RESUMEN
BACKGROUND: Bone regeneration is a well-regulated dynamic process, of which the prominent role of the immune system on bone homeostasis is more and more revealed by recent research. Before fully activation of the bone remodeling cells, the immune system needs to clean up the microenvironment in facilitating the bone repair initiation. Furthermore, this microenvironment must be maintained properly by various mechanisms over the entire bone regeneration process. OBJECTIVE: This review aims to summarize the role of the T-helper 17/Regulatory T cell (Th17/Treg) balance in bone cell remodeling and discuss the relevant progress in bone tissue engineering. RESULTS: The role of the immune response in the early stages of bone regeneration is crucial, especially the impact of the Th17/Treg balance on osteoclasts, mesenchymal stem cells (MSCs), and osteoblasts activity. By virtue of these knowledge advancements, innovative approaches in bone tissue engineering, such as nano-structures, hydrogel, and exosomes, are designed to influence the Th17/Treg balance and thereby augment bone repair and regeneration. CONCLUSION: Targeting the Th17/Treg balance is a promising innovative strategy for developing new treatments to enhance bone regeneration, thus offering potential breakthroughs in bone injury clinics.
Asunto(s)
Regeneración Ósea , Huesos , Linfocitos T Reguladores , Células Th17 , Ingeniería de Tejidos , Humanos , Linfocitos T Reguladores/inmunología , Ingeniería de Tejidos/métodos , Regeneración Ósea/inmunología , Animales , Células Th17/inmunología , Huesos/inmunología , Células Madre Mesenquimatosas/inmunología , Células Madre Mesenquimatosas/metabolismo , Remodelación Ósea/inmunología , Osteoblastos/inmunología , Osteoclastos/inmunología , Osteoclastos/metabolismoRESUMEN
Bone remodeling and bone regeneration are essential for preserving skeletal integrity and maintaining mineral homeostasis. T cells, as key members of adaptive immunity, play a pivotal role in bone remodeling and bone regeneration by producing a range of cytokines and growth factors. In the physiological state, T cells are involved in the maintenance of bone homeostasis through interactions with mesenchymal stem cells, osteoblasts, and osteoclasts. In pathological states, T cells participate in the pathological process of different types of osteoporosis through interaction with estrogen, glucocorticoids, and parathyroid hormone. During fracture healing for post-injury repair, T cells play different roles during the inflammatory hematoma phase, the bone callus formation phase and the bone remodeling phase. Targeting T cells thus emerges as a potential strategy for regulating bone homeostasis. This article reviews the research progress on related mechanisms of T cells immunity involved in bone remodeling and bone regeneration, with a view to providing a scientific basis for targeting T cells to regulate bone remodeling and bone regeneration.
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Regeneración Ósea , Remodelación Ósea , Linfocitos T , Remodelación Ósea/inmunología , Remodelación Ósea/fisiología , Humanos , Regeneración Ósea/inmunología , Linfocitos T/inmunología , AnimalesRESUMEN
Guided bone regeneration (GBR) is one of the most widely used and thoroughly documented alveolar bone augmentation surgeries. However, implanting GBR membranes inevitably triggers an immune response, which can lead to inflammation and failure of bone augmentation. It has been shown that GBR membranes may significantly improve in vivo outcomes as potent immunomodulators, rather than solely serving as traditional barriers. Macrophages play crucial roles in immune responses and participate in the entire process of bone injury repair. The significant diversity and high plasticity of macrophages complicate our understanding of the immunomodulatory mechanisms underlying GBR. This review provides a comprehensive summary of recent findings on the potential role of macrophages in GBR for bone defects in situ. Specifically, macrophages can promote osteogenesis or fibrous tissue formation in bone defects and degradation or fibrous encapsulation of membranes. Moreover, GBR membranes can influence the recruitment and polarization of macrophages. Therefore, immunomodulating GBR membranes are primarily developed by improving macrophage recruitment and aggregation as well as regulating macrophage polarization. However, certain challenges remain to be addressed in the future. For example, developing more rational and sophisticated sequential delivery systems for macrophage activation reagents; addressing the interference of bone graft materials and dental implants; and understanding the correlations among membrane degradation, macrophage responses, and bone regeneration.
