Publications by authors named "David N Paglia"

19 Publications

  • Page 1 of 1

Naproxen treatment inhibits articular cartilage loss in a rat model of osteoarthritis.

J Orthop Res 2020 Dec 4. Epub 2020 Dec 4.

Department of Orthopaedics, Rutgers-New Jersey Medical School, Newark, New Jersey, USA.

The effects of naproxen, a nonsteroidal anti-inflammatory drug (NSAID), on articular cartilage degeneration in female Sprague-Dawley rats was examined. Osteoarthritis (OA) was induced by destabilization of the medial meniscus (DMM) in each knee. Rats were treated with acetaminophen (60 mg/kg), naproxen (8 mg/kg), or 1% carboxymethylcellulose (placebo) by oral gavage twice daily for 3 weeks, beginning 2 weeks after surgery. OA severity was assessed by histological Osteoarthritis Research Society International (OARSI) scoring and by measuring proximal tibia cartilage depth using contrast enhanced µCT (n = 6 per group) in specimens collected at 2, 5, and 7 weeks after surgery as well as on pristine knees. Medial cartilage OARSI scores from the DMM knees of naproxen-treated rats were statistically lower (i.e., better) than the medial cartilage OARSI scores from the DMM knees of placebo-treated rats at 5-weeks (8.7 ± 3.6 vs. 13.2 ± 2.4, p = 0.025) and 7-weeks (9.5 ± 1.2 vs. 12.5 ± 2.5, p = 0.024) after surgery. At 5 weeks after DMM surgery, medial articular cartilage depth in the proximal tibia specimens was significantly greater in the naproxen (1.78 ± 0.26 mm, p = 0.005) and acetaminophen (1.94 ± 0.12 mm, p < 0.001) treated rats as compared with placebo-treated rats (1.34 ± 0.24 mm). However, at 7 weeks (2 weeks after drug withdrawal), medial articular cartilage depth for acetaminophen-treated rats (1.36 ± 0.29 mm) was significantly reduced compared with specimens from the naproxen-treated rats (1.88 ± 0.14 mm; p = 0.004). The results indicate that naproxen treatment reduced articular cartilage degradation in the rat DMM model during and after naproxen treatment.
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http://dx.doi.org/10.1002/jor.24937DOI Listing
December 2020

Deletion of Wnt5a in osteoclasts results in bone loss through decreased bone formation.

Ann N Y Acad Sci 2020 03 9;1463(1):45-59. Epub 2020 Jan 9.

Department of Orthopaedics, Emory University School of Medicine, Atlanta, Georgia.

Bone remodeling is achieved through the coupled activities of osteoclasts and osteoblasts that are controlled by many locally generated secreted factors, including WNT5A. While previous studies have demonstrated that osteoblast-derived WNT5A promotes osteoclastogenesis, the function of osteoclast-derived WNT5A on bone remodeling has remained unexplored. We examined the effects of osteoclast-derived WNT5A on bone homeostasis by utilizing the Cathepsin K-Cre (Ctsk-Cre) mouse to conditionally delete Wnt5a in mature osteoclasts. These mice exhibited reduced trabecular and cortical bone. The low bone-mass phenotype was driven by decreased bone formation, not osteoclast-mediated bone resorption, as osteoclast number and serum CTX marker were unchanged. Furthermore, molecular analysis of osteoclast- and osteoblast-derived WNT5A identified a serine-phosphorylated WNT5A that is unique to RANKL-treated macrophages mimicking osteoclasts. This study suggests a new paradigm in which WNT5A has opposing effects on bone remodeling that are dependent on the cell of origin, an effect that may result from cell type-specific differential posttranslational modifications of WNT5A.
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http://dx.doi.org/10.1111/nyas.14293DOI Listing
March 2020

Deletion of Runx1 in osteoclasts impairs murine fracture healing through progressive woven bone loss and delayed cartilage remodeling.

J Orthop Res 2020 05 3;38(5):1007-1015. Epub 2019 Dec 3.

Department of Orthopaedics, School of Medicine, Emory University, Atlanta, Georgia.

