Apolipoprotein E impairs aged bone fracture healing

Abstract Bone fracture healing and osteoblast differentiation are impaired with advanced age. Using a combination of parabiosis and proteomic models, we identified apolipoprotein E (ApoE) to be an aging factor in bone regeneration. Circulating levels of ApoE increased with age in patients and in mice. ApoE impaired bone fracture healing by decreasing bone deposition in the fracture callus which subsequently decreased the mechanical strength of healed tissue. Osteoblasts serve as the sole bone forming cells within the body. In tissue culture models, ApoE treatment decreased osteoblast differentiation and activity which led to decreased matrix formation and mineralization. This inhibition of osteoblast differentiation relied on down-regulation of the Wnt/β-catenin pathway. In mouse models, aged bone repair was rejuvenated when we lowered circulating ApoE levels using a hepatotropic AAV-siRNA model – serving as a proof of concept that ApoE can be targeted to improve bone repair in an older population. While promising, knockdown of circulating ApoE in such a fashion is likely not translatable to patient care. Thus, current work in our laboratory is focused on developing treatment strategies that temporally decrease circulating ApoE levels and consequently improve bone healing after acute injury and/or surgical orthopedic procedure in the geriatric population.

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Chronic psychosocial stress compromises the immune response and endochondral ossification during bone fracture healing via β-AR signaling

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1819218116 ◽

2019 ◽

Vol 116 (17) ◽

pp. 8615-8622 ◽

Cited By ~ 11

Author(s):

Melanie Haffner-Luntzer ◽

Sandra Foertsch ◽

Verena Fischer ◽

Katja Prystaz ◽

Miriam Tschaffon ◽

...

Keyword(s):

Immune Response ◽

Inflammatory Response ◽

Fracture Healing ◽

Bone Fracture ◽

Psychosocial Stress ◽

Modern Society ◽

Bone Fracture Healing ◽

Fracture Callus ◽

Chronic Psychosocial Stress ◽

Late Stages

Chronic psychosocial stress/trauma represents an increasing burden in our modern society and a risk factor for the development of mental disorders, including posttraumatic stress disorder (PTSD). PTSD, in turn, is highly comorbid with a plethora of inflammatory disorders and has been associated with increased bone fracture risk. Since a balanced inflammatory response after fracture is crucial for successful bone healing, we hypothesize that stress/trauma alters the inflammatory response after fracture and, consequently, compromises fracture healing. Here we show, employing the chronic subordinate colony housing (CSC) paradigm as a clinically relevant mouse model for PTSD, that mice subjected to CSC displayed increased numbers of neutrophils in the early fracture hematoma, whereas T lymphocytes and markers for cartilage-to-bone transition and angiogenesis were reduced. At late stages of fracture healing, CSC mice were characterized by decreased bending stiffness and bony bridging of the fracture callus. Strikingly, a single systemic administration of the β-adrenoreceptor (AR) blocker propranolol before femur osteotomy prevented bone marrow mobilization of neutrophils and invasion of neutrophils into the fracture hematoma, both seen in the early phase after fracture, as well as a compromised fracture healing in CSC mice. We conclude that chronic psychosocial stress leads to an imbalanced immune response after fracture via β-AR signaling, accompanied by disturbed fracture healing. These findings offer possibilities for clinical translation in patients suffering from PTSD and fracture.

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Knockdown of SERPINB2 enhances the osteogenic differentiation of human bone marrow mesenchymal stem cells via activation of the Wnt/β-catenin signalling pathway

Stem Cell Research & Therapy ◽

10.1186/s13287-021-02581-6 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Kai Hang ◽

Li Ying ◽

Jinwu Bai ◽

Yibo Wang ◽

Zhihui Kuang ◽

...

