Transdermal delivery of human growth hormone via laser-generated micropores

Development of nano-liposomal human growth hormone as a topical formulation for preventing uvb-induced skin damage

Due to its involvement in skin maintenance and repair, topical administration of recombinant human growth hormone (rhGH) is an interesting strategy for therapeutic purposes. We have formulated and characterized a topical rhGH-loaded liposomal formulation (rhGH-Lip) and evaluated its safety, biological activity, and preventive role against UVB-induced skin damage. The rhGH-Lip had an average size and zeta potential of 63 nm and -33 mV, respectively, with 70 % encapsulation efficiency. The formulation was stable at 4 °C for at least one year. The SDS-PAGE and circular dichroism results showed no structural alterations in rhGH upon encapsulation. In vitro, studies in HaCaT, HFFF-2, and Ba/F3-rhGHR cell lines confirmed the safety and biological activity of rhGH-Lip. Franz diffusion cell study showed increased rhGH skin permeation compared to free rhGH. Animal studies in nude mice showed that liposomal rhGH prevented UVB-induced epidermal hyperplasia, angiogenesis, wrinkle formation, and collagen loss, as well as improving skin moisture. The results of this study show that rhGH-Lip is a stable, safe, and effective skin delivery system and has potential as an anti-wrinkle formulation for topical application. This study also provides a new method for the topical delivery of proteins and merits further investigation.

Impact of Formulation and Microneedle Length on Transdermal Metronidazole Permeation through Microneedle-Treated Skin

OBJECTIVE

This study aimed to determine the impact of formulation (gel vs cream) and microneedle characteristics (length, number) on permeation of metronidazole through excised microneedle-treated skin. The long-term goal is to apply these results towards a pharmacokinetic study in human subjects with diverse skin types, using in vitro flux data to determine dosing conditions and ultimately establish in vitro-in vivo correlations.

METHODS

Metronidazole release from 0.75% gel and cream was quantified with flow-through diffusion cells, using a cellulose membrane. Excised porcine skin was treated with stainless steel microneedles (500 or 800 μm length), to create 50 or 100 micropores. Metronidazole gel or cream was applied to microneedle-treated skin and replaced every 48 h for up to 7 days. Metronidazole permeation was quantified using HPLC. Intact skin (no microneedle treatment) served as controls.

RESULTS

Metronidazole release was faster from the gel vs cream. At 7 days there was no difference between gel vs cream in total metronidazole permeated through intact skin. For both formulations, metronidazole permeation was significantly higher (vs intact skin) following microneedle application, regardless of microneedle length or micropore number. Increasing microneedle length and micropore number enhanced MTZ permeation multiple fold for both gel and cream. The greatest enhancement in total permeation for both formulations was achieved with the 800 μm MN, 100 micropore condition.

CONCLUSIONS

Formulation and microneedle conditions both impacted metronidazole permeation. These data will be used to estimate in vivo serum concentrations after applying metronidazole to microneedle-treated skin in humans.

Exploiting Unique Features of Microneedles to Modulate Immunity

Microneedle arrays (MNAs) are small patches containing hundreds of short projections that deliver signals directly to dermal layers without causing pain. These technologies are of special interest for immunotherapy and vaccine delivery because they directly target immune cells concentrated in the skin. The targeting abilities of MNAs result in efficient immune responses-often more protective or therapeutic-compared to conventional needle delivery. MNAs also offer logistical benefits, such as self-administration and transportation without refrigeration. Thus, numerous preclinical and clinical studies are exploring these technologies. Here the unique advantages of MNA, as well as critical challenges-such as manufacturing and sterility issues-the field faces to enable widespread deployment are discussed. How MNA design parameters can be exploited for controlled release of vaccines and immunotherapies, and the application to preclinical models of infection, cancer, autoimmunity, and allergies are explained. Specific strategies are also discussed to reduce off-target effects compared to conventional vaccine delivery routes, and novel chemical and manufacturing controls that enable cargo stability in MNAs across flexible intervals and temperatures. Clinical research using MNAs is then examined. Drawbacks of MNAs and the implications, and emerging opportunities to exploit MNAs for immune engineering and clinical use are concluded.

