Browsing by Subject "microfluidics"

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  • Wannasarit, Saowanee; Wang, Shiqi; Figueiredo, Patricia; Trujillo Olvera, Claudia Ximenia; Eburnea, Francesca; Simón-Gracia, Lorena; Correia, Alexandra; Ding, Yaping; Teesalu, Tambet; Liu, Dongfei; Wiwattanapatapee, Ruedeekorn; Santos, Hélder A.; Li, Wei (2019)
    Achieving cellular internalization and endosomal escape remains a major challenge for many antitumor therapeutics, especially macromolecular drugs. Viral drug carriers are reported for efficient intracellular delivery, but with limited choices of payloads. In this study, a novel polymeric nanoparticle (ADMAP) is developed, resembling the structure and functional features of a virus. ADMAP is synthesized by grafting endosomolytic poly(lauryl methacrylate‐co‐methacrylic acid) on acetalated dextran. The endosomolytic polymer mimics the capsid protein for endosomal escape, and acetalated dextran resembles the viral core for accommodating payloads. After polymer synthesis, the subsequent controlled nanoprecipitation on a microfluidic device yields uniform nanoparticles with high encapsulation efficiency. At late endosomal pH (5.0), the ADMAP particles successfully destabilize endosomal membranes and release the drug payloads synergistically, resulting in a greater therapeutic efficacy compared with that of free anticancer drugs. Further conjugation of a tumor‐penetrating peptide enhances the antitumor efficacy toward 3D spheroids and finally leads to spheroid disintegration. The unique structure along with the synergistic endosomal escape and drug release make ADMAP nanoparticles favorable for intracellular delivery of antitumor therapeutics.
  • Fontana, Flavia; Fusciello, Manlio; Groeneveldt, Christianne; Capasso, Cristian; Chiaro, Jacopo; Feola, Sara; Liu, Zehua; Mäkilä, Ermei; Salonen, Jarno; Hirvonen, Jouni; Cerullo, Vincenzo; Santos, Hélder A. (2019)
    Recent approaches in the treatment of cancer focus on involving the immune system to control the tumor growth. The administration of immunotherapies, like checkpoint inhibitors, has shown impressive results in the long term survival of patients. Cancer vaccines are being investigated as further tools to prime tumor-specific immunity. Biomaterials show potential as adjuvants in the formulation of vaccines, and biomimetic elements derived from the membrane of tumor cells may widen the range of antigens contained in the vaccine. Here, we show how mice presenting an aggressive melanoma tumor model treated twice with the complete nanovaccine formulation showed control on the tumor progression, while in a less aggressive model, the animals showed remission and control on the tumor progression, with a modification in the immunological profile of the tumor microenvironment. We also prove that co-administration of the nanovaccine together with a checkpoint inhibitor increases the efficacy of the treatment (87.5% of the animals responding, with 2 remissions) compared to the checkpoint inhibitor alone in the B16.OVA model. Our platform thereby shows potential applications as a cancer nanovaccine in combination with the standard clinical care treatment for melanoma cancers.
  • Kiiski, Iiro; Ollikainen, Elisa; Artes, Sanna; Järvinen, Päivi; Jokinen, Ville; Sikanen, Tiina (2021)
    UDP-glucuronosyltransferases (UGTs), located in the endoplasmic reticulum of liver cells, are an important family of enzymes, responsible for the biotransformation of several endogenous and exogenous chemicals, including therapeutic drugs. However, the phenomenon of 'latency', i.e., full UGT activity revealed by disruption of the microsomal membrane, poses substantial challenges for predicting drug clearance based on in vitro glucuronidation assays. This work introduces a microfluidic reactor design comprising immobilized human liver microsomes to facilitate the study of UGT-mediated drug clearance under flow-through conditions. The performance of the microreactor is characterized using glucuronidation of 8-hydroxyquinoline (via multiple UGTs) and zidovudine (via UGT2B7) as the model reactions. With the help of alamethicin and albumin effects, we show that conducting UGT metabolism assays under flow conditions facilitates in-depth mechanistic studies, which may also shed light on UGT latency.
