Nonunion fracture healing: Evaluation of effectiveness of demineralized bone matrix and mesenchymal stem cells in a novel sheep bone nonunion model

Immunomodulation Pathogenesis and Treatment of Bone Nonunion

Fractures and bone nonunion commonly require surgical intervention. Serious outcomes of non-healing in the late stages of fracture place a significant financial burden on society and families. Bone nonunion occurs when a fracture stops healing, for many reasons, and leads to a variety of bad outcomes. Numerous factors, including biomechanics and immunology, are involved in the complicated mechanisms of bone nonunion. The immune-inflammatory response plays a significant part in the emergence of bone nonunion, and the occurrence, control, and remission of inflammation in the bone healing process have a significant influence on the ultimate success of bone tissue repair. In the bone microenvironment, immune cells and associated cytokines control bone repair, which is significantly influenced by macrophages, T cells, and fibroblast growth factor. To limit acute inflammation and  balance osteogenesis and osteoblastogenesis for tissue repair and regeneration, immune cells and various cytokines in the local microenvironment must be precisely regulated. As a bad complication of late-stage fractures, bone nonunion has a significant effect on patients' quality of life and socioeconomic development. Therefore, in-depth research on its pathogenesis and treatment methods has important clinical value. To provide more precise, focused therapeutic options for the treatment of bone nonunion, we discuss the regulatory roles of the key immune cells engaged in bone healing within the microenvironment during bone healing and their effect on osteogenesis.

The bone nonunion microenvironment: A place where osteogenesis struggles with osteoclastic capacity

Bone nonunion is a common and serious orthopedic disorder, the occurrence of which is associated with a disruption of the dynamic balance between osteoblasts and osteoclasts during bone repair. However, the critical molecular mechanisms affecting this homeostasis are not well understood, and it is essential to investigate the specific components of this mechanism and to restore the balance between osteoblasts and osteoclasts to promote bone repair. First, we defined this complex local environmental factor as the "bone nonunion microenvironment" and identified the importance of the "struggle" between osteoblasts and osteoclasts, which is the most essential element in determining the process of repair. On this basis, we also explored the cellular factors that influence osteogenesis and the molecular signals that influence the balance between osteoclast and osteoblasts, which are important for restoring homeostasis. Further, we explored other factors involved in osteogenesis, such as the biomechanical environment, the nutritional environment, the acid-base environment, and the temperature environment, which are important players in osteogenesis. In conclusion, we found that the balance between osteoblasts and osteoclasts is the essence of bone healing, which is based on the "bone nonunion microenvironment". Therefore, investigating the role of the bone nonunion microenvironment in the system of osteoblast-osteoclast "struggle" provides an important basis for further understanding of the mechanism of nonunion and the development of new therapeutic approaches.

Bioinformatics Analysis and Experimental Validation of Differential Genes and Pathways in Bone Nonunions

Non-union fractures pose a significant clinical challenge, often leading to prolonged pain and disability. Understanding the molecular mechanisms underlying non-union fractures is crucial for developing effective therapeutic interventions. This study integrates bioinformatics analysis and experimental validation to unravel key genes and pathways associated with non-union fractures. We identified differentially expressed genes (DEGs) between non-union and fracture healing tissues using bioinformatics techniques. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were employed to elucidate the biological processes and pathways involved. Common DEGs were identified, and a protein-protein interaction (PPI) network was constructed. Fibronectin-1 (FN1), Thrombospondin-1 (THBS1), and Biglycan (BGN) were pinpointed as critical target genes for non-union fracture treatment. Experimental validation involved alkaline phosphatase (ALP) and Alizarin Red staining to confirm osteogenic differentiation. Our analysis revealed significant alterations in pathways related to cell behavior, tissue regeneration, wound healing, infection, and immune responses in non-union fracture tissues. FN1, THBS1, and BGN were identified as key genes, with their upregulation indicating potential disruptions in the bone remodeling process. Experimental validation confirmed the induction of osteogenic differentiation. The study provides comprehensive insights into the molecular mechanisms of non-union fractures, emphasizing the pivotal roles of FN1, THBS1, and BGN in extracellular matrix dynamics and bone regeneration. The findings highlight potential therapeutic targets and pathways for further investigation. Future research should explore interactions between these genes, validate results using in vivo fracture models, and develop tailored treatment strategies for non-union fractures, promising significant advances in clinical management.

