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Cellular reprogramming technologies have been developed with different physicochemical factors to improve the reprogramming efficiencies of induced pluripotent stem cells (iPSCs). Ultrasound is a clinically applied noncontact biophysical factor known for regulating various cellular behaviors but remains uninvestigated for cellular reprogramming. Here, we present a new reprogramming strategy using low-intensity ultrasound (LIUS) to improve cellular reprogramming of iPSCs in vitro and in vivo. Under 3D microenvironment conditions, increased LIUS stimulation shows enhanced cellular reprogramming of the iPSCs. The cellular reprogramming process facilitated by LIUS is accompanied by increased mesenchymal to epithelial transition and histone modification. LIUS stimulation transiently modulates the cytoskeletal rearrangement, along with increased membrane fluidity and mobility to increase HA/CD44 interactions. Furthermore, LIUS stimulation with HA hydrogel can be utilized in application of both human cells and in vivo environment, for enhanced reprogrammed cells into iPSCs. Thus, LIUS stimulation with a combinatorial 3D microenvironment system can improve cellular reprogramming in vitro and in vivo environments, which can be applied in various biomedical fields.

During physical activities, chondrocytes experience coupled stimulation of hydrostatic pressure (HP) and a transient increase in temperature (T), with the latter varying within a physiological range from 32.5 °C to 38.7 °C. Previous short-term in vitro studies have demonstrated that the combined hydrostatic pressure-thermal (HP-T) stimuli more significantly enhance chondroinduction and chondroprotection of chondrocytes than isolated applications. Interestingly, this combined benefit is associated with a corresponding increase in HSP70 levels when HP and T are combined. The current study therefore explored the indispensable role of HSP70 in mediating the combined effects of HP-T stimuli on chondrocytes. In this mid-long-term study of in vitro engineered cartilage constructs, we assessed chondrocyte responses to HP-T stimuli using customized bioreactor in standard and HSP70-inhibited cultures. Surprisingly, under HSP70-inhibited conditions, the usually beneficial HP-T stimuli, especially its thermal component, exerted detrimental effects on chondrocyte homeostasis, showing a distinct and unfavorable shift in gene and protein expression patterns compared to non-HSP70-inhibited settings. Such effects were corroborated through mechanical testing and confirmed using a secondary cell source. A proteomic-based mechanistic analysis revealed a disruption in the balance between biosynthesis and fundamental cellular structural components in HSP70-inhibited conditions under HP-T stimuli. Our results highlight the critical role of sufficient HSP70 induction in mediating the beneficial effects of coupled HP-T stimulation on chondrocytes. These findings help pave the way for new therapeutic approaches to enhance physiotherapy outcomes and potentially shed light on the elusive mechanisms underlying the onset of cartilage degeneration, a long-standing enigma in orthopedics. [ABSTRACT FROM AUTHOR]

Nerve regeneration following traumas remains an unmet challenge. The application of pulsed electromagnetic field (PEMF) stimulation has gained traction for a minimally invasive regeneration of nerves. However, a systematic exploration of different PEMF parameters influencing neuron function at a cellular level is not available. In this study, we exposed neuroblastoma F11 cells to PEMF to trigger beneficial effects on neurite outgrowth. Different carrier frequencies, pulse repetition frequencies, and duty cycles were screened with a custom ad hoc setup to find the most influential parameters values. A carrier frequency of 13.5 MHz, a pulse repetition frequency of 20 Hz, and a duty cycle of 10% allowed maximal neurite outgrowth, with unaltered viability with respect to non-stimulated controls. Furthermore, in a longer-term analysis, such optimal conditions were also able to increase the gene expression of neuronal expression markers NeuN and Tuj-1 and transcription factor Ngn1. Finally, the same optimal stimulation conditions were also applied to THP-1 macrophages, and both pro-inflammatory (TNF-α, IL-1β, IL-6, IL-8) and anti-inflammatory cytokines (IL-10, CD206) were analyzed. The optimal PEMF stimulation parameters did not induce differentiation towards an M1 macrophage phenotype, decreased IL-1β and IL-8 gene expression, decreased TNF-α and IL-8 cytokine release in M1-differentiated cells, increased IL-10 and CD206 gene expression, as well as IL-10 cytokine release in M0 cells. The specific PEMF stimulation regime, which is optimal in vitro, might have a high potential for a future in vivo translation targeting neural regeneration and anti-inflammatory action for treating peripheral nerve injuries.

Nerve regeneration following traumas remains an unmet challenge. The application of pulsed electromagnetic field (PEMF) stimulation has gained traction for a minimally invasive regeneration of nerves. However, a systematic exploration of different PEMF parameters influencing neuron function at a cellular level is not available. In this study, we exposed neuroblastoma F11 cells to PEMF to trigger beneficial effects on neurite outgrowth. Different carrier frequencies, pulse repetition frequencies, and duty cycles were screened with a custom ad hoc setup to find the most influential parameters values. A carrier frequency of 13.5 MHz, a pulse repetition frequency of 20 Hz, and a duty cycle of 10% allowed maximal neurite outgrowth, with unaltered viability with respect to non-stimulated controls. Furthermore, in a longer-term analysis, such optimal conditions were also able to increase the gene expression of neuronal expression markers NeuN and Tuj-1 and transcription factor Ngn1. Finally, the same optimal stimulation conditions were also applied to THP-1 macrophages, and both pro-inflammatory (TNF-α, IL-1 β, IL-6, IL-8) and anti-inflammatory cytokines (IL-10, CD206) were analyzed. The optimal PEMF stimulation parameters did not induce differentiation towards an M1 macrophage phenotype, decreased IL-1 β and IL-8 gene expression, decreased TNF-α and IL-8 cytokine release in M1-differentiated cells, increased IL-10 and CD206 gene expression, as well as IL-10 cytokine release in M0 cells. The specific PEMF stimulation regime, which is optimal in vitro, might have a high potential for a future in vivo translation targeting neural regeneration and anti-inflammatory action for treating peripheral nerve injuries. [ABSTRACT FROM AUTHOR]

