Platelet-derived Growth Factor BB Homodimer Research Articles

A retrospective review of recombinant human platelet-derived growth factor with beta-tricalcium phosphate bone graft substitute use in hindfoot and/or ankle arthrodesis

BackgroundNonunion following foot and ankle arthrodesis can cause chronic pain and disability, poor patient satisfaction, and increased healthcare costs. Nonunion rates are reported in 10%–12% of primary foot and/or ankle arthrodesis procedures, with significantly greater rates among patients with high-risk factors such as smoking, diabetes, obesity, or Charcot neuroarthropathy. Recombinant human platelet-derived growth factor BB-homodimer with beta-tricalcium phosphate (rhPDGF-BB/β-TCP) is a bone graft substitute that has demonstrated efficacy in foot and ankle fusion rates that are comparable to autograft. MethodsCharts and radiographs were retrospectively reviewed on consecutive adult patients undergoing talonavicular, calcaneal-cuboid, subtalar, and/or ankle arthrodesis utilizing rhPDGF-BB/β-TCP bone graft substitute. The primary outcome measures were rate of and mean time to fusion, mean time to return to function, and incidence of adverse events. ResultsThis study reviewed133 patients who underwent 209 hindfoot and/or ankle joint arthrodesis procedures with a mean follow-up 20.34 ± 11.05 months. The overall fusion rate was 92.82% (194/209 joints) with a mean time to fusion of 13.14 ± 2.52 weeks and return to function of 16.56 ± 3.26 weeks. Overall, there were 7 (5.26%) patients who experienced an adverse event (AE) with 15 (7.18%) joints experiencing a nonunion. ConclusionFusion rates with rhPDGF-BB/β-TCP bone grafting material compared favorably to autograft controls when used in hindfoot and/or ankle arthrodesis. No AEwas related to rhPDGF-BB/β-TCP. This study suggests that using rhPDGF-BB/β-TCP is effective in hindfoot and/or ankle arthrodesis, even among patients with comorbidities who are at a higher risk of developing a nonunion. Level of clinical evidence3.

Human platelet lysates stimulate in vitro proliferation of human endometrial cells from patients with a history of recurrent implantation failure

To optimize and compare the isolation of platelet-rich plasma (PRP) and its cryopreserved derivative, platelet lysate (PL), to a commercial human platelet lysate (HPL) product PLUS and investigate their proliferative stimulation on primary human endometrial cells invitro. Basic research. Academic fertility center. Three healthy blood donors and eight patients with a history of recurrent implantation failure. Stimulated proliferation of isolated primary endometrial epithelial cells and endometrial stromal cells invitro with autologous and nonautologous HPL (PLUS; Compass Biomedical). Platelet-derived growth factor BB homodimer protein content in isolated PRP/PL and commercial HPL and endometrial epithelial cell and endometrial stromal cell proliferation after 24- or 48-hour stimulation with PL (measured by metabolic activity and Ki67 expression). To optimize and compare the isolation of autologous PRP/PL, three double-centrifugation protocols were assessed by flow cytometry for platelet yield (CD45-CD41+CD61+) and platelet-derived growth factor BB homodimer protein content by enzyme-linked immunosorbent assay. Cryopreserved PL, especially isolated by our fastest protocol, contained higher protein concentrations and, thus, was optimal for experimental flexibility compared with fresh PRP. The autologous and commercial PLs displayed comparable immune and growth factor content and stimulation of cell proliferation invitro. Our results provide the groundwork for the isolation and use of HPL to stimulate endometrial growth. Furthermore, commercial PL consistently stimulated cell proliferation and may allow standardization of clinical treatment for recurrent implantation failure.

Serum platelet-derived growth factor-BB levels as a potential biomarker in assessing the metabolic activity of lesions in alveolar echinococcosis patients