Refinement in Post-Operative Care for Orthopaedic Models: Implementing a Sheep Walking Cast (SWC) for Effective Tibial Fracture Management

In the healthcare system, lower leg fractures remain relevant, incurring costs related to surgical treatment, hospitalization, and rehabilitation. The duration of treatment may vary depending on the individual case and its severity. Casting as a post-surgical fracture treatment is a common method in human and experimental veterinary medicine. Despite the high importance of sheep in preclinical testing materials for osteosynthesis, there is no standardised cast system ensuring proper stabilisation and functionality of hind limbs during the healing of tibia fractures or defects. Existing treatment approaches for tibial osteosynthesis in laboratory animal science include sling hanging, external fixators, or former Achilles tendon incision. These methods restrict animal movement for 4-6 weeks, limit species-typical behaviour, and impact social interactions. Our pilot study introduces a Standardised Walking Cast (SWC) for sheep, enabling immediate physiological movement post surgery. Seven Rhone sheep (female, 63.5 kg ± 6.45 kg) each with a single tibia defect (6 mm mechanical drilled defect) underwent SWC application for 4 weeks after plate osteosynthesis. The animals bore weight on their operated leg from day one, exhibiting slight lameness (grade 1-2 out of 5). Individual step lengths showed good uniformity (average deviation: 0.89 cm). Group housing successfully started on day three after surgery. Weekly X-rays and cast changes ensured proper placement, depicting the healing process. This study demonstrates the feasibility of using an SWC for up to 72 kg of body weight without sling hanging via ceiling mounting or external fixation techniques. Allowing species-typical movement and social behaviour can significantly improve the physiological behaviour of sheep in experiments, contributing to refinement.

Angle-stable interlocking nailing in a canine critical-sized femoral defect model for bone regeneration studies: In pursuit of the principle of the 3R’s

Introduction: Critical-sized long bone defects represent a major therapeutic challenge and current treatment strategies are not without complication. Tissue engineering holds much promise for these debilitating injuries; however, these strategies often fail to successfully translate from rodent studies to the clinical setting. The dog represents a strong model for translational orthopedic studies, however such studies should be optimized in pursuit of the Principle of the 3R’s of animal research (replace, reduce, refine). The objective of this study was to refine a canine critical-sized femoral defect model using an angle-stable interlocking nail (AS-ILN) and reduce total animal numbers by performing imaging, biomechanics, and histology on the same cohort of dogs.

Methods: Six skeletally mature hounds underwent a 4 cm mid-diaphyseal femoral ostectomy followed by stabilization with an AS-ILN. Dogs were assigned to autograft (n = 3) or negative control (n = 3) treatment groups. At 6, 12, and 18 weeks, healing was quantified by ordinal radiographic scoring and quantified CT. After euthanasia, femurs from the autograft group were mechanically evaluated using an established torsional loading protocol. Femurs were subsequently assessed histologically.

Results: Surgery was performed without complication and the AS-ILN provided appropriate fixation for the duration of the study. Dogs assigned to the autograft group achieved radiographic union by 12 weeks, whereas the negative control group experienced non-union. At 18 weeks, median bone and soft tissue callus volume were 9,001 mm³ (range: 4,939–10,061) for the autograft group and 3,469 mm³ (range: 3,085–3,854) for the negative control group. Median torsional stiffness for the operated, autograft treatment group was 0.19 Nm/° (range: 0.19–1.67) and torque at failure was 12.0 Nm (range: 1.7–14.0). Histologically, callus formation and associated endochondral ossification were identified in the autograft treatment group, whereas fibrovascular tissue occupied the critical-sized defect in negative controls.

