Modifying enzyme replacement therapy – A perspective

Several diseases are caused by the lack of functional proteins, including lysosomal storage diseases or haemophilia A and B. Patients suffering from one of these diseases are treated via enzyme replacement therapies to restore the missing protein. Although this treatment strategy prevents some disease symptoms, enzyme replacement therapies are very expensive and require very frequent infusions, which can cause infusion adverse reactions and massively impair the quality of life of the patients. This review proposes a technology to sustainably produce proteins within the patient to potentially make frequent protein-infusions redundant. This technology is based on blood circulating immune cells as producers of the needed therapeutic protein. To ensure a stable protein concentration over time the cells are equipped with a system, which induces cell proliferation when low therapeutic protein levels are detected and a system inhibiting cell proliferation when high therapeutic protein levels are detected.     

Stem cell therapy for Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by memory loss and cognitive impairment. It is caused by synaptic failure and excessive accumulation of misfolded proteins. To date, almost all advanced clinical trials on specific AD-related pathways have failed mostly due to a large number of neurons lost in the brain of patients with AD. Also, currently available drug candidates intervene too late. Stem cells have improved characteristics of self-renewal, proliferation, differentiation, and recombination with the advent of stem cell technology and the transformation of these cells into different types of central nervous system neurons and glial cells. Stem cell treatment has been successful in AD animal models. Recent preclinical studies on stem cell therapy for AD have proved to be promising. Cell replacement therapies, such as human embryonic stem cells or induced pluripotent stem cell–derived neural cells, have the potential to treat patients with AD, and human clinical trials are ongoing in this regard. However, many steps still need to be taken before stem cell therapy becomes a clinically feasible treatment for human AD and related diseases. This paper reviews the pathophysiology of AD and the application prospects of related stem cells based on cell type.     

神经干细胞移植的临床研究进展

神经系统损伤会导致脑内神经干细胞（neural stem cells,NSCs）的扩增以实现自我修复功能,而通过外源细胞移植的方式来加速这一进程,可能是一种更有效的治疗手段。当前,神经干细胞临床研究所面临的主要问题是如何评价细胞在移植后的行为和功能。该文综述了近几年使用神经干细胞移植治疗几种主要神经系统疾病的临床研究成果,并着重关注了干细胞移植后的示踪研究。     

Proteome-wide analysis of neural stem cell differentiation to facilitate transition to cell replacement therapies

Neurodegenerative diseases are devastating disorders and the demands on their treatment are set to rise in connection with higher disease incidence. Knowledge of the spatiotemporal profile of cellular protein expression during neural differentiation and definition of a set of markers highly specific for targeted neural populations is a key challenge. Intracellular proteins may be utilized as a readout for follow-up transplantation and cell surface proteins may facilitate isolation of the cell subpopulations, while secreted proteins could help unravel intercellular communication and immunomodulation. This review summarizes the potential of proteomics in revealing molecular mechanisms underlying neural differentiation of stem cells and presents novel candidate proteins of neural subpopulations, where understanding of their functionality may accelerate transition to cell replacement therapies.     

Trace levels of innate immune response modulating impurities (IIRMIs) synergize to break tolerance to therapeutic proteins

Therapeutic proteins such as monoclonal antibodies, replacement enzymes and toxins have significantly improved the therapeutic options for multiple diseases, including cancer and inflammatory diseases as well as enzyme deficiencies and inborn errors of metabolism. However, immune responses to these products are frequent and can seriously impact their safety and efficacy. Of the many factors that can impact protein immunogenicity, this study focuses on the role of innate immune response modulating impurities (IIRMIs) that could be present despite product purification and whether these impurities can synergize to facilitate an immunogenic response to therapeutic proteins. Using lipopolysaccharide (LPS) and CpG ODN as IIRMIs we showed that trace levels of these impurities synergized to induce IgM, IFNγ, TNFα and IL-6 expression. In vivo, trace levels of these impurities synergized to increase antigen-specific IgG antibodies to ovalbumin. Further, whereas mice treated with human erythropoietin showed a transient increase in hematocrit, those that received human erythropoietin containing low levels of IIRMIs had reduced response to erythropoietin after the 1(st) dose and developed long-lasting anemia following subsequent doses. This suggests that the presence of IIRMIs facilitated a breach in tolerance to the endogenous mouse erythropoietin. Overall, these studies indicate that the risk of enhancing immunogenicity should be considered when establishing acceptance limits of IIRMIs for therapeutic proteins.     

