FGF2: a key regulator augmenting tendon-to-bone healing and cartilage repair

Arctiin attenuated NASH by inhibiting glycolysis and inflammation via FGFR2/CSF1R signaling

The present work was conducted to evaluate the pharmacological effect of Arctiin(ARC) on high fat diet(HFD)-induced Non-alcoholic steatohepatitis(NASH) and investigate its potential mechanism. The network pharmacology and bioinformatic analyses predicted that FGFR2 might be the potential target of ARC. Palmitic acid(PA)-induced AML12 cell was employed as the in vitro model. ARC reduced the levels of ALT, AST, TC, TG, and attenuated histopathological alteration. ARC inhibited inflammatory cytokines, inflammatory molecules, downregulated the expressions of FGFR2/CSF1R, inhibited glycolysis and promoted oxidative phosphorylation both in vivo and in vitro. ARC enhanced mitochondrial membrane potential and reduced oxidative stress. The application of FGFR2-OE plasmid, CSF1R-OE plasmid, CSF1R inhibitor PLX indicated that ARC attenuated glycolysis and inflammation in PA-induced AML12 cells via FGFR2/CSF1R signaling. HIF1A was proved to be involved in this process using HIF1A agonist DEF and HIF1A inhibitor PX478. Molecular docking and molecular dynamic suggested that ARC might combine with FGFR2. In conclusion, the present study demonstrated that ARC ameliorated NASH by inhibiting glycolysis and inflammation via FGFR2/CSF1R signaling.

Myricetin promotes migration and prevents palmitate-induced apoptosis in cultured tenocytes through AMPK-dependent pathways

Myricetin (Myr), a flavonoid present in vegetables and fruits, has been shown to ameliorate inflammation and oxidative stress in various disease models. However, the effects of Myr on hyperlipidemic tenocytes have not been studied. Herein, we aimed to investigate the effects of Myr on the features of tendinopathy in cultured tenocytes under hyperlipidemic conditions. Reactive oxygen species (ROS) were detected by DCFDA. Hydrogen peroxide (H2O2), malondialdehyde (MDA), and caspase 3 activity were quantified via matched assay kits. Apoptotic cells were detected via TUNEL staining. Proteins investigated in this study were evaluated through Western blotting. Treatment with Myr enhanced tenocyte migration and prevented apoptosis, inflammation and oxidative stress in palmitate-treated tenocytes. Myr treatment increased the phosphorylation of AMPK, and the expression of PGC1α and FGF2. siRNA targeting AMPK abrogated the effects of Myr on palmitate-treated tenocytes. However, FGF2 siRNA reduced the impacts of Myr on only cell migration and ECM signaling. These in vitro results suggest that Myr promotes tenocyte migration and ECM signaling via AMPK/FGF2 signaling and attenuates apoptosis through the AMPK-mediated suppression of inflammation and oxidative stress in hyperlipidemic tenocytes. This study sheds light on therapeutic strategies for treating obesity-related tendinopathy.

Hypoxia-regulated miR-103-3p/FGF2 axis in adipose-derived stem cells promotes angiogenesis by vascular endothelial cells during ischemic tissue repair

BACKGROUND

Identifying factors mediating adipose-derived stem cells (ADSCs)-induced endothelial cell angiogenesis in hypoxic skin flap tissue is critical for reconstruction. While the paracrine action of VEGF by adipose-derived stem cells (ADSCs) is established in promoting endothelial cell angiogenesis, the role of FGF2 and its regulatory mechanisms in ADSCs paracrine secretion remains unclear.

METHODS

We induced hypoxia and examined the expression level of FGF2 in ADSCs using ELISA, qRT-PCR, and western blotting. Proliferation of ADSCs under hypoxia was assessed using a CCK-8 assay. Co-culture experiments of hypoxia-induced ADSCs with vascular endothelial cells were conducted, and migration and tube formation abilities were evaluated through wound healing assays, transwell cell migration, and tube formation experiments.

RESULTS

Hypoxia treatment induced significant upregulation of FGF2 expression in ADSCs, along with enhanced cell proliferation. Co-culture of hypoxia-induced ADSCs with vascular endothelial cells showed increased migration and tube formation abilities of endothelial cells. Knockdown of FGF2 inhibited these processes, while overexpression of miR-103-3p mimics in ADSCs suppressed endothelial cell migration and tube formation. FGF2 is a direct target of miR-103-3p in ADSCs. miR-103-3p/FGF2 axis regulates ADSCs on the biological activity of co-cultured vascular endothelial cells. Moreover, in the ischemic skin flap nude mouse model, ADSCs injection showed increased blood vessel formation and reduced flap necrosis, with the most significant improvement observed with ADSCs of miR-103-3p inhibitor overexpressed.

