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Preeclampsia is characterized by the development of elevated blood pressure during the second and third trimesters of pregnancy that is accompanied by end organ dysfunction. The pathogenesis of preeclampsia is multifactorial but is commonly characterized by endothelial dysfunction and the overproduction of antiangiogenic factors, including the soluble VEGF (vascular endothelial growth factor) receptor sFlt-1 (soluble Fms-like tyrosine kinase receptor 1). Previously, administration of exogenous VEGF-A, bound to a carrier protein called ELP (elastin-like polypeptide), significantly reduced free sFlt-1 levels and attenuated the hypertensive response in a rodent model of preeclampsia. However, VEGF-A administration induces multifactorial effects mediated through its direct activation of the Flk-1 receptor. In response to this, we developed a therapeutic chimera using ELP bound to VEGF-B, a VEGF isoform that binds to sFlt-1 but not to Flk-1. The purpose of this study was to evaluate the in vitro activity and pharmacological properties of ELP-VEGF-B and to test its efficacy in the reduced uterine perfusion pressure rat model of placental ischemia. ELP-VEGF-B was less potent than ELP-VEGF-A in stimulation of endothelial cell proliferation and matrix invasion, indicating that it is a weaker angiogenic driver. However, after repeated subcutaneous administration in pregnant rats, ELP-VEGF-B was maternally sequestered and reduced blood pressure when compared with saline treated animals following induction of placental ischemia (123.38±11.4 versus 139.98±10.56 mm Hg, P =0.0129). Blood pressure reduction was associated with a restoration of the angiogenic capacity of plasma from rats treated with ELP-VEGF-B. ELP-VEGF-B is a nonangiogenic, maternally sequestered protein with potential efficacy for treatment of preeclampsia.

The pregnant Dahl salt-sensitive (S) rat is an established preclinical model of superimposed spontaneous preeclampsia characterized by exacerbated hypertension, increased urinary protein excretion, and increased fetal demise. Because of the underlying immune system dysfunction present in preeclamptic pregnancies in humans, we hypothesized that the pregnant Dahl S rat would also have an altered immune status. Immune system activation was assessed during late pregnancy in the Dahl S model and compared with healthy pregnant Sprague-Dawley (SD) rats subjected to either a sham procedure or a procedure to reduce uterine perfusion pressure (RUPP). Circulating immunoglobulin and cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA) and Milliplex bead assay, respectively, and percentages of circulating, splenic, and placental immune cells were determined using flow cytometry. The pregnant Dahl S rat exhibited an increase in CD4+ T cells, and specifically TNFα+CD4+ T cells, in the spleen compared with virgin Dahl S rats. The Dahl also had increased neutrophils and decreased B cells in the peripheral blood as compared with Dahl virgin rats. SD rats that received the RUPP procedure had increases in circulating monocytes and increased IFN-ɣ+CD4+ splenic T cells. Together these findings suggest that dysregulated T cell activity is an important factor in both the pregnant Dahl S rats and SD rats after the RUPP procedure.

Preeclampsia is a common obstetrical complication, hallmarked by new-onset hypertension. Believed to result from placental insufficiency and chronic placental ischemia, the symptoms of preeclampsia are caused by release of pathogenic factors from the placenta itself, although the mechanisms of their regulation are in many cases unknown. One potential mechanism is through changes in placental epigenetic chromatin modifications, particularly histone acetylation and DNA methylation. Here, we determined the effects of chronic ischemia on global epigenetic modifications in the rodent placenta in vivo and acute hypoxia in BeWo placental trophoblast cells in vitro. Placental insufficiency via uterine artery restriction increased maternal blood pressure and fetal demise while decreasing placental and fetal mass. Global placental histone H3 acetylation levels were significantly decreased at H3 K9, K14, K18, K27, and K56. Interestingly, when BeWo-immortalized placental trophoblast cells were cultured in oxygen concentrations mimicking healthy and ischemic placentas, there was a significant increase in acetylated at K9, K18, K27, and K56. This was associated with a small but significant decrease in placental acetyl-CoA, suggesting depletion in the source of acetyl group donors. Finally, while global methylation of cytosine from placental DNA was low in both groups of animals (

BACKGROUND Preeclampsia is a pregnancy complication which manifests as new-onset hypertension, proteinuria, and a spectrum of other symptoms. While the underlying causes are still a subject of much debate, it is commonly believed that placental ischemia is a central cause. The ischemic placenta secretes factors which are believed to be responsible for the maternal syndrome; most notably the anti-angiogenic protein soluble fms-like tyrosine kinase 1 (sFlt-1). We have reported that induction of the carbon monoxide (CO) producing protein heme oxygenase-1 restored angiogenic imbalance and reduced blood pressure in a rat model of placental ischemia, and that CO blocks hypoxia-induced sFlt-1 production from placental tissue in vitro. We therefore hypothesized that direct administration of CO by a CO-releasing molecule (CORM) would blunt the placental ischemia-induced increase in sFlt-1 and thus the hypertension characteristic of this model. METHODS We administered a soluble CO donor molecule (CORM-3) daily i.v. in control animals or those undergoing placental ischemia from GD14. Blood pressure and renal function were measured on GD19, and angiogenic markers measured by ELISA. RESULTS Interestingly, though we found that CORM administration significantly blunted the hypertensive response to placental ischemia, there was no concomitant normalization of sFlt-1 in either the placenta or maternal circulation. We did find, however, that CORM administration caused a significant increase in glomerular filtration rate, presumably by vasodilation of the renal arteries and increased renal plasma flow. CONCLUSIONS All in all these data suggest that administration of CO by CORMs do lower blood pressure during placental ischemia mechanisms independent of changes in angiogenic balance.

Perhaps no disease of pregnancy has been more thoroughly studied than pre-eclampsia (PE), and yet despite all of our efforts we are only beginning to understand the molecular mechanisms which underpin the disease. Many people are surprised by the frequency of PE in the population, as it is believed to occur in approximately one pregnancy out of 20 in the United States, with similar rates throughout the developed world. In severe cases the disorder can progress to eclampsia, which is characterized by maternal seizures and can lead to death. PE can only be treated by ending the pregnancy, often by inducing labour prior to term, making PE a leading cause of premature birth and all of the associated health complications which accompany it. All in all, PE is one of the leading causes of maternal and fetal morbidity and mortality. It is now also becoming apparent that PE disposes both the mother and the baby to increased risk of cardiovascular disease throughout life, meaning that we still don't fully understand the long-term implications of the disease.

