Platelet-derived growth factor-AA-mediated functional angiogenesis in the rat epigastric island flap after genetic modification of fibroblasts is ischemia dependent

VEGF and Other Gene Therapies Improve Flap Survival-A Systematic Review and Meta-Analysis of Preclinical Studies

Surgical flaps are basic tools in reconstructive surgery. Their use may be limited by ischemia and necrosis. Few therapies address or prevent them. Genetic therapy could improve flap outcomes, but primary studies in this field present conflicting results. This systematic review and meta-analysis aimed to appraise the efficacy of external gene delivery to the flap for its survival in preclinical models. This review was registered with PROSPERO (CRD42022359982). PubMed, Embase, Web of Science, and Scopus were searched to identify studies using animal models reporting flap survival outcomes following any genetic modifications. Random-effects meta-analysis was used to calculate mean differences in flap survival with accompanying 95% CI. The risk of bias was assessed using the SYRCLE tool. Subgroup and sensitivity analyses were performed to ascertain the robustness of primary analyses, and the evidence was assessed using the GRADE approach. The initial search yielded 690 articles; 51 were eventually included, 36 of which with 1576 rats were meta-analyzed. VEGF gene delivery to different flap types significantly improved flap survival area by 15.66% (95% CI 11.80-19.52). Other interventions had smaller or less precise effects: PDGF-13.44% (95% CI 3.53-23.35); VEGF + FGF-8.64% (95% CI 6.94-10.34); HGF-5.61% (95% CI 0.43-10.78); FGF 3.84% (95% CI 1.13-6.55). Despite considerable heterogeneity, moderate risk of bias, and low quality of evidence, the efficacy of VEGF gene therapy remained significant in all sensitivity analyses. Preclinical data indicate that gene therapy is effective for increasing flap survival, but further animal studies are required for successful clinical translation.

Lysine demethylase 2A promotes stemness and angiogenesis of breast cancer by upregulating Jagged1

Alterations of histone methylation dynamically regulated by methyltransferases and demethylases are frequently found in human cancers. Here, we showed that expression of lysine demethylase 2A (KDM2A) is markedly increased in human breast cancer and its overexpression is associated with tumor progression and poor prognosis. Knockdown of KDM2A in breast cancer cells reduced proliferation but not viability. Gene set enrichment analysis revealed that inhibition of KDM2A down-regulates angiogenic genes with concurrent reduction of Jagged1 (JAG1), NOTCH1 and HEY1 in the NOTCH signaling. Chromatin immunoprecipitation- quantitative polymerase chain reaction (ChIP-qPCR) demonstrated the binding of KDM2A to the JAG1 promoter and the increase of methylation of Lys-36 of histone H3 (H3K36) in KDM2A-depleted MDA-MB-231 cells. Tumorsphere formation was significantly reduced in KDM2A-depleted cells which could be reversed by ectopic expression of JAG1. A selective KDM2A inhibitor daminozide also decreased the number of tumorsphere and the number of CD24-/CD44hi cells. In addition, daminozide acted synergistically with cisplatin in cell killing. We identified SOX2 as a direct transcriptional target of KDM2A to promote cancer stemness. Depletion of KDM2A in MDA-MB-231 cells attenuated NOTCH activation and tube formation in co-cultured endothelial cells. Two pro-angiogenic factors JAG1 and PDGFA are key mediators for KDM2A to enhance angiogenesis. Finally, inhibition of KDM2A significantly decreased tumor growth and angiogenesis in orthotopic animal experiments. Collectively, we conclude that KDM2A functions as an oncogene in breast cancer by upregulating JAG1 to promote stemness, chemoresistance and angiogenesis.

XBP1 splicing triggers miR-150 transfer from smooth muscle cells to endothelial cells via extracellular vesicles

