Curcumin Promotes Femoral Fracture Healing in a Rat Model by Activation of Autophagy

3-MA attenuates collagen-induced arthritis in vivo via anti-inflammatory effect and autophagy inhibition

BACKGROUND

Rheumatoid arthritis (RA) is a chronic autoimmune disease which afflicts about nearly 1% of global population. RA results in synovitis and cartilage/bone damage, even disability which aggravates the health burden. Many drugs are used to relieve RA, such as glucocorticoids (GCs), non-steroidal anti-inflammatory drugs (NSAIDs), and disease-modifying anti-rheumatic drugs (DMARDs) in the clinical treatment. However, present clinical drugs have various disadvantages such as poor bioavailability and short biological half-life and drug resistance, or adverse effects. A recent study showed autophagy modulation may be a novel strategy in the treatment of RA. 3-Methylademine (3-MA), is the most widely used autophagy inhibitor, which blocks autophagy at the initiation and maturation stages. The aim of this study is to evaluate the effect of 3-MA in collagen-induced-arthritis (CIA) mice and further elucidate how 3-MA attenuated inflammation, and cartilage/bone damage in arthritis.

METHODS

An in-vivo mouse collagen-induced arthritis model was applied to compare differences in ankle destruction among control mice and CIA mice treated with or without 3-MA. Bone and cartilage destruction degree was evaluated by histology and micro-computed tomography (µCT). Further in-vivo assays utilized mouse serum samples to investigate inflammatory levels, oxidative levels, and bone resorption cytokines. At last, an immunofluorescence assay was applied to detect the autophagy level among the three groups.

RESULTS

The in-vivo mouse collagen-induced arthritis model showed that CIA mice revealed apparent hind paw and ankle swelling which was aggravated gradually along with time, while 3-MA treatment attenuated swelling gradually. µCT and histological results showed typical lesions in CIA group while 3-MA treatment alleviated arthritis-related destruction. Serum assay showed that 3-MA significantly reduced inflammatory cytokines levels, suppressed oxidative levels and bone resorption cytokines. Immunofluorescence assay revealed 3-MA significantly inhibited the abnormal autophagy level in CIA mouse ankle.

CONCLUSIONS

3-MA protects bone destruction in CIA-induced mice arthritis by anti-inflammatory effect and autophagy inhibition.

Effect of Curcumin-containing Nanofibrous Gelatin-hydroxyapatite Scaffold on Proliferation and Early Osteogenic Differentiation of Dental Pulp Stem Cells

BACKGROUND

In recent years, the electrospinning method has received attention because of its usage in producing a mimetic nanocomposite scaffold for tissue regeneration. Hydroxyapatite and gelatin are suitable materials for producing scaffolds, and curcumin has the osteogenesis induction effect.

AIMS

This study aimed to evaluate the toxicity and early osteogenic differentiation stimulation of nanofibrous gelatin-hydroxyapatite scaffold containing curcumin on dental pulp stem cells (DPSCs).

OBJECTIVE

The objective of the present investigation was the evaluation of the proliferative effect and primary osteogenic stimulation of DPSCs with a nanofibrous gelatin-hydroxyapatite scaffold containing curcumin. Hydroxyapatite and gelatin were used as suitable and biocompatible materials to make a scaffold suitable for stimulating osteogenesis. Curcumin was added to the scaffold as an osteogenic differentiation- enhancing agent.

METHODS

The effect of nano-scaffold on the proliferation of DPSCs was evaluated. The activity of alkaline phosphatase (ALP) as the early osteogenic marker was considered to assess primary osteogenesis stimulation in DPSCs.

RESULTS

The nanofibrous gelatin-hydroxyapatite scaffold containing curcumin significantly increased the proliferation and the ALP activity of DPSCs (P<0.05). The proliferative effect was insignificant in the first 2 days, but the scaffold increased cell proliferation by more than 40% in the fourth and sixth days. The prepared scaffold increased the activity of the ALP of DPSCs by 60% compared with the control after 14 days (p<0.05).

CONCLUSION

The produced nanofibrous gelatin-hydroxyapatite scaffold containing curcumin can be utilized as a potential candidate in tissue engineering and regeneration of bone and tooth.

FUTURE PROSPECTS

The prepared scaffold in the present study could be a beneficial biomaterial for tissue engineering and the regeneration of bone and tooth soon.

