Platelet-derived Growth Factor AA Levels Research Articles

Analysis and comparison of autologous platelet-rich plasma preparation systems used in the treatment of enthesopathies: A preliminary study.

Autologous platelet-rich plasma (PRP) injection is an alternative but widely accepted method for the treatment of degenerative changes in tendon attachments known as enthesopathies. The PRP is considered a safe source for high concentrations of the growth factors involved in the healing process. Despite initial promising outcomes, many recent studies report conflicting results for this treatment. This may be due to differences in the concentrations of platelets and growth factors in PRPs obtained using different methods. The aim of this study was to compare PRP preparation systems in terms of morphotic components and selected growth factors to find the most appropriate procedure for the treatment of enthesopathies. Whole blood samples from 6 healthy male volunteers were collected. Using different commercial kits (Mini GPS III System, Arthrex ACP, and Xerthra, Dr. PRP), 4 PRPs were prepared from the blood of each participant. All samples were analyzed for the content of morphotic components and the following growth factors: transforming growth factor-β1 (TGF-β1), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and platelet-derived growth factor AA (PDGF-AA). The Mini GPS III produced PRP with the highest concentration of platelets and white blood cells (WBC) compared to the other systems included in the study. Significant differences in the levels of EGF and PDGF-AA were found only between the Mini GPS III and Arthrex ACP. There was positive correlation between the content of platelets and the levels of PDGF-AA and EGF. The red blood cells (RBC) concentration positively correlated with PDGF-AA, EGF and VEGF. This study showed differences between the morphotic components and levels of selected growth factors in PRP obtained with the different preparation methods. Due to insufficient data, we cannot argue for or against any of the studied protocols for the treatment of enthesopathy. Further studies on a larger population are required to validate our results.

Platelet Derived Growth Factor-AA Correlates With Muscle Function Tests and Quantitative Muscle Magnetic Resonance in Dystrophinopathies

Introduction: Duchenne (DMD) and Becker (BMD) muscular dystrophy are X-linked muscular disorders produced by mutations in the DMD gene which encodes the protein dystrophin. Both diseases are characterized by progressive involvement of skeletal, cardiac, and respiratory muscles. As new treatment strategies become available, reliable biomarkers and outcome measures that can monitor disease progression are needed for clinical trials.Methods: We collected clinical and functional data and blood samples from 19 DMD patients, 13 BMD patients, and 66 healthy controls (8 pediatric and 58 adult controls), and blood samples from 15 patients with dysferlinopathy (DYSF) and studied the serum concentration of 4 growth factors involved in the process of muscle fibrosis. We correlated the serum concentration of these growth factors with several muscle function tests, spirometry results and fat fraction identified by quantitative Dixon muscle MRI.Results: We found significant differences in the serum concentration of Platelet Derived Growth Factor-AA (PDGF-AA) between DMD patients and pediatric controls, in Connective Tissue Growth Factor (CTGF) between BMD patients and adult controls, and in and Transforming Growth Factor- β1 (TGF-β1) between BMD and DYSF patients. PDGF-AA showed a good correlation with several muscle function tests for both DMD and BMD patients and with thigh fat fraction in BMD patients. Moreover, PDGF-AA levels were increased in muscle biopsies of patients with DMD and BMD as was demonstrated by immunohistochemistry and Real-Time PCR studies.Conclusion: Our study suggests that PDGF-AA should be further investigated in a larger cohort of DMD and BMD patients because it might be a good biomarker candidate to monitor the progression of these diseases.

Changes in Aqueous Cytokine Levels Following Intravitreal Aflibercept in Treatment-Naive Patients with Diabetic Macular Edema.

Purpose: To investigate the changes in aqueous humor cytokine levels in response to short-term aflibercept therapy in treatment-naive patients with center-involving diabetic macular edema (DME). Methods: This is a prospective cohort study that included patients with treatment-naive DME with central subfield macular thickness ≥310 μm on optical coherence tomography from July 2015 to May 2017. Patients received 3 monthly intravitreal aflibercept injections. Aqueous samples for cytokine analysis were obtained before the first and third injections. Levels of various cytokines were measured using multiplex immunoassay. Main outcome measures were changes in aqueous cytokine levels from baseline to month 2. Results: A total of 17 patients were enrolled and 16 completed the study. The mean age was 57.2 ± 8.1 years. The following cytokines were significantly higher at month 2 versus baseline: transforming growth factor-beta (TGF-β)1 (P = 0.004), TGF-β2 (P = 0.017), inducible protein (IP)-10 (P = 0.011), and hepatocyte growth factor (HGF) (P = 0.02). There were significant reductions in the levels of vascular endothelial growth factor (VEGF) (P < 0.001), placental growth factor (PlGF) (P = 0.028), interleukin (IL)-6 (P = 0.011), and platelet-derived growth factor-AA (PDGF-AA) (P = 0.003). Conclusions: In treatment-naive patients with DME, short-term aflibercept therapy not only results in VEGF and PlGF suppression, but also leads to reduced levels of IL-6 and PDGF-AA and higher concentrations of TGF-β1, TGF-β2, HGF, and IP-10.

