Microbial factories for recombinant pharmaceuticals

Most of the hosts used to produce the 151 recombinant pharmaceuticals so far approved for human use by the Food and Drug Administration (FDA) and/or by the European Medicines Agency (EMEA) are microbial cells, either bacteria or yeast. This fact indicates that despite the diverse bottlenecks and obstacles that microbial systems pose to the efficient production of functional mammalian proteins, namely lack or unconventional post-translational modifications, proteolytic instability, poor solubility and activation of cell stress responses, among others, they represent convenient and powerful tools for recombinant protein production. The entering into the market of a progressively increasing number of protein drugs produced in non-microbial systems has not impaired the development of products obtained in microbial cells, proving the robustness of the microbial set of cellular systems (so far Escherichia coli and Saccharomyces cerevisae) developed for protein drug production. We summarize here the nature, properties and applications of all those pharmaceuticals and the relevant features of the current and potential producing hosts, in a comparative wa

Protein aggregation and soluble aggregate formation screened by a fast microdialysis assay

Protein aggregation is a major obstacle in recombinant protein production as it reduces the yield of soluble polypeptides. Also, the formation of aggregates occurring in the soluble fraction is more common than formerly expected, and the prevalence of these entities might significantly affect the average quality of the soluble protein species. Usually, the formation of soluble aggregates remains unperceived because analytical methods such as dynamic light scattering are not routinely applied as quality control procedures. The authors have developed a methodologically simple and fast procedure, based on microdialysis and image processing, that reveals the aggregation tendency of a given protein in a specific environment. Because they also show a good correlation between macroscopic aggregation and soluble aggregate formation, the microdialysis approach also permits an estimation of the occurrence of soluble aggregates

Development and characterization of artificial viruses for gene therapy

A portada: Institut de Biotecnologia i de BiomedicinaEls riscos biològics associats a la teràpia gènica viral limiten el ple desenvolupament de vectors virals i plantegen importants problemes a la seva incorporació en assajos clínics. La teràpia gènica no viral representa una alternativa segura als virus naturals per al lliurament dirigida de gens a cèl·lules, tot i els baixos nivells d'expressió gènica obtinguts que és l'obstacle principal per la seva aplicació terapèutica. Els diferents tipus de vectors no virals que s'han desenvolupat fins ara, inclouen els basats en liposomes, dendrímers o proteïnes. Recentment, el concepte de "virus artificial" s'ha proposat per descriure nanocomplexes per al lliurament de gens que imiten les funcions virals pertinents per a la captació del gen i el tràfic intracel·lular. Entre ells, els basats en proteïnes i construïts a través de principis modulars permeten la incorporació, en un únic polipèptid, de diferents proteïnes o dominis de proteïnes amb funcions similars a virus, és a dir, la unió i la condensació a ADN, la unió al receptor, la internalització, l'escapament endosomal, la localització nuclear i l'alliberament del material transportat. Hem desenvolupat una sèrie de vehicles proteics modulars formades per diferents dominis funcionals que són capaços d'entrar en les cèl·lules a través de la unió un receptor específic i promoure nivells importants de l'expressió gènica. En aquesta tesi s'analitza aquest enfocament amb dos articles de revisió i es demostra amb tres treballs originals.The biological risks associated to viral gene therapy limit the full development of viral vectors and pose major concerns to their incorporation into clinical trials. Non-viral gene therapy represents a safe alternative to natural viruses for cell targeted gene delivery, although the low gene expression levels achieved by non-viral vectors are a main obstacle for their therapeutic application. Different types of non-viral vectors have been developed up to date, including those based in liposomes, dendrimers or proteins. Recently, the 'Artificial virus' concept has been proposed to describe nanocomplexes for gene delivery that mimic the viral functions relevant to gene uptake and intracellular trafficking. Among them, those based on proteins and constructed through modular principles allow the incorporation, in a single polypeptide, of different proteins or protein domains with virus-like functions, namely DNA binding and condensation, receptor binding, internalization, endosomal escape, nuclear targeting and uncoating. We have developed a series of protein-only modular vehicles composed by different functional domains that are able to enter cells through specific receptor binding and promotes important levels of transgene expression. In this thesis this approach is discussed with two review articles and demonstrated with three original papers

