I and -II (XT-I, XT-II) catalyze the rate-limiting step in proteoglycan biosynthesis. Therefore, serum XT activity, mainly representing XT-II activity, displays a powerful biomarker to quantify the actual proteoglycan synthesis rate. Serum XT activity is increased up to 44% in disorders which are characterized by an altered proteoglycan metabolism, whereby underlying regulatory mechanisms remain unclear. The aim of this study was to investigate new regulatory pathways by identifying and characterizing naturally occurring XYLT2 promoter sequence variants as well as their potential influence on promoter activity and serum XT activity. XYLT2 promoter single nucleotide variants (SNVs) were identified and genotyped in the genomic DNA of 100 healthy blood donors by promoter amplification and sequencing or restriction fragment length polymorphism analysis. The SNVs were characterized by an in silico analysis considering genetic linkage and transcription factor binding sites (TBSs). The influence of SNVs on promoter activity and serum XT activity was determined by dual luciferase reporter assay and HPLC-ESI mass spectrometry. Allele frequencies of seven XYLT2 promoter sequence variants identified were investigated. In silico analyses revealed a strong genetic linkage of SNVs c.-80delG and c.-188G > A, c.-80delG and c.-1443G > A, as well as c.-188G > A and c.-1443G > A. However, despite the generation of several SNV-associated changes in TBSs in silico, XYLT2 promoter SNVs did not significantly affect promoter activity. Serum XT activities of SNV carriers deviated up to 8% from the wild-type, whereby the differences were also not statistically significant. This is the first study which identifies, genotypes and characterizes XYLT2 promoter SNVs. Our results reveal a weak genetic heterogeneity and a strong conservation of the human XYLT2 promoter region. Since the SNVs detected could be excluded as causatives for strong interindividual variabilities in serum XT activity, our data provide increasing evidence that XT-II activity is obviously regulated by hitherto unknown complex genetic pathways, such as cis- or trans-acting enhancers, silencers or miRNAs.

First description of the complete human xylosyltransferase-I promoter region

BACKGROUND

Human xylosyltransferase-I (XT-I) catalyzes the rate-limiting step in proteoglycan glycosylation. An increase in XYLT1 mRNA expression and serum XT activity is associated with diseases characterized by abnormal extracellular matrix accumulation like, for instance, fibrosis. Nevertheless, physiological and pathological mechanisms of transcriptional XT regulation remain elusive.

RESULTS

To elucidate whether promoter variations might affect the naturally occurring variability in serum XT activity, a complete sequence analysis of the XYLT1 promoter was performed in genomic DNA of healthy blood donors. Based on promoter amplification by a specialized PCR technique, sequence analysis revealed a fragment of 238 bp, termed XYLT1 238*, which has never been described in the human XYLT1 reference sequence so far. In silico characterization of this unconsidered fragment depicted an evolutionary conservation between sequences of Homo sapiens and Pan troglodytes (chimpanzee) or Mus musculus (mouse), respectively. Promoter activity studies indicated that XYLT1 238* harbors various transcription factor binding sites affecting basal XYLT1 expression and inducibility by transforming growth factor-β1, the key fibrotic mediator. A microsatellite and two single nucleotide variants (SNV), c.-403C>T and c.-1088C>A, were identified and genotyped in 100 healthy blood donors. Construct associated changes in XYLT1 promoter activity were detected for several sequence variants, whereas serum XT activity was only marginally affected.

CONCLUSIONS

Our findings describe for the first time the entire XYLT1 promoter sequence and provide new insights into transcriptional regulation of XT-I. Future studies should analyze the impact of regulatory XYLT1 promoter variations on XT-associated diseases.