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Darwish NHE, Hussein KA, Elmasry K, Ibrahim AS, Humble J, Moustafa M, Awadalla F, Al-Shabrawey M. Bone Morphogenetic Protein-4 Impairs Retinal Endothelial Cell Barrier, a Potential Role in Diabetic Retinopathy. Cells 2023; 12:1279. [PMID: 37174679 PMCID: PMC10177364 DOI: 10.3390/cells12091279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/17/2023] [Accepted: 04/21/2023] [Indexed: 05/15/2023] Open
Abstract
Bone Morphogenetic Protein 4 (BMP4) is a secreted growth factor of the Transforming Growth Factor beta (TGFβ) superfamily. The goal of this study was to test whether BMP4 contributes to the pathogenesis of diabetic retinopathy (DR). Immunofluorescence of BMP4 and the vascular marker isolectin-B4 was conducted on retinal sections of diabetic and non-diabetic human and experimental mice. We used Akita mice as a model for type-1 diabetes. Proteins were extracted from the retina of postmortem human eyes and 6-month diabetic Akita mice and age-matched control. BMP4 levels were measured by Western blot (WB). Human retinal endothelial cells (HRECs) were used as an in vitro model. HRECs were treated with BMP4 (50 ng/mL) for 48 h. The levels of phospho-smad 1/5/9 and phospho-p38 were measured by WB. BMP4-treated and control HRECs were also immunostained with anti-Zo-1. We also used electric cell-substrate impedance sensing (ECIS) to calculate the transcellular electrical resistance (TER) under BMP4 treatment in the presence and absence of noggin (200 ng/mL), LDN193189 (200 nM), LDN212854 (200 nM) or inhibitors of vascular endothelial growth factor receptor 2 (VEGFR2; SU5416, 10 μM), p38 (SB202190, 10 μM), ERK (U0126, 10 μM) and ER stress (Phenylbutyric acid or PBA, 30 μmol/L). The impact of BMP4 on matrix metalloproteinases (MMP2 and MMP9) was also evaluated using specific ELISA kits. Immunofluorescence of human and mouse eyes showed increased BMP4 immunoreactivity, mainly localized in the retinal vessels of diabetic humans and mice compared to the control. Western blots of retinal proteins showed a significant increase in BMP4 expression in diabetic humans and mice compared to the control groups (p < 0.05). HRECs treated with BMP4 showed a marked increase in phospho-smad 1/5/9 (p = 0.039) and phospho-p38 (p = 0.013). Immunofluorescence of Zo-1 showed that BMP4-treated cells exhibited significant barrier disruption. ECIS also showed a marked decrease in TER of HRECs by BMP4 treatment compared to vehicle-treated HRECs (p < 0.001). Noggin, LDN193189, LDN212854, and inhibitors of p38 and VEGFR2 significantly mitigated the effects of BMP4 on the TER of HRECs. Our finding provides important insights regarding the role of BMP4 as a potential player in retinal endothelial cell dysfunction in diabetic retinopathy and could be a novel target to preserve the blood-retinal barrier during diabetes.
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Affiliation(s)
- Noureldien H. E. Darwish
- Eye Research Center, Department of Foundational Medical Studies, Oakland University William Beaumont School of Medicine, Rochester, MI 48309, USA
- Eye Research Institute, Oakland University, Rochester, MI 48309, USA
- Clinical Pathology Department, Faculty of Medicine, Mansoura University, Mansoura 35111, Egypt
| | - Khaled A. Hussein
- Oral and Dental Research Insitute, Department of Oral Medicine and Surgery, National Research Center, Cairo 11553, Egypt
| | - Khaled Elmasry
- Department of Oral Biology and Diagnostic Science, Dental College of Georgia, Augusta University, Augusta, GA 30912, USA
- Department of Anatomy, Mansoura Faculty of Medicine, Mansoura University, Mansoura 35111, Egypt
| | - Ahmed S. Ibrahim
- Department of Ophthalmology, Visual and Anatomical Sciences, School of Medicine, Wayne State University, Detroit, MI 48201, USA
- Department of Biochemistry, Faculty of Pharmacy, Mansoura University, Mansoura 35111, Egypt
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Julia Humble