Introduction Preeclampsia is a common pregnancy disorder which is characterized by new onset hypertension and endothelial dysfunction. Despite efforts to determine the causal factors of this disease, little progress has been made in discerning the etiology. The hypoxic and ischemic placenta, however, is generally accepted as the source for secreted factors in the maternal circulation, such as sFLT-1, which drive the maternal syndrome. Methods Using BeWo placental trophoblast cells, we measured the role of hypoxia on sFLT-1 mRNA as well as protein production. We also exposed the cells to treatment with heparin and heparanase inhibitor OGT-2115. Results We found that under hypoxic conditions mRNA levels of sFLT-1 were unchanged compared to normoxic controls. Although the message level did not differ under hypoxic conditions, the sFLT-1 release into the media was significantly greater in hypoxia. Additionally, we found that sFLT-1 is able to bind heparan strands in the extracellular matrix with its heparin binding site. These heparan strands can be cleaved by the extracellular enzyme heparanase. We found that heparanase expression was significantly increased in hypoxia, and inhibiting the actions of heparanase attenuated the release of sFLT-1 into the media. Discussion While the placenta remains a source of sFLT-1, the mechanism of increased circulating sFLT-1 may differ than simple upregulation of the protein. These data demonstrate the potential importance of the role heparanase may play in releasing previously made sFLT-1 into the maternal circulation.

Preeclampsia (PE) is a pregnancy-specific, multisystemic disorder that occurs in roughly 5% of pregnancies in the United States.1,2 The rates of PE in the United States have been steadily rising over the past 30 years with PE being a leading cause of maternal and fetal/neonatal morbidity and mortality.3 Women with PE, as well as their offspring, are at greater risk for chronic diseases, including cardiovascular disease (CVD) later in life.4,5 Despite being the leading cause of maternal death and a major contributor to maternal and perinatal morbidity, drug treatment to prevent PE is at best minimally effective, and current management therapies have significant limitations. In fact, at present, delivery is considered the only effective intervention for treating PE6 and even then PE may continue in the postpartum period or present de novo.7 The lack of progress in identifying new therapeutic targets for the treatment of PE is due in part to a paucity of animal models that address the heterogeneity of human PE as well as lack of understanding of basic disease mechanisms. There are no models of spontaneously developing PE in animals. Developing novel animal models to mimic human PE, identifying biomarkers to predict PE, conducting basic studies to better understand disease mechanisms, and ultimately, developing novel therapeutic strategies are clearly needed. The National Heart, Lung, and Blood Institute (NHLBI), in collaboration with the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), held a workshop to examine the topic of Predicting, Preventing and Treating Preeclampsia on May 21–22, 2018, in Bethesda, MD. Speakers were chosen for expertise in general areas identified as important and cutting edge by the organizers. Specific topics discussed during the workshop were: i) pathophysiology of PE; ii) immunological origins of PE; iii) how to define subsets of PE; iv) biomarkers; v) nutritional factors; vi) genetics and epigenetics; vii) animal models; viii) collaboration, harmonization, sharing large data and samples sets in the study of PE; ix) periconceptional contributors to pathophysiology; x) clinical risk factors for PE; xi) novel therapies for the prevention and treatment of PE; xii) long-term cardiovascular consequences of PE and xiii) patient perspectives. Based on these discussions, recommendations for future research were developed in the following general areas: 1) Pathophysiology of PE; 2) Impact of PE on long-term health outcomes; 3) Biomarkers and diagnostic tools; 4) Translational research and novel treatment strategies. The purpose of this report is to summarize the scientific research recommendations arising from deliberations of the invited speakers and meeting attendees. These research recommendations are summarized in Table 1 (which is keyed to the manuscript text) and are presented in no particular order of priority. The goal of the recommendations is to provide guidance regarding future research on PE and its short- and long-term consequences. Table1: Summary of recommendations from the NIH workshop on “Predicting, Preventing and Treating Preeclampsia”

Preeclampsia (PE) is a form of gestational hypertension that complicates ∼5% of pregnancies worldwide. Over 70% of the fatal cases of PE are attributed to cerebral oedema, intracranial haemorrhage and eclampsia. The aetiology of PE originates from abnormal remodelling of the maternal spiral arteries, creating an ischaemic placenta that releases factors that drive the pathophysiology. An initial neurological outcome of PE is the absence of the autonomically regulated cardiovascular adaptations to pregnancy. PE patients exhibit sympathetic overactivation, in comparison with both normotensive pregnant and hypertensive non-pregnant females. Moreover, PE diminishes baroreceptor reflex sensitivity (BRS) beyond that observed in healthy pregnancy. The absence of the cardiovascular adaptations to pregnancy, combined with sympathovagal imbalance and a blunted BRS leads to life-threatening neurological outcomes. Behaviourally, the increased incidences of maternal depression, anxiety and post-traumatic stress disorder (PTSD) in PE are correlated to low fetal birth weight, intrauterine growth restriction (IUGR) and premature birth. This review addresses these neurological consequences of PE that present in the gravid female both during and after the index pregnancy.

Preeclampsia is a disorder of pregnancy characterized by new-onset hypertension and maternal endothelial dysfunction. Although the origins of the disease are unclear, it is believed that placental hypoxia/ischemia leads to the release of soluble factors which cause the maternal syndrome. The best characterized factor elevated in PE is soluble fms-like Tyrosine Kinase-1 (sFlt-1), a soluble splice variant of the VEGFR1 receptor which acts as a decoy receptor; and thus a VEGFA antagonist. Overproduction of this protein is believed to be a major contributor to the maternal endothelial dysfunction, causing much speculation that VEGF supplementation could be an effective supplementation could be an effective therapy. Recently we described a VEGFA chimera therapy (ELP-VEGFA) which alleviated the hypertension associated with placental ischemia in a rodent model, but also led to a dramatic increase in maternal circulating sFlt-1. Here we tested the hypothesis that chimeric VEGF would significantly increase sFlt-1 production from placental tissue in vitro. Surprisingly, there was no effect of ELP-VEGF on sFlt-1 production in either BeWo placental trophoblasts or in rodent placental tissue explants at either the mRNA or protein level. Instead, we found that vascular endothelial cells (HUVECs) responded robustly to ELP-VEGFA at the protein (6593 ± 199 vs 14547 ± 364 pg/ml, p

Preeclampsia is a pregnancy-induced hypertensive disorder resulting from abnormal placentation, which causes factors such as sFlt-1 to be released into the maternal circulation. Though anti-hypertensive drugs and magnesium sulfate can be given in an effort to moderate symptoms, the syndrome is not well controlled. A hallmark characteristic of preeclampsia, especially early-onset preeclampsia, is angiogenic imbalance resulting from an inappropriately upregulated sFlt-1 acting as a decoy receptor binding vascular endothelial growth factor (VEGF) and placental growth factor (PlGF), reducing their bioavailability. Administration of sFlt-1 leads to a preeclamptic phenotype, and several models of preeclampsia also have elevated levels of plasma sFlt-1, demonstrating its role in driving the progression of this disease. Treatment with either VEGF or PlGF has been effective in attenuating hypertension and proteinuria in multiple models of preeclampsia. VEGF, however, may have overdose toxicity risks that have not been observed in PlGF treatment, suggesting that PlGF is a potentially safer therapeutic option. This review discusses angiogenic balance as it relates to preeclampsia and the studies which have been performed in order to alleviate the imbalance driving the maternal syndrome.