  • Pihlaja, Tea (Helsingfors universitet, 2017)
    Cytochrome P450 (CYP) enzymes are important catalysers in the first phase of drug metabolism. Roughly two thirds of drugs are oxidized via CYP enzymes, which enable the further modification of drugs, and their excretion. In this thesis, human liver microsomes containing the main hepatic CYP enzymes were immobilized on thiol-ene based micropillar arrays and their stability was evaluated using a CYP2C9 isoenzyme specific luminescent substrate, Luciferin-H. The aim of the study was to develop microfluidic immobilized enzyme reactors (IMERs) for studying enzyme kinetics and drug-drug interactions. For this purpose, the instability issues associated with previously reported CYP-IMERs were carefully addressed. The CYP immobilization protocol used was based on a protocol previously developed in the context of other research projects and relied on biotinylation of human liver microsomes (HLM) with help of fusogenic liposomes. The biotinylated HLMs were then attached to the streptavidin-modified thiol-ene surfaces. The CYP activity was determined by utilizing microfluidics under continuous flow conditions (typically 5 μL/min) in the presence of NADPH. The luminescent metabolite formed by the CYP2C9 enzymes was quantified with a commercial well-plate reader from fractions collected at the microreactor outlet. Half-life was used to compare the differences between enzyme stabilities reached via different immobilization conditions. The effects of flow rate and reaction temperature on the stability of the CYP-IMERs was evaluated together with addition of antioxidative agents and reactive oxygen species (ROS) scavengers. Different functionalization steps as well as storage time and conditions were studied. With Luciferin-H as the model substrate of CYP2C9, the CYP-IMERs showed higher activity and stability at room temperature than at +37 °C. The peak activity could be increased via optimization of the immobilization protocol, though long-term storage diminished the peak activity. The activity of the IMERs typically attenuated within 1-2 hours with little or no improvement achieved via optimization of the immobilization or operation conditions. Only upon addition of the ROS scavengers, the peak activity and stability of the CYP-IMERs could be slightly improved. After functionalization, the IMERs maintained their activity until the time of use when stored in +4 °C for up to 2 weeks, but re-use of IMERs was not possible.
  • Wang, Shiqi; Wannasarit, Saowanee; Figueiredo, Patricia; Molinaro, Giuseppina; Ding, Yaping; Correia, Alexandra; Casettari, Luca; Wiwattanapatapee, Ruedeekorn; Hirvonen, Jouni; Liu, Dongfei; Li, Wei; Santos, Hélder A. (2021)
    In this study, a rationally designed nanocomposite (BUDPDA@MAP) composed of polydopamine (PDA) nanoparticle and anti‐inflammatory drug budesonide (BUD) encapsulated in a pH‐responsive endosomolytic polymer (poly(butyl methacrylate‐co‐methacrylic acid) grafted acetalated dextran, denoted by MAP), is proposed. The uniform nanocomposite is prepared using a microfluidic device. At low endosomal pH (5.5), MAP destabilizes the endosomal membranes for the cytoplasmic delivery of PDA, and releases BUD simultaneously, resulting in a greater reactive oxygen species scavenging capability than both the free drug and PDA alone. The combined therapeutic efficacy from PDA and BUD also leads to a successful macrophage phenotype switch from pro‐inflammatory M1 to anti‐inflammatory M2.
  • Singh, Akanksha; Scotti, Gianmario; Sikanen, Tiina; Jokinen, Ville; Franssila, Sami (2014)
  • Hemmila, Samu; Ruponen, Marika; Toropainen, Elisa; Tengvall-Unadike, Unni; Urtti, Arto; Kallio, Pasi (2020)
    This paper presents a novel microflow-based concept for studying the permeability of in vitro cell models or ex vivo tissues. Using the proposed concept, we demonstrate how to maintain physiologically relevant test conditions and produce highly reproducible permeability values for a range (31) of drug compounds. The apparent permeability coefficients (P-app) showed excellent correlation (0.89) with the values from experiments performed with a conventional Ussing chamber. Additionally, the microflow-based concept produces notably more concentrated samples than the conventional Ussing chamber-based approach, despite the fact that more than 10 times smaller quantities of test compounds and biological membranes are needed in the microflow-based concept.