Asunto(s)
Regeneración Ósea , Macrófagos , Humanos , Regeneración Ósea/inmunología , Macrófagos/inmunología , Animales , Regeneración Tisular Dirigida/métodos , OsteogénesisRESUMEN
Trauma rapidly mobilizes the immune response of surrounding tissues and activates regeneration program. Manipulating immune response to promote tissue regeneration shows a broad application prospect. However, the understanding of bone healing dynamics at cellular level remains limited. Here, we characterize the landscape of immune cells after alveolar bone injury and reveal a pivotal role of infiltrating natural killer T (NKT) cells. We observe a rapid increase in NKT cells after injury, which inhibit osteogenic differentiation of mesenchymal stem cells (MSCs) and impair alveolar bone healing. Cxcl2 is up-regulated in NKT cells after injury. Systemic administration of CXCL2-neutralizing antibody or genetic deletion of Cxcl2 improves the bone healing process. In addition, we fabricate a gelatin-based porous hydrogel to deliver NK1.1 depletion antibody, which successfully promotes alveolar bone healing. In summary, our study highlights the importance of NKT cells in the early stage of bone healing and provides a potential therapeutic strategy for accelerating bone regeneration.
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Regeneración Ósea , Quimiocina CXCL2 , Células T Asesinas Naturales , Osteogénesis , Animales , Ratones , Regeneración Ósea/genética , Regeneración Ósea/inmunología , Diferenciación Celular , Quimiocina CXCL2/metabolismo , Quimiocina CXCL2/genética , Células Madre Mesenquimatosas/metabolismo , Células Madre Mesenquimatosas/citología , Ratones Endogámicos C57BL , Células T Asesinas Naturales/inmunología , Células T Asesinas Naturales/metabolismo , Osteogénesis/genética , Osteogénesis/inmunologíaRESUMEN
Various studies have been investigated the phenotypic and functional distinctions of craniofacial and long bone cells involved in bone regeneration. However, the process of bone tissue regeneration after bone grafting involves complicated interactions between different cell types at the donor-recipient site. Additionally, differences in alterations of the immune microenvironment at the recipient site remained to be explored. Osteoblasts (OBs) and macrophages (MØ) play essential roles in the bone restoration and regeneration processes in the bone and immune systems, respectively. The modulation of MØ on OBs has been extensively explored in the literature, whereas limited research has been conducted on the influence of OBs on the MØ phenotype and function. In the present study, OBs from the mandible and femur (MOBs and FOBs, respectively) promoted cranial defect regeneration in rats, with better outcomes noted in the MOBs-treated group. After MOBs transplantation, a significant inflammatory response was induced, accompanied by an early increase in IL-10 secretion. And then, there was an upregulation in M2-MØ-related cell markers and inflammatory factor expression. Condition media (CM) of OBs mildly inhibited apoptosis in MØ, enhanced their migration and phagocytic functions, and concurrently increased iNOS and Arg1 expression, with MOB-CM demonstrating more pronounced effects compared to FOB-CM. In conclusion, our investigation showed that MOBs and FOBs have the ability to modulate MØ phenotype and function, with MOBs exhibiting a stronger regulatory potential. These findings provide a new direction for improving therapeutic strategies for bone regeneration in autologous bone grafts from the perspective of the immune microenvironment.
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Regeneración Ósea , Fémur , Inmunomodulación , Macrófagos , Mandíbula , Osteoblastos , Macrófagos/inmunología , Mandíbula/citología , Mandíbula/inmunología , Fémur/citología , Fémur/inmunología , Osteoblastos/inmunología , Regeneración Ósea/inmunología , Masculino , Animales , Ratas , Ratas Sprague-Dawley , Separación CelularRESUMEN
Activating autologous stem cells after the implantation of biomaterials is an important process to initiate bone regeneration. Although several studies have demonstrated the mechanism of biomaterial-mediated bone regeneration, a comprehensive single-cell level transcriptomic map revealing the influence of biomaterials on regulating the temporal and spatial expression patterns of mesenchymal stem cells (MSCs) is still lacking. Herein, the osteoimmune microenvironment is depicted around the classical collagen/nanohydroxyapatite-based bone repair materials via combining analysis of single-cell RNA sequencing and spatial transcriptomics. A group of functional MSCs with high expression of matrix Gla protein (Mgp) is identified, which may serve as a pioneer subpopulation involved in bone repair. Remarkably, these Mgp high-expressing MSCs (MgphiMSCs) exhibit efficient osteogenic differentiation potential and orchestrate the osteoimmune microenvironment around implanted biomaterials, rewiring the polarization and osteoclastic differentiation of macrophages through the Mdk/Lrp1 ligand-receptor pair. The inhibition of Mdk/Lrp1 activates the pro-inflammatory programs of macrophages and osteoclastogenesis. Meanwhile, multiple immune-cell subsets also exhibit close crosstalk between MgphiMSCs via the secreted phosphoprotein 1 (SPP1) signaling pathway. These cellular profiles and interactions characterized in this study can broaden the understanding of the functional MSC subpopulations at the early stage of biomaterial-mediated bone regeneration and provide the basis for materials-designed strategies that target osteoimmune modulation.