- Eye Research Center, Department of Foundational Medical Studies, Oakland University William Beaumont School of Medicine, Rochester, MI 48309, USA
- Eye Research Institute, Oakland University, Rochester, MI 48309, USA
| | - Mohamed Moustafa
- Eye Research Center, Department of Foundational Medical Studies, Oakland University William Beaumont School of Medicine, Rochester, MI 48309, USA
- Eye Research Institute, Oakland University, Rochester, MI 48309, USA
| | - Fatma Awadalla
- Eye Research Center, Department of Foundational Medical Studies, Oakland University William Beaumont School of Medicine, Rochester, MI 48309, USA
- Eye Research Institute, Oakland University, Rochester, MI 48309, USA
- Clinical Pathology Department, Faculty of Medicine, Mansoura University, Mansoura 35111, Egypt
| | - Mohamed Al-Shabrawey
- Eye Research Center, Department of Foundational Medical Studies, Oakland University William Beaumont School of Medicine, Rochester, MI 48309, USA
- Eye Research Institute, Oakland University, Rochester, MI 48309, USA
- Department of Anatomy, Mansoura Faculty of Medicine, Mansoura University, Mansoura 35111, Egypt
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Al-Shabrawey M, Hussein K, Wang F, Wan M, Elmasry K, Elsherbiny N, Saleh H, Yu PB, Tawfik A, Ibrahim AS. Bone Morphogenetic Protein-2 Induces Non-Canonical Inflammatory and Oxidative Pathways in Human Retinal Endothelial Cells. Front Immunol 2021; 11:568795. [PMID: 33584642 PMCID: PMC7878387 DOI: 10.3389/fimmu.2020.568795] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 12/08/2020] [Indexed: 11/13/2022] Open
Abstract
The mechanisms of diabetic retinopathy (DR), are not yet fully understood. We previously demonstrated an upregulation of retinal bone morphogenetic protein-2 (BMP2) in experimental diabetes and in retinas of diabetic human subjects. The purpose of current study was to investigate the role of non-canonical inflammatory pathway in BMP2-induced retinal endothelial cell (REC) barrier dysfunction. For this purpose, we used RT-PCR and western blotting to evaluate the levels of BMP2 signaling components (BMP2, BMP4, BMP receptors), VEGF, phosphorylated p38 MAPK and NFκB, and oxidative stress markers in cultured human retinal endothelial cells (HRECs) subjected to BMP2 (50ng/ml) for up to 24 h. Also, effect of high glucose (HG, 30mM D-glucose) on the expression of BMP2 and its downstream genes was examined in HRECs. H2-DCF is a fluorogenic dye that measures the levels of cellular reactive oxygen species (ROS) was used to measure the pro-oxidative effect of BMP2. Moreover, we evaluated the effect of inhibiting p38 and VEGF signaling on BMP2-induced HRECs barrier dysfunction by measuring the trans-endothelial cell electrical resistance (TER) using electric cell-substrate impedance sensing (ECIS). We also tested the effect of HG on the integrity of HRECs barrier in the presence or absence of inhibitors of BMP2 signaling. Our data reveals that BMP2 and high glucose upregulates BMP components of the BMP signaling pathway (SMAD effectors, BMP receptors, and TGFβ ligand itself) and induces phosphorylation of p38 MAPK and NFκB with nuclear translocation of NFκB. Inhibition of p38 or NFκB attenuated BMP2-induced VEGF expression and barrier dysfunction in HRECs. Also, inhibition of VEGFR2 attenuated BMP2-induced barrier dysfunction. Moreover, BMP2 induces generation of ROS and endothelial nitric oxide synthase (eNOS) expression and activity in HRECs. Finally, HG upregulated BMP2 and its downstream genes (SMAD, BMP4, ALKs, and TGF-β) in HRECs and BMP2 inhibitors attenuated HG-induced HRECs barrier dysfunction. Our results suggest that in addition to the regular canonical SMAD signaling BMP2 induces non-canonical inflammatory pathway in HRECs via activation of p38/NFκB pathway that causes the upregulation of VEGF and the disruption of HRECs. Inhibition of BMP2 signaling is a potential therapeutic intervention to preserve endothelial cell barrier function in DR.
