Zhejiang University: Dissolvable microneedle patch for treatment of inflammatory skin disorders

The research team led by Prof. PING Yuan from the Zhejiang University College of Pharmaceutical Sciences published their study in the journal Science Advances. They developed a dissolvable microneedle (MN) patch that can mediate transdermal co-delivery of CRISPR-Cas9–based genome-editing agents and glucocorticoids for the effective treatment of inflammatory skin disorders (ISDs).

ISDs represent one of the most persistent diseases that are generally characterized by the activation of the innate and adaptive immune responses through the production of proinflammatory cytokines. Pyrin domain-containing 3 (NLRP3), as one of the subtypes of inflammasomes, is reported to be associated with a variety of inflammatory and autoimmune skin conditions, including psoriasis and AD. Given the critical role of NLRP3 inflammasome in the pathogenesis of ISDs, efforts have been channeled into targeting NLRP3 inflammasomes to alleviate inflammatory responses. To this end, small molecular inhibitors have been actively investigated for their potential to target NLRP3 inflammasomes to treat ISDs in recent years. However, NLRP3 inflammasomes are primarily located at the epidermal and dermal layers of the human skin. For effective delivery, it is essential to consider the skin barriers that prevent the entry of the inhibitors at different levels. Thus, the efficient transdermal delivery of a highly specific, powerful, and direct NLRP3 inhibitor seems to be an ideal promising strategy to combat ISDs.

Schematic illustration of stepwise transdermal and intracellular delivery of genome-editing agents (Cas9) and glucocorticoids (Dex) for the treatment of ISDs.

The MN patch is developed for the transdermal co-delivery of the RNA-guided clustered regularly interspaced short palindromic repeat-associated nuclease protein 9 (CRISPR-Cas9)-based genome-editing agents and glucocorticoids for the effective treatment of ISDs. The MN patch is designed as follows: (i) polymer/Cas9 ribonucleoprotein (RNP) nanocomplexes for the intracellular delivery of Cas9 targeting NLRP3 inflammasome, (ii) dexamethasone (Dex)-loaded polymeric nanoparticles for the improved glucocorticoid therapy, and (iii) a dissolvable MN patch embedded with both Cas9 nanocomplexes and Dex nanoparticles for the transdermal co-delivery of two nanoformulations. Once inserted into the skin, the MN is dissolved quickly to release two types of nanoformulations. The intracellular delivery of Cas9 RNP, enabled by the polymeric carrier, ensures the efficient genome editing of NLRP3 gene within subcutaneous keratinocytes and immune cells. In the meantime, the disruption of NLRP3 inflammasomes can further improve the sensitivity of glucocorticoid therapy. As Dex is well documented for its ability to induce the dilation of nuclear pores during its translocation process, the intracellular delivery of Dex will simultaneously contribute to the nuclear entry of genome-editing agents. Furthermore, by using hyaluronic acid (HA) and collagen tripeptide (CTP) as the matrix materials, the MN patch is marked by its good biocompatibility and its capability of promoting collagen synthesis, reducing transepidermal water loss (TEWL), and facilitating the tissue repair of skin lesions.

Mitigation of DNCB-induced AD via dual MN patch.

As shown in this study, MN-assisted genome editing can tremendously improve glucocorticoid therapy—a kind of therapy superior to the treatment by clinically available Dex cream or tacrolimus ointment. “This work offers innovative insights into the rational design of transdermal delivery systems and defines an effective therapeutic option for the treatment of ISDs,” said PING Yuan.

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