Multiple cytokine analyses of aqueous humor from the patients with retinitis pigmentosa

PurposeCataracts are the most common eye complications of retinitis pigmentosa (RP). This study aimed to investigate the cytokine profiles of the aqueous humor of RP with cataracts. MethodsThe aqueous humor was collected from RP eyes with cataract (RP group, n = 20) and age-related cataract eyes (ARC group, n = 20) during cataract surgery. The levels of 37 mediators were measured with multiplex fluorescent bead-based immunoassay and compared across groups. The correlation among chemokines, growth factors, and cytokines was analyzed with Spearman’s rank correlation coefficient. ResultsTwelve cytokines (IL-1α, IL-1β, IL-4, IL-10, TNF-α, IFN-γ, EGF, GM-CSF, PDGF-AB/BB, TGF-α, BMP-9, and E-selection) were below the limit of detection, and the detection rate of IL-6 was significantly higher in RP group than in the ARC group (P < 0.01). Compared with those in the control group, the aqueous humor levels of monocyte chemoattractant protein-1 (MCP-1), interleukin-(IL-)8, interferon gamma-induced protein (IP)-10, hepatocyte growth factor (HGF), platelet-derived growth factor AA (PDGF-AA), matrix metalloproteinase-2 (MMP-2), MMP3, MMP-7, MMP-8, plasminogen activator inhibitor-1 (PAI-1), and thrombospondin-2 (TSP-2) in the RP group increased significantly (P < 0.01). A lower level of BMP-4 in the aqueous humor was observed in the RP patients than in the controls (P < 0.05). ConclusionsSignificantly increased levels of PDGF-AA, MMP2, MMP3, MMP-7, MMP-8, PAI-1, and TSP-2 and lower levels of BMP-4 were found in the aqueous humor of RP patients. This result indicates a disturbance of the extracellular matrix (ECM) and cytokines in RP patients and suggests a possible role of these cytokines in the pathogenesis of capsular contraction syndrome (CCS) in RP patients.

EXPRESS: Angiogenic Profile Identifies Pulmonary Hypertension in Children with Down Syndrome.

Past studies have shown that lung angiogenic signaling may be abnormal in children with Down syndrome, but whether differences in circulating angiogenic proteins can identify pulmonary hypertension in children with Down syndrome is unknown. A prospective study of 78 children from birth to 21 years of age was conducted to evaluate clinical data, echocardiograms, and cardiac catheterizations. Four patient populations were enrolled, including children with Down syndrome who have pulmonary hypertension (Down syndrome + pulmonary hypertension, n = 12); control children without Down syndrome who have pulmonary hypertension (C + pulmonary hypertension, n = 15); children with Down syndrome without a known diagnosis of pulmonary hypertension (Down syndrome − pulmonary hypertension, n = 26); and children without Down syndrome or a known diagnosis of pulmonary hypertension (C − pulmonary hypertension, n = 25). Blood samples were collected at enrollment and concentrations for 11 proteins were evaluated. A classification tree was created to identify angiogenic peptide signals that may be associated with pulmonary hypertension in children with Down syndrome compared with controls. Findings identified elevated endostatin levels (>4.98 log10 pg/ml) were associated with Down syndrome. Platelet-derived growth factor AA levels (>2.51 log10 pg/ml) were higher in non-Down syndrome patients with pulmonary hypertension (C + pulmonary hypertension), whereas lower angiogenin (<5.428 log10 pg/ml) or lower angiogenin with elevated angiopoietin-1 levels (>3.59 log10 pg/ml) distinguished pulmonary hypertension in those with Down syndrome from the other groups. This study suggests that children with Down syndrome have high endostatin levels, but low levels of angiogenin levels in children with Down syndrome more often identified pulmonary hypertension than Down syndrome subjects without pulmonary hypertension or non-Down syndrome children. We speculate that these changes in circulating peptides support the concept of dysregulated angiogenesis in children with Down syndrome and pulmonary hypertension, which may further support potential utility as biomarkers for identifying subjects with Down syndrome at risk for pulmonary hypertension in this population.