Purpose One of the most common, and most vexing, obstetric complications is preeclampsia—a major cause of maternal and perinatal morbidity. Hallmarked by new-onset hypertension and a myriad of other symptoms, the underlying cause of the disorder remains obscure despite intensive research into its etiology. Although the initiating events are not clear, one common finding in preeclamptic patients is failure to remodel the maternal arteries that supply the placenta, with resulting hypoxia/ischemia. Intensive research over the past 2 decades has identified several categories of molecular dysfunction resulting from placental hypoxia, which, when released into the maternal circulation, are involved in the spectrum of symptoms seen in these patients—in particular, angiogenic imbalance and the activation of innate and adaptive immune responses. Despite these new insights, little in the way of new treatments for the management of these patients has been advanced into clinical practice. Indeed, few therapeutic options exist for the obstetrician treating a case of preeclampsia. Pharmacologic management is typically seizure prophylaxis, and, in severe cases, antihypertensive agents for controlling worsening hypertension. Ultimately, the induction of labor is indicated, making preeclampsia a leading cause of premature birth. Here, the molecular mechanisms linking placental ischemia to the maternal symptoms of preeclampsia are reviewed, and several areas of recent research suggesting new potential therapeutic approaches to the management of preeclampsia are identified.

Preeclampsia is a serious and common hypertensive complication of pregnancy, affecting ~5 to 8 % of pregnancies. The underlying cause of preeclampsia is believed to be placental ischemia, which causes secretion of pathogenic factors into the maternal circulation. While a number of these factors have been identified, it is likely that others remain to be elucidated. Here, we have utilized a relevant preclinical rodent model of placental ischemia-induced hypertension, the reduced uterine perfusion pressure (RUPP) model, to determine the effect of chronic placental ischemia on the underlying chorionic tissue and placental villi. Tissue from control and RUPP rats were isolated on gestational day 19 and mRNA from these tissues was subjected to microarray analysis to determine differential gene expression. At a statistical cutoff of p

Preeclampsia is a complication of pregnancy that is marked by hypertension, proteinuria, and maternal endothelial dysfunction. A central factor in the etiology of the disease is the development of placental hypoxia/ischemia, which releases pathogenic soluble factors. There is currently no effective treatment for preeclampsia, but the phosphodiesterase-5 (PDE-5) inhibitor sildenafil has been suggested, as PDE-5 is enriched in the uterus, and its antagonism could improve uteroplacental function. Here, we report in the reduced uterine perfusion pressure (RUPP) rat model that administration of oral sildenafil is effective in attenuating placental ischemia-induced hypertension during gestation. RUPP animals have significantly elevated arterial pressure compared with control animals (132 ± 3 vs. 100 ± 2 mmHg; P < 0.05). Administration of oral sildenafil (45 mg·kg−1·day−1) had no effect on blood pressure in control rats but decreased pressure in RUPP rats (115 ± 1 mmHg; P < 0.05). RUPP induced changes in placental sFlt-1, and vascular endothelial growth factor (VEGF) was unaffected by sildenafil administration, as was the decrease in free plasma VEGF. RUPP animals had a significant increase in medullary PDE-5/β-actin ratio (1 ± 0.14 vs. 1.63 ± 0.18; P < 0.05) expression with a resulting reduction in renal medullary cGMP (1.5 ± 0.15 vs. 0.99 ± 0.1 pmol/μg protein, P < 0.05) compared with controls. Although sildenafil had no effect on renal medullary cGMP in control animals, it significantly increased cGMP in RUPP animals (1.3 ± 0.1 pmol/μg protein; P < 0.05). These data suggest that sildenafil might provide an effective therapeutic option for the management of hypertension during preeclampsia.

Preeclampsia is a disorder characterized by new onset hypertension during pregnancy, as well as other clinical findings such as proteinuria and edema. This disorder affects approximately five percent of pregnancies and is the leading cause of maternal and fetal morbidity. Though the origins of the disease are unclear, it is thought that placental ischemia is central to its etiology. Commonly, the uterine spiral artery fails to adequately remodel to allow for adequate blood flow to the developing fetal/placental unit, causing hypoxia and ischemia. It is well established that hypoxia can lead to endoplasmic reticulum (ER) stress in cells. When ER stress occurs, protein misfolding occurs, leading to the unfolded protein response (UPR). One process which could be important in an attempt to restore cellular homeostasis is autophagy, a specialized process of carrying defective proteins to lysosomes for degradation to prevent aggregation from occurring. There are several factors which play a role in this process, and are utilized as a marker for autophagy, notably Beclin-1 and various autophagy related genes (Atg). Though autophagy has been examined previously in cancer and numerous cardiovascular abnormalities, it is unclear whether induction of autophagy is one of the cell survival pathways activated in response to placental ischemia. Here we have examined placental tissue from term pregnant rats and rats which have undergone placental ischemia due to the reduced uterine perfusion pressure (RUPP) procedure to to determine whether autophagy pathways have been activated as part of the cell survival response during chronic ischemia. As determined by western blot, protein levels of the autophagy markers beclin (57 ± 6 A.U. vs 113 ± 16 A.U., p

Purpose of review Vascular endothelial growth factors (VEGFs) influence renal function through angiogenesis, with VEGF-A being the most potent inducer of vascular formation. In the normal glomerulus, tight homeostatic balance is maintained between the levels of VEGF-A isoforms produced by podocyte cells, and the VEGF receptors (VEGFRs) expressed by glomerular endothelial, mesangial, and podocyte cells. Renal disease occurs when this homeostatic balance is lost, manifesting in the abnormal autocrine and paracrine VEGF-A/VEGFR signaling, ultrastructural glomerular and tubular damage, and impaired filtration. Recent findings Preclinical disease models of ischemic renal injury, including acute ischemia/reperfusion, thrombotic microangiopathy, and chronic renovascular disease, treated with exogenous VEGF supplementation demonstrated therapeutic efficacy. These results suggest a therapeutic VEGF-A paracrine effect on endothelial cells in the context of acute or chronic obstructive ischemia. Conversely, renal dysfunction in diabetic nephropathy appears to occur through an upregulated VEGF autocrine effect on podocyte cells, which is exacerbated by hyperglycemia. Therefore, VEGF supplementation therapy may be contraindicated for treatment of diabetic nephropathy, but specific results will depend on dose and on the specific site of VEGF delivery. A drug delivery system that demonstrates cell specificity for glomerular or peritubular capillaries could be employed to restore balance to VEGF-A/VEGFR2 signaling, and by doing so, prevent the progression to end-stage renal disease. Summary The review discusses the preclinical data available for VEGF supplementation therapy in models of renal disease.

