Human amniotic fluid stem cell-extracellular vesicles as paracrine candidates to rejuvenate cardiomyocyte renewal

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): University of Genova

Background

Reactivation of cardiomyocyte renewal represents a milestone for cardiac regeneration. While broadly active in the early neonatal mammalian myocardium, such mechanism is lost soon after birth, with transition to defective repair. We previously showed that human amniotic fluid stem cells (hAFS) possess cardioprotective and cardioactive paracrine potential in a preclinical adult mouse model of myocardial infarction (MI)1, by sustaining cardiomyocyte cell cycle re-entry up to DNA duplication.

Purpose

Here we analyse whether hAFS secretome formulations, namely hAFS-conditioned medium (hAFS-CM) over extracellular vesicles (hAFS-EVs) separated from that, can enhance cardiomyocyte renewal in vitro and in vivo.

Methods

hAFS were obtained by leftover samples of prenatal screening amniocentesis and primed under 1% O2 preconditioning to enrich hAFS-CM and hAFS-EVs with cardioactive factors. hAFS-EVs were concentrated from hAFS-CM by serial ultracentrifugation. hAFS-EVs were profiled by electron microscopy, nanoparticle tracking analysis, proteomics and RNA sequencing (RNAseq). Neonatal mouse ventricular cardiomyocytes (mNVCM) were enzymatically isolated from R26pFUCCI2 mice with fluorescent tagging of cell-cycle by nuclear signal (G1-phase by Cdt1-mCherry; S-G2-M-phases by Geminin-mVenus1)2. mNVCM were stimulated by hAFS-CM or hAFS-EVs to identify the most promising formulation for further analysis in a R26pFUCCI2 4-day-old MI mouse model via intra-peritoneal delivery, according to principles of laboratory animal care and in compliance with authorization from the Italian Ministry of Health.

Results

hAFS-EVs sustained R26pFUCCI2 mNVCM transition from S- to M-phase by 2.1-fold (*p<0.05) in vitro, while triggering cytokinesis by 4.5-fold (*p<0.05) increase by Aurora B kinase expression at midbodies. Treated mNVCM showed disorganized expression of cardiac α-actinin, suggesting cytoskeletal re-arrangements prior to cell renewal, with significant down-regulation (0.6-fold, ****p<0.0001) of Cofilin-2 (CFL-2) an actin cytoskeleton regulator antagonizing cardiomyocyte proliferation3. RNAseq on hAFS-EVs revealed some of the mostly enriched microRNAs (miRNAs) targeting CFL-2 (miR-93-5p; miR-152-3p; miR-200b-3p; miR-429; miR-199a-3p; miR-20a-5p; miR-425-5p), while proteomics reported enrichment of a secreted form of Agrin, an important mediator for neonatal heart regeneration4. hAFS-EVs increased cardiomyocyte S- to M phase transition by 1.8-fold (*p<0.05) in the mouse neonatal left ventricle 3 days post-MI.

Conclusions

Our current findings suggest that EVs secreted by developmentally juvenile hAFS may be endowed with relevant potential to support cardiomyocyte renewal for future paracrine therapy in regenerative medicine with putative molecular candidate(s) of action in their cargo content including Agrin and non-coding miRNAs.

Molecular and genomic analysis of genes encoding surface-anchored proteins from Clostridium difficile

The gene slpA, encoding the S-layer precursor protein in the virulent Clostridium difficile strains C253 and 79--685, was identified. The precursor protein carries a C-terminal highly conserved anchoring domain, similar to the one found in the Cwp66 adhesin (previously characterized in strain 79--685), an SLH domain, and a variable N-terminal domain mediating cell adherence. The genes encoding the S-layer precursor proteins and the Cwp66 adhesin are present in a genetic locus carrying 17 open reading frames, 11 of which encode a similar two-domain architecture, likely to include surface-anchored proteins.

Liquid chromatography/atmospheric pressure chemical ionization mass spectrometry of terpene lactones in plasma of volunteers dosed with Ginkgo biloba L. extracts

Liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI-ITMS) was applied to evaluate the levels of ginkgolides A and B and bilobalide in plasma of volunteers after administration of Ginkgo biloba extracts in free (Ginkgoselect) or phospholipid complex (Ginkgoselect Phytosome) forms, providing 9.6 mg of total terpene lactones. The maximum plasma concentrations, C(max), of total ginkgolides A, B and bilobalide were 85.0 and 181.8 microg/mL for Ginkgoselect and Ginkgoselect Phytosome, respectively. The C(max) values were reached at 120 min for the free form and at 180--240 min for the phospholipid complex form. In both cases, the mean elimination half-life of each terpene lactone was in the range 120--180 min. Due to its sensitivity (about 1 ng/mL) and specificity, LC/APCI-ITMS proved to be a very powerful tool for pharmacokinetic studies of these phytochemicals.

