Neural stem cells as tools for drug discovery: novel platforms and approaches

Introduction: Neural stem cells catalyze strong interests for the development of systems to screen for effective drugs to treat neurodegenerative conditions and/or improve neurogenesis, fields where the classical approaches have so far failed in discovering successful drugs.

Areas covered: The authors review the known biology of NSCs, their normal function in development, the adult brain, and in vitro culture systems. The authors also discuss the scientific and technological progress which will aid wider applications of NSCs for drug screening/development purposes. The authors base this article on literature searches performed through PubMed and Google Scholar.

Expert opinion: NSC systems present unique opportunities that are starting to be successfully explored for genetic and chemical screening. These systems provide the possibility of identifying and optimizing molecules/drugs that could lead to the tighter control in self-renewal and lineage specification of NSCs as well as their functional maturation. This could be crucial in moving forward NSC-based therapies. It is expected that recent advances in the method of producing NSCs from patient-specific human induced pluripotent stem (iPS) cells and in the technologies to grow them in vitro, while preserving their full developmental potential, will allow a full exploitation of NSCs both in drug discovery programs and in predictive toxicology studies.     

细胞组学在新药研发中的应用

细胞组学是近年来发展起来的一种致力于确定单细胞分子表型,进而研究细胞结构及分子功能的科学。其本质是使用高灵敏多参数荧光分析方法整合多种单细胞的不同事件,阐释组织和有机体的复杂事件和行为。借助于快速发展的细胞生物成像和生物信息技术及其高内涵和高通量的分析能力,细胞组学已应用到新药筛选、候选药物优化等新药研发的各个阶段,为高效发现创新药物提供了颇具优势的评价体系。     

Embryonic stem cell application in drug discovery

Embryonic stem (ES) cells and their differentiated progeny offer tremendous potential for regenerative medicine, even in the field of drug discovery. There is an urgent need for clinically relevant assays that make use of ES cells because of their rich biological utility. Attention has been focused on small molecules that allow the precise manipulation of cells in vitro, which could allow researchers to obtain homogeneous cell types for cell-based therapies and discover drugs for stimulating the regeneration of endogenous cells. Such therapeutics can act on target cells or their niches in vivo to promote cell survival, proliferation, differentiation, and homing. In the present paper, we reviewed the use of ES cell models for high-throughput/content drug screening and toxicity assessment. In addition, we examined the role of stem cells in large pharmaceutical companies' R&D and discussed a novel subject, nicheology, in stem cell-related research fields.     

Human pluripotent stem cells as tools for neurodegenerative and neurodevelopmental disease modeling and drug discovery

Introduction: Although intensive efforts have been made, effective treatments for neurodegenerative and neurodevelopmental diseases have not been yet discovered. Possible reasons for this include the lack of appropriate disease models of human neurons and a limited understanding of the etiological and neurobiological mechanisms. Recent advances in pluripotent stem cell (PSC) research have now opened the path to the generation of induced pluripotent stem cells (iPSCs) starting from somatic cells, thus offering an unlimited source of patient-specific disease-relevant neuronal cells.

Areas covered: In this review, the authors focus on the use of human PSC-derived cells in modeling neurological disorders and discovering of new drugs and provide their expert perspectives on the field.

Expert opinion: The advent of human iPSC-based disease models has fuelled renewed enthusiasm and enormous expectations for insights of disease mechanisms and identification of more disease-relevant and novel molecular targets. Human PSCs offer a unique tool that is being profitably exploited for high-throughput screening (HTS) platforms. This process can lead to the identification and optimization of molecules/drugs and thus move forward new pharmacological therapies for a wide range of neurodegenerative and neurodevelopmental conditions. It is predicted that improvements in the production of mature neuronal subtypes, from patient-specific human-induced pluripotent stem cells and their adaptation to culture, to HTS platforms will allow the increased exploitation of human pluripotent stem cells in drug discovery programs.     