Stem cell therapies in cardiac diseases: Current status and future possibilities

Cardiovascular diseases represent the world’s leading cause of death. In this heterogeneous group of diseases, ischemic cardiomyopathies are the most devastating and prevalent, estimated to cause 17.9 million deaths per year. Despite all biomedical efforts, there are no effective treatments that can replace the myocytes lost during an ischemic event or progression of the disease to heart failure. In this context, cell therapy is an emerging therapeutic alternative to treat cardiovascular diseases by cell administration, aimed at cardiac regeneration and repair. In this review, we will cover more than 30 years of cell therapy in cardiology, presenting the main milestones and drawbacks in the field and signaling future challenges and perspectives. The outcomes of cardiac cell therapies are discussed in three distinct aspects: The search for remuscularization by replacement of lost cells by exogenous adult cells, the endogenous stem cell era, which pursued the isolation of a progenitor with the ability to induce heart repair, and the utilization of pluripotent stem cells as a rich and reliable source of cardiomyocytes. Acellular therapies using cell derivatives, such as microvesicles and exosomes, are presented as a promising cell-free therapeutic alternative.     

Plasma derivatives: new products and new approaches

The infusion of plasma-derived or recombinant factors to treat bleeding disorders such as hemophilia A and B is a success story in the management of a chronic disease. The effectiveness of this approach is however limited by challenges with adverse effects of treatment. The most notable of these are the development of inhibitory antibodies that target the protein therapeutic. The current standard of care for management of hemophiliacs is prophylactic treatment that includes frequent infusions of a Factor VIII product. Failure to comply with the prophylactic regimen is a major hurdle in the management of these patients. We discuss here more recent findings that argue for a pharmacogenetic approach to understanding (and eventually circumventing) immunogenicity. We also review strategies used to bioengineer coagulation factors to extend the half-lives of coagulation proteins. The rapid progress in the last few years to bioengineer coagulation factors in different ways to attain this goal is described. Finally, novel technologies and potential products are emerging that utilize synthetic molecules in lieu of replacement proteins obviating the limitations associated with replacement therapies.     

Tissue engineering and cell based therapies,from the bench to the clinic: The potential to replace,repair and regenerate

The field of Regenerative Biology as it applies to Regenerative Medicine is an increasingly expanding area of research with hopes of providing therapeutic treatments for diseases and/or injuries that conventional medicines and even new biologic drug therapies cannot effectively treat. Extensive research in the area of Regenerative Medicine is focused on the development of cells, tissues and organs for the purpose of restoring function through transplantation. The general belief is that replacement, repair and restoration of function is best accomplished by cells, tissues or organs that can perform the appropriate physiologic/metabolic duties better than any mechanical device, recombinant protein therapeutic or chemical compound. Several strategies are currently being investigated and include, cell therapies derived from autologous primary cell isolates, cell therapies derived from established cell lines, cell therapies derived from a variety of stem cells, including bone marrow/mesenchymal stem cells, cord blood stem cells, embryonic stem cells, as well as cells tissues and organs from genetically modified animals. This mini-review is not meant to be exhaustive, but aims to highlight clinical applications for the four areas of research listed above and will address a few key advances and a few of the hurdles yet to be overcome as the technology and science improve the likelihood that Regenerative Medicine will become clinically routine.     

Multiplexed targeting of microRNA in stem cell-derived extracellular vesicles for regenerative medicine

Regenerative medicine is a research field that develops methods to restore damaged cell or tissue function by regeneration, repair or replacement. Stem cells are the raw material of the body that is ultimately used from the point of view of regenerative medicine, and stem cell therapy uses cells themselves or their derivatives to promote responses to diseases and dysfunctions, the ultimate goal of regenerative medicine. Stem cell-derived extracellular vesicles (EVs) are recognized as an attractive source because they can enrich exogenous microRNAs (miRNAs) by targeting pathological recipient cells for disease therapy and can overcome the obstacles faced by current cell therapy agents. However, there are some limitations that need to be addressed before using miRNA-enriched EVs derived from stem cells for multiplexed therapeutic targeting in many diseases. Here, we review various roles on miRNA-based stem cell EVs that can induce effective and stable functional improvement of stem cell-derived EVs. In addition, we introduce and review the implications of several miRNA-enriched EV therapies improved by multiplexed targeting in diseases involving the circulatory system and nervous system. This systemic review may offer potential roles for stem cell-derived therapeutics with multiplexed targeting.     