BackgroundAlveolar echinococcosis (AE) is a chronic disease caused by the larval stage of Echinococcus multilocularis. Assessing the metabolic activity of AE lesions is critical to evaluate disease progression and survey treatment options. There is an urgent need to identify more rapid, convenient, and non-invasive clinical detection methods to substitute the current techniques. Herein, we evaluated the viability of platelet-derived growth factor-BB (PDGF-BB) as a biomarker for detecting the metabolic activity of AE patients and their correlations with clinicopathological features of AE patients. MethodsSera were collected from 28 AE patients and a homogenous cohort of 28 healthy individuals. The concentration of serum PDGF-BB homodimers (sPDGF-BB) was assessed via an enzyme-linked immunosorbent assay (ELISA). Liver tissue samples were obtained from a consecutive series of 28 AE patients who underwent surgical resection. Thereafter, we determined the expression levels of local PDGF-BB and platelet-derived growth factor receptor-β (PDGFR-β) through immunohistochemistry (IHC). Correlations of PDGF-BB expression levels with clinicopathological features of AE patients were analyzed using SPSS. ResultsThe concentrations of sPDGF-BB were significantly lower in AE patients (p < 0.0001), particularly in High Metabolically Active AE patients (HMAE) patients (p < 0.05). The expression levels of PDGF-BB and its receptor were both significantly higher in close liver tissue (CLT) in AE patients (p < 0.0001). We also found that metabolically active AE and sPDGF-BB are significantly negatively correlated (r = -0.624, p = 0.0004). Beside, the local expression levels of PDGF-BB was positively correlated with metabolic activity, PNM stage, and lesion size. Notably, the sPDGF-BB levels were proposed as a potential biomarker for assessing metabolic activity of AE, with 81.0% sensitivity and 85.7% specificity (95% confidence interval, p = 0.003). ConclusionsSerum levels of PDGF-BB could be a simple, non-invasive, and quick biomarker for assessing the metabolic activity of lesions in AE patients.

A Multicenter, Retrospective, Case Series of Patients With Charcot Neuroarthropathy Deformities Undergoing Arthrodesis Utilizing Recombinant Human Platelet-derived Growth Factor With Beta-Tricalcium Phosphate

Charcot neuroarthropathy has traditionally been treated using both nonsurgical and surgical strategies. Recently, orthobiologics have been used to promote arthrodesis in Charcot reconstructions, obviating the need for bone graft in some cases. Recombinant human platelet-derived growth factor BB homodimer (rhPDGF-BB) in combination with beta-tricalcium phosphate scaffold (β-TCP) is a bone graft substitute shown to have comparable efficacy to autograft in incidence of foot and ankle fusion. This multicenter, consecutive case series analyzed patients undergoing Charcot reconstructions utilizing rhPDGF-BB/β-TCP for joint fusion. In this cohort, 98 patients (62.24% male) with a mean age of 62.82 ± 10.28 years (range 40-87) had a fusion incidence of 217 of 223 joints (97.31%) with a mean time to fusion of 13.09 ± 4.87 weeks (range 6-30). There were 6 nonunions in the patient population. Fusion was defined as ≥50% osseous bridging based on computed tomography and/or radiographic consolidation, in addition to clinical findings. With an overall complication rate of 26.53% (26/98), adverse events occurring in more than 1 patient limb included hardware failures (n = 7, 7.14%), infection (n = 4, 4.08%), wound dehiscence (n = 4, 4.08%), amputation (n = 3, 3.06%), and death (n = 2, 2.04%). There were no adverse events related to the grafting material. From this review, we found rhPDGF-BB/β-TCP to be a safe and effective graft material that can be considered a viable alternative to autograft, even in high-risk patients such as those with Charcot neuroarthropathy.

The Impact of Patient Age on Foot and Ankle Arthrodesis Supplemented with Autograft or an Autograft Alternative (rhPDGF-BB/β-TCP).

Background:A recent survey of orthopaedic surgeons asking about risk factors for nonunion following foot and ankle arthrodesis revealed that patient age is considered to be a relatively low risk factor, despite the potential for autologous graft quality to deteriorate with increasing age. The purpose of the current study was to evaluate the impact of patient age and graft type on fusion rates following hindfoot and ankle arthrodesis.Methods:In this study, we analyzed data from a previously published clinical trial, comparing fusion success in 397 subjects who underwent hindfoot or ankle arthrodesis (597 joints) supplemented with either autograft or an osteoinductive autograft alternative, recombinant human platelet-derived growth factor-BB homodimer carried in beta-tricalcium phosphate (rhPDGF-BB/β-TCP). The odds of fusion success were compared among subjects older or younger than age thresholds of 55, 60, 65, 70, and 75 years. The odds of fusion success were also compared between autograft and rhPDGF-BB/β-TCP among subjects older than each age threshold.Results:In the autograft group, the joints of subjects who were younger than the age thresholds of 60 and 65 years had >2 times the odds of successful fusion compared with those of older subjects. There was no significant difference in the odds of fusion success between the older and younger subjects at the age threshold of 55 years. In the rhPDGF-BB/β-TCP group, there was no significant difference in the odds of successful fusion between older and younger subjects at any age threshold. When the odds of fusion success were compared between the 2 graft materials in subjects who were older than each age threshold, rhPDGF-BB/β-TCP had approximately 2 times the odds of fusion success compared with autograft for all thresholds, except 55 years.Conclusions:The presented evidence suggests that age is an identifiable and concerning risk factor for hindfoot and ankle arthrodesis nonunion, a finding in contrast to the wider perception in the surgeon community. Notably, patients ≥60 years of age had significantly lower odds of fusion success with the use of autograft. The data reveal that use of rhPDGF-BB/β-TCP as an alternative bone-healing adjunct may help mitigate the risk of nonunion when these procedures are performed in the elderly population.Level of Evidence:Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Extraction Socket Preservation Using Growth Factors and Stem Cells: a Systematic Review