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Regeneración Ósea , Proteínas de Unión al Calcio , Colágeno , Durapatita , Proteína Gla de la Matriz , Células Madre Mesenquimatosas , Células Madre Mesenquimatosas/metabolismo , Células Madre Mesenquimatosas/inmunología , Regeneración Ósea/genética , Regeneración Ósea/inmunología , Animales , Durapatita/metabolismo , Proteínas de Unión al Calcio/genética , Proteínas de Unión al Calcio/metabolismo , Ratones , Colágeno/metabolismo , Colágeno/genética , Proteínas de la Matriz Extracelular/genética , Proteínas de la Matriz Extracelular/metabolismo , Osteogénesis/efectos de los fármacos , Osteogénesis/genética , Osteogénesis/inmunología , Diferenciación Celular/genética , Materiales BiocompatiblesRESUMEN
Proper regulation of the innate immune response to bone biomaterials after implantation is pivotal for successful bone healing. Pro-inflammatory M1 and anti-inflammatory M2 macrophages are known to have an important role in regulating the healing response to biomaterials. Materials with defined structural and topographical features have recently been found to favourably modulate the innate immune response, leading to improved healing outcomes. Calcium phosphate bone grafts with submicron-sized needle-shaped surface features have been shown to trigger a pro-healing response through upregulation of M2 polarised macrophages, leading to accelerated and enhanced bone regeneration. The present review describes the recent research on these and other materials, all the way from benchtop to the clinic, including in vitro and in vivo fundamental studies, evaluation in clinically relevant spinal fusion models and clinical validation in a case series of 77 patients with posterolateral and/or interbody fusion in the lumbar and cervical spine. This research demonstrates the feasibility of enhancing biomaterial-directed bone formation by modulating the innate immune response through topographic surface features.
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Huesos/efectos de los fármacos , Huesos/inmunología , Curación de Fractura/efectos de los fármacos , Curación de Fractura/inmunología , Inmunidad Innata/efectos de los fármacos , Adulto , Anciano , Anciano de 80 o más Años , Materiales Biocompatibles/farmacología , Regeneración Ósea/efectos de los fármacos , Regeneración Ósea/inmunología , Fosfatos de Calcio/farmacología , Femenino , Humanos , Inmunidad Innata/inmunología , Activación de Macrófagos/efectos de los fármacos , Activación de Macrófagos/inmunología , Masculino , Persona de Mediana Edad , Osteogénesis/efectos de los fármacos , Osteogénesis/inmunologíaRESUMEN
This study aimed to discuss the expression of angiogenesis-related proteins in bone marrow mesenchymal stem cells (BMSCs) induced by osteoprotegerin (OGP) during osteogenic differentiation in rats, and to analyze the effect of fracture healing inflammatory factor TNF-É on the osteogenic differentiation of BMSCs of rats. BMSCs isolated and cultured from the third generation rats were taken as the research object. According to the addition amount of OGP, BMSCs were divided into control group, OGP (10-7 mol/L) group, OGP (10-8 mol/L) group, and OGP (10-9 mol/L) group. The cell growth and morphological characteristics of each group were observed by inverted phase contrast microscope, the cell proliferation rate was measured by MTT method, angiogenesis-related markers (platelet growth factor (VEGF), cingulate protein 5 (Fbln5), and angiogenin-like protein 4 (Angptl4)) were quantitatively detected by Western blot, and the effect of TNF-É on osteogenic differentiation was detected by CCK. Compared with the control group, MTT results showed that the value-added rate of cells in the OGP (10-8 mol/L) group reached the maximum at 9 days (P < 0.05). The ALP activity in osteoblasts in the OGP (10-8 mol/L) group reached the maximum at 9 days (P < 0.01). The OGP (10-8 mol/L) group had the highest expression of vascular regeneration proteins (VEGF, Fbln5, and Angptl4) (P < 0.05). CCK analysis showed that the TNF-É (1.0 ng/mL) group showed a significant increase in absorbance compared with the control group on 6 days (P < 0.05), and the OD value of the TNF-É (10 ng/mL) group decreased at all time points (P < 0.05). Overall, 10-8 mol/L OGP can induce the proliferation and osteogenic differentiation of MSCs, and promote the expression of angiogenesis-related proteins (VEGF, Fbln5, and Angptl4) during osteogenic differentiation. Besides, 1.0 ng/mL of TNF-É can also promote osteogenesis differentiation of BMSCs in the short term.
