Effects of combined teriparatide and zoledronic acid on posterior lumbar vertebral fusion in an aged ovariectomized rat model of osteopenia

Isolation, purification, and antiosteoporosis activity of donkey bone collagen from discarded bone and its antioxidant peptides

Oxidative stress plays a crucial role in the development of osteoporosis. In this study, it was observed that donkey bone collagen (DC) at a concentration of 500 μg/mL scavenged 17.89 % of 1,1-Diphenyl-2-picrylhydrazyl (DPPH) free radicals, indicating its antioxidant properties. Additionally, when an oxidative damage osteoblast model was created using H2O2, 100 μg/mL DC demonstrated the ability to enhance cell survival by 27.31 %. Furthermore, 50 μg/mL DC increased the intracellular differentiation marker alkaline phosphatase (ALP) level by 62.65 %. Additionally, the study revealed that DC significantly increased the expression of osteoporosis-related factors in serum and effectively restored the abnormal structure of spongy bone in mice osteoporosis model. Peptides (GGWFL, ANLGPA, and GWFK) isolated from DC through gastrointestinal digestion and subsequent enzymatic purification in vitro demonstrated the ability to safeguard osteoblasts from H2O2-induced damage by reducing intracellular reactive oxygen species (ROS). This protection resulted in enhanced cell survival and promoted osteoblast differentiation. This investigation underscores that DC can shield oxidative damage osteoblast model from oxidative stress, ameliorate osteoporosis, and enhance bone density in mice osteoporosis model. These findings suggest various DC applications in the food and medicine industries.

Leonurine Protects Bone Mesenchymal Stem Cells from Oxidative Stress by Activating Mitophagy through PI3K/Akt/mTOR Pathway

Osteoporosis bears an imbalance between bone formation and resorption, which is strongly related to oxidative stress. The function of leonurine on bone marrow-derived mesenchymal stem cells (BMSCs) under oxidative stress is still unclear. Therefore, this study was aimed at identifying the protective effect of leonurine on H₂O₂ stimulated rat BMSCs. We found that leonurine can alleviate cell apoptosis and promote the differentiation ability of rat BMSCs induced by oxidative stress at an appropriate concentration at 10 μM. Meanwhile, the intracellular ROS level and the level of the COX2 and NOX4 mRNA decreased after leonurine treatment in vitro. The ATP level and mitochondrial membrane potential were upregulated after leonurine treatment. The protein level of PINK1 and Parkin showed the same trend. The mitophage in rat BMSCs blocked by 3-MA was partially rescued by leonurine. Bioinformatics analysis and leonurine-protein coupling provides a strong direct combination between leonurine and the PI3K protein at the position of Asp841, Glu880, Val882. In conclusion, leonurine protects the proliferation and differentiation of BMSCs from oxidative stress by activating mitophagy, which depends on the PI3K/Akt/mTOR pathway. The results showed that leonurine may have potential usage in osteoporosis and bone defect repair in osteoporosis patients.

Additive Effect of Parathyroid Hormone and Zoledronate Acid on Prevention Particle Wears-Induced Implant Loosening by Promoting Periprosthetic Bone Architecture and Strength in an Ovariectomized Rat Model

Implant-generated particle wears are considered as the major cause for the induction of implant loosening, which is more susceptible to patients with osteoporosis. Monotherapy with parathyroid hormone (PTH) or zoledronate acid (ZOL) has been proven efficient for preventing early-stage periprosthetic osteolysis, while the combination therapy with PTH and ZOL has exerted beneficial effects on the treatment of posterior lumbar vertebral fusion and disuse osteopenia. However, PTH and ZOL still have not been licensed for the treatment of implant loosening to date clinically. In this study, we have explored the effect of single or combined administration with PTH and ZOL on implant loosening in a rat model of osteoporosis. After 12 weeks of ovariectomized surgery, a femoral particle-induced periprosthetic osteolysis model was established. Vehicle, PTH (5 days per week), ZOL (100 mg/kg per week), or combination therapy was utilized for another 6 weeks before sacrifice, followed by micro-CT, histology, mechanical testing, and bone turnover examination. PTH monotherapy or combined PTH with ZOL exerted a protective effect on maintaining implant stability by elevating periprosthetic bone mass and inhibiting pseudomembrane formation. Moreover, an additive effect was observed when combining PTH with ZOL, resulting in better fixation strength, higher periprosthetic bone mass, and less pseudomembrane than PTH monotherapy. Taken together, our results suggested that a combination therapy of PTH and ZOL might be a promising approach for the intervention of early-stage implant loosening in patients with osteoporosis.