ABSTRACTObjectivesTo evaluate the reported literature on the use of stem cells or growth factors for post extraction treatment of the alveolar bone.Material and MethodsA NCBI PubMed and PubMed Central databases search was conducted between September 2010 and August 2018, to identify animal or clinical studies reporting the clinical, radiographical and/or histological outcomes of socket preservation techniques after applying mesenchymal stem cells or growth factors. Only studies published in English language in the last 10 years were included in the study.ResultsEleven studies were identified fulfilling the inclusion criteria. They evaluate a total of 386 post extraction sockets. The main tested materials identified in the current review were bone morphogenetic protein-2 - 3 studies and mesenchymal stem cells - 3 studies. Other comparators were bone morphogenetic protein-9, platelet-derived growth factor-BB homodimers and bone marrow. Overall evaluation indicate positive results for all test groups showing differences in final socket width between 0.64 and 1.28 mm favouring the test groups. Histologically, no particular differences are detected between test and control groups. Most of the studies present low risk of bias.ConclusionsIn general, the use of mesenchymal stem cells or bioactive osteogenic molecules favours bone regeneration after tooth extraction, as evaluated clinically, radiographically and histologically. However, specific differences that support particular recommendations are still unclear in light of the current published evidence. Future studies should include the standardization of the mesenchymal stem cells selection and purification as well as dosage and delivery methods of bioactive molecules.

Recombinant Human Platelet-Derived Growth Factor BB in Combination With a Beta-Tricalcium Phosphate (rhPDGF-BB/β-TCP)-Collagen Matrix as an Alternative to Autograft.

Joint arthrodesis often employs autograft to promote union; graft harvesting can lead to perioperative morbidity. A Canadian randomized controlled trial (RCT) demonstrated that recombinant human platelet-derived growth factor BB homodimer (rhPDGF-BB) combined with beta-tricalcium phosphate (β-TCP)-collagen was a safe, effective alternative to autograft. This multicenter North American RCT compared the safety and efficacy of rhPDGF-BB/β-TCP-collagen with autograft for ankle and hindfoot fusion. Subclassification using propensity scores (PS) incorporated patients from previous trials for enhanced statistical power for noninferiority testing and broader review of treatments. Patients requiring ankle or hindfoot arthrodesis and supplemental bone graft were treated with rhPDGF-BB/β-TCP-collagen (n = 69) or autograft (n = 35). Outcomes included joint fusion on computed tomography (24 weeks), clinical healing status, visual analog scale (VAS) pain, Short-Form 12 (SF-12), American Orthopaedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot Scale, and Foot Function Index (FFI) scores over 52 weeks. PS methodology addressed potential selection bias arising from pooling data among these patients and 2 previous RCTs with similar inclusion criteria, surgical techniques, graft harvest techniques, and outcomes. All 132 rhPDGF-BB/β-TCP-collagen-treated patients and 167 of 189 candidate autograft-treated controls were selected for comparison by an independent statistician blinded to outcomes. In the PS subclassification, 68.1% treatment patients and 68.4% controls achieved >50% osseous bridging at fusion sites. Clinical healing status was achieved in 84.8% of treated patients and 90.7% of controls at 52 weeks. Clinical, functional, and quality of life results demonstrated noninferiority of rhPDGF-BB/β-TCP-collagen to autograft. Safety-related outcomes were equivalent. PS subclassification analysis of 3 RCTs demonstrated that rhPDGF-BB/β-TCP-collagen was as effective as autograft for ankle and hindfoot fusions, with less pain and morbidity than treatment with autograft. Level I, prospective randomized study.

Salvianolic Acid A Attenuates Endoplasmic Reticulum Stress and Protects Against Cholestasis-Induced Liver Fibrosis via the SIRT1/HSF1 Pathway.