  • Sikanen, Tiina; Kiiski, Iiro; Ollikainen, Elisa (John Wiley & Sons Ltd., 2021)
    Advances in Pharmaceutical Technology
    This chapter reviews the evolution of microfabrication methods and materials, applicable to manufacturing of micro total analysis systems (or lab‐on‐a‐chip), from a general perspective. It discusses the possibilities and limitations associated with microfluidic cell culturing, or so called organ‐on‐a‐chip technology, together with selected examples of their exploitation to characterization of pharmaceutical nano‐ and microsystems. Materials selection plays a pivotal role in terms of ensuring the cell adhesion and viability as well as defining the prevailing culture conditions inside the microfluidic channels. The chapter focuses on the hepatic safety assessment of nanoparticles and gives an overview of the development of microfluidic immobilized enzyme reactors that could facilitate examination of the hepatic effects of nanomedicines under physiologically relevant conditions. It also provides an overview of the future prospects regarding system‐level integration possibilities facilitated by microfabrication of miniaturized separation and sample preparation systems as integral parts of microfluidic in vitro models.
  • Pessi, Jenni (Helsingfors universitet, 2013)
    Polymer microspheres hold great potential as oral drug delivery system for therapeutic proteins. Microspheres prepared with biocompatible and biodegredable polymers have been extensively studied, since the oral delivery of therapeutic proteins is challenging due to the conditions in the GI-tract. The aims of this research were to apply microfluidics on polymeric microsphere preparation process, to determine what kind of formulations are suitable for this technology, to establish a controlled preparation process that produces advanced particles and to create a template for oral protein drug delivery. With microfluidic fabrication it is possible to gain control over the process and content of each droplet. However, finding suitable formulations for microfluidics is demanding. In this study, biphasic flow was employed to successfully produce double (W/O/W) emulsion droplets with ultra thin shells. Once the process and formulation variables were optimized constant droplet production was achieved. Flow rates used were 500 µl/h in the inner and in the middle phase and 2500 µl/h in the outer phase, respectively. Two formulations were selected for further characterization: 5 % poly(vinyl alcohol) in water in the outer phase, 3 % polycaprolactone in ethyl acetate in the middle phase and either 10 % or 20 % poly(vinyl alcohol) and polyethylenglycol (1:4) in water in the inner phase. All the particles were found to be intact and contain the inner phase, as verified by confocal microscopy. Further, the particles were monodisperse and non-porous, as observed by scanning electron microscopy. Particle size was found to be around 20-40 µm, variation in the particle size within one batch was small and the particles were stable up to 4 weeks. The encapsulation efficiency of the particles was remarkable; as high as 85 % loading of the model compound, bovine serum albumin. Particles released 30 % of their content within 48 hours. In conlusion, developing functional formulations for micfoluidic technology was possible, the microparticles encapsulated the model protein extremely well and all in all microfluidic technology had a lot of potential for droplet manufacturing for pharmaceutical applications.
  • Liu, Zehua; Fontana, Flavia; Python, Andre; Hirvonen, Jouni T.; Santos, Helder A. (2020)
    In the past two decades, microfluidics-based particle production is widely applied for multiple biological usages. Compared to conventional bulk methods, microfluidic-assisted particle production shows significant advantages, such as narrower particle size distribution, higher reproducibility, improved encapsulation efficiency, and enhanced scaling-up potency. Herein, an overview of the recent progress of the microfluidics technology for nano-, microparticles or droplet fabrication, and their biological applications is provided. For both nano-, microparticles/droplets, the previously established mechanisms behind particle production via microfluidics and some typical examples during the past five years are discussed. The emerging interdisciplinary technologies based on microfluidics that have produced microparticles or droplets for cellular analysis and artificial cells fabrication are summarized. The potential drawbacks and future perspectives are also briefly discussed.
  • Lifländer, Rami (Helsingin yliopisto, 2020)
    Throughout the history, there has been a wide selection of drugs developed for therapy of cardiovascular diseases (CVD). Despite a broad spectrum of different therapeutic strategies to deaccelerate and try to reverse the progression of cardiovascular diseases has been achieved, only a modest amelioration of the health of the CVD patients was achieved, as the mortality remains high by being the cause of nearly one in every three deaths yearly, myocardial infarction being involved in majority of these cases. Novel solutions are being studied to overcome this problem, one of them being nanoparticles, which may provide potential solution by carrying drugs to the desired location. Microfluidics technique may further improve the properties of nanoparticles, being a platform that allows the production of homogenous and repeatable batches that are non-dependent by the operator using it. In this thesis, it is described how microfluidics-based preparation of spermine-functionalised acetalated dextran nanoparticles co-loaded with a trisubstituted isoxazole and curcumin perform in physicochemical and in vitro experiments, in order to evaluate their potential in the application of ischemic myocardial injury therapy.