Intracellular CXCR4 + cell targeting with T22-empowered protein-only nanoparticles

Cell-targeting peptides or proteins are appealing tools in nanomedicine and innovative medicines because they increase the local drug concentration and reduce potential side effects. CXC chemokine receptor 4 (CXCR4) is a cell surface marker associated with several severe human pathologies, including colorectal cancer, for which intracellular targeting agents are currently missing. Four different peptides that bind CXCR4 were tested for their ability to internalize a green fluorescent protein-based reporter nanoparticle into CXCR4 + cells. Among them, only the 18 mer peptide T22, an engineered segment derivative of polyphemusin II from the horseshoe crab, efficiently penetrated target cells via a rapid, receptor-specific endosomal route. This resulted in accumulation of the reporter nanoparticle in a fully fluorescent and stable form in the perinuclear region of the target cells, without toxicity either in cell culture or in an in vivo model of metastatic colorectal cancer. Given the urgent demand for targeting agents in the research, diagnosis, and treatment of CXCR4-linked diseases, including colorectal cancer and human immunodeficiency virus infection, T22 appears to be a promising tag for the intracellular delivery of protein drugs, nanoparticles, and imaging agents

Sheltering DNA in self-organizing, protein-only nano-shells as artificial viruses for gene delivery

By recruiting functional domains supporting DNA condensation, cell binding, internalization, endosomal escape and nuclear transport, modular single-chain polypeptides can be tailored to associate with cargo DNA for cell-targeted gene therapy. Recently, an emerging architectonic principle at the nanoscale has permitted tagging protein monomers for self-organization as protein-only nanoparticles. We have studied here the accommodation of plasmid DNA into protein nanoparticles assembled with the synergistic assistance of end terminal poly-arginines (R9) and poly-histidines (H6). Data indicate a virus-like organization of the complexes, in which a DNA core is surrounded by a solvent-exposed protein layer. This finding validates end-terminal cationic peptides as pleiotropic tags in protein building blocks for the mimicry of viral architecture in artificial viruses, representing a promising alternative to the conventional use of viruses and virus-like particles for nanomedicine and gene therapy

ApoA-I Milano stimulates lipolysis in adipose cells independently of cAMP/PKA activation.

ApoA-I, the main protein component of high-density lipoprotein (HDL), is suggested to be involved in metabolic homeostasis. We examined the effects of Milano, a naturally occurring ApoA-I variant, about which little mechanistic information is available. Remarkably, high fat-fed mice treated with Milano displayed a rapid weight loss greater than ApoA-I WT treated mice, and a significantly reduced adipose tissue mass, without an inflammatory response. Further, lipolysis in adipose cells isolated from mice treated with either WT or Milano was increased. In primary rat adipose cells, Milano stimulated cholesterol efflux and increased glycerol release, independently of β-adrenergic stimulation and phosphorylation of hormone sensitive lipase (Ser563) and perilipin (Ser522). Stimulation with Milano had a significantly greater effect on glycerol release compared with WT but similar effect on cholesterol efflux. Pharmacological inhibition or siRNA silencing of ABCA-1 did not diminish Milano-stimulated lipolysis, although binding to the cell surface was decreased, as analyzed by fluorescence microscopy. Interestingly, methyl-β-cyclodextrin, a well-described cholesterol acceptor, dose-dependently stimulated lipolysis. Together, these results suggest that decreased fat mass and increased lipolysis following Milano treatment in vivo is partly explained by a novel mechanism at the adipose cell level comprising stimulation of lipolysis independently of the canonical cAMP/PKA signaling pathway

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)