Electrospray characterization of selected medicinal plant extracts

Extracts of selected medicinal plants were examined by electrospray mass spectrometry (ESI-MS). This technique allowed identification of the main components of each extract, thereby providing a typical finger-print of the examined plants. More specifically, anthocyanins (Vaccinium myrtillus), isoflavones (Glycine max, soybean), flavonol-glycosides and terpenes (Ginkgo biloba), triterpenes (Centella asiatica), caffeoyl-quinic acids (Cynara scolymus, artichoke), ginsenosides (Panax ginseng), catechins (Camellia sinensis, green tea) and flavones and flavanones (Propolis) were detected rapidly at levels in the range of 0.1-1 microg/ml, using 0.2-1 mg/ml of each medicinal plant extract.

Electrospray ionization mass spectrometry of synthetic oligonucleotides using 2-propanol and spermidine

Oligonucleotides have become widely used tools in molecular biology and molecular diagnostics. Their parallel synthesis in large numbers and the increasing interest in microarray technology has raised the requirement for fast and informative analytical tools for their quality control. A direct injection electrospray ionization mass spectrometry (ESI-MS) technique based on the use of aqueous 2-propanol as running eluent, and spermidine (or triethylamine) as DNA modifiers, has been applied to analyze a large set of samples (about 200 synthetic oligonucleotides) ranging from 5 to 15 kDa (17-51mers) with good results in terms of sensitivity, suppression of sodium adduct formation, and speed of analysis. Copyright 2000 John Wiley & Sons, Ltd.

High performance liquid chromatography/electrospray mass spectrometry of Hypericum perforatum extracts

Hypericum perforatum L. (St. John's Wort) is a widely distributed herbaceous perennial plant which has been well known as a medicinal plant since antiquity. In recent years, H. perforatum has received increasing attention for the treatment of depression and other neuralgic disorders. The main constituents of H. perforatum extract include flavonoids, naphthodianthrones, phloroglucinols, essential oils and xanthones. The present work reports the analysis of naphthodianthrones and phloroglucinols in H. perforatum extracts by means of high performance liquid chromatography (HPLC) coupled simultaneously to a diode array detector (DAD) and electrospray mass spectrometry (ESI-MS). Hypericin, pseudohypericin, hyperforin and adhyperforin were separated and identified on the base of their on-line UV and mass spectra. Quantitative analysis of hypericin derivatives in different extracts of H. perforatum using DAD and MS detectors was performed. In addition, direct infusion ESI-MS of H. perforatum extracts was applied to obtain rapid mass fingerprints of constituents present in the sample.

Liquid chromatography/electrospray mass spectrometry of bioactive terpenoids in Ginkgo biloba L

Standardized extracts of Ginkgo biloba leaves are mainly used in the treatment of peripheral and celebral circulation disorders, and also as a remedy against asthma, coughs, bladder inflammation, blenorrhagia and alcohol abuse. The leaf extracts contain biflavones, flavonol glycosides and terpene lactones. This paper reports a method based on liquid chromatography coupled with electrospray mass spectrometry for the analysis of terpenoids in G. biloba extracts. This method allows the rapid isocratic separation of underivatized ginkgolides (GA, GB, GC and GJ) and bilobalide at very low levels (10 pg on the column) and their quantitative detection by external standardization with relative standard deviations of 3 and 5% for intra- and inter-day analyses, respectively.

MEKC analysis of different Echinacea species

The distribution pattern of caffeic acid derivatives in Echinacea species is complex, and problems with the identity of each drug have been recognized. Micellar electrokinetic chromatography (MEKC) has been applied to define the fingerprints of Echinacea angustifolia, Echinacea pallida, and Echinacea purpurea, and their mixtures. The results obtained evidence that MEKC is a valuable tool for the characterization of these drugs.