  • Peuraniemi, Tuukka (Helsingfors universitet, 2012)
    The aim of this research was to evaluate the use of microfluidic paper-based devices (µPAD) in drug analysis. Micro total analysis systems (µTAS) channels are in the range of a few micrometers and are capable of performing all steps of a chemical analysis. The advantages of miniaturization are lower sample consumption and faster analysis time. µTASs are usually fabricated of glass, silicon or polymers and their fabrication requires cleanroom facilities and specific equipment. Paper offers an inexpensive and versatile substrate for µTASs. Paper wicks liquids and no external pumps are required. µPADs advantages over µTAS are its ease of use and inexpensive and simple fabrication. µPADs are fabricated by patterning hydrophobic barriers in hydrophilic paper. There are several fabrication methods for µPADs such as photolithography, cutting and methods based on the application of wax (etching, wax printing, wax dipping). In this research wax printing was selected as the fabrication method because it's simple, rapid and inexpensive. Wax was printed using Xerox Phaser 8560DN solid ink printer. After printing the wax was melted through the paper by heating the paper at 150 °C for 120 seconds on a hotplate. Thus the wax creates a hydrophobic barrier on the hydrophilic paper which channels the liquids flow. Owing to papers anisotropic nature the wax also spreads horizontally in the paper when heated, thus reducing the wax patterns resolution and making the pattern coarse. Wax printing is an inexpensive and simple fabrication method suitable for fabricating µPADs. Also liquids flow velocity and methods for controlling the flow rate were studied. By knowing the flow velocity, one can assure that the analytes and reagents reach the reaction site. Controlling the flow velocity enables the use of multiphase reactions or the use of multiple simultaneous reactions on the µPAD. The liquid flow velocity can be controlled by changing the hydrophilic channels width, reducing the average pore size by melting a layer of wax inside the hydrophilic channel or by changing the surface tension or viscosity of the liquid used. Colorimetric assays are the most commonly used detection methods in µPADs, but also electrochemical sensing and detection methods based on fluorescence are used. In this study direct and indirect fluorescence detection methods were studied. In the detection method based on direct fluorescence, fluorescein and coumarine derivates were studied. In indirect fluorescence amino acids fluorescamine conjugates, which were created in the paper, were studied. Level of the analytes detected in direct fluorescence detection was 10-13 mol in the range of visible light and 10-12 mol in the range of UV-light. Level of the amino acids fluorescamine conjugates detected in indirect fluorescence detection was 10-9 mol. According to our results the fluorescence based detection methods used in this study are suitable for drug analysis on µPADs.
  • Fontana, Flavia; Martins, Joao P.; Torrieri, Giulia; Santos, Helder A. (2019)
    Nanotechnology holds the promise of bringing revolutionary therapeutic strategies into the clinic. However, an enormous fraction of the currently proposed nanotechnology-based therapies suffers from lack of reproducibility, complexity, high costs, and scale-up-related issues. For these reasons, the research community is moving toward the miniaturization of biomaterials and fabrication methods. Customizable microfluidic-based products have gained tremendous relevance in the development of biomedical technologies. This review provides an overview of different materials that can be used for the fabrication of microfluidic devices, as well as the other parameters influencing the production of biomaterials and biosensors. Moreover, several advanced microfluidic-based technologies that are designed to overcome the current challenges of cancer, immunotherapy, and diabetes therapy, among others are described. Then, the pros and cons of microfluidics as alternative to conventional preparation methods, and the challenges of translating this technique to an industrial context are highlighted. Overall, microfluidic technologies and their accessibility to the research community offer a set of exciting opportunities to bridge the development of innovative therapies and their commercialization in the foreseeable future.
