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Hu K, Sun H, Gui B, Sui C. Gremlin-1 suppression increases BMP-2-induced osteogenesis of human mesenchymal stem cells. Mol Med Rep 2017; 15:2186-2194. [PMID: 28260028 PMCID: PMC5364878 DOI: 10.3892/mmr.2017.6253] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 01/23/2017] [Indexed: 01/06/2023] Open
Abstract
Previous research focusing on rodent cells and animal models has demonstrated that gremlin-1 antagonizes bone morphogenetic proteins (BMPs) in order to suppress osteogenesis. However, the impact of gremlin-1 on osteogenesis in human bone marrow-derived mesenchymal stem cells (MSCs) remains unknown. The aim of the present study was to test the effects of gremlin-1 on viability and in vitro BMP-2-induced osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (MSCs). Gremlin-1-specific small interfering RNA (siRNA) inhibited gremlin-1 mRNA and protein expression in human MSCs. The mRNA expression levels of osteoblastic genes were analyzed using reverse transcription-quantitative polymerase chain reaction, and calcification and enzymatic alkaline phosphatase (ALP) activity assessed the BMP-2-induced osteogenic differentiation of human MSCs. The results indicated that gremlin-1 suppression significantly increased human MSC metabolism and DNA content. The expression levels of osteoblastic genes were also significantly increased by gremlin-1 inhibition. In the gremlin-1-inhibited group, enzymatic ALP activity was significantly increased. In addition, due to BMP-2-inducing osteoblasts, gremlin-1 inhibition increased calcium deposits. The present study indicated that gremlin-1 inhibited the cell viability and osteogenic differentiation of human MSCs and that the suppression of gremlin-1 expression suppressed can increase the cell viability and osteogenic differentiation of human MSCs induced by BMP-2.
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Affiliation(s)
- Kongzu Hu
- Department of Orthopaedics, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230032, P.R. China
| | - Heyan Sun
- Department of Orthopaedics, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230032, P.R. China
| | - Binjie Gui
- Department of Orthopaedics, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230032, P.R. China
| | - Cong Sui
- Department of Orthopaedics, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230032, P.R. China
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Tsuchiya S, Chiba M, Kishimoto KN, Nakamura H, Tsuchiya M, Hayashi H. Transfer of the bone morphogenetic protein 4 gene into rat periodontal ligament by in vivo electroporation. Arch Oral Biol 2016; 74:123-132. [PMID: 27940045 DOI: 10.1016/j.archoralbio.2016.11.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 10/07/2016] [Accepted: 11/22/2016] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Regulation of alveolar bone metabolism is required in clinical dentistry. The aim of the present study was to establish a method for gene transfer into the periodontal ligament (PDL) by in vivo electroporation with a plasmid vector and to investigate the effects of BMP-4 transfer into the PDL. DESIGN Plasmids containing mouse BMP-4 cDNA (pCAGGS-BMP4) were transfected into cultured rat PDL cells by in vitro electroporation, and BMP-4 production and secretion were detected by immunocytochemistry and western blotting. Next, pCAGGS-BMP4 was injected into the PDL of rats, and electroporation was performed in vivo, using original paired-needle electrodes. BMP-4 expression was examined by immunohistochemical staining 3, 7, 14, 21, and 28days after electroporation. Control groups were injected with pCAGGS by electroporation, injected with pCAGGS-BMP4 without electroporation, or subjected to neither injection nor electroporation. RESULTS In vitro-transfected rat PDL cells exhibited production and secretion of the mature-form BMP-4. After in vivo electroporation of pCAGGS-BMP4, site-specific BMP-4 expression peaked on day 3, gradually decreased until day 14, and was absent by day 21. We observed no unfavorable effects such as inflammation, degeneration, or necrosis. CONCLUSIONS Gene transfer by electroporation with plasmid DNA vectors has several advantages over other methods, including the non-viral vector, non-immunogenic effects, site-specific expression, simplicity, cost-effectiveness, and limited histological side effects. Our results indicate that the method is useful for gene therapy targeting the periodontal tissue, which regulates alveolar bone remodeling.