Keyword(s):

Fracture Healing ◽

Osteogenic Differentiation ◽

Bone Fracture ◽

Osteoblast Differentiation ◽

Tibial Fracture ◽

Bone Fractures ◽

Bone Fracture Healing ◽

Non Union

Abstract Background Globally, bone fractures are the most common musculoskeletal trauma, and approximately 8–10% of cases that fall into the categories of delayed or non-union healing. To date, there are no efficient pharmacological agents to accelerate the healing of bone fractures. Thus, it is necessary to find new strategies that accelerate bone healing and reduce the incidence of non-union or delayed fracture healing. Previous studies have revealed that the plasminogen activation system has been demonstrated to play an important role in bone metabolism. However, the function of SERPINB2 in the osteogenesis of hBMSCs remains unclear. Therefore, in this study, we investigated the effects and mechanism of SERPINB2 on osteogenic differentiation. Methods We investigated the osteogenesis effects of hBMSCs by both exogenous SerpinB2 protein and SERPINB2 gene silencing in vitro. Cell proliferation assay was used to assess the effect of exogenous SerpinB2 or SERPINB2 silencing on proliferation of hBMSCs. qPCR and Western blotting analysis detected the expression of target genes and proteins respectively. ALP staining was used to evaluated ALP activity and Alizarin Red staining (ARS) was used to evaluate mineral deposition. In vivo, a murie tibial fracture model was established, histological evaluation and radiographic analysis was used to confirm the therapeutic effects of SERPINB2 silencing in fracture healing. Statistical significance between two groups was determined by Student’s t test, one-way ANOVA or Bonferroni’s post-hoc test according to the distribution of the tested population. Results The addition of exogenous SerpinB2 protein inhibted osteoblast differentiation of hBMSCs in vitro, while SERPINB2 gene silencing significant promote osteoblast differentiation of hBMSCs in vitro. And silenced SERPINB2 gene also increased mineral deposits. Moreover, β-catenin levels were up-regulated by SERPINB2 gene depletion. And the enhancement of osteogenic differentiation induced by SERPINB2 silencing was almost inhibited by specific Wnt/β-catenin signaling pathway inhibitor. In a murine tibial fracture model, local injection of SERPINB2 siRNA improved bone fracture healing. Conclusions Taken together, these findings indicate that SERPINB2 silencing promoted osteogenic differentiation of BMSCs via the Wnt/β-catenin signaling pathway, and silenced SERPINB2 in vivo effectively promotes fracture healing, suggesting that SERPINB2 may be a novel target for bone fracture healing.

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Lowering circulating apolipoprotein E levels improves aged bone fracture healing

JCI Insight ◽

10.1172/jci.insight.129144 ◽

2019 ◽

Vol 4 (18) ◽

Cited By ~ 4

Author(s):

Rong Huang ◽

Xiaohua Zong ◽

Puviindran Nadesan ◽

Janet L. Huebner ◽

Virginia B. Kraus ◽

...

Keyword(s):

Apolipoprotein E ◽

Fracture Healing ◽

Bone Fracture ◽

Bone Fracture Healing

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YAP and TAZ promote periosteal osteoblast precursor expansion and differentiation for fracture repair

10.1101/2020.03.17.995761 ◽

2020 ◽

Cited By ~ 1

Author(s):

Christopher D. Kegelman ◽

Madhura P. Nijsure ◽

Yasaman Moharrer ◽

Hope B. Pearson ◽

James H. Dawahare ◽

...

Keyword(s):

