Pulsed electromagnetic fields and platelet rich plasma alone and combined for the treatment of wear-mediated periprosthetic osteolysis: An in vivo study

The Effect of a Rotating Magnetic Field on the Regenerative Potential of Platelets

Platelets are actively involved in tissue injury site regeneration by producing a wide spectrum of platelet-derived growth factors such as PDGF (platelet-derived growth factor), IGF-1 (insulin-like growth factor), TGF-β1 (transforming growth factor β), FGF (fibroblast growth factor), etc. A rotating magnetic field (RMF) can regulate biological functions, including reduction or induction regarding inflammatory processes, cell differentiation, and gene expression, to determine the effect of an RMF on the regenerative potential of platelets. The study group consisted of 30 healthy female and male volunteers (n = 15), from which plasma was collected. A portion of the plasma was extracted and treated as an internal control group. Subsequent doses of plasma were exposed to RMF at different frequencies (25 and 50 Hz) for 1 and 3 h. Then, the concentrations of growth factors (IGF-1, PDGF-BB, TGF-β1, and FGF-1) were determined in the obtained material by the ELISA method. There were statistically significant differences in the PDGF-BB, TGF-β1, IGF-1, and FGF-1 concentrations between the analyzed groups. The highest concentration of PDGF-BB was observed in the samples placed in RMF for 1 h at 25 Hz. For TGF-β1, the highest concentrations were obtained in the samples exposed to RMF for 3 h at 25 Hz and 1 h at 50 Hz. The highest concentrations of IGF-1 and FGF-1 were shown in plasma placed in RMF for 3 h at 25 Hz. An RMF may increase the regenerative potential of platelets. It was noted that female platelets may respond more strongly to RMF than male platelets.

Inhibitory effects of Formononetin on CoCrMo particle-induced osteoclast activation and bone loss through downregulating NF-κB and MAPK signaling

Wear particle-induced osteoclast over-activation is a major contributor to periprosthetic osteolysis and aseptic loosening, which can cause pathological bone loss and destruction. Hence, inhibiting excessive osteoclast-resorbing activity is an important strategy for preventing periprosthetic osteolysis. Formononetin (FMN) has been shown to have protective effects against osteoporosis, but no previous study has evaluated the effects of FMN on wear particle-induced osteolysis. In this study, we found that FMN alleviated CoCrMo alloy particles (CoPs)-induced bone loss in vivo and inhibited the formation and bone-resorptive function of osteoclasts in vitro. Moreover, we revealed that FMN exerted inhibitory effects on the expression of osteoclast-specific genes via the classical NF-κB and MAPK signaling pathways in vitro. Collectively, FMN is a potential therapeutic agent for the prevention and treatment of periprosthetic osteolysis and other osteolytic bone diseases.

Harnessing electromagnetic fields to assist bone tissue engineering

Bone tissue engineering (BTE) emerged as one of the exceptional means for bone defects owing to it providing mechanical supports to guide bone tissue regeneration. Great advances have been made to facilitate the success of BTE in regenerating bone within defects. The use of externally applied fields has been regarded as an alternative strategy for BTE. Electromagnetic fields (EMFs), known as a simple and non-invasive therapy, can remotely provide electric and magnetic stimulation to cells and biomaterials, thus applying EMFs to assist BTE would be a promising strategy for bone regeneration. When combined with BTE, EMFs improve cell adhesion to the material surface by promoting protein adsorption. Additionally, EMFs have positive effects on mesenchymal stem cells and show capabilities of pro-angiogenesis and macrophage polarization manipulation. These advantages of EMFs indicate that it is perfectly suitable for representing the adjuvant treatment of BTE. We also summarize studies concerning combinations of EMFs and diverse biomaterial types. The strategy of combining EMFs and BTE receives encouraging outcomes and holds a promising future for effectively treating bone defects.

