RESEARCH Drug Delivery and Nanotechnology Transdermal Drug Delivery Arto Urtti, Ph.D, ProfessorArto Urtti, Ph.D, Professor
Transdermal Drug Delivery
Selected Publications:
- Organotypic cell cultures and two-photon imaging: tools for in vitro and in vivo assessment of percutaneous drug delivery and skin toxicity. Pappinen S, Pryazhnikov E, Khiroug L, Ericson MB, Yliperttula M, Urtti A. J Control Release. 2012 Jul 20;161(2):656-67.
- Comparison of rat epidermal keratinocyte organotypic culture (ROC) with intact human skin: lipid composition and thermal phase behavior of the stratum corneum. Pappinen S, Hermansson M, Kuntsche J, Somerharju P, Wertz P, Urtti A, Suhonen M. Biochim Biophys Acta. 2008 Apr;1778(4):824-34.
- Rat epidermal keratinocyte organotypic culture (ROC) compared to human cadaver skin: the effect of skin permeation enhancers. Pappinen S, Tikkinen S, Pasonen-Seppänen S, Murtomäki L, Suhonen M, Urtti A. Eur J Pharm Sci. 2007 Mar;30(3-4):240-50.
- Epidermal cell culture model with tight stratum corneum as a tool for dermal gene delivery studies. Paasonen L, Korhonen M, Yliperttula M, Urtti A. Int J Pharm. 2006 Jan 13;307(2):188-93.
- Epidermal cell culture model derived from rat keratinocytes with permeability characteristics comparable to human cadaver skin. Marjukka Suhonen T, Pasonen-Seppänen S, Kirjavainen M, Tammi M, Tammi R, Urtti A. Eur J Pharm Sci. 2003 Sep;20(1):107-13.
Research-oriented program for M.Sc. students in Pharmacy
Cellular and Computational ADME Drug Discovery Tools
Cellular and computational models are developed for improved prediction of clinical ADME properties. We are using and further developing the following epithelial cell models: Caco-2, MDCK, MDCK cell lines with transfected human transporter genes, blood-retinal barrier models, corneal and epidermal models. Furthermore, we have generated numerous Sf9 cells that stably express various human ABS efflux transporters. These cell models can be used for drug permeability and transporter interaction studies. Computational modeling activities can be divided into two categories: structure-based models and pharmacokinetic models. Structure-based models include QSAR for oral drug absorption. QSAR models for efflux transport and volume of drug distribution are being developed and tested continuously. Both in vitro and in silico data are integrated into pharmacokinetic simulation models that can be used to estimate the importance of different factors in the physiological setting.
Complex Organotypic Cell Models
Microencapsulated cells may ultimately enable even permanent protein drug therapy with a single administration. Retinal pigment epithelial cell lines (ARPE-19) were cloned to secrete marker protein as well as soluble VEGF-receptor that acts by sequestering free VEGF from tissues. The net effect is to block VEGF activity. We microencapsulated these cells and demonstrated prolonged protein secretion from them (3, 4). This cell therapy research resulted in development and production of a laboratory scale cell microencapsulation device (4) as well as a demonstration of proof-of-principle that cell viability could be preserved in microcapsules during freeze-drying (5). Such methods could facilitate the future logistics for use of polymer-embedded cell therapy products.
Selected Publications:
1. Nanofibrillar cellulose hydrogel promotes three-dimensional liver cell culture. M Bhattacharya, M Malinen, P Lauren, YR Lou, C Parras-Cicuendez , S Kuisma, L Kanninen, M Lille, A Corlu, C Guillozo, A Laukkanen, A Urtti, M Yliperttula. J Control Release, in press.
2. Peptide nanofiber hydrogel induces formation of bile canalicular structures in 3D cultures of hepatic cell line. M. Malinen, H. Palokangas, M. Yliperttula, A. Urtti. Tissue Engineering Part A, in press.
Nanocarriers and Drug Delivery
Biomaterials are useful in drug delivery and targeting, since they can be optimized as controlled release formulations and also as nanoparticles for intracellular drug delivery. Our unique interdisciplinary research program couples both physico-chemical and biological aspects in this area. The research is focused in particular on continuous protein delivery from microencapsulated cells and on nanoparticle-mediated gene delivery and targeted anti-cancer drug research.
Selected Publications:
Ocular Drug Delivery and ADME
Ocular drug delivery is a limiting factor in the development of new medications to the treat diseases of the posterior eye segment. Research on delivery systems, test models and computational models opens avenues for improved ocular drug treatments. Our group has more than 20 years of experience in ocular drug delivery including: cell model development, drug discovery, drug formulation, kinetic modeling, and basic cell research of the eye. The research group is multidisciplinary including expertise in pharmaceutical sciences, molecular and cell biology, materials science, bio-organic chemistry, physical chemistry, and molecular modeling.
