Ioannis S. Vizirianakis

Erythropoiesis: Model systems, molecular regulators, and developmental programs

Human erythropoiesis is a complex multistep developmental process that begins at the level of pluripotent hematopoietic stem cells (HSCs) at bone marrow microenvironment (HSCs niche) and terminates with the production of erythrocytes (RBCs). This review covers the basic and contemporary aspects of erythropoiesis. These include the: (a) cell‐lineage restricted pathways of differentiation originated from HSCs and going downward toward the blood cell development; (b) model systems employed to study erythropoiesis in culture (erythroleukemia cell lines and embryonic stem cells) and in vivo (knockout animals: avian, mice, zebrafish, and xenopus); (c) key regulators of erythropoiesis (iron, hypoxia, stress, and growth factors); (d) signaling pathways operating at hematopoietic stem cell niche for homeostatic regulation of self renewal (SCF/c‐kit receptor, Wnt, Notch, and Hox) and for erythroid differentiation (HIF and EpoR). Furthermore, this review presents the mechanisms through which transcriptional factors (GATA‐1, FOG‐1, TAL‐1/SCL/MO2/Ldb1/E2A, EKLF, Gfi‐1b, and BCL11A) and miRNAs regulate gene pattern expression during erythroid differentiation. New insights regarding the transcriptional regulation of α‐ and β‐globin gene clusters were also presented. Emphasis was also given on (i) the developmental program of erythropoiesis, which consists of commitment to terminal erythroid maturation and hemoglobin production, (two closely coordinated events of erythropoieis) and (ii) the capacity of human embryonic and umbilical cord blood (UCB) stem cells to differentiate and produce RBCs in culture with highly selective media. These most recent developments will eventually permit customized red blood cell production needed for transfusion.

Nanomedicine and personalized medicine toward the application of pharmacotyping in clinical practice to improve drug-delivery outcomes

UNLABELLED Recent technological advances in nanomedicine and nanotechnology in parallel with knowledge accumulated from the clinical translation of disease- and drug-related genomic data have created fertile ground for personalized medicine to emerge as the new direction in diagnosis and drug therapy. To this end, the development of sophisticated nano-based systems for targeted drug delivery, along with the advent of pharmacogenomics, moves the drug-prescription process toward pharmacotyping, e.g., the individualized adjustment of drug selection and dosage. However, the clinical validity and utility of pharmacogenomic testing must be demonstrated by cost-effectiveness analysis and establishment of clinical-practice reimbursement codes. Within this framework, and to achieve major benefits for all patients worldwide, a multidisciplinary scientific and technological infrastructure has to be organized in the healthcare system to address better the issues affecting regulatory environment, clinical pharmacology guidelines, education, bioethics and genomics data dissemination. FROM THE CLINICAL EDITOR Individualized pharmacotyping, patient and disease-specific delivery of drugs, combining nanotechnology and pharmagenomics-based approaches would result in much more specific and efficient treatment of a variety of illnesses. While this clearly is one of the main cornerstones of individualized medicine; the cost effective integration of this complex technology is far from trivial, as discussed in details in this opinion paper.

Controlled release of 5-fluorouracil from microporous zeolites.

UNLABELLED Zeolite particles with different pore diameter and particle size were loaded with the model anticancer drug 5-fluorouracil. The loaded zeolites were characterized by means of SEM, XRD, DSC, XPS, N2 physisorption and FT-IR. Higher loading of 5-FU was observed for NaX-FAU than BEA. Release studies were carried out in HCl 0.1N. Release of 5-FU from NaX-FAU showed exponential-type behaviour with the drug fully released within 10 min. In the case of BEA, the kinetics of 5-FU shows a multi-step profile with prolonged release over time. Molecular dynamics simulations showed that diffusion of the drug molecule through the BEA framework is lower than for NaX-FAU due to increased van der Waals interaction between the drug and the framework. The effect of zeolitic particles on the viability of Caco-2 monolayers showed that the NaX-FAU particles cause a reduction of cell viability in a more pronounced way compared with the BEA particles. FROM THE CLINICAL EDITOR This article describes zeolite-based nanoparticles in generating time-controlled release of 5-FU from zeolite preparations for anti-cancer therapy.

Pharmaceutical education in the wake of genomic technologies for drug development and personalized medicine.