利用成体干细胞治疗糖尿病

糖尿病是一类严重的代谢疾病, 正危害着世界上越来越多人口的健康。胰岛移植是一种治疗糖尿病的有效方法,却因供体缺乏和移植后免疫排斥问题制约了其广泛应用。干细胞为具有强增殖能力和多向分化潜能的细胞, 是利用细胞替代疗法治疗重大疾病的细胞来源之一, 其中成体干细胞因不存在致瘤性及伦理道德问题而被人们寄予厚望。成体胰腺干细胞在活体损伤及离体培养条件下均能产生胰岛素分泌细胞, 肝干细胞、骨髓干细胞和肠干细胞等在特定离体培养条件下或经过遗传改造后也均可产生胰岛素分泌细胞, 将这些干细胞来源的胰岛素分泌细胞移植到模型糖尿病小鼠中可以治疗糖尿病。因而, 成体干细胞可以为细胞替代疗法治疗糖尿病提供丰富的胰岛供体来源。     

IscU2对非小细胞肺癌增殖、迁移、侵袭能力的影响及其作用机制的研究

该文通过shRNA干扰技术敲低IscU2干扰细胞IscU2的表达,研究了干扰IscU2对非小细胞肺癌(NSCLC)细胞NCI-H520增殖、迁移及侵袭能力的影响。构建了稳定低表达IscU2的非小细胞肺癌细胞系NCI-H520;采用CCK-8和平板克隆实验检测细胞的增殖能力;流式细胞仪检测细胞周期、凋亡、ROS、线粒体膜电位变化情况;Transwell实验检测细胞迁移及侵袭能力;Western blot检测相关蛋白的表达。结果表明,干扰IscU2后,非小细胞肺癌细胞的增殖及克隆形成能力降低;细胞周期停滞在G1/G0期,同时伴随有p-AKT和Cyclin D1蛋白含量的下降;细胞晚期凋亡率明显增加,凋亡蛋白Cleaved-caspase3和Cleaved-PARP表达上调;细胞迁移和侵袭能力降低,上皮标志物E-Cadherin表达上调,间质标志物N-Cadherin和Snail表达下调;细胞ROS积累和线粒体膜电位下降。该研究结果表明,干扰IscU2显著抑制非小细胞肺癌的增殖、迁移、侵袭能力和上皮–间质转化,这为非小细胞肺癌的诊断和治疗提供了新的潜在靶点和视角。     

Combined bezafibrate,medroxyprogesterone acetate and valproic acid treatment inhibits osteosarcoma cell growth without adversely affecting normal mesenchymal stem cells

Drug repurposing is a cost-effective means of targeting new therapies for cancer. We have examined the effects of the repurposed drugs, bezafibrate, medroxyprogesterone acetate and valproic acid on human osteosarcoma cells, i.e., SAOS2 and MG63 compared with their normal cell counterparts, i.e. mesenchymal stem/stromal cells (MSCs). Cell growth, viability and migration were measured by biochemical assay and live cell imaging, whilst levels of lipid-synthesising enzymes were measured by immunoblotting cell extracts. These drug treatments inhibited the growth and survival of SAOS2 and MG63 cells most effectively when used in combination (termed V-BAP). In contrast, V-BAP treated MSCs remained viable with only moderately reduced cell proliferation. V-BAP treatment also inhibited migratory cell phenotypes. MG63 and SAOS2 cells expressed much greater levels of fatty acid synthase and stearoyl CoA desaturase 1 than MSCs, but these elevated enzyme levels significantly decreased in the V-BAP treated osteosarcoma cells prior to cell death. Hence, we have identified a repurposed drug combination that selectively inhibits the growth and survival of human osteosarcoma cells in association with altered lipid metabolism without adversely affecting their non-transformed cell counterparts.     