Conditional deletion of the transcription factor Runt-related transcription factor 1 (Runx1) in myeloid osteoclast precursors promotes osteoclastogenesis and subsequent bone loss. This study posits whether Runx1 regulates clastic cell-mediated bone and cartilage resorption in the fracture callus. We first generated mice, in which Runx1 was conditionally abrogated in osteoclast precursors (LysM-Cre;Runx1 ; Runx1 cKO). Runx1 cKO and control mice were then subjected to experimental mid-diaphyseal femoral fractures. Our study found differential resorption of bony and calcified cartilage callus matrix by osteoclasts and chondroclasts within Runx1 cKO calluses, with increased early bony callus resorption and delayed calcified cartilage resorption. There was an increased number of osteoclasts and chondroclasts in the chondro-osseous junction of Runx1 cKO calluses starting at day 11 post-fracture, with minimal woven bone occupying the callus at day 18 post-fracture. LysM-Cre;Runx1 mutant mice had increased bone compliance at day 28, but their strength and work to failure were comparable with controls. Taken together, these results indicate that Runx1 is a critical transcription factor in controlling osteoclastogenesis that negatively regulates bone and cartilage resorption in the fracture callus. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:1007-1015, 2020.
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http://dx.doi.org/10.1002/jor.24537DOI Listing
May 2020

Articular cartilage protection in Ctsk mice is associated with cellular and molecular changes in subchondral bone and cartilage matrix.

J Cell Physiol 2018 11 21;233(11):8666-8676. Epub 2018 May 21.

Department of Orthopaedics, Emory University, Atlanta, Georgia.

Osteoarthritis (OA) is a degenerative disease and a major cause of chronic disability in aging individuals. Cathepsin K (CatK), encoded by the Ctsk gene, has been implicated in the pathogenesis of pycnodysostosis and osteoporosis. The use of a selective inhibitor of CatK was recently shown to delay OA progression in rabbits. However, the cellular mechanisms underlying these protective effects remain unexplored. We examined articular cartilage maintenance and joint bone remodeling using Ctsk null mice (Ctsk ) which underwent destabilization of the medial meniscus (DMM). We found that Ctsk mice displayed delayed remodeling of subchondral and calcified cartilage by osteoclasts and chodroclasts respectively in DMM-induced osteoarthritis. While WT mice displayed a more severe OA phenotype than Ctsk mice at 16 weeks, higher subchondral bone volume and lower trabecular spacing were also observed in surgically-induced OA joints of Ctsk mice. However, no differences were seen in non-surgical controls. During OA progression, TRAP osteoclast numbers were increased in both WT and Ctsk mice. However, Ctsk mice had fewer physis-derived chondroclasts than WT when OA was present. These data suggest that CatK may differentially regulate chondroclastogenesis in the growth plate. Targeted PCR arrays of RNA harvested from laser captured osteoclasts in the subchondral bone and chondroclasts in the growth plate demonstrated differential expression of Atp6v0d2, Tnfrsf11a, Ca2, Calcr, Ccr1, Gpr68, Itgb3, Nfatc1, and Syk genes between WT and Ctsk mice at 8- and 16-weeks post-DMM. Our data provide insight into the cellular mechanisms by which cathepsin K deletion delays OA progression in mice.
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http://dx.doi.org/10.1002/jcp.26745DOI Listing
November 2018

Transcriptional Mechanisms of Secondary Fracture Healing.

Curr Osteoporos Rep 2018 04;16(2):146-154

Department of Orthopaedics, School of Medicine, Emory University, Atlanta, GA, USA.

Purpose Of Review: Growing evidence supports the critical role of transcriptional mechanisms in promoting the spatial and temporal progression of bone healing. In this review, we evaluate and discuss new transcriptional and post-transcriptional regulatory mechanisms of secondary bone repair, along with emerging evidence for epigenetic regulation of fracture healing.

Recent Findings: Using the candidate gene approach has identified new roles for several transcription factors in mediating the reactive, reparative, and remodeling phases of fracture repair. Further characterization of the different epigenetic controls of fracture healing and fracture-driven transcriptome changes between young and aged fracture has identified key biological pathways that may yield therapeutic targets. Furthermore, exogenously delivered microRNA to post-transcriptionally control gene expression is quickly becoming an area with great therapeutic potential. Activation of specific transcriptional networks can promote the proper progression of secondary bone healing. Targeting these key factors using small molecules or through microRNA may yield effective therapies to enhance and possibly accelerate fracture healing.
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http://dx.doi.org/10.1007/s11914-018-0429-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6262839PMC
April 2018

Regeneration of Articular Cartilage by Human ESC-Derived Mesenchymal Progenitors Treated Sequentially with BMP-2 and Wnt5a.