Transforming activity of the chimeric sequence formed by the fusion of collagen gene COL1A1 and the platelet derived growth factor b-chain gene in dermatofibrosarcoma protuberans

As a consequence of a reciprocal translocation t(17;22)(q22;q13) and of supernumerary ring chromosomes derived from the t(17;22), a fusion between the platelet-derived growth factor b-chain (PDGF, c-sis proto-oncogene) and the collagen type 1A1 (COL1A1) genes has been recently described in dermatofibrosarcoma protuberans (DP), an infiltrating skin tumor (Simon et al., 1997). Although PDGFB has been implicated in transforming processes via autocrine and paracrine pathways, by the activation of the cognate receptor, no direct evidence of its involvement in neoplastic transformation of human tumours has been so far provided. In this report, we have tested the DNA from four DPs in the classical DNA transfection assay onto NIH3T3 fibroblast cell line. All the DNAs induced the formation of transformed foci in the transfected cultures whose derived cell lines were shown to contain a fused sequence comprising the human COL1A1 and PDGF genes. The relative breakpoint regions have been sequenced revealing that this gene fusion deleted exon 1 of PDGF and released the growth factor from its normal regulation. All the biochemical and biological assays were consistent with the model of an autocrine mechanism for NIH3T3 transformation by the human rearranged PDGFB gene involving the activation of the endogenous PDGF receptor.

Analysis of Stevia glycosides by capillary electrophoresis

The determination of diterpene glycosides from Stevia rebaudiana leaves using capillary electrophoresis is described. Analyses were performed on fused silica capillaries with 20 mM sodium tetraborate buffer, pH 8.3, and 30 mM sodium dodecyl sulfate. The effect of the organic solvent injected with the sample solution on the electrophoretic solution has been confirmed, and an absolute amount of 1.6 nL per injected sample was optimal. Rebaudioside A and steviolbioside were isolated by semipreparative high performance liquid chromatography (HPLC), and their structure was assessed by mass spectrometry.

Echinacoside and caffeoyl conjugates protect collagen from free radical-induced degradation: a potential use of Echinacea extracts in the prevention of skin photodamage

The protective effect of caffeoyl derivatives (echinacoside, chlorogenic acid, chicoric acid, cynarine, and caffeic acid, typical constituents of Echinacea species) on the free radical-induced degradation of Type III collagen has been investigated. The macromolecule was exposed to a flux of oxygen radicals (superoxide anion and hydroxyl radical) generated by the xanthine/xanthine oxidase/Fe2+/EDTA system and its degradation assessed qualitatively by SDS-PAGE and quantitatively as the amount of soluble peptides (according to the 4-hydroxyproline method) released from native collagen after oxidative stress. The SDS-PAGE pattern of native collagen is markedly modified by free radical attack, with formation of a great number of peptide fragments with molecular masses below 97 kDa: in the presence of microM concentrations of echinacoside, there is a complete recovery of the native profile. Collagen degradation was, in fact, dose-dependently inhibited by all the compounds, with the following order of potency: echinacoside approximately chicoric acid > cynarine approximately caffeic acid > chlorogenic acid, with IC50 ranging from 15 to 90 microM. These results indicate that this representative class of polyphenols of Echinacea species protects collagen from free radical damage through a scavenging effect on reactive oxygen species and/or C-, N-, S-centered secondary radicals, and provide an indication for the topical use of extracts from Echinacea species for the prevention/treatment of photodamage of the skin by UVA/UVB radiation, in which oxidative stress plays a crucial role.

Influence of structure on the behavior of flavonoids in capillary electrophoresis

In an attempt to elucidate the relation between structure and electrophoretic behavior, the effect of pH, surfactant and buffer on electrophoretic mobilities and resolution of several flavonoids, differing in structure, has been investigated. Ring-B substitution and the presence of a free hydroxy group at C7 of ring A play an important role, whereas O-methoxylation is less significant. Glycosylation also contributes in determining different degrees of complexation with borate, thus affecting the mobilities.

Improved procedure for the preparation of DNA restriction fragments suitable for sequencing

A rapid and integrated procedure was developed for the preparation of small DNA restriction fragments (< or = 1000 bp) starting from a large cosmid (35,000 bp) containing exogenous DNA. The process is based on restriction enzymatic digestion followed by HPLC separation and fractions collection. All DNA fragments are separated in a single run, detected "on-line" by UV absorption, and straightforward collected with very high recovery. Small fragments can be directly subjected to the sequence procedure, whereas those larger than 1000 bp are redigested with a second enzyme, the fractionated subfragments are separated, ligated to plasmid vector, and sequenced. A human genomic cosmid of 35,000 bp (26H7) has been chosen as a model.

Proliferative activity in normal colon mucosa and tumor tissue: clinical implications

The study deals with the analysis of proliferative activity in colon carcinomas and adjacent normal appearing mucosa, evaluated with in vitro 3H-Thymidine and autoradiography. In the colonic mucosa no significant differences in 3H-Thymidine Labelling Index (TLI) were observed in relation to the distance of the sample from the neoplasia. The distribution of S-phase cells along the crypt length is low at the bottom, increases rapidly with a maximum within the lower 25% and decreases in the highest positions. When the proliferative activity is increased there is the possibility of expanding the proliferative compartment towards the luminal region of the crypt. The division of the crypt into 5 parts makes it possible to identify 2 different patterns: the first with a very high TLI in the lower fifth, then a sharp decrease and without labelled cells in the highest parts; the second with labelled cells present also in the luminal fifth. These 2 aspects are characteristic of specimens with the lowest and the highest TLI values respectively. The analysis of TLI in colo-rectal cancers shows that cell kinetics parameters are not related to clinical and histopathological features such as sex, age, Dukes and TNM stages and grade of differentiation.

