Dissolving microneedles are a subgroup of microneedle types that completely dissolve within the skin. During this dissolving process the vaccine, stored in the needle matrix, is released into the... Show moreDissolving microneedles are a subgroup of microneedle types that completely dissolve within the skin. During this dissolving process the vaccine, stored in the needle matrix, is released into the skin. Dissolving microneedles are made of a water-soluble, inert and safe material, such as hyaluronic acid. The microneedles have been used to vaccinate via the skin, which is a very immune competent organ that holds great potential for vaccine delivery. The minimally invasive and easy nature of the injections can reduce the risk of infections and alleviate the need for trained personnel. Furthermore, they eliminate all sharp waste as the needles dissolve during drug delivery.The goals of this project has been to improve the immunogenicity of vaccines through skin delivery, allowing for increased understanding of skin immunology and the development of pain free and safe vaccine delivery systems. Show less
Leone, M.; Romeijn, S.; Slütter, B.; O'Mahony, C.; Kersten, G.; Bouwstra, J.A. 2020
Biomaterials used as matrix for dissolving micro needles (dMNs) may affect the manufacturing process as well as the potency of the active pharmaceutical ingredient, e.g. the immunogenicity of... Show moreBiomaterials used as matrix for dissolving micro needles (dMNs) may affect the manufacturing process as well as the potency of the active pharmaceutical ingredient, e.g. the immunogenicity of incorporated vaccine antigens. The aim of this study was to investigate the effect of the molecular weight of hyaluronan, a polymer widely used in the fabrication of dMNs, ranging in molecular weight from 4.8 kDa to 1.8 MDa, on the dissolution of microneedles in the skin in time as well as the antibody response in mice and T-cell activation in vitro. Hyaluronan molecular weight (HA-MWs) did not affect antibody responses (when lower than 150 kDa) nor CD4 + T-cell responses against model antigen ovalbumin. However, the HA-MWs had an effect on the fabrication of dMNs. The 1.8 MDa HA was not suitable for the fabrication of dMNs. Similarly, the 4.8 kDa HA generated dMN arrays less robust compared to the other HA-MWs requiring optimization of the drying conditions. Finally, higher HAMWs led to longer application time of dMN arrays for a complete dissolution of microneedles into the skin. Specifically, we identified 20 kDa HA as the optimal HA-MW for the fabrication of dMNs as with this MW the dMNs are robust and dissolve fast in the skin without affecting immunogenicity. Show less
Leone, M.; Priester, M.I.; Romeijn, S.; Nejadnik, M.R.; Mönkäre, J.; O'Mahony, C.; ... ; Bouwstra, J.A. 2019
The purpose of this study was to optimize the manufacturing of dissolving microneedles (dMNs) and to increase the antigen loading in dMNs to investigate the effect on their physicochemical... Show moreThe purpose of this study was to optimize the manufacturing of dissolving microneedles (dMNs) and to increase the antigen loading in dMNs to investigate the effect on their physicochemical properties. To achieve this, a novel single-array wells polydimethylsiloxane mold was designed, minimizing antigen wastage during fabrication and achieving homogeneous antigen distribution among the dMN arrays. Using this mold, hyaluronan (HA)-based dMNs were fabricated and tested for maximal ovalbumin (OVA) content. dMNs could be fabricated with an OVA:HA ratio as high as 1:1 (w/w), without compromising their properties such as shape and penetration into the ex vivo human skin, even after storage at high humidity and temperature. High antigen loading did not induce protein aggregation during dMN fabrication as demonstrated by complementary analytical methods. However, the dissolution rate in ex vivo human skin decreased with increasing antigen loading. About 2.7 µg OVA could be delivered in mice by using a single array with an OVA:HA ratio of 1:3 (w/w). Intradermal vaccination with dMNs induced an immune response similar as subcutaneous injection and faster than after hollow microneedle injection. In conclusion, results suggest that (i) the polydimethylsiloxane mold design has an impact on the manufacturing of dMNs, (ii) the increase in antigen loading in dMNs affects the microneedle dissolution and (iii) dMNs are a valid alternative for vaccine administration over conventional injection. Show less
Mönkare, J.; Pontier, M.J.; Kampen, E.E.M. van; Du, G.; Leone, M.; Romeijn, S.G.; ... ; Bouwstra, J.A. 2018
Skin is an attractive but also very challenging immunisation site for particulate subunit vaccines. The aim of this study was to develop hyaluronan (HA)-based dissolving microneedles (MNs) loaded... Show moreSkin is an attractive but also very challenging immunisation site for particulate subunit vaccines. The aim of this study was to develop hyaluronan (HA)-based dissolving microneedles (MNs) loaded with PLGA nanoparticles (NPs) co-encapsulating ovalbumin (OVA) and poly(I:C) for intradermal immunisation. The NP:HA ratio used for the preparation of dissolving MNs appeared to be critical for the quality of MNs and their dissolution in ex vivo human skin. Asymmetrical flow field-flow fractionation and dynamic light scattering were used to analyse the NPs released from the MNs in vitro. Successful release of the NPs depended on the drying conditions during MN preparation. The delivered antigen dose from dissolving MNs in mice was determined to be 1 µg OVA, in NPs or as free antigen, by using near-infrared fluorescence imaging. Finally, the immunogenicity of the NPs after administration of dissolving MNs (NP:HA weight ratio 1:4) was compared with that of hollow MN-delivered NPs in mice. Immunization with free antigen in dissolving MNs resulted in equally strong immune responses compared to delivery by hollow MNs. However, humoral and cellular immune responses evoked by NP-loaded dissolving MNs were inferior to those elicited by NPs delivered through a hollow MN. In conclusion, we identified several critical formulation parameters for the further development of NP-loaded dissolving MNs. Show less