Conclusion: In a canine critical-sized defect model, the AS-ILN and described outcome measures allowed refinement and reduction consistent with the Principle of the 3R’s of ethical animal research. This model is well-suited for future canine translational bone tissue engineering studies.

Different Protocols of Combined Application of Photobiomodulation In Vitro and In Vivo Plus Adipose-Derived Stem Cells Improve the Healing of Bones in Critical Size Defects in Rat Models

Introduction: Long bone segmental deficiencies are challenging complications to treat. Hereby, the effects of the scaffold derived from the human demineralized bone matrix (hDBMS) plus human adipose stem cells (hADSs) plus photobiomodulation (PBM) (in vitro and or in vivo) on the catabolic step of femoral bone repair in rats with critical size femoral defects (CDFDs) were evaluated with stereology and high stress load (HSL) assessment methods. Methods: hADSs were exposed to PBM in vitro; then, the mixed influences of hDBMS+hADS+PBM on CSFDs were evaluated. CSFDs were made on both femurs; then hDBMSs were engrafted into both CSFDs of all rats. There were 6 groups (G)s: G1 was the control; in G2 (hADS), hADSs only were engrafted into hDBMS of CSFD; in G3 (PBM) only PBM therapy for CSFD was provided; in G4 (hADS+PBM in vivo), seeded hADSs on hDBMS of CSFDs were radiated with a laser in vivo; in G5 (hADSs+PBM under in vitro condition), hADSs in a culture system were radiated with a laser, then transferred on hDBMS of CSFDs; and in G6 (hADS+PBM in conditions of in vivo and in vitro), laser-exposed hADSs were transplanted on hDBMS of CSFDs, and then CSFDs were exposed to a laser in vivo. Results: Groups 4, 5, and 6 meaningfully improved HSLs of CSFD in comparison with groups 3, 1, and 2 (all, P=0.001). HSL of G5 was significantly more than G4 and G6 (both, P=0.000). Gs 6 and 4 significantly increased new bone volumes of CSFD compared to Gs 2 (all, P=0.000) and 1 (P=0.001 & P=0.003 respectively). HSL of G 1 was significantly lower than G5 (P=0.026). Conclusion: HSLs of CSFD in rats that received treatments of hDBMS plus hADS plus PBM were significantly higher than treatments with hADS and PBM alone and control groups.

Evaluation of the effects of preconditioned human stem cells plus a scaffold and photobiomodulation administration on stereological parameters and gene expression levels in a critical size bone defect in rats

We assessed the impact of photobiomodulation (PBM) plus adipose-derived stem cells (ASCs) during the anabolic and catabolic stages of bone healing in a rat model of a critical size femoral defect (CSFD) that was filled with a decellularized bone matrix (DBM). Stereological analysis and gene expression levels of bone morphogenetic protein 4 (BMP4), Runt-related transcription factor 2 (RUNX2), and stromal cell-derived factor 1 (SDF1) were determined. There were six groups of rats. Group 1 was the untreated control or DBM. Study groups 2-6 were treated as follows: ASC (ASC transplanted into DBM, then implanted in the CSFD); PBM (CSFD treated with PBM); irradiated ASC (iASC) (ASCs preconditioned with PBM, then transplanted into DBM, and implanted in the CSFD); ASC + PBM (ASCs transplanted into DBM, then implanted in the CSFD, followed by PBM administration); and iASC + PBM (the same as iASC, except CSFDs were exposed to PBM). At the anabolic step, all treatment groups had significantly increased trabecular bone volume (TBV) (24.22%) and osteoblasts (83.2%) compared to the control group (all, p = .000). However, TBV in group iASC + PBM groups were superior to the other groups (97.48% for osteoblast and 58.8% for trabecular bone volume) (all, p = .000). The numbers of osteocytes in ASC (78.2%) and iASC + PBM (30%) groups were remarkably higher compared to group control (both, p = .000). There were significantly higher SDF (1.5-fold), RUNX2 (1.3-fold), and BMP4 (1.9-fold) mRNA levels in the iASC + PBM group compared to the control and some of the treatment groups. At the catabolic step of bone healing, TBV increased significantly in PBM (30.77%), ASC + PBM (32.27%), and iASC + PBM (35.93%) groups compared to the control group (all, p = .000). There were significantly more osteoblasts and osteocytes in ASC (71.7%, 62.02%) (p = .002, p = .000); PBM (82.54%, 156%), iASC (179%, 23%), and ASC + PBM (108%, 110%) (all, p = .000), and iASC + PBM (79%, 100.6%) (p = .001, p = .000) groups compared to control group. ASC preconditioned with PBM in vitro plus PBM in vivo significantly increased stereological parameters and SDF1, RUNX2, and BMP4 mRNA expressions during bone healing in a CSFD model in rats.