Stem Cells Transl Med 2017 01 5;6(1):40-50. Epub 2016 Aug 5.

Department of Orthopaedic Surgery, UConn Musculoskeletal Institute, UConn Stem Cell Institute, UConn Health, University of Connecticut, Farmington, Connecticut, USA.

The success of cell-based therapies to restore joint cartilage requires an optimal source of reparative progenitor cells and tight control of their differentiation into a permanent cartilage phenotype. Bone morphogenetic protein 2 (BMP-2) has been extensively shown to promote mesenchymal cell differentiation into chondrocytes in vitro and in vivo. Conversely, developmental studies have demonstrated decreased chondrocyte maturation by Wingless-Type MMTV Integration Site Family, Member 5A (Wnt5a). Thus, we hypothesized that treatment of human embryonic stem cell (hESC)-derived chondroprogenitors with BMP-2 followed by Wnt5a may control the maturational progression of these cells into a hyaline-like chondrocyte phenotype. We examined the effects of sustained exposure of hESC-derived mesenchymal-like progenitors to recombinant Wnt5a or BMP-2 in vitro. Our data indicate that BMP-2 promoted a strong chondrogenic response leading to terminal maturation, whereas recombinant Wnt5a induced a mild chondrogenic response without promoting hypertrophy. Moreover, Wnt5a suppressed BMP-2-mediated chondrocyte maturation, preventing the formation of fibrocartilaginous tissue in high-density cultures treated sequentially with BMP-2 and Wnt5a. Implantation of scaffoldless pellets of hESC-derived chondroprogenitors pretreated with BMP-2 followed by Wnt5a into rat chondral defects induced an articular-like phenotype in vivo. Together, the data establish a novel role for Wnt5a in controlling the progression from multipotency into an articular-like cartilage phenotype in vitro and in vivo. Stem Cells Translational Medicine 2017;6:40-50.
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http://dx.doi.org/10.5966/sctm.2016-0020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5442752PMC
January 2017

Runx1 Regulates Myeloid Precursor Differentiation Into Osteoclasts Without Affecting Differentiation Into Antigen Presenting or Phagocytic Cells in Both Males and Females.

Endocrinology 2016 08 6;157(8):3058-69. Epub 2016 Jun 6.

Departments of Orthopaedic Surgery (D.N.P., X.Y., H.D., J.L.), Medicine (J.K., S.J., J.L.), and Genetics and Genome Sciences (H.D.), University of Connecticut Health, Farmington, Connecticut 06030.

Runt-related transcription factor 1 (Runx1), a master regulator of hematopoiesis, is expressed in preosteoclasts. Previously we evaluated the bone phenotype of CD11b-Cre Runx1(fl/fl) mice and demonstrated enhanced osteoclasts and decreased bone mass in males. However, an assessment of the effects of Runx1 deletion in female osteoclast precursors was impossible with this model. Moreover, the role of Runx1 in myeloid cell differentiation into other lineages is unknown. Therefore, we generated LysM-Cre Runx1(fl/fl) mice, which delete Runx1 equally (∼80% deletion) in myeloid precursor cells from both sexes and examined the capacity of these cells to differentiate into osteoclasts and phagocytic and antigen-presenting cells. Both female and male LysM-Cre Runx1(fl/fl) mice had decreased trabecular bone mass (72% decrease in bone volume fraction) and increased osteoclast number (2-3 times) (P < .05) without alteration of osteoblast histomorphometric indices. We also demonstrated that loss of Runx1 in pluripotential myeloid precursors with LysM-Cre did not alter the number of myeloid precursor cells in bone marrow or their ability to differentiate into phagocytizing or antigen-presenting cells. This study demonstrates that abrogation of Runx1 in multipotential myeloid precursor cells significantly and specifically enhanced the ability of receptor activator of nuclear factor-κB ligand to stimulate osteoclast formation and fusion in female and male mice without affecting other myeloid cell fates. In turn, increased osteoclast activity in LysM-Cre Runx1(fl/fl) mice likely contributed to a decrease in bone mass. These dramatic effects were not due to increased osteoclast precursors in the deleted mutants and argue that inhibition of Runx1 in multipotential myeloid precursor cells is important for osteoclast formation and function.
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http://dx.doi.org/10.1210/en.2015-2037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4967120PMC
August 2016

PDGF-BB Delays Degeneration of the Intervertebral Discs in a Rabbit Preclinical Model.

