Stanford, Calif. From the Hagey Laboratory for Pediatric Regenerative Medicine, Department of Surgery, Stanford University School of Medicine.
Plast Reconstr Surg. 2010 Jan;125(1):74-88. doi: 10.1097/PRS.0b013e3181c495d1.
Mammalian fetal skin injury heals scarlessly. The intrinsic differences between embryonic and adult fibroblasts that underlie this observation are poorly understood. Several studies have linked Wnt proteins with skin morphogenesis. The authors' study aimed to establish a correlation between beta-catenin-dependent (canonical) Wnt protein, transforming growth factor (TGF)-beta1, and the expression of hyaluronan synthesis enzymes during scarless versus scarring wound healing.
Wnt signaling was quantified after 1.5-mm skin wounds were created in BAT-gal fetal (e16.5) and postnatal (p1) mice. Canonical Wnt signals were localized by X-gal staining and quantified with quantitative real-time polymerase chain reaction. Primary embryonic and postnatal mouse dermal fibroblasts were treated with recombinant Wnt3a or TGF-beta1. Proliferation was assayed by bromodeoxyuridine incorporation. Gene expression of enzymes that regulate hyaluronan production and turnover was examined by quantitative real-time polymerase chain reaction (hyaluronan synthases or HAS1-3, hyaluronadase-2), as well as other target genes for Wnt and TGF-beta (Axin2, TGF-beta1, TGF-beta3, type 1 collagen, proliferating cell nuclear antigen).
Canonical Wnt signaling increased following wounding in postnatal, but not fetal, mice. In vitro, rmWnt3a increased postnatal fibroblast proliferation but not in embryonic cells. Both Wnt3a and TGF-beta1 induced HAS2 and HAS3 gene expression in embryonic fibroblasts, while HAS1 and Hyal2 were induced in postnatal fibroblasts. Finally, rmWnt3a significantly increased type I collagen expression, particularly in postnatal fibroblasts, and influenced expression of TGF-beta isoforms.
Increased canonical Wnt signaling occurs during postnatal but not fetal cutaneous wound repair. Fetal and postnatal fibroblasts have a disparate response to rmWnt3a in vitro. rmWnt3a affects postnatal fibroblasts in a similar fashion to rhTGF-beta1, a known profibrotic cytokine.
哺乳动物胎儿皮肤损伤可无痕愈合。造成这一现象的胚胎和成纤维细胞之间内在差异的相关研究还不太清楚。有几项研究表明 Wnt 蛋白与皮肤形态发生有关。作者的研究旨在建立无瘢痕与瘢痕愈合过程中β-连环蛋白依赖性（经典）Wnt 蛋白、转化生长因子（TGF）-β1 和透明质酸合成酶表达之间的相关性。
在 BAT-gal 胎鼠（e16.5）和新生鼠（p1）皮肤中制造 1.5mm 皮肤伤口后，对 Wnt 信号进行定量。通过 X-gal 染色定位经典 Wnt 信号，并通过实时定量聚合酶链反应进行定量。用重组 Wnt3a 或 TGF-β1 处理原代胚胎和新生小鼠真皮成纤维细胞。通过溴脱氧尿苷掺入法测定增殖情况。通过实时定量聚合酶链反应（透明质酸合成酶或 HAS1-3、透明质酸酶-2）以及 Wnt 和 TGF-β 的其他靶基因（Axin2、TGF-β1、TGF-β3、I 型胶原、增殖细胞核抗原）检测调节透明质酸产生和转化的酶的基因表达。
新生鼠皮肤创伤后经典 Wnt 信号增加，但胎鼠无此现象。在体外，rmWnt3a 增加了新生成纤维细胞的增殖，但对胚胎细胞没有作用。Wnt3a 和 TGF-β1 均可诱导胚胎成纤维细胞 HAS2 和 HAS3 基因表达，而 HAS1 和 Hyal2 则在新生成纤维细胞中诱导表达。最后，rmWnt3a 显著增加 I 型胶原的表达，尤其是在新生成纤维细胞中，并影响 TGF-β 同工型的表达。
经典 Wnt 信号在新生鼠而非胎鼠皮肤创伤修复过程中增加。在体外，胚胎和成纤维细胞对 rmWnt3a 的反应不同。rmWnt3a 对新生成纤维细胞的作用类似于 rhTGF-β1，后者是一种已知的促纤维化细胞因子。
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