Laser microporation facilitates topical drug delivery: a comprehensive review about preclinical development and clinical application

INTRODUCTION

Topical drug delivery is highly attractive and yet faces tissue barrier challenges. Different physical and chemical methods have been explored to facilitate topical drug delivery.

AREAS COVERED

Ablative fractional laser (AFL) has been widely explored by the scientific community and dermatologists to facilitate topical drug delivery since its advent less than two decades ago. This review introduces the major efforts in exploration of AFL to facilitate transdermal, transungual, and transocular drug delivery in preclinical and clinical settings.

EXPERT OPINION

Most of the preclinical and clinical studies find AFL to be safe and highly effective to facilitate topical drug delivery with little restriction on physicochemical properties of drugs. Clinical studies support AFL to enhance drug efficacy, shorten treatment time, reduce pain, improve cosmetic outcomes, reduce systemic drug exposure, and improve safety. Considering most of the clinical trials so far involved a small sample size and were in early phase, future trials will benefit from enrolling a large group of patients for thorough evaluation of the safety and efficacy of AFL-assisted topical drug delivery. The manufacturing of small and less costly AFL devices will also facilitate the translation of AFL-assisted topical drug delivery.

Sustained transdermal delivery of human growth hormone from niosomal gel: in vitro and in vivo studies

Human growth hormone (hGH) is widely used to treat several diseases for decades. However, the current treatment regime requires frequent injections via subcutaneous route due to short in vivo half-life, which leads to pain and poor patient compliance. In this study, a novel transdermal (non-invasive) hGH loaded niosomes gel was prepared to reduce the frequency of subcutaneous injections and to improve the patient compliance. Niosomes were prepared by film hydration technique at three levels of cholesterol. The particle size and entrapment efficiency increases with an increase in the level of cholesterol. Transmission electron microscopy images confirmed the spherical shape of niosomes without aggregation. Texture profiles analysis indicates that the niosomal gel has the required mechanical properties for transdermal application. The ex vivo permeation profile showed sustain hGH release for 4 days from the niosomal gel compared to 24 h from the control gel without niosomes. A rabbit skin irritation study showed no sign of irritation after application of niosomal gel. The pharmacokinetic parameters in the rat model showed 7.22-fold higher bioavailability with niosomal gel compared to control gel. In conclusion, the study demonstrated the potential of niosomal gel as an effective long-term sustained release strategy for hGH delivery to replace traditional subcutaneous injections.

Transdermal Delivery of Baclofen Using Iontophoresis and Microneedles

Baclofen, a GABA_b agonist, is used in the treatment of multiple sclerosis, a neurodegenerative disease. Currently available dosage forms to deliver baclofen are through the oral and the intrathecal routes. The disadvantage of oral baclofen is that it requires administering the drug multiple times a day, owing to baclofen's short half-life. On the other hand, intrathecal baclofen pumps are invasive and cannot be an alternative to oral baclofen. Hence, there is a need to develop a dosage form that can deliver baclofen non-invasively and for an extended period at a steady rate, increasing the dosing interval. A transdermal baclofen delivery system might be the solution to this problem. Hence, this research focuses on evaluating microneedles, iontophoresis, and a combination of microneedles-iontophoresis as transdermal delivery enhancement strategies for baclofen. In vitro permeation studies were conducted on dermatomed porcine ear skin using vertical Franz diffusion cells to evaluate transdermal baclofen delivery. Anodal iontophoresis was applied at a current density of 0.5 mA/cm², and transdermal delivery was assessed from pH 4.5 (45.51±0.76 μg/cm²) and pH 7.4 (68.84±10.13 μg/cm²) baclofen solutions. Iontophoresis enhanced baclofen delivery but failed to reach target delivery. Maltose microneedles were used to create hydrophilic microchannels on the skin, and this technique enhanced baclofen delivery by 89-fold. Both microneedles (447.88±68.06 μg/cm²) and combination of microneedles - iontophoresis (428.56±84.33 μg/cm²) reached the target delivery range (222-1184 μg/cm²) for baclofen. The findings of this research suggest that skin could be a viable route for delivery of baclofen. Graphical Abstract.