Background: Endoplasmic reticulum stress (ER stress) plays a critical role in the pathogenesis of liver fibrosis; thus, it can be a potential therapeutic target of fibrosis. However, the mechanism of ER stress regulation in fibrosis, particularly through sirtuin 1 (SIRT1), remains unclear. The objective of this study was to investigate the effect of SIRT1-mediated inhibition of ER stress in bile duct ligation (BDL)-induced liver fibrosis, and to explore the effect of salvianolic acid A (SalA) on BDL-induced liver fibrosis through SIRT1/heat shock factor 1 (HSF1) signaling.Materials and Methods: We explored the effects of SalA on liver fibrosis and ER stress in BDL-induced liver fibrosis in rats and the human hepatic stellate cell line LX2 cells. The LX2 cells were treated with 20 ng of platelet-derived growth factor-BB homodimer (PDGF-BB) for 24 h, and then incubated in the absence or presence of SalA (25 μM) for 24 h.Results: In vivo, SalA treatment alleviated BDL-induced liver injury and ER stress. Importantly, SalA treatment increased HSF1 expression and activity using a SIRT1-dependent mechanism. In LX2 cells, PDGF-BB induced ER stress and fibrosis were blocked by HSF1 overexpression. Furthermore, SIRT1 siRNA abrogated the SalA-mediated promotion of HSF1 deacetylation and expression, suggesting that SalA-mediated protection occurs by SIRT1 targeting HSF1 for deacetylation.Conclusion: This is the first study to identify the SIRT1/HSF1 pathway as a key therapeutic target for controlling BDL-induced liver fibrosis and to show that SalA confers protection against BDL- and PDGF-BB-induced hepatic fibrosis and ER stress through SIRT1-mediated HSF1 deacetylation.

Prospective Randomized Controlled Trial of Hindfoot and Ankle Fusions Treated With rhPDGF-BB in Combination With a β-TCP-Collagen Matrix.

Ankle and hindfoot arthrodesis is often supplemented with autograft to promote bony union. Autograft harvest can lead to increased perioperative morbidity. Purified recombinant human platelet-derived growth factor BB homodimer (rhPDGF-BB) has stimulated bone formation in mandibular defects and hindfoot fusion. This randomized controlled trial evaluated the efficacy and safety of rhPDGF-BB combined with an injectable, osteoconductive beta-tricalcium phosphate (β-TCP)-collagen matrix versus autograft in ankle and hindfoot fusions. Seventy-five patients requiring ankle or hindfoot fusion were randomized 5:1 for rhPDGF-BB/β-TCP-collagen (treatment, n = 63) or autograft (control, n = 12). Prospective analysis included 142 autograft control subjects from another clinical trial with identical study protocols. Standardized operative and postoperative protocols were used. Patients underwent standard internal fixation augmented with autograft or 0.3 mg/mL rhPDGF-BB/β-TCP-collagen. Radiologic, clinical, and quality-of-life outcomes were assessed over 52 weeks. Primary outcome was joint fusion (50% or more osseous bridging on computed tomography) at 24 weeks. Secondary outcomes included radiographs, clinical healing status, visual analog scale pain score, American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Scale score, Foot Function Index score, and Short Form-12 score. Noninferiority P values were calculated. Complete fusion of all involved joints at 24 weeks as indicated by computed tomography was achieved in 53 of 63 (84%) rhPDGF-BB/β-TCP-collagen-treated patients and 100 of 154 (65%) autograft-treated patients (P < .001). Mean time to fusion was 14.3 ± 8.9 weeks for rhPDGF-BB/β-TCP-collagen patients versus 19.7 ± 11.5 weeks for autograft patients (P < .01). Clinical success at 52 weeks was achieved in 57 of 63 (91%) rhPDGF-BB/β-TCP-collagen patients and 120 of 154 (78%) autograft patients (P < .001). Safety-related outcomes were equivalent. Autograft controls had 2 bone graft harvest infections. Application of rhPDGF-BB/β-TCP-collagen was a safe, effective alternative to autograft for ankle and hindfoot fusions, eliminating the pain and morbidity associated with autograft harvesting. Level I, prospective randomized study.

Antifibrotic and Anti-inflammatory Activity of the Tyrosine Kinase Inhibitor Nintedanib in Experimental Models of Lung Fibrosis

