Comparison of double-filtration plasmapheresis (DFPP) versus heparin-mediated extracorporeal LDL-precipitation (HELP)-apheresis in early-onset preeclampsia

OBJECTIVES

Preeclampsia (PE) is a major cause of maternal and fetal mortality, and preterm birth. Previous studies indicate that lipid-apheresis may prolong pregnancy, namely heparin-mediated extracorporeal LDL-precipitation (HELP)- and dextran sulfate cellulose (DSC)-apheresis. We now report on double membrane plasmapheresis (DFPP) in early-onset preeclampsia (eoPE).

STUDY DESIGN

Open pilot study assessing the prolongation of pregnancy in PE by lipoprotein-apheresis (DRKS00004527). Two women with eoPE were treated by DFPP and compared to a historical cohort of 6 patients with eoPE treated by HELP-apheresis (NCT01967355).

MAIN OUTCOME MEASURES

Clinical outcome of mothers and babies and prolongation of pregnancies (time of admission to birth).

RESULTS

Patient 1 (33y; 22 + 5/7GW) received 4 DFPP. Delivery day 19; birthweight 270 g; weight at discharge 2134 g on day 132. Patient 2 (35y; 21 + 4/7GW) received 2 DFPP. Delivery day 19; birthweight 465 g; weight at discharge 2540 g on day 104. DFPP was well tolerated by both patients.

CONCLUSIONS

DFPP proved to be save and pregnancies remained stable as long as 19 days. Although babies were born very preterm both babies could finally be dismissed from hospital. No relevant clinical differences between DFPP and HELP-apheresis could be observed. Therefore, DFPP may extend the range of available apheresis techniques to prolong pregnancies in early-onset preeclampsia. However, further studies are necessary to gain more information. REGISTER: (DRKS00004527).

On the validity of fluorimetric intracellular calcium detection: Impact of lipid components

We investigated the effects of different lipids on the activity of the angiotensin II type 1 receptor (AT1R). As calcium plays a key role in the signaling of the AT1R, we used the calcium-sensitive fluorescence indicators fura-2 to detect intracellular calcium release upon stimulation with the agonist angiotensin II. At first sight, cells preincubated with Very low-density lipoprotein (VLDL) showed a reduced calcium release triggered by angiontensin II compared to untreated control. However, on closer examination, this result seemed to be an artifact. Incubation with VLDL reduced also the amount of intracellular fura-2, as measured by fluorescence in the isosbestic point. Additionally, the maximal obtainable ratio, obtained after complete saturation with calcium ions, was reduced in cells preincubated with VLDL. These findings rendered our initial results questionable. We report the results of our work and our suggestions regarding the experimental setup to contribute to the understanding of the interpretation of fura-2 measurements and to avoid erroneous conclusions.

Reversible Shielding and Immobilization of Liposomes and Viral Vectors by Tailored Antibody-Ligand Interactions

Controlling the time and dose of nanoparticulate drug delivery by administration of small molecule drugs holds promise for efficient and safer therapies. This study describes a versatile approach of exploiting antibody-ligand interactions for the design of small molecule-responsive nanocarrier and nanocomposite systems. For this purpose, antibody fragments (scFvs) specific for two distinct small molecule ligands are designed. Subsequently, the surface of nanoparticles (liposomes or adeno-associated viral vectors, AAVs) is modified with these ligands, serving as anchor points for scFv binding. By modifying the scFvs with polymer tails, they can act as a non-covalently bound shielding layer, which is recruited to the anchor points on the nanoparticle surface and prevents interactions with cultured mammalian cells. Administration of an excess of the respective ligand triggers competitive displacement of the shielding layer from the nanoparticle surface and restores nanoparticle-cell interactions. The same principle is applied for developing hydrogel depots that can release integrated AAVs or liposomes in response to small molecule ligands. The liberated nanoparticles subsequently deliver their cargoes to cells. In summary, the utilization of different antibody-ligand interactions, different nanoparticles, and different release systems validates the versatility of the design concept described herein.