Autophagy: An important target for natural products in the treatment of bone metabolic diseases

Bone homeostasis depends on a precise dynamic balance between bone resorption and bone formation, involving a series of complex and highly regulated steps. Any imbalance in this process can cause disturbances in bone metabolism and lead to the development of many associated bone diseases. Autophagy, one of the fundamental pathways for the degradation and recycling of proteins and organelles, is a fundamental process that regulates cellular and organismal homeostasis. Importantly, basic levels of autophagy are present in all types of bone-associated cells. Due to the cyclic nature of autophagy and the ongoing bone metabolism processes, autophagy is considered a new participant in bone maintenance. Novel therapeutic targets have emerged as a result of new mechanisms, and bone metabolism can be controlled by interfering with autophagy by focusing on certain regulatory molecules in autophagy. In parallel, several studies have reported that various natural products exhibit a good potential to mediate autophagy for the treatment of metabolic bone diseases. Therefore, we briefly described the process of autophagy, emphasizing its function in different cell types involved in bone development and metabolism (including bone marrow mesenchymal stem cells, osteoblasts, osteocytes, chondrocytes, and osteoclasts), and also summarized research advances in natural product-mediated autophagy for the treatment of metabolic bone disease caused by dysfunction of these cells (including osteoporosis, rheumatoid joints, osteoarthritis, fracture nonunion/delayed union). The objective of the study was to identify the function that autophagy serves in metabolic bone disease and the effects, potential, and challenges of natural products for the treatment of these diseases by targeting autophagy.

Aspirin effect on bone remodeling and skeletal regeneration: Review article

Bone tissues are one of the most complex tissues in the body that regenerate and repair themselves spontaneously under the right physiological conditions. Within the limitations of treating bone defects, mimicking tissue engineering through the recruitment of scaffolds, cell sources and growth factors, is strongly recommended. Aspirin is one of the non-steroidal anti-inflammatory drugs (NSAIDs) and has been used in clinical studies for many years due to its anti-coagulant effect. On the other hand, aspirin and other NSAIDs activate cytokines and some mediators in osteoclasts, osteoblasts and their progenitor cells in a defect area, thereby promoting bone regeneration. It also stimulates angiogenesis by increasing migration of endothelial cells and the newly developed vessels are of emergency in bone fracture repair. This review covers the role of aspirin in bone tissue engineering and also, highlights its chemical reactions, mechanisms, dosages, anti-microbial and angiogenesis activities.

Mechanisms of autophagy and mitophagy in skeletal development, diseases and therapeutics

Autophagy is a highly evolutionarily conserved process in the eukaryotic cellular system by which dysfunctional organelles are selectively degraded through a series of processes of lysosomal activity and then returned to the cytoplasm for reuse. All cells require this process to maintain cellular homeostasis and promote cell survival during stress responses such as deprivation and hypoxia. Osteoblasts and osteoclasts are two cellular phenotypes in the bone that mediate bone homeostasis. However, an imbalance between osteoblastic bone formation and osteoclastic bone resorption contributes to the onset of bone diseases. Recent studies suggest that autophagy, mitophagy, and selective mitochondrial autophagy may play an essential role in regulating osteoblast differentiation and osteoclast maturation. Autophagic activity dysregulation alters the equilibrium between osteoblastic bone creation and osteoclastic bone resorption, allowing bone disorders like osteoporosis to develop more easily. The current review emphasizes the role of autophagy and mitophagy and their related molecular mechanisms in bone metabolic disorders. In the current review, we emphasize the role of autophagy and mitophagy as well as their related molecular mechanism in bone metabolic disorders. Furthermore, we will discuss autophagy as a target for the treatment of metabolic bone disease and future application in therapeutic translational research.

Effect of turmeric extract on bone healing in an experimental model of femoral bone fracture

Objective

Following bone trauma, several factors participate in making a balance between the activity of osteoblasts and osteoclasts. The receptor activator of nuclear factor kappa B ligand (RANKL), receptor activator of nuclear factor kappa B (RANK), and osteoprotegerin (OPG) molecules play critical roles in the healing process via regulation of osteoclasts function. Turmeric is suggested to have an anti-osteogenic potential; however, its effect on accelerating bone healing has not been adequately studied. Here, we used a rat model of femur fracture to explore the effect of treatment with turmeric extract on the bone repair and the expression of RANK, RANKL, and OPG molecules.

Materials and Methods

Eight rats were subjected to surgery, randomly divided into two groups, and treated orally with turmeric (200 mg/kg), or olive oil. Four oil-treated rats without bone fracture were used as control group. After six weeks of treatment, the femurs of animals were examined for radiological, histological, and gene expression analysis.