Raised life expectancy and aging of the general population are associated with an increased concern for fragility fractures due to factors such as osteoporosis, reduced bone density, and an higher risk of falls. Among these, the most frequent are vertebral compression fractures (VCF), which can be clinically occult. Once the diagnosis is made, generally thorough antero-posterior and lateral views of the affected spine at the radiographs, a comprehensive workup to assess the presence of a metabolic bone disease or secondary causes of osteoporosis and bone frailty is required. Treatment uses a multimodal management consisting of a combination of brace, pain management, bone metabolism evaluation, osteoporosis medication and has recently incorporated biophysical stimulation, a noninvasive technique that uses induced electric stimulation to improve bone recovery through the direct and indirect upregulation of bone morphogenic proteins, stimulating bone formation and remodeling. It contributes to the effectiveness of the therapy, promoting accelerated healing, supporting the reduction of bed rest and pain medications, improving patients’ quality of life, and reducing the risk to undergo surgery in patients affected by VCFs. Therefore, the aim of this review is to outline the fundamental concepts of multimodal treatment for VCF, as well as the present function and significance of biophysical stimulation in the treatment of VCF patients.

Bone is a highly dynamic tissue characterized mainly by the interactions of osteoblasts and osteoclasts. When the healing ability of bone regeneration is disturbed, targeted biophysical stimulations such as electrical stimulation are applied. In this study the indirect effects of electrically stimulated human osteoblasts on osteoclastogenesis were investigated to better understand detailed cellular interactions. Therefore, two different cell developmental stages were examined: peripheral blood mononuclear cells (PBMCs) as precursors and pre-osteoclasts as differentiated cells. Previously, over a 21-day period, human osteoblasts were stimulated with a low-frequency alternating electric field. The supernatants were collected and used for an indirect co-culture of PBMCs and pre-osteoclasts. The cellular viability and the induction of differentiation and activity were analyzed. Further, the secretion of relevant osteoclastic markers was examined. Supernatants of 7 d and 14 d stimulated osteoblasts led to a decrease in the viability of PBMCs and an increased number of cells containing actin ring structures. Supernatants from osteoblasts stimulated over 7 d induced PBMC differentiation and pre-osteoclastic activation. Furthermore, pre-osteoclasts showed varying mRNA transcripts of MCP-1, ACP5, CA2, and CASP8 when cultivated with media from osteoblasts. Supernatants from day 21 did not influence PBMCs at all but increased the viability of pre-osteoclasts. We could show that different time points of stimulated osteoblasts have varying effects on the cells and that changes can be observed due to the differentiation stages of the cells. Through the effects of the indirect stimulation, it was possible to underline the importance of studying not only osteoblastic differentiation and mineralization behavior under electric stimulation but also analyzing changes in osteoclastogenesis and the activity of osteoclasts. [ABSTRACT FROM AUTHOR]

Phalangeal fractures are common events among the upper limbs accounting for 10% of all human body fractures. Fracture complete healing process may persevere several months or years. Most phalangeal fractures present favorable union within 3 to 6 weeks. In the literature, biophysical stimulation has yielded favorable outcomes in the treatment of hand fractures. A survey involving hospitals in the US reported the use of biophysical stimulation (72%) in relation to nonhealing fractures at three months after trauma. A noninvasive procedure such as biophysical stimulation may be preferential prior to consideration of invasive procedures. In this retrospective study, we analyzed 80 phalangeal fractures, 43 of which did not show any radiographic sign of healing 30 days after surgery; on radiograms, we calculated radiographic data and the total active motion (TAM) for clinical comparison. All radiographic images were evaluated using Adobe Photoshop CS3 (version 10.0, Adobe Systems Inc., San Jose, CA, USA). We calculated the index of relative bone healing each month after surgery starting from 30 days, which was considered as T1, and followed up for a total of 6 months after stimulation (T6) with better results in stimulated groups. We concluded that prompt administration of biophysical stimulation supports fracture healing and yields an important improvement in the union rate compared with nontreatment. Above all, our patients experienced less injury-related distress between the fracture and repair period, which consequently reduced immobilization time, envisaging an early rehabilitation interval, with a better patient hand outcome. [ABSTRACT FROM AUTHOR]

Pulsed Electromagnetic Field (PEMF) is a non invasive, therapeutic form of low field magnetic stimulation that has been used for several years to supplement bone healing. It is known to generate pulsating magnetic frequencies within the body that accelerate the process of healing and reduce postoperative pain. The survival rate of dental implants over a 10-year observation has been reported to be higher than 90%. Success of dental implant therapy depends on the quality and quantity of available bone in which they are inserted. Implants with poor early or primary stability frequently may require additional time for osseointegration or may sometimes fail. Development of procedures which accelerate osseointegration of dental implants, reduce the period of healing, and lead to an early rehabilitation of the patient are required for successful oral rehabilitation. The potential for bone repair can be stimulated through non invasive adjunctive treatments such as application of pulsating electromagnetic field therapy, Low-Intensity Pulsed Ultrasound (LIPUS), and Low-Level Laser Therapy (LLLT). These methods of biophysical stimulation of bone union were developed initially to enhance the healing of fractures, healing of bony non unions and have been hypothesised to improve implant osseointegration. This study sought to report latest trends in PEMF Therapy stimulations in oral tissues and its use to enhance the bone repair and regeneration. Pulsed electromagnetic field stimulation to induce bone regeneration mandates a broad range of settings that include magnetic field intensity, frequency, type of signals and duration of application etc. The present study analyses these clinical settings in published human trials and is expected to serve as a treatment guide for the clinicians to bring into their clinical use these strategies to improve bone regeneration and implant osseointegration in deficient and osteoporotic bone. [ABSTRACT FROM AUTHOR]