Cell and Cell Free Therapies in Osteoarthritis

Osteoarthritis (OA) is the most common articular disease in adults and has a current prevalence of 12% in the population over 65 years old. This chronic disease causes damage to articular cartilage and synovial joints, causing pain and leading to a negative impact on patients' function, decreasing quality of life. There are many limitations regarding OA conventional therapies-pharmacological therapy can cause gastrointestinal, renal, and cardiac adverse effects, and some of them could even be a threat to life. On the other hand, surgical options, such as microfracture, have been used for the last 20 years, but hyaline cartilage has a limited regeneration capacity. In recent years, the interest in new therapies, such as cell-based and cell-free therapies, has been considerably increasing. The purpose of this review is to describe and compare bioregenerative therapies' efficacy for OA, with particular emphasis on the use of mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP). In OA, these therapies might be an alternative and less invasive treatment than surgery, and a more effective option than conventional therapies.

Comparison of Individual Tissue-Engineered Bones and Allogeneic Bone in Treating Bone Defects: A Long-Term Follow-Up Study

The treatment of bone defects has always been a challenge for orthopedic surgeons. The development of tissue engineering technology provides a novel method for repairing bone defects and has been used in animal experiments and clinical trials. However, there are few clinical studies on comparing the long-term outcomes of tissue-engineered bones (TEBs) and other bone grafts in treating bone defects, and the long-term efficiency of TEBs remains controversial. Therefore, a study designed by us was aimed to compare the long-term efficacy and safety of individual tissue-engineered bones (iTEBs) and allogeneic bone granules (ABGs) in treating bone defects caused by curettage of benign bone tumors and tumor-like lesions. From September 2003 to November 2009, 48 patients who received tumor curettage and bone grafting were analyzed with a mean follow-up of 122 mo (range 60 to 173 mo). Based on implant style, patients were divided into groups of iTEBs (n = 23) and ABGs (n = 25). Postoperatively, the healing time, healing quality, incidence of complications, and functional scores were compared between the two groups. The Musculoskeletal Tumor Society functional evaluation system and Activities of Daily Living Scale scores were significantly improved in both groups with no significant difference. The average healing time of ABGs was longer than that of iTEBs (P < 0.05). At the final follow-up, iTEBs had a better performance in the bone healing quality evaluated by modified Neer classification (P < 0.05). In the group of iTEBs, the complication and reoperation rate was lower than that in the group of ABGs, with no tumorigenesis or immune rejection observed. In summary, for treating bone defects caused by tumor curettage, iTEBs were safe, effective, and tagged with more rapid healing speed, better healing outcome, and lower complication and reoperation rate, in comparison with ABGs.

Small Ruminants and Its Use in Regenerative Medicine: Recent Works and Future Perspectives

Simple Summary

Small ruminants such as sheep and goats have been increasingly used as animal models due to their dimensions, physiology and anatomy identical to those of humans. Their low costs, ease of accommodation, great longevity and easy handling make them advantageous animals to be used in a wide range of research work. Although there is already a lot of scientific literature describing these species, their use still lacks some standardization. The purpose of this review is to summarize the general principles related to the use of small ruminants as animal models for scientific research.