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Affiliation(s)
- Mohamed Al-Shabrawey
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia, Augusta University, Augusta, GA, United States
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, United States
- Department of Ophthalmology and Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA, United States
- Department of Anatomy, Mansoura Faculty of Medicine, Mansoura University, Mansoura, Egypt
| | - Khaled Hussein
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia, Augusta University, Augusta, GA, United States
- Department of Medicine and Surgery, Oral and Dental Research Division, National Research Centre, Cairo, Egypt
| | - Fang Wang
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia, Augusta University, Augusta, GA, United States
- Department of Traditional Chinese Medicine, School of Medicine, Jianghan University, Wuhan, China
| | - Ming Wan
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia, Augusta University, Augusta, GA, United States
- Department of Traditional Chinese Medicine, School of Medicine, Jianghan University, Wuhan, China
| | - Khaled Elmasry
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia, Augusta University, Augusta, GA, United States
- Department of Anatomy, Mansoura Faculty of Medicine, Mansoura University, Mansoura, Egypt
| | - Nehal Elsherbiny
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia, Augusta University, Augusta, GA, United States
- Department of Biochemistry, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Heba Saleh
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia, Augusta University, Augusta, GA, United States
| | - Paul B. Yu
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, United States
| | - Amany Tawfik
- Department of Oral Biology and Diagnostic Sciences, Dental College of Georgia, Augusta University, Augusta, GA, United States
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, United States
- Department of Ophthalmology and Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Ahmed S. Ibrahim
- Department of Biochemistry, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
- Department of Ophthalmology, Visual, and Anatomical Sciences, Department of Pharmacology, Wayne State University, Detroit, MI, United States
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Visser NJ, Rezaie ES, Friedrich PF, Kotsougiani D, Shin AY, Bishop AT. Effects of Surgical Angiogenesis on Segmental Bone Reconstruction With Cryopreserved Massive-Structural Allografts in a Porcine Tibia Model. J Orthop Res 2019; 37:1698-1708. [PMID: 31042307 PMCID: PMC6824922 DOI: 10.1002/jor.24318] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 04/12/2019] [Indexed: 02/04/2023]
Abstract
Cryopreserved bone allografts (CBA) used to reconstruct segmental bone defects provide immediate structural stability, but are vulnerable to infection, non-union and late stress fracture as the majority of the allograft remains largely avascular. We sought to improve the bone vascularity and bone formation of CBAs by surgical angiogenesis with an implanted arteriovenous (AV) bundle, using a porcine tibial defect model. Cryopreserved tibial bone allografts were transplanted in swine leukocyte antigen (SLA) mismatched Yucatan minipigs to reconstruct a 3.5 cm segmental tibial defect. A cranial tibial AV-bundle was placed within its intramedullary canal to induce angiogenesis. The AV bundle was patent in eight pigs and ligated in a control group of eight pigs. At 20 weeks neo-angiogenesis was evaluated by micro-angiography. Bone formation was measured by quantitative histomorphometry and micro-computed tomography. Seven of eight AV-bundles in the revascularized group were patent. One had thrombosed due to allograft displacement. Total vascular volume was higher in the revascularized allografts compared to the ligated group (p = 0.015). Revascularized allografts had increased levels of bone formation on the allograft endosteal surface compared to the ligated control group (p = 0.05). Surgical angiogenesis of porcine tibial CBAs by intramedullary implantation of an AV-bundle creates an enhanced autogenous neoangiogenic circulation and accelerates active bone formation on allograft endosteal surfaces. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1698-1708, 2019.
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Affiliation(s)
- Noortje J Visser
- Microvascular Research Laboratory, Department of Orthopedic
Surgery, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA
| | - Elisa S Rezaie
- Microvascular Research Laboratory, Department of Orthopedic
Surgery, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA
| | - Patricia F Friedrich
- Microvascular Research Laboratory, Department of Orthopedic
Surgery, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA
| | - Dimitra Kotsougiani
- Microvascular Research Laboratory, Department of Orthopedic
Surgery, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA,Department of Hand-, Plastic- and Reconstructive Surgery,
-Burn Center-, BG Trauma Center Ludwigshafen, Department of Plastic Surgery,
University of Heidelberg, Heidelberg, Germany
| | - Alexander Y Shin
- Microvascular Research Laboratory, Department of Orthopedic
Surgery, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA
| | - Allen T Bishop
- Microvascular Research Laboratory, Department of Orthopedic
Surgery, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA
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Chen XJ, Liu S, Gao GZ, Yan DX, Jiang WS. Effects of vacuum sealing drainage on the treatment of cranial bone-exposed wounds in rabbits. ACTA ACUST UNITED AC 2017; 50:e5837. [PMID: 28977118 PMCID: PMC5625544 DOI: 10.1590/1414-431x20175837] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 08/16/2017] [Indexed: 11/21/2022]
Abstract
This study was designed to assess the efficacy of vacuum sealing drainage (VSD) on skull exposure wounds in rabbits and to investigate the underlying mechanism of the process. Full-thickness excisional circular wounds 2×2 cm with or without periosteum involvement were created in 88 New Zealand white rabbits (mean body weight: 3.0±0.65 kg). Animals were randomly divided into 4 groups: periosteum-intact wounds treated with traditional dressing (p+control), periosteum-intact wounds treated with VSD (p+VSD), periosteum-lacking wounds treated with traditional dressing (p–control) and periosteum-lacking wounds treated with VSD (p–VSD). The wounds treated with traditional dressing were covered with Vaseline gauze, while VSD treatment was accompanied with continuous –120 mmHg pressure. Finally, wound tissues were harvested for analysis of hydroxyproline content and histologic detection. VSD hastened the wound healing process significantly (P<0.05) compared to the corresponding control groups. VSD alleviated the inflammation reaction, accelerated re-epithelialization and facilitated the organization of collagen fibers into neat rows. During the wound healing process, the hydroxyproline content increased overtime [i.e., postoperative days (POD) 7, POD 10 and POD 15] in all four groups, and it peaked in the p+VSD group. VSD also promoted angiogenesis via increasing number and quality of collagen. We concluded that VSD can promote healing in bone-exposed wounds via increasing hydroxyproline content and vessel density, reducing inflammatory responses and generating ordered collagen arrangement.