The Influence of Naproxen on Biological Factors in Leukocyte-Rich Platelet-Rich Plasma: A Prospective Comparative Study

To quantify and compare normative catabolic and anabolic factor concentrations in leukocyte-rich platelet-rich plasma (LR-PRP) at various time points, including baseline, 1week after initiating naproxen use, and after a 1-week washout period. Asymptomatic healthy donors aged between 18 and 70years were recruited (average age, 36.6years; range, 25-64years). Subjects were excluded from the study if they were actively taking any prescribed medications or nonsteroidal anti-inflammatory drugs (NSAIDs) or if they had any of the following at present or previously: blood or immunosuppression disorders, cancer, osteonecrosis, rheumatoid arthritis, avascular necrosis, NSAID intolerance, gastrointestinal or peptic ulcer disease, or kidney dysfunction. The anabolic factors vascular endothelial growth factor, fibroblast growth factor 2, platelet-derived growth factor AB (PDGF-AB), and platelet-derived growth factor AA (PDGF-AA) and the catabolic factors interleukin (IL) 1β, IL-6, IL-8, and tumor necrosis factor α in LR-PRP were measured. Peripheral blood was drawn at 3 time points: baseline, after 1week of naproxen use, and after a 1-week washout period. The angiogenic factors PDGF-AA (44% decrease in median) and PDGF-AB (47% decrease) significantly declined from baseline (P < .05) after 1week of naproxen use. There was a significant recovery (P < .05) of PDGF-AA (94% increase) and PDGF-AB (153% increase) levels after the 1-week washout period, with a return to baseline levels. The catabolic factor IL-6 also had a significant decline from baseline (77% decrease in median, P < .05) after 1week of naproxen use. After a 1-week washout period, the IL-6 level was similar to the baseline level (130% increase, P < .05). Naproxen use diminished several biological factors in LR-PRP; however, a 1-week washout period was sufficient for the recovery of PDGF-AA, PDGF-AB, and IL-6 to return to baseline levels. Tumor necrosis factor α, IL-1β, IL-8, vascular endothelial growth factor, and fibroblast growth factor 2 did not show differences between the 3 time points of data collection. Discontinuing NSAIDs for a minimum of 1week before LR-PRP treatment may improve certain biological factor levels. Level II, prospective comparative study.

The association of maternal lymphatic markers and critical congenital heart defects in the fetus-A population based case-control study.

The objective ot this study was to investigate whether lymphatic markers measured in women during the second trimester are associated with critical congenital heart defects (CCHDs) in offspring. This is a retrospective cohort study of pregnant women who participated in the California Prenatal Screening Program. CCHD data in the offspring was captured by linking birth certificate data with hospital patient discharge records. Second trimester samples were assayed for vascular endothelial growth factor (VEGF), platelet derived growth factor (PDGF) AA/BB, and PDGF AB. Logistic models were used to evaluate the association between lymphatic biomarkers and CCHD. Models were adjusted for other serum biomarkers and maternal characteristics. Results are presented in odds ratios (OR) with 95% confidence intervals (CI). We identified 93 cases with CCHDs and 194 controls without CCHDs. The crude and adjusted OR for log (ln) VEGF was 1.07 (95%CI 0.94-1.22) and 1.08 (95%CI 0.94-1.24), respectively; for ln PDGF AB/BB was 0.93 (95%CI 0.6-1.35) and 0.58 (95%CI 0.32-1.05), respectively. There was a significant association between ln PDFG AA and CCHDs (crude OR 1.83 (95%CI 1.05-3.2); adjusted OR 2.41 (95%CI 1.06-5.44)). Levels of circulating PDGF AA were highest in cases with hypoplastic left heart syndrome (HLHS) (mean 8.78 +/- 1.54 pg/ml). In this study, increased mid-pregnancy maternal serum levels of PDGF AA were associated with CCHDs in offspring. The highest PDGF AA levels were found in mothers of fetuses with HLHS. These findings may be useful in screening for CCHDs and offer insight into their association with nuchal translucency.