Systems drug discovery: a quantitative,objective approach for safer drug development

We are currently witnessing a dramatic change in the pharmaceutical industry as many companies are downscaling their efforts to discover new drug candidates and are instead turning toward collaboration with academic partners. This trend has been dubbed open innovation. The reason for this change of policy stems from the realization that, in spite of massive investments in their drug development programs in the past 30 years, the number of new drugs reaching the market has remained stable over the same period. We review past and present drug discovery strategies and present a novel more holistic approach that we term Systems Drug Discovery. This approach aims at quantifying the physiological state of organ slice cultures using high content imaging and metabolomics. The characterization in a quantitative manner of healthy, diseased, and drug-treated tissues will allow defining a multiparametric space, within which tissues are healthy. This in turn will allow an objective assessment of the impact of candidate drugs on cells. This quantitative approach should help guide the development of new drugs reducing failure rates in clinical phase.     

绿色荧光蛋白在药物发现研究中的应用进展

目的药物的设计与筛选是药物研究的重要环节,绿色荧光蛋白(green fluorescent protein,GFP)在药物发现研究中有着重要的意义和价值。方法通过综述22篇中、英文文献,在化学药物基因药物等方面介绍了绿色荧光蛋白及其在药物发现研究中的应用。结果绿色荧光蛋白最早发现于美国西北海岸的水母中,在紫外照射下可以产生明亮的绿色荧光。它具有很多理想性的特征,如对酸、碱、氧化还原剂等许多化学试剂有极强的稳定性,因此常被于活体细胞或组织的跟踪、标记中,被喻为"活的"分子探针。通过监测绿色荧光蛋白可以对体内基因表达、细胞内蛋白质原位定位,观测肿瘤发生、生长、转移等过程,提供重要生物学靶标有效信息。结论绿色荧光蛋白在药物设计和筛选等领域展示了广阔前景,它与药物设计、药物筛选的结合将为新药研究和开发注入新的活力。     

The development of high-content screening (HCS) technology and its importance to drug discovery

ABSTRACT

Introduction: High-content screening (HCS) was introduced about twenty years ago as a promising analytical approach to facilitate some critical aspects of drug discovery. Its application has spread progressively within the pharmaceutical industry and academia to the point that it today represents a fundamental tool in supporting drug discovery and development.

Areas covered: Here, the authors review some of significant progress in the HCS field in terms of biological models and assay readouts. They highlight the importance of high-content screening in drug discovery, as testified by its numerous applications in a variety of therapeutic areas: oncology, infective diseases, cardiovascular and neurodegenerative diseases. They also dissect the role of HCS technology in different phases of the drug discovery pipeline: target identification, primary compound screening, secondary assays, mechanism of action studies and in vitro toxicology.

Expert opinion: Recent advances in cellular assay technologies, such as the introduction of three-dimensional (3D) cultures, induced pluripotent stem cells (iPSCs) and genome editing technologies (e.g., CRISPR/Cas9), have tremendously expanded the potential of high-content assays to contribute to the drug discovery process. Increasingly predictive cellular models and readouts, together with the development of more sophisticated and affordable HCS readers, will further consolidate the role of HCS technology in drug discovery.     

Challenges for drug discovery and development in China

Introduction: The drug development industry is restructuring worldwide in terms of the research and development process. As with pharmaceuticals in the west, China faces major challenges for drug discovery and development.

Areas covered: In this review, the authors discuss anti-cancer, anti-allergy, anti-infectious, and proprietary Chinese Medicines (pCM) for various chronic diseases (such as the allergic diseases: eczema, asthma and allergic rhinitis), which remain the contemporary therapeutic strategies that are being explored and developed. Drug transporters, disease specific biomarkers, pharmacophores, bioactive natural products and pharmacogenetics are some aspects of research technologies. Proprietary Chinese medicine remains one of the most popular strategies. There is however the issue of good research documentation of efficacy versus adverse effects. China has a complex healthcare system involving a large patient pool.

