Expression and functional characterization of platelet-derived growth factor receptor-like gene

AIM:To investigate the role of platelet-derived growth factor receptor-like gene(PDGFRL)in the anti-cancer therapy for colorectal cancers(CRC).METHODS:PDGFRL mRNA and protein levels were measured by reverse transcription-polymerase chain reaction(RT-PCR)and immunohistochemistry in CRC and colorectal normal tissues.PDGFRL prokaryotic expression vector was carried out in Escherichia coli(E.coli),and purified by immobilized metal affinity chromatography.The effect of PDGFRL protein on CRC HCT-116 cells was detected by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide(MTT),clone counting,cell cycle,and wound healing assay.RESULTS:Both RT-PCR and immunohistochemistry showed that the expression of PDGFRL in colorectal normal tissues was higher than in cancer tissues.Recombinant pET22b-PDGFRL prokaryotic expression vector was successfully expressed in E.coli,and the target protein was expressed in the form of inclusion bodies.After purification and refolding,recombinant human PDGFRL(rhPDGFRL)could efficiently inhibit the proliferation and invasion of CRC HCT-116 cells detected by MTT,clone counting and wound healing assay.Moreover,rhPDGFRL arrested HCT-116 cell cycling at the G0/G1 phase.CONCLUSION:PDGFRL is a potential gene for application in the anti-cancer therapy for CRC.

Exogenous platelet-derived growth factor improves neurovascular unit recovery after spinal cord injury

The blood-spinal cord barrier plays a vital role in recovery after spinal cord injury.The neurovascular unit concept emphasizes the relationship between nerves and vessels in the brain,while the effect of the blood-spinal cord barrier on the neurovascular unit is rarely reported in spinal cord injury studies.Mouse models of spinal cord injury were established by heavy object impact and then immediately injected with plateletderived growth factor(80μg/kg)at the injury site.Our results showed that after platelet-derived growth factor administration,spinal cord injury,neuronal apoptosis,and blood-spinal cord barrier permeability were reduced,excessive astrocyte proliferation and the autophagyrelated apoptosis signaling pathway were inhibited,collagen synthesis was increased,and mouse locomotor function was improved.In vitro,human umbilical vein endothelial cells were established by exposure to 200μM H2O2.At 2 hours prior to injury,in vitro cell models were treated with 5 ng/mL platelet-derived growth factor.Our results showed that expression of blood-spinal cord barrier-related proteins,including Occludin,Claudin 5,andβ-catenin,was significantly decreased and autophagy was significantly reduced.Additionally,the protective effects of platelet-derived growth factor could be reversed by intraperitoneal injection of 80 mg/kg chloroquine,an autophagy inhibitor,for 3 successive days prior to spinal cord injury.Our findings suggest that platelet-derived growth factor can promote endothelial cell repair by regulating autophagy,improve the function of the blood-spinal cord barrier,and promote the recovery of locomotor function post-spinal cord injury.Approval for animal experiments was obtained from the Animal Ethics Committee,Wenzhou Medical University,China(approval No.wydw2018-0043)in July 2018.

Effect of recombinant human platelet-derived growth factor B on cat corneal endothelial cell viability mediated by adeno-associated virus

AIM: To transduce recombinant human platelet-derived growth factor B (PDGF-B) gene adeno-associated virus(AAV) to in vitro cultured cat corneal endothelial cell (CEC) and observe the effect of the expressed PDGF-BB protein on the viability of cat CEC. METHODS: Cat cornea endothelium was torn under microscope and rapidly cultivated in DMEM to form single layer CEC and the passage 2 endothelial cells were used in this study. The recombinant human PDGF-B gene AAV was constructed and transduced into cat CEC directly. Three groups were as following: blank control group, AAV control group and recombinant AAV group. At 24 hours, 48 hours, and 5 days after transduction, total RNA was extracted from the CEC by Trizol and the expression of PDGF-B gene was detected by fluorescence quantitative polymerase chain reaction. Viability of the transduced CEC was detected at 48 hours after transduction by MTT assay. Cell morphology was observed under inverted phase contrast microscope. RESULTS: With the torn endothelium culture technique, we rapidly got single layer cat CEC. At 24 hours, 48 hours and 5 days after transduction, fluorescence quantitative polymerase chain reaction showed there was no significant difference of the expressed PDGF-B gene mRNA between blank control group and AAV control group (P>0.05). In contrast, there were significant differences between two control groups and recombinant AAV group (P<0.05). MTT assay showed that in recombinant AAV group, the expressed PDGF-BB protein could promote the viability of cat CEC. Morphology observation showed at 48 hours after transduction, cells in CEC-AAV-PDGF-B group proliferated into bigger scales in regular triangle to hexagon shape with distinct boundary, while the number of cells was significantly less in the two control groups. CONCLUSION: The recombinant AAV-PDGF-B expresses biological active PDGF-BB protein in cat CEC, which promotes the viability and proliferation of cells.