A cohort-based emergency plan to maintain functionality in a clinical laboratory during the 2020 COVID-19 epidemic outbreak

Objectives

Clinical laboratory analyses are essential part of critical care. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)/coronavirus disease 2019 (COVID-19)-confirmed cases were doubling in Germany every 3 days during March 2020. Health care systems are preparing for an epidemic crisis.

Methods

We outline a cohort-based emergency planning. The plan is based on three independent self-sufficient cohorts that maintain duty for 7 days, followed by quarantine-like rest for 14 days. COVID-19-infected and otherwise ill personnel will be replaced by a tactical reserve, which is again replaced by recovered staff.

Results

We switched to the outlined system when incidence of confirmed COVID-19 cases surpassed 50/100,000 residents. Our parameter spectrum was reduced to the essential analyses in agreement with our clinical colleagues. So far the system works well. In model calculations, the system is robust to maintain essential laboratory functionality even when incidence of COVID-19 is higher than that currently observed in the most severely hit countries.

Conclusions

We outline a cohort-based emergency planning to maintain essential functionality of a clinical laboratory while minimizing the risk of spreading infection with COVID-19 among our workforce during the COVID-19 epidemic faced in 2020.

Apheresis as emerging treatment option in severe early onset preeclampsia

Based on an early suggestion by Winkler et al. 2003 and a subsequent successful study by Wang et al. 2006 using lipid apheresis (LA) in 9 patients with preeclampsia to prolong pregnancies, the use of apheresis as therapeutic option in severe early onset preeclampsia has received increasing attention. Further studies using different LA systems also prolonged pregnancy and have been published in the last few years. Albeit using different LA systems and relying on different working hypothesis, all studies demonstrated a promising stabilisation against the disease's progression. Overall time from hospitalisation to the need for mandatory delivery was longer for those patients receiving apheresis compared to historical or matched control patients not receiving apheresis. These data will be reviewed and different hypotheses about the beneficial mechanism of action of apheresis will be discussed. Since up to now there is no curative treatment for preeclampsia other than observation and delivery, future work shall be encouraged.

Treatment of very preterm preeclampsia via heparin-mediated extracorporeal LDL-precipitation (H.E.L.P.) apheresis: The Freiburg preeclampsia H.E.L.P.-Apheresis study

OBJECTIVE

Soluble Fms-like tyrosine kinase-1 (sFlt-1) is thought to be causative in the pathogenesis of preeclampsia (PE) and specific removal of sFlt-1 via dextran sulfate cellulose (DSC)-apheresis was suggested as cure to allow prolongation of pregnancy in preterm PE. However, in addition a deranged lipoprotein metabolism may impact endothelial and placental function in PE. Lipoprotein-apheresis by heparin-mediated extracorporeal LDL-precipitation (H.E.L.P.) was previously applied and has been shown to alleviate symptoms in PE. This clinical trial reevaluates the clinical efficacy of H.E.L.P.-apheresis in PE considering sFlt-1.

STUDY DESIGN

Open pilot study assessing the prolongation by H.E.L.P.-apheresis in 6 women (30-41 years) with very preterm PE (24+4 to 27+0 gestational weeks (GW)) (NCT01967355) compared to a historic control-group matched for GW at admission (<28 GW; n = 6). Clinical outcome of mothers and babies, and pre- and post H.E.L.P.-apheresis levels of sFlt-1 and PlGF were monitored.

MAIN OUTCOME MEASURES

In apheresis patients (2-6 treatments), average time from admission to birth was 15.0 days (6.3 days in controls; p = 0.027). Lung maturation was induced in all treated cases, and all children were released in healthy condition. Apheresis reduced triglycerides and LDL-cholesterol by more than 40%. Although H.E.L.P.-apheresis induced a transient peak baseline levels did not change and rather stabilized sFlt-1 levels at pre-apheresis levels throughout treatments, with sFlt-1/PLGF ratio remaining unaffected.