The interaction between endothelial cells (ECs) and smooth muscle cells (SMCs) plays a critical role in the maintenance of vessel wall homeostasis. The X-box binding protein 1 (XBP1) plays an important role in EC and SMC cellular functions. However, whether XBP1 is involved in EC-SMC interaction remains unclear. In this study, In vivo experiments with hindlimb ischemia models revealed that XBP1 deficiency in SMCs significantly attenuated angiogenesis in ischemic tissues, therefore retarded the foot blood perfusion recovery. In vitro studies indicated that either overexpression of the spliced XBP1 or treatment with platelet derived growth factor-BB up-regulated miR-150 expression and secretion via extracellular vesicles (EVs). The XBP1 splicing-mediated up-regulation of miR-150 might be due to increased stability. The SMC-derived EVs could trigger EC migration, which was abolished by miR-150 knockdown in SMCs, suggesting miR-150 is responsible for SMC-stimulated EC migration. The SMC-derived miR-150-containing EVs or premiR-150 transfection increased vascular endothelial growth factor (VEGF)-A mRNA and secretion in ECs. Both inhibitors SU5416 and LY294002 attenuated EVs-induced EC migration. This study demonstrates that XBP1 splicing in SMCs can control EC migration via SMC derived EVs-mediated miR-150 transfer and miR-150-driven VEGF-A/VEGFR/PI3K/Akt pathway activation, thereby modulating the maintenance of vessel wall homeostasis.

Microparticles mediated cross-talk between tumoral and endothelial cells promote the constitution of a pro-metastatic vascular niche through Arf6 up regulation

The tumor stroma plays an essential role in tumor growth, resistance to therapy and occurrence of metastatic phenotype. Tumor vessels have been considered as passive conducts for nutrients but several studies have demonstrated secretion of pro-tumoral factors by endothelial cells. The failure of anti-angiogenic therapies to meet expectations raised by pre-clinical studies prompt us to better study the cross-talk between endothelial and cancer cells. Here, we hypothesized that tumor cells and the endothelium secrete bio-active microparticles (MPs) participating to a functional cross-talk. We characterized the cancer cells MPs, using breast and ovarian cancer cell lines (MCF7, MDA-MB231, SKOV3, OVCAR3 and a primary cell lines, APOCC). Our data show that MPs from mesenchymal-like cell lines (MDA-MB231, SKOV3 and APOCC) were able to promote an activation of endothelial cells through Akt phosphorylation, compared to MPs from epithelial-like cell lines (OVCAR3 and MCF7). The MPs from mesenchymal-like cells contained increased angiogenic molecules including PDGF, IL8 and angiogenin. The endothelial activation was associated to increased Arf6 expression and MPs secretion. Endothelial activation functionalized an MP dependent pro-tumoral vascular niche promoting cancer cells proliferation, invasiveness, stem cell phenotype and chemoresistance. MPs from cancer and endothelial cells displayed phenotypic heterogeneity, and participated to a functional cross-talk where endothelial activation by cancer MPs resulted in increased secretion of EC-MPs sustaining tumor cells. Such cross-talk may play a role in perfusion independent role of the endothelium.

Effects of taurine on reperfusion injury

Taurine is an organic acid, which has a very important function in the human body. Recently, the antioxidant property of taurine has been much emphasised. In this study, the gracilis muscle flap model was used to investigate the effect of taurine in ischaemia/reperfusion injury in rats. Totally 32 Sprague-Dawley rats were divided into two groups: control group (n = 16) and the treatment group with taurine (n = 16). After elevation of the gracilis muscle flap, 4 h of ischaemia was performed in both groups. Thirty min before the reperfusion, taurine (200 mg kg(-1)) was injected intravenously. After 24 h of reperfusion, the amount of malondialdehyde (MDA), tissue water content and flap viability were evaluated. After 72 h of reperfusion, histological findings were evaluated. Amount of MDA and tissue water content were significantly lower (p < 0.005), and the flap viability was significantly higher (p < 0.005) in the treatment group 24 h after reperfusion. On comparing the outcomes of histological analysis between control and treatment groups, the amounts of collagen, fibroblast and angiogenesis in treatment group were significantly higher than those in the control group. However, the amount of polymorphonuclear leucocyte and tissue necrosis in the treatment group were significantly lower than in the control group. Our results showed that taurine played an important role in the process of ischaemia/reperfusion injury and presented certain protective effects with the improvement in flap survival after ischaemia/reperfusion injury.

