Co-delivery of triamcinolone acetonide and verapamil for synergistic treatment of hypertrophic scars via carboxymethyl chitosan and Bletilla striata polysaccharide-based microneedles

Hypertrophic scar (HS) is a frequently diagnosed skin disease that is difficult to treat. HS is usually associated with itching and pain and causes both physical and psychological issues. In this study, a safe, convenient, and efficient therapy for HS is developed. Carboxymethyl chitosan (CMCH) and Bletilla striata polysaccharide (BSP) are used to prepare microneedles (MN) via a micro-molding method. Hydroxypropyl β-cyclodextrin (HP-β-CD) is used to encapsulate triamcinolone acetonide (TA) and the obtained inclusion is co-loaded with verapamil (VRP) to MN. The MN is then attached to an Ethyl cellulose (EC) base layer to obtain a MN patch. The MN patch has uniform needles, sufficient mechanical strength, good penetration and dissolution in skin, and low cytotoxicity. It also significantly decreases the thickness of HS, and hydroxyproline (HYP) and transforming growth factor-beta 1 (TGF-β1) expression in HS, improves collagen fiber arrangement, and reduces dermis congestion and hyperplasia.