CONCLUSION

Hypoxia induces paracrine secretion of FGF2 from ADSCs, which enhances endothelial cell angiogenesis. FGF2 expression is regulated by miR-103-3p in ADSCs. The miR-103-3p/FGF2 axis induces endothelial cell migration and angiogenesis and finally modulates ischemic skin flap repair in nude mice in vivo.

Engineered protein-based materials for tissue repair: A review

The human body may suffer multiple injuries and losses due to various external factors, such as tumors, diseases, traffic accidents, and war conflicts. Under such circumstances, engineered protein-based materials, as an innovative adjunctive material, can not only effectively promote the natural repair process of tissues, but also greatly circumvent the negative effects and complications that may be associated with conventional surgery. In this review, we first trace the definition and development of engineered protein-based materials and explain in detail their mechanism of action in promoting tissue repair. Subsequently, the advantages and disadvantages of various engineered protein-based materials in tissue repair are analyzed by comparison. In addition, the present review reveals in depth how material properties can be optimized by scientific means to meet different tissue repair needs. In addition, we present in detail specific application cases of engineered protein-based materials in the field of tissue repair. Finally, we summarize current challenges in engineered protein-based materials and provide an outlook for the future. This review not only provides theoretical support for the further exploration and development of engineered protein-based materials in the field of tissue repair, but also provides valuable references and inspiration for research in related fields.

Conditioned medium of engineering macrophages combined with soluble microneedles promote diabetic wound healing

Diabetic wounds have a profound effect on both the physical and psychological health of patients, highlighting the urgent necessity for novel treatment strategies and materials. Macrophages are vital contributors to tissue repair mechanisms. Macrophage conditioned medium contains various proteins and cytokines related to wound healing, indicating its potential to improve recovery from diabetic wound. Engineering macrophages may enable a further improvement in their tissue repair capacity. Fibroblast growth factor 2 (FGF2) is a crucial growth factor that plays an integral role in wound healing process. And in this study, a stable macrophage cell line (engineered macrophages) overexpressing FGF2 was successfully established by engineering modification of macrophages. Proteomic analysis indicated that conditioned medium derived from FGF2 overexpressed macrophages may promote wound healing by enhancing the level of vascularization. Additionally, cellular assays demonstrated that this conditioned medium promotes endothelial cell migration in vitro. For the convenience of drug delivery and wound application, we prepared soluble hyaluronic acid microneedles to load the conditioned medium. These soluble microneedles exhibited excellent mechanical properties and biocompatibility while effectively releasing their contents in vivo. The microneedles significantly accelerated wound healing, leading to a marked increase in vascular proliferation and improved collagen deposition within a full thickness skin defect diabetic mouse model. In summary, we developed a type of hyaluronic acid microneedle loaded with conditioned medium of engineered macrophages. These microneedles have been demonstrated to enhance tissue vascularization and facilitate diabetic wound healing. This might potentially serve as a highly promising therapeutic approach for diabetic wounds.

Exerkines: Potential regulators of ferroptosis

Ferroptosis is a programmed cell death, and its mechanism involves multiple metabolic pathways, such as iron and lipid metabolism, and redox homeostasis. Exerkines are important mediators that optimize cellular homeostasis and maintain physiological health during exercise stimulation. This article comprehensively examines the mechanisms and regulatory networks for governing ferroptosis and summarizes the impact of exercise and exerkines on ferroptosis under varying load intensities and disease contexts. Notably, despite its significant efficacy and minimal side effects, the therapeutic and prognostic potential of exercise in ferroptosis-related diseases remains largely unexplored. This article, by summarizing recent progresses in the regulation of exerkines-mediated ferroptosis, could further uncover the preventive or alleviative mechanisms of some diseases upon exercise interventions, which will be beneficial to design exercise interventional strategies for alleviating disease progression through the regulation of ferroptosis.

Autophagy modulates tenogenic differentiation of cartilage-derived stem cells in response to mechanical tension via FGF signaling

BACKGROUND

In our previous study, we demonstrated that cartilage-derived stem cells (CDSCs) possess multi-differentiation potential, enabling direct bone-to-tendon structure regeneration after transplantation in a rat model. Therefore, the objective of this study is to investigate whether CDSCs are a suitable candidate for achieving biological regeneration of tendon injuries.

METHODS

Tenogenic differentiation was evaluated through cell morphology observation, PCR, and Western blot (WB) analysis. Autophagic flux, transmission electron microscopy, and WB analysis were employed to elucidate the role of autophagy during CDSC tenogenic differentiation. Cell survival and tenogenesis of transplanted CDSCs were assessed using fluorescence detection of gross and frozen section images. Heterotopic ossification and quality of tendon healing were evaluated by immunofluorescence, hematoxylin-eosin (H&E), and Safrinin O/Fast Green stains.