ROS-responsive hydrogel coating modified titanium promotes vascularization and osteointegration of bone defects by orchestrating immunomodulation

Ideal titanium implants are required to participate in bone repair actively to improve in situ osteointegration. However, the traditional surface functionalization methods of titanium implants are difficult to both achieve the active regulation and long-term stability of bioactive components. Here, a novel functionalized titanium which loaded with thymosin β4 (Tβ4) and covered by a hydrogel coating was designed and evaluated. A strong adhesion between the coating and the titanium substrate was realized by the synergistic action of borate ester bonds and surface topological structure. The hydrogel coating also achieved an in vivo adhesion between implant and tissue through hydrogen bonds and borate bonds. In addition, based on the ROS response property of borate bonds, the implant can release Tβ4 in response to the immune reaction of bone healing by regulating the polarization of macrophages, thereby reducing the fibrosis formation around the implant interface and promoting vascularization and osteointegration of bone defects.

Immunomodulatory strategies for bone regeneration: A review from the perspective of disease types

Tissue engineering strategies for treating bone loss to date have largely focused on targeting stem cells or vascularization. Immune cells, including macrophages and T cells, can also indirectly enhance bone healing via cytokine secretion to interact with other bone niche cells. Bone niche cues and local immune environment vary depending on anatomical location, size of defects and disease types. As such, it is critical to evaluate the role of the immune system in the context of specific bone niche and different disease types. This review focuses on immunomodulation research for bone applications using biomaterials and cell-based strategies, with a unique perspective from different disease types. We first reviewed applications for prolonging orthopaedic implant lifetime and enhancing fracture healing, two clinical challenges where immunomodulatory strategies were initially developed for orthopedic applications. We then reviewed recent research progress in harnessing immunomodulatory strategies for regenerating critical-sized, long bone or cranial bone defects, and treating osteolytic bone diseases. Remaining gaps in knowledge, future directions and opportunities were also discussed.

Combined Effects of Low-Frequency Pulsed Electromagnetic Field and Melatonin on Ovariectomy-Induced Bone Loss in Mice

Pulsed electromagnetic field (PEMF) therapy and melatonin (MEL) supplementation are expected to be important strategies for the treatment of osteoporosis. The aim of the current study was to investigate the efficacy of PEMF therapy, MEL supplementation, a combination of PEMF therapy, and MEL supplementation (PEMF + MEL) in mice with bilateral ovariectomy (OVX)-induced osteoporosis. Forty 12-week-old female C57/BL mice were randomly assigned to five groups (n = 8/group): OVX, PEMF, MEL, PEMF + MEL, and sham-operation (sham) groups. All mice in the first four groups were subjected to OVX. The mice in the PEMF and PEMF + MEL groups were exposed to PEMF (75 Hz, 1.6 mT, 1 h/day for 12 weeks), while those in the MEL and PEMF + MEL groups were administered MEL (50 mg/kg, i.p.). Body mass, micro-computed tomography, histology, immunohistochemistry, and real-time polymerase chain reaction were performed. PEMF + MEL treatment enhanced bone volume fraction (BV/TV) 2.2-fold over OVX control (P < 0.001) and increased expression levels of collagen type I (COL1) 1.9-fold and bone morphogenetic protein 2 (BMP2) 2.5-fold. PEMF + MEL also reduced the ratio of bone surface/bone volume (BS/BV) by 40% (P < 0.05) and appeared to reduce the number of osteoclasts in the metaphysis area. Preservation of bone value and bone microarchitecture in the combined therapy group were found to be superior to those in the single treatment groups. However, there were no apparent differences between the PEMF and MEL groups. The use of a combination of PEMF therapy and MEL supplementation may be an effective method to treat osteoporosis. © 2021 Bioelectromagnetics Society.