The Effect of Daily Teriparatide versus One-Time Annually Zoledronic Acid Administration After Transforaminal Lumbar Interbody Fusion in Osteoporotic Patients

Purpose

The research aimed to compare the therapeutic effect of teriparatide (TPTD) and zoledronic acid (ZOL) therapy on bone formation and spinal fusion in patients with osteoporosis (OP) who underwent transforaminal lumbar interbody fusion (TLIF).

Methods

On the basis of different anti-OP treatment options, the TPTD group was treated daily with TPTD (20 μg. ih. qd) for at least 6 months, while the ZOL group was treated with a single dose of ZOL (5 mg. ivgtt. st) postoperatively. The visual analogue scale (VAS), Oswestry Disability Index (ODI), bone mineral density (BMD), and concentration of bone turnover markers before, 6, and 12 months after surgery were evaluated. X-ray and three-dimensional computed tomography scans were performed at 6 and 12 months postoperatively to assess interbody fusion.

Results

The number of patients in the TPTD and ZOL groups was 29 and 38 patients, respectively. The VAS and ODI scores in both groups were significantly reduced at 6 and 12 months after TLIF. Compared with that of baseline, the lumbar spine BMD of TPTD patients increased significantly from 0.716±0.137 g/cm² to 0.745±0.124 g/cm² and 0.795±0.123 g/cm² at 6 and 12 months, respectively, and was significantly higher than that of the ZOL group at 12 months (0.720±0.128 g/cm²). The bone formation marker, P1NP, in the TPTD group increased significantly (145.48±66.64 ng/mL and 119.55±88.27 ng/mL) compared with baseline (44.67±25.15 ng/mL) and in the ZOL group (28.82±19.76 ng/mL and 29.94±20.67 ng/mL) at 6 and 12 months, respectively. The fusion rates in the TPTD and ZOL groups were 57% and 45% at 6 months, without statistical significance. However, TPTD had a more statistically significant positive influence on fusion rate than ZOL at 12 months (86% vs 70%).

Conclusion

TPTD was more efficient than ZOL in bone formation and spinal fusion in OP patients who underwent TLIF.

Denosumab alleviates intervertebral disc degeneration adjacent to lumbar fusion by inhibiting endplate osteochondral remodeling and vertebral osteoporosis in ovariectomized rats

Background

Although adjacent segmental intervertebral disc degeneration (ASDD) is one of the most common complications after lumbar fusion, its exact mechanism remains unclear. As an antibody to RANKL, denosumab (Dmab) effectively reduces bone resorption and stimulates bone formation, which can increase bone mineral density (BMD) and improve osteoporosis. However, it has not been confirmed whether Dmab has a reversing or retarding effect on ASDD.

