The evolving biology of small molecules: controlling cell fate and identity

Small molecules have been playing important roles in elucidating basic biology and treatment of a vast number of diseases for nearly a century, making their use in the field of stem cell biology a comparatively recent phenomenon. Nonetheless, the power of biology-oriented chemical design and synthesis, coupled with significant advances in screening technology, has enabled the discovery of a growing number of small molecules that have improved our understanding of stem cell biology and allowed us to manipulate stem cells in unprecedented ways. This review focuses on recent small molecule studies of (i) the key pathways governing stem cell homeostasis, (ii) the pluripotent stem cell niche, (iii) the directed differentiation of stem cells, (iv) the biology of adult stem cells, and (v) somatic cell reprogramming. In a very short period of time, small molecules have defined a perhaps universally attainable naive ground state of pluripotency, and are facilitating the precise, rapid and efficient differentiation of stem cells into somatic cell populations relevant to the clinic. Finally, following the publication of numerous groundbreaking studies at a pace and consistency unusual for a young field, we are closer than ever to completely eliminating the need for genetic modification in reprogramming.     

siPGK1在调控黑色素瘤细胞对Vemurafenib敏感性中的作用及其机制

目的：研究磷酸甘油酸酯激酶1（PGK1）对BRAF^V600E突变型恶性黑色素瘤（MM）对Vemurafenib （Zelboraf^®）敏感性的影响及其机制。方法：采用分子生物学、细胞生物学、药理学相关实验方法（MTT、Western blot、FCM、Colongenic）探讨：①PGK1以及Vemurafenib对MM细胞的存活增殖能力的影响;②通过siPGK1基因增加Vemurafenib药敏感性的机制。结果：①沉默PGK1基因后再给以BRAF^V600E选择性抑制剂Vemurfenib,MM细胞系的存活率明显下降,并呈一定的剂量依赖性;②siPGK1增加MM细胞对Vemurafenib的药物敏感性与激活凋亡信号通路有关。结论：siPGK1通过激活凋亡信号通路增加MM细胞对Vemurafenib的药物敏感性,从而抑制细胞的存活和增殖能力。     

Advantages and clinical applications of natural killer cells in cancer immunotherapy

The past decade has witnessed a burgeoning of research and further insight into the biology and clinical applications of natural killer (NK) cells. Once thought to be simple innate cells important only as cytotoxic effector cells, our understanding of NK cells has grown to include memory-like responses, the guidance of adaptive responses, tissue repair, and a delicate paradigm for how NK cells become activated now termed “licensing” or “arming.” Although these cells were initially discovered and named for their spontaneous ability to kill tumor cells, manipulating NK cells in therapeutic settings has proved difficult and complex in part due to our emerging understanding of their biology. Therapies involving NK cells may either activate endogenous NK cells or involve transfers of exogenous cells by hematopoietic stem cell transplantation or adoptive cell therapy. Here, we review the basic biology of NK cells, highlighting characteristics which make NK cells particularly useful in cancer therapies. We also explore current treatment strategies that have been used for cancer as well as discuss potential future directions for the field.     

CNS stem cells: Where's the biology (a.k.a. beef)?

Central nervous system (CNS) stem cells have become the subject of many laboratories' efforts, presentations, and publications. Yet, in the stem cell world, CNS cells are viewed with skepticism. This is likely due to a dearth of biology (in vivo function) to accompany a flurry of phenomenological and restorative neurology studies. In this article, we compare and contrast the biological knowledge of adult forebrain epidermal growth factor-responsive neural stem cells that has emerged from our laboratories with that of hematopoietic stem cells, using two recent papers in the latter field as specific examples. A comparison of stem cell location, lineage, and repopulation suggests that our understanding of CNS stem cell biology is immature. We conclude that a greater focus on in vivo biology will enhance our knowledge and understanding of CNS stem cells. © 1998 John Wiley & Sons, Inc. J Neurobiol 36: 307–314, 1998     

Mesenchymal Stromal Cells Support the Viability and Differentiation of Follicular Lymphoma-Infiltrating Follicular Helper T-Cells

The biology of follicular lymphoma (FL) is largely dictated by the immune-effector and stromal cells that comprise its tumor microenvironment. FL-infiltrating T-cell populations that are thought to be fundamental to FL biology are follicular helper T-cells (TFH), follicular regulatory T-cells (TFR), a recently described population that regulates TFH activity, and regulatory T-cells (Treg). These T-cell populations have dynamic interactions with mesenchymal stromal cells (MSCs) in the tumor microenvironment. Whereas MSCs have been shown to support FL B-cell and Treg viability, their effects on FL-infiltrating TFH and TFR cells have not been described. Herein we show that MSCs support the viability of FL-infiltrating TFH and TFR, as well as Tregs, in part through an IL-6-dependent mechanism. We further demonstrate that MSCs mediate TFH to TFR conversion by inducing the expression of FoxP3 in TFH cells, demonstrating for the first time that human TFR can be derived from TFH cells. Given that the balance of TFH and TFR populations likely dictate, in part, the biology of this disease, our data support the potential for targeting MSCs as a therapeutic strategy.     