Asunto(s)
Regeneración Ósea/efectos de los fármacos , Células Madre Mesenquimatosas/metabolismo , Osteogénesis/efectos de los fármacos , Osteoprotegerina/farmacología , Animales , Regeneración Ósea/genética , Regeneración Ósea/inmunología , Diferenciación Celular/inmunología , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Curación de Fractura/efectos de los fármacos , Curación de Fractura/inmunología , Regulación de la Expresión Génica/inmunología , Humanos , Células Madre Mesenquimatosas/inmunología , Modelos Animales , Neovascularización Fisiológica/genética , Osteogénesis/inmunología , Osteoporosis/tratamiento farmacológico , Osteoprotegerina/uso terapéutico , Cultivo Primario de Células , RatasRESUMEN
Single trauma injuries or isolated fractures are often manageable and generally heal without complications. In contrast, high-energy trauma results in multi/poly-trauma injury patterns presenting imbalanced pro- and anti- inflammatory responses often leading to immune dysfunction. These injuries often exhibit delayed healing, leading to fibrosis of injury sites and delayed healing of fractures depending on the intensity of the compounding traumas. Immune dysfunction is accompanied by a temporal shift in the innate and adaptive immune cells distribution, triggered by the overwhelming release of an arsenal of inflammatory mediators such as complements, cytokines and damage associated molecular patterns (DAMPs) from necrotic cells. Recent studies have implicated this dysregulated inflammation in the poor prognosis of polytraumatic injuries, however, interventions focusing on immunomodulating inflammatory cellular composition and activation, if administered incorrectly, can result in immune suppression and unintended outcomes. Immunomodulation therapy is promising but should be conducted with consideration for the spatial and temporal distribution of the immune cells during impaired healing. This review describes the current state of knowledge in the spatiotemporal distribution patterns of immune cells at various stages during musculoskeletal wound healing, with a focus on recent advances in the field of Osteoimmunology, a study of the interface between the immune and skeletal systems, in long bone fractures. The goals of this review are to (1) discuss wound and fracture healing processes of normal and delayed healing in skeletal muscles and long bones; (2) provide a balanced perspective on temporal distributions of immune cells and skeletal cells during healing; and (3) highlight recent therapeutic interventions used to improve fracture healing. This review is intended to promote an understanding of the importance of inflammation during normal and delayed wound and fracture healing. Knowledge gained will be instrumental in developing novel immunomodulatory approaches for impaired healing.
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Sistema Musculoesquelético/lesiones , Cicatrización de Heridas/inmunología , Animales , Regeneración Ósea/inmunología , Callo Óseo/inmunología , Curación de Fractura/inmunología , Hematoma/inmunología , Humanos , Inmunomodulación , Inflamación/inmunología , Traumatismo Múltiple/inmunología , Músculo Esquelético/inmunología , Músculo Esquelético/lesiones , Sistema Musculoesquelético/inmunología , Regeneración/inmunología , Factores de TiempoRESUMEN
Generally, the addition of exogenous stem cells and host-to-scaffold immune responses restricts the clinical applications of hydroxyapatite (HA)/chitosan (CS) scaffolds for bone regeneration. To achieve "facilitated endogenous tissue engineering", magnetic M-type hexagonal ferrite (SrFe12O19) nanoparticles were incorporated into bone scaffolds to recruit endogenous stem cells. Then, lanthanum incorporation was utilized to regulate host-to-scaffold immune responses and to provide a pro-regenerative environment for recruited endogenous stem cells. Here, we first fabricated and characterized magnetic lanthanum-doped HA/CS scaffolds. The MLaHA/CS scaffolds were demonstrated to be effective at recruiting rat bone marrow mesenchymal stem cells (rBMSCs) and modulating host-to-scaffold immune responses by promoting macrophage polarization into the anti-inflammatory phenotype (M2) in vitro. By further examining the underlying mechanism, we found that MLaHA/CS scaffolds could promote the osteogenic differentiation of rBMSCs by upregulating the phosphorylation of the Smad 1/5/9 pathway. When MLaHA/CS scaffolds were implanted into rat calvarial defects, the incorporation of magnetic nanoparticles and lanthanum significantly promoted the new bone regeneration, as revealed by micro-CT assays and histological staining. Our findings suggest that MLaHA/CS shows great potential for use as a cell-free and biocompatible scaffold for bone regeneration.
