Blood-Vessel-Inspired Hierarchical Trilayer Scaffolds: PCL/Gelatin-Driven Protein Adsorption and Cellular Interaction.

Fabrication of scaffolds with hierarchical structures exhibiting the blood vessel topological and biochemical features of the native extracellular matrix that maintain long-term patency remains a major challenge. Within this context, scaffold assembly using biodegradable synthetic polymers (BSPs) via electrospinning had led to soft-tissue-resembling microstructures that allow cell infiltration. However, BSPs fail to exhibit the sufficient surface reactivity, limiting protein adsorption and/or cell adhesion and jeopardizing the overall graft performance. Here, we present a methodology for the fabrication of three-layered polycaprolactone (PCL)-based tubular structures with biochemical cues to improve protein adsorption and cell adhesion. For this purpose, PCL was backbone-oxidized (O-PCL) and cast over a photolithography-manufactured microgrooved mold to obtain a bioactive surface as demonstrated using a protein adsorption assay (BSA), Fourier transform infrared spectroscopy (FTIR) and calorimetric analyses. Then, two layers of PCL:gelatin (75:25 and 95:5 w/w), obtained using a novel single-desolvation method, were electrospun over the casted O-PCL to mimic a vascular wall with a physicochemical gradient to guide cell adhesion. Furthermore, tensile properties were shown to withstand the physiological mechanical stresses and strains. In vitro characterization, using L929 mouse fibroblasts, demonstrated that the multilayered scaffold is a suitable platform for cell infiltration and proliferation from the innermost to the outermost layer as is needed for vascular wall regeneration. Our work holds promise as a strategy for the low-cost manufacture of next-generation polymer-based hierarchical scaffolds with high bioactivity and resemblance of ECM's microstructure to accurately guide cell attachment and proliferation.

Failure Analysis of TEVG's II: Late Failure and Entering the Regeneration Pathway.

Tissue-engineered vascular grafts (TEVGs) are a promising alternative to treat vascular disease under complex hemodynamic conditions. However, despite efforts from the tissue engineering and regenerative medicine fields, the interactions between the material and the biological and hemodynamic environment are still to be understood, and optimization of the rational design of vascular grafts is an open challenge. This is of special importance as TEVGs not only have to overcome the surgical requirements upon implantation, they also need to withhold the inflammatory response and sustain remodeling of the tissue. This work aims to analyze and evaluate the bio-molecular interactions and hemodynamic phenomena between blood components, cells and materials that have been reported to be related to the failure of the TEVGs during the regeneration process once the initial stages of preimplantation have been resolved, in order to tailor and refine the needed criteria for the optimal design of TEVGs.

Computational Characterization of Mechanical, Hemodynamic, and Surface Interaction Conditions: Role of Protein Adsorption on the Regenerative Response of TEVGs.

Currently available small diameter vascular grafts (<6 mm) present several long-term limitations, which has prevented their full clinical implementation. Computational modeling and simulation emerge as tools to study and optimize the rational design of small diameter tissue engineered vascular grafts (TEVG). This study aims to model the correlation between mechanical-hemodynamic-biochemical variables on protein adsorption over TEVG and their regenerative potential. To understand mechanical-hemodynamic variables, two-way Fluid-Structure Interaction (FSI) computational models of novel TEVGs were developed in ANSYS Fluent 2019R3® and ANSYS Transient Structural® software. Experimental pulsatile pressure was included as an UDF into the models. TEVG mechanical properties were obtained from tensile strength tests, under the ISO7198:2016, for novel TEVGs. Subsequently, a kinetic model, linked to previously obtained velocity profiles, of the protein-surface interaction between albumin and fibrinogen, and the intima layer of the TEVGs, was implemented in COMSOL Multiphysics 5.3®. TEVG wall properties appear critical to understand flow and protein adsorption under hemodynamic stimuli. In addition, the kinetic model under flow conditions revealed that size and concentration are the main parameters to trigger protein adsorption on TEVGs. The computational models provide a robust platform to study multiparametrically the performance of TEVGs in terms of protein adsorption and their regenerative potential.

Expanding the structure-activity relationship of cytotoxic diphenyl macrocycles.