Mini chamber system for long-term maintenance and observation of cultured cells

We constructed a mini chamber system that was able to maintain cell culture on a microscope for long periods. It is a modified closed system with medium perfusion and CO2 circulation. The closed CO2 circulation and ample air inside the chamber distinguish it from other closed systems. Using different cell lines, the system was shown to be able to support long-term, time-lapse recording. After 229 hours of time-lapse recording, A2058 cells (a melanoma cell line) became overconfluent but still multiplied. Many CAD cells (a murine neuron-like cell line) still moved their cell bodies and kept their neurite-like processes after 28 days of recording. The entire healing process of a scratch-wounded 124 (a bladder cancer cell line) monolayer can be monitored. Such a modified closed system should find many applications in developmental biology, cell biology, and cancer biology where long-term, time-lapse recording is required or when the health of cells is important.     

The emerging functions of the p53-miRNA network in stem cell biology

The p53 pathway plays an essential role in tumor suppression, regulating multiple cellular processes coordinately to maintain genome integrity in both somatic cells and stem cells. Despite decades of research dedicated to p53 function in differentiated somatic cells, we are just starting to understand the complexity of the p53 pathway in the biology of pluripotent stem cells and tissue stem cells. Recent studies have demonstrated that p53 suppresses proliferation, promotes differentiation of embryonic stem (ES) cells and constitutes an important barrier to somatic reprogramming. In addition, emerging evidence reveals the role of the p53 network in the self-renewal, proliferation and genomic integrity of adult stem cells. Interestingly, non-coding RNAs, and microRNAs in particular, are integral components of the p53 network, regulating multiple p53-controlled biological processes to modulate the self-renewal and differentiation potential of a variety of stem cells. Thus, elucidation of the p53-miRNA axis in stem cell biology may generate profound insights into the mechanistic overlap between malignant transformation and stem cell biology.     

The emerging functions of the p53-miRNA network in stem cell biology

The p53 pathway plays an essential role in tumor suppression, regulating multiple cellular processes coordinately to maintain genome integrity in both somatic cells and stem cells. Despite decades of research dedicated to p53 function in differentiated somatic cells, we are just starting to understand the complexity of the p53 pathway in the biology of pluripotent stem cells and tissue stem cells. Recent studies have demonstrated that p53 suppresses proliferation, promotes differentiation of embryonic stem (ES) cells and constitutes an important barrier to somatic reprogramming. In addition, emerging evidence reveals the role of the p53 network in the self-renewal, proliferation and genomic integrity of adult stem cells. Interestingly, non-coding RNAs, and microRNAs in particular, are integral components of the p53 network, regulating multiple p53-controlled biological processes to modulate the self-renewal and differentiation potential of a variety of stem cells. Thus, elucidation of the p53-miRNA axis in stem cell biology may generate profound insights into the mechanistic overlap between malignant transformation and stem cell biology.     

Proliferation of human hematopoietic bone marrow cells in simulated microgravity

Expansion and/or maintenance of hematopoietic stem cell (HSC) potential following in vitro culture remains a major obstacle in stem cell biology and bone marrow (BM) transplantation. Several studies suggest that culture of mammalian cells in microgravity (micro-g) may reduce proliferation and differentiation of these cells. We investigated the application of these findings to the field of stem cell biology in the hopes of expanding HSC with minimal loss of hematopoietic function. To this end, BM CD34+ cells were cultured for 4-6 d in rotating wall vessels for simulation of micro-g, and assessed for expansion, cell cycle activation, apoptosis, and hematopoietic potential. While CD34+ cells cultured in normal gravity (1-g) proliferated up to threefold by day 4-6, cells cultured in micro-g did not increase in number. As a possible explanation for this, cells cultured in simulated micro-g were found to exit G0/G1 phase of cell cycle at a slower rate than 1-g controls. When assayed for primitive hematopoietic potential in secondary conventional 1-g long-term cultures, cells from initial micro-g cultures produced greater numbers of cells and progenitors, and for a longer period of time, than cultures initiated with 1-g control cells. Similar low levels of apoptosis and adhesion molecule phenotype in micro-g and 1-g-cultured cells suggested similar growth patterns in the two settings. These data begin to elucidate the effects of micro-g on proliferation of human hematopoietic cells and may be potentially beneficial to the fields of stem cell biology and somatic gene therapy.     