CONCLUSIONS

H.E.L.P.-apheresis proved again to be safe and prolongs pregnancies in PE. However, without changing sFlt-1 levels below baseline lowering lipids or other yet undefined factors appear to be of more relevance than reducing sFlt-1.

Lipoprotein turnover and possible remnant accumulation in preeclampsia: insights from the Freiburg Preeclampsia H.E.L.P.-apheresis study

Background

Preeclampsia is a life-threatening disease in pregnancy, and its complex pathomechanisms are poorly understood. In preeclampsia, lipid metabolism is substantially altered. In late onset preeclampsia, remnant removal disease like lipoprotein profiles have been observed. Lipid apheresis is currently being explored as a possible therapeutic approach to prolong preeclamptic pregnancies. Here, apheresis-induced changes in serum lipid parameters are analyzed in detail and their implications for preeclamptic lipid metabolism are discussed.

Methods

In the Freiburg H.E.L.P.-Apheresis Study, 6 early onset preeclamptic patients underwent repeated apheresis treatments. Serum lipids pre- and post-apheresis and during lipid rebound were analyzed in depth via ultracentrifugation to yield lipoprotein subclasses.

Results

The net elimination of Apolipoprotein B and plasma lipids was lower than theoretically expected. Lipids returned to previous pre-apheresis levels before the next apheresis even though apheresis was repeated within 2.9 ± 1.2 days. Apparent fractional catabolic rates and synthetic rates were substantially elevated, with fractional catabolic rates for Apolipoprotein B / LDL-cholesterol being 0.7 ± 0.3 / 0.4 ± 0.2 [day^− 1] and synthetic rates being 26 ± 8 / 17 ± 8 [mg*kg^− 1*day^− 1]. The distribution of LDL-subclasses after apheresis shifted to larger buoyant LDL, while intermediate-density lipoprotein-levels remained unaffected, supporting the notion of an underlying remnant removal disorder in preeclampsia.

Conclusion

Lipid metabolism seems to be highly accelerated in preeclampsia, likely outbalancing remnant removal mechanisms. Since cholesterol-rich lipoprotein remnants are able to accumulate in the vessel wall, remnant lipoproteins may contribute to the severe endothelial dysfunction observed in preeclampsia.

Trial registration

ClinicalTrails.gov, NCT01967355.

Systemic confounders affecting serum measurements of omega-3 and -6 polyunsaturated fatty acids in patients with retinal disease

Background

Omega-3 polyunsaturated fatty acids (PUFAs) have a highly anti-angiogenic effect in animal models. However, the clinical relevance of omega-3PUFAs in human retinal pathologies remains unclear. The ARED 2 study found no effect of omega-3 PUFA supplementation on progression of age related macular degeneration (AMD). The aim of this study was to compare serum levels of omega-3- and omega-6 PUFAs between patients with diabetic retinopathy (DR), AMD and retinal vein occlusion (RVO), and to identify potential confounders of serum level measurements.

Methods

Venous blood samples were collected from 44 patients with DR, 25 with AMD, 12 with RVO and 27 controls. The lipid phase was extracted and analyzed using mass spectrometry. Retinal disease staging was done by indirect funduscopy and FAG where appropriate. Patient demographics and medical history including current medication and fasting state were acquired. Tukey contrasts for multiple comparisons of the mean and linear regression analysis were used for statistical analysis.

Results

Our data revealed no significant differences in omega-6 PUFA serum levels between patients with AMD, DR, RVO and controls (p > 0.858). Uncorrected omega-3 PUFA levels were significantly higher in patients with AMD compared to DR but not compared to controls (p = 0.004). However, after correcting for possible confounders such as body mass index (BMI), age, sex, fasting and use of statins, no statistically significant difference remained for serum omega-3 PUFA levels. Fasting was identified as an independent confounder of total omega-6 PUFAs, three individual omega-6 PUFAs and one omega-3 PUFA(p < 0.0427). Statin use was identified as an independent confounder of α-linolenic acid (an omega-3PUFA; p = 0.0210).