RESULTS

We found autophagy is activated in CDSCs when treated with cyclic tensile stress, which facilitates the preservation of their chondrogenic potential while impeding tenogenic differentiation. Inhibiting autophagy with chloroquine promoted tenogenic differentiation of CDSCs in response to cyclic tensile stress through activation of the Fgf2/Fgfr2 signaling pathway. This mechanism was further validated by 2 mouse transplantation models, revealed that autophagy inhibition could enhance the tendon regeneration efficacy of transplanted CDSCs at the patellar tendon resection site.

CONCLUSION

Our findings provide insights into CDSC transplantation for achieving biological regeneration of tendon injuries, and demonstrate how modulation of autophagy in CDSCs can promote tenogenic differentiation in response to tensile stress both in vivo and in vitro.

Mesenchymal Stem Cell Extract Promotes Skin Wound Healing

Recently, it has been reported that mesenchymal stem cell (MSC)-derived humoral factors promote skin wound healing. As these humoral factors are transiently stored in cytoplasm, we collected them as part of the cell extracts from MSCs (MSC-ext). This study aimed to investigate the effects of MSC-ext on skin wound healing. We examined the effects of MSC-ext on cell proliferation and migration. Additionally, the effect of MSC-ext on skin wound healing was evaluated using a mouse skin defect model. The MSC-ext enhanced the proliferation of dermal fibroblasts, epithelial cells, and endothelial cells. It also increased the number of migrating fibroblasts and epithelial cells. The skin defects treated with MSC-ext demonstrated rapid wound closure compared to those treated with phosphate-buffered saline. The MSC-ext group exhibited a thicker dermis, larger Picrosirius red-positive areas, and a higher number of Ki67-positive cells. Our results indicate that MSC-ext promotes the proliferation and/or migration of fibroblasts, epithelial cells, and endothelial cells, and enhances skin wound healing. This suggests the therapeutic potential of MSC-ext in treating skin defects as a novel cell-free treatment modality.

Decoding FGF/FGFR Signaling: Insights into Biological Functions and Disease Relevance

Fibroblast Growth Factors (FGFs) and their cognate receptors, FGFRs, play pivotal roles in a plethora of biological processes, including cell proliferation, differentiation, tissue repair, and metabolic homeostasis. This review provides a comprehensive overview of FGF-FGFR signaling pathways while highlighting their complex regulatory mechanisms and interconnections with other signaling networks. Further, we briefly discuss the FGFs involvement in developmental, metabolic, and housekeeping functions. By complementing current knowledge and emerging research, this review aims to enhance the understanding of FGF-FGFR-mediated signaling and its implications for health and disease, which will be crucial for therapeutic development against FGF-related pathological conditions.

Recent Strategies and Advances in Hydrogel-Based Delivery Platforms for Bone Regeneration

Bioactive molecules have shown great promise for effectively regulating various bone formation processes, rendering them attractive therapeutics for bone regeneration. However, the widespread application of bioactive molecules is limited by their low accumulation and short half-lives in vivo. Hydrogels have emerged as ideal carriers to address these challenges, offering the potential to prolong retention times at lesion sites, extend half-lives in vivo and mitigate side effects, avoid burst release, and promote adsorption under physiological conditions. This review systematically summarizes the recent advances in the development of bioactive molecule-loaded hydrogels for bone regeneration, encompassing applications in cranial defect repair, femoral defect repair, periodontal bone regeneration, and bone regeneration with underlying diseases. Additionally, this review discusses the current strategies aimed at improving the release profiles of bioactive molecules through stimuli-responsive delivery, carrier-assisted delivery, and sequential delivery. Finally, this review elucidates the existing challenges and future directions of hydrogel encapsulated bioactive molecules in the field of bone regeneration.

Orthopedic revolution: The emerging role of nanotechnology

This review summarizes the latest progress in orthopedic nanotechnology, explores innovative applications of nanofibers in tendon repair, and evaluates the potential of selenium and cerium oxide nanoparticles in osteoarthritis and osteoblast differentiation. This review also describes the emerging applications of injectable hydrogels in cartilage engineering, emphasizing the critical role of interdisciplinary research and highlighting the challenges and future prospects of integrating nanotechnology into orthopedic clinical practice. This comprehensive approach provides a holistic perspective on the transformative impact of nanotechnology in orthopedics, offering valuable insights for future research and clinical applications.

FGF-2 enriched nanofiber scaffold for advancing achilles tendon healing: a comparative experimental investigation

Introduction

Achilles tendon rupture is a common and debilitating injury that significantly impacts mobility and quality of life. Effective treatment options that promote faster and more complete healing are needed. Fibroblast growth factor-2 (FGF-2) has shown potential in enhancing tendon repair. This study aims to investigate the efficacy of FGF-2 in promoting tendon healing in a rat model of Achilles tendon rupture, providing insights into its potential as a therapeutic option.