Expert opinion: Various factors can impact drug development in China including the concurrent use of both western and Chinese medicines, pharmacogenetic variances, lack of multidisciplinary team impact on disease management and drug safety. China may adopt the current development of big data analysis in other countries such as UK and US to build and centralize a nationwide database for better monitoring and clinical evaluation to provide more efficient care at a lower cost.     

Microsomal cytochrome P450 as a target for drug discovery and repurposing

Cytochrome P450 (P450) enzymes are ancient electron-transfer-chain system of remarkable biological importance. Microsomal P450 enzymes are the P450 attached to endoplasmic reticulum, which, in humans, are critical for body’s defenses against xenobiotics by mediating their metabolism, and cell signaling by mediating arachidonic acid (AA) transformation to several potent bioactive molecules. Only recently, modulating P450-mediated AA metabolism has risen as a promising new drug target. This review presents the therapeutic potential of finding effective, selective and safe treatments targeting P450-mediated AA metabolism, and the several approaches that have been used to find these treatments; among which, our focus was on modulators of P450 activities. We detailed the efforts done to develop new molecular entities designed to modulate P450, and the more recent efforts tried to employ our previous knowledge on drug metabolism to repurpose old drugs with the capacity to alter P450-mediated drug metabolism to target AA metabolism. Because of the long recognition of P450 role in xenobiotic metabolism, several clinically approved agents were identified to alter P450 activity. Repurposing old drugs as P450 modulators can facilitate bringing treatments targeting P450-mediated AA metabolism to clinical trials. However, the capacity of the modulation of P450-derived AA metabolites of clinically approved drugs has to be systematically investigated and validated for their new use in humans.     

Stem cell signaling as a target for novel drug discovery: recent progress in the WNT and Hedgehog pathways

One of the most exciting fields in biomedical research over the past few years is stem cell biology, and therapeutic application of stem cells to replace the diseased or damaged tissues is also an active area in development. Although stem cell therapy has a number of technical challenges and regulatory hurdles to overcome, the use of stem cells as tools in drug discovery supported by mature technologies and established regulatory paths is expected to generate more immediate returns. In particular, the targeting of stem cell signaling pathways is opening up a new avenue for drug discovery. Aberrations in these pathways result in various diseases, including cancer, fibrosis and degenerative diseases. A number of drug targets in stem cell signaling pathways have been identified. Among them, WNT and Hedgehog are two most important signaling pathways, which are the focus of this review. A hedgehog pathway inhibitor, vismodegib (Erivedge), has recently been approved by the US FDA for the treatment of skin cancer, while several drug candidates for the WNT pathway are entering clinical trials. We have discovered that the stem cell signaling pathways respond to traditional Chinese medicines. Substances isolated from herbal medicine may act specifically on components of stem cell signaling pathways with high affinities. As many of these events can be explained through molecular interactions, these phenomena suggest that discovery of stem cell-targeting drugs from natural products may prove to be highly successful.     

Improvement of cardiac efficacy and safety models in drug discovery by the use of stem cell-derived cardiomyocytes

Background: The pharmaceutical industry suffers from high attrition rates during late phases of drug development. Improved models for early evaluation of drug efficacy and safety are needed to address this problem. Recent developments have illustrated that human stem cell-derived cardiomyocytes are attractive for using as a model system for different cardiac diseases and as a model for screening, safety pharmacology and toxicology. Objective: In this review, we discuss contemporary drug discovery models and their characteristics for cardiac efficacy testing and safety assessment. Additionally, we evaluate various sources of stem cells and how these cells could potentially improve early screening and safety models. Conclusion: We conclude that human stem cells offer a source of physiologically relevant cells that show great potential as a future tool in cardiac drug discovery. However, some technical challenges related to cell differentiation and production and also to validation of improved platforms remain and must be overcome before successful application can become a reality.     