Spine (Phila Pa 1976) 2016 Apr;41(8):E449-58

From the UConn Health Center, Department of Orthopaedic Surgery, Farmington, CT.

Study Design: Preclinical animal study.

Objective: Determine the in vivo effects of platelet-derived growth factor BB (PDGF-BB) delivered in a thiol-modified hyaluronic acid (TMHA) hydrogel on intervertebral disk (IVD) degeneration.

Summary Of Background Data: IVD degeneration is a worldwide health concern and remains without an effective treatment. Several in vitro studies have demonstrated the potential of PDGF-BB, a primary component of platelet-rich plasma, as a therapy for IVD degeneration. Our hypotheses were that treatment of injured IVDs with PDGF would inhibit degeneration and that administration of PDGF in a TMHA hydrogel would improve its efficacy.

Methods: IVD degeneration was induced using the rabbit annular puncture model. Four weeks after injury, IVDs were treated with either PDGF-BB or PDGF-BB delivered within a TMHA hydrogel. The efficacy of treatment was determined using x-ray, MRI, histology, and biomechanical testing.

Results: At 4 weeks after treatment, cell apoptosis and deposition of matrix containing type III collagen a1 (Col3a1) was demonstrated in both the nucleus pulposus and annulus fibrosus, while this was inhibited by PDGF. At 8 weeks after treatment, disc area and MRI indices of injured IVDs treated with PDGF were significantly higher (P < 0.05) than those treated with the TMHA alone. Similarly, degenerative scores for saline- and TMHA-treated IVDs demonstrated significantly more degeneration (P < 0.05) than PDGF-treated IVDs at 8 weeks. Biomechanical assessments found fewer indicators of degeneration in PDGF-TMHA-treated IVDs at both 4 and 8 weeks post-treatment, compared to saline-, TMHA-, and PDGF-only-treated IVDs. Both PDGF- and PDGF-TMHA-treated IVDs also demonstrated a significant increase (P < 0.05) in compressive strength to failure, compared with controls at 8 weeks post-treatment.

Conclusion: The results of this study suggest that PDGF-BB significantly decreases disc degeneration and when delivered in a TMHA gel scaffold, helps prevent both apoptosis and Col3 matrix production, while maintaining disc structure and biomechanical function.

Level Of Evidence: NA.
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http://dx.doi.org/10.1097/BRS.0000000000001336DOI Listing
April 2016

Constructing the toolbox: Patient-specific genetic factors of altered fracture healing.

Genes Dis 2014 Dec;1(2):140-148

New England Musculoskeletal Institute and Department of Orthopaedic Surgery.

The multifaceted sequence of events that follow fracture repair can be further complicated when considering risk factors for impaired union, present in a large and growing percentage of the population. Risk factors such as diabetes, substance abuse, and poor nutrition affect both the young and old alike, and have been shown to dramatically impair the body's natural healing processes. To this end, biotherapeudic interventions such as ultrasound, electrical simulation, growth factor treatment (BMP-2, BMP-7, PDGF-BB, FGF-2) have been evaluated in preclinical models and in some cases are used widely for patients with established non-union or risk/indication or impaired healing (ie. ultrasound, BMP-2, etc.). Despite the promise of these interventions, they have been shown to be reliant on patient compliance and can produce adverse side-effects such as heterotopic ossification. Gene and cell therapy approaches have attempted to apply controlled regimens of these factors and have produced promising results. However, there are safety and efficacy concerns that may limit the translation of these approaches. In addition, none of the above mentioned approaches consider genetic variation between individual patients. Several clinical and preclinical studies have demonstrated a genetic component to fracture repair and that SNPs and genetic background variation play major roles in the determination of healing outcomes. Despite this, there is a need for preclinical data to dissect the mechanism underlying the influence of specific gene loci on the processes of fracture healing, which will be paramount in the future of patient-centered interventions for fracture repair.
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http://dx.doi.org/10.1016/j.gendis.2014.07.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4280851PMC
December 2014

The effect of locally delivered recombinant human bone morphogenetic protein-2 with hydroxyapatite/tri-calcium phosphate on the biomechanical properties of bone in diabetes-related osteoporosis.

