diseases， and facilitating the formation of malignant tumors. Fibroblasts in the dermis are categorized into
papillary fibroblasts （Fp） and reticular fibroblasts （Fr）， crucial for skin regeneration. The present study elucidates that
photodamage leads to alterations in different subtypes of Fb， and addresses this phenomenon to find a therapeutic strategy that
can repair photodamage. Methods A mouse model of skin photodamage was established and biological specimens were
collected for subsequent analyses， including HE and Masson staining to evaluate tissue structure， DHE staining to detect
ROS levels in tissues，γH2AX staining to identify cells with DNA damage， immunofluorescence staining for Lrig1 and Dlk1
to identify distinct Fb subtypes. Furthermore， UVB was used to induce and culture fibroblasts， followed by flow cytometry to
detect surface markers， and qPCR to assess mRNA expression related to collagen synthesis and secretion. Lrig1 and DHE，
γH2AX fluorescence staining was respectively performed in in vitro assays and in vivo photodamage models by applying
ZnCS-configured ionic solutions and microneedle patch interventions loaded with ZnCS. Results In photodamaged skin，
the dermis exhibited infiltrative inflammatory cells and disrupted collagen fiber structure with reduced content， accompanied
by a significant increase in ROS expression throughout the epidermis and superficial dermis， accompanied by more DNA
damage in superficial dermal fibroblasts. Compared to the control group， there was a marked reduction in Lrig1+Fb cells
within the photodamaged skin dermis， while no significant difference was detected in Dlk1+Fb cells. Following UVB
irradiation of fibroblasts， flow cytometry analysis revealed a substantial decrease in the proportion of Lrig1+Fb cells among the
fibroblasts. Additionally， downregulation of COL1A1 expression was noted， alongside upregulation of MMP3 and MMP9
expressions. Finally， silicate bioceramics （ZnCS） promoted Fp proliferation， and ROS generation and damage in
photodamaged skin were significantly reduced after intervention with ZnCS. Conclusion Fp reducing is associated with the
progression of photodamage to photoaging. Meanwhile， ZnCS， which has a promoting effect on Fp proliferation， exerts a
significant repairing effect on photodamaged skin.