Platelet-Rich Plasma for Bone Fracture Treatment: A Systematic Review of Current Evidence in Preclinical and Clinical Studies

Background: Recently, there is an increasing interest in the therapeutic potential of platelet-rich plasma (PRP) for bone fracture treatment. Nevertheless, the effect of PRP for bone fracture treatment remains controversial and is still a matter of discussion. Therefore, we performed a systematic review to evaluate the efficacy and safety of PRP injection for treatment of bone fracture. Methods: The main bibliographic databases, including Medline, PubMed, Embase, Web of Science, and the Cochrane library, were comprehensively searched for studies focusing on the application of platelet-rich plasma (PRP) on bone fracture treatment. All relevant articles were screened for eligibility and subdivided into the preclinical and clinical studies. Data were extracted and presented systematically. Results: Finally, twenty-six in vitro preclinical studies (basic studies), nine in vivo preclinical studies (animal studies), and nine clinical studies, met the selection criteria, and were included in the present systematic review. Preclinical studies showed an overall positive effect of PRP on osteoblast-like cells in vitro and bone healing in animal models. The most used treatment for bone fracture in animal and clinical studies is fixation surgery combined with PRP injection. The clinical studies reported PRP shortened bony healing duration, and had no positive effect on improving the healing rate of closed fractures. However, the results of functional outcomes are controversial. Additionally, compared with control group, PRP would not increase the rate of postoperative wound infection. Conclusion: The present systematic review confirmed the continuing interests of PRP as an additional treatment for bone fracture. Preclinical studies highlighted the potential value of PRP as promising therapy for bone fracture. However, the preclinical evidence did not translate into a similar result in the clinical studies. In addition, types of fractures and procedures of PRP preparation are heterogeneous in enrolled studies, which might result in controversial results. Meanwhile, characteristics of PRP, such as platelet concentration, the numbers of leukocytes, still need to be determined and further research is required.

Effect of Oxidative Stress on Bone Remodeling in Periprosthetic Osteolysis

The success of implant performance and arthroplasty is based on several factors, including oxidative stress-induced osteolysis. Oxidative stress is a key factor of the inflammatory response. Implant biomaterials can release wear particles which may elicit adverse reactions in patients, such as local inflammatory response leading to tissue damage, which eventually results in loosening of the implant. Wear debris undergo phagocytosis by macrophages, inducing a low-grade chronic inflammation and reactive oxygen species (ROS) production. In addition, ROS can also be directly produced by prosthetic biomaterial oxidation. Overall, ROS amplify the inflammatory response and stimulate both RANKL-induced osteoclastogenesis and osteoblast apoptosis, resulting in bone resorption, leading to periprosthetic osteolysis. Therefore, a growing understanding of the mechanism of oxidative stress-induced periprosthetic osteolysis and anti-oxidant strategies of implant design as well as the addition of anti-oxidant agents will help to improve implants’ performances and therapeutic approaches.

Platelet-Rich Plasma Therapy in the Treatment of Diseases Associated with Orthopedic Injuries

Platelet-rich plasma (PRP) is an autologous platelet concentrate prepared from the whole blood that is activated to release growth factors (GFs) and cytokines and has been shown to have the potential capacity to reduce inflammation and improve tissue anabolism for regeneration. The use of PRP provides a potential for repair due to its abundant GFs and cytokines, which are key in initiating and modulating regenerative microenvironments for soft and hard tissues. Among outpatients, orthopedic injuries are common and include bone defects, ligament injury, enthesopathy, musculoskeletal injury, peripheral nerve injury, chronic nonhealing wounds, articular cartilage lesions, and osteoarthritis, which are caused by trauma, sport-related or other types of trauma, or tumor resection. Surgical intervention is often required to treat these injuries. However, for numerous reasons regarding limited regeneration capacity and insufficient blood supply of the defect region, these treatments commonly result in unsatisfactory outcomes, and follow-up treatment is challenging. The aim of the present review is to explore future research in the field of PRP therapy in the treatment of diseases associated with orthopedic injuries. Impact statement In recent years, platelet-rich plasma (PRP) has become widely used in the treatment of diseases associated with orthopedic injuries, and the results of numerous studies are encouraging. Due to diseases associated with orthopedic injuries being common in clinics, as a conservative treatment, more and more doctors and patients are more likely to accept PRP. Importantly, PRP is a biological product of autologous blood that is obtained by a centrifugation procedure to enrich platelets from whole blood, resulting in few complications, such as negligible immunogenicity from an autologous source, and it is also simple to produce through an efficient and cost-effective method in a sterile environment. However, the applicability, advantages, and disadvantages of PRP therapy have not yet been fully elucidated. The aim of the present review is to explore future research in the field of PRP therapy in the treatment of diseases associated with orthopedic injuries, as well as to provide references for clinics.