Materials and methods

Forty-eight rat hind legs with complete Achilles tendon ruptures were divided into four equal groups: the Sham (S) group (tendon repair only), the Polymer (P) group (tendon repair with scaffold wrapping), the Produced FGF-2 (PF) group (scaffold coated with lab-produced FGF-2), and the Commercial FGF-2 (CF) group (scaffold coated with commercially sourced FGF-2). Histological analyses at two and four weeks post-surgery evaluated healing based on nuclear morphology, vascularity, fibril organization, inflammation, and adipogenesis.

Results

At the end of the second week, no macroscopic healing was observed in one rat each from the S and P groups. By the end of the fourth week, macroscopic healing was observed in all groups. The S and P groups exhibited similarly severe fibril disorganization, pathological adipogenesis, and sustained inflammation, particularly at the fourth week. In contrast, the CF group demonstrated improved tendon healing with increased vascularity and extracellular matrix, lower inflammatory cell infiltration, and better fibril organization. Pathological adipogenesis was absent in the CF group, especially at the fourth week. The PF group showed comparable improvements at the second week but experienced a relapse by the 4th week, with increased inflammation and adipogenesis.

Conclusion

FGF-2 coated scaffolds significantly enhanced tendon healing in a rat Achilles tendon rupture model by improving fibril organization, increasing vascularity, and reducing inflammation and pathological adipogenesis. These findings suggest that FGF-2 could be a promising therapeutic option for accelerating tendon repair. Future perspectives on tendon repair will focus on enhancing FGF-2 delivery using innovative scaffolds, paving the way for more effective therapies and improved patient outcomes.

miR-16a-5p antagonizes FGF-2 in ligamentogenic differentiation of MSC: a new therapeutic perspective for tendon regeneration

With the increasing demand for exercise, the population of patients with ankle sprain to anterior talofibular ligament injury has the characteristics of a large base and high requirements for returning to sports, and how to promote the repair of damaged ligaments from a microscopic perspective is an urgent problem to be solved. In many studies, human amniotic mesenchymal stem cells have strong differentiation ability, and can be induced to continuously differentiate into ligament cells to achieve the purpose of repairing damaged ligaments. Human amniotic stem cells were extracted and cultured from human amniotic tissues, evaluated by cell identification and other techniques, and evaluated into ligament differentiation by toluidine blue, alizarin red, oil red O staining and detection of ligament cell differentiation, protein detection by Western blot, mRNA level by qPCR, and finally, the targeted binding relationship between miR-16a-5p and mRNA FGF2 was verified by double luciferase reporter assay. The expression of collagen type 1 (COL 1), collagen type 3 (COL3), SCX and MKX was increased by overexpression of mRNA FGF2, respectively, and miR-16a-5p had a targeted effect on FGF2 and regulated the ligamentous differentiation of human amniotic mesenchymal stem cells. We found that the regulatory effect of overexpressed mRNA FGF2 on mesenchymal stem cells could be inhibited by up-regulation of miR-16a-5p, while the knockdown of FGF2 could reverse the regulatory effect of miR-16a-5p inhibition on ligament-forming differentiation of human amniotic mesenchymal stem cells. In this study, we discovered the existence of the miR-16a-5p-FGF2 axis in human amniotic mesenchymal stem cells, and the differentiation of human amniotic mesenchymal stem cells into ligamentous cells can be regulated by regulating various links in this axis.

Proteomic Characterization of Human Placenta: Insights into Potential Therapeutic Applications for Osteoarthritis

Biologics have become increasingly prominent as therapeutics in recent years due to their innate immune-privileged nature, biocompatibility, and high levels of protein biofactors. The aim of the study is to characterise the biologic, lyophilized human placenta (LHP) and explore its therapeutic potential for osteoarthritis (OA). The presence of six bioactive constituents that regulate cell-extracellular matrix interaction was identified by liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF/MS). Metalloproteinase inhibitor 3 (TIMP3), alpha-1 anti-trypsin (a1AT), basic fibroblast growth factor (bFGF), and transforming growth factor β1 (TGFβ1) were detected and quantified using ELISA. The total protein content present in LHP by Bradford assay was found to be 409.35 ± 0.005 μg/ml. The analytical techniques such as Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR), solid state carbon-13 Nuclear Magnetic Resonance (ssC13 NMR) spectroscopy, and Differential Scanning Calorimetry (DSC) revealed the secondary structure and conformational stability of LHP. X-Ray diffraction (XRD) studies showed its amorphous nature. Bioactivity assessment of LHP was performed in human keratinocytes (HaCaT) and human dermal fibroblasts (HDF) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The LHP was highly proliferative against skin cells and non-toxic, based on the findings of the bioactivity assay. LHP has the potential to be used as a therapeutic agent for OA, as its characterisation unveiled its physical stability, significant concentration of bioactive components that are pertinent to cartilage repair and its conformational stability.