Serum Markers of Neurodegeneration in Maple Syrup Urine Disease.

Maple syrup urine disease (MSUD) is an inherited disorder caused by deficient activity of the branched-chain α-keto acid dehydrogenase complex involved in the degradation pathway of branched-chain amino acids (BCAAs) and their respective α-keto-acids. Patients affected by MSUD present severe neurological symptoms and brain abnormalities, whose pathophysiology is poorly known. However, preclinical studies have suggested alterations in markers involved with neurodegeneration. Because there are no studies in the literature that report the neurodegenerative markers in MSUD patients, the present study evaluated neurodegenerative markers (brain-derived neurotrophic factor (BDNF), cathepsin D, neural cell adhesion molecule (NCAM), plasminogen activator inhibitor-1 total (PAI-1 (total)), platelet-derived growth factor AA (PDGF-AA), PDGF-AB/BB) in plasma from 10 MSUD patients during dietary treatment. Our results showed a significant decrease in BDNF and PDGF-AA levels in MSUD patients. On the other hand, NCAM and cathepsin D levels were significantly greater in MSUD patients compared to the control group, while no significant changes were observed in the levels of PAI-1 (total) and PDGF-AB/BB between the control and MSUD groups. Our data show that MSUD patients present alterations in proteins involved in the neurodegenerative process. Thus, the present findings corroborate previous studies that demonstrated that neurotrophic factors and lysosomal proteases may contribute, along with other mechanisms, to the intellectual deficit and neurodegeneration observed in MSUD.

Effect of Antioxidant Supplementation on Surrogate Markers of Fibrosis in Chronic Pancreatitis

This study aimed to determine the effect of antioxidant (AO) supplementation on surrogate markers of fibrosis in patients with chronic pancreatitis (CP). In a randomized, placebo (PL)-controlled trial, patients with CP were randomized to groups that were given PL or AO for 3 months. Outcome measures were change in serum levels of transforming growth factor β1 and platelet-derived growth factor AA (PDGF-AA) (primary outcome) as well as blood markers of oxidative stress (thiobarbituric acid-reactive substances) and AO status (ferric-reducing ability of plasma) (secondary outcome). Pain relief and analgesic requirement was also recorded. Patients (n = 61; mean [SD] age, 35.2 [10.0]; male patients, 43) were assigned to AO (n = 31) and PL (n = 30) groups. The median (range) percent reduction from baseline to 3 months in levels of PDGF-AA (17.1% [-25.3% to 88.7%] vs 2.8% [-243.1% to 30.2%]; P = 0.001), transforming growth factor β1 (P = 0.573), and thiobarbituric acid-reactive substances (P = 0.207) as well as percent increment from baseline to 3 months in ferric-reducing ability of plasma (P = 0.003) were higher in the AO group compared with the PL group. Proportion of patients who had both reduced PDGF-AA and reduced pain was greater in AO as compared with PL group (17/31 vs 9/30, P = 0.05) Reduction in markers of fibrosis (PDGF-AA) translated into clinical outcome (reduction in pain and analgesic requirements) in those supplemented with AOs in CP (trial registration, CTRI/2011/05/001747).

PDGF-AA and bFGF mediate B104CM-induced proliferation of oligodendrocyte precursor cells

The conditioned medium from B104 neuroblastoma cells (B104CM) induces proliferation of οligodendrocyte precursor cells (OPCs) in vitro, which indicates that certain factors contained within B104CM give instructional signals that direct the proliferation of OPCs. However, the OPC-proliferative factors present in B104CM have yet to be identified. Platelet-derived growth factor AA (PDGF-AA), basic fibroblast growth factor (bFGF) and insulin-like growth factor-1 (IGF-1) have been reported to act as potent mitogens for OPC proliferation. This raises the possibility that B104CM induces proliferation of OPCs through secretion of PDGF‑AA, bFGF and/or IGF-1. In the present study, we detected the expression and levels of PDGF-AA, bFGF and IGF-1 in B104 cells and B104CM, and observed the expression of their receptors in OPCs. The results indicated that these growth factors were expressed in B104 cells and B104CM. All 3 receptors, PDGFR, FGFR2 and IGF-1R, were also detected in OPCs. Furthermore, B104CM-stimulated OPC proliferation could be markedly decreased by both AG1295 (an inhibitor of PDGFR) and PD173074 (an inhibitor of FGFR). However, the inhibition of IGF-1R with AG1204 did not affect the proliferation of OPCs. Our study suggests that the PDGF-AA and bFGF in B104CM are 2 key factors that stimulate OPC proliferation.