Puerarin inhibits titanium particle-induced osteolysis and RANKL-induced osteoclastogenesis via suppression of the NF-κB signaling pathway

Osteolysis around the prosthesis and subsequent aseptic loosening are the main causes of prosthesis failure. Inflammation due to wear particles and osteoclast activation are the key factors in osteolysis and are also potential targets for the treatment of osteolysis. However, it is not clear whether puerarin can inhibit chronic inflammation and alleviate osteolysis. In this study, we investigated the effect of puerarin on Ti particle-induced inflammatory osteolysis in vivo in rat femoral models and in vitro in receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclast activation models. Our in vivo results showed that puerarin significantly inhibited Ti particle-induced osteolysis and the expression of matrix metallopeptidase 9 (MMP-9), nuclear factor of activated T cells 1 (NFATc1), tumour necrosis factor (TNF)-α and interleukin (IL)-6. In vitro, puerarin prevented RANKL-induced osteoclast differentiation, bone resorption and F-actin ring formation in a concentration-dependent manner. Furthermore, puerarin decreased the phosphorylation of p65 and prevented p65 moving from the cytoplasm to the nucleus. Puerarin also reduced the expression of osteoclast-specific factors and inhibited the inflammatory response. In conclusion, our study proves that puerarin can block the NF-κB signalling pathway to inhibit osteoclast activation and inflammatory processes, which provides a new direction for the treatment of osteolysis-related diseases.

Punicalagin ameliorates wear-particle-induced inflammatory bone destruction by bi-directional regulation of osteoblastic formation and osteoclastic resorption

Periprosthetic osteolysis (PPO) and subsequent aseptic loosening are the main causes of implant failure and revision surgery. Emerging evidence has suggested that wear-particle-induced chronic inflammation, osteoblast inhibition and osteoclast formation at the biointerface of implant materials are responsible for PPO. Punicalagin (PCG), a polyphenolic compound molecularly extracted from pomegranate rinds, plays a critical role in antioxidant, anticancer and anti-inflammatory activities. However, whether PCG could attenuate chronic inflammation and bone destruction at sites of titanium (Ti)-particle-induced osteolysis remains to be determined. In this study, we explored the effect of PCG on Ti-particle-induced osteolysis in vivo and osteoblast and osteoclast differentiation in vitro. We found that PCG could relieve wear-particle-induced bone destruction in a murine calvarial osteolysis model by increasing bone formation activity and suppressing bone resorption activity. PCG treatment also reduced the Ti-particle-induced inflammatory response in vivo and vitro. In addition, we also observed that PCG promotes osteogenic differentiation of MC3T3-E1 cells under inflammatory conditions and inhibits RANKL-induced osteoclast formation of bone marrow-derived macrophages (BMMs). Meanwhile, the induction of the RANKL to OPG ratio was reversed by PCG treatment in vivo and in vitro, which demonstrated that PCG could also indirectly inhibit osteoclastogenesis. Collectively, our findings suggest that PCG represents a potential approach for the treatment of wear-particle-induced inflammatory osteolysis.

Bone regenerative medicine: metatarsus defects in sheep to evaluate new therapeutic strategies for human long bone defect. A systematic review

INTRODUCTION

Large bone defects in long bone are not able to repair themselves and require grafts. Although autograft is the gold standard, it is associated with some disadvantages. Consequently, the application of tissue engineering (TE) techniques help with the use of allogenic biological and artificial scaffolds, cells and growth factors (GFs). Following 3Rs and in vitro testing strategies, animal models are required in preclinical in vivo studies to evaluate the therapeutic effects of the most promising TE techniques.

MATERIALS AND METHODS

A systematic review was performed from 2000 to 2019 to evaluate bone regeneration sheep metatarsus defects.