  • Bobik, Nina (Helsingin yliopisto, 2022)
    Despite recent advances in immunotherapies for lung cancer, their success is still hindered by limited predictability of treatment outcomes in patients, as well as by resistance-conveying tumor mutations such as EGFR. Moreover, due to the vast number of treatment options and their cost, a quick, reliable, and cost-efficient drug screening platform is needed to select the optimal treatments for each individual patient. This thesis focuses on finding the best culture conditions to be used in such a future platform, employing 3D cell cultures and microfluidics to mimic in vivo tumors while saving costs and allowing for high-throughput screening. Image-based analysis showed that culture medium can have significant impacts on both cancer organoid growth and morphology, as well as drug sensitivity to the EGFR-inhibiting drug Osimertinib. Specific medium factors, such as the antioxidant N-acetylcysteine, might be particularly important for the integrity of 3D structures in the platform and help prevent conversion to an adherent morphology. Moreover, flow cytometry analysis of immune cells from pleural effusion samples indicated that medium composition might facilitate creating an inflammatory environment in the platform, and that immune cells should not be cultured longer than one week to maximize their activity. Finally, this thesis compares two microfluidic devices for their suitability to be used in future high-throughput drug-screening applications, by contrasting their ease of handling, applicability in fluorescent imaging-based readouts, and possibility to mimic and study the tumor microenvironment in vitro. The results suggest that the choice of microfluidic device will be dependent on whether microscopy analysis or cell viability assays will be used as the main readout of the drug screening in the future.
  • Feola, Sara; Haapala, Markus; Peltonen, Karita; Capasso, Cristian; Martins, Beatriz; Antignani, Gabriella; Federico, Antonio; Pietiäinen, Vilja; Chiaro, Jacopo; Feodoroff, Michaela; Russo, Salvatore; Rannikko, Antti; Fusciello, Manlio; Koskela, Satu; Partanen, Jukka; Hamdan, Firas; Tähkä, Sari M.; Ylösmäki, Erkko; Greco, Dario; Grönholm, Mikaela; Kekarainen, Tuija; Eshaghi, Masoumeh; Gurvich, Olga L.; Ylä-Herttuala, Seppo; Branca, Rui M. M.; Lehtiö, Janne; Sikanen, Tiina M.; Cerullo, Vincenzo (2021)
    Identification of HLA class I ligands from the tumor surface (ligandome or immunopeptidome) is essential for designing T-cell mediated cancer therapeutic approaches. However, the sensitivity of the process for isolating MHC-I restricted tumor-specific peptides has been the major limiting factor for reliable tumor antigen characterization, making clear the need for technical improvement. Here, we describe our work from the fabrication and development of a microfluidic-based chip (PeptiCHIP) and its use to identify and characterize tumor-specific ligands on clinically relevant human samples. Specifically, we assessed the potential of immobilizing a pan-HLA antibody on solid surfaces via well-characterized streptavidin-biotin chemistry, overcoming the limitations of the cross-linking chemistry used to prepare the affinity matrix with the desired antibodies in the immunopeptidomics workflow. Furthermore, to address the restrictions related to the handling and the limited availability of tumor samples, we further developed the concept toward the implementation of a microfluidic through-flow system. Thus, the biotinylated pan-HLA antibody was immobilized on streptavidin-functionalized surfaces, and immune-affinity purification (IP) was carried out on customized microfluidic pillar arrays made of thiol-ene polymer. Compared to the standard methods reported in the field, our methodology reduces the amount of antibody and the time required for peptide isolation. In this work, we carefully examined the specificity and robustness of our customized technology for immunopeptidomics workflows. We tested this platform by immunopurifying HLA-I complexes from 1 × 106 cells both in a widely studied B-cell line and in patients-derived ex vivo cell cultures, instead of 5 × 108 cells as required in the current technology. After the final elution in mild acid, HLA-I-presented peptides were identified by tandem mass spectrometry and further investigated by in vitro methods. These results highlight the potential to exploit microfluidics-based strategies in immunopeptidomics platforms and in personalized immunopeptidome analysis from cells isolated from individual tumor biopsies to design tailored cancer therapeutic vaccines. Moreover, the possibility to integrate multiple identical units on a single chip further improves the throughput and multiplexing of these assays with a view to clinical needs.
