Enhanced Transdermal Delivery of rhHAPLN1 by Soluball® Promotes Pericellular Matrix Stability and Keratinocyte Protection

Background/Objectives: The pericellular matrix (PCM), a highly hydrated hyaluronan (HA)-rich extracellular structure surrounding keratinocytes, serves as a critical regulator of cellular protection, mechanobiological signaling, and epidermal microenvironmental homeostasis. Increasing evidence suggests that age- and stress-associated degradation of the HA-rich PCM contributes to impaired regenerative capacity and increased cellular vulnerability. Recombinant human hyaluronan and proteoglycan link protein 1 (rhHAPLN1) has emerged as a promising PCM-stabilizing biomolecule; however, its therapeutic application remains limited by poor skin permeability resulting from the barrier properties of the stratum corneum and the molecular size constraints governing hydrophilic macromolecule delivery. Methods: In the present study, we developed Soluball®, a dodecylamine-templated mesoporous silica-based carrier system designed to enhance the transdermal delivery of rhHAPLN1. Results: In vitro analyses demonstrated that rhHAPLN1 effectively preserved both the structural integrity and functional hydrodynamic volume of the PCM against hyaluronidase (HAdase)-induced degradation in HaCaT keratinocytes. Furthermore, rhHAPLN1 exhibited no significant cytotoxicity at concentrations up to 1 μg/mL and significantly enhanced keratinocyte proliferation under serum-free conditions. Physicochemical characterization revealed that Soluball® possessed a relatively uniform particle size distribution (284.6 nm), a high specific surface area (1048 m2/g), and a mesoporous architecture with an average pore diameter of 3.8 nm, supporting efficient loading of hydrophilic biomolecules. Ex vivo permeation studies using human cadaver skin demonstrated that Soluball®-encapsulated rhHAPLN1 (H-S powder) significantly enhanced cumulative transdermal permeation compared with free rhHAPLN1 (5.54% vs. 0.88%, respectively). To further evaluate platform versatility, water-soluble Vitamin C was employed as a secondary model cargo. Vita-Soluball® exhibited markedly enhanced permeation across both Strat-M® artificial membranes and pig epidermis, achieving cumulative permeation values of 119.12 ± 9.38 μg/mL and 150.39 ± 29.20 μg/mL, respectively. Conclusions: Collectively, these findings suggest that rhHAPLN1 functions as an effective stabilizer of the HA-rich PCM and that Soluball® enhances the transdermal delivery of hydrophilic biomolecules. Overall, Soluball® may represent a promising transdermal delivery platform for hydrophilic biomolecules, although further in vivo validation is warranted.