Twenty-four biaryl tetrapeptide macrocycles were synthesized as an extension of our previous work. Two groups of compounds were constructed for establishing a structure-activity relationship: one having an aromatic substituent at α-position of one exo-peptide and the other group with a variation in the size of the lipophilic chain. Compound 13t had the best cytotoxicity from all the compounds tested (in a panel of six human cancer cell lines) and low toxicity on one healthy cell line. The study identified the lipophilic chain as the main structural moiety for improving the biological activity, being the seven-carbon chain the optimal length. On the other hand, the aromatic rings at α-position did not enhance the cytotoxicity.

Failure Analysis of TEVG's I: Overcoming the Initial Stages of Blood Material Interaction and Stabilization of the Immune Response.

Vascular grafts (VG) are medical devices intended to replace the function of a diseased vessel. Current approaches use non-biodegradable materials that struggle to maintain patency under complex hemodynamic conditions. Even with the current advances in tissue engineering and regenerative medicine with the tissue engineered vascular grafts (TEVGs), the cellular response is not yet close to mimicking the biological function of native vessels, and the understanding of the interactions between cells from the blood and the vascular wall with the material in operative conditions is much needed. These interactions change over time after the implantation of the graft. Here we aim to analyze the current knowledge in bio-molecular interactions between blood components, cells and materials that lead either to an early failure or to the stabilization of the vascular graft before the wall regeneration begins.

Multicomponent synthesis and preliminary anti-inflammatory activity of lipophilic diphenylamines.

Non-Steroidal Anti-inflammatory Drugs (NSAIDs) are some of the most prescribed medications for pain but the incidence of adverse effects -especially during chronic treatment- points out the requirement of new analgesics. In this study, we showed an efficient two-steps synthesis of diphenylamine-containing dipeptides consisting of a multicomponent process followed by a Buchwald-Hartwig cross-coupling reaction. We prepared 16 diphenylamine derivatives and evaluated their in vivo anti-inflammatory activity through an ear edema model using 12-O-tetradecanoylpholbol-13-acetate. Furthermore, the toxicity of the more potent compounds in the Artemia salina model and their cell viability using murine RAW 264.7 cells is reported. The fluorinated compound 10k becomes a reliable candidate since it reduced the TPA-induced edema to 92%, lacked cytotoxicity against murine macrophages, and had minimal toxicity in Artemia salina.

EC359: A First-in-Class Small-Molecule Inhibitor for Targeting Oncogenic LIFR Signaling in Triple-Negative Breast Cancer.

Leukemia inhibitory factor receptor (LIFR) and its ligand LIF play a critical role in cancer progression, metastasis, stem cell maintenance, and therapy resistance. Here, we describe a rationally designed first-in-class inhibitor of LIFR, EC359, which directly interacts with LIFR to effectively block LIF/LIFR interactions. EC359 treatment exhibits antiproliferative effects, reduces invasiveness and stemness, and promotes apoptosis in triple-negative breast cancer (TNBC) cell lines. The activity of EC359 is dependent on LIF and LIFR expression, and treatment with EC359 attenuated the activation of LIF/LIFR-driven pathways, including STAT3, mTOR, and AKT. Concomitantly, EC359 was also effective in blocking signaling by other LIFR ligands (CTF1, CNTF, and OSM) that interact at LIF/LIFR interface. EC359 significantly reduced tumor progression in TNBC xenografts and patient-derived xenografts (PDX), and reduced proliferation in patient-derived primary TNBC explants. EC359 exhibits distinct pharmacologic advantages, including oral bioavailability, and in vivo stability. Collectively, these data support EC359 as a novel targeted therapeutic that inhibits LIFR oncogenic signaling.See related commentary by Shi et al., p. 1337.

Recent Progress in Natural-Product-Inspired Programs Aimed To Address Antibiotic Resistance and Tolerance.

Bacteria utilize multiple mechanisms that enable them to gain or acquire resistance to antibiotic therapies during the treatment of infections. In addition, bacteria form biofilms which are surface-attached communities of enriched populations containing persister cells encased within a protective extracellular matrix of biomolecules, leading to chronic and recurring antibiotic-tolerant infections. Antibiotic resistance and tolerance are major global problems that require innovative therapeutic strategies to address the challenges associated with pathogenic bacteria. Historically, natural products have played a critical role in bringing new therapies to the clinic to treat life-threatening bacterial infections. This Perspective provides an overview of antibiotic resistance and tolerance and highlights recent advances (chemistry, biology, drug discovery, and development) from various research programs involved in the discovery of new antibacterial agents inspired by a diverse series of natural product antibiotics.