Abstract

Medical and translational scientific research requires the use of animal models as an initial approach to the study of new therapies and treatments, but when the objective is an exploration of translational potentialities, classical models fail to adequately mimic problems in humans. Among the larger animal models that have been explored more intensely in recent decades, small ruminants, namely sheep and goats, have emerged as excellent options. The main advantages associated to the use of these animals in research works are related to their anatomy and dimensions, larger than conventional laboratory animals, but very similar to those of humans in most physiological systems, in addition to their low maintenance and feeding costs, tendency to be docile, long life expectancies and few ethical complications raised in society. The most obvious disadvantages are the significant differences in some systems such as the gastrointestinal, and the reduced amount of data that limits the comparison between works and the validation of the characterization essays. Despite everything, recently these species have been increasingly used as animal models for diseases in different systems, and the results obtained open doors for their more frequent and advantageous use in the future. The purpose of this review is to summarize the general principles related to the use of small ruminants as animal models, with a focus on regenerative medicine, to group the most relevant works and results published recently and to highlight the potentials for the near future in medical research.

Recent Advances in Biomaterials for the Treatment of Bone Defects

Bone defects or fractures generally heal in the absence of major interventions due to the high regenerative capacity of bone tissue. However, in situations of severe/large bone defects, these orchestrated regeneration mechanisms are impaired. With advances in modern medicine, natural and synthetic bio-scaffolds from bioceramics and polymers that support bone growth have emerged and gained intense research interest. In particular, scaffolds that recapitulate the molecular cues of extracellular signals, particularly growth factors, offer potential as therapeutic bone biomaterials. The current challenges for these therapies include the ability to engineer materials that mimic the biological and mechanical properties of the real bone tissue matrix, whilst simultaneously supporting bone vascularization. In this review, we discuss the very recent innovative strategies in bone biomaterial technology, including those of endogenous biomaterials and cell/drug delivery systems that promote bone regeneration. We present our understanding of their current value and efficacy, and the future perspectives for bone regenerative medicine.

Preconditioning adipose-derived stem cells with photobiomodulation significantly increased bone healing in a critical size femoral defect in rats

We assessed the combined impacts of human demineralized bone matrix (hDBM) scaffold, adipose-derived stem cells (hADS), and photobiomodulation (PBM) on bone repair of a critical size femoral defect (CSFD) in 72 rats. The rats were divided into six groups: control (group 1); ADS (group 2 - ADS transplanted into hDBM); PBM (group 3 - PBM-treated CSFDs); ADS + PBM in vivo (group 4 - ADS transplanted into hDBM and the CSFDs were treated with PBM in vivo); ADS + PBM in vitro (group 5 - ADS were treated with PBM in vitro, then seeded into hDBM); and ADS + PBM in vitro+in vivo (group 6 - PBM-treated ADS were seeded into hDBM, and the CSFDs were treated with PBM in vivo. At the anabolic phase (2 weeks after surgery), bone strength parameters of the groups 5, 6, and 4 were statistically greater than the control, ADS, and PBM in vivo groups (all, p = 0.000). Computed tomography (CT) scans during the catabolic phase (6 weeks after surgery) of bone healing revealed that the Hounsfield unit (HU) of CSFD in the groups 2 (p = 0.000) and 5 (p = 0.019) groups were statistically greater than the control group. The groups 5, 4, and 6 had significantly increased bone strength parameters compared with the PBM in vivo, control, and ADS groups (all, p = 0.000). The group 5 was statistically better than the groups 4, and 6 (both, p = 0.000). In vitro preconditioned of hADS with PBM significantly increased bone repair in a rat model of CSFD in vivo.

Allogenic Bone Graft Enriched by Periosteal Stem Cell and Growth Factors for Osteogenesis in Critical Size Bone Defect in Rabbit Model: Histopathological and Radiological Evaluation

Background & Objective:

This study aimed to investigate the effect of decellularized allogeneic bone graft enriched by periosteal stem cells (PSCs) and growth factors on the bone repair process in a rabbit model, which could be used in many orthopedic procedures.