Methods

Three-month-old female Sprague-Dawley rats that underwent L4–L5 posterolateral lumbar fusion (PLF) with spinous-process wire fixation 4 weeks after bilateral ovariectomy (OVX) surgery were given Dmab 4 weeks after PLF surgery (OVX+PLF+Dmab group). In addition, the following control groups were defined: Sham, OVX, PLF, and OVX+PLF (n=12 each). Next, manual palpation and X-ray were used to evaluate the state of lumbar fusion. The bone microstructure in the lumbar vertebra and endplate as well as the disc height index (DHI) of L5/6 was evaluated by microcomputed tomography (μCT). The characteristic alterations of ASDD were identified via Safranin-O green staining. Osteoclasts were detected using tartrate-resistant acid phosphatase (TRAP) staining, and the biomechanical properties of vertebrae were evaluated. Aggrecan (Agg), metalloproteinase-13 (MMP-13), and a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS-4) expression in the intervertebral disc were detected by immunohistochemistry and real-time polymerase chain reaction (RT-PCR) analysis. In addition, the expression of CD24 and Sox-9 was assessed by immunohistochemistry.

Results

Manual palpation showed clear evidence of the fused segment’s immobility. Compared to the OVX+PLF group, more new bone formation was observed by X-ray examination in the OVX+PLF+Dmab group. Dmab significantly alleviated ASDD by retaining disc height index (DHI), decreasing endplate porosity, and increasing vertebral biomechanical properties and BMD. TRAP staining results showed a significantly decreased number of active osteoclasts after Dmab treatment, especially in subchondral bone and cartilaginous endplates. Moreover, the protein and mRNA expression results in discs (IVDs) showed that Dmab not only inhibited matrix degradation by decreasing MMP-13 and ADAMTS-4 but also promoted matrix synthesis by increasing Agg. Dmab maintained the number of notochord cells by increasing CD24 but reducing Sox-9.

Conclusions

These results suggest that Dmab may be a novel therapeutic target for ASDD treatment.

Anabolic agents: what is beyond osteoporosis?

Osteoporosis is a common skeletal disorder characterized by low bone mass, which leads to reduced bone strength and an increased risk of fractures. Anabolic agents have been shown to improve bone mass and decrease fracture risk in osteoporosis patients by directly stimulating osteoblasts to produce new bone. Currently, two anabolic agents are available in the USA: recombinantly produced teriparatide (TPTD), which is the fully active (1-34) amino active sequence of human parathyroid hormone (PTH), and abaloparatide (APTD), a synthetic analog of parathyroid hormone-related peptide (PTHrP). At present, both agents are approved only for treatment of patients with osteoporosis at high risk of fracture. Nonetheless, their anabolic properties have led to off-label application in additional settings which include spine fusion, osteonecrosis of the jaw, arthroplasty, and fracture healing. In this article, we summarize available scientific literature regarding the efficacy, effectiveness, and safety of TPTD in these off-label settings.

Medical optimization of lumbar fusion in the osteoporotic patient

PURPOSE

In patients undergoing lumbar fusion, osteoporosis has been shown to lead to poorer outcomes and greater incidence of fusion-related complications. Given the undesirable effect of osteoporosis on lumbar fusion surgery, a number of medications have been proposed for use in the peri- and postoperative period to mitigate risks and enhance outcomes. The purpose of this review was to summarize and synthesize the current literature regarding medical management of osteoporosis in the context of lumbar fusion surgery.

METHODS

A literature search of PubMed, Embase, and Web of Science was conducted in October 2016, using permutations of various search terms related to osteoporosis, medications, and lumbar fusion.

RESULTS

Teriparatide injections may lead to faster, more successful fusion, and may reduce fusion-related complications. Bisphosphonate therapy likely does not hinder fusion outcomes and may be useful in reducing certain complications of fusion in osteoporotic patients. Calcitonin and selective estrogen receptor modulator therapy show mixed results, but more research is necessary to make a recommendation. Vitamin D deficiency is associated with poor fusion outcomes, but evidence for supplementation in patients with normal serum levels is weak.

CONCLUSIONS

Overall, the current body of research appears to support the use of teriparatide therapy to enhance lumbar fusion outcomes in the osteoporotic patient, although the extent of research on this topic is limited. Additionally, very little evidence exists to cease any of the mentioned osteoporosis treatments prior to lumbar fusion.