The tyrosine kinase inhibitor nintedanib (BIBF 1120) is in clinical development for the treatment of idiopathic pulmonary fibrosis. To explore its mode of action, nintedanib was tested in human lung fibroblasts and mouse models of lung fibrosis. Human lung fibroblasts expressing platelet-derived growth factor (PDGF) receptor-α and -β were stimulated with platelet-derived growth factor BB (homodimer) (PDGF-BB). Receptor activation was assessed by autophosphorylation and cell proliferation by bromodeoxyuridine incorporation. Transforming growth factor β (TGFβ)-induced fibroblast to myofibroblast transformation was determined by α-smooth muscle actin (αSMA) mRNA analysis. Lung fibrosis was induced in mice by intratracheal bleomycin or silica particle administration. Nintedanib was administered every day by gavage at 30, 60, or 100 mg/kg. Preventive nintedanib treatment regimen started on the day that bleomycin was administered. Therapeutic treatment regimen started at various times after the induction of lung fibrosis. Bleomycin caused increased macrophages and lymphocytes in the bronchoalveolar lavage (BAL) and elevated interleukin-1β (IL-1β), tissue inhibitor of metalloproteinase-1 (TIMP-1), and collagen in lung tissue. Histology revealed chronic inflammation and fibrosis. Silica-induced lung pathology additionally showed elevated BAL neutrophils, keratinocyte chemoattractant (KC) levels, and granuloma formation. Nintedanib inhibited PDGF receptor activation, fibroblast proliferation, and fibroblast to myofibroblast transformation. Nintedanib significantly reduced BAL lymphocytes and neutrophils but not macrophages. Furthermore, interleukin-1β, KC, TIMP-1, and lung collagen were significantly reduced. Histologic analysis showed significantly diminished lung inflammation, granuloma formation, and fibrosis. The therapeutic effect was dependent on treatment start and duration. Nintedanib inhibited receptor tyrosine kinase activation and the proliferation and transformation of human lung fibroblasts and showed antifibrotic and anti-inflammatory activity in two animal models of pulmonary fibrosis. These results suggest that nintedanib may impact the progressive course of fibrotic lung diseases such as idiopathic pulmonary fibrosis.

Recombinant Human Platelet-Derived Growth Factor-BB and Beta-Tricalcium Phosphate (rhPDGF-BB/β-TCP): An Alternative to Autogenous Bone Graft

Joint arthrodesis employing autogenous bone graft (autograft) remains a mainstay in the treatment of many foot and ankle problems. However, graft harvest can lead to perioperative morbidity and increased cost. We tested the hypothesis that purified recombinant human platelet-derived growth factor-BB (rhPDGF-BB) homodimer combined with an osteoconductive matrix (beta-tricalcium phosphate [β-TCP]) would be a safe and effective alternative to autograft. A total of 434 patients were enrolled in thirty-seven clinical sites across North America in a prospective, randomized (2:1), controlled, non-inferiority clinical trial to compare the safety and efficacy of the combination rhPDGF-BB and β-TCP with those of autograft in patients requiring hindfoot or ankle arthrodesis. Radiographic, clinical, functional, and quality-of-life end points were assessed through fifty-two weeks postoperatively. Two hundred and sixty patients (394 joints) underwent arthrodesis with use of rhPDGF-BB/β-TCP. One hundred and thirty-seven patients (203 joints) underwent arthrodesis with use of autograft. With regard to the primary end point, 159 patients (61.2% [262 joints (66.5%)]) in the rhPDGF-BB/β-TCP group and eighty-five patients (62.0% [127 joints (62.6%)]) in the autograft group were fused as determined by computed tomography at six months (p < 0.05). Clinically, 224 patients (86.2%) [348 joints (88.3%)]) in the rhPDGF-BB/β-TCP group were considered healed at fifty-two weeks, compared with 120 patients (87.6% [177 joints (87.2%)] in the autograft group (p = 0.008). Overall, fourteen of sixteen secondary end points at twenty-four weeks and fifteen of sixteen secondary end points at fifty-two weeks demonstrated statistical non-inferiority between the groups, and patients in the rhPDGF-BB/β-TCP group were found to have less pain and an improved safety profile. In patients requiring hindfoot or ankle arthrodesis, treatment with rhPDGF-BB/β-TCP resulted in comparable fusion rates, less pain, and fewer side effects as compared with treatment with autograft.

Percutaneous injection of Augment Injectable Bone Graft (rhPDGF-BB and β-tricalcium phosphate [β-TCP]/bovine Type I collagen matrix) increases vertebral bone mineral density in geriatric female baboons