Methods:

In this experimental study, a critical size defect (CSD) (10 mm) was created in the radial diaphysis of 40 rabbits. In group A, the defect was left intact with no medical intervention. In group B, the defect was filled by a decellularized bone graft. In group C, the defect was implanted by a decellularized bone graft enriched with platelet growth factors. In group D, the defect was treated by a decellularized bone graft seeded by periosteal mesenchymal stem cells (MSCs). Also, in group E, the defect was filled by a decellularized bone graft enriched with platelet growth factors and periosteal MSCs. Radiological evaluation was done on the first day and then in the second, fourth, and eighth weeks after the operation. The specimens were harvested on the 28th and 56th postoperative days and evaluated for histopathological criteria.

Results:

The radiologic and microscopic analysis of the healing process in bone defects of the treated groups (C, D, and E) revealed more advanced repair criteria than those of groups A and B significantly (P<0.05).

Conclusion:

Based on this study, it appears that implantation of concentrated PSCs in combination with growth factors and allogeneic cortical bone graft is an effective therapy for the repair of large bone defects.

Exosomal miRNA-128-3p from mesenchymal stem cells of aged rats regulates osteogenesis and bone fracture healing by targeting Smad5

Transplantation of mesenchymal stem cells (MSCs) has been considered an effective therapeutic treatment for a variety of diseases including bone fracture. However, there are associated complications along with MSCs transplantation. There is evidence to show that exosomes (Exos) derived from MSCs exert a similar paracrine function. In addition, repair capabilities of MSCs decline with age. Hence, this study aims to confirm whether the Exos protective function on osteogenic differentiation and fracture healing from aged MSCs was attenuated. This information was used in order to investigate the underlying mechanism. MSCs were successfully isolated and identified from young and aged rats, and Exos were then obtained. Aged-Exos exhibited significantly attenuated effects on MSCs osteogenic differentiation in vitro and facture healing in vivo. Using miRNA array analysis, it was shown that miR-128-3p was markedly upregulated in Aged-Exos. In vitro experiments confirmed that Smad5 is a direct downstream target of miR-128-3p, and was inhibited by overexpressed miR-128-3p. A series gain- and loss- function experiment indicated that miR-128-3P serves a suppressor role in the process of fracture healing. Furthermore, effects caused by miR-128-3P mimic/inhibitor were reversed by the application of Smad5/siSmad5. Taken together, these results suggest that the therapeutic effects of MSCs-derived Exos may vary according to differential expression of miRNAs. Exosomal miR-128-3P antagomir may act as a promising therapeutic strategy for bone fracture healing, especially for the elderly.

Subtalar Arthrodesis with Use of Adipose-Derived Cellular Bone Matrix Compared with Autologous Bone Graft: A Multicenter, Randomized Controlled Trial

UPDATE

This article was updated on November 7, 2019, because of a previous error. On page 1909, in the section entitled "Discussion," the sentence that had read "Radiographic nonunion rates of 69.2% and 45.6% were observed at 6 months for ACBM and autograft, respectively, as measured on CT scans; however, these nonunion rates do account for patients who were considered to have attained fusion according to traditional methods, including absence of pain and swelling and presence of arthrodesis on radiographs" now reads "Radiographic nonunion rates of 69.2% and 45.6% were observed at 6 months for ACBM and autograft, respectively, as measured on CT scans; however, these nonunion rates do not account for patients who were considered to have attained fusion according to traditional methods, including absence of pain and swelling and presence of arthrodesis on radiographs."An erratum has been published: J Bone Joint Surg Am. 2019 XXX.

BACKGROUND

Subtalar arthrodesis effectively treats subtalar joint arthritis when other interventions have failed. Nonunion is a known complication of subtalar arthrodesis, with reported rates ranging from 5% to 45%. Historically, open arthrodesis has been performed with use of autologous bone graft; however, there are inherent disadvantages to autologous bone graft, including donor-site morbidity. Mesenchymal stem cells, when placed on a cellular scaffold, have shown promise as an alternative to autologous bone graft. The purpose of this multicenter, randomized controlled trial was to assess the safety and efficacy of an adipose-derived cellular bone matrix (ACBM) composite made with live cells compared with autograft in subtalar arthrodesis.