SDF-1 alone and in co-operation with HGF regulates biology of human cervical carcinoma cells

Stromal Derived Factor-1 (SDF-1)-CXCR4 axis plays a pivotal role in biology and metastasis of several tumors. The aim of this study was to see if SDF-1 alone or in combination with Hepatocyte Growth Factor (HGF) affects biology of human cervical carcinoma (HCC) cells. We found that HCC cell lines investigated in our study highly express CXCR4 on their surface. CXCR4 was also expressed on tumor cells in tissue sections derived from cervical cancer patients. At the same time normal cervical epithelium was negative for CXCR4 expression what suggests a strong correlation between CXCR4 and malignant cell phenotype. Subsequently, we studied a potential role of the SDF-1-CXCR4 axis in HCC and noticed that SDF-1 (i) chemoattracted HCC cells, (ii) enhanced their scattering, (iii) stimulated nuclear localization of beta-catenins and upregulated their target gene cyclin D1 and (iv) at the molecular level induced calcium flux and activated RAS-MAPK, PI3-AKT and JAK-STAT pathways. SDF-1-mediated functions were additionally enhanced in the presence of HGF. Thus, our data show that the SDF-1-CXCR4 axis affects biology of HCC cells. Furthermore, we postulate that this axis might become a potential target to prevent progression of cervical cancer.     

Recent progress in dissecting ubiquitin signals with chemical biology tools

Protein ubiquitination regulates almost all eukaryotic cellular processes, and is of very high complexity due to the diversity of ubiquitin (Ub) modifications including mono-, multiply mono-, homotypic poly-, and even heterotypic poly-ubiquitination. To accurately elucidate the role of each specific Ub signal in different cells with spatiotemporal resolutions, a variety of chemical biology tools have been developed. In this review, we summarize some recently developed chemical biology tools for ubiquitination studies and their applications in molecular and cellular biology.     

骨髓间充质干细胞移植与肾脏病

骨髓间充质干细胞是目前广受关注的一群成体干细胞,具有取材容易,增殖能力强,生物学特性稳定,可以跨胚层分化,低免疫源性,参与受损组织修复等优点,随着组织工程的兴起和发展以及其自身所特有的生物学特性,人们逐渐认识到将骨髓间充质干细胞作为肾脏病移植治疗的种子细胞具有良好的应用前景。本文就骨髓间充质干细胞的生物学特性及其在肾脏病移植治疗中的进展做一综述。     

Anchored cell analysis and sorting (ACAS) system]

Advanced biology and recent technology have provided sophisticated and objective method for analyzing biological characteristics on cells. Following that, many new instruments have developed. Diagnostic immunocytochemistry has become an accepted diagnostic tool in cell biology. In recent years, remarkable advances in technology provide a method for quantitative and objective analyses of cell characteristics. The newly developed computer assisted laser cytometer (ACAS 570) can be applied in clinical basis as well as in research laboratory. Fluorescent intensities of ancharage-dependent cells can be automatically analyzed and make it possible to separate a subpopulation of cells. This computer controlled system principally consists of argon ion laser, phase contrast microscope. Quantitative fluorescence measurements and computer graphic images can be obtained. The present paper demonstrates multiple applications of laser cytometer for evaluation of cell biology.     

进化细胞生物学的提出及其任务

作者提出应创建一门源于进化生物学与细胞生物学两者的交叉学科一进化细胞生物学(细胞的进化生物学)。其根本任务在于用进化的观点考察真核细胞的一切方面,从它们的起源和演化来认识它们的现在。文中列举了其具体的研究内容,并分析了其研究方法上的特点,指出在这里需要把进化生物学的综合性分析与细胞生物学的实验研究最紧密地结合起来。文中还论述了真核细胞的细胞器的“不进化”现象,指出其根本原因在于进化焦点的转移。     

Future challenges for hematopoietic stem cell research

This perspective summarizes several important advances in hematopoietic stem cell (HSC) biology in the past few years and places these advances in the context of future directions in stem cell research. The potential utility of stem cells for gene therapy, tissue engineering, and the treatment of neurological and other forms of disease is simply too significant to ignore, and yet our knowledge and ability to deliver these forms of therapy in a safe and efficacious manner will require additional advances in the understanding of the basic biology of stem cells.     