Abstract Background Multiple strategies have been proposed to promote the differentiation potential of mesenchymal stem cells (MSCs), which is the fundamental property in tissue formation and regeneration. However, these strategies are relatively inefficient that limit the application. In this study, we reported a novel and efficient strategy, nanosecond pulsed electric fields (nsPEFs) stimulation, which can enhance the trilineage differentiation potential of MSCs, and further explained the mechanism behind. Methods We used histological staining to screen out the nsPEFs parameters that promoted the trilineage differentiation potential of MSCs, and further proved the effect of nsPEFs by detecting the functional genes. In order to explore the corresponding mechanism, we examined the expression of pluripotency genes and the methylation status of their promoters. Finally, we targeted the DNA methyltransferase which was affected by nsPEFs. Results The trilineage differentiation of bone marrow-derived MSCs was significantly enhanced in vitro by simply pre-treating with 5 pulses of nsPEFs stimulation (energy levels as 10 ns, 20 kV/cm; 100 ns, 10 kV/cm), due to that the nsPEFs demethylated the promoters of stem cell pluripotency genes OCT4 and NANOG through instantaneous downregulation of DNA methylation transferase 1 (DNMT1), thereby increasing the expression of OCT4 and NANOG for up to 3 days, and created a treatment window period of stem cells. Conclusions In summary, nsPEFs can enhance MSCs differentiation via the epigenetic regulation and could be a safe and effective strategy for future stem cell application.

Pulsed Electromagnetic Field (PEMF) is a non invasive, therapeutic form of low field magnetic stimulation that has been used for several years to supplement bone healing. It is known to generate pulsating magnetic frequencies within the body that accelerate the process of healing and reduce postoperative pain. The survival rate of dental implants over a 10-year observation has been reported to be higher than 90%. Success of dental implant therapy depends on the quality and quantity of available bone in which they are inserted. Implants with poor early or primary stability frequently may require additional time for osseointegration or may sometimes fail. Development of procedures which accelerate osseointegration of dental implants, reduce the period of healing, and lead to an early rehabilitation of the patient are required for successful oral rehabilitation. The potential for bone repair can be stimulated through non invasive adjunctive treatments such as application of pulsating electromagnetic field therapy, Low-Intensity Pulsed Ultrasound (LIPUS), and Low-Level Laser Therapy (LLLT). These methods of biophysical stimulation of bone union were developed initially to enhance the healing of fractures, healing of bony non unions and have been hypothesised to improve implant osseointegration. This study sought to report latest trends in PEMF Therapy stimulations in oral tissues and its use to enhance the bone repair and regeneration. Pulsed electromagnetic field stimulation to induce bone regeneration mandates a broad range of settings that include magnetic field intensity, frequency, type of signals and duration of application etc. The present study analyses these clinical settings in published human trials and is expected to serve as a treatment guide for the clinicians to bring into their clinical use these strategies to improve bone regeneration and implant osseointegration in deficient and osteoporotic bone.

Osteoporosis disrupts the fine-tuned balance between bone formation and resorption, leading to reductions in bone quantity and quality and ultimately increasing fracture risk. Prevention and treatment of osteoporotic fractures is essential for reductions in mortality, morbidity, and the economic burden, particularly considering the aging global population. Extreme bone loss that mimics time-accelerated osteoporosis develops in the paralyzed limbs following complete spinal cord injury (SCI). In vitro nanoscale vibration (1 kHz, 30 or 90 nm amplitude) has been shown to drive differentiation of mesenchymal stem cells toward osteoblast-like phenotypes, enhancing osteogenesis and inhibiting osteoclastogenesis simultaneously. Here, we develop and characterize a wearable device designed to deliver and monitor continuous nanoamplitude vibration to the hindlimb long bones of rats with complete SCI. We investigate whether a clinically feasible dose of nanovibration (two 2 h/day, 5 days/week for 6 weeks) is effective at reversing the established SCI-induced osteoporosis. Laser interferometry and finite element analysis confirmed transmission of nanovibration into the bone, and microcomputed tomography and serum bone formation and resorption markers assessed effectiveness. The intervention did not reverse SCI-induced osteoporosis. However, serum analysis indicated an elevated concentration of the bone formation marker procollagen type 1 N -terminal propeptide (P1NP) in rats receiving 40 nm amplitude nanovibration, suggesting increased synthesis of type 1 collagen, the major organic component of bone. Therefore, enhanced doses of nanovibrational stimulus may yet prove beneficial in attenuating/reversing osteoporosis, particularly in less severe forms of osteoporosis.

Osteoarthritis (OA) is the most prevalent degenerative joint disease and the main cause of pain and disability in elderly people. OA currently represents a significant social health problem, since it affects 250 million individuals worldwide, mainly adults aged over 65. Although OA is a multifactorial disease, depending on both genetic and environmental factors, it is reported that joint degeneration has a higher prevalence in former athletes. Repetitive impact and loading, joint overuse and recurrent injuries followed by a rapid return to the sport might explain athletes’ predisposition to joint articular degeneration. In recent years, however, big efforts have been made to improve the prevention and management of sports injuries and to speed up the athletes’ return-to-sport. Biophysics is the study of biological processes and systems using physics-based methods or based on physical principles. Clinical biophysics has recently evolved as a medical branch that investigates the relationship between the human body and non-ionizing physical energy. A physical stimulus triggers a biological response by regulating specific intracellular pathways, thus acting as a drug. Preclinical and clinical trials have shown positive effects of biophysical stimulation on articular cartilage, subchondral bone and synovia. This review aims to assess the role of pulsed electromagnetic fields (PEMFs) and extracorporeal shockwave therapy (ESWT) in the prevention and treatment of joint degeneration in athletes. [ABSTRACT FROM AUTHOR]