Direct characterization of caffeoyl esters with antihyaluronidase activity in crude extracts from Echinacea angustifolia roots by fast atom bombardment tandem mass spectrometry

Fast atom bombardment (FAB-MS) and fast atom bombardment tandem mass spectrometry (FAB-MS/MS) techniques (negative ions) have been successfully applied for identification of the constituents responsible for the antihyaluronidase activity of Echinacea angustifolia roots, whose extracts are widely employed for the adjuvant therapy of chronic inflammatory diseases. Crude extracts from different solvents were tested for antihyaluronidase activity, and those with the greatest inhibitory action (the ethylacetate, butylacetate and chloroform fractions, IC50 0.44, 0.50 e 0.62 mg/ml) were directly analyzed by MS. Full scan mass spectra produced intense molecular anions: collisional activation of these resulted in tandem mass spectra rich in significant product ions. Four main caffeoyl conjugates were detected and identified by tandem mass spectrometry (daughter and parent ion mode): 2,3-O-dicaffeoyltartaric acid (chicoric acid) and 5-O-dicaffeoylquinic acid (cynarine) and 2-O-caffeoyltartaric acid (caffaric acid) in the ethylacetate fraction. Among these caffeoyl conjugates, chicoric and caftaric acids had the greatest antihyaluronidase activity: IC50 = 0.42 and 0.61 mM, while the IC50 of cynarine and chlorogenic acid were 1.85 and 2.25 mM.

Cell kinetics of melanocytes in common and dysplastic nevi and in primary and metastatic cutaneous melanoma

The 3H-thymidine labelling (LI) and mitotic (MI) indexes were calculated in 29 cutaneous melanocytic lesions: 6 common nevi (CN), 11 dysplastic nevi, subclassified as nevi with architectural atypia (NAA = 4) and nevi with cyto-architectural atypia (NCAA = 7), 2 melanomas in situ (MIS), 4 invasive superficial spreading melanomas (IM) and 6 metastatic melanomas (MM). The LI mean values resulted to be: CN = 0.23%, NAA = 0.98%, NCAA = 1.79%, MIS = 5.75%, IM = 5.16%, MM = 3.80%. In CN, NAA, NCAA and MIS, these values were calculated at epidermal level; in IM and MM at dermal level. At dermal level, the LI mean values of CN, NAA and NCAA were: 0.20%, 0.20%, 0.23% respectively. The MI mean value was close to 0 in CN, NAA, NCAA, MIS; 0.18% in IM, 0.16% in MM. Confirming a low proliferative activity in CN and a high activity in melanomas (MIS, IM, MM), the results showed that dysplastic nevi (NAA, NCAA) had a proliferative activity intermediate between common nevi and melanomas. The lesions with melanocytic atypia (NCAA) resulted to have a higher proliferative activity than those without this histological feature (NAA).

Separation of flavonol-2-O-glycosides from Calendula officinalis and Sambucus nigra by high-performance liquid and micellar electrokinetic capillary chromatography

Calendula officinalis and Sambucus nigra flowers were analysed by reversed-phase high-performance liquid chromatography (RP-HPLC) and micellar electrokinetic capillary chromatography (MECC). RP-HPLC was performed on C8 Aquapore RP 300 columns with eluents containing 2-propanol and tetrahydrofuran. MECC was carried out on a 72-cm fused-silica capillary using sodium dodecyl sulphate and sodium borate (pH 8.3) as the running buffer. The results obtained by these techniques are compared.

High-performance liquid chromatography determination of enzyme activities in the presence of small amounts of product

Enzymes can be assayed by HPLC by calculating the amount of substrate(s) left over, or product formed, through the peak area ratios with a suitable internal standard. However, sometimes the substrates used are contaminated with small amounts of products and this can lead to errors in the determination of the enzyme activity. A method for a HPLC test of such enzymes, which prevents eventual errors, uses the ratio substrate/product at time zero as internal standard and the kinetics can be followed with the aid of a simple mathematical equation. This approach was applied to the determination of the activities of papain, urokinase, NAD glycohydrolase, and pyruvate kinase samples and it was compared with the data obtained by the internal standard method, giving reproducible results in all cases.