Background contextRecombinant human platelet-derived growth factor-BB (rhPDGF-BB) homodimer is a chemotactic, mitogenic, and angiogenic factor expressed by platelets. This biological triad is profoundly important in the bone regenerative cascade. Therefore, the expectation was that rhPDGF-BB locally administered to designated lumbar vertebrae in a soluble Type I bovine collagen/β-tricalcium phosphate (β-TCP) injectable paste would have an osteoanabolic effect. PurposeThe study objective focused on safety and efficacy of the rhPDGF-BB and soluble Type I bovine collagen/β-TCP to increase bone density when injected directly into specific lumbar vertebral bodies in elderly (17- to 18-year-old) female baboons. Study design/settingThe study was designed to determine whether vertebral bone mineral density (BMD) in aged female baboons could be increased by locally administering recombinant rhPDGF-BB combined in a soluble Type I bovine collagen/β-TCP paste formulation. MethodsA total of six baboons were divided equally into two groups. Group 1 received 1.0 mg/mL rhPDGF-BB in 20 mM sodium acetate plus soluble Type I bovine collagen/β-TCP. Group 2 was treated with 20 mM sodium acetate plus soluble Type I bovine collagen/β-TCP. Baboons in each group also received a sham surgery. Surgery was conducted using a percutaneous, fluoroscopically guided approach, and quantitative computed tomography (qCT) and radiographs were done at dedicated time periods. The qCT was used to determine volumetric BMD (vBMD). At euthanasia (36-week posttreatment), lumbar vertebrae were recovered and analyzed by qCT scans and histology. Funds were received to support this work from BioMimetic Therapeutics, Inc. The device that is the subject of this manuscript is not Food Drug Administration approved for this indication and is not commercially available in the United States. ResultsThe qCT and histopathological data suggested that vBMD and bone morphology increased significantly in the lumbar vertebrae treated with the rhPDGF-BB–containing composition. ConclusionsBone mineral density and bone morphology quality of lumbar vertebrae in aged female baboons were improved by direct injection of rhPDGF-BB in a soluble Type I bovine collagen/β-TCP paste. Throughout the course of the study, there were neither local nor systemic adverse effects.

Effect of Implantation of Augment® Bone Graft on Serum Concentrations of Platelet-Derived Growth Factors: A Pharmacokinetic Study

Augment(®) Bone Graft is a bone graft substitute intended to be used as an alternative to autologous bone graft in the fusion of hindfoot and ankle joints. Augment(®) Bone Graft is a combination device comprised of beta-tricalcium phosphate (β-TCP) and recombinant human platelet-derived growth factor BB homodimer (rhPDGF-BB). This human pharmacokinetic study was undertaken to assess the effect of Augment(®) Bone Graft implantation on the serum concentration of platelet-derived growth factors (PDGFs). Under the terms of a Research Ethics Board-approved protocol, Augment(®) Bone Graft was implanted in patients (n = 7) undergoing hindfoot and ankle arthrodesis procedures requiring graft material. The control cohort of the study (n = 4) received autologous bone graft. The serum concentrations of PDGF isoforms AA, AB and BB in blood samples, obtained prior to and at ten time points (up to 7 days) after surgery, were measured using enzyme-linked immunosorbent assays (ELISA). The serum concentration of PDGF-BB did not vary significantly from baseline (median of the combined cohorts 3.89 ng/mL) throughout the course of the study. The serum concentrations of PDGF-AA, PDGF-AB and total PDGF did not deviate from their baseline values (medians of the combined cohorts were 2.87, 14.95 and 20.19 ng/mL for PDGF-AA, PDGF-AB and total PDGF, respectively) except for the last time point in which they were increased (medians for the combined cohorts were 4.71, 20.42 and 30.29 ng/mL for PDGF-AA, PDGF-AB and total PDGF, respectively). There were no differences between the two treatment groups with regard to changes in the serum concentrations of PDGF. None of the samples tested contained anti-PDGF-BB antibodies. Analysis of the data demonstrated that the serum concentrations of all three PDGF isoforms analysed were unaffected by implantation of Augment(®) Bone Graft.

Regenerative Tendon and Ligament Healing: Opportunities with Recombinant Human Platelet-Derived Growth Factor BB-Homodimer

Intrinsic tendon healing in response to injury is a reparative process that often results in formation of scar tissue with functional and mechanical properties inferior to those of the native tendon. Development of therapies that can promote regenerative, rather than reparative, healing hold the promise of improving patient recovery from tendon and ligament injuries by producing tissue that is morphologically and functionally equivalent to the native tissue. One therapeutic approach that has been a frequent topic of investigation in the preclinical literature is the use of recombinant human platelet-derived growth factor-BB (rhPDGF-BB) to augment tendon and ligament repair. The chemotactic, mitogenic, and pro-angiogenic properties of rhPDGF-BB have been shown to result in recruitment and proliferation of tenogenic cells and a commensurate boost in extracellular matrix deposition and organization, improving the morphological and biomechanical properties of healing tendons and ligaments. The outcomes of the preclinical studies reviewed here strongly suggest that rhPDGF-BB will provide a new therapeutic opportunity to improve the treatment of injured tendons and ligaments.