Anti-angiogenic effects of imatinib target smooth muscle cells but not endothelial cells

Knowing that progesterone up-regulates PDGF-A, which plays a relevant role in angiogenesis, and that imatinib mesylate targets PDGF receptor tyrosine kinase activity, the aim of the present study was to examine the effects of imatinib on Human Aortic Smooth Muscle Cells (HAoSMC) and Human Umbilical Vein Endothelial Cells (HUVEC) after incubation with progesterone. Expression of phosphorylated (activated) PDGFR-alpha was detected in HAoSMC, but in a very low extent in HUVEC. In agreement with the lack of active PDGFR-alpha, imatinib was unable to prevent HUVEC growth, survival or migration ability. In contrast, HAoSMC viability and proliferation were effectively inhibited by imatinib, as evaluated by MTT and BrdU incorporation assay, respectively. Corroborating these findings, a significant increase in the percentage of apoptotic cells was also observed after treatment with imatinib. Cell migration assays also showed a reduction in the migratory ability after incubation with imatinib. Altogether, these facts reveal that imatinib is able to affect HAoSMC survival, growth and migration. Furthermore, incubation with recombinant PDGF as well as, with progesterone seems to sustain PDGFR-alpha activity, prompting these cells to the inhibitory action of imatinib. These findings were restricted to smooth muscle cells, leading to the assumption that imatinib is probably preventing vessel stabilization, a crucial event for neovascular maturation. Our findings indicate that imatinib might be a good therapeutic agent against atherosclerosis and other vascular-associated disorders that carry in common smooth muscle cells abnormal growth.

Elucidating progesterone effects in breast cancer: Cross talk with PDGF signaling pathway in smooth muscle cell

Several studies indicate that progesterone exerts relevant effects in breast tissue. However, the exact role of this steroid in breast cancer development and progression has not been elucidated. Here, we show that platelet-derived growth factor (PDGF)-A is one of the progesterone target genes on breast cancer MCF7 and T47D cells. A paracrine role for PDGF-A was investigated, since its receptor expression was down-regulated from breast cancer cells. Progesterone increased PDGF-A protein release as evaluated by Western blotting and ELISA. Medium from Progesterone-treated MCF7 cells resulted in phosphorylation of smooth muscle cells PDGF receptor alpha. This effect was not observed after treatment with PDGF inhibitor. MCF7 cells-secreted PDGF-A was able to increase smooth muscle cell viability and proliferation and decrease apoptosis, effects that were prevented by the use of a PDGF-A neutralizing antibody. Notably, cell invasion was not influenced by PDGF-A secreted by MCF7 cells. Our results elucidated for the first time the cross talk between progesterone and PDGF signaling pathway. The fact that MCF7-secreted PDGF elicited crucial roles in vascular wall smooth muscle cells, suggested a paracrine pathway for progesterone. Targeting these progesterone-induced processes may provide novel therapeutic strategies for hormone-dependent human breast cancer.

PDGF Gene Therapy Enhances Expression of VEGF and bFGF Genes and Activates the NF-??B Gene in Signal Pathways in Ischemic Flaps

BACKGROUND

Gene therapy is a novel approach for enhancing the viability of ischemic flaps. Expression of growth factor genes pertinent to angiogenesis and activation of genes of relevant signal pathways are imperative for improving flap viability. The authors investigated the gene expression profiles of growth factors and signal transduction pathways in ischemic flaps after PDGF gene therapy.

METHODS

Twenty Sprague-Dawley rats were divided into two groups. The experimental group (n = 10) received the plasmid vector containing the PDGF cDNA injected into the dermis of the flap area, whereas the control group (n = 10) received the physiologic saline. Seven days later, a dorsal random flap was raised. Seven days after surgery, flap viability was assessed, and expression of VEGF, bFGF, TGF-beta1, NF-kappaB, Erk2, Stat1, and Smad2 genes of the NF-kappaB, MAPK, JAK-STAT, and Smad pathways was assessed by quantitative analysis of the products of reverse-transcriptase polymerase chain reaction.

RESULTS

Transfer of exogenous PDGF gene significantly improved flap viability (p = 0.011). Levels of expression of VEGF and bFGF genes in the flap were significantly elevated after PDGF gene transfer (p = 0.0001 and p = 0.001, respectively). Expression of the NF-kappaB gene was significantly elevated (p = 0.041). In contrast, expression of TGF-beta1, and Erk2, Stat1, and Smad2 genes was not changed.

CONCLUSIONS

Transfer of exogenous PDGF gene to ischemic flaps promotes expression of VEGF and bFGF genes and activation of NF-kappaB gene in addition to its effects on the PDGF gene. The finding implies that transfer of the gene of one growth factor ultimately improves the expression of the genes of multiple growth factors. Activation of the NF-kappaB gene suggests that the NF-kappaB pathway may be important in enhancement of flap viability and will likely be a target of future efforts of regulation of signaling process in treatment of ischemic flaps.