Utilizing cell line-derived organoids to evaluate the efficacy of a novel LIFR-inhibitor, EC359 in targeting pancreatic tumor stroma.

Survival of pancreatic cancer (PC) patient is poor due to lack of effective treatment modalities, which is partly due to the presence of dense desmoplasia that impedes the delivery of chemotherapeutics. Therefore, PC stroma-targeting therapies are expected to improve the efficacy of chemotherapeutics. However, in vitro evaluation of stromal-targeted therapies requires a culture system which includes components of both tumor stroma and parenchyma. We aim to generate a cell line-derived 3D organoids to test the efficacy of stromal-targeted, LIFR-inhibitor EC359. Murine PC (FC1245) and stellate (ImPaSC) cells were cultured to generate organoids that recapitulated the histological organization of PC with the formation of ducts by epithelial cells surrounded by activated fibroblasts, as indicated by CK19 and α-SMA staining, respectively. Analysis by qRT-PCR demonstrated a significant downregulation of markers of activated stroma, POSTN, FN1, MMP9, and SPARC (p<0.0001), when treated with gemcitabine in combination with EC359. Concurrently, collagen proteins including COL1A1, COL1A2, COL3A1, and COL5A1 were significantly downregulated (p <0.0001) after treatment with gemcitabine in combination with EC359. Overall, our study demonstrates the utility of cell lines-derived 3D organoids to evaluate the efficacy of stroma-targeted therapies as well as the potential of EC359 to target activated stroma in PC.

Synthesis of diphenylamine macrocycles and their anti-inflammatory effects.

A collection of fourteen diphenylamine macrocyclic derivatives containing a peptide chain with different substituents was synthesized using a protocol of two Ugi four component reactions (Ugi-4CR) and a Buchwald-Hartwig macrocyclization. Their anti-inflammatory effects were assayed with an ear edema model using 12-O-tetradecanoylphorbol-13-acetate, while the activity of myeloperoxidase was determined to evaluate the index of leukocyte infiltration. Compound 5e had an ID50 of 0.18 µM per ear with a potency higher than that of the reference drugs indomethacin and celecoxib (0.24 and 0.91 µM per ear, respectively). Moreover, the cytotoxicity of the macrocycles was determined in two healthy cell lines, showing a low percentage of toxicity.

A Two-Step Multicomponent Synthetic Approach and Anti-inflammatory Evaluation of N-Substituted 2-Oxopyrazines.

Inflammation is widely reported as a main factor for the development of chronic diseases such as cancer, diabetes, and even metabolic syndrome. Thus, the search for novel anti-inflammatory compounds is required. Herein we describe the synthesis of a collection of peptidic pyrazinones by a convenient approach involving a multicomponent isocyanide-based reaction followed by a tandem deprotection/oxidative cyclization step. This series of compounds were tested for their potential anti-inflammatory capacity in an in vivo murine model, and four compounds were identified to inhibit tetradecanoylphorbol acetate (TPA)-induced edema by more than 75 %. The two most active compounds, N-benzyl-2-(4-hydroxy-3,5-dimethoxyphenyl)-2-[2-oxopyrazin-1(2H)-yl]acetamide (10 o) and N-cyclohexyl-2-[2-oxopyrazin-1(2H)-yl]-2-[4-(trifluoromethyl)phenyl]acetamide (10 x), with methyl and trifluoromethyl groups, were also able to decrease myeloperoxidase activity and leukocyte infiltration. Moreover, 10 x decreased the thickness of TPA-treated mouse ears, as observed in histological analysis of the tissues.

Cytotoxic Activity and Structure-Activity Relationship of Triazole-Containing Bis(Aryl Ether) Macrocycles.

