Innovative biomaterial-based microneedles for the treatment of pathological scars

Pathological scars arise when dermal fibroblasts experience prolonged mechanical tension. Drug-free microneedle (MN) patches were developed to dissipate this tension using biopolymeric complexes of whey protein isolate (WPI) with chitosan (CS) or trimethyl chitosan (TMC). Four CS/WPI or TMC/WPI blends were solvent-cast into films and screened for tensile strength, solvent uptake and bioadhesion; the two leading formulations were mould-cast into 10 × 10 pyramidal MN arrays, one 600 μm depth and the other one 800 μm depth. Each array resisted ≥ 0.17 N per needle and pierced a stratum-corneum surrogate without fracture, fulfilling the mechanical requirements for safe cutaneous insertion. TMC-based MNs dissolved > 90 % within 30 min, whereas CS-based MNs swelled twenty-fold and lost 50 % mass over six days, enabling rapid and sustained mechanotherapeutic profiles, respectively. In fibroblast-populated collagen lattices both MN types reduced matrix contraction and storage modulus by 20–30%, indicating effective disruption of pro-fibrotic mechanotransduction. Subcutaneous implantation in mice for 18 days evoked neither inflammation nor foreign-body response and supported complete epidermal and dermal regeneration. These findings demonstrate that CS/WPI- or TMC/WPI-based MN patches combine reliable skin penetration with tunable dissolution to provide a minimally invasive, patient-friendly means of attenuating hypertrophic and keloid scar formation. Further optimisation and clinical studies are warranted to realise the translational potential of this drug-free platform.