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Affiliation(s)
- X J Chen
- Department of Burn and Plastic Surgery, the 253rd Hospital of People's Liberation Army, Xincheng District, Hohhot, Inner Mongolia, China
| | - S Liu
- Department of Burn and Plastic Surgery, the 253rd Hospital of People's Liberation Army, Xincheng District, Hohhot, Inner Mongolia, China
| | - G Z Gao
- Department of Burn and Plastic Surgery, the 253rd Hospital of People's Liberation Army, Xincheng District, Hohhot, Inner Mongolia, China
| | - D X Yan
- Department of Burn and Plastic Surgery, the 253rd Hospital of People's Liberation Army, Xincheng District, Hohhot, Inner Mongolia, China
| | - W S Jiang
- Department of Burn and Plastic Surgery, the 253rd Hospital of People's Liberation Army, Xincheng District, Hohhot, Inner Mongolia, China
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Patel R, Patel M, Kwak J, Iyer AK, Karpoormath R, Desai S, Rarh V. Polymeric microspheres: a delivery system for osteogenic differentiation. POLYM ADVAN TECHNOL 2017. [DOI: 10.1002/pat.4084] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Rajkumar Patel
- School of Electrical and Computer Engineering; The University of Seoul; Seoul 02504 Korea
| | - Madhumita Patel
- Department of Chemistry and Nano Science; Ewha Womans University; Seodaemun-gu Seoul 120-750 South Korea
| | - Jeonghun Kwak
- School of Electrical and Computer Engineering; The University of Seoul; Seoul 02504 Korea
| | - Arun K. Iyer
- Use-inspired Biomaterials & Integrated Nano Delivery (U-Bind) Systems Laboratory, Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health, Sciences; Wayne State University; 259 Mack Ave Detroit MI 48201 USA
| | - Rajshekhar Karpoormath
- Department of Pharmaceutical Chemistry, College of Health Sciences; University of Kwa Zulu Natal; Durban 4000 Africa
| | - Shrojal Desai
- Global Infusion Systems R&D at Hospira; Chicago, IL USA
| | - Vimal Rarh
- Department of Chemistry, S.G.T.B. Khalsa College; University of Delhi; Delhi 110007 India
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Herrmann M, Verrier S, Alini M. Strategies to Stimulate Mobilization and Homing of Endogenous Stem and Progenitor Cells for Bone Tissue Repair. Front Bioeng Biotechnol 2015; 3:79. [PMID: 26082926 PMCID: PMC4451737 DOI: 10.3389/fbioe.2015.00079] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 05/16/2015] [Indexed: 12/17/2022] Open
Abstract
The gold standard for the treatment of critical-size bone defects is autologous or allogenic bone graft. This has several limitations including donor site morbidity and the restricted supply of graft material. Cell-based tissue engineering strategies represent an alternative approach. Mesenchymal stem cells (MSCs) have been considered as a source of osteoprogenitor cells. More recently, focus has been placed on the use of endothelial progenitor cells (EPCs), since vascularization is a critical step in bone healing. Although many of these approaches have demonstrated effectiveness for bone regeneration, cell-based therapies require time consuming and cost-expensive in vitro cell expansion procedures. Accordingly, research is becoming increasingly focused on the homing and stimulation of native cells. The stromal cell-derived factor-1 (SDF-1) - CXCR4 axis has been shown to be critical for the recruitment of MSCs and EPCs. Vascular endothelial growth factor (VEGF) is a key factor in angiogenesis and has been targeted in many studies. Here, we present an overview of the different approaches for delivering homing factors to the defect site by absorption or incorporation to biomaterials, gene therapy, or via genetically manipulated cells. We further review strategies focusing on the stimulation of endogenous cells to support bone repair. Finally, we discuss the major challenges in the treatment of critical-size bone defects and fracture non-unions.