Cancer continues to be a worldwide health problem. Certain macrocyclic molecules have become attractive therapeutic alternatives for this disease because of their efficacy and, frequently, their novel mechanisms of action. Herein, we report the synthesis of a series of 20-, 21-, and 22-membered macrocycles containing triazole and bis(aryl ether) moieties. The compounds were prepared by a multicomponent approach from readily available commercial substrates. Notably, some of the compounds displayed interesting cytotoxicity against cancer (PC-3) and breast (MCF-7) cell lines, especially those bearing an aliphatic or a trifluoromethyl substituent on the N-phenyl moiety (IC50 <13 µm). Additionally, some of the compounds were able to induce apoptosis relative to the solvent control; in particular, (Z)-N-cyclohexyl-7-oxo-6-[4-(trifluoromethyl)phenyl]-11 H-3,10-dioxa-6-aza-1(4,1)-triazola-4(1,3),9(1,4)-dibenzenacyclotridecaphane-5-carboxamide (12 f) was the most potent in this regard (22.7 % of apoptosis).

Synthesis and cytotoxic effect of pregnenolone derivatives with one or two α,ß-unsaturated carbonyls and an ester moiety at C-21 or C-3.

Four series of pregnenolone derivatives having one or two α,ß-unsaturated carbonyls and an ester moiety at C-21 or C-3 were synthetized to compare their cytotoxicity effect. The final compounds were evaluated on three human cancer cell lines: PC-3 (prostate cancer), MCF-7 (breast cancer), SKLU-1 (lung cancer) and a noncancerous cell line HGF (human gingival fibroblast). Two steroids with a 4-fluorinated benzoic acid ester at C-21 were the most active against lung cancer cell line with IC50 of 13.1 ±â€¯1.2 and 12.8 ±â€¯0.5 µM and showed a low percentage of cytotoxicity for noncancerous cells (27.63 ±â€¯2.3 and 18.39 ±â€¯1.2% in the screening at 50 µM).

Diversity-oriented synthesis and cytotoxic activity evaluation of biaryl-containing macrocycles.

Synthesis of biaryl-containing macrocycles has been carried out through a four-step approach comprising two Ugi four component reactions and a Suzuki-Miyaura macrocyclization. This protocol allowed the synthesis of 12- and 14-membered macrocycles. Cytotoxic activity evaluation showed that some of the molecules were effective against leukemia, glioblastoma and lung cancer cell lines (IC50 = 4.0, 5.9 and 7.6, respectively).

Synthesis and Identification of Pregnenolone Derivatives as Inhibitors of Isozymes of 5α-Reductase.

Hyperplasia of the prostate gland and prostate cancer have been associated with high levels of serum 5α-dihydrotestosterone. This steroid is formed from testosterone by the activity of the enzyme 5α-reductase (5α-R) present in the prostate. Thus, inhibition of this enzyme could be a goal for therapies to treat these diseases. This study reports the synthesis and effects of five different 21-esters of pregnenolone derivatives as inhibitors of 5α-R types 1 and 2. The activity of these steroidal compounds was determined using in vivo and in vitro experiments. The results indicate that of the five steroids studied, the 21(p-fluoro)benzoyloxypregna-4,16-diene-3,6,20-trione derivative, whose structure has not yet been reported, has the best molecular conformation to inhibit the in vitro activity of both types of 5α-R. In addition, this steroid also displayed activity in vivo. Apparently, its pharmacological effect was increased by the presence of a keto group at C-6, because this group decreased the possibility that the steroid would be metabolized by hepatic enzymes. In addition, the double bond present at C-4 of this compound also enhanced its inhibitory activity on 5α-R, and the C-21 ester moiety increased its liphophilicity. Therefore, its solubility in the cell membrane and its pharmacological activity were both increased.

A new approach towards the synthesis of drospirenone and steroidal spirolactones.

A general methodology for the synthesis of different steroidal 17-spirolactones is described. This method uses lithium acetylide of ethyl propiolate as the three carbon synthon and the method was successfully applied for the process development of drospirenone.

Effect of two antiandrogens as protectors of prostate and brain in a Huntington's animal model.