Conclusion

In this pilot study with relatively low patient numbers, we report significant differences in serum levels of omega-3PUFAs among patients with different types of retinal diseases. However, these differences were not robust for disease specificity after correction for possible confounders in our cohort. Our results demonstrate that serum lipid profiles need to be interpreted with caution since they are significantly altered by variables like fasting and medication use independent from the underlying disease. Correcting for respective confounders is thus necessary to compare serum lipid profiles in clinical studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-016-0335-9) contains supplementary material, which is available to authorized users.

Accumulating nanoparticles by EPR: A route of no return

Nanoparticle-based drug delivery to ease anticancer therapy relies primarily on the enhanced permeability and retention effect (EPR). The leaky vascular structure in tumors allows extravasation of nanoparticles, often termed passive targeting. Long term retention of nanoparticles is attributed to the lack of lymphatic drainage, and unidirectional extravasation has been implied. Fluorescent liposomes with a plasma half-life of 29h were injected into tumor-bearing rats, and biodistribution in tumor, skin, paws and ears was monitored via in vivo fluorescence measurements. To calculate tissue accumulation, an algorithm was developed to subtract the blood signal from the total fluorescence recorded. Accumulation in tumor tissue was much higher than that in other tissues monitored, initially exhibiting very rapid accumulation followed by a long plateau phase with little change. Discontinuous plasmapheresis was established that was as effective as highly sophisticated clinical plasmapheresis. We observed no difference in the tumor tissue's accumulation when plasmapheresis was performed 22h after liposome injection. In contrast, plasmapheresis led to a significant inhibition of further accumulation in other tissues. When the liposomes' blood concentration was rapidly lowered, we detected no drop in tumor fluorescence. Thus extravasation via EPR is most likely a route of no return. These data support the emerging view of a more dynamic model of EPR, where gaps or entire vessels may open and close over time, or accumulated liposomes become entangled within the pores, hampering further accumulation.

Interference of phosphatidylcholines with in-vitro cell proliferation - no flock without black sheep

According to early experiments with natural extracts, phosphatidylcholines (PCs) are widely considered essentially non-toxic. In addition to these physiological mixed-chain PCs, many different synthetic diacyl-PCs are currently available, but they have never been systematically evaluated for any interference with cell proliferation. We thus investigated the cell proliferation of several cell lines in the presence of various liposomes consisting of a single PC component and cholesterol. Most of the PCs investigated did not interfere with cell proliferation, supporting the notion that most PCs are safe excipients. Significant IC50 values below 0.5mM were detected for PC(12:0/12:0), PC(14:1/14:1)trans and all diacyl-PCs containing two polyunsaturated fatty acids (PUFAs). The ω-3 PC(22:6/22:6) was the most toxic PC assessed, revealing IC50 values below 100 μM, but no rule concerning ω-3/6 configuration or acyl chain length could be observed. Physiological mixed-chain PCs containing PUFAs were much less toxic than respective non-physiological diacyl-PCs. All trans fatty acids in diacyl-PCs interfered more with proliferation than their respective cis-configured counterparts. Depending on the concentration, those diacyl-PCs not only inhibited proliferation but also induced cell death. Unlike the non-toxic PCs usually used for liposomal drug delivery, the elucidated diacyl-PCs may be worthy of further examination to eventually construct a toxic shell for toxic drugs, thereby enhancing anticancer drug delivery via lipid particles.

Kinetic targeting of pegylated liposomal doxorubicin: a new approach to reduce toxicity during chemotherapy (CARL-trial)

BACKGROUND

The therapeutic success of chemotherapeutic agents is often limited by severe adverse effects. To reduce toxicity of these drugs, nanoscale particle-based drug delivery systems (DDS) are used. DDS accumulate to some extent in tumor tissues, but only a very small portion of a given dose reaches this target. Accumulation of DDS in tumor tissues is supposed to be much faster than in certain other tissues in which side effects occur ("Kinetic Targeting"). Once saturation in tumor tissue is achieved, most of the administered DDS still circulate in the plasma. The extracorporeal elimination of these circulating nanoparticles would probably reduce toxicity.