RESULTS

Eleven in vivo studies on sheep metatarsus defect were retrieved. The mid-diaphysis of metatarsus was the region most employed to perform critical size defects. Natural, synthetic and hybrid scaffolds were implanted, combined with bone marrow mesenchymal stem cells (BMSCs), GFs such as osteogenic protein 1 (OP1) and platelet rich plasma (PRP). The maximum follow-up period was 4 and 6 months in which radiography, histology, histomorphometry, computed tomography (CT) and biomechanics were performed to evaluate the healing status.

CONCLUSIONS

the sheep metatarsus defect model seems to be a suitable environment with a good marriage of biological and biomechanical properties. Defects of 3 cm are treated with natural scaffolds (homologous graft or allografts), those of 2.5 cm with natural, synthetic or composite scaffolds, while little defects (0.5 × 0.5 cm) with composite scaffolds. No difference in results is found regardless of the defect size.

Role of pulsed electromagnetic fields after joint replacements

Although the rate of patients reporting satisfaction is generally high after joint replacement surgery, up to 23% after total hip replacement and 34% after total knee arthroplasty of treated subjects report discomfort or pain 1 year after surgery. Moreover, chronic or subacute inflammation is reported in some cases even a long time after surgery. Another open and debated issue in prosthetic surgery is implant survivorship, especially when related to good prosthesis bone ingrowth. Pulsed Electro Magnetic Fields (PEMFs) treatment, although initially recommended after total joint replacement to promote bone ingrowth and to reduce inflammation and pain, is not currently part of usual clinical practice. The purpose of this review was to analyze existing literature on PEMFs effects in joint replacement surgery and to report results of clinical studies and current indications. We selected all currently available prospective studies or RCT on the use of PEMFs in total joint replacement with the purpose of investigating effects of PEMFs on recovery, pain relief and patients’ satisfaction following hip, knee or shoulder arthroplasty. All the studies analyzed reported no adverse effects, and good patient compliance to the treatment. The available literature shows that early control of joint inflammation process in the first days after surgery through the use of PEMFs should be considered an effective completion of the surgical procedure to improve the patient’s functional recovery.

Early changes in serum osteocalcin and body weight are predictive of implant fixation in a rat model of implant loosening

Biomarkers are of interest to identify patients at risk for peri-implant osteolysis and aseptic loosening. We used a rat model of particle-induced peri-implant osteolysis to investigate if early changes in biomarkers were associated with subsequent implant fixation strength. Implants were placed in rat femora, which were then challenged with intra-articular knee injections of either clean polyethylene, lipopolysaccharide-doped polyethylene, or cobalt-chromium alloy particles, with particle-free vehicle serving as control (n ≥ 8 per group). Rats were weighed weekly, blood was collected at weeks 0, 3, 5, and 6, and locomotor behavior was assessed 4 days before study conclusion. Rats were euthanized 6 weeks post surgery. Week 6 serum was analyzed for five bone remodeling markers, while longitudinal serum was assessed for osteocalcin. Bone-implant contact, peri-implant trabecular architecture, and implant fixation strength were measured. Rats challenged with cobalt-chromium particles had a significant reduction in implant fixation strength compared with the vehicle-control group (P = .034). This group also had elevated serum osteocalcin (P = .005), depressed weight gain (P = .001) and less frequent rearing behavior (P = .029). Regardless of group, change in serum osteocalcin at week 3 (r = -.368; P = .046), change in weight at week 2 (r = .586; P < .001), as well as weight change at all other time intervals were associated with fixation strength. The finding that early alterations in serum osteocalcin and body weight were predictive of subsequent implant fixation strength supports continued investigation of biomarkers for early detection of peri-implant osteolysis and implant loosening. Further, change in biomarker levels was found to be more indicative of implant fixation status than any single measurement.