Single-cell RNA landscape of osteoimmune microenvironment in osteoporotic vertebral compression fracture and Kümmell's disease

Background: Single-cell RNA sequencing (scRNA-seq) enables specific analysis of cell populations at single-cell resolution; however, there is still a lack of single-cell-level studies to characterize the dynamic and complex interactions between osteoporotic vertebral compression fractures (OVCFs) and Kümmell's disease (KD) in the osteoimmune microenvironment. In this study, we used scRNA-seq analysis to investigate the osteoimmune microenvironment and cellular composition in OVCFs and KD. Methods: ScRNA-seq was used to perform analysis of fractured vertebral bone tissues from one OVCF and one KD patients, and a total of 8,741 single cells were captured for single-cell transcriptomic analysis. The cellularity of human vertebral bone tissue was further analyzed using uniform manifold approximation and projection. Pseudo-time analysis and gene enrichment analysis revealed the biological function of cell fate and its counterparts. CellphoneDB was used to identify the interactions between bone cells and immune cells in the osteoimmune microenvironment of human vertebral bone tissue and their potential functions. Results: A cellular profile of the osteoimmune microenvironment of human vertebral bone tissue was established, including mesenchymal stem cells (MSCs), pericytes, myofibroblasts, fibroblasts, chondrocytes, endothelial cells (ECs), granulocytes, monocytes, T cells, B cells, plasma cells, mast cells, and early erythrocytes. MSCs play an immunoregulatory function and mediate osteogenic differentiation and cell proliferation. The differentiation trajectory of osteoclasts in human vertebral bone tissue was also revealed. In addition, ECs actively participate in inflammatory infiltration and coupling with bone cells. T and B cells actively participate in regulating bone homeostasis. Finally, by identifying the interaction of ligand-receptor pairs, we found that immune cells and osteoclasts have bidirectional regulatory characteristics, have the effects of regulating bone resorption by osteoclasts and promoting bone formation, and are essential for bone homeostasis. It is also highlighted that CD8-TEM cells and osteoclasts might crosstalk via CD160-TNFRSF14 ligand-receptor interaction. Conclusion: Our analysis reveals a differential landscape of molecular pathways, population composition, and cell-cell interactions during OVCF development into KD. OVCFs exhibit a higher osteogenic differentiation capacity, owing to abundant immune cells. Conversely, KD results in greater bone resorption than bone formation due to depletion of MSCs and a relatively suppressed immune system, and this immune imbalance eventually leads to vertebral avascular necrosis. The site of action between immune cells and osteoclasts is expected to be a new therapeutic target, and these results may accelerate mechanistic and functional studies of osteoimmune cell types and specific gene action in vertebral avascular necrosis and pathological bone loss diseases, paving the way for drug discovery.

Adipose stem cells in tissue regeneration and repair: From bench to bedside

ADSCs are a large number of mesenchymal stem cells in Adipose tissue, which can be applied to tissue engineering. ADSCs have the potential of multi-directional differentiation, and can differentiate into bone tissue, cardiac tissue, urothelial cells, skin tissue, etc. Compared with other mesenchymal stem cells, ADSCs have a multitude of promising advantages, such as abundant number, accessibility in cell culture, stable function, and less immune rejection. There are two main methods to use ADSCs for tissue repair and regeneration. One is to implant the "ADSCs-scaffold composite" into the injured site to promote tissue regeneration. The other is cell-free therapy: using ADSC-exos or ADSC-CM alone to release a large number of miRNAs, cytokines and other bioactive substances to promote tissue regeneration. The tissue regeneration potential of ADSCs is regulated by a variety of cytokines, signaling molecules, and external environment. The differentiation of ADSCs into different tissues is also induced by growth factors, ions, hormones, scaffold materials, physical stimulation, and other factors. The specific mechanisms are complex, and most of the signaling pathways need to be further explored. This article reviews and summarizes the mechanism and clinical application of ADSCs in tissue injury repair so far, and puts forward further problems that need to be solved in this field, hoping to provide directions for further research in this field.

Basic fibroblast growth factor promotes meniscus regeneration through the cultivation of synovial mesenchymal stem cells via the CXCL6-CXCR2 pathway

OBJECTIVE

To investigate the efficacy of basic fibroblast growth factor (bFGF) in promoting meniscus regeneration by cultivating synovial mesenchymal stem cells (SMSCs) and to validate the underlying mechanisms.