One of the most pervasive disorders of pregnancy is preeclampsia, which is defined as new-onset hypertension presenting after the 20th week of gestation and is accompanied by increasing levels of proteinuria and often edema.1 The overall prevalence of preeclampsia is ≈8% with higher incidence in specific ethnic subpopulations, notably blacks.2,3 The disorder is predominantly a complication of primiparous women, who have a 3-fold higher incidence rate than multiparous women. There are a number of known factors that convey elevated risk of developing preeclampsia, notably elevated body mass index, and a previous incidence of preeclampsia, because women who experienced preeclampsia in previous pregnancies are 7 times more likely to exhibit preeclamptic symptoms in subsequent pregnancies than those with no history of preeclampsia.4 It has also been shown that high body mass index can double the risk of preeclampsia, and the scale of obesity correlates directly with the increase risk of developing the disorder.5 Although the link between these risk factors seem logical, there are also a number of other risk factors (maternal age, induced abortions, interpregnancy interval, and socioeconomic factors) for which the links to preeclampsia are not as clear.6 More research is warranted into the mechanistic effect of these factors in the etiology of preeclampsia. There are currently no definitive treatment options for the resolution of preeclampsia. Available interventions are confined to magnesium sulfate for the prophylaxis of seizures and the administration of one of various antihypertensive agents, although normalization of blood pressure is not normally possible, and the disease continues to progress.1 Indeed, the only effective resolution of preeclampsia is delivery of the placenta, because delivery of the fetus alone is not sufficient.7,8 It is this fact that suggested the pathological origins of the development of preeclampsia. Although …

During pregnancy, there are a number of important changes to cardiovascular function which are necessary for progression of a successful pregnancy. Additionally, preexisting cardiovascular conditions can be exacerbated by the adaptations that occur during gestation. These can present serious therapeutic challenges in the management of the cardiology patient during pregnancy. Significantly, the number of pregnant women at risk of cardiovascular complications is on the rise, so identification of risk factors that predict cardiac outcomes is essential to proper screening of the obstetrical patient. In diagnosed preexisting conditions, such as pulmonary hypertension, counseling is important prior to pregnancy. In the case of underlying disorders unmasked by pregnancy, or new-onset complications like preeclampsia, appropriate monitoring and treatment of the cardiovascular complications is warranted. Ultimately, collaborative care by both obstetricians and cardiologists is essential for the successful resolution of cardiovascular dysfunction in the obstetrical patient.

Preeclampsia is a pregnancy-induced hypertensive disorder characterized by proteinuria and widespread maternal endothelial dysfunction. It remains one of the most common disorders in pregnancy and remains one of the leading causes of maternal and fetal morbidity. Recent research has revealed that placental insufficiency, resulting in hypoxia and ischemia, is a central causative pathway in the development of the disorder. In response, the placenta secretes soluble substances into the maternal circulation which are responsible for the symptomatic phase of the disease. Among the most well characterized factors in the disease pathology are the anti-angiogenic protein soluble fms-like tyrosine kinase-1 (sFlt-1), inflammatory cytokines, and agonistic angiotensin II type-1 receptor autoantibodies. Each of these factors has been shown to induce hypertension experimentally through the production of endothelin-1 (ET-1), a powerful vasoconstrictor. Antagonism of the endothelin-A receptor has proved beneficial in numerous animal models of gestational hypertension, and it remains an intriguing target for pharmacological intervention in preeclampsia.

Introduction Preeclampsia (PE) is a multifactorial disease in which little progress has been made to develop adequate therapy. One of the etiologies of this maternal syndrome includes a rise in maternal anti-angiogenic factors; such as sFlt-1. Here we describe a novel therapeutic antagonist of sFlt-1 based on placental growth factor (PlGF). Hypothesis We hypothesize that our novel therapeutic, ELP-PlGF, will attenuate the hypertension and endothelial dysfunction in the preclinical RUPP model of placental insufficiency. Methods Animals were received on GD11 and received the sham or RUPP surgery on GD14 along with drug or vehicle administration. On GD18, carotid catheters were placed for blood pressure measurement on GD19. Western blots used serum samples with an antibody specific for PlGF (Abcam) and were normalized to the amount of serum loaded per well. Results Untreated HUVEC cells had significantly greater tube formation compared to cells treated with sFlt-1 (44.6 + 7.4 tubes/field vs 29.3 + 6.4 tubes/field, p + 4.3 tubes/field vs 44.6 + 7.4 tubes/field, p = 0.998). RUPP animals had significantly increased blood pressure compared to normal pregnant counterparts (116.7 + 1.96 mmHg vs 92.4 + 3.32 mmHg, p + 1.96 mmHg vs 105.6 + 4.70 mmHg, p = 0.051). Western blots showed a trend for decreased circulating PlGF (1.0 + 0.18 vs 0.73 + 0.11-fold change, p = 0.26, n = 4) in RUPP animals, with a near- significant trend towards increased endogenous free PlGF with ELP-PlGF administration (0.73 + 0.11 vs 1.79 + 0.35, p = 0.051, n = 4). Discussion Angiogenic imbalance is one of the best characterized contributors to the development of preeclampsia, largely lead by elevated sFlt-1. Our promising data suggest that our novel drug, ELP-PlGF, may work to correct this imbalance and potentially serve as a therapeutic for preeclampsia.