  • Liu, Zehua; Lian, Wenhua; Long, Qiang; Cheng, Ruoyu; Torrieri, Giulia; Zhang, Baoding; Koivuniemi, Artturi; Mahmoudzadeh, Mohammad; Bunker, Alex; Gao, Han; He, Hongbin; Chen, Yun; Hirvonen, Jouni; Zhou, Rongbin; Zhao, Qiang; Ye, Xiaofeng; Deng, Xianming; Santos, Helder A. (2022)
    Nanoparticle (NP)-based intravenous administration represents the most convenient cardiac targeting delivery routine, yet, there are still therapeutic issues due to the lack of targeting efficiency and specificity. Active targeting methods using functionalization of ligands onto the NPs' surface may be limited by trivial modification procedures and reduced targeting yield in vivo. Here, a microfluidics assisted single step, green synthesis method is introduced for producing targeting ligands free heart homing NPs in a tailored manner. The generated beta-glucan-based NPs exhibit precise and efficient targeting capability toward Dectin-1(+) monocytes/macrophages, which are confirmed as main pathogenesis mediators for cardiac ischemic/reperfusion (I/R) injury, with a sequentially enhanced cardiac NP accumulation, and this targeting strategy is exclusively suitable for cardiac I/R but not for other cardiovascular diseases, as confirmed both in murine and human model. Comparing to FDA-approved nano-micelles formulation, beta-glucan NPs loaded with NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome inhibitor (CY-09) exhibit better efficiency in ameliorating myocardial injury and heart failure induced by surgically induced I/R. These findings indicate a simple production of targeting-ligand free NPs, and demonstrate their potential therapeutic applications for preclinical I/R-induced cardiac injury amelioration.
  • Tatikonda, Anand; Jokinen, Ville P.; Evard, Hanno; Franssila, Sami (2018)
    The low fabrication cost of SU-8-based devices has opened the fields of point-of-care devices (POC), mu TAS and Lab-on-Chip technologies, which call for cheap and disposable devices. Often this translates to free-standing, suspended devices and a reusable carrier wafer. This necessitates a sacrificial layer to release the devices from the substrates. Both inorganic (metals and oxides) and organic materials (polymers) have been used as sacrificial materials, but they fall short for fabrication and releasing multilayer SU-8 devices. We propose photoresist AZ 15nXT (MicroChemicals GmbH, Ulm, Germany) to be used as a sacrificial layer. AZ 15nXT is stable during SU-8 processing, making it suitable for fabricating free-standing multilayer devices. We show two methods for cross-linking AZ 15nXT for stable sacrificial layers and three routes for sacrificial release of the multilayer SU-8 devices. We demonstrate the capability of our release processes by fabrication of a three-layer free-standing microfluidic electrospray ionization (ESI) chip and a free-standing multilayer device with electrodes in a microchannel.
  • Teppo, Jaakko (Helsingfors universitet, 2015)
    The properties of liquid and gas flows in microscale systems differ from those in macroscale; microfluidics is a field of science in which these properties are investigated and utilized for the development of microscale systems. Acoustofluidics is a branch of microfluidics focusing on the movement (acoustophoresis) or localization (acoustic trapping) of particles in microchannels using ultrasound. In this work, the suitability of a new miniaturized method for the screening of cell-drug interactions was investigated. In the method, the cells were acoustically trapped within a glass capillary, enabling liquid movement (generated with a syringe pump) in the capillary while the trapped cell cluster remains stationary. In this manner, the trapping of cells, their incubation with a drug solution, rinsing, and the elution could be done using the same capillary. The sample preparation was done using a miniaturized solid phase extraction technique (integrated selective enrichment target, ISET), and the analysis was done with matrix assisted laser desorption/ionization mass spectrometry (MALDI MS). The drug compounds investigated were selective serotonin reuptake inhibitors (SSRI). The research was conducted in five phases. In the first phase, a suitable solid phase extraction method for the drug compounds was investigated. In the second phase, the performance of the acoustic trap was investigated by acoustically trapping polystyrene beads and Coulter counting them. In the third phase, the method was modelled by conducting drug binding studies using cation exchange beads instead of cells. In the fourth phase, the drug binding studies were conducted by investigating the binding of drug compounds to human platelets and yeast cells. Platelets were chosen due to the expression of serotonin transporter, the molecular target of SSRI drugs, on their cell membranes. Also a cell membrane preparation containing serotonin transporter was used for the binding studies. In addition, memory effects occurring in the method were investigated. In the fifth phase, comparative drug binding studies without acoustic trapping were conducted. The suitability of the method for the screening of cell-drug interactions could not be thoroughly substantiated, but further research and method development are required. The reason for this was the inadequate sensitivity of the method, because of which large drug concentrations had to be used. This lead to the increased occurrence of memory effects.