METHODS

Human SMSCs were collected from patients with osteoarthritis. Eight-week-old nude rats underwent hemi-meniscectomy, and SMSCs in pellet form, either with or without bFGF (1.0 × 106 cells per pellet), were implanted at the site of meniscus defects. Rats were divided into the control (no transplantation), FGF (-) (pellet without bFGF), and FGF (+) (pellet with bFGF) groups. Different examinations, including assessment of the regenerated meniscus area, histological scoring of the regenerated meniscus and cartilage, meniscus indentation test, and immunohistochemistry analysis, were performed at 4 and 8 weeks after surgery.

RESULTS

Transplanted SMSCs adhered to the regenerative meniscus. Compared with the control group, the FGF (+) group had larger regenerated meniscus areas, superior histological scores of the meniscus and cartilage, and better meniscus mechanical properties. RNA sequencing of SMSCs revealed that the gene expression of chemokines that bind to CXCR2 was upregulated by bFGF. Furthermore, conditioned medium derived from SMSCs cultivated with bFGF exhibited enhanced cell migration, proliferation, and chondrogenic differentiation, which were specifically inhibited by CXCR2 or CXCL6 inhibitors.

CONCLUSION

SMSCs cultured with bFGF promoted the expression of CXCL6. This mechanism may enhance cell migration, proliferation, and chondrogenic differentiation, thereby resulting in superior meniscus regeneration and cartilage preservation.

Recent development in multizonal scaffolds for osteochondral regeneration

Osteochondral (OC) repair is an extremely challenging topic due to the complex biphasic structure and poor intrinsic regenerative capability of natural osteochondral tissue. In contrast to the current surgical approaches which yield only short-term relief of symptoms, tissue engineering strategy has been shown more promising outcomes in treating OC defects since its emergence in the 1990s. In particular, the use of multizonal scaffolds (MZSs) that mimic the gradient transitions, from cartilage surface to the subchondral bone with either continuous or discontinuous compositions, structures, and properties of natural OC tissue, has been gaining momentum in recent years. Scrutinizing the latest developments in the field, this review offers a comprehensive summary of recent advances, current hurdles, and future perspectives of OC repair, particularly the use of MZSs including bilayered, trilayered, multilayered, and gradient scaffolds, by bringing together onerous demands of architecture designs, material selections, manufacturing techniques as well as the choices of growth factors and cells, each of which possesses its unique challenges and opportunities.

Small molecule inhibitors of osteoarthritis: Current development and future perspective

Osteoarthritis (OA) is one of the common degenerative joint diseases in clinic. It mainly damages articular cartilage, causing pain, swelling and stiffness around joints, and is the main cause of disability of the elderly. Due to the unclear pathogenesis of osteoarthritis and the poor self-healing ability of articular cartilage, the treatment options for this disease are limited. At present, NSAIDs, Glucocorticoid and Duloxetine are the most commonly used treatment choice for osteoarthritis. Although it is somewhat effective, the adverse reactions are frequent and serious. The development of safer and more effective anti-osteoarthritis drugs is essential and urgent. This review summarizes recent advances in the pharmacological treatment of OA, focusing on small molecule inhibitors targeting cartilage remodeling in osteoarthritis as well as the research idea of reducing adverse effects by optimizing the dosage form of traditional drugs for the treatment of osteoarthritis. It should provide a reference for exploration of new potential treatment options.

Biological and Mechanical Factors and Epigenetic Regulation Involved in Tendon Healing

Tendons are an important part of the musculoskeletal system. Connecting muscles to bones, tendons convert force into movement. Tendon injury can be acute or chronic. Noticeably, tendon healing requires a long time span and includes inflammation, proliferation, and remodeling processes. The mismatch between endogenous and exogenous healing may lead to adhesion causing further negative effects. Management of tendon injuries and complications such as subsequent adhesion formation are still challenges for clinicians. Due to numerous factors, tendon healing is a complex process. This review introduces the role of various biological and mechanical factors and epigenetic regulation processes involved in tendon healing.

Targeting FGFRs for tumor therapy: current status and novel strategies

The FGF receptors (FGFRs) belong to a family of receptor tyrosine kinases. Abundant evidence shows that FGFRs are closely related to tumor cell invasion and angiogenesis. Hence, targeted modulation of FGFRs has become an effective strategy for cancer treatment. Recently, the development of small-molecule inhibitors targeting FGFRs has been extensively studied, and three inhibitors have been approved for marketing. Based on the clinical problems with the current inhibitors, there is a need to develop novel inhibitors and technologies to address the pitfalls. This review summarizes recent advances in small-molecule inhibitors targeting FGFRs, focusing on structure-activity relationships. Moreover, recent progress of novel technologies are summarized to provide a reference for promoting the application of drugs targeting FGFRs in tumor therapy.