The purpose of this work is to know the effect of flutamide and a novel synthetic steroid 3ß-p-Iodobenzoyloxypregnan-4,16- diene-6,20-dione (IBP) on the levels of dopamine, 5-HIAA (5-hydroxyindole acetic acid), and some oxidative stress markers in animal model with Huntington disease. Thirty male Wistar rats divided in groups of 6 animals each were subjected to the following treatment: group A, 3-nitro propionic acid (3-NPA, as inducer of Huntington); group B, flutamide; group C, 3-NPA + flutamide; group D, IBP; and group E, 3-NPA + IBP. Treatment scheme for all groups were at 4 mg/kg/day administered intraperitoneally. The measurement of haemoglobin was carried out from blood while the concentrations of ATPase, 5α-reductase, reduced glutathione (GSH), calcium, H2O2, 5-HIAA, and dopamine were determined from brain and prostate tissues using validated methods. The results depicted a significant decrease of dopamine and GSH in cerebellum/Medulla oblongata of animals treated with IBP. The prostate gland of the same group of treatment also showed a significant decrease in the concentrations of TBARS, H2O2, and total ATPase. In hemispheres of groups D and E, dopamine, H2O2, and total ATPase decreased significantly while in prostate, hemispheres, and cerebellum/Medulla oblongata of groups B and C; calcium, 5α-reductase, ATPase, H2O2, and TBARS were found to witness a significant decrease. Results showed an antiandrogenic activity of flutamide, while the novel steroid IBP showed neuroprotective properties by changes on oxidative stress biomarkers as critical pathways leading to prostate and brain degeneration. Probably steroid homeostasis disequilibrium could have led to alterations in dopamine metabolism GSH in Huntington's disease animal models.

Synthesis and cytotoxic effect on cancer cell lines and macrophages of novel progesterone derivatives having an ester or a carbamate function at C-3 and C-17.

In this study we report the cytotoxic effect on human cancer cells of two series of novel progesterone derivatives; the first containing an aromatic ester (8a-e) or a carbamate functions both linked to C-3 (9a-e) on the pregn-4,16-diene-6,20-dione skeleton. In the second series, both functional groups (ester and carbamate) are bound to C-17 on the pregn-4,6-diene-3,20-dione scaffold (13a-e and 14a-e). The panel cancer cell lines used in this study were the following: PC-3 (human prostate cancer cell line), MCF-7 (human breast cancer cell line), HCT-15 (human colon cancer cell line) and J774 (noncancerous murine macrophages) for comparison. The results from this study showed that steroid 14a, having a carbamate function at C-17, was the most potent against PC-3 cell line (96.6%) while 8c and 8e showed much higher cytotoxic activity (100%) for MCF-7 cell line. Finally, compounds 8c and 14a displayed selective properties towards tumor cell lines than noncancerous murine macrophages.

Aminochrome as a preclinical experimental model to study degeneration of dopaminergic neurons in Parkinson's disease.

Four decades after L-dopa introduction to PD therapy, the cause of Parkinson's disease (PD) remains unknown despite the intensive research and the discovery of a number of gene mutations and deletions in the pathogenesis of familial PD. Different model neurotoxins have been used as preclinical experimental models to study the neurodegenerative process in PD, such as 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and rotenone. The lack of success in identifying the molecular mechanism for the degenerative process in PD opens the question whether the current preclinical experimental models are suitable to understand the degeneration of neuromelanin-containing dopaminergic neurons in PD. We propose aminochrome as a model neurotoxin to study the neurodegenerative processes occurring in neuromelanin-containing dopaminergic neurons in PD. Aminochrome is an endogenous compound formed during dopamine oxidation and it is the precursor of neuromelanin, a substance whose formation is a normal process in mesencephalic dopaminergic neurons. However, aminochrome itself can induce neurotoxicity under certain aberrant conditions such as (i) one-electron reduction of aminochrome catalyzed by flavoenzymes to leukoaminochrome o-semiquinone radical, which is a highly reactive neurotoxin; or (ii) the formation of aminochrome adducts with alpha-synuclein, enhancing and stabilizing the formation of neurotoxic protofibrils. These two neurotoxic pathways of aminochrome are prevented by DT-diaphorase, an enzyme that effectively reduces aminochrome with two-electrons preventing both aminochrome one-electron reduction or formation alpha synuclein protofibrils. We propose to use aminochrome as a preclinical experimental model to study the neurodegenerative process of neuromelanin containing dopaminergic neurons in PD.