Deficiency of platelet-derived growth factor receptor-α-positive cells in Hirschsprung's disease colon

AIM: To investigate whether the expression of plateletderived growth factor receptor-α-positive(PDGFRα^+)-cells is altered in Hirschsprung's disease(HD).METHODS: HD tissue specimens(n = 10) were collected at the time of pull-through surgery, while colonic control samples were obtained at the time of colostomy closure in patients with imperforate anus(n = 10). Immunolabelling of PDGFRα^+-cells was visualized using confocal microscopy to assess the distribution of these cells, while Western blot analysis was undertaken to quantify PDGFRα protein expression.RESULTS: Confocal microscopy revealed PDGFRα+-cells within the mucosa, myenteric plexus and smooth muscle in normal controls, with a marked reduction in PDGFRα^+-cells in the HD specimens. Western blotting revealed high levels of PDGFRα protein expression in normal controls, while there was a striking decrease in PDGFRα protein expression in the HD colon.CONCLUSION: These findings suggest that the altered distribution of PDGFRα^+-cells in both the aganglionic and ganglionic HD bowel may contribute to the motility dysfunction in HD.

Vascular endothelial growth factor/platelet-derived growth factor receptor pathway is involved in bone marrow mesenchymal stem cell differentiation and directional migration toward gliomas

BACKGROUND： Vascular endothelial growth factor （VEGF） induces bone marrow-derived mesenchymal stem cell （BMSC） differentiation into vascular endothelial-like cells and promotes BMSC migration toward gliomas. However, the molecular mechanisms by which VEGF induces BMSC differentiation and migration remain poorly understood. OBJECTIVE; To investigate the role of platelet-derived growth factor （PDGF） receptor （PDGFR） in BMSC differentiation and migration induced by VEGE DESIGN, TIME AND SETTING： A parallel, controlled, in vitro experiment was performed at the Molecular Neurobiology ＆ Neural Regeneration and Repairing Laboratory, Anhui Provincial Hospital of Anhui Medical University, China from June 2008 to March 2009. MATERIALS： U87 glioma cells were purchased from Shanghai Institutes for Biological Sciences; mouse anti-human PDGFR and VEGF receptor （VEGFR） monoclonal antibodies were purchased from Peprotech, USA. METHODS： Isolated BMSCs were precultured with neutralizing antibody for VEGFR-1, VEGFR-2, PDGFR-α, and PDGFR-β to block biological activity of related receptors, followed by induced differentiation with 50μg/L VEGF. BMSCs induced with 50μg/L VEGF alone served as the VEGF-induced group. The control group remained untreated. MAIN OUTCOME MEASURES： Cell surface markers were identified by flow cytometry; BMSC surface cytokine receptor expression was detected by reverse transcription-polymerase chain reaction; the Transwell model was used to observe cell migration. RESULTS： After blocking the PDGFR, VEGF did not induce BMSC cell surface marker CD-31 or von Willebrand factor （vWF） expression. However, inhibition with VEGF receptor blocking agents, VEGF induced BMSCs to express CD-31 and vWE Following inhibition of the PDGFR, the number of cells migrating through the polycarbonate membrane Transwell chamber was decreased, as well as the number of BMSCs migrating to glioma cells. However, through the use of VEGF receptor blocking agents, the number of migrating cells remained unchanged. VEGF preculture increased the number of BMSCs migrating to gliomas. CONCLUSION： VEGF interacts with PDGFRs on the BMSC surface to attract BMSC directional migration and induce BMSC differentiation. The VEGF/PDGFR pathway participates in BMSC directional migration to glioma. VEGF pretreatment increased efficiency of BMSC migration to glioma.