Cyclic and dimeric fibroblast growth factor 2 variants with high biomedical potential

Fibroblast growth factor 2 (FGF2) is a pleiotropic protein engaged in the regulation of key cellular processes in a wide spectrum of cells. FGF2 is an important object of basic research as well as a molecule used in regenerative medicine, in vitro cell culture maintenance, and as an anticancer drug carrier. However, the unsatisfactory stability and pleiotropic activities of the wild-type FGF2 largely limit its use as a medical product. To overcome these limitations, we have designed a set of FGF2-based macromolecules via sortase A-mediated cyclization and oligomerization. We obtained heparin-switchable FGF2 variants with enhanced stability and improved ability to stimulate cell proliferation and migration. We have shown that stimulation of glucose uptake by adipocytes is modulated by the architecture of FGF2 oligomers. Moreover, we used hyper-stable FGF2 variants for the construction of highly effective drug carriers for selective killing of FGFR1-overproducing cancer cells. The strategy for FGF2 engineering presented in this work provides novel insights into the design of growth factor variants for regenerative and anti-cancer precise medicine.

Fabrication of Tissue-Engineered Cartilage Using Decellularized Scaffolds and Chondrocytes

In this paper, we aim to explore the application value of tissue engineering for the construction of artificial cartilage in vitro. Chondrocytes from healthy porcine articular cartilage tissue were seeded on articular cartilage extracellular matrix (ACECM) scaffolds and cultivated. Type II collagen immunofluorescent staining was used to assess secretion from the extracellular matrix. Chondrocytes, which were mainly polygonal and cobblestone-shaped, were inoculated on ACECM-oriented scaffolding for 7 days, and the neo-tissue showed translucent shape and toughness. Using inverted and fluorescence microscopy, we found that chondrocytes on the scaffolds performed well in terms of adhesion and growth, and they secreted collagen type II. Moreover, the porcine ACECM scaffolds had good biocompatibility. The inflammatory cell detection, cellular immune response assay and humoral immune response assay showed porcine ACECM scaffolds were used for xenotransplantation without significant immune inflammatory response. All these findings reveal that ACECM-oriented scaffold is an ideal natural biomaterial for cartilage tissue engineering.

New developments in the biology of fibroblast growth factors

The fibroblast growth factor (FGF) family is composed of 18 secreted signaling proteins consisting of canonical FGFs and endocrine FGFs that activate four receptor tyrosine kinases (FGFRs 1-4) and four intracellular proteins (intracellular FGFs or iFGFs) that primarily function to regulate the activity of voltage-gated sodium channels and other molecules. The canonical FGFs, endocrine FGFs, and iFGFs have been reviewed extensively by us and others. In this review, we briefly summarize past reviews and then focus on new developments in the FGF field since our last review in 2015. Some of the highlights in the past 6 years include the use of optogenetic tools, viral vectors, and inducible transgenes to experimentally modulate FGF signaling, the clinical use of small molecule FGFR inhibitors, an expanded understanding of endocrine FGF signaling, functions for FGF signaling in stem cell pluripotency and differentiation, roles for FGF signaling in tissue homeostasis and regeneration, a continuing elaboration of mechanisms of FGF signaling in development, and an expanding appreciation of roles for FGF signaling in neuropsychiatric diseases. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology Congenital Diseases > Stem Cells and Development Cancer > Stem Cells and Development.

Advanced Nanofiber-Based Scaffolds for Achilles Tendon Regenerative Engineering

The Achilles tendon (AT) is responsible for running, jumping, and standing. The AT injuries are very common in the population. In the adult population (21–60 years), the incidence of AT injuries is approximately 2.35 per 1,000 people. It negatively impacts people’s quality of life and increases the medical burden. Due to its low cellularity and vascular deficiency, AT has a poor healing ability. Therefore, AT injury healing has attracted a lot of attention from researchers. Current AT injury treatment options cannot effectively restore the mechanical structure and function of AT, which promotes the development of AT regenerative tissue engineering. Various nanofiber-based scaffolds are currently being explored due to their structural similarity to natural tendon and their ability to promote tissue regeneration. This review discusses current methods of AT regeneration, recent advances in the fabrication and enhancement of nanofiber-based scaffolds, and the development and use of multiscale nanofiber-based scaffolds for AT regeneration.