Pre-eclampsia is a hypertensive disorder of pregnancy initiated by placental insufficiency and chronic ischemia. In response, several pathways activated in the placenta are responsible for the maternal syndrome, including increased production of the anti-angiogenic protein, sFlt-1, and inflammatory cytokines, especially tumor necrosis factor-alpha (TNF-α). Previous studies have demonstrated that heme oxygenase (HO) induction can block TNF-α pathways in vitro and attenuate placental ischemia-induced sFlt-1 in vivo. Here, we investigated whether HO-1 induction could attenuate TNF-α-induced hypertension in pregnant rats. In response to TNF-α infusion (100 ng/day i.p.), maternal mean arterial pressure (MAP) increased vs. control animals (104 ± 3 vs. 119 ± 3 mmHg). HO-1 induction had no effect in control animals, but significantly decreased MAP in TNF-α-infused animals (108 ± 2 mmHg). Placental vascular endothelial growth factor (VEGF) was decreased in response to TNF-α infusion (92 ± 4 vs. 76 ± 2 pg/mg). Placental sFlt-1 was increased by TNF-α infusion (758 ± 45 vs. 936 ± 46 pg/mg, p < 0.05), which trended to normalization by HO-1 induction (779 ± 98 pg/mg). In contrast, HO-1 induction had no significant effect on placental VEGF in TNF-α-infused animals. Taken together, these data suggest that one of the key mechanisms by which HO exerts cytoprotective actions in the placenta during inflammation due to chronic ischemia is through suppression of sFlt-1. Further work elucidating the bioactive metabolites of HO-1 in innate inflammatory responses to placental ischemia is warranted.

Preeclampsia is a hypertensive disorder of pregnancy characterized by hypertension, proteinuria, and maternal endothelial dysfunction. While the underlying cause is still an active area of investig...

Evaluation of: Woods AK, Hoffmann DS, Weydert CJ et al. Adenoviral delivery of VEGF121 early in pregnancy prevents spontaneous development of preeclampsia in BPH/5 mice. Hypertension 57(1), 94–102 (2011).Preeclampsia is a pregnancy-specific hypertension characterized by proteinuria and maternal endothelial dysfunction. Recent research has focused on the balance of pro- and anti-angiogenic factors in the development of the disorder, specifically the proteins VEGF, PlGF, sFlt-1 and sEng. In a recent paper, Woods et al. demonstrated that administration of adenovirally delivered VEGF attenuates the pathological features of preeclampsia that are present in a novel murine model of the disorder, the BPH/5 mouse. This is a recent addition to a body of literature that suggests an important role for VEGF bioavailability in the maintenance of a healthy endothelium during pregnancy, and suggests an intriguing target for the development of new therapeutics for the treatment of preeclampsia.

Up-regulation of placental soluble fms-like tyrosine kinase 1 (sFlt1) contributes to the pathogenesis of preeclampsia. To evaluate novel upstream pathways that regulate placental sFlt1 production, we screened a library of natural compounds (n=502) in human placental cell lines. Here, we report 3 compounds in the cardiac glycoside family, ouabain, gitoxigenin, and digitoxin, that inhibit placental sFlt1 production at nanomolar concentrations in vitro. We further characterized ouabain and demonstrated that it inhibits sFlt1 mRNA and protein expression in human placental cytotrophoblasts and explant cultures in a dose- and time-dependent manner. Ouabain down-regulated sFlt1 production by inhibiting hypoxia-inducible factor 1 (HIF-1α) protein expression in the placenta. Furthermore, we found that phosphorylation of heat-shock protein 27 (HSP27) was necessary for ouabain to inhibit HIF-1α translation. In a rat model of pregnancy-induced hypertension, ouabain reduced mean arterial pressure and enhanced placental HSP27 phosphorylation without any adverse effects on pups. Further studies are needed to explore the usefulness of targeting HIF-1α/HSP27 pathway in preeclampsia.—Rana, S., Rajakumar, A., Geahchan, C., Salahuddin, S., Cerdeira, A. S., Burke, S. D., George, E. M., Granger, J. P., Karumanchi, S. A. Ouabain inhibits placental sFlt1 production by repressing HSP27-dependent HIF-1α pathway.

Preeclampsia is a serious complication of pregnancy marked by hypertension and maternal endothelial dysfunction. Recently we have published a series of studies demonstrating that induction of heme oxygenase-1 (HO-1) could attenuate many of the maternal symptoms of preeclampsia in a rodent model of placental ischemia induced by Reductions on Uterine Perfusion Pressure (RUPP). We have further shown that the individual metabolites of HO-1, namely CO and bilirubin, both downregulate hypoxia-induced production of known placental derived pathogenic factors ex vivo. Here, we tested whether , administration of the CO-releasing molecule CORM-3 could attenuate the maternal symptoms of placental ischemia. In response to placental ischemia, rats exhibited marked increases in blood pressure compared to control animals (107 ± 1 vs 136 ± 2mmHg, p

Maintenance of blood pressure and vascular function during pregnancy is dependent on a carefully orchestrated program of placental development that adequately supplies the developing uteroplacental unit with blood.1 Failure to adequately remodel the uterine vasculature can lead to chronic placental ischemia, now recognized as a central causative agent in several pregnancy pathologies, most notably preeclampsia.2 In recent years, research from numerous labs has identified a number of pathogenic agents produced by the placenta in response to placental ischemia—the VEGF antagonist soluble fms-like tyrosine kinase-1 (sFlt-1) and oxidative stress being major activated targets.3–7 However, even under nonpathological conditions, the placenta is a remarkably hypoxic organ, and it is not entirely clear what intrinsic pathways are responsible for keeping these potentially pathogenic agents in check. There is emerging evidence, however, that these 2 factors can be negatively regulated by the heme oxygenase (HO) system.8,9 HO is commonly considered a housekeeping protein responsible for the degradation of heme released from the breakdown of heme-containing proteins. Heme, a powerful pro-oxidant, is converted by HO into biliverdin, releasing the bioactive molecule carbon monoxide (CO) in the process. Biliverdin is then rapidly converted to bilirubin by biliverdin reductase, and both biliverdin and bililrubin have been shown to have potent antioxidant properties.10,11 HO, and particularly the inducible isoform HO-1, has recently become a target of interest in several pathological states, perhaps most notably hypertension. HO-1 or its metabolites have demonstrated beneficial effects in the treatment of many forms of experimental hypertension, including AngII-dependent, pulmonary, and renovascular hypertension.12–14 Manipulation of the HO-1 system as a therapeutic remains an active area of research. sFlt-1 is perhaps the best-characterized factor released by the ischemic placenta and is a soluble form of the VEGF receptor Flt-1. In the soluble form, sFlt-1 binds free VEGF and makes it unavailable for normal signaling, thereby acting as a potent VEGF antagonist.15 Interestingly, sFlt-1 is also produced at significantly elevated levels by the placenta during even healthy pregnancies, but this is balanced out by a concomitant increase in the VEGF family member placental growth factor (PlGF).16 Preeclampsia then is the imbalanced increase in sFlt-1 in proportion to VEGF/PlGF, but what keeps these factors in balance during normal gestation remains obscure. Intriguingly, several recent reports have demonstrated that HO-1, CO, and bilirubin could negatively affect sFlt-1 production in response to various stimuli.8,9 Oxidative stress has also been intensively studied as a cause of hypertension in response to placental ischemia. Preeclamptic placentas exhibit significant elevations in oxidative stress, and in experimental placental ischemia–induced and sFlt-1–induced hypertension, inhibition of reactive oxygen leads to significant attenuation of the associated hypertension.3,17 Given the hypoxic nature of the healthy placenta, it is not clear how the organ keeps oxidative stress under control. Several recent reports have demonstrated that HO-1 is important for placental development. Crossing of heterozygous HO-1+/- animals leads to significant defects in placental vascular development and structure and placental morphology. This is associated with prevalent fetal demise of the homozygous offspring, lowered fetal weight, decreased litter size, and altered vascular structure and placental morphology regardless of fetal genotype.18,19 However the effects of HO-1 disruption on blood pressure regulation, angiogenic balance, and oxidative stress in late gestation have not been examined. In this study, we have investigated the effect of pharmacological HO inhibition on blood pressure, angiogenic balance, and oxidative stress in late gestation. We demonstrate that HO inhibition leads to an antiangiogenic shift in the placenta, increased placental oxidative stress, and subsequently increased maternal blood pressure.