Results

X-ray radiography showed thicker callus and a more obscure fracture line in the turmeric group. Furthermore, higher osteoblast percentages but no osteoclasts were observed in turmeric-treated animals, representing better repair of bone in the fracture site. Also, real-time analyses showed that treatment with turmeric reduced RANK and RANKL expression (p<0.0001) and lowered RANKL/OPG ratio (p=0.01) in femoral bone tissue.

Conclusion

Our findings indicated the turmeric ability to facilitate bone hemostasis and optimize the expression of key markers involved in the bone metabolism.

Regulation of osteoblast autophagy based on PI3K/AKT/mTOR signaling pathway study on the effect of β-ecdysterone on fracture healing

Objectives

To investigate the effects of β-ecdysterone on fracture healing and the underlying mechanism.

Methods

MTT assay was used to detect the cell viability. AO/PI and flow cytometry assays were used to determine the apoptotic rate. The expression level of RunX2, ATG7 and LC3 was evaluated by qRT-PCR and Western blot assays. X-ray and HE staining were conducted on the fractured femur. Immunohistochemical assay was used to detect the expression level of Beclin-1 and immunofluorescence assay was used to measure the expression level of LC3 in the fractured femurs. Western blot was utilized to determine the expression level of PI3K, p-AKT1, AKT1, p-mTOR, mTOR, p-p70S6K, and p70S6K.

Results

The ALP activity and the expression of RunX2 in fractured osteoblasts were significantly elevated, the apoptotic rate was suppressed by rapamycin, 60, and 80 μM β-ecdysterone. The state of autophagy both in fractured osteoblasts and femurs was facilitated by rapamycin and β-ecdysterone. Compared to control, Garrett score was significantly promoted in rapamycin and β-ecdysterone groups, accompanied by ameliorated pathological state. Lastly, the PI3K/AKT/mTOR pathway both in fractured osteoblasts and femurs was inhibited by rapamycin and β-ecdysterone.

Conclusion

β-ecdysterone might facilitate fracture healing by activating autophagy through suppressing PI3K/AKT/mTOR signal pathway.

Nanofibrous asymmetric collagen/curcumin membrane containing aspirin-loaded PLGA nanoparticles for guided bone regeneration

The goal of the current study was to develop an asymmetric guided bone regeneration (GBR) membrane benefiting from curcumin and aspirin. The membrane was prepared using electrospinning technique and then was physic-chemically characterized by the conventional methods. The release profile of aspirin from the prepared membrane was also measured by ultraviolet spectrophotometry. Also, the antibacterial activities of the membrane was evaluated. We also assessed the in vitro effects of the prepared membrane on the biocompatibility and osteogenic differentiation of dental pulp stem cells (DPSCs), and evaluated in vivo bone regeneration using the prepared membrane in the defects created in both sides of the dog’s jaw by histology. The results from the characterization specified that the membrane was successfully prepared with monodispersed nanosized fibers, uniform network shaped morphology, negative surface charge and sustained release platform for aspirin. The membrane also showed antimicrobial effects against all tested bacteria. The presence of curcumin and aspirin in the asymmetric membrane enhanced osteogenic potential at both transcriptional and translational levels. The results of the animal test showed that the test area was completely filled with new bone after just 28 days, while the commercial membrane area remained empty. There was also a soft tissue layer above the new bone area in the test side. We suggested that the prepared membrane in this work could be used as a GBR membrane to keep soft tissue from occupying bone defects in GBR surgeries. Besides, the surgeries can be benefited from antibacterial activities and bone healing effects of this novel GBR membrane while, simultaneously, promoting bone regeneration.

Advances and Promises of Nutritional Influences on Natural Bone Repair

Impaired fracture healing continues to be a significant public health issue. This is more frequently observed in aging populations and patients with co-morbidities that can directly influence bone repair. Tremendous progress has been made in the development of biologics to enhance and accelerate the healing process; however, side-effects persist that can cause significant discomfort and tissue damage. This has been the impetus for the development of safe and natural strategies to hasten natural bone healing. Of the many possible approaches, nutrition represents a safe, affordable, and non-invasive strategy to positively influence each phase of fracture repair. However, our understanding of how healing can be hindered by malnutrition or enhanced with nutritional supplementation has lagged behind the advancements in both surgical management and the knowledge of molecular and cellular drivers of skeletal fracture repair. This review serves to bridge this knowledge gap as well as define the importance of nutrition during fracture healing. The extant literature clearly indicates that pre-existing nutritional deficiencies should be corrected, and nutritional status should be carefully monitored to prevent the development of malnutrition for the best possible healing outcome. It remains unclear, however, whether the provision of nutrients beyond sufficiency has any benefit on fracture repair and patient outcomes. The combined body of pre-clinical studies using a variety of animal models suggests a promising role of nutrition as an adjuvant therapy to facilitate fracture repair, but extensive research is needed, specifically at the clinical level, to clarify the utility of nutritional interventions in orthopedics. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:695-707, 2020.