Effect of mRNA Delivery Modality and Formulation on Cutaneous mRNA Distribution and Downstream eGFP Expression

In vitro transcribed messenger ribonucleic acid (mRNA) constitutes an emerging therapeutic class with several clinical applications. This study presents a systematic comparison of different technologies—intradermal injection, microneedle injection, jet injection, and fractional laser ablation—for the topical cutaneous delivery of mRNA. Delivery of Cy5 labeled mRNA and non-labeled enhanced green fluorescent protein (eGFP) expressing mRNA was investigated in a viable ex vivo porcine skin model and monitored for 48 h. Forty 10 µm-thick horizontal sections were prepared from each skin sample and Cy5 labeled mRNA or eGFP expression visualized as a function of depth by confocal laser scanning microscopy and immunohistochemistry. A pixel-based method was used to create a semi-quantitative biodistribution profile. Different spatial distributions of Cy5 labeled mRNA and eGFP expression were observed, depending on the delivery modality; localization of eGFP expression pointed to the cells responsible. Delivery efficiencies and knowledge of delivery sites can facilitate development of efficient, targeted mRNA-based therapeutics.

Moderate Heat-Assisted Gene Electrotransfer as a Potential Delivery Approach for Protein Replacement Therapy through the Skin

Gene-based approaches for protein replacement therapies have the potential to reduce the number of administrations. Our previous work demonstrated that expression could be enhanced and/or the applied voltage reduced by preheating the tissue prior to pulse administration. In the current study, we utilized our 16-pin multi-electrode array (MEA) and incorporated nine optical fibers, connected to an infrared laser, between each set of four electrodes to heat the tissue to 43 °C. For proof of principle, a guinea pig model was used to test delivery of reporter genes. We observed that when the skin was preheated, it was possible to achieve the same expression levels as gene electrotransfer without preheating, but with a 23% reduction of applied voltage or a 50% reduction of pulse number. With respect to expression distribution, preheating allowed for delivery to the deep dermis and muscle. This suggested that this cutaneous delivery approach has the potential to achieve expression in the systemic circulation, thus this protocol was repeated using a plasmid encoding Human Factor IX. Elevated Factor IX serum protein levels were detected by ELISA up to 100 days post gene delivery. Further work will involve optimizing protein levels and scalability in an effort to reduce application frequency.

Enhancing Permeation of Drug Molecules Across the Skin via Delivery in Nanocarriers: Novel Strategies for Effective Transdermal Applications

The transdermal route of administration provides numerous advantages over conventional routes i.e., oral or injectable for the treatment of different diseases and cosmetics applications. The skin also works as a reservoir, thus deliver the penetrated drug for more extended periods in a sustained manner. It reduces toxicity and local irritation due to multiple sites for absorption and owes the option of avoiding systemic side effects. However, the transdermal route of delivery for many drugs is limited since very few drugs can be delivered at a viable rate using this route. The stratum corneum of skin works as an effective barrier, limiting most drugs' penetration posing difficulty to cross through the skin. Fortunately, some non-invasive methods can significantly enhance the penetration of drugs through this barrier. The use of nanocarriers for increasing the range of available drugs for the transdermal delivery has emerged as a valuable and exciting alternative. Both the lipophilic and hydrophilic drugs can be delivered via a range of nanocarriers through the stratum corneum with the possibility of having local or systemic effects to treat various diseases. In this review, the skin structure and major obstacle for transdermal drug delivery, different nanocarriers used for transdermal delivery, i.e., nanoparticles, ethosomes, dendrimers, liposomes, etc., have been discussed. Some recent examples of the combination of nanocarrier and physical methods, including iontophoresis, ultrasound, laser, and microneedles, have also been discussed for improving the therapeutic efficacy of transdermal drugs. Limitations and future perspectives of nanocarriers for transdermal drug delivery have been summarized at the end of this manuscript.