Preeclampsia is a complication of pregnancy which is marked by hypertension, proteinuria, and maternal endothelial dysfunction. A central factor in the etiology of the disease is the development of...

Placental hypoxia/ischemia has been implicated as a central factor in the development of preeclampsia. One particularly useful animal model to study the impact of placental ischemia is the reduced uterine perfusion pressure (RUPP) model. We have previously demonstrated that RUPP animals exhibit elevated placental oxidative stress, which plays an important role in the development of the associated maternal hypertension. Recently, we have demonstrated that cobalt protoporphyrin (CoPP)-mediated induction of heme oxygenase-1 (HO-1) attenuates RUPP-induced oxidative stress and consequent hypertension. However, signaling pathways that are involved in this process are virtually unknown. Here, we show that placentas from RUPP animals exhibit increased phosphorylation of JNK, STAT1, STAT3, and p52shc with a concomitant increase in caspase-3 activation and depletion of intracellular ATP. Treatment with CoPP decreased RUPP-induced phosphorylation of JNK and STAT1, while it increased phosphorylation of ERK and STAT3, leading to decreased caspase-3 activation and restoration of intracellular ATP content. Our data imply that RUPP induces oxidative stress and the consequent injurious state by increasing phosphorylation of mediators of injury (STAT1, JNK) and, to a lesser extent, survival (STAT3, p52shc) in placentas of pregnant rats. HO-1 induction shifts this balance to a prosurvival phenotype by augmenting phosphorylation of the prosurvival ERK and STAT3, while suppressing phosphorylation of JNK and STAT1. This attenuates the resulting injury, as indicated by caspase-3 activation and ATP depletion. These results demonstrate a novel therapeutic activity of HO-1 induction in placental cell survival during ischemia and support the HO-1 pathway as a promising therapeutic target for the management of preeclampsia.

Preeclampsia is a leading cause of maternal and fetal morbidity during pregnancy, affecting ~5–10% of all pregnancies. Classical hallmarks of the disorder include de novo hypertension, proteinuria, and marked edema, and at present the only effective treatment for the disorder is early delivery of the fetus. In normal gestation, the mother experiences increased cardiac output and fluid volume, while total vascular resistance, renal vascular resistance, vascular reactivity, and arterial pressure show marked decreases. This is in contrast to preeclampsia, in which vascular resistance, pressor response to vasoconstrictors, and arterial pressure are all increased. Recent evidence suggests that these hemodynamic changes are secondary to factors released from the placenta in response to hypoxia and ischemia seen during preeclampsia. This chapter highlights the mechanisms involved and discusses the effects of placental ischemia on the vasculature of the preeclamptic patient.

One potential mechanism contributing to the increased risk for encephalopathies in women with preeclampsia is altered cerebral vascular autoregulation resulting from impaired myogenic tone. Whether placental ischemia, a commonly proposed initiator of preeclampsia, alters cerebral vascular function is unknown. This study tested the hypothesis that placental ischemia in pregnant rats (caused by reduced uterine perfusion pressure [RUPP]) leads to impaired myogenic responses in middle cerebral arteries. Mean arterial pressure was increased by RUPP (135±3 mm Hg) compared with normal pregnant rats (103±2 mm Hg) and nonpregnant controls (116±1 mm Hg). Middle cerebral arteries from rats euthanized on gestation day 19 were assessed in a pressure arteriograph under active (+Ca 2+ ) and passive (0 Ca 2+ ) conditions, whereas luminal pressure was varied between 25 and 150 mm Hg. The slope of the relationship between tone and pressure in the middle cerebral artery was 0.08±0.01 in control rats and was similar in normal pregnant rats (0.05±0.01). In the RUPP model of placental ischemia, this relationship was markedly reduced (slope=0.01±0.00; P P

Background The renal medullary endothelin (ET-1) system plays an important role in the control of sodium excretion and arterial pressure (AP) through the activation of renal medullary ET-B receptors. We have previously shown that blockade of endothelin type B receptors (ET-B) leads to salt-sensitive hypertension through mechanisms that are not fully understood. One possible mechanism is through a reduction in renal medullary production of 20-hydroxyeicosatetraenoic acid (20-HETE). 20-HETE, a metabolite of arachidonic acid, has natriuretic properties similar to ET-B activation. While these findings suggest a possible interaction between ET-B receptor activation and 20-HETE production, it is unknown whether blockade of medullary ET-B receptors in rats maintained on a high sodium intake leads to reductions in 20-HETE production. Methodology/Principal Findings The effect of increasing sodium intake from low (NS = .8%) to high (HS = 8%) on renal medullary production of 20-HETE in the presence and absence of renal medullary ET-B receptor antagonism was examined. Renal medullary blockade of ET-B receptors resulted in salt sensitive hypertension. In control rats, blood pressure rose from 112.8±2.4 mmHg (NS) to 120.7±9.3 mmHg (HS). In contrast, when treated with an ET-B receptor blocker, blood pressure was significantly elevated from 123.7±3.2 (NS) to 164.2±7.1 (HS). Furthermore, increasing sodium intake was associated with elevated medullary 20-HETE (5.6±.8 in NS vs. 14.3±3.7 pg/mg in HS), an effect that was completely abolished by renal medullary ET-B receptor blockade (4.9±.8 for NS and 4.5±.6 pg/mg for HS). Finally, the hypertensive response to intramedullary ET-B receptor blockade was blunted in rats pretreated with a specific 20-HETE synthesis inhibitor. Conclusion These data suggest that increases in renal medullary production of 20-HETE associated with elevating salt intake may be, in part, due to ET-B receptor activation within the renal medulla.

