Cold to Hot: Tumor Immunotherapy by Promoting Vascular Normalization Based on PDGFB Nanocomposites

Immunotherapy is a promising cancer therapeutic strategy. However, the "cold" tumor immune microenvironment (TIME), characterized by insufficient immune cell infiltration and immunosuppressive status, limits the efficacy of immunotherapy. Tumor vascular abnormalities due to defective pericyte coverage are gradually recognized as a profound determinant in "cold" TIME establishment by hindering immune cell trafficking. Recently, several vascular normalization strategies by improving pericyte coverage have been reported, whereas have unsatisfactory efficacy and high rates of resistance. Herein, a combinatorial strategy to induce tumor vasculature-targeted pericyte recruitment and zinc ion-mediated immune activation with a platelet-derived growth factor B (PDGFB)-loaded, cyclo (Arg-Gly-Asp-D-Phe-Lys)-modified zeolitic imidazolate framework 8 (PDGFB@ZIF8-RGD) nanoplatform is proposed. PDGFB@ZIF8-RGD effectively induced tumor vascular normalization, which facilitated trafficking and infiltration of immune effector cells, including natural killer (NK) cells, M1-like macrophages and CD8+ T cells, into tumor microenvironment. Simultaneously, vascular normalization promoted the accumulation of zinc ions inside tumors to trigger effector cell immune activation and effector molecule production. The synergy between these two effects endowed PDGFB@ZIF8-RGD with superior capabilities in reprogramming the "cold" TIME to a "hot" TIME, thereby initiating robust antitumor immunity and suppressing tumor growth. This combinatorial strategy for improving immune effector cell infiltration and activation is a promising paradigm for solid tumor immunotherapy.

Microvascular smooth muscle cells exhibit divergent phenotypic switching responses to platelet-derived growth factor and insulin-like growth factor 1

OBJECTIVE

Vascular smooth muscle cell (VSMC) phenotypic switching is critical for normal vessel formation, vascular stability, and healthy brain aging. Phenotypic switching is regulated by mediators including platelet derived growth factor (PDGF)-BB, insulin-like growth factor (IGF-1), as well as transforming growth factor-β (TGF-β) and endothelin-1 (ET-1), but much about the role of these factors in microvascular VSMCs remains unclear.

METHODS

We used primary rat microvascular VSMCs to explore PDGF-BB- and IGF-1-induced phenotypic switching.

RESULTS

PDGF-BB induced an early proliferative response, followed by formation of polarized leader cells and rapid, directionally coordinated migration. In contrast, IGF-1 induced cell hypertrophy, and only a small degree of migration by unpolarized cells. TGF-β and ET-1 selectively inhibit PDGF-BB-induced VSMC migration primarily by repressing migratory polarization and formation of leader cells. Contractile genes were downregulated by both growth factors, while other genes were differentially regulated by PDGF-BB and IGF-1.

CONCLUSIONS

These studies indicate that PDGF-BB and IGF-1 stimulate different types of microvascular VSMC phenotypic switching characterized by different modes of cell migration. Our studies are consistent with a chronic vasoprotective role for IGF-1 in VSMCs in the microvasculature while PDGF is more involved in VSMC proliferation and migration in response to acute activities such as neovascularization. Better understanding of the nuances of the phenotypic switching induced by these growth factors is important for our understanding of a variety of microvascular diseases.

Bone-derived PDGF-BB drives brain vascular calcification in male mice

Brain vascular calcification is a prevalent age-related condition often accompanying neurodegenerative and neuroinflammatory diseases. The pathogenesis of large-vessel calcifications in peripheral tissue is well studied, but microvascular calcification in the brain remains poorly understood. Here, we report that elevated platelet-derived growth factor BB (PDGF-BB) from bone preosteoclasts contributed to cerebrovascular calcification in male mice. Aged male mice had higher serum PDGF-BB levels and a higher incidence of brain calcification compared with young mice, mainly in the thalamus. Transgenic mice with preosteoclast-specific Pdgfb overexpression exhibited elevated serum PDGF-BB levels and recapitulated age-associated thalamic calcification. Conversely, mice with preosteoclast-specific Pdgfb deletion displayed diminished age-associated thalamic calcification. In an ex vivo cerebral microvascular culture system, PDGF-BB dose-dependently promoted vascular calcification. Analysis of osteogenic gene array and single-cell RNA-Seq (scRNA-Seq) revealed that PDGF-BB upregulated multiple osteogenic differentiation genes and the phosphate transporter Slc20a1 in cerebral microvessels. Mechanistically, PDGF-BB stimulated the phosphorylation of its receptor PDGFRβ (p-PDGFRβ) and ERK (p-ERK), leading to the activation of RUNX2. This activation, in turn, induced the transcription of osteoblast differentiation genes in PCs and upregulated Slc20a1 in astrocytes. Thus, bone-derived PDGF-BB induced brain vascular calcification by activating the p-PDGFRβ/p-ERK/RUNX2 signaling cascade in cerebrovascular cells.

Isolation and Cultivation of Vascular Smooth Muscle Cells from the Mouse Circle of Willis

INTRODUCTION

Culturing cerebrovascular smooth muscle cells (CVSMCs) in vitro can provide a model for studying many cerebrovascular diseases. This study describes a convenient and efficient method to obtain mouse CVSMCs by enzyme digestion.

METHODS

Mouse circle of Willis was isolated, digested, and cultured with platelet-derived growth factor-BB (PDGF-BB) to promote CVSMC growth, and CVSMCs were identified by morphology, immunofluorescence analysis, and flow cytometry. The effect of PDGF-BB on vascular smooth muscle cell (VSMC) proliferation was evaluated by cell counting kit (CCK)-8 assay, morphological observations, Western blotting, and flow cytometry.

RESULTS

CVSMCs cultured in a PDGF-BB-free culture medium had a typical peak-to-valley growth pattern after approximately 14 days. Immunofluorescence staining and flow cytometry detected strong positive expression of the cell type-specific markers alpha-smooth muscle actin (α-SMA), smooth muscle myosin heavy chain 11 (SMMHC), smooth muscle protein 22 (SM22), calponin, and desmin. In the CCK-8 assay and Western blotting, cells incubated with PDGF-BB had significantly enhanced proliferation compared to those without PDGF-BB.

CONCLUSION

We obtained highly purified VSMCs from the mouse circle of Willis using simple methods, providing experimental materials for studying the pathogenesis and treatment of neurovascular diseases in vitro. Moreover, the experimental efficiency improved with PDGF-BB, shortening the cell cultivation period.

Hyaluronic acid and proteoglycan link protein 1 suppresses platelet‑derived growth factor-BB-induced proliferation, migration, and phenotypic switching of vascular smooth muscle cells

The development of atherosclerotic cardiovascular disease is associated with the phenotypic switching of vascular smooth muscle cells (SMCs) from a contractile to a synthetic state, leading to cell migration and proliferation. Platelet‑derived growth factor‑BB (PDGF‑BB) modulates this de-differentiation by initiating a number of biological processes. In this study, we show that gene expression of hyaluronic acid (HA) and proteoglycan link protein 1 (HAPLN1) was upregulated during differentiation of human aortic SMCs (HASMCs) into a contractile state, but downregulated upon during PDGF-BB-induced dedifferentiation. This is the first study showing that the treatment of HASMCs with full-length recombinant human HAPLN1 (rhHAPLN1) significantly reversed PDGF-BB-induced decrease in the protein levels of contractile markers (SM22α, α-SMA, calponin, and SM-MHC), and inhibited the proliferation and migration of HASMCs induced by PDGF-BB. Furthermore, our results show that rhHAPLN1 significantly inhibited the phosphorylation of FAK, AKT, STAT3, p38 MAPK and Raf mediated by the binding of PDGF-BB to PDGFRβ. Together, these results indicated that rhHAPLN1 can suppress the PDGF-BB-stimulated phenotypic switching and subsequent de-differentiation of HASMCs, highlighting its potential as a novel therapeutic target for atherosclerosis and other vascular diseases. [BMB Reports 2023; 56(8): 445-450].

Hyaluronic acid and proteoglycan link protein 1 suppresses platelet‑derived growth factor-BB-induced proliferation, migration, and phenotypic switching of vascular smooth muscle cells

The development of atherosclerotic cardiovascular disease is associated with the phenotypic switching of vascular smooth muscle cells (SMCs) from a contractile to a synthetic state, leading to cell migration and proliferation. Platelet‑derived growth factor‑BB (PDGF‑BB) modulates this de-differentiation by initiating a number of biological processes. In this study, we show that gene expression of hyaluronic acid (HA) and proteoglycan link protein 1 (HAPLN1) was upregulated during differentiation of human aortic SMCs (HASMCs) into a contractile state, but downregulated upon during PDGF-BB-induced dedifferentiation. This is the first study showing that the treatment of HASMCs with full-length recombinant human HAPLN1 (rhHAPLN1) significantly reversed PDGF-BB-induced decrease in the protein levels of contractile markers (SM22α, α-SMA, calponin, and SM-MHC), and inhibited the proliferation and migration of HASMCs induced by PDGF-BB. Furthermore, our results show that rhHAPLN1 significantly inhibited the phosphorylation of FAK, AKT, STAT3, p38 MAPK and Raf mediated by the binding of PDGF-BB to PDGFRβ. Together, these results indicated that rhHAPLN1 can suppress the PDGF-BB-stimulated phenotypic switching and subsequent de-differentiation of HASMCs, highlighting its potential as a novel therapeutic target for atherosclerosis and other vascular diseases. [BMB Reports 2023; 56(8): 445-450].