The development of safe and effective new therapeutics is a long, difficult, and expensive process. Over the last 20-30 years, recombinant DNA (rDNA) technology has provided a multiple of new methods, molecular targets and DNA-based diagnostics to pharmaceutical research that can be utilized in assays for screening and developing potential biopharmaceutical drugs. In parallel, new innovative approaches to drug delivery systems were discovered and reached the market. Pharmaceutical biotechnology, pharmacogenomics, combinatorial chemistry, in close relation to high-throughput screening technologies, and bioinformatics are major advances that give a new direction to pharmaceutical sciences. To meet with the needs of this new dynamic era of pharmaceutical research and health care environment, pharmaceutical education has to set new priorities to keep pace with the challenges related to genomic technologies. The development of new initiative education programs, for both undergraduate and graduate curricula, in pharmacy has to be focused on preparing pharmacists oriented for both pharmacy practice and drug research and development. This can be achieved by providing future pharmacists with knowledge, skills and attitudes to be more competitive in the health care system, pharmacy practice-related fields, pharmaceutical industry and drug research and development areas, or finally in academia. Educators and pharmacy school members have the responsibility of deciding how, to what extent, by which methods, and/or in which way these changes and new directions in the education programs should be developed.

Lipid-like Self-Assembling Peptide Nanovesicles for Drug Delivery

Amphiphilic self-assembling peptides are functional materials, which, depending on the amino acid sequence, the peptide length, and the physicochemical conditions, form a variety of nanostructures including nanovesicles, nanotubes, and nanovalves. We designed lipid-like peptides with an aspartic acid or lysine hydrophilic head and a hydrophobic tail composed of six alanines (i.e., ac-A6K-CONH2, KA6-CONH2, ac-A6D-COOH, and DA6-COOH). The resulting novel peptides have a length similar to biological lipids and form nanovesicles at physiological conditions. AFM microscopy and light scattering analyses of the positively charged lipid-like ac-A6K-CONH2, KA6-CONH2 peptide formulations showed individual nanovesicles. The negatively charged ac-A6D-COOH and DA6-COOH peptides self-assembled into nanovesicles that formed clusters that upon drying were organized into necklace-like formations of nanovesicles. Encapsulation of probe molecules and release studies through the peptide bilayer suggest that peptide nanovesicles may be good candidates for sustained release of pharmaceutically active hydrophilic and hydrophobic compounds. Lipid-like peptide nanovesicles represent a paradigm shifting system that may complement liposomes for the delivery of diagnostic and therapeutic agents.

Lipid-like self-assembling peptide nanovesicles for drug delivery.

Amphiphilic self-assembling peptides are functional materials, which, depending on the amino acid sequence, the peptide length, and the physicochemical conditions, form a variety of nanostructures including nanovesicles, nanotubes, and nanovalves. We designed lipid-like peptides with an aspartic acid or lysine hydrophilic head and a hydrophobic tail composed of six alanines (i.e., ac-A6K-CONH2, KA6-CONH2, ac-A6D-COOH, and DA6-COOH). The resulting novel peptides have a length similar to biological lipids and form nanovesicles at physiological conditions. AFM microscopy and light scattering analyses of the positively charged lipid-like ac-A6K-CONH2, KA6-CONH2 peptide formulations showed individual nanovesicles. The negatively charged ac-A6D-COOH and DA6-COOH peptides self-assembled into nanovesicles that formed clusters that upon drying were organized into necklace-like formations of nanovesicles. Encapsulation of probe molecules and release studies through the peptide bilayer suggest that peptide nanovesicles may be good candidates for sustained release of pharmaceutically active hydrophilic and hydrophobic compounds. Lipid-like peptide nanovesicles represent a paradigm shifting system that may complement liposomes for the delivery of diagnostic and therapeutic agents.

Development of a nanoporous and multilayer drug-delivery platform for medical implants.

Biodegradable polymers can be applied to a variety of implants for controlled and local drug delivery. The aim of this study is to develop a biodegradable and nanoporous polymeric platform for a wide spectrum of drug-eluting implants with special focus on stent-coating applications. It was synthesized by poly(DL-lactide-co-glycolide) (PLGA 65:35, PLGA 75:25) and polycaprolactone (PCL) in a multilayer configuration by means of a spin-coating technique. The antiplatelet drug dipyridamole was loaded into the surface nanopores of the platform. Surface characterization was made by atomic force microscopy (AFM) and spectroscopic ellipsometry (SE). Platelet adhesion and drug-release kinetic studies were then carried out. The study revealed that the multilayer films are highly nanoporous, whereas the single layers of PLGA are atomically smooth and spherulites are formed in PCL. Their nanoporosity (pore diameter, depth, density, surface roughness) can be tailored by tuning the growth parameters (eg, spinning speed, polymer concentration), essential for drug-delivery performance. The origin of pore formation may be attributed to the phase separation of polymer blends via the spinodal decomposition mechanism. SE studies revealed the structural characteristics, film thickness, and optical properties even of the single layers in the triple-layer construct, providing substantial information for drug loading and complement AFM findings. Platelet adhesion studies showed that the dipyridamole-loaded coatings inhibit platelet aggregation that is a prerequisite for clotting. Finally, the films exhibited sustained release profiles of dipyridamole over 70 days. These results indicate that the current multilayer phase therapeutic approach constitutes an effective drug-delivery platform for drug-eluting implants and especially for cardiovascular stent applications.