Preeclampsia (PE) is one of the leading causes of fetal and maternal morbidity, affecting 5–10% of all pregnancies, and lacks an effective treatment. The exact etiology of the disorder is unclear, but placental ischemia has been shown to be a central causative agent. In response to placental ischemia, the antiangiogenic protein fms-like tyrosine kinase-1 (sFlt-1), a VEGF antagonist, and reactive oxygen species are secreted, leading to the maternal syndrome. One promising therapeutic approach to treat PE is through manipulation of the heme oxygenase-1 (HO-1) protein. It has been previously reported that HO-1 and carbon monoxide downregulate sFlt-1 production in vitro, and we have recently shown that HO-1 induction significantly attenuates placental ischemia-induced hypertension, partially through normalization of the sFlt-1-to-VEGF ratio in the placenta. The purpose of this study was to determine whether HO-1 induction would have beneficial effects independently of sFlt-1 suppression. To that end, pregnant rats were continuously infused with recombinant sFlt-1 from gestational days 14–19, and circulating sFlt-1 increased approximately twofold, similar to rats with experimentally induced placental ischemia. In response, mean arterial pressure increased 17 mmHg, which was completely normalized by HO-1 induction. Unbound circulating VEGF was decreased ∼17% in response to sFlt-1 infusion but was increased ∼50% in response to HO-1 induction. Finally, endothelial function was improved as measured by reductions in vascular expression of preproendothelin mRNA. In conclusion, manipulation of HO-1 presents an intriguing therapeutic approach to the treatment of PE.

Although it is well established that the renal endothelin (ET-1) system plays an important role in regulating sodium excretion and blood pressure through activation of renal medullary ETBreceptors, the role of this system in Dahl salt-sensitive (DS) hypertension is unclear. The purpose of this study was to determine whether the DS rat has abnormalities in the renal medullary endothelin system when maintained on a high sodium intake. The data indicate that Dahl salt-resistant rats (DR) on a high-salt diet had a six-fold higher urinary endothelin excretion than in the DR rats with low Na+intake (17.8 ± 4 pg/day vs. 112 ± 44 pg/day). In sharp contrast, urinary endothelin levels increased only twofold in DS rats in response to a high Na+intake (13 ± 2 pg/day vs. 29.8 ± 5.5 pg/day). Medullary endothelin concentration in DS rats on a high-Na+diet was also significantly lower than DR rats on a high-Na+diet (31 ± 2.8 pg/mg vs. 70.9 ± 5 pg/mg). Furthermore, DS rats had a significant reduction in medullary ETBreceptor expression compared with DR rats while on a high-Na+diet. Finally, chronic infusion of ET-1 directly into the renal medulla blunted Dahl salt-sensitive hypertension. These data indicate that a decrease in medullary production of ET-1 in the DS rat could play an important role in the development of salt-sensitive hypertension observed in the DS rat.

Objective We sought to determine the effect of an endothelin type A receptor antagonist (ETA) on uterine artery resistive index (UARI) and mean arterial pressure (MAP) in a placental ischemia rat model of preeclampsia produced by reduction in uterine perfusion pressure (RUPP). Study Design UARI was assessed by Doppler velocimetry in RUPP and normal pregnant controls (NP) on gestational days (GD) 12, 15, and 18. UARI was also determined on GD 18 in NP and RUPP pregnant dams after pretreatment with ETA. MAP was recorded on GD 19. Results The RUPP group had a higher MAP and UARI on GD 15 and 18 than the NP group. Pretreatment with ETA attenuated both the MAP and GD-18 UARI in the RUPP group without affecting these parameters in the NP group. Conclusion The improvement in UARI could be one potential mechanism for the reduction in MAP in response to ETA in pregnant dams with ischemic placentas.

Recent in vitro studies have reported that heme oxygenase 1 (HO-1) downregulates the angiostatic protein soluble fms-like tyrosine kinase 1 from placental villous explants and that the HO-1 metabolites CO and bilirubin negatively regulate endothelin 1 and reactive oxygen species. Although soluble fms-like tyrosine kinase 1, endothelin 1, and reactive oxygen species have been implicated in the pathophysiology of hypertension during preeclampsia and in response to placental ischemia in pregnant rats, it is unknown whether chronic induction of HO-1 alters the hypertensive response to placental ischemia. The present study examined the hypothesis that HO-1 induction in a rat model of placental ischemia would beneficially affect blood pressure, angiogenic balance, superoxide, and endothelin 1 production in the ischemic placenta. To achieve this goal we examined the effects of cobalt protoporphyrin, an HO-1 inducer, in the reduced uterine perfusion pressure (RUPP) placental ischemia model and in normal pregnant rats. In response to RUPP treatment, mean arterial pressure increases 29 mm Hg (136±7 versus 106±5 mm Hg), which is significantly attenuated by cobalt protoporphyrin (118±5 mm Hg). Although RUPP treatment causes placental soluble fms-like tyrosine kinase 1/vascular endothelial growth factor ratios to alter significantly to an angiostatic balance (1.00±0.10 versus 1.27±0.20), treatment with cobalt protoporphyrin causes a significant shift in the ratio to an angiogenic balance (0.68±0.10). Placental superoxide increased in RUPP (952.5±278.8 versus 243.9±70.5 relative light units/min per milligram) but was significantly attenuated by HO-1 induction (482.7±117.4 relative light units/min per milligram). Also, the preproendothelin message was significantly increased in RUPP, which was prevented by cobalt protoporphyrin. These data indicate that HO-1, or its metabolites, is a potential therapeutic for the treatment of preeclampsia.