KIT and platelet-derived growth factor receptor α wild-type gastrointestinal stromal tumor associated with neurofibromatosis type 1: Two case reports

BACKGROUND Gastrointestinal stromal tumors(GISTs) associated with neurofibromatosis are uncommon compared to their gastrointestinal counterparts. Patients with neurofibromatosis type 1(NF-1) have an increased risk of developing gastrointestinal tumors, including rare types such as GIST.CASE SUMMARY A 60-year-old male Chinese patient was diagnosed with NF-1 10 years ago and presented with upper abdominal discomfort and black stools. Endoscopic ultrasonography and an enhanced abdominal computed tomography scan revealed a mass located 4 cm from the muscular layer of the descending duodenum. A 59-year-old Chinese woman who was diagnosed with NF-1 25 years ago presented with sudden unconsciousness and black stools. Multiple masses in the duodenum were noted by echogastroscopy and an enhanced abdominal computed tomography scan. Both patients presented with cutaneous neurofibromas. The histologic examination of tumors from both patients revealed spindle cells and low mitotic activity. Immunohistochemically, the tumor cells showed strong positivity for KIT(CD117), DOG-1, CD34, and Dehydrogenase Complex Subunit B, and negativity for SMA, desmin, S-100, and β-catenin. None of the six tumors from two patients had KIT exon 9, 11, 13, or 17 or platelet-derived growth factor receptor α exon 12 or 18 mutation, which is a typical finding for sporadic GISTs. None of the six tumors from the two patients had a BRAFV600 E mutation. The patients were alive and well during the follow-up period(range:0.6-5 yr).CONCLUSION There have been only a few previous reports of GISTs associated with NF-1.Although GISTs associated with NF-1 have morphologic and immunohistochemical similarities with GISTs, the pathogenesis, incidence,genetic background, and prognosis are not completely known. A medical history of NF-1 in a patient who has gastrointestinal bleeding or anemia and an intraabdominal mass with nonspecific computed tomography features may help in diagnosing GIST by virtue of the well-known association of these two entities.Molecular genetic studies of cases indicated that GISTs in NF-1 patients have a different pathogenesis than sporadic GISTs.

Effect of Retinoic acid on Platelet-derived Growth Factorand Lung Development in Newborn Rats

Summary: The influence of platelet-derived growth factor (PDGF) on lung development in newborn rats and the effect of retinoic acid (RA) on PDGF in lung development were investigated. Newborn Sprague-Dawley (SD) rats were randomly assigned to two groups: control group and RA group. The rats in RA group was intraperitoneally injected with all trans-retinoic acid (500 μg/kg every day) for consecutive 3 days after birth, while those in the control group were not subjected to intervention. Immunohistochemical assay was performed to locate the expression of PDGF. mRNA levels of PDGF were measured by reverse transcription polymerase chain reaction (RT-PCR) at age of 1, 3, 5, 7, 10, 14, 21 days. The method of radial alveolar counts (RAC) was used to measure the amount of the alveoli of the lungs. It was found that with increasing days, levels of PDGF-A and PDGF-B changed to verying degrees. RA could elevate significantly the expression levels of PDGF-A mRNA and protein (P<0.01), but not affect the expression levels of PDGF-B mRNA and protein markedly (P>0.05). It is suggested that PDGF might play an important role in lung development. RA can stimulate lung development through increasing the expression levels of PDGF-A mRNA and protein.

Effects of interleukin-1α on platelet-derived growth factor release from bovine cerebral microvascular endothelial cells

The present study showed that, interleukin-1α (IL-1α) stimulateal cultured bovine cerebral microvascular endothelial cells (BCMEC) releasing growth factor which promoted bovine cerebral microvascular smooth muscle cells (BCMSMC) proliferation in a dose-dependent manner. The mitogenic activity in conditioned medium of BCMEC stimulated by IL-1α was neutralized significantly by the antibody to platelet-derived growth factor (PDGF). Imperatorin (Imp), iso-Imperatorin (iso Imp) and 6-(α,α-phenylacetylpiperazinyl)phenyl-5-methyl-4,5-dihydro-3 (2H)-pyridazinone (PMDP) did not affect the releasing of PDGF from IL-1α stimulated BCMEC, but inhibited the promotion of PDGF on the proliferation of BCMSMC. We concluded that the promotion of IL-1α on the proliferation of BCMSMC should be mediated by some growth factors, such as PDGF.