J Orthop Traumatol 2015 Jun 25;16(2):151-9. Epub 2014 Nov 25.

Division of Orthopaedic Trauma, Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, 301 E 17th Street, Suite 1402, New York, NY, 10003, USA,

Background: Recombinant human bone morphogenetic protein-2 (rhBMP-2) is particularly effective in improving osteogenesis in patients with diminished bone healing capabilities, such as individuals with type 1 diabetes mellitus (T1DM) who have impaired bone healing capabilities and increased risk of developing osteoporosis. This study measured the effects of rhBMP-2 treatment on osteogenesis by observing the dose-dependent effect of localized delivery of rhBMP-2 on biomechanical parameters of bone using a hydroxyapatite/tri-calcium phosphate (HA/TCP) carrier in a T1DM-related osteoporosis animal model.

Materials And Methods: Two different doses of rhBMP-2 (LD low dose, HD high dose) with a HA/TCP carrier were injected into the femoral intramedullary canal of rats with T1DM-related osteoporosis. Two more diabetic rat groups were injected with saline alone and with HA/TCP carrier alone. Radiographs and micro-computed tomography were utilized for qualitative assessment of bone mineral density (BMD). Biomechanical testing occurred at 4- and 8-week time points; parameters tested included torque to failure, torsional rigidity, shear stress, and shear modulus.

Results: At the 4-week time point, the LD and HD groups both exhibited significantly higher BMD than controls; at the 8-week time point, the HD group exhibited significantly higher BMD than controls. Biomechanical testing revealed dose-dependent, higher trends in all parameters tested at the 4- and 8-week time points, with minimal significant differences.

Conclusions: Groups treated with rhBMP-2 demonstrated improved bone mineral density at both 4 and 8 weeks compared to control saline groups, in addition to strong trends towards improvement of intrinsic and extrinsic biomechanical properties when compared to control groups. Data revealed trends toward dose-dependent increases in peak torque, torsional rigidity, shear stress, and shear modulus 4 weeks after rhBMP-2 treatment.

Level Of Evidence: Not applicable.
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http://dx.doi.org/10.1007/s10195-014-0327-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4441641PMC
June 2015

Surgical procedures and experimental outcomes of closed fractures in rodent models.

Methods Mol Biol 2015 ;1226:193-211

Department of Orthopaedic Surgery, New England Musculoskeletal Institute, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT, 06030, USA,

The closed fracture rat model, first described by Bonnarens and Einhorn, has been widely implemented in recent years to characterize various fracture phenotypes and evaluate treatment modalities. Slight modifications in the fixation depth, to reduce surgical error associated with movement/dislocation of the k-wire fixation, were previously described. Here, we describe this method which involves the creation of a medial parapatellar incision, dislocation of the patella, boring an 18 gauge hole through the center of the femur, delivery of an adjunct (if applicable), fixation of the k-wire in the greater trochanter of the femur, suturing of muscle and skin, and finally creation of the mid-diaphyseal fracture with a three-point bending fracture device. Many laboratories routinely perform surgical procedures in which a closed fracture is induced using rat or mouse models. The benefits of such surgical models range from general orthopaedic trauma applications to the assessment of the healing process in genetically modified animals. Other important applications include the assessment of the safety and efficacy of various treatment modalities as well as the characterization of bone repair in metabolic bone diseases or skeletal dysplasia.
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http://dx.doi.org/10.1007/978-1-4939-1619-1_15DOI Listing
June 2015

Local manganese chloride treatment accelerates fracture healing in a rat model.

J Orthop Res 2015 Jan 17;33(1):122-30. Epub 2014 Sep 17.

Department of Orthopaedics, Rutgers-New Jersey Medical School, 90 Bergen Street, Suite 7300, Newark, New Jersey, 07103.