Chronic Morphine Modulates PDGFR-β and PDGF-B Expression and Distribution in Dorsal Root Ganglia and Spinal Cord in Male Rats

The analgesic effect of opioids decreases over time due to the development of analgesic tolerance. We have shown that inhibition of the platelet-derived growth factor beta (PDGFR-β) signaling eliminates morphine analgesic tolerance in rats. Although the PDGFR-β and its ligand, the platelet-derived growth factor type B (PDGF-B), are expressed in the substantia gelatinosa of the spinal cord (SG) and in the dorsal root ganglia (DRG), their precise distribution within different cell types of these structures is unknown. Additionally, the impact of a tolerance-mediating chronic morphine treatment, on the expression and distribution of PDGF-B and PDGFR-β has not yet been studied. Using immunohistochemistry (IHC), we found that in the spinal cord, PDGFR-β and PDGF-B were expressed in neurons and oligodendrocytes and co-localized with the mu-opioid receptor (MOPr) in opioid naïve rats. PDGF-B was also found in microglia and astrocytes. Both PDGFR-β and PDGF-B were detected in DRG neurons but not in spinal primary afferent terminals. Chronic morphine exposure did not change the cellular distribution of PDGFR-β or PDGF-B. However, PDGFR-β expression was downregulated in the SG and upregulated in the DRG. Consistent with our previous finding that morphine caused tolerance by inducing PDGF-B release, PDGF-B was upregulated in the spinal cord. We also found that chronic morphine exposure caused a spinal proliferation of oligodendrocytes. The changes in PDGFR-β and PDGF-B expression induced by chronic morphine treatment suggest potential mechanistic substrates underlying opioid tolerance.

A Promising Candidate in Tendon Healing Events—PDGF-BB

Tendon injuries are one of the most common musculoskeletal disorders for which patients seek medical aid, reducing not only the quality of life of the patient but also imposing a significant economic burden on society. The administration of growth factors at the wound site is a feasible solution for enhancing tendon healing. Platelet-derived growth factor-BB (PDGF-BB) has a well-defined safety profile compared to other growth factors and has been approved by the Food and Drug Administration (FDA). The purpose of this review is to summarize the role of PDGF-BB in tendon healing through a comprehensive review of the published literature. Experimental studies suggest that PDGF-BB has a positive effect on tendon healing by enhancing inflammatory responses, speeding up angiogenesis, stimulating tendon cell proliferation, increasing collagen synthesis and increasing the biomechanics of the repaired tendon. PDGF-BB is regarded as a promising candidate in tendon healing. However, in order to realize its full potential, we still need to carefully consider and study key issues such as dose and application time in the future, so as to explore further applications of PDGF-BB in the tendon healing process.

CFTR Suppresses Neointimal Formation Through Attenuating Proliferation and Migration of Aortic Smooth Muscle Cells

ABSTRACT

Cystic fibrosis transmembrane conductance regulator (CFTR) plays important roles in arterial functions and the fate of cells. To further understand its function in vascular remodeling, we examined whether CFTR directly regulates platelet-derived growth factor-BB (PDGF-BB)-stimulated vascular smooth muscle cells (VSMCs) proliferation and migration, as well as the balloon injury-induced neointimal formation. The CFTR adenoviral gene delivery was used to evaluate the effects of CFTR on neointimal formation in a rat model of carotid artery balloon injury. The roles of CFTR in PDGF-BB-stimulated VSMC proliferation and migration were detected by mitochondrial tetrazolium assay, wound healing assay, transwell chamber method, western blot, and qPCR. We found that CFTR expression was declined in injured rat carotid arteries, while adenoviral overexpression of CFTR in vivo attenuated neointimal formation in carotid arteries. CFTR overexpression inhibited PDGF-BB-induced VSMC proliferation and migration, whereas CFTR silencing caused the opposite results. Mechanistically, CFTR suppressed the phosphorylation of PDGF receptor β, serum and glucocorticoid-inducible kinase 1, JNK, p38 and ERK induced by PDGF-BB, and the increased mRNA expression of matrix metalloproteinase-9 and MMP2 induced by PDGF-BB. In conclusion, our results indicated that CFTR may attenuate neointimal formation by suppressing PDGF-BB-induced activation of serum and glucocorticoid-inducible kinase 1 and the JNK/p38/ERK signaling pathway.

Conditioned medium from human uterine cervical stem cells regulates oxidative stress and angiogenesis of retinal pigment epithelial cells

INTRODUCTION

Retinal homeostasis is essential to avoid retinal pigment epithelium (RPE) damage resulting in photoreceptor death and blindness. Mesenchymal stem cells-based cell therapy could contribute to the maintenance of the retinal homeostasis. We have explored the effect of human uterine cervical stem cells (hUCESCs) conditioned medium (hUCESC-CM) on RPE cells under oxidative stress condition.

METHODS

ARPE-19 cells were treated with hydrogen peroxide (H2O2) in presence or absence of hUCESC-CM. qRT-PCR and Western blot were used to evaluate the expression of oxidative stress (HO-1, GCLC and HSPB1) and vasculogenesis (VEGFA, PDGFA and PDGFB) related factors. Also, we assessed in vitro effects of hUCESC-CM on endothelial cells (HUVEC) tube formation.

RESULTS

mRNA expression of HO-1, GCLC, HSPB1, VEGFA, PDGFA and PDGFB were significantly increased in ARPE-19 cells treated with H2O2 + hUCESC-CM compared to cells treated with H2O2 only. Regarding the tube formation assay, HUVEC treated with supernatant from ARPE-19 cells treated with H2O2 + hUCESC-CM showed a significant increase in average vessel length, number of capillary-like junctions and average of vessels area compared with HUVEC treated with supernatant from ARPE-19 cells treated with H2O2 only.

CONCLUSION

Our results show potential therapeutic effects of hUCESC-CM on RPE, such as protection from damage by oxidative stress, stimulation of detoxifying genes and a better vascularization.

Platelet-derived growth factor-BB regenerates functional periodontal ligament in the tooth replantation

Tooth ankylosis is a pathological condition of periodontal ligament (PDL) restoration after tooth replantation. Platelet-derived growth factor-BB (PDGF-BB) has been proposed as a promising factor for preventing tooth ankylosis. Using rat tooth replantation model, we investigated whether PDGF-BB accelerates the repair of PDL after tooth replantation without ankylosis, and its molecular mechanisms. In PDGF-BB pretreated replanted teeth (PDGF-BB group), ankylosis was markedly reduced and functionally organized PDL collagen fibers were restored; the mechanical strength of the healing PDL was restored to an average of 76% of that in non-replanted normal teeth at 21 days. The numbers of PDGF-Rβ- and BrdU-positive cells in the periodontal tissues of the PDGF-BB group were greater than those of atelocollagen pretreated replanted teeth (AC group). Moreover, in the PDGF-BB group, the periodontal tissues had fewer osteocalcin-positive cells and decreased number of nuclear β-catenin-positive cells compared to those in the AC group. In vitro analyses showed that PDGF-BB increased the proliferation and migration of human periodontal fibroblasts. PDGF-BB downregulated mRNA expressions of RUNX2 and ALP, and inhibited upregulatory effects of Wnt3a on β-catenin, AXIN2, RUNX2, COL1A1, and ALP mRNA expressions. These findings indicate that in tooth replantation, topical PDGF-BB treatment enhances cell proliferation and migration, and inhibits canonical Wnt signaling activation in bone-tooth ankylosis, leading to occlusal loading of the PDL tissues and subsequent functional restoration of the healing PDL. This suggests a possible clinical application of PDGF-BB to reduce ankylosis after tooth replantation and promote proper regeneration of PDL.

Inhibition of PDGF-BB-induced proliferation and migration in VSMCs by proanthocyanidin A2: Involvement of KDR and Jak-2/STAT-3/cPLA2 signaling pathways

Proanthocyanidin A2 (PA2), one of A-type proanthocyanidins, has been shown to harbor a broad spectrum of pharmacological activities, including anti-inflammatory, antioxidant, anti-HIV, anti-CDV and anti-?-glucosidase activities. However, little is known about the role for PA2 in regulating PDGF-induced VSMC proliferation and migration. In the present study, we investigated the possible effects of PA2 on PDGF-BB-induced proliferation, migration and inflammation in VSMCs in vitro to mimic a postangioplasty PDGF shedding condition. Herein, the data clearly show that PA2 markedly inhibited proliferation, migration and inflammatory responses at 0-30??g/ml concentration in VSMCs in vitro. 10-30??g/ml PA2 inhibited PDGF-mediated NAD(P)H oxidase activation and intracellular ROS formation in VSMCs. Furthermore, the effects exerted by PA2 involve the participation of KDR and Jak-2/STAT-3/cPLA₂ signaling pathways. These data also highlight the possible therapeutic use of PA2 in vascular proliferative diseases, where abnormal proliferation and migration play important pathological roles.

Platelet-derived growth factor BB stimulates differentiation of rat immature Leydig cells

Platelet-derived growth factor (PDGF) is one family of growth factors that regulate cell growth and differentiation. Rat Leydig cells express PDGF-β receptor (PDGFRB) during pubertal development. However, the mechanism of PDGF in the regulation of Leydig cell development is unclear. In the present study, rat immature Leydig cells were isolated from the testes of 35-day-old Sprague-Dawley rats and treated with 1 and 10 ng/mL of PDGF-BB. After 24 h of treatment, these cells were harvested for genomics profiling and the medium steroids were measured. 1 and 10 ng/mL PDGF-BB significantly increased androgen production by rat immature Leydig cells. Genomics profiling analysis showed that the expression levels of steroidogenic acute regulatory protein (Star) were increased by 2-fold. Further analysis showed that Fos expression level was increased 2- and 5-fold by 1 and 10 ng/mL PDGF-BB, respectively. In conclusion, PDGF-BB stimulated the differentiation of rat immature Leydig cells via regulating Star.

MiR-137 inhibited cell proliferation and migration of vascular smooth muscle cells via targeting IGFBP-5 and modulating the mTOR/STAT3 signaling

Abnormal proliferation of vascular smooth muscle cells (VSMCs) contributes to the development of cardiovascular diseases. Studies have shown the great impact of microRNAs (miRNAs) on the cell proliferation of VSMCs. This study examined the effects of miR-137 on the cell proliferation and migration of VSMCs and also explored the underlying molecular mechanisms. The mRNA and protein expression levels were determined by qRT-PCR and western blot assays, respectively. The CCK-8 assay, wound healing assay and transwell migration assay were performed to measure cell proliferation and migration of VSMCs. The miR-137-targeted 3’untranslated region of insulin-like growth factor-binding protein-5 (IGFBP-5) was confirmed by luciferase reporter assay. Platelet-derived growth factor-bb (PDGF-bb) treatment enhanced cell proliferation and suppressed the expression of miR-137 in VSMCs. The gain-of-function and loss-of-function assays showed that overexpression of miR-137 suppressed the cell proliferation and migration, and also inhibited the expression of matrix genes of VSMCs; down-regulation of miR-137 had the opposite effects on VSMCs. Bioinformatics analysis and luciferase report assay results showed that IGFBP-5 was a direct target of miR-137, and miR-137 overexpression suppressed the IGFBP-5 expression and down-regulation of miR-137 increased the IGFBP-5 expression in VSMCs. PDGF-bb treatment also increased the IGFBP-5 mRNA expression. In addition, enforced expression of IGFBP-5 reversed the inhibitory effects of miR-137 on cell proliferation and migration of VSMCs. More importantly, overexpression of miR-137 also suppressed the activity of mTOR/STAT3 signaling in VSMCs. Taken together, the results suggest that miR-137 may suppress cell proliferation and migration of VSMCs via targeting IGFBP-5 and modulating mTOR/STAT3 signaling pathway.