Conceptus-derived interferon-tau (IFN-tau) has been implicated in the process of maternal recognition of pregnancy in the bovine. This type I IFN interacts with a uterine receptor complex to elicit secondary maternal responses, one of which is secretion of uterine proteins. We investigated the effects of pregnancy and recombinant (r) bovine (bo) IFN-tau (10(7) antiviral units/mg) on secreted proteins by cultured bovine endometrial explants. Explants were cultured for 24 h with [3H]leucine and dialyzed medium analyzed by one- and two-dimensional SDS polyacrylamide gel electrophoresis (PAGE) and fluorography. In one-dimensional PAGE experiments, endometrium representing early pregnancy (days 16-21) and the estrous cycle (days 16-19) was cultured in the presence of 5 nM rboIFN-tau and showed an increase (two- to five-fold) in secretion of 12- and 28-kD proteins. Further examination of these proteins by using two-dimensional PAGE indicated that the 12-kD protein was basic (pIor = 7.5), whereas the 28-kD protein was acidic (pI approximately 5.0). Isoelectric focusing in the acidic range revealed that the 28-kD protein was composed of several isoelectric variants (pI 4.5-5.5). Although the functions of these secretory proteins are currently unknown, they serve as useful markers for IFN action and may act as secondary signals to protect the early developing conceptus.

The role of adenosine in the regulation of cardiovascular function has long been acknowledged, but only recently has its importance in angiogenesis been appreciated, most notably, through its direct regulation of the proangiogenic growth factor, VEGF. Recent work has established that proangiogenic and antiangiogenic factors, specifically VEGF and and the soluble VEGF receptor fms-like tyrosine kinase-1 (sFlt-1), are directly influenced by hypoxia in placental ischemia. While adenosine has been reported to be an important regulator of VEGF in vascular tissue, the importance of adenosine in regulating VEGF and sFlt-1 in placental tissue is unclear. Here, we have investigated the role of adenosine in the secretion of VEGF and the antiangiogenic protein sFlt-1 in placental villous explants. Under normoxic conditions (6% oxygen), the nonspecific adenosine receptor antagonist, 8-sulphophenyltheophylline (8-SPT) had no effect on either VEGF ( P = 0.38) or sFlt-1 ( P = 0.56) secretion. However, under hypoxic conditions (1% oxygen), 8-SPT attenuated the increase in the secretion of both VEGF and sFlt-1 ( P < 0.05 and P < 0.005, respectively). Exogenous and the adenosine transporter inhibitor dipyridamole (which increases extracellular levels of adenosine) showed differential effects under normoxic conditions: sFlt-1 levels in media increased significantly ( P < 0.05), whereas VEGF was unaffected ( P = 0.67 and P = 0.19, respectively). These data indicate that extracellular adenosine can regulate VEGF and sFlt-1 secretion in the hypoxic placenta and could, therefore, control the balance of these competing angiogenic factors in diseases characterized by placental ischemia.

Objectives Upregulation of placental soluble fms-like tyrosine kinase 1 (sFlt1) contributes to the pathogenesis of preeclampsia. Our aim was to evaluate novel upstream pathways that regulate placental sFlt1 production. Methods We screened a library of natural compounds ( N = 502) in primary cytotrophoblasts and placental villous cultures and characterized molecules that had biological activity in the nanomolar range. sFlt1 production was assayed by ELISA. Immunoblot analysis, Co-immunoprecipitation, RT-PCR were employed in Characterizing the sFlt1, HIF AND hsp27 proteins and RNA. Pregnancy-induced hypertension rats were used as animal models. Results Here we report three compounds in the cardiac glycoside family, ouabain, gitoxigenin and digitoxin that inhibited placental sFlt1 production at nanomolar concentrations in vitro. We further characterized ouabain and demonstrate that it inhibits sFlt1 mRNA and protein expression in human placental cytotrophoblasts and explant cultures in a dose and time dependent manner. Ouabain down-regulated sFlt1 production by inhibiting hypoxia inducible factor 1 (HIF-1 α ) protein expression in the placenta. Furthermore, we found that phosphorylation of heat shock protein 27 (HSP27) was necessary for ouabain to inhibit HIF-1 α translation. In a rat model of pregnancy-induced hypertension, ouabain reduced mean arterial pressure and enhanced placental HSP27 phosphorylation without any adverse effects on pups. Conclusions Collectively we show that ouabain inhibits placental sFlt1 production through a HIF-1 α / HSP27 dependent pathway. Further studies are needed to explore the usefulness of targeting HIF-1 α /HSP27 pathway in preeclampsia. Disclosures S. Rana: None. A. Rajakumar: None. C. Geahchan: None. S. Salahuddin: None. A. Cerdeira: None. S.D. Burke: None. E. George: None. J. Granger: None. S. Karumanchi: co-inventor on multiple patents for preeclampsia markers and reports service as a consultant to Siemens Diagnostics, and has financial interest in Aggamin LLC.

Background Therapeutic angiogenesis with vascular endothelial growth factor (VEGF), delivered either via recombinant protein infusion or via gene therapy, has shown promise in preclinical models of various diseases including myocardial infarction, renovascular disease, preeclampsia, and neurodegenerative disorders. However, dosing, duration of expression, and tissue specificity are challenges to VEGF gene therapy, and recombinant VEGF delivery suffers from extremely rapid plasma clearance, necessitating continuous infusion and/or direct injection at the site of interest. Methods Here we describe a novel growth factor purification and delivery system (PADS) generated by fusion of VEGF121 to a protein polymer based on Elastin-like Polypeptide (ELP). ELP is a thermally responsive biopolymer derived from a five amino acid repeat sequence found in human tropoelastin. VEGFPADS were constructed by fusion of the ELP coding sequence in-frame with the VEGF121 coding sequence connected by a flexible di-glycine linker. In vitro activity of VEGFPADS was determined using cell proliferation, tube formation, and migration assays with vascular endothelial cells. Pharmacokinetics and biodistribution of VEGFPADS in vivo were compared to free VEGF in mice using quantitative fluorescence techniques. Results ELP fusion allowed for recombinant expression and simple, non-chromatographic purification of the ELP-VEGF121 chimera in yields as high as 90 mg/L of culture and at very high purity. ELP fusion had no effect on the VEGF activity, as the VEGFPADS were equally potent as free VEGF121 in stimulating HUVEC proliferation, tube formation, and migration. Additionally, the VEGFPADS had a molecular weight five-fold larger than free VEGF121, which lead to slower plasma clearance and an altered biodistribution after systemic delivery in vivo. Conclusion PADS represent a new method of both purification and in vivo stabilization of recombinant growth factors. The use of this system could permit recombinant growth factors to become viable options for therapeutic angiogenesis in a number of disease models. Electronic supplementary material The online version of this article (doi:10.1186/s13221-014-0026-3) contains supplementary material, which is available to authorized users.