Plasma Brain Derived Neurotropic Factor and Platelet Derived Growth Factor Levels Are Elevated in Children with Sickle Cell Anemia and Abnormal Transcranial Doppler and/or Stroke

Abstract 516Children with sickle cell anemia (SCA) are at increased risk for stroke due to abnormal cerebral blood flow (CBF). The Stroke Prevention (STOP I) study showed that abnormal CBF could be detected using Trans-cranial Doppler (TCD), and may predict the risk for stroke. High TCD may be an indicator of main or branch cerebral artery vascular dysfunction, stenosis or fibrosis. Abnormal CBF is associated with cerebral ischemia and ultimately stroke. Brain derived neurotropic factor (BDNF) is a nerve growth factor with anti-apoptotic and neuro-protective properties. It is released in the central nervous system in response to ischemia. Platelet derived growth factor (PDGF) is an endothelial and smooth muscle mitogen. We hypothesized that circulating BDNF and PDGF levels will be elevated and may be associated with abnormal CBF as indicated by high TCD velocity measurements.Three groups of children, i.e. 1) SCA with abnormal TCDs (SATCD) - abnormal TCD ≥200 cm/sec, 2) SCA with normal TCDs (SNTCD) -normal TCD ≤170 cm/sec and 3) healthy controls were investigated. Stored, baseline plasma samples from the Stroke Prevention (STOP I) study and from an ongoing study of nutritional effects on inflammation in SCA children (NUTSCD) were analyzed in duplicate, using a multiplex antibody immobilized bead assay. Plasma levels of BDNF, PDGF AA and AB/BB and 10 other pro- and anti-inflammatory cytokines were assessed. A total of 39 samples (11 SATCD, 21 SNTCD and 7 controls) were analyzed. Of the 11 SATCD, 8 were eventually randomized to the standard care (SC), while 3 were in the transfusion (Tx) arm of STOP I. Since some of the SCA patients subsequently developed stroke, the levels of BDNF and PDGF in those who did vs. did not develop stroke were compared. Except where not applicable, values are presented as mean±SD. Chi-square was used to access distribution, while means were compared using t-test and analysis of variance (ANOVA). A Receiver Operator Characteristic (ROC) curve was used to access the sensitivity of BDNF and PDGF in predicting abnormal CBF as indicated by abnormal TCD measurement.The TCD velocity for SATCD group was 250±32 cm/s. There was no statistically significant difference in age or gender distribution among the groups. The mean body mass index was significantly lower for SCA subjects compared with controls (15±1kg/m2 vs. 23±7 kg/m2, p= 0.026). There was a statistically significant difference in mean BDNF levels, which was highest in SATCD compared with SNTCD (234±53 vs. 166±110 pg/ml, p=0.036) and controls (34±20 pg/ml, p<0.001). Difference in the BDNF levels between SNTCD and controls was also statistically significant, p=0.006. PDGF AA levels were significantly higher in SATCD compared with SNTCD (356±147pg/ml vs. 227±156 pg/ml, p = 0.045) and controls (34±32pg/ml, p<0.001). Also, PDGF AA levels were significantly higher for SNTCD vs. controls (p = 0.014). Six of the 7 patients who developed stroke had abnormal TCD, while one had conditional TCD (186cm/s, F, 3yo). However, all SCA patients who subsequently developed stroke had significantly higher PDGF AA levels than those who did not (350±180pg/ml vs. 249±154pg/ml, p=0.039). The BDNF levels, were not significantly different for SCA who subsequently developed stroke vs. those who did not (201±69pg/ml vs. 186±106pg/ml). Of the 3 patients receiving Tx, one who eventually had stroke, had very high (pre-Tx) PDGF AA level (312pg/ml); almost as high as those on SC who developed stroke (358±197pg/ml, n=6), and higher than the remaining 2 Tx patients who did not develop stroke (233±0.5pg/ml). The ROC curve showed that both BDNF and PDGF were sensitive (AUC=0.8, p<0.05) predictors of abnormal CBF as indicated by high TCDs velocity measurement.High TCD velocity in children with SCA was associated with elevated BDNF and PDGF AA levels. Moreover, PDGF AA levels were significantly higher in the SCA patients who developed stroke. Further study is warranted to determine whether BDNF and/or PDFG AA, alone or with abnormal TCD, will better predict future stroke risk. [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Abstract 2041: PDGF inducible microRNAs regulate gene expression in cancer cells