MiR-448 promotes vascular smooth muscle cell proliferation and migration in through directly targeting MEF2C

Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) is a critical process in various cardiovascular diseases such as coronary artery disease (CAD), atherosclerosis, stroke, and hypertension. MicroRNAs (miRNAs) are small, short, and noncoding RNAs that inhibit gene expression through binding to the 3'-UTR (3' untranslated regions) of target gene mRNAs. We showed that the expression of miR-448 was upregulated in VSMCs from coronary atherosclerotic plaques compared with normal coronary artery tissues. We also found that PDGF-bb promoted VSMCs proliferation and could induce miR-448 expression. Ectopic miR-448 expression induced VSMCs proliferation. Overexpression of miR-448 induced ki-67 mRNA and protein expression. Moreover, we identified MEF2C was a direct target of miR-448 in VSMCs. Overexpression of miR-448 promoted VSMCs migration. Furthermore, overexpression of MEF2C decreased miR-448-induced VSMCs proliferation and migration. These evidences suggested that miR-448 played an important role in the proliferation and migration of VSMCs.

Effect of Huaier On the Proliferation of Mesangial Cells in Anti-Thy-1 Nephritis

BACKGROUND/AIMS

To determine whether an aqueous extract of Trametes robiniophila Murr. (Huaier) suppresses anti-Thy-1 mesangial proliferative glomerulonephritis (MsPGN) in vivo and platelet-derived growth factor (PDGF)-BB-induced mesangial cell proliferation in vitro.

METHODS

Male Wistar rats were randomly categorized into 5 groups: Sham, Thy-1, and 3 Huaier-treated groups (low, medium, and high dose). Two weeks after treatment, urinary proteins were quantified and renal pathological changes were examined. MAX interactor 1 (Mxi-1) and proliferating cell nuclear antigen (PCNA) expression levels in isolated glomeruli, rat mesangial cell viability, cell-cycle distribution, and cell-cycle pathways were assessed.

RESULTS

Huaier diminished the proliferative damages and urinary protein secretion in Thy-1 rats. PCNA was downregulated, whereas Mxi-1 was upregulated in the isolated glomeruli of Huaier-treated groups compared with the Thy-1 group. Huaier inhibited PDGF-BB- stimulated proliferation of rat mesangial cells in a time- and dose-dependent manner (50% inhibitory concentration = 6.19 mg/mL) and induced G2 cell-cycle arrest. Cell-cycle pathway proteins were downregulated, whereas Mxi-1 was upregulated in Huaier-treated mesangial cells compared with PDGF-BB-stimulated cells.

CONCLUSION

Huaier reduces urinary protein excretion and relieves hyperplasia in mesangial cells in anti-Thy-1 MsPGN as well as inhibits PDGF-BB-stimulated proliferation and DNA synthesis of rat mesangial cells in vitro, suggesting its novel therapeutic potential in MsPGN.

rhPDGF-BB combined with ADSCs in the treatment of Achilles tendinitis via miR-363/PI3 K/Akt pathway

To investigate the mechanism of recombinant human platelet-derived growth factor-BB (rhPDGF-BB) and human adipose-derived stem cells (hADSCs) in the treatment of Achilles tendinitis. Biomechanical indices of stiffness, stress, and maximum load-to-failure were detected by biomechanical test. mRNA and protein levels of miR-363, p-PI3K/AKT, tendon-related genes Collagen I, Scleraxis (Scx), and Tenascin C (TNC) were measured by qRT-PCR and western blot. The proliferation of hADSCs was accessed by MTT assay. Biomechanical indices of stiffness, stress, and maximum load-to-failure, and mRNA and protein levels of tendon-related genes could be improved by rhPDGF-BB or hADSCs alone, and could be further improved by rhPDGF-BB + hADSCs. rhPDGF-BB and hADSCs downregulated the expression of miR-363 and upregulated the levels of p-PI3K/Akt, and rhPDGF-BB + hADSCs further strengthened these effects. In addition, rhPDGF-BB promoted the proliferation of hADSCs in vitro and upregulated the expression of tendon-related genes. miR-363 mimic downregulated the levels of p-PI3K/Akt, miR-363 inhibitor upregulated the levels of p-PI3K/Akt, and miR-363 mimic and PI3K/Akt pathway inhibitor LY294002 reversed the positive effect of rhPDGF-BB on the proliferation of hADSCs, which suggested that rhPDGF-BB promoted the proliferation of hADSCs via miR-363/PI3K/Akt pathway. Biomechanical indices and tendon-related genes could be improved by rhPDGF-BB and hADSCs. Moreover, rhPDGF-BB promoted the proliferation of hADSCs via miR-363/PI3K/Akt pathway, indicating that rhPDGF-BB combined with ADSCs could treat Achilles tendinitis via miR-363/PI3K/Akt pathway.

Platelet-derived growth factor BB enhances osteoclast formation and osteoclast precursor cell chemotaxis

Enhanced osteoclast formation increases bone resorption, which triggers bone remodeling. Platelet-derived growth factor BB (PDGF-BB) enhances precursor cell homing, angiogenesis, and bone healing, and thereby could also treat osteoporosis. However, the effect of PDGF-BB on osteoclast formation is not fully understood. We investigated whether exogenous recombinant PDGF-BB directly affects osteoclast formation and osteoclast precursor cell chemotaxis. The murine monocyte-macrophage cell line RAW264.7 and bone-marrow-derived macrophages were cultured with recombinant mouse PDGF-BB with or without a platelet-derived growth factor receptor β inhibitor (AG-1295) or a Janus kinase 2 inhibitor (AG-490) to analyze the effect on osteoclastogenesis in vitro. PDGF-BB with or without AG-490 or AG-1295 was locally administrated in the mandibular fracture of 16-week-old Sprague Dawley rats (n = 18) for 1-2 weeks to analyze the effect on osteoclastogenesis in vivo. The effect of the treatments on osteoclast formation, osteoclast precursor cell migration, and expression of osteoclastogenic signaling molecules was analyzed. PDGF-BB enhanced osteoclast formation both in vitro and in vivo, but AG-490 and AG-1295 inhibited this effect. PDGF-BB enhanced phosphorylation of extracellular-signal-regulated kinase 1/2 (ERK1/2), Akt, and signal transducer and activator of transcription 3 (STAT3) in RAW264.7 cells. AG-490 inhibited PDGF-BB-induced STAT3 phosphorylation. PDGF-BB enhanced RAW264.7 cell migration and gene expression of osteoclastogenic signaling molecules (i.e., nuclear factor of activated T cells 1, dendrocyte-expressed seven transmembrane protein, and B-cell lymphoma 2), and treatment with AG-1295, AG-490, or S3I-201 (a STAT3 inhibitor) reduced this effect. PDGF-BB enhanced osteoclast formation, osteoclast precursor cell chemotaxis, and phosphorylation of STAT3, Akt, and ERK1/2. but AG-1295 and AG-490 reduced this effect. These findings reflect the complexity of PDGF-BB in bone biology.

Stat6 Promotes Intestinal Tumorigenesis in a Mouse Model of Adenomatous Polyposis by Expansion of MDSCs and Inhibition of Cytotoxic CD8 Response

Intestinal tumorigenesis in the ApcMin/+ model is initiated by aberrant activation of Wnt pathway. Increased IL-4 expression in human colorectal cancer tissue and growth of colon cancer cell lines implied that IL-4–induced Stat6-mediated tumorigenic signaling likely contributes to intestinal tumor progression in ApcMin/+ mice. Stat6 also appears to promote expansion of myeloid-derived suppressor cells (MDSCs) cells. MDSCs promote polyp formation in the ApcMin/+ model. Hence, Stat6 could have a broad role in coordinating both polyp cell proliferation and MDSC expansion. We found that IL-4–induced Stat6-mediated proliferation of intestinal epithelial cells is augmented by platelet-derived growth factor–BB, a tumor-promoting growth factor. To determine whether polyp progression in ApcMin/+ mice is dependent on Stat6 signaling, we disrupted Stat6 in this model. Total polyps in the small intestine were fewer in ApcMin/+ mice lacking Stat6. Furthermore, proliferation of polyp epithelial cells was reduced, indicating that Stat6 in part controlled polyp formation. Stat6 also promoted expansion of MDSCs in the spleen and lamina propria of ApcMin/+ mice, implying regulation of antitumor T-cell response. More CD8 cells and reduced PD-1 expression on CD4 cells correlated with reduced polyps. In addition, a strong CD8-mediated cytotoxic response led to killing of tumor cells in Stat6-deficient ApcMin/+ mice. Therefore, these findings show that Stat6 has an oncogenic role in intestinal tumorigenesis by promoting polyp cell proliferation and immunosuppressive mediators, and preventing an active cytotoxic process.

Induced differentiation of human gingival fibroblasts into VSMC-like cells

Vascular smooth muscle cells (VSMCs) are major component of the vascular wall, and they play an essential role in maintaining the basic physiological function and stable structure of the vascular wall. In the present study, human gingival fibroblasts (HGFs) were cultured and induced into VSMC-like cells in vitro to confirm that HGFs with properties of stem cells have the potential for differentiation. The epithelium isolated from patients was extracted from normal human gingiva consisting of epithelium and connective tissue. HGFs were first identified by morphological examination, as well as specific gene and protein expression, and then induced by 10ng/mL PDGF-BB combined with 2ng/mL of TGF-β1 for 28 days. After induction, ICS data indicated that induced VSMC-like cells were positive for α-SMA and SM-MHC, and IFA data showed that induced cells were positive for SM22α and Cnn1. RT-PCR results demonstrated that α-SMA and SM-MHC mRNA were specifically expressed, and myofilament-like structures also appeared in induced cells. In conclusion, the data indicated that HGFs could differentiate to VSMC-like cells with typical VSMC morphologic, ultrastructural, and immunological characteristics via induction with PDGF-BB and TGF-β1.