This study investigated the effects of local delivery of manganese chloride (MnCl2), an insulin-mimetic compound, upon fracture healing using a rat femoral fracture model. Mechanical testing, histomorphometry, and immunohistochemistry were performed to assess early and late parameters of fracture healing. At 4 weeks post-fracture, maximum torque to failure was 70% higher (P<0.05) and maximum torsional rigidity increased 133% (P<0.05) in animals treated with 0.125 mg/kg MnCl2 compared to saline controls. Histological analysis of the fracture callus revealed percent new mineralized tissue was 17% higher (P<0.05) at day 10. Immunohistochemical analysis of the 0.125 mg/kg MnCl2 treated group, compared to saline controls, showed a 379% increase in the density of VEGF-C+ cells. In addition, compared to saline controls, the 0.125 mg/kg MnCl2 treated group showed a 233% and 150% increase in blood vessel density in the subperiosteal region at day 10 post-fracture as assessed by detection of PECAM and smooth muscle α actin, respectively. The results suggest that local MnCl2 treatment accelerates fracture healing by increasing mechanical parameters via a potential mechanism of amplified early angiogenesis leading to increased osteogenesis. Therefore, local administration of MnCl2 is a potential therapeutic adjunct for fracture healing.
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http://dx.doi.org/10.1002/jor.22733DOI Listing
January 2015

PDGF-BB inhibits intervertebral disc cell apoptosis in vitro.

J Orthop Res 2014 Sep 20;32(9):1181-8. Epub 2014 May 20.

Departments of Orthopaedic Surgery, University of Connecticut Health Center, 263 Farmington Avenue, MARB Building, 4th Floor, Farmington, Connecticut, 06030.

Degeneration of the intervertebral disc (IVD) results in deterioration of the spinal motion segment and can lead to debilitating back pain. Given the established mitotic and anti-apoptotic effects of recombinant human platelet-derived growth factor-BB (rhPDGF-BB) in a variety of cell types we postulated that rhPDGF-BB might delay disc cell degeneration through inhibition of apoptosis. To address this hypothesis, we treated human IVD cells isolated from five independent patients with rhPDGF-BB in monolayer and 3D pellet cultures. The anti-apoptotic potential, cell proliferative capacity, morphology/pellet differentiation, and gene expression of PDGF-treated IVD cells were evaluated via flow cytometry/immunohistochemistry, MTT assays, histology, and quantitative RT-PCR, respectively. We found that rhPDGF-BB treatment significantly inhibited cell apoptosis, increased cell proliferation and matrix production, and maintained mRNA expression of critical extracellular matrix genes. This study suggests two possible mechanisms for the anti-degenerative effects of rhPDGF-BB on human IVD cells. First, PDGF treatment strongly inhibited IVD cell apoptosis in 3D cultures. Second, rhPDGF-BB acts as an anabolic agent, promoting maintenance of IVD cell phenotype in 3D culture, based on the molecular and protein expression analysis. We speculate that rhPDGF-BB may be used as a biologic treatment to target early degenerative IVD disease in the future.
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http://dx.doi.org/10.1002/jor.22638DOI Listing
September 2014

Local ZnCl2 accelerates fracture healing.

J Orthop Res 2014 Jun 26;32(6):834-41. Epub 2014 Feb 26.

Rutgers New Jersey Medical School, Department of Orthopaedics, 90 Bergen Street, Suite 7300, Newark, New Jersey, 07103.

This study evaluated the effect of local zinc chloride (ZnCl2 ), an insulin mimetic agent, upon the early and late parameters of fracture healing in rats using a standard femur fracture model. Mechanical testing, radiographic scoring, histomorphometry, qualitative histological scoring, PCNA immunohistochemistry, and local growth factor analysis were performed. Fractures treated with local ZnCl2 possessed significantly increased mechanical properties compared to controls at 4 weeks post fracture. The radiographic scoring analysis showed increased cortical bridging at 4 weeks in the 1.0 (p=0.0015) and 3.0 (p<0.0001) mg/kg ZnCl2 treated groups. Histomorphometry of the fracture callus at day 7 showed 177% increase (p=0.036) in percent cartilage and 133% increase (p=0.002) in percent mineralized tissue with local ZnCl2 treatment compared to controls. Qualitative histological scoring showed a 2.1× higher value at day 7 in the ZnCl2 treated group compared to control (p = 0.004). Cell proliferation and growth factors, VEGF and IGF-I, within fracture calluses treated with local ZnCl2 were increased at day 7. The results suggest local administration of ZnCl2 increases cell proliferation, causing increased growth factor production which yields improved chondrogenesis and endochondral ossification. Ultimately, these events lead to accelerated fracture healing as early as 4 weeks post fracture.
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http://dx.doi.org/10.1002/jor.22593DOI Listing
June 2014

Local vanadium release from a calcium sulfate carrier accelerates fracture healing.