Development and evaluation of a heparin gel for transdermal delivery via laser-generated micropores

Aim: Our study investigated the feasibility of transdermal delivery of heparin, an anticoagulant used against venous thromboembolism, as an alternative to intravenous administration. Materials & methods: Skin was pretreated using ablative laser (Precise Laser Epidermal System [P.L.E.A.S.E.^®] technology) for enhanced delivery of heparin. In vitro permeation studies using static Franz diffusion cells provided a comparison between delivery from 0.3% w/v heparin-loaded poloxamer gel and solution across untreated and laser-treated dermatomed porcine ear skin. Results: No passive delivery of heparin was observed. Laser-assisted delivery from solution (26.07 ± 1.82 μg/cm²) was higher (p < 0.05) than delivery from heparin gel (11.28 ± 5.32 μg/cm²). However, gel is likely to sustain the delivery over prolonged periods like a maintenance dose via continuous intravenous infusion. Conclusion: Thus, ablative laser pretreatment successfully delivered heparin, establishing the feasibility of delivering hydrophilic macromolecules using the transdermal route.

Fundamentals of fractional laser-assisted drug delivery: An in-depth guide to experimental methodology and data interpretation

In the decade since their advent, ablative fractional lasers have emerged as powerful tools to enhance drug delivery to and through the skin. Effective and highly customizable, laser-assisted drug delivery (LADD) has led to improved therapeutic outcomes for several medical indications. However, for LADD to reach maturity as a standard treatment technique, a greater appreciation of its underlying science is needed. This work aims to provide an in-depth guide to the technology's fundamental principles, experimental methodology and unique aspects of LADD data interpretation. We show that drug's physicochemical properties including solubility, molecular weight and tissue binding behavior, are crucial determinants of how laser channel morphology influences topical delivery. Furthermore, we identify strengths and limitations of experimental models and drug detection techniques, interrogating the usefulness of in vitro data in predicting LADD in vivo. By compiling insights from over 75 studies, we ultimately devise an approach for intelligent application of LADD, supporting its implementation in the clinical setting.

Impact of the Transfersome Delivered Human Growth Hormone on the Dermal Fibroblast Cells

Objective:

Transfersomes are highly flexible vesicles that are capable of passing through pores smaller than their own sizes due to their elastochemical characteristics, and thus play a key role in drug delivery to the skin.

Methods:

In this study, we used transdermal delivery of growth hormone-encapsulated transferosomes (F1 and F2) as antiaging strategy, with the resulting effects being subsequently evaluated. The size, distribution and zeta potential of the particles, together with the in vitro skin permeation and biological activity of the growth hormone loaded onto the transfersomes were measured.

Results:

The data demonstrated that treatment of fibroblasts with encapsulated hGH increased cell migration, proliferation and collagen I and III gene expression. According to our results, the maximum amount of growth hormone that passes through the skin during a 24 h time period was 489.54 and 248.46 ng/cm3, for the F1 and F2 transfersomes, respectively. In addition, it was determined that F1 formula as the more efficient carrier, showed no toxicity against cells. With regard to fibroblasts, as one of the most important cells involved in collagen synthesis, skin aging and wound healing, concentrations of growth hormone encapsulated in transferosomes that had an effect on fibroblast growth and division, were determined. The results demonstrated that effective concentrations of the encapsulated growth hormone increased the expression of collagen I and collagen III genes.

Conclusion:

Furthermore, analyzing the rate of fibroblast cell migration showed that migration increased significantly at 700 ng/ml growth hormone concentrations, as compared to that of the control.