  • Järvinen, Päivi; Bonabi, Ashkan; Jokinen, Ville; Sikanen, Tiina (2020)
    Two‐dimensional (2D) cell cultures have been the primary screening tools to predict drug impacts in vitro for decades. However, owing to the lack of tissue‐specific architecture of 2D cultures, secondary screening using three‐dimensional (3D) cell culture models is often necessary. A microfluidic approach that facilitates side‐by‐side 2D and 3D cell culturing in a single microchannel and thus combines the benefits of both set‐ups in drug screening; that is, the uniform spatiotemporal distributions of oxygen, nutrients, and metabolic wastes in 2D, and the tissue‐like architecture, cell–cell, and cell–extracellular matrix interactions only achieved in 3D. The microfluidic platform is made from an organically modified ceramic material, which is inherently biocompatible and supports cell adhesion (2D culture) and metal adhesion (for integration of impedance electrodes to monitor cell proliferation). To induce 3D spheroid formation on another area, a single‐step lithography process is used to fabricate concave microwells, which are made cell‐repellant by nanofunctionalization (i.e., plasma porosification and hydrophobic coating). Thanks to the concave shape of the microwells, the spheroids produced on‐chip can also be released, with the help of microfluidic flow, for further off‐chip characterization after culturing. In this study, the methodology is evaluated for drug cytotoxicity assessment on human hepatocytes.
  • Flinck, Tapio (Helsingin yliopisto, 2020)
    Pään ja kaulan alueen syövät ovat kuudenneksi yleisin syöpäryhmä maailmanlaajuisesti. Suun levyepiteelikarsinooma (OSCC) on yleisin suuontelossa esiintyvä syöpä. OSCC on suhteellisen heikkoennusteinen ja sen takia aikainen diagnoosi ja hoito ovat erityisen tärkeitä. Hoidot ovat potilaalle usein raskaat ja saattavat jättää pysyviä haittoja, kuten sylkirauhasten toiminnan heikkenemistä. Uusien syöpähoitojen ja diagnostiikkaa helpottavien menetelmien tutkiminen on tärkeää siitäkin näkökulmasta, että tilastojen mukaan suusyöpätapausten määrä on Suomessa ja muuallakin maailmalla jatkuvassa kasvussa. Tämän syventävän opintojen tutkielman tarkoituksena oli syventyä suusyövän kokeellisiin mallintamismenetelmiin ja menetelmien eri ominaisuuksiin. Lisäksi tarkoituksena oli tutkia mikrosirun avulla eri immuunimodulaattorien vaikutusta valkosolujen migraatioon. Aikaisemmassa mikrosirumallissa tutkimusryhmä oli osoittanut IDO-1 reseptori-inhibiittorin lisäävän T-valkosolujen vaellusta kohti HSC-3 kielisyöpäsoluja. Kokeellisessa osuudessa testattiin uuden sirumallin soveltuvuutta koettamme varten, aluksi väriaineen avulla. Testauksessa havaittiin, että uusi sirumalli ei toiminut toivotulla tavalla: väriaine ei päässyt diffundoitumaan vapaasti kammiosta toiseen. Soluilla testattaessa huomattiin, että kammiot olivat liian suuret ja että T-tappajasolut eivät saavuttaneet syöpäsoluja toisessa kammiossa. Käytettyä sirua tulee vielä muokata, jotta testi onnistuisi soluilla halutulla tavalla. Vaihtoehtoja on kaksi: kammioiden pienentäminen ja muokkaaminen siten, että syöpäsolut ovat lähempänä mikroputkia, tai solujen kasvumediumin vaihtamisen mahdollistaminen kokeen aikana.