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Materiales Biocompatibles/farmacología , Regeneración Ósea/efectos de los fármacos , Quitosano/farmacología , Durapatita/farmacología , Inmunomodulación/efectos de los fármacos , Lantano/farmacología , Andamios del Tejido/química , Animales , Materiales Biocompatibles/química , Regeneración Ósea/inmunología , Quitosano/química , Durapatita/química , Lantano/química , Fenómenos Magnéticos , Células Madre Mesenquimatosas/efectos de los fármacos , Células Madre Mesenquimatosas/inmunología , Ratones , Tamaño de la Partícula , Células RAW 264.7 , Propiedades de SuperficieRESUMEN
Interleukin-12 (IL-12) and IL-23 are thought to have central roles in inflammation and are critical to pathologies associated with inflammation-induced bone disorders. The deletion of IL-12p40 (a common subunit of IL-12 and IL-23) can improve bone regeneration. However, the relative roles of IL-12 and IL-23 in bone disorders are largely unknown. Methods: Ectopic bone formation and skull defect models were established to evaluate the relative roles of IL-12 and IL-23 in inflammatory bone disorders. Differences in bone mass among WT, IL-12p35-/-, and IL-12p40-/- mice (young and elderly) were detected by micro-CT. Osteogenic and osteoclastic activities were explored using ELISA, qRT-PCR, and histological analysis. Moreover, the mechanisms by which IL-12 and IL-23 regulated the differentiation of BMMSCs and RAW264.7 cells were explored using Alizarin Red and tartrate-resistant acid phosphatase staining in vitro. Apilimod was used to inhibit IL-12 and IL-23 production in vivo. Results: Mice deficient in IL-12p40 promoted bone formation and protected against aging-related bone loss. By contrast, bone loss was aggravated in IL-12-/- mice, suggesting that IL-23 may play a dominant role in inflammation-related bone disorders. Mechanistically, IL-12 and IL-23 coupled osteogenesis and osteoclastic activities to regulate bone homeostasis and repair. IL-23 deficiency increased bone formation and inhibited bone resorption. Finally, apilimod treatment significantly improved bone regeneration and calvarial defect repair. Conclusion: These data collectively uncover a previously unrecognized role of IL-23 in skeletal tissue engineering. Thus, IL-23 can act as a biomarker to predict diseases and treatment efficacy, and apilimod can be used as an effective therapeutic drug to combat inflammatory bone disorders.
Asunto(s)
Enfermedades Óseas/inmunología , Regeneración Ósea/inmunología , Resorción Ósea/inmunología , Inflamación/inmunología , Subunidad p35 de la Interleucina-12/fisiología , Subunidad p40 de la Interleucina-12/fisiología , Osteogénesis/inmunología , Animales , Masculino , Células Madre Mesenquimatosas , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Desnudos , Células RAW 264.7RESUMEN
Surgical trauma of biomaterial implantation significantly influences the immune system and the biological effects of biomaterials. Minimally invasive surgery has become a trend of clinical development but violating the concept of osteoimmunomodulation will hinder the biological effects of materials. Our study focused on biphasic calcium phosphate (BCP), the ectopia osteoinductive materials, filling the research blank of the significance of adaptive immunity crosstalk with bone biomaterials, and improving the interaction mechanism between bone biomaterials and immune response. Methods: The BCP bioceramics were implanted by conventional and minimally invasive methods in the gastrocnemius wild-type or T cells depleted mice to test the effect of ectopia osteoinduction. Moreover, flow cytometry was used to detect immune responses, T cell sorting and Western Blot molecular biology experiments, and transwell assays migration of mesenchymal stem cells (MSCs). Results: We found that BCP, an implantable osteoinductive material, could not activate the adaptive immune response mediated by T cells after minimally invasive surgery. Further studies revealed that under the conventional non-minimally invasive BCP implantation, a positive correlation existed between T cell recruitment and the infiltration and osteogenic differentiation of MSCs. Interestingly, after BCP was implanted by minimally invasive surgery or implanted in T cell depleted mice, MSCs infiltration and osteogenic differentiation were significantly reduced, and BCP could not achieve the biological effects of ectopia ossification. Finally, we confirmed that a certain extent inflammatory stimulation activated the adaptive immune response mediated by T cells, up-regulated the nuclear factor-κB (NF-κB) signal in T cells, released a large amount of chemokine C-C motif chemokine ligand 5(CCL5) to recruit MSCs to the surrounding material, and finally achieved the ideal effect of osteoinduction. Conclusion: From experimental research and clinical surgery, this study discovered that the T cells are indispensable in the ectopia ossification mediated by osteoinductive materials, put forward and confirmed the surgery method as a key variable factor restricting the application effect of biological materials, enriched the key mechanism of adaptive immunity in osteoimmunomodulation, and laid a theoretical foundation for the development of osteoinductive materials and bone tissue regeneration.