We characterized an immortalized human corneal epithelium cell model (HCE) for ocular absorption studies. The physical barrier properties and the relevance of this cell model were established earlier. However, the efflux transporters and monocarboxylic acid transporters in the model showed different expression profiles compared to human corneal epithelium (3, 4). Universal expression analysis with DNA arrays (aaproximately 11,000 genes) was performed on HCE cell model and human corneal epithelium (5). The expression profiles were strikingly different demonstrating the power of systems biology approaches in the evaluation of ADME cell models and the limitations of the HCE model.
We have generated a series of baculovirus-infected insect cells for selective over-expression of efflux proteins MRP-2, MRP-4, MDR-1, and BCRP. The systems are used to investigate the efflux protein interactions of chemical libraries. The goal is to make QSPR models of these interactions. We performed experiments with MRP-2 overexpressing cells, and the modeling is under way. We have also demonstrated that various assays yield different conclusions on drug interactions with MRP-2 (6). Furthermore, we showed that the corneal epithelium and RPE (anterior and posterior ocular barriers) express MRP-1, MRP-4 and MRP-5 (3, 7). This profile is different from many other barriers. The PK importance of these transporters in the eye remains to be discovered.
Ocular ADME modeling is an important tool in understanding the relationships between molecular structure and PK properties in the eye. Along these lines, we have carried out modeling of all existing and curated data on corneal drug permeability (describes ocular absorption) and half-life in vitreous (describes elimination and distribution in the posterior eye segment). In both cases, we were able to generate a reliable model with only two chemical descriptors (8, 9). These models are useful tools in estimating the PK behavior of ocular compounds early in drug discovery.
Sub-conjunctival administration is an interesting alternative to more invasive intravitreal ocular injections, but yet this route is poorly understood. We built the first PK simulation model that includes all relevant parameters (elimination from subconjunctival site to blood and lymphatic flow, scleral permeability, choroidal elimination to blood flow, RPE permeability and vitreal elimination). The simulations show that, eventually, high molecular weight is beneficial for drug delivery. Large molecules are lost to blood flow slower than small compounds, and this factor is more important than the permeability advantage of small molecules (10). The model also provides insights on strategies for posterior segment drug delivery.
Selected Publications:
Drug Delivery and Nanotechnology
Drug delivery is an essential part of pharmaceutical sciences that should be taken into account early in the drug discovery and development process. A drug that cannot be delivered to its site of action is essentially useless. Drug delivery is affected by the physico-chemical properties of the drug and formulation and the interplay of these factors with the transport, binding, and metabolism of the drug in the body. New tools are needed to accurately predict delivery properties of the compounds early during drug discovery, so that the best compounds can be identified for clinical studies. Another class of tools includes the delivery methods that facilitate delivery of hard-to-deliver compounds to the appropriate target sites. Delivery of gene-based drugs (DNA, oligonucleotides, siRNA) and proteins is a major challenge in pharmaceutical science. Nanotechnology can be used to improve drug delivery in these difficult cases. The development and use of nanoparticles in the formulation of these types of drugs is a major focus at CDR, and we welcome productive industrial partnerships to develop these tools for translational use.
Ocular Drug Delivery and ADME — Treatment of retinal diseases (e.g., age-related macular degeneration, glaucoma, diabetic retinopathy) is hampered by ineffective and/or short-acting drug delivery to the target cells. Eye drop instillation results in negligible (0.001%) bioavailability in the retina. Intravitreal injections deliver drug to the retina, but this is rarely feasible, because vitreal half-lives of most drugs are below 10 hours. Periocular (sub-tenon, subconjunctival), subretinal and suprachoroidal routes of drug administration are potentially useful, but again, efficacy and/or duration of action are not adequate. Minimally invasive, long acting, and effective drug delivery would be a major breakthrough in ophthalmic drug treatment. Development of improved delivery systems requires proper understanding of ocular pharmacokinetics and construction of the delivery systems. Surprisingly, the expression and activity of drug transporters in the eye is poorly understood. Further, the QSPR of drugs’ ADME properties in the eye have only rarely been explored. New and improved delivery systems should provide prolonged drug action (i.e., ocular injection 1-2x per year) and effective dosing of otherwise inactive drugs. We are investigating ocular ADME and drug delivery issues in our research program.
Nanocarriers for Drug Delivery — Nanocarriers are widely investigated as potential solution for delivering drugs and genes into target sites. Important issues in this research include physical-chemical assembly of the nanocarriers, their surface interactions with biological media, cellular interactions, and controlled content release from the carriers. These issues must be understood, otherwise, the delivery process may be unreliable and only poorly effective. In our research program, we investigate DNA delivery by using nanoparticles – a complex and poorly effective process that is not well understood. We also carry out research on liposomes in relation to drug targeting and to light-triggered drug release.
Complex Organotypic Cell Models — Recent developments in biology (including stem cell biology, cell cloning, and induced pluripotent stem cells), and materials science (including responsive materials and nanofibers) have set the stage for improved 3D and other organotypic cell models that more accurately mimic human tissues. Biomaterial-based cell culture technologies are highly valuable as in vitro drug development tools and as potential cell therapies. We are currently investigating blood-retina barrier cell models, 3D cultures of hepatocytes and epidermis, and cell therapy approaches (e.g., cell microencapsulation).