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Affiliation(s)
- Shinobu Tsuchiya
- Division of Oral Dysfunction Science, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Miyagi, 980-8575, Japan.
| | - Mirei Chiba
- Division of Oral Physiology, Department of Oral Function and Morphology, Tohoku University Graduate School of Dentistry, Miyagi, 980-8575, Japan.
| | - Koshi N Kishimoto
- Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, Miyagi, 980-8575, Japan.
| | - Harukazu Nakamura
- Department of Molecular Neurobiology, Tohoku University Graduate School of Life Sciences and Institute of Development, Aging and Cancer, Miyagi, 980-8575, Japan.
| | - Masahiro Tsuchiya
- Faculty of Health Science, Department of Nursing, Tohoku Fukushi University, Miyagi, 981-8522, Japan; Division of Oral Diagnosis, Tohoku University Graduate School of Dentistry, Miyagi, 980-8575, Japan.
| | - Haruhide Hayashi
- Division of Oral Physiology, Department of Oral Function and Morphology, Tohoku University Graduate School of Dentistry, Miyagi, 980-8575, Japan.
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Choi YH, Kim GS, Choi JH, Jin SW, Kim HG, Han Y, Lee DY, Choi SI, Kim SY, Ahn YS, Lee KY, Jeong HG. Ethanol extract of Lithospermum erythrorhizon Sieb. et Zucc. promotes osteoblastogenesis through the regulation of Runx2 and Osterix. Int J Mol Med 2016; 38:610-8. [PMID: 27353217 DOI: 10.3892/ijmm.2016.2655] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 06/16/2016] [Indexed: 02/04/2023] Open
Abstract
Bone remodeling and homeostasis are largely the result of the coordinated action of osteoblasts and osteoclasts. Osteoblasts are responsible for bone formation. The differentiation of osteoblasts is regulated by the transcription factors, Runx2 and Osterix. Natural products of plant origin are still a major part of traditional medicinal systems in Korea. The root of Lithospermum erythrorhizon Sieb. et Zucc. (LR), the purple gromwell, is an herbal medicine used for inflammatory and infectious diseases. LR is an anti-inflammatory and exerts anticancer effects by inducing the apoptosis of cancer cells. However, the precise molecular signaling mechanisms of osteoblastogenesis as regards LR and osteoblast transcription are not yet known. In this study, we investigated the effects of ethanol (EtOH) extract of LR (LES) on the osteoblast differentiation of C2C12 myoblasts induced by bone morphogenetic protein 4 (BMP4) and the potential involvement of Runx2 and Osterix in these effects. We found that the LES exhibited an ability to induce osteoblast differentiation. LES increased the expression of the osteoblast marker, alkaline phosphatase (ALP), as well as its activity, as shown by ALP staining and ALP activity assay. LES also increased mineralization, as shown by Alizarin Red S staining. Treatment with LES increased the protein levels (as shown by immunoblotting), as well as the transcriptional activity of Runx2 and Osterix and enhanced osteogenic activity. These results suggest that LES modulates osteoblast differentiation at least in part through Runx2 and Osterix.
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Affiliation(s)
- You Hee Choi
- College of Pharmacy, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Geum Soog Kim
- Department of Herbal Crop Research, National Institute of Horticultural and Herbal Science, RDA, Eumseong 369-873, Republic of Korea
| | - Jae Ho Choi
- College of Pharmacy, Chungnam National University, Daejeon 305-764, Republic of Korea
| | - Sun Woo Jin
- College of Pharmacy, Chungnam National University, Daejeon 305-764, Republic of Korea
| | - Hyung Gyun Kim
- College of Pharmacy, Chungnam National University, Daejeon 305-764, Republic of Korea
| | - Younho Han
- College of Pharmacy, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Dae Young Lee
- Department of Herbal Crop Research, National Institute of Horticultural and Herbal Science, RDA, Eumseong 369-873, Republic of Korea
| | - Soo Im Choi
- YD Global Life Science Co., Ltd., Seongnam 462-807, Republic of Korea
| | - Seung Yu Kim
- Department of Herbal Crop Research, National Institute of Horticultural and Herbal Science, RDA, Eumseong 369-873, Republic of Korea
| | - Young Sup Ahn
- Department of Herbal Crop Research, National Institute of Horticultural and Herbal Science, RDA, Eumseong 369-873, Republic of Korea
| | - Kwang Youl Lee
- College of Pharmacy, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Hye Gwang Jeong
- College of Pharmacy, Chungnam National University, Daejeon 305-764, Republic of Korea
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Kim YD, Pofali P, Park TE, Singh B, Cho K, Maharjan S, Dandekar P, Jain R, Choi YJ, Arote R, Cho CS. Gene therapy for bone tissue engineering. Tissue Eng Regen Med 2016; 13:111-125. [PMID: 30603391 PMCID: PMC6170855 DOI: 10.1007/s13770-016-9063-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 09/24/2015] [Accepted: 09/29/2015] [Indexed: 02/06/2023] Open
Abstract
Gene therapy holds a great promise and has been extensively investigated to improve bone formation and regeneration therapies in bone tissue engineering. A variety of osteogenic genes can be delivered by combining different vectors (viral or non-viral), scaffolds and delivery methodologies. Ex vivo & in vivo gene enhanced tissue engineering approaches have led to successful osteogenic differentiation and bone formation. In this article, we review recent advances of gene therapy-based bone tissue engineering discussing strengths and weaknesses of various strategies as well as general overview of gene therapy.