Abstract Background: Platelet derived growth factor (PDGF)-regulated signaling plays a critical role in oncogenesis. By binding to the PDGF receptors, the Akt, Src and MAPK pathways are activated to regulate genes expression and cellular physiological processes. There are subtle functional differences between the effects of specific PDGF ligands (e.g. AA, BB), which are incompletely understood. MicroRNA(miR)s are single-stranded, 21-23 nucleotide regulatory RNAs that repress target gene expression either by inhibiting protein translation or by promoting target mRNA degradation. The hypothesis tested in this study was that PDGFs regulate genes expression by modulating microRNAs level in cancer cells. Methods: MicroRNA microarrays were performed to identify miR alterations after treatment of U118 glioblastoma cells with PDGF-AA and BB. Several time points were tested: 2, 6, 12, and 24 hour. Significance Analysis of Microarrays (SAM) was performed to compare expression level between different time points. Q-PCR was conducted to confirm the microarrays data. Pre-miR probe/miRCury LNA probe were transfected into cancer cells to over-express/knock down selected miRs. Western blots were used to detect miRs’ target proteins. Results: Candidate PDGF-inducible/repressible miRs were identified based on significant change in expression level after AA/BB treatment (p-value &amp;lt;0.01). Expression levels of 7 miRs were altered by PDGF AA and expression levels of 14 miRs were altered after PDGF BB treatment. By Q-PCR we showed that let 7d was repressed by PDGF-AA, but not by PDGF-BB in cancer cells (U118, C272 and U87) and in fibroblasts (WI38). Cyclin D1 is a known target of let7d. By overexpression and knock-down strategies we show that PDGF-AA induced cyclin D1 expression is mediated via repression of let7d. Q-PCR confirmed that miR-146b and miR-106b are inducible by PDGF-BB, but not by PDGF-AA in cancer cells (U118, C272 and U87) and in fibroblasts (WI38). MiR-146b induction by PDGF-BB is modulated via MAPK-dependent induction of Fos. A Fos binding element was identified in the promoter region of miR146b and Fos binding to this region in the presence of PDGF-BB was confirmed by chromatin immunoprecipitation. Several targets of miR146b are altered by PDGF in cancer cells. Conclusions: Our data demonstrate for the first time that PDGF signaling regulates expression of several critical oncogenic miRs which in turn alter target gene expression and function. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2041.

Platelet-Derived Growth Factor-AA Is an Essential and Autocrine Regulator of Vascular Endothelial Growth Factor Expression in Non–Small Cell Lung Carcinomas

It is widely accepted that angiogenesis is required for tumor progression. Vascular endothelial growth factor (VEGF) is a key molecule for tumor angiogenesis; however, its expressional regulation is not well understood during all stages of tumorigenesis. Using cell lines and surgical specimens of human non-small cell lung cancers (NSCLCs), we here show that platelet-derived growth factor-AA (PDGF-AA) is an essential autocrine regulator for VEGF expression. To directly assess the expression of PDGF-AA-dependent VEGF and its roles in tumorigenesis, we stably transfected established cell lines with their antisense genes. In addition, the levels of PDGF-AA and VEGF expression in surgical sections were measured and compared with clinicopathologic findings such as tumor size and patient prognosis. PDGF-AA tightly regulated VEGF expression and had a greater effect on tumor size and patient prognosis than did VEGF in both cell lines and surgical sections. PDGF-AA expression was not seen in the atypical adenomatous hyperplasia at all, whereas VEGF was occasionally seen. Furthermore, the frequency of VEGF expression was higher in advanced NSCLCs than in precancerous lesions, which was tightly correspondent to the results for PDGF-AA. These results indicate that PDGF-AA is an important regulator of the frequency and level of VEGF expression during the transition from a precancerous lesion to advanced cancer. The PDGF-AA/VEGF axis, therefore, may be a ubiquitous autocrine system for enhancing angiogenic signals, and PDGF-AA, and its related pathways could be a more efficient target of antiangiogenic therapy for cancers than VEGF and its pathways.

Role for TGF-beta1, FGF-2 and PDGF-AA in a myelination of CNS aggregate cultures enriched with macrophages.