Bone is a highly dynamic tissue characterized mainly by the interactions of osteoblasts and osteoclasts. When the healing ability of bone regeneration is disturbed, targeted biophysical stimulations such as electrical stimulation are applied. In this study the indirect effects of electrically stimulated human osteoblasts on osteoclastogenesis were investigated to better understand detailed cellular interactions. Therefore, two different cell developmental stages were examined: peripheral blood mononuclear cells (PBMCs) as precursors and pre-osteoclasts as differentiated cells. Previously, over a 21-day period, human osteoblasts were stimulated with a low-frequency alternating electric field. The supernatants were collected and used for an indirect co-culture of PBMCs and pre-osteoclasts. The cellular viability and the induction of differentiation and activity were analyzed. Further, the secretion of relevant osteoclastic markers was examined. Supernatants of 7 d and 14 d stimulated osteoblasts led to a decrease in the viability of PBMCs and an increased number of cells containing actin ring structures. Supernatants from osteoblasts stimulated over 7 d induced PBMC differentiation and pre-osteoclastic activation. Furthermore, pre-osteoclasts showed varying mRNA transcripts of MCP-1, ACP5, CA2, and CASP8 when cultivated with media from osteoblasts. Supernatants from day 21 did not influence PBMCs at all but increased the viability of pre-osteoclasts. We could show that different time points of stimulated osteoblasts have varying effects on the cells and that changes can be observed due to the differentiation stages of the cells. Through the effects of the indirect stimulation, it was possible to underline the importance of studying not only osteoblastic differentiation and mineralization behavior under electric stimulation but also analyzing changes in osteoclastogenesis and the activity of osteoclasts.

Phalangeal fractures are common events among the upper limbs accounting for 10% of all human body fractures. Fracture complete healing process may persevere several months or years. Most phalangeal fractures present favorable union within 3 to 6 weeks. In the literature, biophysical stimulation has yielded favorable outcomes in the treatment of hand fractures. A survey involving hospitals in the US reported the use of biophysical stimulation (72%) in relation to nonhealing fractures at three months after trauma. A noninvasive procedure such as biophysical stimulation may be preferential prior to consideration of invasive procedures. In this retrospective study, we analyzed 80 phalangeal fractures, 43 of which did not show any radiographic sign of healing 30 days after surgery; on radiograms, we calculated radiographic data and the total active motion (TAM) for clinical comparison. All radiographic images were evaluated using Adobe Photoshop CS3 (version 10.0, Adobe Systems Inc., San Jose, CA, USA). We calculated the index of relative bone healing each month after surgery starting from 30 days, which was considered as T1, and followed up for a total of 6 months after stimulation (T6) with better results in stimulated groups. We concluded that prompt administration of biophysical stimulation supports fracture healing and yields an important improvement in the union rate compared with nontreatment. Above all, our patients experienced less injury-related distress between the fracture and repair period, which consequently reduced immobilization time, envisaging an early rehabilitation interval, with a better patient hand outcome.

Ample proof showed that non‐coding RNAs (ncRNAs) play a crucial role in proliferation and differentiation of osteoblasts and bone marrow stromal cells (BMSCs). Varied forms of biophysical stimuli like mechanical strain, fluid shear stress (FSS), microgravity and vibration are verified to regulate ncRNAs expression in osteogenic differentiation and influence the expression of target genes associated with osteogenic differentiation and ultimately regulate bone formation. The consequences of biophysical stimulation on osteogenic differentiation validate the prospect of exercise for the prevention and treatment of osteoporosis. In this review, we tend to summarize the studies on regulation of osteogenic differentiation by ncRNAs beneath biophysical stimulation and facilitate to reveal the regulatory mechanism of biophysical stimulation on ncRNAs, and provide an update for the prevention of bone metabolism diseases by exercise. [ABSTRACT FROM AUTHOR]

Cellular reprogramming technologies have been developed with different physicochemical factors to improve the reprogramming efficiencies of induced pluripotent stem cells (iPSCs). Ultrasound is a clinically applied noncontact biophysical factor known for regulating various cellular behaviors but remains uninvestigated for cellular reprogramming. Here, we present a new reprogramming strategy using low-intensity ultrasound (LIUS) to improve cellular reprogramming of iPSCs in vitro and in vivo. Under 3D microenvironment conditions, increased LIUS stimulation shows enhanced cellular reprogramming of the iPSCs. The cellular reprogramming process facilitated by LIUS is accompanied by increased mesenchymal to epithelial transition and histone modification. LIUS stimulation transiently modulates the cytoskeletal rearrangement, along with increased membrane fluidity and mobility to increase HA/CD44 interactions. Furthermore, LIUS stimulation with HA hydrogel can be utilized in application of both human cells and in vivo environment, for enhanced reprogrammed cells into iPSCs. Thus, LIUS stimulation with a combinatorial 3D microenvironment system can improve cellular reprogramming in vitro and in vivo environments, which can be applied in various biomedical fields., Competing Interests: The authors declare no conflicts of interest., (© 2024 The Authors.)