Asunto(s)
Materiales Biocompatibles/farmacología , Sustitutos de Huesos/farmacología , Inflamación/inmunología , Osteogénesis/efectos de los fármacos , Animales , Materiales Biocompatibles/efectos adversos , Regeneración Ósea/efectos de los fármacos , Regeneración Ósea/inmunología , Diferenciación Celular , Quimiocina CCL5/efectos de los fármacos , Quimiocina CCL5/metabolismo , Femenino , Citometría de Flujo/métodos , Hidroxiapatitas/farmacología , Inmunidad/efectos de los fármacos , Inmunidad/inmunología , Células Madre Mesenquimatosas/efectos de los fármacos , Ratones , Ratones Endogámicos C57BL , Procedimientos Quirúrgicos Mínimamente Invasivos/métodos , Modelos Animales , FN-kappa B/efectos de los fármacos , Osteogénesis/inmunología , Linfocitos T/inmunologíaRESUMEN
Fracture repair is initiated by a multitude of immune cells and induction of an inflammatory cascade. Alterations in the early healing response due to an aged adaptive immune system leads to impaired bone repair, delayed healing or even formation of non-union. However, immuno-senescence is not limited to the adaptive immunity, but is also described for macrophages, main effector cells from the innate immune system. Beside regulation of pro- and anti-inflammatory signaling, macrophages contribute to angiogenesis and granulation tissue maturation. Thus, it seems likely that an altered macrophage function due to aging may affect bone repair at various stages and contribute to age related deficiencies in bone regeneration. To prove this hypothesis, we analyzed the expression of macrophage markers and angiogenic factors in the early bone hematoma derived from young and aged osteotomized Spraque Dawley rats. We detected an overall reduced expression of the monocyte/pan-macrophage markers CD14 and CD68 in aged rats. Furthermore, the analysis revealed an impaired expression of anti-inflammatory M2 macrophage markers in hematoma from aged animals that was connected to a diminished revascularization of the bone callus. To verify that the age related disturbed bone regeneration was due to a compromised macrophage function, CD14+ macrophage precursors were transplanted locally into the osteotomy gap of aged rats. Transplantation rescued bone regeneration partially after 6 weeks, demonstrated by a significantly induced deposition of new bone tissue, reduced fibrosis and significantly improved callus vascularization.
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Envejecimiento/inmunología , Regeneración Ósea/inmunología , Fracturas Óseas/inmunología , Macrófagos/inmunología , Cicatrización de Heridas/inmunología , Factores de Edad , Animales , Antígenos CD/genética , Antígenos CD/inmunología , Antígenos CD/metabolismo , Antígenos de Diferenciación Mielomonocítica/genética , Antígenos de Diferenciación Mielomonocítica/inmunología , Antígenos de Diferenciación Mielomonocítica/metabolismo , Biomarcadores/metabolismo , Regeneración Ósea/genética , Regeneración Ósea/fisiología , Huesos/irrigación sanguínea , Huesos/inmunología , Huesos/lesiones , Femenino , Expresión Génica/genética , Expresión Génica/inmunología , Receptores de Lipopolisacáridos/genética , Receptores de Lipopolisacáridos/inmunología , Receptores de Lipopolisacáridos/metabolismo , Macrófagos/clasificación , Macrófagos/metabolismo , Osteotomía , Ratas Sprague-Dawley , Cicatrización de Heridas/genéticaRESUMEN
Extracellular matrices (ECMs) have emerged as promising off-the-shelf products to induce bone regeneration, with the capacity not only to activate osteoprogenitors, but also to influence the immune response. ECMs generated starting from living cells such as mesenchymal stromal cells (MSCs) have the potential to combine advantages of native tissue-derived ECMs (e.g., physiological presentation of multiple regulatory factors) with those of synthetic ECMs (e.g., customization and reproducibility of composition). MSC-derived ECMs could be tailored by enrichment not only in osteogenic cytokines, but also in immunomodulatory factors, to skew the innate immune response toward regenerative processes. After reviewing the different immunoregulatory properties of ECM components, here we propose different approaches to engineer ECMs enriched in factors capable to regulate macrophage polarization, recruit host immune and mesenchymal cells, and stimulate the synthesis of other immunoinstructive cytokines. Finally, we offer a perspective on the possible evolution of the paradigm based on biological and chemico-physical design considerations, and the use of gene editing approaches.