Biology of cord blood cells and future prospects for enhanced clinical benefit

Cord blood (CB) has served as a clinically beneficial source of hematopoietic stem (HSC) and progenitor (HPC) cells for transplantation and correction of a large number of malignant and non-malignant disorders. The capacity of CB to perform these functions is intimately related to the quality and quantity of HSC and HPC present in CB. This review covers the biology of HSC and HPC, efforts to expand these cells ex vivo for enhanced clinical utility that has thus far not been very successful, and recent studies on attempts to enhance the homing and engrafting capability of HSC as an alternative means for more effective use of the limited numbers of CB cells collected. This review also highlights the presence in CB of mesenchymal stem cells, unrestricted somatic stem cells, endothelial progenitor cells and immune cells. The presence and biology of these non-HSC/HPC may open up future possibilities for additional clinical benefit of CB, a product considered mainly for discard before its clinical transplantation potential was realized in the late 1980s.     

VEGF function in vascular pathogenesis

Vascular endothelial growth factor (VEGF) has proven to be the most critical angiogenic factor identified to date; its discovery has transformed the field of angiogenesis research. After two decades of intense studies by numerous laboratories, the complex biology of VEGF is slowly being elucidated. VEGF is a collection of several different isoforms with overlapping but also unique functions. Furthermore, there are at least four different VEGF receptors, adding to the complexity of the VEGF/receptor system. VEGF exerts its effects on endothelial cells, inflammatory cells and neuronal cells, and its expression may contribute to the pathologies of diseases ranging from retinopathies to cancer. This review focuses on the biochemistry and cell biology of VEGF, with particular emphasis on the different isoforms and receptors, thereby illustrating the multifunctional nature of this growth factor. Lastly, critical considerations based on the complex biology of VEGF for developing specific and more targeted anti-VEGF therapeutic agents will be discussed.     

Induced pluripotent stem cells,a giant leap for mankind therapeutic applications

Induced pluripotent stem cells (iPSC) technology has propelled the field of stem cells biology, providing new cells to explore the molecular mechanisms of pluripotency, cancer biology and aging. A major advantage of human iPSC, compared to the pluripotent embryonic stem cells, is that they can be generated from virtually any embryonic or adult somatic cell type without destruction of human blastocysts. In addition, iPSC can be generated from somatic cells harvested from normal individuals or patients, and used as a cellular tool to unravel mechanisms of human development and to model diseases in a manner not possible before. Besides these fundamental aspects of human biology and physiology that are revealed using iPSC or iPSC-derived cells, these cells hold an immense potential for cell-based therapies, and for the discovery of new or personalized pharmacological treatments for many disorders. Here, we review some of the current challenges and concerns about iPSC technology. We introduce the potential held by iPSC for research and development of novel health-related applications. We briefly present the efforts made by the scientific and clinical communities to create the necessary guidelines and regulations to achieve the highest quality standards in the procedures for iPSC generation, characterization and long-term preservation. Finally, we present some of the audacious and pioneer clinical trials in progress with iPSC-derived cells.     

Human Normal Bronchial Epithelial Cells: A Novel In Vitro Cell Model for Toxicity Evaluation

Human normal cell-based systems are needed for drug discovery and toxicity evaluation. hTERT or viral genes transduced human cells are currently widely used for these studies, while these cells exhibited abnormal differentiation potential or response to biological and chemical signals. In this study, we established human normal bronchial epithelial cells (HNBEC) using a defined primary epithelial cell culture medium without transduction of exogenous genes. This system may involve decreased IL-1 signaling and enhanced Wnt signaling in cells. Our data demonstrated that HNBEC exhibited a normal diploid karyotype. They formed well-defined spheres in matrigel 3D culture while cancer cells (HeLa) formed disorganized aggregates. HNBEC cells possessed a normal cellular response to DNA damage and did not induce tumor formation in vivo by xenograft assays. Importantly, we assessed the potential of these cells in toxicity evaluation of the common occupational toxicants that may affect human respiratory system. Our results demonstrated that HNBEC cells are more sensitive to exposure of 10~20 nm-sized SiO₂, Cr(VI) and B(a)P compared to 16HBE cells (a SV40-immortalized human bronchial epithelial cells). This study provides a novel in vitro human cells-based model for toxicity evaluation, may also be facilitating studies in basic cell biology, cancer biology and drug discovery.