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Affiliation(s)
| | | | - Mauro Alini
- AO Research Institute Davos , Davos , Switzerland
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Healing of massive segmental femoral bone defects in minipigs by allogenic ASCs engineered with FLPo/Frt-based baculovirus vectors. Biomaterials 2015; 50:98-106. [DOI: 10.1016/j.biomaterials.2015.01.052] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 01/08/2015] [Accepted: 01/20/2015] [Indexed: 12/25/2022]
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Emulating native periosteum cell population and subsequent paracrine factor production to promote tissue engineered periosteum-mediated allograft healing. Biomaterials 2015; 52:426-40. [PMID: 25818449 DOI: 10.1016/j.biomaterials.2015.02.064] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 02/10/2015] [Accepted: 02/13/2015] [Indexed: 01/01/2023]
Abstract
Emulating autograft healing within the context of decellularized bone allografts has immediate clinical applications in the treatment of critical-sized bone defects. The periosteum, a thin, osteogenic tissue that surrounds bone, houses a heterogenous population of stem cells and osteoprogenitors. There is evidence that periosteum-cell derived paracrine factors, specifically vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP2), orchestrate autograft healing through host cell recruitment and subsequent tissue elaboration. In previous work, we demonstrated that the use of poly(ethylene glycol) (PEG) hydrogels as a tissue engineered (T.E.) periosteum to localize mesenchymal stem cells (MSCs) to the surface of decellularized bone enhances allograft healing and integration. Herein, we utilize a mixed population of 50:50 MSCs and osteoprogenitor cells to better mimic native periosteum cell population and paracrine factor production to further promote allograft healing. This mixed cell population was localized to the surface of decellularized allografts within degradable hydrogels and shown to expedite allograft healing. Specifically, bone callus formation and biomechanical graft-host integration are increased as compared to unmodified allografts. These results demonstrate the dual importance of periosteum-mediated paracrine factors orchestrating host cell recruitment as well as new bone formation while developing clinically translatable strategies for allograft healing and integration.
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Abstract
Angiogenesis is a vital component of bone healing. The formation of the new blood vessels at the fracture site restores the hypoxia and nutrient deprivation found at the early stages after fracture whilst at a later stage facilitates osteogenesis by the activity of the osteoprogenitor cells. Emerging evidence suggests that there are certain molecules and gene therapies that could promote new blood vessel formation and as a consequence enhance the local bone healing response. This article summarizes the current in vivo evidence on therapeutic approaches aiming at the augmentation of the angiogenic signalling during bone repair.
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Larsen M, Willems WF, Pelzer M, Friedrich PF, Dadsetan M, Bishop AT. Fibroblast growth factor-2 and vascular endothelial growth factor mediated augmentation of angiogenesis and bone formation in vascularized bone allotransplants. Microsurgery 2014; 34:301-7. [PMID: 24395434 DOI: 10.1002/micr.22221] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 12/09/2013] [Accepted: 12/20/2013] [Indexed: 01/13/2023]
Abstract
We previously demonstrated recipient-derived neoangiogenesis to maintain viability of living bone allogeneic transplants without long-term immunosuppression. The effect of cytokine delivery to enhance this process is studied. Vascularized femur transplantation was performed from Dark Agouti to Piebald Virol Glaxo rats. Poly(d,l-lactide-co-glycolide) microspheres loaded with buffer (N = 11), basic fibroblast growth factor (FGF2) (N = 10), vascular endothelial growth factor (VEGF) (N = 11), or both (N = 11) were inserted intramedullarly alongside a recipient-derived arteriovenous bundle. FK-506 was administered for 2 weeks. At 18 weeks, bone blood flow, microangiography, histologic, histomorphometric, and alkaline phosphatase measurements were performed. Bone blood flow was greater in the combined group than control and VEGF groups (P = 0.04). Capillary density was greater in the FGF2 group than in the VEGF and combined groups (P < 0.05). Bone viability, growth, and alkaline phosphatase activity did not vary significantly between groups. Neoangiogenesis in vascularized bone allotransplants is enhanced by angiogenic cytokine delivery, with results using FGF2 that are comparable to isotransplant from previous studies. Further studies are needed to achieve bone formation similar to isotransplants.
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Affiliation(s)
- Mikko Larsen
- Department of Orthopedic Surgery, Microvascular Research Laboratory, Mayo Clinic, Rochester, MN
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