Silencing FLIPL modifies TNF-induced apoptotic protein expression

Death-receptor induced apoptosis is regulated by FLIP [FLICE (Fas-associated protein with death domain-like IL-1β-converting enzyme)-inhibitory protein] via modification of caspase-8 activation. As an important modulator of apoptosis, the long isoform, FLIP_L, regulates life and death in many various types of normal and tumor cells and tissues to render resistance to death receptor-mediated apoptosis. In addition, FLIP_L has been shown to be involved in regulation of intrinsic (mitochondrial) pathways of apoptosis as well as regulating other proteins involved in cytoprotection and cell cycle progression. Therefore, understanding the role of FLIP_L in complex regulatory networks of cell survival/death mechanisms is vital for future developments to control diseases such as cancer. Here, we shown that silencing FLIP_L in HEK 293 cells changed the expression levels of proteins that are involved in both extrinsic and intrinsic apoptosis, as well as regulating tumor necrosis factor-α (TNF)-mediated apoptotic patterns. We also show that FLIP_L-silenced cells have a lower rate of proliferation and cell cycle progression when compared to control cells. Moreover, treatment with TNF restored proliferation rates in FLIP_L-silenced cells back to more normal levels when compared to control cells. These results suggest that cells have evolved complex compensatory mechanisms to overcome the absence of a key apoptotic regulatory proteins.     

ReNCell VM conditioned medium enhances the induction of dental pulp stem cells into dopaminergic like cells

Among the debilitating diseases, neurological related diseases are the most challenging ones to be treated using cell replacement therapies. Recently, dental pulp stem cells (SHED) were found to be most suitable cell choice for neurological related diseases as evidenced with many preclinical studies. To enhance the neurological potential of SHED, we recapitulated one of the pharmacological therapeutic tools in cell replacement treatment, we pre-conditioned dental pulp stem cells (SHED) with culture medium of ReNCell VM, an immortalized neuron progenitor cell, prior to neurogenesis induction and investigated whether this practice enhances their neurogenesis potential especially towards dopaminergic neurons. We hypothesed that the integration of pharmacological practices such as co-administration of various drugs, a wide range of doses and duration as well as pre-conditioning into cell replacement may enhance the efficacy of stem cell therapy. In particular, pre-conditioning is shown to be involved in the protective effect from some membrano-tropic drugs, thereby improving the resistance of cell structures and homing capabilities. We found that cells pre-treated with ReNCell VM conditioned medium displayed bipolar structures with extensive branches resembling putative dopaminergic neurons as compared to non-treated cells. Furthermore, many neuronal related markers such as NES, NR4A2, MSI1, and TH were highly expressed (fold changes > 2; p < 0.05) in pre-treated cells. Similar observations were detected at the protein level. The results demonstrate for the first time that SHED pre-conditioning enhances neurological potential and we suggest that cells should be primed to their respective environment prior to transplantation.     

Intrinsic resistance of neural stem cells to toxic metabolites may make them well suited for cell non-autonomous disorders: evidence from a mouse model of Krabbe leukodystrophy

