To investigate the effects of kunzea ericoides leaf extract on human dermal fibroblasts (HDFs) concerning the migration, proliferation, and collagen synthesis ability and to observe the impact of kunzea ericoides leaf extract on wound healing in rats.

After stimulation of kunzea ericoides leaf extract in different concentrations, assays of CCK-8 and Calcein/PI staining were applied to screen the optimal concentration of kunzea ericoides leaf extract on HDFs. The expression of Ki67 was detected to observe the proliferation ability of HDFs. Wound-healing assay was applied to detect the migration ability of HDFs after incubation with kunzea ericoides leaf extract. The expressions of typeⅠcollagen, type Ⅲ collagen, and α-smooth muscle actin were detected using the immunofluorescence and western blot assay, representing the collagen synthesis ability change of HDFs. The models of rat skin defect were established and treated with or without kunzea ericoides leaf extract, and the healing time was compared. Furthermore, the wound area tissue's morphology and collagen composition were observed using HE and Masson staining assays after complete healing.

The optimal concentration of kunzea ericoides leaf extract for HDFs was determined as 1% based on CCK-8 assay and Calcein/PI staining. In addition, the Ki67 expression was increased significantly [(0.71±0.16) vs (0.18±0.06), t=7.156, P<0.001], kunzea ericoides leaf extract enhanced the cell proliferation. The wound-healing assay confirmed that kunzea ericoides leaf extract improved the migration ability of HDFs. The results of the immunofluorescence and western blot assay showed that kunzea ericoides leaf extract increased the expressions of typeⅠcollagen, type Ⅲ collagen, and α-smooth muscle actin in HDFs [(43.22±7.58) vs (16.71±1.68), t=7.635, P<0.001; (46.62±5.90) vs (27.44±1.60), t=7.016, P<0.01; (1.32±0.14) vs (0.46±0.06), t=9.947, P<0.01], which meant kunzea ericoides leaf extract improved the collagen synthesis ability of HDFs. The healing time in the kunzea ericoides leaf extract group was (13.6±1.5)d, significantly shorter than (16.7±1.6)d of the control group (t=6.270, P<0.001). The results of HE and Masson staining suggested that after applying kunzea ericoides leaf extract, the skin tissue from the wound area resembled normal skin morphology and demonstrated more collagen deposition [(84.36±7.82) vs (67.72±5.24), t=5.595, P<0.001].

Kunzea ericoides leaf extract can promote the proliferation, migration, and collagen synthesis ability of HDFs, and might promote wound healing in rats by enhancing the function of dermal fibroblasts.