Function of peripheral nerves in the development and healing of tendon and bone

Although the functions of the peripheral nervous system in whole body homeostasis and sensation have been understood for many years, recent investigation has uncovered new roles for innervation in the musculoskeletal system. This review centers on advances regarding the function of nerves in the development and repair of two connected tissues: tendon and bone. Innervation in healthy tendons is generally confined to the tendon sheaths, and tendon-bone attachment units are typically aneural. In contrast to tendon, bone is an innervated and vascularized structure. Historically, the function of abundant peripheral nerves in bone has been limited to pain and some non-painful sensory perception in disease and injury. Indeed, much of our understanding of peripheral nerves in tendons, bones, and entheses is limited to the source and type of innervation in healthy and injured tissues. However, more recent studies have made important observations regarding the appearance, type, and innervation patterns of nerves during embryonic and postnatal development and in response to injury, which suggest a more expansive role for peripheral nerves in the formation of musculoskeletal tissues. Indeed, tendons and bones develop in a close spatiotemporal relationship in the embryonic mesoderm. Models of limb denervation have shed light on the importance of sensory innervation in bone and to a lesser extent, tendon development, and more recent work has unraveled key nerve signaling pathways. Furthermore, loss of sensory innervation also impairs healing of bone fractures and may contribute to chronic tendinopathy. However, more study is required to translate our knowledge of peripheral nerves to therapeutic strategies to combat bone and tendon diseases.

Controlled growth factor delivery system with osteogenic-angiogenic coupling effect for bone regeneration

Objective

Bone regeneration involves a coordinated cascade of events that are regulated by several cytokines and growth factors, among which bone morphogenic protein-2 (BMP-2), vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2) play important roles. In this study, we investigated the effects of dual release of the three growth factors on bone regeneration in femur defects.

Methods

A composite consisting of Gelatin microparticles loaded with VEGF/FGF-2 and poly(lactic-co-glycolic acid)-poly(ethylene glycol)-carboxyl (PLGA-PEG-COOH) microparticles loaded with BMP-2 encapsulated in a nano hydroxyapatite-poly actic-co-glycolic acid (nHA-PLGA) scaffold was prepared for the dual release of the growth factors.

Results

On the 14th day, decreased release rate of BMP-2 compared with FGF-2 and VEGF was observed. However, after 14 days, compared to FGF-2 and VEGF, BMP-2 showed an increased release rate. Controlled dual release of BMP-2 and VEGF, FGF-2 resulted in a significant osteogenic differentiation of bone mesenchymal stem cells (BMSCs). Moreover, effects of the composite scaffold on functional connection of osteoblast-vascular cells during bone development were evaluated. The synergistic effects of dual delivery of growth factors were shown to promote the expression of VEGF in BMSCs. Increased secretion of VEGF from BMSCs promoted the proliferation and angiogenic differentiation of human umbilical vein endothelial cells (HUVECs) in the co-culture system. At 12 weeks after implantation, blood vessel and bone formation were analyzed by micro-CT and histology. The composite scaffold significantly promoted the formation of blood vessels and new bone in femur defects.

Conclusions

These findings demonstrate that dual delivery of angiogenic factors and osteogenic factors from Gelatin and PLGA-PEG-COOH microparticles-based composite scaffolds exerted an osteogenic-angiogenic coupling effect on bone regeneration. This approach will inform on the development of appropriate designs of high-performance bioscaffolds for bone tissue engineering.

Biomaterial-based delivery of nucleic acids for tissue regeneration

Gene therapy is a promising novel method of tissue regeneration by stimulating or inhibiting key signaling pathways. However, their therapeutic applications in vivo are largely limited by several physiological obstacles, such as degradation of nucleases, impermeability of cell membranes, and transport to the desired intracellular compartments. Biomaterial-based gene delivery systems can overcome the problems of stability and local drug delivery, and can temporarily control the overexpression of therapeutic genes, leading to the local production of physiologically relevant levels of regulatory factors. But the gene delivery of biomaterials for tissue regeneration relies on multi-factor design. This review aims to outline the impact of gene delivery methods, therapeutic genes and biomaterials selection on this strategy, emphatically introduce the latest developments in the design of gene delivery vehicles based on biomaterials, summarize the mechanism of nucleic acid for tissue regeneration, and explore the strategies of nucleic acid delivery vehicles for various tissue regeneration.

Nanocomposite scaffolds for accelerating chronic wound healing by enhancing angiogenesis

Skin is the body's first barrier against external pathogens that maintains the homeostasis of the body. Any serious damage to the skin could have an impact on human health and quality of life. Tissue engineering aims to improve the quality of damaged tissue regeneration. One of the most effective treatments for skin tissue regeneration is to improve angiogenesis during the healing period. Over the last decade, there has been an impressive growth of new potential applications for nanobiomaterials in tissue engineering. Various approaches have been developed to improve the rate and quality of the healing process using angiogenic nanomaterials. In this review, we focused on molecular mechanisms and key factors in angiogenesis, the role of nanobiomaterials in angiogenesis, and scaffold-based tissue engineering approaches for accelerated wound healing based on improved angiogenesis.