Background: Multiple strategies have been proposed to promote the differentiation potential of mesenchymal stem cells (MSCs), which is the fundamental property in tissue formation and regeneration. However, these strategies are relatively inefficient that limit the application. In this study, we reported a novel and efficient strategy, nanosecond pulsed electric fields (nsPEFs) stimulation, which can enhance the trilineage differentiation potential of MSCs, and further explained the mechanism behind. Methods: We used histological staining to screen out the nsPEFs parameters that promoted the trilineage differentiation potential of MSCs, and further proved the effect of nsPEFs by detecting the functional genes. In order to explore the corresponding mechanism, we examined the expression of pluripotency genes and the methylation status of their promoters. Finally, we targeted the DNA methyltransferase which was affected by nsPEFs. Results: The trilineage differentiation of bone marrow-derived MSCs was significantly enhanced in vitro by simply pre-treating with 5 pulses of nsPEFs stimulation (energy levels as 10 ns, 20 kV/cm; 100 ns, 10 kV/cm), due to that the nsPEFs demethylated the promoters of stem cell pluripotency genes OCT4 and NANOG through instantaneous downregulation of DNA methylation transferase 1 (DNMT1), thereby increasing the expression of OCT4 and NANOG for up to 3 days, and created a treatment window period of stem cells. Conclusions: In summary, nsPEFs can enhance MSCs differentiation via the epigenetic regulation and could be a safe and effective strategy for future stem cell application. [ABSTRACT FROM AUTHOR]

Compared to two-dimensional cell cultures, three-dimensional ones potentially allow recreating natural tissue environments with higher accuracy. The three-dimensional approach is being investigated in the field of tissue engineering targeting the reconstruction of various tissues, among which skeletal muscle. Skeletal muscle is an electroactive tissue which strongly relies upon interactions with the extracellular matrix for internal organization and mechanical function. Studying the optimization of myogenesis in vitro implies focusing on appropriate biomimetic stimuli, as biochemical and electrical ones. Here we present a three-dimensional polyurethane-based soft porous scaffold (porosity ~ 86%) with a Young's modulus in wet conditions close to the one of natural skeletal muscle tissue (~ 9 kPa). To study the effect of external stimuli on muscle cells, we functionalized the scaffold with extracellular matrix components (laminin and fibronectin) and observed an increase in myoblast proliferation over three days. Furthermore, the combination between laminin coating and electrical stimulation resulted in more spread and thicker myotubes compared to non-stimulated samples and samples receiving the single (non-combined) inputs. These results pave the way to the development of mature muscle tissue within three-dimensional soft scaffolds, through the combination of biochemical and electrical stimuli. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is the most prevalent degenerative joint disease and the main cause of pain and disability in elderly people. OA currently represents a significant social health problem, since it affects 250 million individuals worldwide, mainly adults aged over 65. Although OA is a multifactorial disease, depending on both genetic and environmental factors, it is reported that joint degeneration has a higher prevalence in former athletes. Repetitive impact and loading, joint overuse and recurrent injuries followed by a rapid return to the sport might explain athletes’ predisposition to joint articular degeneration. In recent years, however, big efforts have been made to improve the prevention and management of sports injuries and to speed up the athletes’ return-to-sport. Biophysics is the study of biological processes and systems using physics-based methods or based on physical principles. Clinical biophysics has recently evolved as a medical branch that investigates the relationship between the human body and non-ionizing physical energy. A physical stimulus triggers a biological response by regulating specific intracellular pathways, thus acting as a drug. Preclinical and clinical trials have shown positive effects of biophysical stimulation on articular cartilage, subchondral bone and synovia. This review aims to assess the role of pulsed electromagnetic fields (PEMFs) and extracorporeal shockwave therapy (ESWT) in the prevention and treatment of joint degeneration in athletes.

Bone-forming cells build mineralized microstructure and couple with bone-resorbing cells, harmonizing bone mineral acquisition, and remodeling to maintain bone mass homeostasis. Mitochondrial glycolysis and oxidative phosphorylation pathways together with ROS generation meet the energy requirement for bone-forming cell growth and differentiation, respectively. Moderate mechanical stimulations, such as weight loading, physical activity, ultrasound, vibration, and electromagnetic field stimulation, etc., are advantageous to bone-forming cell activity, promoting bone anabolism to compromise osteoporosis development. A plethora of molecules, including ion channels, integrins, focal adhesion kinases, and myokines, are mechanosensitive and transduce mechanical stimuli into intercellular signaling, regulating growth, mineralized extracellular matrix biosynthesis, and resorption. Mechanical stimulation changes mitochondrial respiration, biogenesis, dynamics, calcium influx, and redox, whereas mechanical disuse induces mitochondrial dysfunction and oxidative stress, which aggravates bone-forming cell apoptosis, senescence, and dysfunction. The control of the mitochondrial biogenesis activator PGC-1α by NAD+-dependent deacetylase sirtuins or myokine FNDC/irisin or repression of oxidative stress by mitochondrial antioxidant Nrf2 modulates the biophysical stimulation for the promotion of bone integrity. This review sheds light onto the roles of mechanosensitive signaling, mitochondrial dynamics, and antioxidants in mediating the anabolic effects of biophysical stimulation to bone tissue and highlights the remedial potential of mitochondrial biogenesis regulators for osteoporosis.

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 A2A 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. [ABSTRACT FROM AUTHOR]

While several studies investigated the effects of mechanical or electrical stimulation on osseointegration and bone fracture healing, little is known about the molecular and cellular impact of combined biophysical stimulation on peri-implant osseointegration. Therefore, we established an in vitro system, capable of applying shear stress and electric fields simultaneously. Capacitively coupled electric fields were used for electrical stimulation, while roughened Ti6Al4V bodies conducted harmonically oscillating micromotions on collagen scaffolds seeded with human osteoblasts. Different variations of single and combined stimulation were applied for three days, while samples loaded with Ti6Al4V bodies and untreated samples served as control. Metabolic activity, expression of osteogenic markers and bone remodeling markers were investigated. While combined stimulation showed no substantial benefit compared to sole mechanical stimulation, we observed that 25 µm micromotions applied by roughened Ti6Al4V bodies led to a significant increase in gene expression of osteocalcin and tissue inhibitor of metalloprotease 1. Additionally, we found an increase in metabolic activity and expression of bone remodeling markers with reduced procollagen type 1 synthesis after 100 mVRMS electrical stimulation. We were able to trigger specific cellular behaviors using different biophysical stimuli. In future studies, different variations of electrical stimulation will be combined with interfacial micromotions.