The increase in myelin basic protein (MBP) synthesis observed in brain aggregate cultures supplemented with macrophages is reflected in elevated supernatant protein levels of the key promoters of oligodendrocyte proliferation, fibroblast growth factor-2 (FGF-2) and platelet-derived growth factor-AA (PDGF-AA), during the premyelinating phase. Although supernatant levels of transforming growth factor-beta1 (TGF-beta1), the most abundant growth factor produced at the transcriptional and translational levels by phagocytic macrophages, were reduced at this stage, it was the only growth factor for which mRNA expression was increased significantly in macrophage-enriched cultures. TGF-beta1, which supports oligodendrocyte differentiation, was increased in the supernatant of macrophage-enriched cultures only after the onset of myelinogenesis. Hence, standard cultures treated with TGF-beta1 during the premyelinating period reproduced effects of macrophage supplementation, inducing an increase in MBP synthesis and in PDGF-AA and FGF-2 bioavailability. A similar increase in MBP synthesis in PDGF-AA treated cultures emphasises its central role in oligodendrocyte progenitor proliferation. In contrast, FGF-2 blocked MBP synthesis in the cultures. In cultures treated with anti-TGF-beta1 antibody before or after the first detection of MBP, supernatant levels of TGF-beta1, FGF-2, and PDGF-AA were reduced with resultant inhibition of myelination. Paradoxically, supraphysiological TGF-beta1 treatment after the onset of myelination had the same effect on myelin accumulation. These results indicate an enabling and regulatory role for TGF-beta1 in oligodendrocyte development and, as a source of TGF-beta1, macrophages in the inflammatory multiple sclerosis lesion, may have the potential to promote remyelination by modulating the growth factor repertoire in demyelinating disease.

Differential PDGF secretion by graft and aortic SMC in response to oxidized LDL.

Smooth muscle cells (SMC) from prosthetic vascular grafts constitutively secrete higher levels of platelet-derived growth factor-AA (PDGF-AA) than aortic SMC. Lipid oxidation products accumulate in grafts and may stimulate PDGF production. The effect of oxidized low-density lipoprotein (oxLDL) on PDGF-AA secretion by aortic and graft SMC was compared. SMC isolated from canine thoracic aorta or Dacron thoracoabdominal grafts (n = 10) were incubated with native LDL or oxLDL (0-400 microg/ml) for 72 h. PDGF-AA in the conditioned medium was measured with enzyme-linked immunosorbent assay. OxLDL increased PDGF-AA production by graft SMC from 78 +/- 2 to 256 +/- 16 pg PDGF/microg DNA and aortic SMC from 21 +/- 1 to 40 +/- 2 pg PDGF/microg DNA. Native LDL had no effect. N-acetylcysteine inhibited oxLDL-induced PDGF increase. Both superoxide and H(2)O(2) stimulated PDGF secretion by graft SMC had little effect on aortic SMC. Our results suggest that PDGF production by graft (synthetic) SMC is more sensitive to stimulation by oxidative stress than aortic (contractile) SMC. Lipid oxidation products that accumulate in prosthetic vascular grafts can cause an oxidative stress, which stimulates PDGF production by graft SMC. PDGF can induce migration of aortic SMC onto the graft, contributing to the development of intimal hyperplasia.

Thrombin-induced mitogenesis of vascular SMC is partially mediated by autocrine production of PDGF-AA.

Previous studies have shown that alpha-thrombin (Thr) is a mitogen for cultured smooth muscle cells (SMC), but controversy exists concerning mechanisms of growth stimulation. The purpose of these studies was to determine whether autocrine production of platelet-derived growth factor-AA (PDGF-AA) mediated Thr-induced SMC mitogenesis. SMC derived from aortae of Sprague-Dawley rats were grown to confluence, growth arrested in serum-free medium, and treated. Conditioned medium (CM) was harvested by adding bovine serum albumin as a carrier and hirudin to neutralize residual Thr. Results demonstrated that CM from Thr-treated SMC (Thr CM) had increased mitogenic activity compared with control CM (Cnt CM) and that PDGF-AA levels were increased 12-fold in Thr CM compared with Cnt CM. The excess mitogenic activity in Thr CM was markedly inhibited by PDGF-AA-neutralizing antibodies. Cotreatment with Thr and PDGF-AA-neutralizing antibodies resulted in a 30% decrease in Thr-induced [3H]thymidine incorporation. These results demonstrate that autocrine production of PDGF-AA partially mediated Thr-induced SMC mitogenesis.