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Regeneración Ósea/inmunología , Matriz Extracelular/inmunología , Inmunidad Innata/inmunología , Osteogénesis/inmunología , Animales , Citocinas/inmunología , Humanos , Células Madre Mesenquimatosas/inmunologíaRESUMEN
There is increasing evidence that T lymphocytes play a key role in controlling endogenous regeneration. Regeneration appears to be impaired in case of local accumulation of CD8+ effector T cells (TEFF), impairing endogenous regeneration by increasing a primary "useful" inflammation toward a damaging level. Thus, rescuing regeneration by regulating the heightened pro-inflammatory reaction employing regulatory CD4+ T (TReg) cells could represent an immunomodulatory option to enhance healing. Hypothesis was that CD4+ TReg might counteract undesired effects of CD8+ TEFF. Using adoptive TReg transfer, bone healing was consistently improved in mice possessing an inexperienced immune system with low amounts of CD8+ TEFF. In contrast, mice with an experienced immune system (high amounts of CD8+ TEFF) showed heterogeneous bone repair with regeneration being dependent upon the individual TEFF/TReg ratio. Thus, the healing outcome can only be improved by an adoptive TReg therapy, if an unfavorable TEFF/TReg ratio can be reshaped; if the individual CD8+ TEFF percentage, which is dependent on the individual immune experience can be changed toward a favorable ratio by the TReg transfer. Remarkably, also in patients with impaired fracture healing the TEFF/TReg ratio was higher compared to uneventful healers, validating our finding in the mouse osteotomy model. Our data demonstrate for the first time the key-role of a balanced TEFF/TReg response following injury needed to reach successful regeneration using bone as a model system. Considering this strategy, novel opportunities for immunotherapy in patients, which are at risk for impaired healing by targeting TEFF cells and supporting TReg cells to enhance healing are possible.
Asunto(s)
Desarrollo Óseo/inmunología , Regeneración Ósea/inmunología , Linfocitos T CD8-positivos/inmunología , Inmunomodulación/inmunología , Linfocitos T Reguladores/inmunología , Traslado Adoptivo/métodos , Animales , Biomarcadores/sangre , Huesos/inmunología , Femenino , Fracturas Óseas/terapia , Humanos , Inmunoterapia/métodos , Recuento de Linfocitos , Masculino , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , Linfocitos T Reguladores/trasplanteRESUMEN
Immune cells and their soluble factors regulate skeletal cells during normal bone regeneration and pathological bone formation. Bacterial infections can trigger immune responses that activate pro-osteogenic pathways, but these are usually overshadowed by osteolysis and concerns of systemic inflammation. The aim of this study was to determine whether the transient local inflammatory reaction to non-viable bacterial immune agonists could lead to favourable new bone formation. In a series of rabbit studies, as proof-of-concept, how tibial intramedullary injection of viable or killed bacterial species affected bone remodelling and new bone formation was determined. Application of killed bacteria led to considerable new bone formation after 4 weeks, without the prolonged systemic inflammation and exaggerated bone lysis seen with active infection. The osteo-immunomodulatory effects of various species of killed bacteria and the dose response relationship were subsequently screened in ectopically-implanted ceramic scaffolds. Histomorphometry after 8 weeks showed that a relatively low dose of killed bacteria enhanced ectopic bone induction. Moreover, lipoteichoic acid - the bacterial cell-wall derived toll-like-receptor (TLR)-2 activator - was identified as an osteo-stimulatory factor. Collectively, the data indicated that bacterial stimuli could be harnessed to stimulate osteogenesis, which occurs through a synergy with osteoinductive signals. This finding holds promise for the use of non-viable bacteria, bacterial antigens, or their simplified analogues as immuno-modulatory bone regenerating tools in bone biomaterials.