METHODS

A total of 140 patients were enrolled in a prospective, randomized (1:1) controlled trial performed at 6 clinical sites in the U.S. End points, including radiographic, clinical, and functional outcomes, were assessed over 2 years of follow-up.

RESULTS

A total of 109 patients underwent arthrodesis with ACBM (52 patients) and autograft (57 patients). At 6 months, fusion was achieved in 16 patients (30.8%) in the ACBM group and 31 patients (54.4%) in the autograft group as measured on computed tomography (p = 0.024), and in 41 patients (78.8%) in the ACBM group and 50 patients (87.7%) in the autograft group as assessed on clinical and radiographic evaluation (p = 0.213). Quality-of-life outcome measures demonstrated significant functional improvement from baseline for both groups. Fewer cases of serious adverse events occurred in the autograft group (10.5%) compared with the ACBM group (23.1%) (p = 0.078).

CONCLUSIONS

In patients who require subtalar arthrodesis, the use of ACBM demonstrated lower rates of radiographic fusion compared with treatment with autograft. The nonunion rate in the autologous group, as measured on computed tomography, was high. Good clinical outcomes were achieved in spite of the high non-union rates.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Adipose-Derived Mesenchymal Stem Cells: A Promising Tool in the Treatment of Musculoskeletal Diseases

Chronic musculoskeletal (MSK) pain is one of the most common medical complaints worldwide and musculoskeletal injuries have an enormous social and economical impact. Current pharmacological and surgical treatments aim to relief pain and restore function; however, unsatiscactory outcomes are commonly reported. In order to find an accurate treatment to such pathologies, over the last years, there has been a significantly increasing interest in cellular therapies, such as adipose-derived mesenchymal stem cells (AMSCs). These cells represent a relatively new strategy in regenerative medicine, with many potential applications, especially regarding MSK disorders, and preclinical and clinical studies have demonstrated their efficacy in muscle, tendon, bone and cartilage regeneration. Nevertheless, several worries about their safety and side effects at long-term remain unsolved. This article aims to review the current state of AMSCs therapy in the treatment of several MSK diseases and their clinical applications in veterinary and human medicine.

Bergenin Activates SIRT1 as a Novel Therapeutic Agent for Osteogenesis of Bone Mesenchymal Stem Cells

Bone mesenchymal stem cells (BMSCs) are important candidates for bone regeneration. The role of Bergenin, a C-glucoside of 4-O-methyl gallic acid obtained from the species, Bergenia, in BMSC osteogenesis has not yet been elucidated. We therefore investigated the effects of Bergenin on the osteogenesis of BMSCs and found that Bergenin enhanced osteoblast-specific markers and downregulated the adipocyte-specific markers in vitro. Furthermore, using a rat calvarial defect model, we found that Bergenin significantly improved bone healing, as determined by imaging and histological analyses. Moreover, it also upregulated SIRT1 expression. A SIRT1 inhibitor (EX 527) decreased the enhanced bone mineral formation caused by Bergenin. Taken together, these findings show that Bergenin accelerated the osteogenic differentiation of BMSCs, at least partly through the activation of SIRT1.

Innovative Biomaterials for Bone Regrowth

The regenerative medicine, a new discipline that merges biological sciences and the fundamental of engineering to develop biological substitutes, has greatly benefited from recent advances in the material engineering and the role of stem cells in tissue regeneration. Regenerative medicine strategies, involving the combination of biomaterials/scaffolds, cells, and bioactive agents, have been of great interest especially for the repair of damaged bone and bone regrowth. In the last few years, the life expectancy of our population has progressively increased. Aging has highlighted the need for intervention on human bone with biocompatible materials that show high performance for the regeneration of the bone, efficiently and in a short time. In this review, the different aspects of tissue engineering applied to bone engineering were taken into consideration. The first part of this review introduces the bone cellular biology/molecular genetics. Data on biomaterials, stem cells, and specific growth factors for the bone regrowth are reported in this review.