Dual role of pericyte α6β1-integrin in tumour blood vessels

The α6β1-integrin is a major laminin receptor, and formation of a laminin-rich basement membrane is a key feature in tumour blood vessel stabilisation and pericyte recruitment, processes that are important in the growth and maturation of tumour blood vessels. However, the role of pericyte α6β1-integrin in angiogenesis is largely unknown. We developed mice where the α6-integrin subunit is deleted in pericytes and examined tumour angiogenesis and growth. These mice had: (1) reduced pericyte coverage of tumour blood vessels; (2) reduced tumour blood vessel stability; (3) increased blood vessel diameter; (4) enhanced blood vessel leakiness, and (5) abnormal blood vessel basement membrane architecture. Surprisingly, tumour growth, blood vessel density and metastasis were not altered. Analysis of retinas revealed that deletion of pericyte α6-integrin did not affect physiological angiogenesis. At the molecular level, we provide evidence that pericyte α6-integrin controls PDGFRβ expression and AKT-mTOR signalling. Taken together, we show that pericyte α6β1-integrin regulates tumour blood vessels by both controlling PDGFRβ and basement membrane architecture. These data establish a novel dual role for pericyte α6-integrin as modulating the blood vessel phenotype during pathological angiogenesis.

The platelet-derived growth factor receptor/STAT3 signaling pathway regulates the phenotypic transition of corpus cavernosum smooth muscle in rats

Erectile dysfunction (ED) is a common clinical disease that is difficult to treat. We previously found that hypoxia modulates the phenotype of primary corpus cavernosum smooth muscle cells (CCSMCs) in rats, but the underlying molecular mechanism is still unknown. Platelet-derived growth factor receptor (PDGFR)-related signaling pathways are correlated with cell phenotypic transition, but research has been focused more on vascular smooth muscle and tracheal smooth muscle and less on CCSMCs. Here, we investigated the role of PDGFR-related signaling pathways in penile CCSMCs, which were successfully isolated from rats and cultured in vitro. PDGF-BB at 5, 10, or 20 ng/ml altered CCSMC morphology from the original elongated, spindle shape to a broader shape and promoted the synthetic phenotype and expression of the related proteins vimentin and collagen-I, while inhibiting the contractile phenotype and expression of the related proteins smooth muscle (SM) α-actin (α-SMA) and desmin. Inhibition of PDGFR activity via siRNA or the PDGFR inhibitor crenolanib inhibited vimentin and collagen-I expression, increased α-SMA and desmin expression, and considerably inhibited serine-threonine protein kinase (AKT) and signal transducer and activator of transcription 3 (STAT3) phosphorylation. STAT3 knockdown promoted the contractile phenotype, inhibited vimentin and collagen-I expression, and increased α-SMA and desmin expression, whereas AKT knockdown did not affect phenotype-associated proteins. STAT3 overexpression in CCSMC cells weakened the suppressive effect of PDGFR inhibition on the morphology and phenotypic transformation induced by PDGF-BB. Through activation of the PDGFR/STAT3 signaling pathway, PDGF promoted the synthetic phenotype transition; thus, regulation of this pathway might contribute to ED therapy.

Biological characteristics of embryonic epicardial cells in vitro correlate with embryonic day

The epicardial cell (EpiC) culture system plays an important role in investigating the specific mechanisms and signaling molecules that are involved in the development of EpiCs. From this early formation until adulthood, EpiCs undergo dynamic changes in the expression of embryonic genes that correlate with changes in the embryonic EpiC properties. The differences of embryonic EpiC properties may affect the related results of experiments in which EpiC culture system is used; however, these differences have not been explored. Therefore, in this study we examined the differences in the biological characteristics of EpiCs on different embryonic days in vitro EpiCs were isolated from embryonic ventricle explants on embryonic day (E) 11.5, E13.5, and E15.5. The differences in the migration, proliferation and differentiation were studied in EpiCs of different embryonic day by scratch assay, cell cycle analysis and platelet derived growth factor-bb (PDGF-BB) treatment. The results showed that EpiCs were successfully cultured from E11.5, E13.5, and E15.5 embryonic ventricle explants. The time windows of E11.5, E13.5, and E15.5 EpiC isolation out of the explants were different. The migration abilities of E11.5, E13.5, and E15.5 EpiCs decreased during embryonic development. Smooth muscle cell differentiation potential of early stage EpiCs was better than that of the later stage EpiCs. Although the proliferation ability of E11.5 EpiCs was significantly weaker than those of E13.5 and E15.5 EpiCs, the proliferation abilities of E13.5 and E15.5 EpiCs did not differ. These results suggest that the biological characteristics of EpiCs correlate with the timing of embryonic development, and different embryonic stage of ventricle should be properly chosen for culturing EpiCs depending on the purposes of the specific experiments.

Tyrosine Kinase Inhibitors Regulate OPG through Inhibition of PDGFRβ

Nilotinib and imatinib are tyrosine kinase inhibitors (TKIs) used in the treatment of chronic myeloid leukemia (CML) and gastrointestinal stromal tumors (GIST). In vitro, imatinib and nilotinib inhibit osteoclastogenesis, and in patients they reduce levels of bone resorption. One of the mechanisms that might underlie these effects is an increase in the production of osteoprotegerin (OPG). In the current work we report that platelet-derived growth factor receptor beta (PDGFRβ) signaling regulates OPG production in vitro. In addition, we have shown that TKIs have effects on RANKL signaling through inhibition of the PDGFRβ and other target receptors. These findings have implications for our understanding of the mechanisms by which TKIs affect osteoclastogenesis, and the role of PDGFRβ signaling in regulating osteoclastogenesis. Further studies are indicated to confirm the clinical effects of PDGFRβ-inhibitors and to elaborate the intracellular pathways that underpin these effects.

Syndecan-4 enhances PDGF-BB activity in diabetic wound healing

Non-healing ulcers are a common consequence of long-term diabetes and severe peripheral vascular disease. These non-healing wounds are a major source of morbidity in patients with diabetes and place a heavy financial burden on the healthcare system. Growth factor therapies are an attractive strategy for enhancing wound closure in non-healing wounds but have only achieved mixed results in clinical trials. Platelet derived growth factor-BB (PDGF-BB) is the only currently approved growth factor therapy for non-healing wounds. However, PDGF-BB therapy is not effective in many patients and requires high doses that increase the potential for side effects. In this work, we demonstrate that syndecan-4 delivered in a proteoliposomal formulation enhances PDGF-BB activity in diabetic wound healing. In particular, syndecan-4 proteoliposomes enhance the migration of keratinocytes derived from patients with diabetes. In addition, syndecan-4 proteoliposomes sensitize keratinocytes to PDGF-BB stimulation, enhancing the intracellular signaling response to PDGF-BB. We further demonstrated that co-therapy with syndecan-4 proteoliposomes enhanced wound closure in diabetic, hyperlipidemic ob/ob mice. Wounds treated with both syndecan-4 proteoliposomes and PDGF-BB had increased re-epithelization and angiogenesis in comparison to wounds treated with PDGF-BB alone. Moreover, the wounds treated with syndecan-4 proteoliposomes and PDGF-BB also had increased M2 macrophages and reduced M1 macrophages, suggesting syndecan-4 delivery induces immunomodulation within the healing wounds. Together our findings support that syndecan-4 proteoliposomes markedly improve PDGF-BB efficacy for wound healing and may be useful in enhancing treatments for non-healing wounds.

STATEMENT OF SIGNIFICANCE

Non-healing wounds are major healthcare issue for patients with diabetes and peripheral vascular disease. Growth factor therapies have potential for healing chronic wounds but have not been effective for many patients. PDGF-BB is currently the only approved growth factor for enhancing wound healing. However, it has not seen widespread adoption due to limited efficacy and high cost. In this work, we have developed an enhancing agent that improves the activity of PDGF-BB in promoting wound healing in animals with diabetes. This co-therapy may be useful in improving the efficacy of PDGFBB and enhance its safety through lowering the dose of growth factor needed to improve wound healing.

Heparinized collagen sutures for sustained delivery of PDGF-BB: Delivery profile and effects on tendon-derived cells In-Vitro

Suturing is the standard of repair for lacerated flexor tendons. Past studies focused on delivering growth factors to the repair site by incorporating growth factors to nylon sutures which are commonly used in the repair procedure. However, conjugation of growth factors to nylon or other synthetic sutures is not straightforward. Collagen holds promise as a suture material by way of providing chemical sites for conjugation of growth factors. On the other hand, collagen also needs to be reconstituted as a mechanically robust thread that can be sutured. In this study, we reconstituted collagen solutions as suturable collagen threads by using linear electrochemical compaction. Prolonged release of PDGF-BB (Platelet derived growth factor-BB) was achieved by covalent bonding of heparin to the collagen sutures. Tensile mechanical tests of collagen sutures before and after chemical modification indicated that the strength of sutures following chemical conjugation stages was not compromised. Strength of lacerated tendons sutured with epitendinous collagen sutures (11.2±0.7N) converged to that of the standard nylon suture (14.9±2.9N). Heparin conjugation of collagen sutures didn't affect viability and proliferation of tendon-derived cells and prolonged the PDGF-BB release up to 15days. Proliferation of cells seeded on PDGF-BB incorporated collagen sutures was about 50% greater than those seeded on plain collagen sutures. Collagen that is released to the media by the cells increased by 120% under the effects of PDGF-BB and collagen production by cells was detectable by histology as of day 21. Addition of PDGF-BB to collagen sutures resulted in a moderate decline in the expression of the tendon-associated markers scleraxis, collagen I, tenomodulin, and COMP; however, expression levels were still greater than the cells seeded on collagen gel. The data indicate that the effects of PDGF-BB on tendon-derived cells mainly occur through increased cell proliferation and that longer term studies are needed to confirm whether this proliferation is outweighs the moderate reduction in the expression of tendon-associated genes.