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Affiliation(s)
- Young-Dong Kim
- Department of Molecular Genetics, School of Dentistry, Seoul National University, Seoul, Korea
| | - Prasad Pofali
- Department of Chemical Engineering, Institute of Chemical Technology, Mumbai, India
| | - Tae-Eun Park
- Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea
| | - Bijay Singh
- Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea
| | - Kihyun Cho
- Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea
| | - Sushila Maharjan
- Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea
| | - Prajakta Dandekar
- Department of Pharmaceutical Sciences and Technology, Institute of Chemical Technology, Mumbai, India
| | - Ratnesh Jain
- Department of Chemical Engineering, Institute of Chemical Technology, Mumbai, India
| | - Yun-Jaie Choi
- Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea
| | - Rohidas Arote
- Department of Molecular Genetics, School of Dentistry, Seoul National University, Seoul, Korea
| | - Chong-Su Cho
- Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea
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Heterotopic bone formation about the hip undergoes endochondral ossification: a rabbit model. Clin Orthop Relat Res 2013; 471:1584-92. [PMID: 23361932 PMCID: PMC3613540 DOI: 10.1007/s11999-013-2801-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 01/11/2013] [Indexed: 01/31/2023]
Abstract
BACKGROUND Heterotopic ossification (HO) occurs most commonly after trauma and surgery about the hip and may compromise subsequent function. Currently available animal models describing the cellular progression of HO are based on exogenous osteogenic induction agents and may not reflect the processes following trauma. QUESTIONS/PURPOSES We therefore sought to characterize the histologic progression of heterotopic bone formation in an animal model that recapitulates the human condition without the addition of exogenous osteogenic material. METHODS We used a rabbit model that included intramedullary instrumentation of the upper femur and ischemic crush injury of the gluteal muscle. Bilateral surgical induction procedures were performed on 30 animals with the intention of inciting the process of HO; no supplemental osteogenic stimulants were used. Three animals were sacrificed at each of 10 predetermined times between 1 day and 26 weeks postoperatively and the progression of tissue maturation was graded histologically using a five-item scale. RESULTS Heterotopic bone reliably formed de novo and consistently followed a pathway of endochondral ossification. Chondroid elements were found in juxtaposition with immature woven bone in all sections that contained mature osseous elements. CONCLUSIONS These results establish that HO occurs in an animal model mimicking the human condition following surgical trauma about the hip; it is predictable in its histologic progression and follows a pathway of endochondral bone formation. CLINICAL RELEVANCE By showing a consistent pathway of endochondral ossification leading to ectopic bone formation, this study provides a basis for understanding the mechanisms by which HO might be mitigated by interventions.
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Im GI. Nonviral gene transfer strategies to promote bone regeneration. J Biomed Mater Res A 2013; 101:3009-18. [PMID: 23554051 DOI: 10.1002/jbm.a.34576] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 01/02/2013] [Indexed: 11/10/2022]
Abstract
Despite the inherent ability of bone to regenerate itself, there are a number of clinical situations in which complete bone regeneration fails to occur. In view of shortcomings of conventional treatment, gene therapy may have a place in cases of critical-size bone loss that cannot be properly treated with current medical or surgical treatment. The purpose of this review is to provide an overview of gene therapy in general, nonviral techniques of gene transfer including physical and chemical methods, RNA-based therapy, therapeutic genes to be transferred for bone regeneration, route of application including ex vivo application, and direct gene therapy approaches to regenerate bone.