While transplanted neural stem cells (NSCs) have been shown to hold promise for cell replacement in models of a number of neurological disorders, these examples have typically been under conditions where the host cells become dysfunctional due to a cell autonomous etiology, i.e. a 'sick' cell within a relatively supportive environment. It has long been held that cell replacement in a toxic milieu would not likely be possible; donor cells would succumb in much the same way as endogenous cells had. Many metabolic diseases are characterized by this situation, suggesting that they would be poor targets for cell replacement therapies. On the other hand, models of such diseases could prove ideal for testing the capacity for cell replacement under such challenging conditions. In the twitcher (twi ) mouse -- as in patients with Krabbe or globoid cell leukodystrophy (GLD), for which it serves as an authentic model -- loss of galactocerebrosidase (GalC) activity results in the accumulation of psychosine, a toxic glycolipid. Twi mice, like children with GLD, exhibit inexorable neurological deterioration presumably as a result of dysfunctional and ultimately degenerated oligodendrocytes with loss of myelin. It is believed that GLD pathophysiology is related to a psychosine-filled environment that kills not only host oligodendrocytes but theoretically any new cells placed into that milieu. Through the implantation of NSCs into the brains of both neonatal and juvenile/young adult twi mice, we have determined that widespread oligodendrocyte replacement and remyelination is feasible. NSCs appear to be intrinsically resistant to psychosine -- more so in their undifferentiated state than when directed ex vivo to become oligodendrocytes. This resistance can be enhanced by engineering the NSCs to over-express GalC. Some twi mice grafted with such engineered NSCs had thicker white tracts and lived 2-3 times longer than expected. While their brains had detectable levels of GalC, it was probably more significant that their psychosine levels were lower than in twi mice that died at a younger age. This concept of resistance based on differentiation state extended to human NSCs which could similarly survive within the twi brain. Taken together, these results suggest a number of points regarding cellular therapies against degenerative diseases with a prominent cell non-autonomous component: Cell replacement is possible if cells resistant to the toxic environment are employed. Furthermore, an important aspect of successful treatment will likely be not only cell replacement but also cross-correction of host cells to provide them with enzyme activity and hence resistance. While oligodendrocyte replacement alone was not a sufficient treatment for GLD (even when extensive), the replacement of both cells and molecules -- e.g. with NSCs that could both become oligodendrocytes and 'pumps' for GalC -- emerges as a promising basis for a multidisciplinary strategy. Most neurological disease are complex in this way and will likely require multifaceted approaches, perhaps with NSCs serving as the 'glue'.     

Neurofilament protein aggregation in a cell line model system

Protein aggregates are associated with many diseases and even aggregates of proteins that have no role in disease are inherently toxic to both neuronal and non-neuronal cells. We have developed a model system to explore the mechanism of protein aggregation using a mouse muscle cell line expressing chimeric neurofilament (NF) proteins, a constituent of the protein aggregates in ALS, Lewy body dementia, and Charcot-Marie-Tooth disease. Formation of protein aggregates in these cells leads to reduced cell viability and activated caspases. Aggregates contained both chimeric NF proteins and ubiquitin by immunolocalization and were predominately cytosolic when proteins were expressed at low levels or for shorter periods of time but were present in the nucleus when expression levels increased. This system represents a flexible, new tool to decipher the molecular mechanism of protein aggregation and the contributions of aggregation to cell toxicity.     

Unraveling molecular effects of ADAR1 overexpression in HEK293T cells by label-free quantitative proteomics

ADAR1 is a double-stranded RNA (dsRNA) editing enzyme that specifically converts adenosine to inosine. ADAR1 is ubiquitously expressed in eukaryotes and participate in various cellular processes such as differentiation, proliferation and immune responses. We report here a new proteomics study of HEK293T cells with and without ADAR1 overexpression. The up- and down-regulated proteins by ADAR1 overexpression are identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) followed by label-free protein quantification. Totally 1,495 proteins (FDR < 0.01) are identified, among which 211 are up- and 159 are down-regulated for at least 1.5-fold (n = 3, p < 0.05). Gene ontology analysis reveals that these ADAR1-regulated proteins are involved in protein translation and cell cycle regulation. Bioinformatics analysis identifies a closely related network consistent for the protein translation machinery and a tightly connected network through proliferating cell nuclear antigen (PCNA)-interactions. Up-regulation of the proteins in the PCNA-mediated cell proliferation network is confirmed by Western blotting. In addition, ADAR1 overexpression is confirmed to increase cell proliferation in HEK293T cells and A549 cells. We conclude that ADAR1 overexpression modulates the protein translation and cell cycle networks through PCNA-mediated protein-protein interaction to promote cell proliferation in HEK293 cells.     

禽流感病毒NS1蛋白对细胞的影响

NS1蛋白为流感病毒非结构蛋白,只在病毒侵入宿主细胞后产生.目前NS1蛋白对细胞整体水平上的作用仍不清楚,为了解NS1蛋白在病毒感染细胞中的作用,构建了重组质粒pCMV-myc-NS1并将其转染A549细胞,利用双向电泳技术检测了受NS1蛋白调控的宿主蛋白,以期从蛋白质组水平上研究禽流感病毒与宿主细胞间的相互作用.同时,还检测了转染NS1对细胞增殖和细胞周期的影响.结果显示,NS1在细胞中的表达,能够明显引起宿主细胞代谢的变化,并通过阻滞细胞周期的正常进行而减缓细胞的增殖.