Asunto(s)
Bacterias/inmunología , Regeneración Ósea/inmunología , Inflamación/inmunología , Inflamación/microbiología , Tibia/inmunología , Tibia/microbiología , Animales , Materiales Biocompatibles/farmacología , Femenino , Osteoblastos/inmunología , Osteogénesis/inmunología , Conejos , Ingeniería de Tejidos/métodos , Andamios del TejidoRESUMEN
A wide variety of biomaterials have been developed as both stabilizing structures for the injured bone and inducers of bone neoformation. They differ in chemical composition, shape, porosity, and mechanical properties. The most extensively employed and studied subset of bioceramics are calcium phosphate materials (CaPs). These materials, when transplanted alongside mesenchymal stem cells (MSCs), lead to ectopic (intramuscular and subcutaneous) and orthotopic bone formation in preclinical studies, and effective fracture healing in clinical trials. Human MSC transplantation in pre-clinical and clinical trials reveals very low engraftment in spite of successful clinical outcomes and their therapeutic actions are thought to be primarily through paracrine mechanisms. The beneficial role of transplanted MSC could rely on their strong immunomodulatory effect since, even without long-term engraftment, they have the ability to alter both the innate and adaptive immune response which is critical to facilitate new bone formation. This study presents the current knowledge of the immune response to the implantation of CaP biomaterials alone or in combination with MSC. In particular the central role of monocyte-derived cells, both macrophages and osteoclasts, in MSC-CaP mediated bone formation is emphasized. Biomaterial properties, such as macroporosity and surface microstructure, dictate the host response, and the ultimate bone healing cascade. Understanding intercellular communications throughout the inflammation, its resolution and the bone regeneration phase, is crucial to improve the current therapeutic strategies or develop new approaches.
Asunto(s)
Materiales Biocompatibles/farmacología , Regeneración Ósea , Fosfatos de Calcio/farmacología , Inmunomodulación/efectos de los fármacos , Trasplante de Células Madre Mesenquimatosas , Células Madre Mesenquimatosas/inmunología , Osteogénesis , Animales , Regeneración Ósea/efectos de los fármacos , Regeneración Ósea/inmunología , Humanos , Osteogénesis/efectos de los fármacos , Osteogénesis/inmunologíaRESUMEN
As cytotoxic (CD8+ ) T cells seem to impair shaft fracture healing, we hypothesized that depletion of CD8+ cells would instead improve healing of cancellous bone. Additionally, we also tested if CD8-depletion would influence the healing of ruptured Achilles tendons. Rats received a single injection of either anti-CD8 antibodies or saline and put through surgery 24 h later. Three different surgical interventions were performed as follows: (1) a drill hole in the proximal tibia with microCT (BV/TV) to assess bone formation; (2) a screw in the proximal tibia with mechanical evaluation (pull-out force) to assess fracture healing; (3) Achilles tendon transection with mechanical evaluation (force-at-failure) to assess tendon healing. Furthermore, CD8-depletion was confirmed with flow cytometry on peripheral blood. Flow cytometric analysis confirmed depletion of CD8+ cells (p < 0.001). Contrary to our hypothesis, depletion of CD8+ cells reduced the implant pull-out force by 19% (p < 0.05) and stiffness by 34% (p < 0.01), although the bone formation in the drill holes was the same as in the controls. Tendon healing was unaffected by CD8-depletion. Our results suggest that CD8+ cells have an important part in cancellous bone healing. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.
Asunto(s)
Tendón Calcáneo/fisiología , Regeneración Ósea/inmunología , Linfocitos T CD8-positivos/fisiología , Hueso Esponjoso/fisiología , Animales , Hueso Esponjoso/diagnóstico por imagen , Masculino , Ratas Sprague-Dawley , Microtomografía por Rayos XRESUMEN
The terminal complement complex (TCC) is formed on activation of the complement system, a crucial arm of innate immunity. TCC formation on cell membranes results in a transmembrane pore leading to cell lysis. In addition, sublytic TCC concentrations can modulate various cellular functions. TCC-induced effects may play a role in the pathomechanisms of inflammatory disorders of the bone, including rheumatoid arthritis and osteoarthritis. In this study, we investigated the effect of the TCC on bone turnover and repair. Mice deficient for complement component 6 (C6), an essential component for TCC assembly, and mice with a knockout of CD59, which is a negative regulator of TCC formation, were used in this study. The bone phenotype was analyzed in vivo, and bone cell behavior was analyzed ex vivo. In addition, the mice were subjected to a femur osteotomy. Under homeostatic conditions, C6-deficient mice displayed a reduced bone mass, mainly because of increased osteoclast activity. After femur fracture, the inflammatory response was altered and bone formation was disturbed, which negatively affected the healing outcome. By contrast, CD59-knockout mice only displayed minor skeletal alterations and uneventful bone healing, although the early inflammatory reaction to femur fracture was marginally enhanced. These results demonstrate that TCC-mediated effects regulate bone turnover and promote an adequate response to fracture, contributing to an uneventful healing outcome.