Development of new drug delivery system based on ordered mesoporous carbons: characterisation and cytocompatibility studies

Ordered mesoporous carbons that encapsulate the poorly soluble compounds ibuprofen and indomethacin were systematically studied by means of X-ray diffraction (XRD), differential scanning calorimetry (DSC) and X-ray photon electron spectroscopy (XPS). The results showed marked differences in the release profiles of the two drug molecules in simulated gastric fluids. In vitro toxicity profiles appear to be compatible with potential therapeutic applications bringing them to the forefront as carriers of poorly water soluble drugs.

Synthesis, biological activity, and evaluation of the mode of action of novel antitubercular benzofurobenzopyrans substituted on A ring.

The 8-, 9-, 10-, and 11-halo, hydroxy, and methoxy derivatives of the antimycobacterial 3,3-dimethyl-3H-benzofuro[3,2-f][1]benzopyran were synthesized by condensation of the diazonium salts of 2-chloroanilines (13-17) with 1,4-benzoquinone (18), reduction of the intermediate phenylbenzoquinones 19-22 to dihydroxybiphenyls, cyclisation to halo-2-hydroxydibenzofurans 24-27, and construction of the pyran ring by thermal rearrangement of the corresponding dimethylpropargyl ethers 35-38. Palladium catalyzed nucleophilic aromatic substitution permitted conversion of the halo to the corresponding hydroxy derivatives which were methylated to methoxy-3,3-dimethyl-3H-benzofuro[3,2-f][1]benzopyran. All compounds substituted on the A ring were found more potent than the reference compound 1 against Mycobacterium bovis BCG and the virulent strain Mycobacterium tuberculosis H37Rv. The effect of the most active derivatives on mycolate synthesis was explored in order to confirm the preliminary hypothesis of an effect on mycobacterial cell wall biosynthesis. The linear 9-methoxy-2,2-dimethyl-2H-benzofuro[2,3-g][1]benzopyran (46) exhibiting a good antimycobacterial activity and devoid of cytotoxicity appeared to be the most promising compound.

Clinical translation of genotyping and haplotyping data: implementation of in vivo pharmacology experience leading drug prescription to pharmacotyping.

The completion of the Human Genome Project has raised expectations for the translation of genomic knowledge into clinical forms that would lead to improved diagnosis of diseases and identification of new drug targets. Such an opportunity is quite challenging within science and society, although there is still uncertainty regarding its outcomes in new drug development and healthcare. Undoubtedly, however, the recent approval by the US FDA of the first two pharmacogenomic tests for genotyping drug-metabolising enzymes is expected to empower and eventually lead to general applicability of various genetic diagnostic tools to improve pharmacotherapy outcomes in the post-genomic era. To this end, the application of genomic knowledge and technologies in everyday clinical practice leads personalised medicine concepts towards the achievement of individualised drug selection and dosage profiling (i.e. pharmacotyping) for ensuring maximum drug effectiveness and safety. Within this framework, pharmacogenomic information can implement the existing clinical pharmacology experience in clinical diagnosis and drug delivery. The latter can be further advanced through the development of workflow information-based operating systems in healthcare to support the utilisation, assessment and outcome of engaged clinical and genomic information. Such a direction may help to suitably revise and adjust clinical regulatory guidelines as well as clinical pharmacology guidelines. This will further facilitate better designing of clinical trials for new drug development as well as pharmacovigilance registries and evaluation of these data. To critically describe the existing environment, this article comprehensively discusses scientific efforts aimed at making clinical translation of genotyping and haplotyping data more efficient and productive in forms that are readily applicable in everyday healthcare. In addition, specific and systematic pharmacogenomic and clinical attempts related to the development of new molecularly targeted drugs, as well as improvement of the efficacy and safety of commonly prescribed drugs, are presented. To this end, the clinical pharmacogenomic experience gained thus far in the use of tyrosine kinase inhibitors in oncology, as well as the process of empowerment through the use of genomic knowledge of the cardiac safety of drugs modulating the function of the human ether-à-go-go-related gene (HERG) potassium channel, represent examples of how the implementation of clinical experience with genomic information guides the development of new drugs and the improvement of pharmacotherapy outcomes.