Growth factors and flap survival

Growth factors are members of a large functional group of polypeptide regulatory molecules that influence the biological activities of responsive cells. In the last decade, the use of a variety of growth factors as therapeutic agents to improve wound healing and the viability of ischemic skin flaps has aroused considerable interest. Here, we review the literature concerning the regulation of growth factors in a flap, the role of angiogenesis in flap survival, the effect of growth factors on the metabolism of a flap, and angiogenesis in flap prefabrication and maturation. The potential application of growth factors in gene therapies is also reviewed.

Gene therapy in flap survival

Growth factors are members of a large functional group of polypeptide regulatory molecules that exert a powerful influence on all phases of wound healing and repair through interactions with specific cell surface receptors. The use of growth factors to improve wound healing and the viability of ischemic skin flaps has been well-documented throughout the last decade. In this article, we review the literature concerning the use gene therapy in flap survival, including the various methods employed to transplant plasmids or viruses capable of coding and producing growth factors in ischemic tissue.

Evolving revascularization approaches for myocardial ischemia

Stable angina pectoris secondary to ischemic heart disease is a common and disabling condition. Medical therapy aims to relieve symptoms, improve exercise capacity, and decrease cardiac events by reducing myocardial oxygen demand or improving coronary blood supply to the ischemic myocardium. If medical treatment is inadequate, invasive revascularization procedures to improve coronary perfusion are considered. Percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass graft (CABG) surgery are well-established and widely used myocardial revascularization techniques. Recent advances in PTCA have attempted to address the problem of restenosis, initially through the deployment of bare metal intracoronary stents and, more recently, with drug-eluting stents. Developments in CABG have focused on reducing the invasiveness of the procedure and minimizing the incidence of serious complications. Refinements include the use of mechanical stabilizers, endoscopic harvesting of conduit vessels, robotic telemanipulation systems, and fully automated anastomotic devices. Surgical laser transmyocardial revascularization and therapeutic angiogenesis represent newer approaches to coronary revascularization. Therapeutic angiogenesis aims to deliver an angiogenic growth factor or cytokine to the myocardium to stimulate collateral blood vessel growth throughout the ischemic tissue. The angiogenic factor may be administered as a recombinant protein or as a transgene within a plasmid or gene-transfer vector. Ongoing angiogenic gene therapy clinical trials are evaluating which factors, vectors, and delivery techniques hold the greatest promise for management of patients with chronic stable angina.

Angiogenic effects of injected VEGF165 and sVEGFR-1 (sFLT-1) in a rat flap model

BACKGROUND

Injections of single-dose vascular endothelial growth factor (VEGF)(165) have been advocated as a therapeutic tool for angiogenesis in ischemic flaps. We challenged this thesis by employing both VEGF(165) and vascular endothelial growth factor receptor-1 (VEGFR-1) (for competitive inhibition of VEGF signal transduction) in different experimental settings of an ischemic rat flap model.

MATERIAL AND METHODS

80 isogenic rats were divided in two groups of 40 animals (groups 1A-1D and 2A-2D). The ischemic target was a 7 x 7-cm epigastric island flap, based on the right inferior epigastric pedicle. Group 1 received flap treatment 1 week prior to flap elevation by test substance injection into its flap panniculus carnosus: 1 ml NaCl 0.9% (1A), 1 ml Dulbecco's modified Eagle's medium (1B), 1.0 microg VEGF(165) (1C), and 10 microg sFLT-1 with 1.0 microg VEGF(165) (1D). sFLT-1 is a soluble receptor for VEGF and is able to prevent VEGF signaling through the cell surface receptor. Group 2 had the same flap treatment at the day of flap elevation.

RESULTS

In group 1C we found the most vital flap tissue, without reaching significance. Compared with group 1D, however, significantly more flap tissue maintained vital. In groups 2A-2D, no significant results were found with respect to flap survival.

CONCLUSIONS

Local application of single-dose VEGF(165) 1 week prior to ischemia dose not have significant clinical angiogenic effects. In this experimental setting, VEGF(165)-induced angiogenic effects can be significantly inhibited by adding sFLT1 in vivo. A single-dose of VEGF(165) under ischemic conditions causes no significantly better flap survival in this model.