Effects of IL-4 on cyclooxygenase-2 and platelet-derived growth factor in the lungs of COPD rats

Objective： To explore the role of interleukin 4（IL-4）, expressions of cyclooxygenase-2 （COX-2） and platelet-derived growth factor （PDGF） in the model of chronic obstructive pulmonary disease （COPD）, in the lungs of rats. Methods： Male Wistar rats were used to build up the model of COPD. Rats were randomly divided into the control group and model group, the IL-4 group and the dexamethasone group. The expressions of COX-2, PDGF-A and PDGF-B in the lung tissue were detected by western blotting and RT-PCR. Results： The expressions of COX-2, PDGF-A and PDGF-B in the model group were increased significantly. Those expressions in the IL-4 and dexamethasone group were notably decreased. Conclusion： IL-4 and dexamethasone could interfere in the establishment of COPD. The expressions of COX-2 and PDGF in the lung tissue of COPD were increased significantly and IL-4 and dexamethasone could decrease those expressions.

Expression of NG2 and platelet-derived growth facto receptor alpha in the developing neonatal rat brain

Platelet-derived growth factor receptor alpha （PDGFRct） is a marker of oligodendrocyte precursor cells in the central nervous system. NG2 is also considered a marker of oligodendrocyte precursor cells. However, whether there are differences in the distribution and morphol- ogy of oligodendrocyte precursor cells labeled by NG2 or PDGFRa in the developing neonatal rat brain remains unclear. In this study, by immunohistochemical staining, NG2 positive （NG2＋） cells were ubiquitous in the molecular layer, external pyramidal layer, internal pyramidal layer, and polymorphic layer of the cerebral cortex, and corpus callosum, external capsule, piriform cortex, and medial septal nucleus. NG2~ cells were stellate or fusiform in shape with long processes that were progressively decreased and shortened over the course of brain development. The distribution and morphology of PDGFRct positive （PDGFRa＋） cells were coincident with NG2＋ cells. The co- localization of NG2 and PDGFRu in the cell bodies and processes of some cells was confirmed by double immunofluorescence labeling. Moreover, cells double-labeled for NG2 and PDGFRa were predominantly in the early postnatal stage of development. The numbers of NG2＋/PDGFRa＋ cells and PDGFRa＋ cells decreased, but the number of NG2＋ cells increased from postnatal days 3 to 14 in the developing brain. In addition, amoeboid microglial cells of the corpus callosum, newborn brain macrophages in the normal developing brain, did not express NG2 or PDGFRu, but NG2 expression was detected in amoeboid microglia after hypoxia. The present results suggest that NG2 and PDGFRct are specific markers of oligodendrocyte precursor cells at different stages during early development. Additionally, the NG2 protein is involved in inflammatory and pathological processes of amoeboid microglial cells.

Basic fibroblast growth factor gene transfection in repair of internal carotid artery aneurysm wall

Surgery or interventional therapy has some risks in the treatment of cerebral aneurysm. We established an internal carotid artery aneurysm model by dripping elastase in the crotch of the right internal and external carotid arteries of New Zealand rabbits. Following model induction, lentivirus carrying basic fibroblast growth factor was injected through the ear vein. We found that the longer the action time of the lentivirus, the smaller the aneurysm volume. Moreover, platelet-derived growth factor expression in the aneurysm increased, but smooth muscle 22 alpha and hypertension-related gene 1 mRNA expression decreased. At 1,2, 3, and 4 weeks following model establishment, following 1 week of injection of lentivirus carrying basic fibroblast growth factor, the later the intervention time, the more severe the blood vessel damage, and the bigger the aneurysm volume, the lower the smooth muscle 22 aJpha and hypertension-related gene ~ mRNA expression. Simultaneously, platelet-derived growth factor expression decreased. These data suggest that recombinant lentivirus carrying basic fibroblast growth factor can repair damaged cells in the aneurysmal wall and inhibit aneurysm dynamic growth, and that the effect is dependent on therapeutic duration.

Electroacupuncture upregulated platelet derived growth factor expression in spared dorsal root ganglion of cats

A bilateral spared dorsal root ganglion model was established in healthy adult cats by bilateral resection of L1-5 and L7-S2 dorsal root ganglia. L6 dorsal root ganglia were spared. Zusanfi （ST36） and Xuanzhong （BL39） or Futu （ST32） and Sanyinjiao （SP6） were alternatively electro-stimulated on the right leg. Immunohistochemical staining of anti-serum platelet-derived growth factor demonstrated that the number of total neurons and medium-small sized platelet-derived growth factor positive neurons was significantly decreased on the 7~ day following injury. After 7 days of acupuncture, the total number of positive and large neurons staining for platelet-derived growth factor on the acupuncture side significantly increased compared to the non-acupuncture side. After acupuncture for 14 days, the total positive and medium-small sized neurons significantly increased compared with the non-acupuncture side. Results indicate that acupuncture promoted the synthesis of platelet-dedved growth factor in spared dorsal root ganglia.