Targeted Biodegradable Nanoparticles for Drug Delivery to Smooth Muscle Cells

Targeted delivery of therapeutic agents to prevent smooth muscle cell (SMC) proliferation is important in averting restenosis (a narrowing of blood vessels). Since platelet derived growth factor (PDGF) receptors are over-expressed in proliferating SMCs after injury from cardiovascular interventions, such as angioplasty and stent implantation, our hypothesis is that conjugation of PDGF-BB (platelet-derived growth factor BB (homodimer)) peptides to biodegradable poly (D,L-lactic-co-glycolide) (PLGA) nanoparticles (NPs) would exhibit an increased uptake of these NPs by proliferating SMCs. In this study, poly (D,L-lactide-co-glycolide) (PLGA) nanoparticles containing dexamethasone were formulated and conjugated with PDGF-BB peptides. These NPs were stable, biocompatible, and exhibited a sustained drug release over 14 days. Various particle uptake studies using HASMCs (human aortic smooth muscle cells) demonstrated that PDGF-BB peptide-conjugated nanoparticles significantly increased cellular uptake and decreased proliferation of HASMCs compared to control nanoparticles (without conjugation of PDGF-BB peptides). These NPs were internalized primarily by clathrin-mediated endocytosis and macropinocytosis. Our in vitro results suggest that PDGF-BB peptide-conjugated NPs could represent as an effective targeted, sustained therapeutic delivery system to reduce restenosis and neointimal hyperplasia.

Antiproliferative effect of salvianolic acid A on rat hepatic stellate cells

Suppression of activation or proliferation, or induction of apoptosis in hepatic stellate cells (HSCs) have been proposed as therapeutic strategies against liver fibrosis. Salvia miltiorrhiza has been reported to exert antifibrotic effects in rats with hepatic fibrosis, but its mechanisms of action remain to be clarified. We have investigated the effects of salvianolic acid A (Sal A), an active principle from S. miltiorrhiza, on the proliferation-related biomarkers in a cell line of rat HSCs (HSC-T6) stimulated with platelet-derived growth factor-BB homodimer (PDGF-BB). DNA synthesis (bromodeoxyuridine (BrdU) incorporation), cell cycle related proteins and apoptosis markers were determined to evaluate the inhibitory effects of Sal A. The results showed that Sal A (1-10 microM) concentration-dependently attenuated PDGF-BB-stimulated proliferation (BrdU incorporation) in HSC-T6 cells. Sal A at 10 microM induced cell apoptosis in PDGF-BB-incubated HSCs, together with a reduction of Bcl-2 protein expression, induction of cell cycle inhibitory proteins p21 and p27, and down-regulation of cyclins D1 and E, suppression of Akt phosphorylation, reduction in PDGF receptor phosphorylation, and an increase in caspase-3 activity. Sal A exerted no direct cytotoxicity on primary hepatocytes and HSC-T6 cells under experimental concentrations. Our results suggested that Sal A inhibited PDGF-BB-activated HSC proliferation, partially through apoptosis induction.

Serum levels of platelet-derived growth factor BB homodimers are increased in male children with autism

The neurobiological basis of autism remains poorly understood. To examine the role played by serum cytokines in brain development, we hypothesized that Platelet-Derived Growth Factor (PDGF) and Vascular Endothelial Growth Factor (VEGF) may be associated with pathophysiology of autism. In this study, we screened serum levels of these growth factors in young male subjects with autism. We measured serum levels of PDGF subtypes and VEGF in the 31 male children with autism (6-19 years old) and 31 healthy age- and gender-matched subjects. The serum levels of PDGF-BB in male children with autism (N=31, 5624.5+/-1651.8 pg/mL [mean+/-SD]) were significantly higher (two-tailed Student's t-test: p=0.0188) than those of normal control subjects (N=31, 4758.2+/-1521.5 pg/mL [mean+/-SD]). There was a significant and positive correlation (Pearson's r=0.5320, p=0.0010) between the serum levels of PDGF-BB and the Autism Diagnostic Interview-Revised (ADI-R) domain C scores, which represent stereotyped patterns of behavior in the children with autism. However, there were no marked or significant correlations between serum PDGF-BB levels and clinical variables, including the other ADI-R scores and Intellectual Quotient (IQ) scores by WAIS-R. There were no significant change and correlations with clinical variables in serum PDGF-AA, PDGF-AB, and VEGF levels in the children with autism. Increased levels of serum PDGF-BB homodimers might be implicated in the pathophysiology of autism.

An Endogenous Inhibitor of Focal Adhesion Kinase Blocks Rac1/JNK but Not Ras/ERK-dependent Signaling in Vascular Smooth Muscle Cells