Histological, Histomorphometrical, and Biomechanical Studies of Bone-Implanted Medical Devices: Hard Resin Embedding

The growing incidence of degenerative musculoskeletal disorders as well as lifestyle changes has led to an increase in the surgical procedures involving implanted medical devices in orthopedics. When studying implant/tissue interface in hard materials (i.e., metals or dense plastics) and/or in large bone segments, the hard plastic embedding of the intact undecalcified tissue envelope with the implant in situ is needed. The aim of this work is to describe the advances and the possibilities of high-temperature methyl methacrylate (MMA) embedding for the histological, histomorphometrical, and biomechanical assessment of bone-implanted medical devices. Unlike routine techniques, undecalcified bone processing histology, using high-temperature MMA, requires a complex and precise sample processing methodology and the availability of sophisticated equipment and software for both sample preparation and analyses. MMA embedding permits the evaluation of biological responses to the presence of implanted medical devices without implant removal, allowing simultaneous qualitative and quantitative histological evaluation, both static and dynamic histomorphometry, and biomechanical analyses not possible with tissue decalcification. MMA embedding, despite being a demanding procedure, is still preferred to other kinds of resin-based embedding because of its peculiar characteristics, which allow the study of samples of big dimensions also implanted with hard materials without reducing the sample or removing the material. Dynamic measurements are allowed together with biomechanical investigations at the bone-biomaterial interface, obtaining a comprehensive and precise evaluation of the safety and effectiveness of medical devices for orthopedic regenerative, reconstructive, and reparative surgery.

Insight into Mechanobiology: How Stem Cells Feel Mechanical Forces and Orchestrate Biological Functions

The cross-talk between stem cells and their microenvironment has been shown to have a direct impact on stem cells' decisions about proliferation, growth, migration, and differentiation. It is well known that stem cells, tissues, organs, and whole organisms change their internal architecture and composition in response to external physical stimuli, thanks to cells' ability to sense mechanical signals and elicit selected biological functions. Likewise, stem cells play an active role in governing the composition and the architecture of their microenvironment. Is now being documented that, thanks to this dynamic relationship, stemness identity and stem cell functions are maintained. In this work, we review the current knowledge in mechanobiology on stem cells. We start with the description of theoretical basis of mechanobiology, continue with the effects of mechanical cues on stem cells, development, pathology, and regenerative medicine, and emphasize the contribution in the field of the development of ex-vivo mechanobiology modelling and computational tools, which allow for evaluating the role of forces on stem cell biology.

Biophysical stimulation of bone and cartilage: state of the art and future perspectives

INTRODUCTION

Biophysical stimulation is a non-invasive therapy used in orthopaedic practice to increase and enhance reparative and anabolic activities of tissue.

METHODS

A sistematic web-based search for papers was conducted using the following titles: (1) pulsed electromagnetic field (PEMF), capacitively coupled electrical field (CCEF), low intensity pulsed ultrasound system (LIPUS) and biophysical stimulation; (2) bone cells, bone tissue, fracture, non-union, prosthesis and vertebral fracture; and (3) chondrocyte, synoviocytes, joint chondroprotection, arthroscopy and knee arthroplasty.

RESULTS

Pre-clinical studies have shown that the site of interaction of biophysical stimuli is the cell membrane. Its effect on bone tissue is to increase proliferation, synthesis and release of growth factors. On articular cells, it creates a strong A_2A and A₃ adenosine-agonist effect inducing an anti-inflammatory and chondroprotective result. In treated animals, it has been shown that the mineralisation rate of newly formed bone is almost doubled, the progression of the osteoarthritic cartilage degeneration is inhibited and quality of cartilage is preserved. Biophysical stimulation has been used in the clinical setting to promote the healing of fractures and non-unions. It has been successfully used on joint pathologies for its beneficial effect on improving function in early OA and after knee surgery to limit the inflammation of periarticular tissues.

DISCUSSION

The pooled result of the studies in this review revealed the efficacy of biophysical stimulation for bone healing and joint chondroprotection based on proven methodological quality.

CONCLUSION

The orthopaedic community has played a central role in the development and understanding of the importance of the physical stimuli. Biophysical stimulation requires care and precision in use if it is to ensure the success expected of it by physicians and patients.