Myeloid neoplasm with eosinophilia and rearrangement of plateletderived growth factor receptor beta gene in children: Two case reports

BACKGROUND Myeloid neoplasm(MN)with eosinophilia and rearrangement of platelet-derived growth factor receptor beta(PDGFRB)shows a good therapeutic response to imatinib in adults.MN is rarely found in children,and the efficacy of imatinib on pediatric patients remain unclear.CASE SUMMARY We report 2 pediatric cases diagnosed with MN with eosinophilia and PDGFRB rearrangement who were treated with imatinib.Case 1 was a 1-year-old girl admitted to the hospital because of“abdominal distension with hyperleukocytosis for 3 mo”.She had leukocytosis,anemia,and eosinophilia(the absolute eosinophil count(AEC)was 8960/μL),and her fluorescence in situ hybridization(FISH)test revealed that PDGFRB rearrangement was detected in 70%of 500 interphase cells.Case 2 was a 2-year-old girl admitted to the hospital because of“recurrent fever and rashes for 1 mo”.Her blood cell count showed an AEC of 3540/μL.The FISH test revealed that PDGFRB rearrangement was detected in 71%of 500 interphase cells.Both patients were diagnosed as MN with eosinophilia and PDGFRB rearrangement.Imatinib was added into their treatment regimen.As expected,complete hematologic remission was achieved after 1 mo of treatment,and symptoms disappeared.CONCLUSION Although MN with eosinophilia and PDGFRB rearrangement usually occurs in adults,it can be found in children.The therapeutic benefits of imatinib in these 2 pediatric patients were consistent with its reported effects in adult patients.

Effects of ribozyme targeting platelet-derived growth factor receptor β subunit gene on the proliferation and apoptosis of hepatic stellate cells in vitro

Background Activation and proliferation of hepatic stellate cells (HSC) is essentially involved in the development and progression of hepatic fibrosis. The most potent growth factor for HSC is platelet-derived growth factor receptor (PDGF) and PDGF receptor β subunit (PDGFR-β) is the predominant signal transduction pathyway of PDGF which is overexpressed in activated HSC. This study investigated the cleavage activity of hammerhead ribozyme targeting PDGFR-β mRNA in HSC and the effect on biological characteristics of HSC.Methods Expression vector of anti-PDGFR-β ribozyme was constructed and transfected into rat activated HSC with lipofectamin. The positive cell clones were gained by G418 selection. The expression of PDGFR-β, α-smooth muscle actin, and typeⅠand type Ⅲ collagen were detected by using Northern blot, Western blot and immunocytochemical staining, respectively. The cell proliferation was determined with MTT colorimetric assay. The cell apoptosis was analyzed by using flow cytometry, acridine orange fluorescence vital staining and transmission electron microscopy.Results The expression of PDGFR-β at mRNA and protein level was markedly reduced in ribozyme-transfected HSC by 49%-57% ( P <0.05-0.01). The proliferation and α-smooth muscle actin expression of ribozyme-transfected HSC were significantly decreased ( P <0.05-0.01), and the type Ⅰ and type Ⅲ collagen synthesis were also reduced ( P <0.01). In addition, the proliferative response of ribozyme-transfected HSC to PDGF BB was significantly inhibited. Otherwise, the apoptotic cells were significantly increased in ribozyme-transfected HSC ( P <0.01), and typical apoptotic cells could be found under transmission electron microscopy.Conclusions The anti-PDGFR-β ribozyme effectively cleaved the target RNA and significantly inhibited its expression, which blocked the signal transduction of PDGF at receptor level, inhibited HSC proliferation and collagen synthesis, and induced HSC apoptosis. These results suggest that inhibiting PDGFR-β expression of HSC may be a new target for the therapy of liver fibrogenesis, and ribozyme may be a useful tool for inhibiting PDGFR-β expression.