J Orthop Res 2014 May 30;32(5):727-34. Epub 2013 Dec 30.

Department of Orthopaedics, Rutgers New Jersey Medical School, 90 Bergen Street, Suite 7300, Newark, New Jersey, 07103.

This study evaluated the efficacy of using calcium sulfate (CaSO4 ) as a carrier for intramedullary delivery of an organic vanadium salt, vanadyl acetylacetonate (VAC) after femoral fracture. VAC can act as an insulin-mimetic and can be used to accelerate fracture healing in rats. A heterogenous mixture of VAC and CaSO4 was delivered to the fracture site of BB Wistar rats, and mechanical testing, histomorphometry, micro-computed tomography (micro-CT) were performed to measure healing. At 4 weeks after fracture, maximum torque to failure, effective shear modulus, and effective shear stress were all significantly higher (p < 0.05) in rats treated with 0.25 mg/kg VAC-CaSO4 as compared to carrier control rats. Histomorphometry found a 71% increase in percent cartilage matrix (p < 0.05) and a 64% decrease in percent mineralized tissue (p < 0.05) at 2 weeks after fracture in rats treated with 0.25 mg/kg of VAC-CaSO4 . Micro-CT analyses at 4 weeks found a more organized callus structure and higher trending maximum connected z-ray. fraction for VAC-CaSO4 groups. Evaluation of radiographs and serial histological sections at 12 weeks did not show any evidence of ectopic bone formation. As compared to previous studies, CaSO4 was an effective carrier for reducing the dose of VAC required to accelerate femoral fracture healing in rats.
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http://dx.doi.org/10.1002/jor.22570DOI Listing
May 2014

Effects of Wnt5a Haploinsufficiency on Bone Repair.

J Orthop Trauma 2014 Aug;28(8):e191-7

Department of Orthopaedic Surgery, New England Musculoskeletal Institute, University of Connecticut Health Center, Farmington, CT.

Objectives: Wnt5a expression is upregulated during fracture repair and has previously been implicated as a potential regulator of skeletal development and bone mass accrual and maintenance. Our objective was to evaluate the function of Wnt5a in fracture healing.

Methods: Femoral fracture experiments on Wnt5a and Wnt5a mice were carried out. To better understand the effect of the Wnt5a on bone repair, we evaluated radiographs using a previously validated qualitative scoring system and performed microcomputed tomography analyses. Histomorphometric analyses determined the temporal distribution of stroma, cartilage matrix, and woven bone in the fracture callus. Finally, we performed tartrate-resistant acid phosphatase (TRAP) immunohistochemical staining to visualize and quantify bone resorbing cells.

Results: Radiographic evaluations at day 21 demonstrated significantly higher cortical remodeling and bridging parameters for the Wnt5a group compared with the Wnt5a group. The bone volume fraction by microcomputed tomography was also significantly increased in Wnt5a mice. Histological and histomorphometric analyses showed that although Wnt5a mice exhibit decreased cartilage matrix production at day 7 postfracture, they displayed increased residual cartilaginous callus at days 14 and 21 compared with the Wnt5a group. In addition, the total number of multinucleated tartrate-resistant acid phosphatase-positive cells was significantly lower in the Wnt5a group than in the Wnt5a group.

Conclusions: The data indicate that decreased Wnt5a signaling impaired proper fracture healing, possibly through decreased cartilaginous callus formation, and delayed cartilage matrix and mineralized tissue remodeling within the fracture callus.
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http://dx.doi.org/10.1097/BOT.0000000000000041DOI Listing
August 2014

Effects of local insulin delivery on subperiosteal angiogenesis and mineralized tissue formation during fracture healing.

J Orthop Res 2013 May 13;31(5):783-91. Epub 2012 Dec 13.

Department of Orthopaedics, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, 90 Bergen Street, Suite 7300, Newark, NJ 07103, USA.