STATEMENT OF SIGNIFICANCE

A mechanically robust pure collagen suture was fabricated via linear electrocompaction and conjugated with heparin for prolonged delivery of PDFG-BB. Sustained delivery of the PDGF-BB improved the proliferation of tendon derived cells substantially at the expense of a moderate downregulation of tenogenic markers. The collagen threads were functionally applicable as epitendinous sutures when applied to chicken flexor tendons in vitro. Overall, electrocompacted collagen sutures holds potential to improve repair outcome in flexor tendon surgeries by improving cellularity and collagen production through delivery of the PDGF-BB. The bioinductive suture concept can be applied to deliver other growth factors for a wide-array of applications.

Platelet-Derived Growth Factor-BB Protects Mesenchymal Stem Cells (MSCs) Derived From Immune Thrombocytopenia Patients Against Apoptosis and Senescence and Maintains MSC-Mediated Immunosuppression

: Immune thrombocytopenia (ITP) is characterized by platelet destruction and megakaryocyte dysfunction. Mesenchymal stem cells (MSCs) from ITP patients (MSC-ITP) do not exhibit conventional proliferative abilities and thus exhibit defects in immunoregulation, suggesting that MSC impairment might be a mechanism involved in ITP. Platelet-derived growth factor (PDGF) improves growth and survival in various cell types. Moreover, PDGF promotes MSC proliferation. The aim of the present study was to analyze the effects of PDGF-BB on MSC-ITP. We showed that MSC-ITP expanded more slowly and appeared flattened and larger. MSC-ITP exhibited increased apoptosis and senescence compared with controls. Both the intrinsic and extrinsic pathways account for the enhanced apoptosis. P53 and p21 expression were upregulated in MSC-ITP, but inhibition of p53 with pifithrin-α markedly inhibited apoptosis and senescence. Furthermore, MSCs from ITP patients showed a lower capacity for inhibiting the proliferation of activated T cells inducing regulatory T cells (Tregs) and suppressing the synthesis of anti-glycoprotein (GP)IIb-IIIa antibodies. PDGF-BB treatment significantly decreased the expression of p53 and p21 and increased survivin expression in MSC-ITP. In addition, the apoptotic rate and number of senescent cells in ITP MSCs were reduced. Their impaired ability for inhibiting activated T cells, inducing Tregs, and suppressing the synthesis of anti-GPIIb-IIIa antibodies was restored after PDGF-BB treatment. In conclusion, we have demonstrated that PDGF-BB protects MSCs derived from ITP patients against apoptosis, senescence, and immunomodulatory defects. This protective effect of PDGF-BB is likely mediated via the p53/p21 pathway, thus potentially providing a new therapeutic approach for ITP.

SIGNIFICANCE

Immune thrombocytopenia (ITP) is characterized by platelet destruction and megakaryocyte dysfunction. Platelet-derived growth factor (PDGF) improves growth and survival in various cell types and promotes mesenchymal stem cell (MSC) proliferation. PDGF-BB protects MSCs derived from ITP patients against apoptosis, senescence, and immunomodulatory defects. This protective effect of PDGF-BB is likely mediated via the p53/p21 pathway, thus potentially providing a new therapeutic approach for ITP.

Differentiation of Murine Bone Marrow-Derived Smooth Muscle Progenitor Cells Is Regulated by PDGF-BB and Collagen

Smooth muscle cells (SMCs) are key regulators of vascular disease and circulating smooth muscle progenitor cells may play important roles in vascular repair or remodelling. We developed enhanced protocols to derive smooth muscle progenitors from murine bone marrow and tested whether factors that are increased in atherosclerotic plaques, namely platelet-derived growth factor-BB (PDGF-BB) and monomeric collagen, can influence the smooth muscle specific differentiation, proliferation, and survival of mouse bone marrow-derived progenitor cells. During a 21 day period of culture, bone marrow cells underwent a marked increase in expression of the SMC markers α-SMA (1.93 ± 0.15 vs. 0.0008 ± 0.0003 (ng/ng GAPDH) at 0 d), SM22-α (1.50 ± 0.27 vs. 0.005 ± 0.001 (ng/ng GAPDH) at 0 d) and SM-MHC (0.017 ± 0.004 vs. 0.001 ± 0.001 (ng/ng GAPDH) at 0 d). Bromodeoxyuridine (BrdU) incorporation experiments showed that in early culture, the smooth muscle progenitor subpopulation could be identified by high proliferative rates prior to the expression of smooth muscle specific markers. Culture of fresh bone marrow or smooth muscle progenitor cells with PDGF-BB suppressed the expression of α-SMA and SM22-α, in a rapidly reversible manner requiring PDGF receptor kinase activity. Progenitors cultured on polymerized collagen gels demonstrated expression of SMC markers, rates of proliferation and apoptosis similar to that of cells on tissue culture plastic; in contrast, cells grown on monomeric collagen gels displayed lower SMC marker expression, lower growth rates (319 ± 36 vs. 635 ± 97 cells/mm2), and increased apoptosis (5.3 ± 1.6% vs. 1.0 ± 0.5% (Annexin 5 staining)). Our data shows that the differentiation and survival of smooth muscle progenitors are critically affected by PDGF-BB and as well as the substrate collagen structure.

Intrinsic Deregulation of Vascular Smooth Muscle and Myofibroblast Differentiation in Mesenchymal Stromal Cells from Patients with Systemic Sclerosis

Introduction

Obliterative vasculopathy and fibrosis are hallmarks of systemic sclerosis (SSc), a severe systemic autoimmune disease. Bone marrow-derived mesenchymal stromal cells (MSCs) from SSc patients may harbor disease-specific abnormalities. We hypothesized disturbed vascular smooth muscle cell (VSMC) differentiation with increased propensity towards myofibroblast differentiation in response to SSc-microenvironment defining growth factors and determined responsible mechanisms.

Methods

We studied responses of multipotent MSCs from SSc-patients (SSc-MSCs) and healthy controls (H-MSCs) to long-term exposure to CTGF, b-FGF, PDGF-BB or TGF-β1. Differentiation towards VSMC and myofibroblast lineages was analyzed on phenotypic, biochemical, and functional levels. Intracellular signaling studies included analysis of TGF-β receptor regulation, SMAD, AKT, ERK1/2 and autocrine loops.

Results

VSMC differentiation towards both, contractile and synthetic VSMC phenotypes in response to CTGF and b-FGF was disturbed in SSc-MSCs. H-MSCs and SSc-MSCs responded equally to PDGF-BB with prototypic fibroblastic differentiation. TGF-β1 initiated myofibroblast differentiation in both cell types, yet with striking phenotypic and functional differences: In relation to H-MSC-derived myofibroblasts induced by TGF-β1, those obtained from SSc-MSCs expressed more contractile proteins, migrated towards TGF-β1, had low proliferative capacity, and secreted higher amounts of collagen paralleled by reduced MMP expression. Higher levels of TGF-β receptor 1 and enhanced canonical and noncanonical TGF-β signaling in SSc-MSCs accompanied aberrant differentiation response of SSc-MSCs in comparison to H-MSCs.

Conclusions

Deregulated VSMC differentiation with a shift towards myofibroblast differentiation expands the concept of disturbed endogenous regenerative capacity of MSCs from SSc patients. Disease related intrinsic hyperresponsiveness to TGF-β1 with increased collagen production may represent one responsible mechanism. Better understanding of repair barriers and harnessing beneficial differentiation processes in MSCs could widen options of autologous MSC application in SSc patients.

Gentiana lutea exerts anti-atherosclerotic effects by preventing endothelial inflammation and smooth muscle cell migration

BACKGROUND AND AIMS

Studies suggest that Gentiana lutea (GL), and its component isovitexin, may exhibit anti-atherosclerotic properties. In this study we sought to investigate the protective mechanism of GL aqueous root extract and isovitexin on endothelial inflammation, smooth muscle cell migation, and on the onset and progression of atherosclerosis in streptozotocin (STZ)-induced diabetic rats.

METHODS AND RESULTS

Our results show that both GL extract and isovitexin, block leukocyte adhesion and generation of reactive oxygen species in human umbilical vein endothelial cells (HUVECs) and rat aortic smooth muscle cells (RASMCs), following TNF-alpha and platelet derived growth factor-BB (PDGF-BB) challenges respectively. Both the extract and isovitexin blocked TNF-α induced expression of ICAM-1 and VCAM-1 in HUVECs. PDGF-BB induced migration of RASMCs and phospholipase C-γ activation, were also abrogated by GL extract and isovitexin. Fura-2 based ratiometric measurements demonstrated that, both the extact, and isovitexin, inhibit PDGF-BB mediated intracellular calcium rise in RASMCs. Supplementation of regular diet with 2% GL root powder for STZ rats, reduced total cholesterol in blood. Oil Red O staining demonstrated decreased lipid accumulation in aortic wall of diabetic animals upon treatment with GL. Medial thickness and deposition of collagen in the aortic segment of diabetic rats were also reduced upon supplementation. Immunohistochemistry demonstrated reduced expression of vascular cell adhesion molecule-1 (VCAM-1), inducible nitric oxide synthase (iNOS), and vascular endothelial cadherin (VE-cadherin) in aortic segments of diabetic rats following GL treatment.

CONCLUSIONS

Thus, our results support that GL root extract/powder and isovitexin exhibit anti-atherosclerotic activities.

Epigenetic factors MeCP2 and HDAC6 control α-tubulin acetylation in cardiac fibroblast proliferation and fibrosis

AIM AND OBJECTIVE

Cardiac fibrosis is an important pathological feature of cardiac remodeling in heart diseases. Methyl-CpG-binding protein 2 (MeCP2) is a transcription inhibitor, and plays a key role in the fibrotic diseases. However, the precise role of MeCP2 in cardiac fibrosis remains unclear. α-tubulin plays an essential role in cell function, whereby the acetylation state of α-Tubulin dictates the efficiency of cell proliferation and differentiation. This study was undertaken to investigate that MeCP2 dynamics affect the acetylation state of α-tubulin in the cardiac fibrosis.

METHODS

Forty adult male Sprague-Dawley (SD) rats were randomly divided into two groups, cardiac fibrosis was produced by common ISO. Cardiac fibroblasts (CFs) were harvested from SD neonate rats and cultured. The expression of HDAC6, MeCP2, α-SMA, collagen I was measured by western blotting and qRT-PCR. siRNA of HDAC6 and MeCP2 effect the proliferation of cardiac fibroblasts, and affect the acetylation state of α-tubulin.