Humoral factors and extracellular matrix are critical co-regulators of smooth muscle cell (SMC) migration and proliferation. We reported previously that focal adhesion kinase (FAK)-related non-kinase (FRNK) is expressed selectively in SMC and can inhibit platelet-derived growth factor BB homodimer (PDGF-BB)-induced proliferation and migration of SMC by attenuating FAK activity. The goal of the current studies was to identify the mechanism by which FAK/FRNK regulates SMC growth and migration in response to diverse mitogenic signals. Transient overexpression of FRNK in SMC attenuated autophosphorylation of FAK at Tyr-397, reduced Src family-dependent tyrosine phosphorylation of FAK at Tyr-576, Tyr-577, and Tyr-881, and reduced phosphorylation of the FAK/Src substrates Cas and paxillin. However, FRNK expression did not alter the magnitude or dynamics of ERK activation induced by PDGF-BB or angiotensin II. Instead, FRNK expression markedly attenuated PDGF-BB-, angiotensin II-, and integrin-stimulated Rac1 activity and attenuates downstream signaling to JNK. Importantly, constitutively active Rac1 rescued the proliferation defects in FRNK expressing cells. Based on these observations, we hypothesize that FAK activation is required to integrate integrin signals with those from receptor tyrosine kinases and G protein-coupled receptors through downstream activation of Rac1 and that in SMC, FRNK may control proliferation and migration by buffering FAK-dependent Rac1 activation.

Platelet-derived growth factor BB secreted from osteoclasts acts as an osteoblastogenesis inhibitory factor.

Osteoclasts and osteoblasts are responsible for strict bone maintenance with a balance between bone formation and resorption by interacting with each other. Recently, it has been revealed that osteoblasts/stromal cells regulate differentiation of osteoclasts/hematopoietic cells by two factors, the receptor activator of nuclear factor-kappaB (NF-kappaB) ligand (RANKL) on the plasma membrane, and secreted osteoprotegerin (OPG). However, no factors have yet been reported by which osteoclasts/hematopoietic cells regulate osteoblasts/stromal cells. To elucidate the possibility of signal transduction from osteoclasts to osteoblasts, we studied the conditioned medium of mouse osteoclast-like myeloma cell line RAW264.7 treated with RANKL. We found that this medium contains a factor that inhibits differentiation of mouse osteoblast precursor-like cell line MC3T3-E1 to osteoblasts induced by bone morphogenetic protein 4 (BMP-4) and named this factor osteoblastogenesis inhibitory factor (OBIF). OBIF was purified by successive three-step chromatography by heparin affinity, anion exchange, and reversed-phase columns. Osteoblastogenesis inhibitory activity made one peak in each chromatography step, showing the factor is a single entity. Active fractions were loaded on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and bands of proteins were excised, digested by trypsin, and analyzed by liquid chromatography equipped with tandem mass spectrometry (LC/MS/MS). Consequently, we have identified this factor to be platelet-derived growth factor BB (PDGF BB) homodimer. Furthermore, this identification of PDGF BB as OBIF was confirmed by neutralization of the inhibitory activity of the medium with anti-PDGF antibody. These results show, for the first time, that osteoclasts regulate osteoblasts directly and suggest that PDGF BB is a key factor in bone remodeling.

Inhibitory mechanism of tranilast in human coronary artery smooth muscle cells proliferation, due to blockade of PDGF-BB-receptors.

We have previously reported that tranilast, an anti-allergic drug, prevented the experimental intimal thickening in the rat and mouse femoral arteries and its effect may be exerted through the inhibition of vascular smooth muscle cell proliferation. However, its inhibitory mechanism has yet to be understood. In this study, we investigated the inhibitory effect of tranilast on platelet-derived growth factor BB-homodimer (PDGF-BB) mediated signal transduction pathways in cultured human coronary artery smooth muscle cells (CASMCs). Growth responses to PDGF-BB were measured by [(3)H]-thymidine incorporation or cell counting. Activation of DNA synthesis and augmentation of cell proliferation stimulated by PDGF-BB in quiescent cultures of CASMCs were inhibited by tranilast in a concentration-dependent manner. Western blot analysis of lysates from CASMCs with an anti-activated mitogen-activated protein (MAP) kinase antibody revealed that tranilast (10 - 300 microM) inhibited MAP kinase activation by PDGF-BB in a concentration-dependent manner. Tranilast also reduced PDGF-BB-stimulated tyrosine phosphorylation of a 180 kDa band, corresponding in mass to the PDGF beta-receptor, as shown by immunoblots using an anti-phosphotyrosine antibody. Receptor-binding study with [(125)I]-PDGF-BB on CASMCs showed that tranilast (10 - 1000 microM) inhibited the specific binding of PDGF-BB to cell surface receptors in a concentration-dependent manner. Scatchard analysis revealed that pretreatment with 300 microM tranilast decreased the maximum binding capacity (B(max)) from 27.6 to 18.0 fmol 10(6) cells(-1) without affecting binding affinity (K(d) approximately 0.15 nM), indicating a non-competitive inhibition of the receptor binding. These results suggest that the suppression of human CASMC growth by tranilast might be at least partly due to blockade of PDGF-BB-receptor binding.