Raised life expectancy and aging of the general population are associated with an increased concern for fragility fractures due to factors such as osteoporosis, reduced bone density, and an higher risk of falls. Among these, the most frequent are vertebral compression fractures (VCF), which can be clinically occult. Once the diagnosis is made, generally thorough antero-posterior and lateral views of the affected spine at the radiographs, a comprehensive workup to assess the presence of a metabolic bone disease or secondary causes of osteoporosis and bone frailty is required. Treatment uses a multimodal management consisting of a combination of brace, pain management, bone metabolism evaluation, osteoporosis medication and has recently incorporated biophysical stimulation, a noninvasive technique that uses induced electric stimulation to improve bone recovery through the direct and indirect upregulation of bone morphogenic proteins, stimulating bone formation and remodeling. It contributes to the effectiveness of the therapy, promoting accelerated healing, supporting the reduction of bed rest and pain medications, improving patients' quality of life, and reducing the risk to undergo surgery in patients affected by VCFs. Therefore, the aim of this review is to outline the fundamental concepts of multimodal treatment for VCF, as well as the present function and significance of biophysical stimulation in the treatment of VCF patients., Competing Interests: The authors have no relevant financial or non-financial interests to disclose., (© 2023 The Authors. Published by Elsevier B.V. on behalf of Research Network of Computational and Structural Biotechnology.)

Biophysical stimulations with electric and electromagnetic fields have been demonstrated to accelerate the bone-healing rate. This study has been designed to investigate the effects of electricity directly connected with the central pins of an external fixator in an experimental osteotomy model in sheep. Thirty mg/kg of tetracycline chloride were administered on the 30th and on the 45th day after surgery for histomorphometric studies. Plain radiographs were obtained in standard projections every 15 days after surgery and were analyzed with a software program (Corel Photo-Paint Pro X2, Corel Corporation, Ottawa, Canada). The specimens obtained after 60 days were examined with histological analysis. The results show that biophysical treatment with alternating electricity in combination with external fixator enhances new-bone formation. The translational value of this study, due to the similarities between ovine and human species, suggests that this treatment could be useful in speeding the bone-healing rate both in animals and humans.

ABSTRACT In vitro manipulation of human stem cells is a critical process in regenerative medicine and cellular therapies. Strategies and methods to maintain stem cells and direct them into specific lineages are ongoing challenges in these fields. To date, a number of studies have reported that besides biochemical stimulation, biophysical cues in the form of surface patterning and external stimulation also influence stem cell attachment, proliferation, and differentiation, and can be used in cell reprogramming and the maintenance of pluripotency. While biochemical cues are generally effective and easy to deliver, biophysical cues have many other advantages for scalability as they are cost efficient, have a longer lifetime, and can be easily defined. However, different protocols and cell sources utilized in a variety of studies have led to difficulties in obtaining clear conclusions about the effects of the biophysical environment on stem cells. In addition, the examination of different types of external stimulation is time consuming and limited by available fabrication techniques, resulting in a delay in commercialization and clinical applications. In this review, we aim to summarize the most important biophysical cues and methods for the culture of human stem cells, including mesenchymal and pluripotent stem cells, to facilitate their adoption in stem cell biology. The standard classical protocols of using biochemical cues will also be discussed for comparison. We believe that combining biochemical and biophysical stimulation has the greatest potential to generate functionally mature cells at a scalable and inexpensive rate for diverse applications in regenerative medicine and cell therapy. Biotechnol. Bioeng. 2017;114: 260-280. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Until as recently as a century ago, the exposure of biological systems to radiation was limited only to the natural sources. Today, however, a broad range of radiation types and doses have found a wide variety of uses and applications, so much so that it would be difficult to make a list of all the areas of human activity in which radiation is used for one purpose or another. The study of radiation effects on individuals and populations as a whole has become important only with the development of methods and sources of man-made radiation. Given that what is present in this case are physical effects on biological systems (living organisms), all these methods can be placed under the heading of biophysical influences. In the last 50 years, the effects of extremely low-frequency electromagnetic fields (ELF-EMF) have been studied with great diligence. These fields are the ones most commonly found in the human environment and they have been used in our studies in this field. The present paper provides a brief review of the literature data and our findings on the effects of ELF-EMF on various crop species using the RIES (Resonant Impulse Electromagnetic Stimulation) method, developed at the Faculty of Agriculture of the University of Novi Sad.

Objective . In this study, we aimed to verify the beneficial effects of low-intensity pulsed ultrasound (LIPUS) stimulation on two cell types: H 2 O 2 -treated RSC96 Schwann cells and THP-1 macrophages, used to model neuropathic inflammation. Approach . Using a set-up guaranteeing a fine control of the ultrasound dose at the target, different frequencies (38 kHz, 1 MHz, 5 MHz) and different intensities (20, 100, 500 mW cm -2 ) were screened to find the most effective experimental conditions for triggering beneficial effects on metabolic activity and release of neurotrophic cytokines ( β -nerve growth factor, brain-derived neurotrophic factor, glial cell-derived neurotrophic factor) of RSC96 cells. The combination of parameters resulting the optimal one was applied to evaluate anti-inflammatory effects in terms of reactive oxygen species (ROS) and tumor necrosis factor- α (TNF- α ) production, also investigating a possible anti-oxidant activity and mechanotransduction pathway for the anti-inflammatory process. The same optimal combination of parameters was then applied to THP-1 cells, differentiated into M1 and M2 phenotypes, to assess the effect on the expression and release of pro-inflammatory markers (TNF- α , interleukin (IL)-1 β , IL-6, IL-8) and anti-inflammatory ones (IL-10 and CD206). Main results. 5 MHz and 500 mW cm -2 were found as the optimal stimulation parameters on RSC96 cells. Such parameters were also found to suppress ROS and TNF- α in the same cell line, thus highlighting a possible anti-inflammatory effect, involving the NF-kB pathway. An anti-oxidant effect induced by LIPUS was also observed. Finally, the same LIPUS parameters did not induce any differentiation towards the M1 phenotype of THP-1 cells, whereas they decreased TNF- α and IL-8 gene expression, reduced IL-8 cytokine release and increased IL-10 cytokine release in M1-polarized THP-1 cells. Significance. This study represents the first step towards the use of precisely controlled LIPUS for the treatment of peripheral neuropathies., (© 2023 IOP Publishing Ltd.)