Rapidly Fabricated Microneedle Arrays Using Magnetorheological Drawing Lithography for Transdermal Drug Delivery

Microneedle arrays (MAs) are among the most promising transdermal drug delivery systems in the last decades due to its minimally invasive nature, convenient operation, and first-pass-metabolism avoidance. However, most MA fabrication methods are difficult to operate, need multiple steps, or require expensive equipment. A novel magnetorheological drawing lithography approach was proposed to rapidly fabricate a flexible microneedle array (FMA) for transdermal drug delivery. A 3D structural liquid MA was drawn in one step from the droplets of curable magnetorheological fluid and maintained its shape under an external magnetic field. The liquid MA was subsequently solidified and sputter-coated with the Ti/Au film to fabricate FMA. FMA morphology, mechanical properties, and transdermal drug delivery performance in vitro were experimentally investigated. FMA consisted of a 5 × 5 cone-shaped microneedle array on a PET flexible substrate. FMA exhibited good strength and excellent penetration performance. It could easily penetrate into skin without breakage, creating microchannels for the promotion of skin permeability. Drugs could be well permeated and diffused in the skin along the microchannels created by FMA. Finally, a dissolvable microneedle array (DMA) was also fabricated by a micromolding technique using FMA as a master template. The DMA exhibited good dissolvable and permeable performance in the agarose block.

Fractional laser ablation for the targeted cutaneous delivery of an anti-CD29 monoclonal antibody - OS2966

Monoclonal antibodies targeting cytokines are administered parenterally for the systemic treatment of severe psoriasis. However, systemic exposure to the biologic increases the risk of side-effects including immunosuppression, whereas only a small fraction of the active molecules actually reaches the target organ, the skin. This preclinical study examines the feasibility of delivering a humanized anti-CD29 monoclonal antibody (OS2966) topically to skin using minimally-invasive fractional laser ablation. This approach would enable the targeted use of a biologic for the treatment of recalcitrant psoriatic plaques in patients with less widespread disease while minimizing the risk of systemic exposure. First, the effect of a wide range of laser poration conditions on skin permeation and deposition of OS2966 was tested in vitro to determine optimal microporation parameters. Subsequently, confocal laser scanning microscopy was employed to visualize the distribution of fluorescently-labelled OS2966 in skin. The results demonstrated that delivery of OS2966 into and across skin was feasible. Above fluences of 35.1 J/cm², skin deposition and permeation were statistically superior to passive delivery reaching values up to 3.7 ± 1.2 µg/cm² at the most aggressive condition. Selective targeting of the skin was also possible since ≥70% of the OS2966 was delivered locally to the skin. Although nanogramme quantities were able to permeate across skin, these amounts were orders of magnitude lower than levels seen following subcutaneous or intravenous injection and would result in minimal systemic exposure in vivo. The diffusion of fluorescently-labelled OS2966 into the skin surrounding the pores was clearly higher than in intact skin and demonstrated the feasibility of delivering the antibody at least as deep as the dermo-epithelial junction, a critical border region where inflammatory cells cross to promote disease progression. These preliminary results confirm that fractional laser ablation can be used for the cutaneous delivery of OS2966 and now preclinical/clinical studies are required to demonstrate therapeutic efficacy.

mPEG-PLA and PLA-PEG-PLA nanoparticles as new carriers for delivery of recombinant human Growth Hormone (rhGH)

mPEG-PLA and PLA-PEG-PLA copolymeric nanoparticles with three different PLA to PEG ratios are synthesized and used for encapsulation of recombinant human Growth hormone (rhGH). The structure and composition of the synthesized copolymers were analyzed by ¹H NMR and GPC techniques. Moreover, morphology, encapsulation efficiency (EE), cytotoxicity, release profile and stability of the encapsulated rhGH were measured. Structural analysis of the prepared copolymers showed that they were successfully synthesized with approximately expected molecular weight and relatively low size distribution. It was also revealed that by increasing amounts of PLA/PEG ratio, EE content and size of nanoparticles were increased. Release profile evaluation of rhGH from both formulations indicated that copolymeric nanoparticles of Di-B2 and Tri-B2 exhibited the best results among the synthesized nanospheres, by having initial burst release of 17.5% and 28% and then slow and constant release of rhGH up to 65% and 77% of the encapsulated drug, respectively. Furthermore, results of HPLC, SDS-PAGE and CD analyses showed stability of rhGH during encapsulation and release from nanoparticles. Finally, the results showed that these two formulations provided safe and efficient sustained release of rhGH for more than a month and they have the potential to do further studies under in vivo conditions.