METHODS

For the CARL-trial (Controlled Application and Removal of Liposomal chemotherapeutics), pegylated liposomal doxorubicin (PLD) was used as chemotherapeutic agent and double filtration plasmapheresis (DFPP) was performed for extracorporeal elimination of liposomes. PLD was given as 40 mg/m2 every 3 weeks in combination with vinorelbine 2 × 25 mg/m2 (neoadjuvant treatment of breast cancer, 12 patients), or as 40 mg/m2 every 4 weeks (recurrent ovarian cancer, 3 patients). Primary endpoints were the efficiency and safety profile of DFPP, and secondary endpoints were side effects and tumor response.

RESULTS

DFPP eliminated ~62% of circulating PLD, corresponding to ~45% of the total dose (n = 57 cycles). AUC of doxorubicin was reduced by 50%. No leakage of doxorubicin was detected during elimination, and no relevant DFPP-related side effects occurred. Reduction in tumor size > 30% occurred in 10/12 (neoadjuvant) and in 1/3 patients (recurrent). Only five grade 2 events and one grade 3 event (mucositis, neutropenia or leucopenia) and a single palmar-plantar erythrodysesthesia grade 2 were reported.

CONCLUSION

Extracorporeal elimination of PLD by DFPP is safe and efficient. CARL can diminish the main dose-limiting side effects of PLD, and probably many different DDS alike.

TRIAL REGISTRATION

DRKS00000163.

Fluvastatin/fenofibrate vs. simvastatin/ezetimibe in patients with metabolic syndrome: different effects on LDL-profiles

BACKGROUND

Patients with metabolic syndrome (MS) and type 2 diabetes (T2DM) show increased risk for coronary artery disease. Lipoprotein metabolism is characterized by elevated triglycerides (TG), low high-density lipoprotein cholesterol (HDL-C) and predominance of atherogenic small, dense low-density lipoprotein (sdLDL), while low-density lipoprotein (LDL) cholesterol is only slightly elevated.

METHODS

Multicentre, randomized, open-label cross-over study investigating the effect of combination of fluvastatin/fenofibrate (80/200 mg) (F&F) on LDL-subfractions compared with combination of simvastatin/ezetimibe (20/10 mg) (S&E) in patients with MS/T2DM.

RESULTS

Seventy-five patients were randomized, 69 completed the study and LDL-subfractions of 56 patients were analysed. Thirty-eight out of 56 patients (68%) showed a profile dominated by sdLDL. In these, TG and total cholesterol (TC) were elevated compared with non-sdLDL patients. In all patients, reduction of TC and LDL cholesterol (LDL-C) by S&E was stronger than by F&F. The increase of HDL-C was stronger with S&E in the non-sdLDL group, whereas in the sdLDL group, there was no difference between treatments. In non-sdLDL patients, there was no effect on TG or LDL-radius. However, in the sdLDL group, F&F was more effective in reducing TG and increased LDL radius, whereas S&E reduced LDL radius even further.

CONCLUSIONS

S&E is more efficient in reducing TC and LDL-C. This is also true for HDL-C increase in non-sdLDL patients. However, in patients with sdLDL, F&F was more efficient in reducing TG and increasing LDL radius.

Controlled application and scheduled removal of nanoparticle based chemotherapeutics (CARL) will reduce dose limiting adverse events in anticancer chemotherapy

Clinical success of cancer chemotherapy is impaired by dose limiting toxicities. Nanoscale particle based drug delivery systems (DDS) like long circulating liposomes show improved toxicity profiles. Nevertheless, their unique pharmacokinetic properties lead to new dose limiting adverse events such as elevated skin toxicity. Though DDS accumulate in tumor tissue, only a very small fraction of the total dose reaches the target site. The overwhelming amount of a given dose is needed only to build up a diffusion gradient for effective accumulation at the target site. Due to the altered endothelial barrier, accumulation of DDS in tumor tissue is much faster than accumulation in other tissues, where dose limiting side effects occur. On the basis of these pharmakinetic data we hypothesize, that once accumulation in the tumor tissue is completed, rapid elimination of the DDS fraction still circulating in the plasma may diminish otherwise dose limiting toxicities. Rapid elimination of circulating DDS might be performed by extracorporeal apheresis treatment. Within this paper the principle of kinetic targeting by scheduled extracorporeal elimination of long circulating DDS is presented in detail. Benefits for patients are as well discussed as possible criticisms and future developments. In conclusion, the combination of DDS and scheduled apheresis may allow the development of new chemotherapy regiments with higher impact and/or less toxicity.