Background: Osteochondral defects (OCDs) of the talus usually affect athletic patients. The primary surgical treatment consists of arthroscopic debridement and microfracture. Various possibilities have been suggested to improve the recovery process after debridement and microfracture. A potential solution to obtain this goal is the application of pulsed electromagnetic fields (PEMFs), which stimulate the repair process of bone and cartilage. Hypothesis: The use of PEMFs after arthroscopic debridement and microfracture of an OCD of the talus leads to earlier resumption of sports and an increased number of patients that resume sports. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 68 patients were randomized to receive either PEMFs (n = 36) or placebo (n = 32) after arthroscopic treatment of an OCD of the talus. The primary outcomes (ie, the number of patients who resumed sports and time to resumption of sports) were analyzed with Kaplan-Meier curves as well as Mann-Whitney U, chi-square, and log-rank tests. Secondary functional outcomes were assessed with questionnaires (American Orthopaedic Foot and Ankle Society ankle-hindfoot score, Foot and Ankle Outcome Score, EuroQol, and numeric rating scales for pain and satisfaction) at multiple time points up to 1-year follow-up. To assess bone repair, computed tomography scans were obtained at 2 weeks and 1 year postoperatively. Results: Almost all outcome measures improved significantly in both groups. The percentage of sport resumption (PEMF, 79%; placebo, 80%; P = .95) and median time to sport resumption (PEMF, 17 weeks; placebo, 16 weeks; P = .69) did not differ significantly between the treatment groups. Likewise, there were no significant between-group differences with regard to the secondary functional outcomes and the computed tomography results. Conclusion: PEMF does not lead to a higher percentage of patients who resume sports or to earlier resumption of sports after arthroscopic debridement and microfracture of talar OCDs. Furthermore, no differences were found in bone repair between groups. Registration: Netherlands Trial Register NTR1636. [ABSTRACT FROM AUTHOR]

Treatment refractory depression (TRD) in the elderly is a common psychiatric disorder with high comorbidity and mortality. Older adults with TRD often have complicated comorbidities and several predisposing risk factors, which may lead to neuropsychiatric dysfunction and poor response to treatment. Several hypotheses suggest the underlying mechanisms, including vascular, immunological, senescence, or abnormal protein deposition. Treatment strategies for TRD include optimization of current medication dose, augmentation, switching to an alternative agent or class, and combination of different antidepressant classes, as well as nonpharmacological adjuvant interventions such as biophysical stimulation and psychotherapy. In summary, treatment recommendations for TRD in the elderly favor a multimodal approach, combining pharmacological and nonpharmacological treatments., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Because osteoblasts play a key role in bone remodeling and the influence of low-level laser therapy on this process is not clear, Saos-2 human osteoblast-like cells were irradiated by a gallium--aluminum--arsenide diode laser (915 nm) for 10, 48, 96, 193, and 482 s using doses 1, 5, 10, 20, and 50 J/cm², respectively. A control group was not irradiated. Morphology, viability, and cytotoxicity analyses were carried out after 1 hr, 1 day, and 3 days. Deoxyribose nucleic acid (DNA) content and release of vascular endothelial growth factor (VEGF), receptor activator of nuclear factor kappa B ligand (RANKL), and osteoprotegerin (OPG) were evaluated. Viability was modulated by laser irradiation in a dose-dependent manner, with 10 J/cm² inducing a biostimulatory response and 20 to 50 J/cm determining a bioinhibitory and cytotoxic effect. Accordingly, DNA content was generally increased for the 10 J/cm² dose and decreased for the 50 J/cm² dose. A rapid and transitory trend toward increased RANKL/OPG ratio and a tendency toward a delayed increase in VEGF release for doses of 1 to 10 J/cm² was found. Further investigations using the biostimulatory dose of 10 J/cm² emerged from this study are needed to establish the ideal treatment regimens in the laboratory as well as in clinical practice. [ABSTRACT FROM AUTHOR]

The article discusses a study which examined the effects of pulsed electromagnetic fields (PEMFs) on patients who underwent bone marrow-derived cells (BMDCs) transplantation for osteochondral lesions of the talus (OLT). Topics covered include the advantages of biophysical stimulation with PEMFs, the superior clinical outcome found in the group with higher American Orthopaedic Foot and Ankle Society (AOFAS) score and the pain control experienced after biophysical stimulation.

Objectives: Acute cerebral ischemia is characterized by several pathological processes evolving during time, which contribute to the final tissue damage. Secondary processes, such as prolonged inflammatory response, impaired mitochondrial function, and oxidative stress, are responsible for the progression of brain injury to the peri-infarct area, called "penumbra." Adenosine has been shown to play a crucial role in regulating the inflammatory cascade following brain ischemia. Pulsed electromagnetic fields (PEMFs) act as modulators of adenosine receptors, increasing the functionality of the endogenous adenosine. In particular, PEMF exposure induces a significant upregulation of A 2A and A 3 adenosine receptors in different neuronal cell types. Several lines of evidence suggest that PEMF exposure might play a neuroprotective role after ischemic damage., Materials and Methods: This review summarizes the current knowledge on the mechanism of action of PEMFs and their biological effects on neuronal damage both in preclinical and clinical studies., Results: PEMFs counteract hypoxia-induced apoptosis and ROS production in neuronal-like cells and exert a strong anti-inflammatory effect on microglial cells. Data from stroke animal models showed that PEMFs exposure is able to reduce the size of the infarct area and decrease the levels of pro-inflammatory mediators. In clinical studies, PEMFs stimulation proved to be safe and well tolerated. Preliminary results on acute ischemic stroke patients showed a dose-dependent reduction in the lesion size., Conclusions: Altogether, these data demonstrate the efficacy of PEMFs against several mechanisms underlying ischemic damage and suggest that PEMFs might represent a novel noninvasive adjunctive treatment for acute ischemic stroke, providing neuroprotection and reducing functional deficits following ischemia., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

