Abstract
BackgroundBasic fibroblast growth factor (bFGF) plays an important role in promoting wound healing and reducing scar, but the possible molecular mechanisms are still unclear. Our previous studies have found that activating the Notch1/Jagged1 pathway can inhibit the differentiation of epidermal stem cells (ESCs) to myofibroblasts (MFB). Herein, we document that bFGF reduces scar by inhibiting the differentiation of ESCs to MFB via activating the Notch1/Jagged1 pathway.MethodsIn in-vitro study, ESCs were isolated from 10 neonatal SD rats (1–3 days old), cultured in keratinocyte serum-free medium, and divided into six groups: bFGF group, bFGF + SU5402 group, bFGF + DAPT group, siJagged1 group, bFGF + siJagged1 group, and control group. Jagged1 of the ESCs in the siJagged1 group and bFGF + siJagged1 group was knocked down by small-interfering RNA transfection. Expression of ESC markers (CK15/CK10), MFB markers (α-SMA, Collagen I, Collagen III), and Notch1/Jagged1 components (Jagged1, Notch1, Hes1) was detected by FCM, qRT-PCR, and western blot analysis to study the relationships of bFGF, ESCs, and Notch1/Jagged1 pathway. In in-vivo study, the wound healing time and scar hyperplasia were observed on rabbit ear scar models. The quality of wound healing was estimated by hematoxylin and eosin staining and Masson staining. Expression of ESC markers, MFB markers and Notch1/Jagged1 components was elucidated by immunohistochemistry, immunofluorescence, and western blot analysis.ResultsThe in-vitro study showed that bFGF could significantly upregulate the expression of ESC markers and Notch1/Jagged1 components, while downregulating the expression of MFB markers at the same time. However, these effects could be obviously decreased when we knocked down Jagged1 or added DAPT. Similarly, in in-vivo study, bFGF also exhibited its functions in inhibiting the differentiation of rabbit ESCs to MFB by activating the Notch1/Jagged1 pathway, which improved the wound healing quality and alleviated scar significantly.ConclusionThese results provide evidence that bFGF can reduce scar by inhibiting the differentiation of ESCs to MFB via the Notch1/Jagged1 pathway, and present a new promising potential direction for the treatment of scar.
Highlights
Basic fibroblast growth factor plays an important role in promoting wound healing and reducing scar, but the possible molecular mechanisms are still unclear
To confirm the effect of Basic fibroblast growth factor (bFGF) on Epidermal stem cell (ESC) differentiation to MFB, we tested the expression of α-Smooth muscle actin (α-SMA), CK10, and CK15 by Flow cytometry (FCM), and detected the expression of α-SMA, Collagen I (Col I), and Collagen III (Col III) by Quantitative real-time PCR (qRT-PCR) and western blot analysis
The ratio of CK15 and CK10 reflects the purity of ESCs: the higher the ratio, the higher the purity [23, 24]. α-SMA is a specific marker of MFB and Col I and Col III are metabolites of MFB, and they were used to show the differentiation of ESCs to MFB [25, 26]
Summary
Basic fibroblast growth factor (bFGF) plays an important role in promoting wound healing and reducing scar, but the possible molecular mechanisms are still unclear. Our previous studies have found that activating the Notch1/Jagged pathway can inhibit the differentiation of epidermal stem cells (ESCs) to myofibroblasts (MFB). We document that bFGF reduces scar by inhibiting the differentiation of ESCs to MFB via activating the Notch1/Jagged pathway. ESCs keep the normal structure and function of skin and repair damage by proliferation, migration, and differentiation [6]. We found that the number of ESCs in scar was significantly lower than in normal skin, while MFB were significantly higher [8]. This phenomenon implied that the proliferation decrease and abnormal differentiation of ESCs can be an important reason for scar
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