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Affiliation(s)
- Gun-Il Im
- Department of Orthopaedics, Dongguk University Ilsan Hospital, Korea
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7
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Gene therapy approaches to regenerating bone. Adv Drug Deliv Rev 2012; 64:1320-30. [PMID: 22429662 DOI: 10.1016/j.addr.2012.03.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 02/13/2012] [Accepted: 03/05/2012] [Indexed: 02/07/2023]
Abstract
Bone formation and regeneration therapies continue to require optimization and improvement because many skeletal disorders remain undertreated. Clinical solutions to nonunion fractures and osteoporotic vertebral compression fractures, for example, remain suboptimal and better therapeutic approaches must be created. The widespread use of recombinant human bone morphogenetic proteins (rhBMPs) for spine fusion was recently questioned by a series of reports in a special issue of The Spine Journal, which elucidated the side effects and complications of direct rhBMP treatments. Gene therapy - both direct (in vivo) and cell-mediated (ex vivo) - has long been studied extensively to provide much needed improvements in bone regeneration. In this article, we review recent advances in gene therapy research whose aims are in vivo or ex vivo bone regeneration or formation. We examine appropriate vectors, safety issues, and rates of bone formation. The use of animal models and their relevance for translation of research results to the clinical setting are also discussed in order to provide the reader with a critical view. Finally, we elucidate the main challenges and hurdles faced by gene therapy aimed at bone regeneration as well as expected future trends in this field.
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Scott MA, Levi B, Askarinam A, Nguyen A, Rackohn T, Ting K, Soo C, James AW. Brief review of models of ectopic bone formation. Stem Cells Dev 2012; 21:655-67. [PMID: 22085228 DOI: 10.1089/scd.2011.0517] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Ectopic bone formation is a unique biologic entity--distinct from other areas of skeletal biology. Animal research models of ectopic bone formation most often employ rodent models and have unique advantages over orthotopic (bone) environments, including a relative lack of bone cytokine stimulation and cell-to-cell interaction with endogenous (host) bone-forming cells. This allows for relatively controlled in vivo experimental bone formation. A wide variety of ectopic locations have been used for experimentation, including subcutaneous, intramuscular, and kidney capsule transplantation. The method, benefits and detractions of each method are summarized in the following review. Briefly, subcutaneous implantation is the simplest method. However, the most pertinent concern is the relative paucity of bone formation in comparison to other models. Intramuscular implantation is also widely used and relatively simple, however intramuscular implants are exposed to skeletal muscle satellite progenitor cells. Thus, distinguishing host from donor osteogenesis becomes challenging without cell-tracking studies. The kidney capsule (perirenal or renal capsule) method is less widely used and more technically challenging. It allows for supraphysiologic blood and nutrient resource, promoting robust bone growth. In summary, ectopic bone models are extremely useful in the evaluation of bone-forming stem cells, new osteoinductive biomaterials, and growth factors; an appropriate choice of model, however, will greatly increase experimental success.
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Affiliation(s)
- Michelle A Scott
- Orthodontics and Dentofacial Orthopedics, Roseman University of Health Sciences, Henderson, Nevada, USA
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Pelled G, Ben-Arav A, Hock C, Reynolds DG, Yazici C, Zilberman Y, Gazit Z, Awad H, Gazit D, Schwarz EM. Direct gene therapy for bone regeneration: gene delivery, animal models, and outcome measures. TISSUE ENGINEERING PART B-REVIEWS 2010; 16:13-20. [PMID: 20143927 DOI: 10.1089/ten.teb.2009.0156] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
While various problems with bone healing remain, the greatest clinical change is the absence of an effective approach to manage large segmental defects in limbs and craniofacial bones caused by trauma or cancer. Thus, nontraditional forms of medicine, such as gene therapy, have been investigated as a potential solution. The use of osteogenic genes has shown great potential in bone regeneration and fracture healing. Several methods for gene delivery to the fracture site have been described. The majority of them include a cellular component as the carrying vector, an approach known as cell-mediated gene therapy. Yet, the complexity involved with cell isolation and culture emphasizes the advantages of direct gene delivery as an alternative strategy. Here we review the various approaches of direct gene delivery for bone repair, the choice of animal models, and the various outcome measures required to evaluate the efficiency and safety of each technique. Special emphasis is given to noninvasive, quantitative, in vivo monitoring of gene expression and biodistribution in live animals. Research efforts should aim at inducing a transient, localized osteogenic gene expression within a fracture site to generate an effective therapeutic approach that would eventually lead to clinical use.
