Abstract

Platelet-rich plasma (PRP) is widely utilized for skin rejuvenation and tissue regeneration; however, its biological effects vary according to leukocyte content and molecular composition. We investigated the mechanism by which leukocyte-rich PRP (L-PRP) enhances extracellular matrix (ECM) regeneration in aged skin, focusing on the CCL1-CCR8/pyruvate kinase M2 (PKM2) signaling axis. First, we demonstrated that L-PRP contains significantly higher levels of CCL1 than platelet-poor plasma (PPP). In senescent human dermal fibroblasts, L-PRP increased CCL1-CCR8 interactions in a manner linked to enhanced formation and nuclear translocation of PKM2 dimers. This enhancement was accompanied by Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) pathway activation and the upregulation of STAT3-dependent anti-apoptotic proteins (Bcl-2, Bcl-xL) and proliferative markers (Cyclin D1), resulting in increased fibroblast proliferation. Furthermore, L-PRP increased PKM2 tetramer levels, promoted PKM2-SMAD7 binding, and reduced SMAD7-mediated inhibition of transforming growth factor (TGF)-β signaling, leading to enhanced SMAD2/3 activation. These molecular events augmented the synthesis of collagen types I and III in senescent fibroblasts. In aged mice, intradermal L-PRP injections elicited dose-dependent increases in fibroblast proliferation, collagen fiber deposition, and skin elasticity. Nuclear PKM2 dimer/STAT3 signaling and PKM2 tetramer/TGF-β signaling were both more strongly activated in the L-PRP group. Our findings identify PKM2 as a central metabolic and signaling integrator linking immune-derived chemokines to fibroblast rejuvenation. This study provides mechanistic insights concerning how L-PRP promotes ECM regeneration in aged skin via coordinated regulation of fibroblast survival, proliferation, and collagen synthesis.

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