Changes in the expression of platelet-derived growth factor in astrocytes in diabetic rats with spinal cord injury

Background Prospective mortality studies in the United States revealed that the mortality was elevated in diabetics compared to normal individuals following chronic spinal cord injury （SCI）. Our study was conducted to investigate the levels of platelet-derived growth factor （PDGF） of astrocytes in SCI in streptozotocin （STZ）-induced diabetic rats. Methods Thirty male Sprague-Dawley （SD） rats were randomly divided into 3 groups： SCI group, diabetic SCI group, and sham operation control group. We employed STZ-induced diabetic SD rats and a weight-drop contusion SCI model. The rats were sacrificed on day 7 after the induction of SCI. Immunohistochemistry and Western blotting analysis were used to detect the PDGF expression level. Basso, Beattie and Bresnahan locomotor rating scale （BBB） was also used to evaluate the neurological recovery level of the rats. Results PDGF positive astrocyte numbers were significantly higher and PDGF staining was more intensive in astrocytes in the SCI group than in the diabetic SCI group （P〈0.05）. The diabetic SCI group showed a slower recovery of motor function with a lower BBB score 7 days after acute spinal injury. Conclusions PDGF is an important factor for the recovery of neurological function after acute spinal injury and hyperglycemia in diabetic rats could depress the expression of PDGF in injured spinal cord. This may help to explain the slower recovery and higher mortality in diabetics after SCI.

Role of RhoA in platelet-derived growth factor-BB-induced migration of rat hepatic stellate cells

Background Although the migration of hepatic stellate cells （HSCs） is essential for hepatic fibrotic response, the detailed mechanisms involved are poorly understood. The aim of this study was to examine the role of Rho GTPases （especially RhoA） in platelet-derived growth factor （PDGF）-BB-induced migration of HSCs. Methods The migration of primary rat HSCs was evaluated using transwell Boyden chamber, while cytoskeletal changes were visualized by immunofluorescence staining of intracellular actins and vinculin. Quantitative real-time PCR and Western blotting analysis were used to detect the expression of Rho GTPases （RhoA, Racl and Cdc42） within HSCs and their activation was determined by glutathione S-transferase pull-down assay. Finally, the effects of RhoA on PDGF-BB-induced cell migration and cytoskeletal remodeling were analyzed using HSC-T6 cells stably transfected with constitutively active （CA, Q63L） or dominant negative （DN, T19N） RhoA mutants. Data were analyzed using SPSS 16.0 software. Student＇s t test was used to analyze differences between two groups and one-way analysis of variance （ANOVA） was used among multiple groups. Results Rapid cytoskeletal remodeling led to a significant increase in the motility of primary rat HSCs after haptotactic （direct） and chemotactic （indirect） stimulation by PDGF-BB： PDGF-BB caused a dramatic elevation in the levels of both total and active RhoA protein. However, the levels of mRNA for Rho GTPases, including RhoA, Racl and Cdc42, were unaffected. Furthermore, PDGF-BB induced increased formation of stress fibers and focal adhesions in HSC-T6 cells transfected with CA-RhoA, but not in HSC-T6 transfected with DN-RhoA. Surprisingly, both CA- and DN-RhoA-transfected HSC-T6 cells showed decreased migratory potential in the absence or presence of PDGF-BB compared with controls. Conclusions PDGF-BB induced cytoskeletal remodeling in rat HSCs and promoted their migration via regulation of intracellular RhoA. RhoA may be one of the determinants in PDGF-BB-induced HSC miaration.

A partition-type tubular scaffold loaded with PDGF-releasing microspheres for spinal cord repair facilitates the directional migration and growth of cells

The best tissue-engineered spinal cord grafts not only match the structural characteristics of the spinal cord but also allow the seed cells to grow and function in situ.Platelet-derived growth factor（PDGF） has been shown to promote the migration of bone marrow stromal cells;however,cytokines need to be released at a steady rate to maintain a stable concentration in vivo.Therefore,new methods are needed to maintain an optimal concentration of cytokines over an extended period of time to effectively promote seed cell localization,proliferation and differentiation.In the present study,a partition-type tubular scaffold matching the anatomical features of the thoracic 8–10 spinal cord of the rat was fabricated using chitosan and then subsequently loaded with chitosan-encapsulated PDGF-BB microspheres（PDGF-MSs）.The PDGF-MS-containing scaffold was then examined in vitro for sustained-release capacity,biocompatibility,and its effect on neural progenitor cells differentiated in vitro from multilineage-differentiating stress-enduring cells（MUSE-NPCs）.We found that pre-freezing for 2 hours at-20°C significantly increased the yield of partition-type tubular scaffolds,and 30 μL of 25% glutaraldehyde ensured optimal crosslinking of PDGF-MSs.The resulting PDGF-MSs cumulatively released 52% of the PDGF-BB at 4 weeks in vitro without burst release.The PDGF-MS-containing tubular scaffold showed suitable biocompatibility towards MUSE-NPCs and could promote the directional migration and growth of these cells.These findings indicate that the combination of a partition-type tubular scaffold,PDGF-MSs and MUSENPCs may be a promising model for the fabrication of tissue-engineered spinal cord grafts.