Elimination of liposomes by different separation principles used in low-density lipoprotein apheresis

Clinical success of many therapies is impaired by dose limiting toxicities. Nanoscale particle-based drug delivery systems such as liposomes show unique pharmacokinetic properties and improved toxicity profiles. Liposomes accumulate in tumor tissue, but only a small fraction of a total dose reaches the target site. The overwhelming amount of a given dose is needed only to build up a diffusion gradient for effective accumulation at the target site. In order to find a way to detoxify this predominant fraction after accumulation is completed, the different separation principles used for the apheresis of lipoproteins were evaluated for the extracorporeal elimination of liposomes. Appropriate radiolabeled model liposomes were prepared by extrusion. Separation efficacy, leakage of liposomal content and influence of plasma contact were measured. Membranes with pore sizes between 25 and 400 nm were used to investigate filtration properties of liposomes. Liposomes were precipitated by adding heparin and Ca(2+). Adsorption chromatography was investigated using dextran sulfate, heparin sepharose and functionalized polyacrylamide beads. Membrane filtration allowed the elimination of various liposomes, while precipitation and adsorption were only useful for positively charged liposomes. Leakage of liposomal content was not induced by adsorption, but precipitation induced leakage. Leakage during filtration was dependent on liposomal membrane lipids. Plasma contact reduced precipitation and adsorption efficacy of positively charged liposomes, while filtration properties of liposomes remained unchanged. For extracorporeal elimination of liposomal drug delivery systems, filtration-based techniques are presumably more convenient and versatile than precipitation- or adsorption-based apheresis technologies.

Synthesis of phospholipid-conjugated bile salts and interaction of bile salt-coated liposomes with cultured hepatocytes

To examine the possibility of targeting liposomes to hepatocytes via bile salts, the bile salt lithocholyltaurine was covalently linked to a phospholipid. The isomeric compounds disodium 3alpha-(2-(1,2-O-distearoyl-sn-glycero-3-phospho-2'-ethanolamidosuccinyloxy)ethoxy)-5beta-cholan-24-oyl-2'-aminoethansulfonate and disodium 3beta-(2-(1,2-O-distearoyl-sn-glycero-3-phospho-2'-ethanolamidosuccinyloxy)ethoxy-5beta-cholan-24-oyl-2'-aminoethansulfonate (DSPE-3beta-LCT) were synthesized and incorporated into liposomal membranes. Confocal laser scanning microscopy studies showed that bile salt-bearing liposomes (BSLs) attach to the surface of rat hepatocytes in culture. Studies with radioactively labeled liposomes revealed that the bile salt linked via the 3beta-conformation resulted in a higher attachment efficiency than that with the 3alpha-derivative. In the presence of BSLs corresponding to 2 mM liposomal phosphatidylcholine, uptake of 50 microM cholyltaurine (CT) into hepatocytes was reduced by approximately 40% by the 3beta-derivative and by approximately 17% by the 3alpha-derivative. When added simultaneously with the liposomes, CT up to 75 microM inhibited the binding of DSPE-3beta-LCT-bearing liposomes. By contrast, increasing concentrations reversed this inhibition and resulted in an increased bile salt-mediated binding. The same was true when CT was added 10 min before the liposomes were added. The attachment of BSLs to the surface of hepatocytes opens up promising possibilities for hepatocyte-specific drug delivery. More generally, not only substrates for cellular endocytosing receptors but also substrates for cellular carrier proteins should be suitable ligands for the cell-specific targeting of nanoscale particles such as liposomes.