Juha Mönkäre

Bio: Juha Mönkäre is an academic researcher from Leiden University. The author has contributed to research in topics: Drug delivery & PLGA. The author has an hindex of 13, co-authored 21 publications receiving 712 citations. Previous affiliations of Juha Mönkäre include University of Eastern Finland.

Dissolving microneedle patches for dermal vaccination

Abstract: The dermal route is an attractive route for vaccine delivery due to the easy skin accessibility and a dense network of immune cells in the skin. The development of microneedles is crucial to take advantage of the skin immunization and simultaneously to overcome problems related to vaccination by conventional needles (e.g. pain, needle-stick injuries or needle re-use). This review focuses on dissolving microneedles that after penetration into the skin dissolve releasing the encapsulated antigen. The microneedle patch fabrication techniques and their challenges are discussed as well as the microneedle characterization methods and antigen stability aspects. The immunogenicity of antigens formulated in dissolving microneedles are addressed. Finally, the early clinical development is discussed.

Mesoporous Silicon (PSi) for Sustained Peptide Delivery: Effect of PSi Microparticle Surface Chemistry on Peptide YY3-36 Release

Abstract: To achieve sustained peptide delivery via mesoporous silicon (PSi) microparticles and to evaluate the effects of different surface chemistries on peptide YY3-36 (PYY3-36) delivery. PYY3-36 was loaded into thermally oxidized (TOPSi), thermally hydrocarbonized (THCPSi) and undecylenic acid treated THCPSi (UnTHCPSi) microparticles with comparable porous properties. In vitro, PYY3-36 release was investigated by centrifuge. In vivo, PYY3-36 plasma concentrations were analyzed after delivery in microparticles or solution. Achieved loading degrees were high (12.2 – 16.0% w/w). PYY3-36 release was sustained from all microparticles; order of PYY3-36 release was TOPSi > THCPSi > UnTHCPSi both in vitro and in vivo. In mice, PSi microparticles achieved sustained PYY3-36 release over 4 days, whereas PYY3-36 solution was eliminated in 12 h. In vitro, only 27.7, 14.5 and 6.2% of loaded PYY3-36 was released from TOPSi, THCPSi and UnTHCPSi, respectively. Absolute PYY3-36 bioavailabilities were 98, 13, 9 and 38% when delivered subcutaneously in TOPSi, THCPSi, UnTHCPSi and solution, respectively. The results clearly demonstrate improved bioavailability of PYY3-36 via TOPSi and the importance of surface chemistry of PSi on peptide release. PSi represents a promising sustained and tailorable release system for PYY3-36.

Novel Delivery Systems for Improving the Clinical Use of Peptides

Abstract: Peptides have long been recognized as a promising group of therapeutic substances to treat various diseases. Delivery systems for peptides have been under development since the discovery of insulin for the treatment of diabetes. The challenge of using peptides as drugs arises from their poor bioavailability resulting from the low permeability of biological membranes and their instability. Currently, subcutaneous injection is clinically the most common administration route for peptides. This route is cost-effective and suitable for self-administration, and the development of appropriate dosing equipment has made performing the repeated injections relatively easy; however, only few clinical subcutaneous peptide delivery systems provide sustained peptide release. As a result, frequent injections are needed, which may cause discomfort and additional risks resulting from a poor administration technique. Controlled peptide delivery systems, able to provide required therapeutic plasma concentrations over an extended period, are needed to increase peptide safety and patient compliancy. In this review, we summarize the current peptidergic drugs, future developments, and parenteral peptide delivery systems. Special emphasis is given to porous silicon, a novel material in peptide delivery. Biodegradable and biocompatible porous silicon possesses some unique properties, such as the ability to carry exceptional high peptide payloads and to modify peptide release extensively. We have successfully developed porous silicon as a carrier material for improved parenteral peptide delivery. Nanotechnology, with its different delivery systems, will enable better use of peptides in several therapeutic applications in the near future.

BRIEF COMMUNICATION ARISING: Gut hormone PYY3-36 physiologically inhibits food intake

Abstract: Food intake is regulated by the hypothalamus, including the melanocortin and neuropeptide Y (NPY) systems in the arcuate nucleus. The NPY Y2 receptor (Y2R), a putative inhibitory presynaptic receptor, is highly expressed on NPY neurons in the arcuate nucleus, which is accessible to peripheral hormones. Peptide YY3-36 (PYY3-36), a Y2R agonist, is released from the gastrointestinal tract postprandially in proportion to the calorie content of a meal. Here we show that peripheral injection of PYY3-36 in rats inhibits food intake and reduces weight gain. PYY3-36 also inhibits food intake in mice but not in Y2r-null mice, which suggests that the anorectic effect requires the Y2R. Peripheral administration of PYY3-36 increases c-Fos immunoreactivity in the arcuate nucleus and decreases hypothalamic Npy messenger RNA. Intra-arcuate injection of PYY3-36 inhibits food intake. PYY3-36 also inhibits electrical activity of NPY nerve terminals, thus activating adjacent pro-opiomelanocortin (POMC) neurons. In humans, infusion of normal postprandial concentrations of PYY3-36 significantly decreases appetite and reduces food intake by 33% over 24 h. Thus, postprandial elevation of PYY3-36 may act through the arcuate nucleus Y2R to inhibit feeding in a gut–hypothalamic pathway.

Biodegradable 3D printed polymer microneedles for transdermal drug delivery.

Abstract: Biodegradable polymer microneedle (MN) arrays are an emerging class of transdermal drug delivery devices that promise a painless and sanitary alternative to syringes; however, prototyping bespoke needle architectures is expensive and requires production of new master templates. Here, we present a new microfabrication technique for MNs using fused deposition modeling (FDM) 3D printing using polylactic acid, an FDA approved, renewable, biodegradable, thermoplastic material. We show how this natural degradability can be exploited to overcome a key challenge of FDM 3D printing, in particular the low resolution of these printers. We improved the feature size of the printed parts significantly by developing a post fabrication chemical etching protocol, which allowed us to access tip sizes as small as 1 μm. With 3D modeling software, various MN shapes were designed and printed rapidly with custom needle density, length, and shape. Scanning electron microscopy confirmed that our method resulted in needle tip sizes in the range of 1-55 μm, which could successfully penetrate and break off into porcine skin. We have also shown that these MNs have comparable mechanical strengths to currently fabricated MNs and we further demonstrated how the swellability of PLA can be exploited to load small molecule drugs and how its degradability in skin can release those small molecules over time.