Study summary · research use only
Development of a Sensory Neuron-Integrated Skin Spheroid Model for the Evaluation of Neuropeptide-Based Topical Delivery Systems
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
In this study combining a sensory neuron-integrated skin spheroid (SS) model and ex vivo human skin, the authors developed a platform incorporating keratinocytes, fibroblasts, adipocytes, and sensory neurons to evaluate topical neuropeptide delivery. The model's responsiveness was tested using acetyl hexapeptide-3 (HEX-3), a neuropeptide reported to inhibit acetylcholine release; HEX-3 was internalized by spheroid cells, accumulating preferentially around sensory neurons, and ex vivo human skin studies confirmed HEX-3 crossed the stratum corneum and accumulated in deeper layers. Treatment with the film was associated with increased skin hydration, reduced scaling, and improved stratum corneum organization after 48 h. HEX-3 was reported to suppress acetylcholine release, upregulate SOD2, and stimulate type I collagen synthesis, with increased collagen also seen in aged human skin samples and in the spheroid model.
Abstract
The skin is a complex organ composed of multiple layers and diverse cell types, including keratinocytes, fibroblasts, adipocytes, and sensory neurons, which maintain its structural and functional integrity together. Conventional in vitro and ex vivo models help investigate drug permeation and selected biological effects. However, they are limited in replicating neural interactions critical for assessing the efficacy of neuropeptide-based therapies. To address this limitation, a sensory neuron-integrated skin spheroid (SS) model was established, incorporating key skin cell types and providing a rapid, adaptable, and physiologically relevant platform for screening the biological activity of topical delivery systems targeting neuronal pathways. The model's responsiveness was demonstrated using acetyl hexapeptide-3 (HEX-3), a neuropeptide that inhibits acetylcholine release. HEX-3 was internalized by spheroid cells, with preferential accumulation around sensory neurons, confirming targeted cellular uptake. In parallel, ex vivo human skin studies confirmed that HEX-3 can traverse the stratum corneum and accumulate in deeper layers. Treatment with this film enhanced skin hydration, reduced scaling, and improved the structural organization of the stratum corneum after 48 h. Functional assays using the SS model showed that HEX-3 treatment suppressed acetylcholine release, upregulated the antioxidant enzyme SOD2, and stimulated type I collagen synthesis. In aged skin samples, the application of HEX-3 significantly increased collagen levels. This effect was mirrored in the spheroid model, which reached collagen levels comparable to those of aged human skin upon treatment. These findings establish the SS model as a robust platform for evaluating the biological activity of neuropeptide-based topical therapies, offering valuable insights for developing advanced strategies for skin rejuvenation and repair.
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