It remains unclear how specific mechanical signals generated by applied dynamic compression (DC) regulate chondrocyte biosynthetic activity. It has previously been suggested that DC-induced interstitial fluid flow positively impacts cartilage-specific matrix production. Modifying fluid flow within dynamically compressed hydrogels therefore represents a promising approach to controlling chondrocyte behavior, which could potentially be achieved by changing the construct architecture. The objective of this study was to first determine the influence of construct architecture on the mechanical environment within dynamically compressed agarose hydrogels using finite element (FE) modeling and to then investigate how chondrocytes would respond to this altered environment. To modify construct architecture, an array of channels was introduced into the hydrogels. Increased magnitudes of fluid flow were predicted in the periphery of dynamically compressed solid hydrogels and also around the channels in the dynamically compressed channeled hydrogels. DC was found to significantly increase sGAG synthesis in solid constructs, which could be attributed at least in part to an increase in DNA. DC was also found to preferentially increase collagen accumulation in regions of solid and channeled constructs where FE modeling predicted higher levels of fluid flow, suggesting that this stimulus is important for promoting collagen production by chondrocytes embedded in agarose gels. In conclusion, this study demonstrates how the architecture of cell-seeded scaffolds or hydrogels can be modified to alter the spatial levels of biophysical cues throughout the construct, leading to greater collagen accumulation throughout the engineered tissue rather than preferentially in the construct periphery. This system also provides a novel approach to investigate how chondrocytes respond to altered levels of biophysical stimulation. [ABSTRACT FROM AUTHOR]

Background and Purpose Exogenous electromagnetic fields (EMFs) affect bone metabolism, but the mechanisms responsible for this phenomenon are unclear. Pulsed EMFs (PEMFs) can be effective in the management of congenital pseudarthrosis or delayed union or non-union of fractures. We investigated the effects of PEMFs used in clinical practice on human osteoblast cultures. Methods Primary osteoblastic cells were isolated from a human femoral head. Cultures were exposed to the PEMF stimulation for 72 hours, 7 and 10 days and compared with a control group of primary osteoblastic cells non-exposed to PEMF. Cell growth and alkaline phosphatase activity were evaluated in the osteoblast cell cultures at each observation time. Results At each observation time, the differences in cell numbers between PEMF-exposed cells and control group were statistically significant ( p < 0.05). The alkaline phosphatase-specific activity of PEMF-exposed osteoblast cultures showed a statistically significant ( p < 0.05) increase when compared with the control group after 7 and 10 days of exposure. Conclusions The application of PEMF stimulation on human osteoblasts accelerates cellular proliferation when compared with a control group of non-PEMF-exposed cells. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

[Display omitted] The field of bioelectronic medicine has witnessed significant developments over the last two decades. However, the ability to precisely control the cell functionalities remains a major constraint in translating research outcomes to implantable bioelectronic devices. Various biophysical cues such as matrix stiffness, mechanical forces, substrate topography, and external electrical stimulation are being investigated to modulate cellular functions. In this perspective, the bioengineering approach of integrating electronic systems with biomaterial scaffolds can be adapted to monitor the cellular physiology within the engineered tissue. In this critical review, we have comprehensively analysed the applications of electroactive biomaterials to deliver bioelectrical cues for regulating cell fate processes. Along with the fundamental physical phenomenon at the tissue-electrode interface, the advancements in nanoelectronic devices in pre-clinical and clinical studies have been summarized. While the stiff and rigid electronics bring-forth the challenges in the biointegration and electrical performance; soft and flexible electronics, in contrast, have emerged as next-generation bioelectronic devices with a more stable and compatible biointerface. We have outlined various state-of-the-art approaches to develop bioresorbable electronics that can be eliminated from the body after a stipulated time, without further intervention. In addition, clinically-led bioelectronics medicine to regulate the electrical signaling at the neural interface has been highlighted. In summary, this review envisions the strategies of biomaterials-based biophysical stimulations to be adopted in bioelectronics-based advanced tissue engineering approaches that may eventually allow us to potentially realize the development of bioartificial organs. [ABSTRACT FROM AUTHOR]

• LIPUS stimulation set-ups able to precisely control the dose delivered to cells. • Full control of ultrasound stimulation parameters. • Novel biological sample-retaining system solution which guarantees in vitro sterility. • Absence of toxic and inflammatory effects on cells retained within the system. • Highly-controlled sonication experiments on cells. This work aims to describe the development and validation of two low-intensity pulsed ultrasound stimulation systems able to control the dose delivered to the biological target. Transducer characterization was performed in terms of pressure field shape and intensity, for a high-frequency range (500 kHz to 5 MHz) and for a low-frequency value (38 kHz). This allowed defining the distance, on the beam axis, at which biological samples should be placed during stimulation and to exactly know the intensity at the target. Carefully designed retaining systems were developed, for hosting biological samples. Sealing tests proved their impermeability to external contaminants. The assembly/de-assembly time of the systems resulted ~3 min. Time-domain acoustic simulations allowed to precisely estimate the ultrasound beam within the biological sample chamber, thus enabling the possibility to precisely control the pressure to be transmitted to the biological target, by modulating the transducer's input voltage. Biological in vitro tests were also carried out, demonstrating the sterility of the system and the absence of toxic and inflammatory effects on growing cells after multiple immersions in water, over seven days. [ABSTRACT FROM AUTHOR]