RESULTS

We have found the acetylation state of α-tubulin in cardiac fibroblasts as well as cardiac tissue from a ISO-induced rat cardiac fibrosis model and observed a reduction in acetylated α-tubulin and an increase in the α-tubulin-specific deacetylase, histone deacetylase 6 (HDAC6). Furthermore, we have shown that treatment of cardiac fibroblasts with HDAC6 inhibitor Tubastatin A and HDAC6-siRNA can restore α-tubulin acetylation levels. In addition, treatment of cardiac fibroblasts with MeCP2-siRNA blocked cell proliferation. Knockdown of MeCP2 suppresses HDAC6 expression in activated cardiac fibroblasts but increases the acetylation of α-tubulin.

CONCLUSIONS

We demonstrated that MeCP2 may negatively control the acetylation of α-tubulin through HDAC6 in cardiac fibroblast proliferation and fibrosis. This study indicated that MeCP2 could be a potentially new therapeutic option for cardiac fibrosis.

Synergistic interaction of platelet derived growth factor (PDGF) with the surface of PLLA/Col/HA and PLLA/HA scaffolds produces rapid osteogenic differentiation

Scaffolds with structural features similar to the extracellular matrix stimulate rapid osteogenic differentiation in favorable microenvironment and with growth factor supplementation. In this study, the osteogenic potential of electrospun poly-l-lactide/hydroxyapatite/collagen (PLLA/Col/HA, PLLA/HA and PLLA/Col) scaffolds were tested in vitro with the supplementation of platelet derived growth factor-BB (PDGF-BB). Cell attachment and topography, mineralization, extracellular matrix protein localization, and gene expression of the human mesenchymal stromal cells were compared between the fibrous scaffolds PLLA/Col/HA, PLLA/Col, and PLLA/HA. The levels of osteocalcin, calcium, and mineralization were significantly greater in the PLLA/Col/HA and PLLA/HA compared with PLLA/Col. High expression of fibronectin, intracellular adhesion molecule, cadherin, and collagen 1 (Col1) suggests that PLLA/Col/HA and PLLA/HA scaffolds had superior osteoinductivity than PLLA/Col. Additionally, osteopontin, osteocalcin, osterix, Runt-related transcription factor 2 (Runx2), and bone morphogenic protein (BMP2) expression were higher in PLLA/Col/HA and PLLA/HA compared with PLLA/Col. In comparison with PLLA/Col, the PLLA/Col/HA and PLLA/HA scaffolds presented a significant upregulation of the genes Runx2, Col 1, Integrin, osteonectin (ON), bone gamma-carboxyglutamic acid-containing protein (BGALP), osteopontin (OPN), and BMP2. The upregulation of these genes was further increased with PDGF-BB supplementation. These results show that PDGF-BB acts synergistically with PLLA/Col/HA and PLLA/HA to enhance the osteogenic differentiation potential. Therefore, this combination can be used for the rapid expansion of bone marrow stromal cells into bone-forming cells for tissue engineering.

[Tricaicium phosphate complex pre-loaded with bone morphogenetic protein-2 or platelet derived growth factor-BB for repairing critical-size cranial defects in SD rats]

OBJECTIVE

To observe the effect of a new biomaterial in promoting the bone regeneration for repairing critical-size cranial defects in SD rats.

METHODS

Critical-size cranial defects were induced in 3-month-old male Sprague-Dawley rats and repaired with the implants of calcium phosphate from growth factor enhanced matrix 21 (CaPfromGEM21, control), CaPfromGEM21 preloaded with 10 ng bone morphogenetic protein-2 (BMP-2), CaPfromGEM21 preloaded with 100 ng BMP-2, CaPfromGEM21 preloaded with 0.3 µg platelet-derived growth factor-BB (PDGF-BB), or CaPfromGEM21 preloaded with 3 µg PDGF-BB. The defects were examined 6 weeks after the surgery with X-ray, micro-CT, HE staining and quantitative assessments.

RESULTS

X-ray showed defect repair in all the groups. The fracture line became obscure, and the defects were almost fully repaired by the regenerated bone tissues in PDGF-BB group. Micro-CT demonstarted new bone formation in the defects. The new bone volume was significantly greater in PDGF-BB groups than in BMP-2 groups (P<0.05). HE staining revealed the presence of new bones in the defects and new vessels in and around the new bones without inflammatory cells. The new bone area fraction was significantly greater in 10 ng BMP-2 group and 0.3 µg PDGF-BB group than in the control group (P<0.05), and the new vessel density was similar in the all the 4 cytokine-preloaded groups and all significantly greater than that in the blank and CaPfromGEM21 control group (P<0.05).

CONCLUSION

CaPfromGem21 combined with BMP-2 or PDGF-BB has good biocompatibility and can better promote bone regeneration for repairing bone defects.

MicroRNA-9 regulates cardiac fibrosis by targeting PDGFR-β in rats

The proliferation of cardiac fibroblasts (CFs) and excessive deposition of extracellular matrix (ECM) are the main pathological characteristics of cardiac fibrosis. In recent years, microRNAs (miRNAs) have been found to be a new kind of regulator in cardiac fibrosis. The purpose of this study was to investigate the role of microRNA-9 (miR-9) in the process of cardiac fibrosis and its mechanism. Treatment of cultured neonatal rat CFs with PDGF-BB or serum suppressed the expression of miR-9. Overexpression of miR-9 obviously inhibited neonatal rat CFs proliferation and collagen production as detected by MTT assays, qRT-PCR, and western blotting. The effects of miR-9 in CFs were abrogated by co-transfection with miR-9 inhibitors. Overexpression of miR-9 reduced the mRNA and protein levels of PDGFR-βand its downstream protein, extracellular signal-regulated kinase (ERK) 1/2. Silencing PDGFR-βby small interfering RNA mimicked the anti-fibrotic action of miR-9, whereas overexpression of PGDFR-β canceled the effect of miR-9 in cultured CFs. Dual-luciferase reporter assays showed that PDGFR-βwas a direct target of miR-9. Overexpression of miR-9 inhibited cardiac fibrosis by targeting PDGFR-β, indicating that miR-9 might play a role in the treatment of cardiac fibrosis.

Soluble epoxide hydrolase is involved in the development of atherosclerosis and arterial neointima formation by regulating smooth muscle cell migration

Epoxyeicosatrienoic acids (EETs) have beneficial effects on cardiovascular disease. Soluble epoxide hydrolase (sEH) metabolizes EETs to less active diols, thus diminishing their biological activity. sEH inhibitors can suppress the progression of atherosclerotic lesions in animal models. However, the regulation of sEH in vascular smooth muscle cells (VSMCs) and role of sEH in patients with atherosclerosis have not been evaluated. We hypothesize that sEH in VSMCs plays a pivotal role in atherosclerosis and injury-induced neointima formation. In this study, sEH expression in human autopsy atherosclerotic plaque was determined by immunohistochemistry. In cultured rat and human VSMCs, the phenotypic switching marker and sEH expression induced by platelet-derived growth factor-BB (PDGF-BB) were examined by Western blot analysis. Carotid-artery balloon injury was performed after adenovirus-mediated overexpression of sEH or oral administration of a potent sEH inhibitor in Sprague-Dawley rats. sEH was highly expressed in VSMCs of the intima and media within human atherosclerotic plaque. In vitro, PDGF-BB upregulated the expression in VSMCs after transcription and promoted cell proliferation and migration; the latter effect could be largely attenuated by an sEH inhibitor. Adenovirus-mediated overexpression of sEH could mimic the effect of PDGF-BB and induce VSMC proliferation and migration. In vivo, the sEH inhibitor led to a significant decrease in injury-induced neointima formation in a rat carotid-artery injury model. These data establish the effect of sEH expression on atherosclerotic progression and vascular remodeling after injury, thus identifying a novel integrative role for sEH in VSMC phenotypic modulation and migration. Blocking sEH activity may be a potential therapeutic approach for ameliorating vascular occlusive disease.

Evodiamine Attenuates PDGF-BB-Induced Migration of Rat Vascular Smooth Muscle Cells through Activating PPARγ

The uncontrolled migration of vascular smooth muscle cells (VSMCs) into the intima is a critical process in the development of atherosclerosis. Evodiamine, an indole alkaloid extracted from the Chinese medicine evodia, has been shown to inhibit tumor cell invasion and protect the cardiovascular system, but its effects on VSMCs remain unknown. In the present study, we investigated the inhibitory effects of evodiamine on the platelet-derived growth factor-BB (PDGF-BB)-induced VSMC migration using wound healing and transwell assays, and assessed its role in decreasing the protein levels of matrix metalloproteinases and cell adhesion molecules. More importantly, we found that evodiamine activated the expression and nuclear translocation of peroxisome proliferator-activated receptor γ (PPARγ). Inhibition of PPARγ activity by using its antagonist T0070907 and its specific siRNA oligonucleotides significantly attenuated the inhibitory effects of evodiamine on VSMC migration. Taken together, our results indicate a promising anti-atherogenic effect of evodiamine through attenuation of VSMC migration by activating PPARγ.

Promoting Diabetic Wound Therapy Using Biodegradable rhPDGF-Loaded Nanofibrous Membranes: CONSORT-Compliant Article

The nanofibrous biodegradable drug-loaded membranes that sustainably released recombinant human platelet-derived growth factor (rhPDGF-BB) to repair diabetic wounds were developed in this work.rhPDGF-BB and poly(lactic-co-glycolic acid) (PLGA) were mixed in hexafluoroisopropyl alcohol, followed by the electrospinning of the solutions into biodegradable membranes to equip the nanofibrous membranes. An elution technique and an enzyme-linked immunosorbent assay kit were used to determine the rhPDGF-BB release rates in vitro and in vivo from this membrane. Eighteen Sprague-Dawley streptozotocin-induced diabetic rats were randomized into 3 groups: rhPDGF-BB-loaded nanofibrous membrane group, PLGA only membrane group, and conventional gauze sponge group for the wound associated with diabetes of rat in each group.The nanofibrous biodegradable membranes released effective concentrations of rhPDGF-BB for over 21 days. The nanofibrous rhPDGF-BB-loaded PLGA membranes contained more water and were further hydrophilic than PLGA only fibers. The rhPDGF-BB-loaded PLGA membranes considerably helped the diabetic wounds repairing. Furthermore, the proliferative cells and angiogenesis of rats associated with diabetes by rhPDGF-BB-loaded nanofibrous membranes were greater than those of other groups, owing to the increased matrix metalloproteinase 9.These biodegradable rhPDGF-BB-loaded membranes were effective in treating diabetic wounds as very advanced accelerators during the initial phases of wound-healing process.