A novel aptasensor based on 3D-inorganic hybrid composite as immobilized substrate for sensitive detection of platelet-derived growth factor

A novel electrochemical detection approach for platelet-derived growth factor（PDGF） via ＂sandwich＂structure is reported in this paper. 3D-4MgCO3 Mg（OH）2 4H2O-Au NPs inorganic hybrid composite was utilized as immobilized substrate for sensitive PDGF detection and Pt-Au bimetallic nanoparticles were labelled on PDGF aptamer to indirectly detect PDGF for the first time. The proposed aptasensor exhibited a high catalytic efficiency towards reduction of H2O2, hence the sensitive detection of PDGF was achieved.Results showed that the aptasensor exhibited excellent linear response to PDGF, in the range of 0.1 pg/m L–10 ng/m L（4 fmol/L–400 pmol/L）, with detection limit of 0.03 pg/m L（1.2 fmol/L）.

The relationship between platelet-derived growth factor expression and angiogenesis/lymphangiogenesis in cervical cancer

This paper is aimed to examine if changes in platelet-derived growth factor(PDGF)expression at different stages of cervical cancer are related to the variation in blood vessel density(BVD)and lymphatic vessel density(LVD)to evaluate the relationship between PDGF expression and stages and metastasis of cervical cancer.Polymerase chain reaction(PCR)and RT-PCR were used to detect the expression levels of PDGF in 45 cervical cancer tissue samples(the experimental group).The samples were immunohistochemically stained with mono-clonal antibodies D2-40 and CD34,and BVD and LVD were measured.The expressions of PDGF-A,-B,and-D were all higher in the experimental group than in the control group(P<0.05);no significant difference was found in the expression of PDGF-C between the experi-mental group and the control group(P>0.05).PDGF-A and-B expression was positively related with BVD and LVD(P<0.01,R=0.49,0.527,0.327,0.68).The expression levels of PDGF-C and-D were not significantly related with BVD and LVD.At the early stage of cervical cancer,BVD and LVD were significantly higher than in the controls(P<0.01).The BVD and LVD in tissues in the surrounding areas of cervical cancer were significantly higher than in tissues at cancer center,and LVD was related to lymph node metastasis(P<0.001).BVD and LVD were not associated with the differentiation and pathological stages of cervical cancer.The expressions of PDGF-A,-B,and-D in cervical cancer were closely related with the clinical stages of cervical cancer.PDGF-A and-B were intimately associated with the lymph node metastasis and prognosis of cervical cancer.

Modulation of transforming growth factor β to platelet-derived growth factor receptor-a of human osteoblasts

To investigate the mechanism and thesignificance of TGR in modulating the expression ofPlatelet-Derived Growth Factor Receptor-α (PDGFR-α)in human osteoblasts. Methods The osteoblasts were isolated from humanfetal calvaria. The percentage of cell increase (PCI) inevery 4 hours was calculated to demonstrate theproliferation of osteoblasts affected by PDGF-AA andTGFβ. The osteoblasts were cultured with TGFβ for 24hours and with PDGF-AA for another 24 hours, and thecells proliferation was shown by PCI too. Theosteoblasts were cultured with TGFβfor 24 h, and thePDGFR-α of the cells were measured byimmunofluorescent analysis. Results PCI was increased by 48.2% and 22.4%after PDGF-AA and TGFβ were added into the mediumfor 24 hours respectively (P < 0.05 ), and PCIdecreased after the removal of the two cytokines.Preincubated with TGFβfor 24 hours and thenstimulated with PDGF-AA, PCI grew slowly. TGFβdownregulated the expression of the PDGFR-a. Conclusion TGFβ can downregulate the mitogenesisof PDGF-AA by lowering the number of PDGFR-α.