Local insulin delivery has been shown to improve osseous healing in diabetic animals. The purpose of this study was to quantify the effects of local intramedullary delivery of saline or Ultralente insulin (UL) on various fracture healing parameters using an in vivo non-diabetic BB Wistar rat model. Quantitation of local insulin levels showed a rapid release of insulin from the fractured femora, demonstrating complete release at 2 days. RT-PCR analysis revealed that the expression of early osteogenic markers (Col1α2, osteopontin) was significantly enhanced with UL treatment when compared with saline controls (p < 0.05). Significant differences in VEGF + cells and vascularity were evident between the treatment and control groups at day 7 (p < 0.05). At day 21, histomorphometric analysis demonstrated a significant increase in percent mineralized tissue in the UL-treated animals compared with controls (p < 0.05), particularly within the subperiosteal region of the fracture callus. Mechanical testing at 4 weeks showed significantly greater mechanical strength for UL-treated animals (p < 0.05), but healing in control animals caught up at 6 weeks post-fracture. These results suggest that the primary osteogenic effect of UL during the early stages of fracture healing (1-3 weeks) is through an increase in osteogenic gene expression, subperiosteal angiogenesis, and mineralized tissue formation.
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http://dx.doi.org/10.1002/jor.22288DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6446235PMC
May 2013

Local insulin therapy affects fracture healing in a rat model.

J Orthop Res 2013 May 13;31(5):776-82. Epub 2012 Dec 13.

Department of Orthopaedics, University of Medicine, Dentistry of New Jersey-New Jersey Medical School, 185 South Orange Avenue, 90 Bergen Street, Suite 7300, Newark, NJ 07103, USA.

A significant number of lower extremity fractures result in mal-union necessitating effective treatments to restore ambulation. Prior research in diabetic animal fracture models demonstrated improved healing following local insulin application to the fracture site and indicated that local insulin therapy can aid bone regeneration, at least within an insulin-dependent diabetic animal model. This study tested whether local insulin therapy could accelerate femur fracture repair in normal, non-diabetic rats. High (20 units) and low (10 units) doses of insulin were delivered in a calcium sulfate carrier which provided sustained release of the exogenous insulin for 7 days after fracture. Histomorphometry, radiographic scoring, and torsional mechanical testing were used to measure fracture healing. The fracture calluses from rats treated with high-dose insulin had significantly more cartilage than untreated rats after 7 and 14 days of healing. After 4 weeks of healing, femurs from rats treated with low-dose insulin had significantly higher radiographic scores and mechanical strength (p < 0.05), compared to the no treatment control groups. The results of this study suggest that locally delivered insulin is a potential therapeutic agent for treating bone fractures. Further studies are necessary, such as large animal proof of concepts, prior to the clinical use of insulin for bone fracture treatment.
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http://dx.doi.org/10.1002/jor.22287DOI Listing
May 2013

The effects of local vanadium treatment on angiogenesis and chondrogenesis during fracture healing.

J Orthop Res 2012 Dec 31;30(12):1971-8. Epub 2012 May 31.

Department of Orthopaedics, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, 90 Bergen Street, Suite 7300, Newark, New Jersey 07103, USA.

This study quantified the effects of local intramedullary delivery of an organic vanadium salt, which may act as an insulin-mimetic on fracture healing. Using a BB Wistar rat femoral fracture model, local vanadyl acetylacetonate (VAC) was delivered to the fracture site and histomorphometry, mechanical testing, and immunohistochemistry were performed. Callus percent cartilage was 200% higher at day 7 (p < 0.05) and 88% higher at day 10 (p < 0.05) in the animals treated with 1.5 mg/kg of VAC. Callus percent mineralized tissue was 37% higher at day 14 (p < 0.05) and 31% higher at day 21 (p < 0.05) in the animals treated with 1.5 mg/kg of VAC. Maximum torque to failure was 104% and 154% higher at 4 weeks post-fracture (p < 0.05) for the healing femurs from the VAC-treated (1.5 and 3.0 mg/kg) animals. Animals treated with other VAC doses demonstrated increased mechanical parameters at 4 weeks (p < 0.05). Immunohistochemistry detected 62% more proliferating cells at days 7 (p < 0.05) and 94% more at day 10 (p < 0.05) in the animals treated with 1.5 mg/kg VAC. Results showed 100% more vascular endothelial growth factor-C (VEGF-C) positive cells and 80% more blood vessels at day 7 (p < 0.05) within the callus subperiosteal region of VAC-treated animals (1.5 mg/kg) compared to controls. The results suggest that local VAC treatment affects chondrogenesis and angiogenesis within the first 7-10 days post-fracture, which leads to enhanced mineralized tissue formation and accelerated fracture repair as early as 3-4 weeks post-fracture.
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December 2012