[Platelet-derived growth factor-BB induces phenotypic transformation of corpus cavernosum smooth muscle cells in SD rats]

OBJECTIVE

To evaluate the effect of the platelet-derived growth factor-BB (PDGF-BB) on the phenotypic transformation of corpus cavernosum smooth muscle cells (CCSMC) in SD rats.

METHODS

CCSMCs were primarily cultured in the modified tissue sticking medium and subjected to immunofluorescence assay. The cells were divided into a blank control and four PDGF-BB groups, the latter exposed to 5, 10, 20, and 40 ng/ml of PDGF-BB, respectively, for 24 hours, and the cells in the 20 ng/ml PDGF-BB group treated for 24, 48, and 72 hours. The the relative expressions of α-SMA, SMMHC, calponin, and OPN mRNA were determined by real-time fluorescence quantitative RT-PCR (qRT-PCR).

RESULTS

The α-SMA positive rate of the CCSMCs was over 95%. Compared with the blank control group, the expression levels of α-SMA, SMMHC, and calponin mRNA were significantly decreased (P < 0.05) while that of OPN mRNA remarkably increased (P < 0.05) in the PDGF-BB groups. The 20 ng/ml PDGF-BB group also showed significantly downregulated expressions of α-SMA, SMMHC, and calponin mRNA (P < 0.05) and upregulated expression of OPN mRNA (P < 0.05) at 24, 48, and 72 hours.

CONCLUSION

PDGF-BB can induce the transformation of the phenotype of CCSMCs in SD rats from the contractile to the synthetic type.

Atorvastatin calcium inhibits phenotypic modulation of PDGF-BB-induced VSMCs via down-regulation the Akt signaling pathway

Plasticity of vascular smooth muscle cells (VSMCs) plays a central role in the onset and progression of proliferative vascular diseases. In adult tissue, VSMCs exist in a physiological contractile-quiescent phenotype, which is defined by lack of the ability of proliferation and migration, while high expression of contractile marker proteins. After injury to the vessel, VSMC shifts from a contractile phenotype to a pathological synthetic phenotype, associated with increased proliferation, migration and matrix secretion. It has been demonstrated that PDGF-BB is a critical mediator of VSMCs phenotypic switch. Atorvastatin calcium, a selective inhibitor of 3-hydroxy-3-methyl-glutaryl l coenzyme A (HMG-CoA) reductase, exhibits various protective effects against VSMCs. In this study, we investigated the effects of atorvastatin calcium on phenotype modulation of PDGF-BB-induced VSMCs and the related intracellular signal transduction pathways. Treatment of VSMCs with atorvastatin calcium showed dose-dependent inhibition of PDGF-BB-induced proliferation. Atorvastatin calcium co-treatment inhibited the phenotype modulation and cytoskeleton rearrangements and improved the expression of contractile phenotype marker proteins such as α-SM actin, SM22α and calponin in comparison with PDGF-BB alone stimulated VSMCs. Although Akt phosphorylation was strongly elicited by PDGF-BB, Akt activation was attenuated when PDGF-BB was co-administrated with atorvastatin calcium. In conclusion, atorvastatin calcium inhibits phenotype modulation of PDGF-BB-induced VSMCs and activation of the Akt signaling pathway, indicating that Akt might play a vital role in the modulation of phenotype.

Optimizing culture medium composition to improve oligodendrocyte progenitor cell yields in vitro from subventricular zone-derived neural progenitor cell neurospheres

Neural Stem and Progenitor Cells (NSC/NPC) are gathering tangible recognition for their uses in cell therapy and cell replacement therapies for human disease, as well as a model system to continue research on overall neural developmental processes in vitro. The Subventricular Zone is one of the largest NSC/NPC niches in the developing mammalian Central Nervous System, and persists through to adulthood. Oligodendrocyte progenitor cell (OPC) enriched cultures are usefull tools for in vitro studies as well as for cell replacement therapies for treating demyelination diseases. We used Subventricular Zone-derived NSC/NPC primary cultures from newborn mice and compared the effects of different growth factor combinations on cell proliferation and OPC yield. The Platelet Derived Growth Factor-AA and BB homodimers had a positive and significant impact on OPC generation. Furthermore, heparin addition to the culture media contributed to further increase overall culture yields. The OPC generated by this protocol were able to mature into Myelin Basic Protein-expressing cells and to interact with neurons in an in vitro co-culture system. As a whole, we describe an optimized in vitro method for increasing OPC.

PDGF-D signaling in portal myofibroblasts and hepatic stellate cells proves identical to PDGF-B via both PDGF receptor type α and β

Platelet-derived growth factor-D (PDGF-D) is one member of PDGF growth factors and known to signal by binding to and activating its cognate receptor type β (PDGFR-β). Beside PDGF-B, PDGF-D is a potent growth factor for stellate cell growth and proliferation and therefore potentiates the extracellular matrix deposition in liver fibrogenesis. We aimed to explore the signaling and molecular mechanisms of PDGF-D in liver fibrogenesis using the primary liver portal myofibroblasts and hepatic stellate cells. Unexpectedly we found PDGF-D to bind to PDGFR-α, thus inducing receptor endocytosis and decreasing the amount of PDGFR-α significantly. PDGF-D activates PDGFR-α specific tyrosine 754 and -1018 phosphorylation and CrkII, the adaptor protein that is specifically recruited by activated PDGFR-α. As a novel finding we could also demonstrate that recombinant PDGFR-α-Fc chimera homodimer is able to bind PDGF-D and thus prevent PDGF-D signaling. PDGF-D does induce individual PDGFR-β specific tyrosine phosphorylation similar to the PDGF-B. Additionally, PDGF-D enhances extracellular matrix accumulation comparable to the PDGF-B isoform.

CONCLUSION

PDGF-D signaling in pMF and HSC is identical to that of PDGF-B by binding to both PDGFR-α and -β.

Schip1 is a novel podocyte foot process protein that mediates actin cytoskeleton rearrangements and forms a complex with Nherf2 and ezrin

Background

Podocyte foot process effacement accompanied by actin cytoskeleton rearrangements is a cardinal feature of many progressive human proteinuric diseases.

Results

By microarray profiling of mouse glomerulus, SCHIP1 emerged as one of the most highly enriched transcripts. We detected Schip1 protein in the kidney glomerulus, specifically in podocytes foot processes. Functionally, Schip1 inactivation in zebrafish by morpholino knock-down results in foot process disorganization and podocyte loss leading to proteinuria. In cultured podocytes Schip1 localizes to cortical actin-rich regions of lamellipodia, where it forms a complex with Nherf2 and ezrin, proteins known to participate in actin remodeling stimulated by PDGFβ signaling. Mechanistically, overexpression of Schip1 in vitro causes accumulation of cortical F-actin with dissolution of transversal stress fibers and promotes cell migration in response to PDGF-BB stimulation. Upon actin disassembly by latrunculin A treatment, Schip1 remains associated with the residual F-actin-containing structures, suggesting a functional connection with actin cytoskeleton possibly via its interaction partners. A similar assay with cytochalasin D points to stabilization of cortical actin cytoskeleton in Schip1 overexpressing cells by attenuation of actin depolymerisation.

Conclusions

Schip1 is a novel glomerular protein predominantly expressed in podocytes, necessary for the zebrafish pronephros development and function. Schip1 associates with the cortical actin cytoskeleton network and modulates its dynamics in response to PDGF signaling via interaction with the Nherf2/ezrin complex. Its implication in proteinuric diseases remains to be further investigated.

Stem Cells Cultured on Beta Tricalcium Phosphate (β-TCP) in Combination with Recombinant Human Platelet-Derived Growth Factor - BB (rh-PDGF-BB) for the Treatment of Human Infrabony Defects

Knowledge gained from the field of tissue engineering, helped to develop a biological substitute that promotes tissue regeneration. The usual biological substitute consists of stem cells, growth factors and an appropriate scaffold. The present randomized controlled clinical and radiographic study was undertaken to evaluate the effectiveness of mesenchymal stem cells cultured on beta tricalcium phosphate (β-TCP) in combination with rh-PDGF-BB in treatment of infrabony defect in humans. A total of 24 infrabony defects in 14 systemically healthy patients were selected for the present study. The selected defects exhibited a probing pocket depth (PPD) of ≥ 5 mm and depth of infrabony component ≥ 3 mm as assessed by clinical and radiographic measurements and later confirmed by intrasurgical measurement. Baseline measurements included were Plaque Index (PI), Papillary Bleeding Index (PBI), Probing Pocket Depth (PPD), Relative gingival marginal level (RGML), Relative Clinical Attachment Level (R-CAL) and Radiographic Defect Depth (DD) and linear bone growth (LBG). 6 weeks after initial therapy, the defects were randomly assigned to either test group or control group. The control group was treated by an open flap debridement (OFD) only, while the test group was treated by a Stem cells cultured on β-TCP in combination with rh-PDGF-BB. All the measurements recorded preoperatively were repeated at 6 months after the surgery. The efficacy of each treatment modality was investigated through statistical analysis. Mean probing pocket depth reduction was significantly greater in test group (4.50 ± 1.08 mm) compared to the OFD group (3.50 ± 0.90 mm). Mean gains in clinical attachment level was 3.91 ± 1.37 mm in the test group and 2.08 ± 0.90 mm in the control group. The mean increase in gingival recession (GR) was less in test group (0.58 ± 0.79 mm) compared to OFD group (1.4 ± 0.66 mm). Radiographic defect depth reduction was greater in the test group (3.50 ± 0.67 mm) with 88.33% defect fill compared to control group (1.83 ± 0.38 mm) with only 52.77% defect fill. Linear bone growth (LBG) was significantly improved by 3.58 mm in test group, while in control group, it was 1.83 mm. Regenerative approach using Stem cells cultured on β-TCP in combination with rh-PDGF-BB for the treatment of human infrabony defects resulted in a significant added benefit in terms of CAL gains, PPD reductions greater radiographic defect fill and improvement in Linear bone growth (LBG) compared to the OFD alone.

