Keratin Rich <scp>PCL</scp> Blended Nano‐Microfibrous Sheet as a Bioactive Immunomodulatory <scp>ECM</scp> Analog Toward Dermal Wound Healing—In Vitro and In Vivo Responses

Being an excretory scleroprotein, human hair-derived keratin with inherent bioactive peptide cues may actively participate in an immunomodulatory role in the wound microenvironment. In the current study, nano-microfibrous structural attributes mimicking the extracellular matrix were prepared using a polymer blend containing a high loading of keratin as a bioactive matrix by electrospinning, where polycaprolactone (PCL) was used as an electrospinnable aid. The FESEM analysis showed smooth fibers with diameters ranging from 100 to 220 nm. High keratin loading facilitated improved cellular affinity due to the presence of bioactive peptide cues. Physico-chemical characterization confirmed the presence of protein within the PCL matrix, and the modulus of the material (~25 MPa) was found to be similar to that of native skin. Furthermore, keratin-rich matrices evidenced the potential to modulate macrophages toward M2 macrophages. In vitro assessment with human dermal fibroblasts (HDFs) demonstrated enhanced cytocompatibility-like cellular activity and cell proliferation. In vivo studies evidenced the proactive role of the KPCL matrix in supporting full-thickness wound healing and balancing macrophage activity (CD68 and CD206 immunostaining). Immunohistochemistry and RT-PCR studies showed increased COLI and COLIII expression, evidencing dermal reconstruction within 18 days. Enhanced P63 and K14 expression supported the synergistic role of reepithelialization by the matrix enriched with keratin. Overall, the study showed that the keratin-based matrix facilitates skin wound healing.