Stem cells and small molecule screening: haploid embryonic stem cells as a new tool

Stem cells can both self-renew and differentiate into various cell types under certain conditions, which makes them a good model for development and disease studies. Recently, chemical approaches have been widely applied in stem cell biology by promoting stem cell self-renewal, proliferation, differentiation and somatic cell reprogramming using specific small molecules. Conversely, stem cells and their derivatives also provide an efficient and robust platform for small molecule and drug screening. Here, we review the current research and applications of small molecules that modulate stem cell self-renewal and differentiation and improve reprogramming, as well as the applications that use stem cells as a tool for small molecule screening. Moreover, we introduce the recent advance in haploid embryonic stem cells research. Haploid embryonic stem cells maintain haploidy and stable growth over extensive passages, possess the ability to differentiate into all three germ layers in vitro and in vivo, and contribute to the germlines of chimeras when injected into blastocysts. Androgenetic haploid stem cells can also be used in place of sperm to produce fertile progeny after intracytoplasmic injection into mature oocytes. Such characteristics demonstrate that haploid stem cells are a new approach for genetic studies at both the cellular and animal levels and that they are a valuable platform for future small molecule screening.     

iPSCs and small molecules: a reciprocal effort towards better approaches for drug discovery

The revolutionary induced pluripotent stem cell (iPSC) technology provides a new path for cell replacement therapies and drug screening. Patient-specific iPSCs and subsequent differentiated cells manifesting disease phenotypes will finally position human disease pathology at the core of drug discovery. Cells used to test the toxic effects of drugs can also be generated from normal iPSCs and provide a much more accurate and cost-effective system than many animal models. Here, we highlight the recent progress in iPSC-based cell therapy, disease modeling and drug evaluations. In addition, we discuss the use of small molecule drugs to improve the generation of iPSCs and understand the reprogramming mechanism. It is foreseeable that the interplay between iPSC technology and small molecule compounds will push forward the applications of iPSC-based therapy and screening systems in the real world and eventually revolutionize the methods used to treat diseases.     

Role of transport proteins in drug discovery and development: a pharmaceutical perspective

1.?This review will explore, from a pharmaceutical industry perspective, the evidence and consequences of transport protein involvement in pharmacokinetic variability and safety of drugs in humans. With the preclinical and clinical evidence available, the transport proteins that are considered to be the most important in respect of pharmacokinetic variability and safety in humans will be highlighted.

2.?A large number of transport proteins have been identified, at both the genetic and the cellular level, which have been suggested to play some role in the absorption, distribution or elimination of endogenous, xenobiotic or drug substrates.

3.?The weight of evidence suggests that only a small number of transport proteins need to be routinely considered in the drug-discovery setting driven by the magnitude of their impact on tissue distribution, pharmacokinetic variability and drug–drug interactions.

4.?For the majority of candidate drugs, an assessment of the role of transporter proteins in their disposition and safety need only be assessed if in vivo properties suggest that active transport is likely to be a significant factor, if transport proteins are implicated in a particular therapeutic target area or if the disposition and safety of a likely co-medication are known to be significantly modulated by transport proteins.     

Principles and applications of Raman spectroscopy in pharmaceutical drug discovery and development

Introduction: In recent years, Raman spectroscopy has become increasingly important as an analytical technique in various scientific areas of research and development. This is partly due to the technological advancements in Raman instrumentation and partly due to detailed fingerprinting that can be derived from Raman spectra. Its versatility of applications, rapidness of collection and easy analysis have made Raman spectroscopy an attractive analytical tool.

Areas covered: The following review describes Raman spectroscopy and its application within the pharmaceutical industry. The authors explain the theory of Raman scattering and its variations in Raman spectroscopy. The authors also highlight how Raman spectra are interpreted, providing examples.

Expert opinion: Raman spectroscopy has a number of potential applications within drug discovery and development. It can be used to estimate the molecular activity of drugs and to establish a drug’s physicochemical properties such as its partition coefficient. It can also be used in compatibility studies during the drug formulation process. Raman spectroscopy’s immense potential should be further investigated in future.