Goniolactone C, a styryl lactone derivative, inhibits PDGF-BB-induced vascular smooth muscle cell migration and proliferation via PDGFR/ERK signaling

Platelet-derived growth factor-BB (PDGF-BB) and its downstream effector, extracellular signal-regulated kinase 1/2 (ERK1/2) MAP kinase, initiate a multitude of biological effects, including vascular smooth muscle cell (VSMC) proliferation and migration, which are critical events in the initiation and development of restenosis following percutaneous transluminal coronary angioplasty (PTCA). Styryl lactones are natural products that have been demonstrated to possess anti-proliferative activities. Goniolactone C is a styryl lactone derivative that was first extracted from Goniothalamus cheliensis Hu. In the present study, we investigated the effects of goniolactone C on VSMC migration and proliferation. We found that goniolactone C preferentially interacted with cellular systems that rely on PDGF signaling but not those that rely on epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) signaling. Goniolactone C strongly inhibited PDGF-BB-induced VSMC migration and proliferation. goniolactone C-mediated inhibition of VSMC proliferation was associated with cell cycle arrest, while goniolactone C-mediated inhibition of VSMC migration was associated with the suppression of adhesion molecule expression. In addition, goniolactone C directly inhibited PDGFR-β kinase activity, thereby blocking the downstream effector of PDGF-BB. Thus, the results of the present study suggest a novel adjunctive pharmacological strategy that may be used to prevent angioplasty-related restenosis.

Beneficial effects of platelet-derived growth factor on hemorrhagic shock in rats and the underlying mechanisms

Studies have shown that local application of platelet-derived growth factor (PDGF) can be used for the treatment of acute and chronic wounds. We investigated if systemic application of PDGF has a protective effect on acute hemorrhagic shock in rats in the present study. Using hemorrhagic shock rats and isolated superior mesenteric arteries, the effects of PDGF-BB on hemodynamics, animal survival, and vascular reactivity as well as the roles of the gap junction proteins connexin (Cx)40 and Cx43, PKC, and Rho kinase were observed. PDGF-BB (1–15 μg/kg iv) significantly improved the hemodynamics and blood perfusion to vital organs (liver and kidney) as well as vascular reactivity and improved the animal survival in hemorrhagic shock rats. PDGF recovering shock-induced vascular hyporeactivity depended on the integrity of the endothelium and myoendothelial gap junction. Cx43 antisense oligodeoxynucleotide abolished these improving effects of PDGF, whereas Cx40 oligodeoxynucleotide did not. Further study indicated that PDGF increased the activity of Rho kinase and PKC as well as vascular Ca2+ sensitivity, whereas it did not interfere with the intracellular Ca2+ concentration in hypoxia-treated vascular smooth muscle cells. In conclusion, systemic application of PDGF-BB may exert beneficial effects on hemorrhagic shock, which are closely related to the improvement of vascular reactivity and hemodynamics. The improvement of PDGF-BB in vascular reactivity is vascular endothelium and myoendothelial gap junction dependent. Cx43, Rho kinase, and PKC play very important role in this process. These findings suggest that PDGF may be a potential measure to treat acute clinical critical diseases such as severe trauma, shock, and sepsis.

NR4A1 promotes PDGF-BB-induced cell colony formation in soft agar

The fibroblast mitogen platelet-derived growth factor -BB (PDGF-BB) induces a transient expression of the orphan nuclear receptor NR4A1 (also named Nur77, TR3 or NGFIB). The aim of the present study was to investigate the pathways through which NR4A1 is induced by PDGF-BB and its functional role. We demonstrate that in PDGF-BB stimulated NIH3T3 cells, the MEK1/2 inhibitor CI-1040 strongly represses NR4A1 expression, whereas Erk5 downregulation delays the expression, but does not block it. Moreover, we report that treatment with the NF-κB inhibitor BAY11-7082 suppresses NR4A1 mRNA and protein expression. The majority of NR4A1 in NIH3T3 was found to be localized in the cytoplasm and only a fraction was translocated to the nucleus after continued PDGF-BB treatment. Silencing NR4A1 slightly increased the proliferation rate of NIH3T3 cells; however, it did not affect the chemotactic or survival abilities conferred by PDGF-BB. Moreover, overexpression of NR4A1 promoted anchorage-independent growth of NIH3T3 cells and the glioblastoma cell lines U-105MG and U-251MG. Thus, whereas NR4A1, induced by PDGF-BB, suppresses cell growth on a solid surface, it increases anchorage-independent growth.

PDGF-BB does not accelerate healing in diabetic mice with splinted skin wounds

Topical application of platelet-derived growth factor-BB (PDGF-BB) is considered to accelerate tissue repair of impaired chronic wounds. However, the vast literature is plagued with conflicting reports of its efficacy in animal models and this is often influenced by a wide array of experimental variables making it difficult to compare the results across the studies. To mitigate the confounding variables that influence the efficacy of topically applied PDGF-BB, we used a controlled full thickness splinted excisional wound model in db/db mice (type 2 diabetic mouse model) for our investigations. A carefully-defined silicone-splinted wound model, with reduced wound contraction, controlled splint and bandage maintenance, allowing for healing primarily by reepithelialization was employed. Two splinted 8 mm dorsal full thickness wounds were made in db/db mice. Wounds were topically treated once daily with either 3 µg PDGF-BB in 30 µl of 5% PEG-PBS vehicle or an equal volume of vehicle for 10 days. Body weights, wound contraction, wound closure, reepithelialization, collagen content, and wound bed inflammation were evaluated clinically and histopathologically. The bioactivity of PDGF-BB was confirmed by in vitro proliferation assay. PDGF-BB, although bioactive in vitro, failed to accelerate wound healing in vivo in the db/db mice using the splinted wound model. Considering that the predominant mechanism of wound healing in humans is by re-epeithelialization, the most appropriate model for evaluating therapeutics is one that uses splints to prevent excessive wound contraction. Here, we report that PDGF-BB does not promote wound closure by re-epithelialization in a murine splinted wound model. Our results highlight that the effects of cytoactive factors reported in vivo ought to be carefully interpreted with critical consideration of the wound model used.

Lutein inhibits the migration of retinal pigment epithelial cells via cytosolic and mitochondrial Akt pathways (lutein inhibits RPE cells migration)

During the course of proliferative vitreoretinopathy (PVR), the retinal pigment epithelium (RPE) cells will de-differentiate, proliferate, and migrate onto the surfaces of the sensory retina. Several studies have shown that platelet-derived growth factor (PDGF) can induce migration of RPE cells via an Akt-related pathway. In this study, the effect of lutein on PDGF-BB-induced RPE cells migration was examined using transwell migration assays and Western blot analyses. We found that both phosphorylation of Akt and mitochondrial translocation of Akt in RPE cells induced by PDGF-BB stimulation were suppressed by lutein. Furthermore, the increased migration observed in RPE cells with overexpressed mitochondrial Akt could also be suppressed by lutein. Our results demonstrate that lutein can inhibit PDGF-BB induced RPE cells migration through the inhibition of both cytoplasmic and mitochondrial Akt activation.

Using growth factors in human extraction sockets: a histologic and histomorphometric evaluation of short-term healing

PURPOSE

Ridge preservation protocols reduce crestal remodeling after tooth extraction. There is insufficient evidence on bone grafting in combination with platelet-rich plasma (PRP) or recombinant human platelet-derived growth factor (rhPDGF-BB). The aim of this study is to evaluate healing of grafted and nongrafted sockets and the effect of PRP and rhPDGF-BB on early remodeling.

MATERIALS AND METHODS

Forty-one patients whose treatment plan included extraction of anterior or premolar teeth were randomized into four groups. Group 1: collagen plug (control). Group 2: mineralized freeze-dried bone allograft (FDBA)/β-tricalcium phosphate (β-TCP)/collagen plug. Group 3: FDBA/β-TCP/PRP/collagen plug. Group 4: FDBA/β-TCP/rhPDGF-BB/collagen plug. At 8 weeks, a core was harvested from the center of 41 sockets. Histomorphometric analysis took place. Differences were analyzed using one-way analysis of variance (ANOVA) or chi-square tests for continuous and categorical data. Pairwise comparisons were tested using least squares means. Spearman correlation coefficients were used to evaluate the relationship of bone growth with potential confounders. A P value < .05 was considered statistically significant.

RESULTS

ANOVA did not indicate statistical significance in age, gender, smoking, ethnicity, or race distribution. Significant differences in tissue distribution were identified between groups and between different thirds of harvested core. More new bone and amorphous organic matrix was noted in the control group. In sites where bone graft was combined with growth factors, the amount of residual particles was less than in sites where bone graft was used alone.

CONCLUSIONS

Inclusion of bone replacement graft suppressed new bone formation during early healing. Inclusion of PRP and rhPDGF-BB produced less residual bone graft material, indicating more rapid turnover of bone graft. All treatment modalities achieved a significant amount of new vital bone at 8 weeks postextraction.

Rapid granulation tissue regeneration by intracellular ATP delivery--a comparison with Regranex

This study tests a new intracellular ATP delivery technique for tissue regeneration and compares its efficacy with that of Regranex. Twenty-seven adult New Zealand white rabbits each underwent minimally invasive surgery to render one ear ischemic. Eight wounds were then created: four on the ischemic and four on the normal ear. Two wounds on one side of each ear were treated with Mg-ATP encapsulated lipid vesicles (ATP-vesicles) while the two wounds on the other side were treated with Regranex. Wound healing time was shorter when ATP-vesicles were used. The most striking finding was that new tissue growth started to appear in less than 1 day when ATP-vesicles were used. The growth continued and covered the wound area within a few days, without the formation of a provisional matrix. Regranex-treated wounds did not have this growth pattern. In wounds treated by ATP-vesicles, histologic studies revealed extremely rich macrophage accumulation, along with active proliferating cell nuclear antigen (PCNA) and positive BrdU staining, indicating in situ macrophage proliferation. Human macrophage culture suggested direct collagen production. These results support an entirely new healing process, which seems to have combined the conventional hemostasis, inflammation, and proliferation phases into a single one, thereby eliminating the lag time usually seen during healing process.