Effect of curcumin on bone healing: An experimental study in a rat model of femur fracture

OBJECTIVE

To determine the radiologic, histologic and biomechanical effects of curcumin on bone healing using a total rat femur fracture injury model.

MATERIALS AND METHODS

Sixty four male Wistar-Albino rats weighing 170-210 g were used in this study. The animals were randomly divided into eight groups and 5 or 6 animals were placed in each cage. A transverse femur shaft fracture model used. The animals in study groups received oral curcumin at a dose of 200 mg/kg for 14 days or 28 days. Remaining animals received only saline solution by oral gavage for a period of 14 days and 28 days as control groups. After sacrification the left femurs used for radiological, histological and biomechanical evaluation.

RESULTS

The groups treated with curcumin showed no significant difference in terms of radiological, histological and biomechanical evaluations in 14 days groups. Also there was no significant difference between curcumin and control groups for 28 days according to radiological, histological and biomechanical tests.

CONCLUSIONS

According to our results, curcumin has no positive effect on fracture healing not only histologically but also radiologically and biomechanically. Curcumin's antioxidant effect may be more noticeable with long term follow up investigation as it may have a positive effect in remodelling phase. Long term follow up designed studies may be planned to investigate its effect on remodelling phase of fracture healing.

Role of Autophagy on Heavy Metal-Induced Renal Damage and the Protective Effects of Curcumin in Autophagy and Kidney Preservation

Curcumin is a hydrophobic polyphenol compound extracted from the rhizome of turmeric. The protective effect of curcumin on kidney damage in multiple experimental models has been widely described. Its protective effect is mainly associated with its antioxidant and anti-inflammatory properties, as well as with mitochondrial function maintenance. On the other hand, occupational or environmental exposure to heavy metals is a serious public health problem. For a long time, heavy metals-induced nephrotoxicity was mainly associated with reactive oxygen species overproduction and loss of endogenous antioxidant activity. However, recent studies have shown that in addition to oxidative stress, heavy metals also suppress the autophagy flux, enhancing cell damage. Thus, natural compounds with the ability to modulate and restore autophagy flux represent a promising new therapeutic strategy. Furthermore, it has been reported in other renal damage models that curcumin’s nephroprotective effects are related to its ability to regulate autophagic flow. The data indicate that curcumin modulates autophagy by classic signaling pathways (suppression of protein kinase B (Akt)/mammalian target of rapamycin (mTOR) and/or by stimulation of adenosine monophosphate-activated protein kinase (AMPK) and extracellular signal-dependent kinase (ERK) pathways). Moreover, it allows lysosomal function preservation, which is crucial for the later stage of autophagy. However, future studies of autophagy modulation by curcumin in heavy metals-induced autophagy flux impairment are still needed.

GIT1 contributes to autophagy in osteoclast through disruption of the binding of Beclin1 and Bcl2 under starvation condition

Approximately 10–15% of all bone fractures do not heal properly, causing patient morbidity and additional medical care expenses. Therefore, better mechanism-based fracture repair approaches are needed. In this study, a reduced number of osteoclasts (OCs) and autophagosomes/autolysosomes in OC can be observed in GPCR kinase 2-interacting protein 1 (GIT1) knockout (KO) mice on days 21 and 28 post-fracture, compared with GIT1 wild-type (GIT1 WT) mice. Furthermore, in vitro experiments revealed that GIT1 contributes to OC autophagy under starvation conditions. Mechanistically, GIT1 interacted with Beclin1 and promoted Beclin1 phosphorylation at Thr119, which induced the disruption of Beclin1 and Bcl2 binding under starvation conditions, thereby, positively regulating autophagy. Taken together, the findings suggest a previously unappreciated role of GIT1 in autophagy of OCs during fracture repair. Targeting GIT1 may be a potential therapeutic approach for bone fractures.