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Affiliation(s)
- Gadi Pelled
- Skeletal Biotechnology Laboratory, Hebrew University of Jerusalem-Hadassah Medical Campus, Jerusalem, Israel
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Pelled G, Ben-Arav A, Hock C, Reynolds DG, Yazici C, Zilberman Y, Gazit Z, Awad H, Gazit D, Schwarz EM. Direct Gene Therapy for Bone Regeneration: Gene Delivery, Animal Models, and Outcome Measures. Tissue Eng Part A 2009. [DOI: 10.1089/ten.tea.2009.0156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Watanuki M, Kishimoto KN, Kotajima S, Iwabuchi S, Kokubun S. Effect of low-intensity pulsed ultrasound on scaffold-free ectopic bone formation in skeletal muscle. Ups J Med Sci 2009; 114:242-8. [PMID: 19961269 PMCID: PMC2852778 DOI: 10.3109/03009730903226659] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Low-intensity pulsed ultrasound (LIPUS) is reported to have the effects of rapid appearance and early maturation of ossification in animal models. METHOD We examined the influence of LIPUS on bone formation in C57BL/6J mouse muscle induced by gene transfer of BMP-4 expression plasmid. Electroporation was employed to transfer plasmid DNA. First, an in vitro study was carried out to confirm that LIPUS has no effect on the forced expression of BMP-4 gene transferred by electroporation into C2C12 cells. Next, the BMP-4 plasmids were injected into mouse calf muscles, and transcutaneous electroporation was applied. LIPUS (30 mW/cm(2)) exposure was performed daily for 20 minutes on one side of hind limbs (LIPUS side). The contralateral limbs were not exposed to LIPUS (control side). Muscle samples were collected at 7, 10, 14, and 21 days after electroporation. Soft X-ray films of muscles were taken, and areas of bone formation were measured. After pepsin solubilization of the muscles, calcium and total collagen content were measured. RESULTS Radiographical measurements showed significantly more bone formation in the LIPUS side at Day 10. The area of bone was the maximum in both sides at Day 14. The LIPUS side exhibited significant increase in the calcium content at Day 10. The total collagen content with LIPUS exposure was increased significantly over control at Day 10 and 21. CONCLUSIONS According to these results, accelerated maturation of ectopic bone formation by LIPUS was confirmed at Day 10. Moreover, our results showed that LIPUS increases the total collagen content during osteogenesis.
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Affiliation(s)
- Munenori Watanuki
- Department of Orthopaedic Surgery, Tohoku University School of Medicine, SendaiJapan
| | - Koshi N. Kishimoto
- Department of Orthopaedic Surgery, Tohoku University School of Medicine, SendaiJapan
| | - Satoshi Kotajima
- Department of Orthopaedic Surgery, Tohoku University School of Medicine, SendaiJapan
| | - Sadahiro Iwabuchi
- Bio-medical Engineering Laboratories, Teijin Pharma Ltd., TokyoJapan
| | - Shoichi Kokubun
- Department of Orthopaedic Surgery, Tohoku University School of Medicine, SendaiJapan
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Huang Z, Nelson ER, Smith RL, Goodman SB. The sequential expression profiles of growth factors from osteoprogenitors [correction of osteroprogenitors] to osteoblasts in vitro. ACTA ACUST UNITED AC 2007; 13:2311-20. [PMID: 17523879 DOI: 10.1089/ten.2006.0423] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In this study, we delineate the sequential expression of selected growth factors associated with bone formation in vitro. Mineralization, osteocalcin, and alkaline phosphatase (ALP-2) were measured to monitor the differentiation and maturation of osteoprogenitor cells collected from C57BL mice. Bone-related growth factors, including transforming growth factor beta (TGF-beta), fibroblast growth factor 2 (FGF-2), platelet-derived growth factor (PDGF), insulinlike growth factor (IGF)-1, vascular endothelial growth factor (VEGF), bone morphogenetic protein (BMP)-2, and BMP-7, were selected. Enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR) were used to measure growth factors at the protein and messenger ribonucleic acid (mRNA) level, respectively. The results found that ALP-2 expression increased progressively over time, whereas mineralization and osteocalcin did not become evident until culture day 14. VEGF and IGF-1 were upregulated early during proliferation. PDGF and TGF-beta mRNA expression was bimodal. FGF-2 and BMP-2 mRNAs were expressed only later in differentiation. FGF-2 mRNA signal levels were highest at day 14 and remained prominent through day 28 of culture. BMP-2 showed a similar profile as FGF-2. BMP-7 was not detectable using RT-PCR or ELISA. Strong correlations existed for the expression patterns between several early-response growth factors (VEGF, TGF-beta, and IGF-1) and were also evident for several late-response growth factors (BMP-2, PDGF, and FGF-2). Differential expression for grouped sets of growth factors occurs during the temporal acquisition of bone-specific markers as osteoprogenitor cell maturation proceeds in vitro.
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Affiliation(s)
- Zhinong Huang
- Department of Orthopedic Surgery, Stanford University Medical Center, Stanford, California 94305, USA
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