Bone Formation ◽

Fracture Healing ◽

Bone Fracture ◽

Callus Formation ◽

Fracture Repair ◽

Binding Motif ◽

Adult Onset ◽

Bone Fracture Healing ◽

Fracture Callus ◽

Endochondral Bone

ABSTRACTIn response to bone fracture, periosteal progenitor cells proliferate, expand, and differentiate to form cartilage and bone in the fracture callus. These cellular functions require the coordinated activation of multiple transcriptional programs, and the transcriptional regulators Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) regulate osteochondroprogenitor activation during endochondral bone development. However, recent observations raise important distinctions between the signaling mechanisms used to control bone morphogenesis and repair. Here, we tested the hypothesis that YAP and TAZ regulate osteochondroprogenitor activation during endochondral bone fracture healing. Constitutive YAP and/or TAZ deletion from Osterix-expressing cells impaired both cartilage callus formation and subsequent mineralization. However, this could be explained either by direct defects in osteochondroprogenitor differentiation after fracture, or by developmental deficiencies in the progenitor cell pool prior to fracture. Consistent with the second possibility, we found that developmental YAP/TAZ deletion produced long bones with impaired periosteal thickness and cellularity. Therefore, to remove the contributions of developmental history, we next generated adult onset-inducible knockout mice (using Osx1-CretetOff) in which YAP and TAZ were deleted prior to fracture, but after normal development. Adult onset-induced YAP/TAZ deletion had no effect on cartilaginous callus formation, but impaired bone formation at 14 days post-fracture (dpf). Earlier, at 4 dpf, adult onset-induced YAP/TAZ deletion impaired the proliferation and expansion of osteoblast precursor cells located in the shoulder of the callus. Further, activated periosteal cells isolated from this region at 4 dpf exhibited impaired osteogenic differentiation in vitro upon YAP/TAZ deletion. Finally, confirming the effects on osteoblast function in vivo, adult onset-induced YAP/TAZ deletion impaired bone formation in the callus shoulder at 7 dpf, prior to the initiation of endochondral ossification. Together, these data show that YAP and TAZ promote the expansion and differentiation of periosteal osteoblast precursors to accelerate bone fracture healing.

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Knockdown of SERPINB2 enhances the osteogenic differentiation of human bone marrow mesenchymal stem cells via activation of the Wnt/β-catenin signalling pathway

10.21203/rs.3.rs-624846/v1 ◽

2021 ◽

Author(s):

Kai Hang ◽

Li Ying ◽

Jinwu Bai ◽

Yibo Wang ◽

Zhihui Kuang ◽

...

Keyword(s):

Fracture Healing ◽

Osteogenic Differentiation ◽

Bone Fracture ◽

Osteoblast Differentiation ◽

Tibial Fracture ◽

Bone Fractures ◽

Bone Fracture Healing ◽

Non Union

Abstract Background Globally, bone fractures are the most common musculoskeletal trauma, and approximately 8–10% of cases that fall into the categories of delayed or non-union healing. Treatment of impaired healing in these patients not only represents a tremendous burden on healthcare systems but also increases patients’ pain and financial burdens. To date, there are no efficient pharmacological agents to accelerate the healing of bone fractures. Thus, it is necessary to find new strategies that accelerate bone healing and reduce the incidence of non-union or delayed fracture healing. Previous studies have revealed that the plasminogen activation system has been demonstrated to play an important role in bone metabolism. However, the function of SERPINB2 in the osteogenesis of hBMSCs remains unclear. Therefore, in this study, we investigated the effects and mechanism of Apelin on osteogenic differentiation. Methods We investigated the osteogenesis effects of hBMSCs by both exogenous SERPINB2 protein and SERPINB2 silencing in vitro. Cell proliferation assay was used to assess the effect of exogenous SERPINB2 or SERPINB2 silencing on proliferation of hBMSCs. qPCR and Western blotting analysis detected the expression of target genes and proteins respectively. ALP staining was used to evaluated ALP activity and Alizarin Red staining (ARS) was used to evaluate mineral deposition. In vivo, a murie tibial fracture model was established, histological evaluation and radiographic analysis was used to confirm the therapeutic effects of SERPINB2 silencing in fracture healing. statistical significance between two groups was determined by Student’s t test, one-way ANOVA or Bonferroni’s post-hoc test according to the distribution of the tested population.Results The addition of exogenous SERPINB2 protein inhibted osteoblast differentiation of hBMSCs in vitro, while SERPINB2 gene silencing significant promote osteoblast differentiation of hBMSCs in vitro. And silence SERPINB2 gene also increased mineral deposits. Moreover, β-catenin levels were up-regulated by SERPINB2 gene depletion. And the enhancement of osteogenic differentiation induced by SERPINB2 silencing was almost inhibited by specific Wnt/β-catenin signaling pathway inhibitors. In a murine tibial fracture model, local injection of SERPINB2 siRNA improved bone fracture healing. Conclusions Taken together, these findings indicate that SERPINB2 silencing promoted osteogenic differentiation of BMSCs via the Wnt/β-catenin signaling pathway, and silenced SERPINB2 in vivo effectively promotes fracture healing, suggesting that SERPINB2 may be a novel target for bone fracture healing.

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