急性放射性皮肤溃疡中血小板源性生长因子及其受体的表达

目的观察不同创面血小板源性生长因子(PDGF)A及其受体(PDGFR)α的动态表达,探讨急性放射性皮肤溃疡难愈合的机制。方法应用γ射线单次照射Wistar大鼠,制作急性放射性皮肤溃疡模型(照射组,55只),以皮肤全层切割伤模型大鼠作为创伤对照(创伤组,55只),另取5只正常大鼠作为对照组。采用免疫组织化学及原位逆转录-聚合酶链反应(RT-PCR)等方法,观察不同时相点各组大鼠创面内PDGF-A、PDGFR-α和PDGF-AmRNA的表达。结果对照组大鼠皮肤中PDGF-A及PDGFR-α表达为阴性;创伤组大鼠炎症反应期及肉芽组织期(伤后3~9d)PDGF-A的积分吸光度(IA)值为20.0±1.6、28.3±1.0;照射组炎症反应期及肉芽组织期(伤后14~28d)其PDGF-A的IA值各为14.0±1.2、20.3±1.2,PDGF-A及PDGFR-α和PDGF-AmRNA的表达较创伤组明显减弱,至瘢痕形成期(伤后55d)时表达进一步减弱。结论急性放射性皮肤溃疡内PDGF-A及PDGFR-α的表达减弱,可能是创面难愈合的机制之一。

The expression of platelet-derived growth factor-A and its receptor in acute radiation-induced skin ulcer in rats

OBJECTIVE: To investigate the dynamic expression of platelet-derived growth factor-A (PDGF-A) and its receptor alpha (PDGFR-alpha) in different acute radiation-induced skin ulcers, and to explore the underlying mechanism involved in retarded healing of the ulcer. METHODS: The model of acute radiation-induced skin ulcers in rats was replicated with 50 Gy 60Co gamma rays to the skin (radiation group, R, n = 55), rats with full - thickness skin excision wounds as control group (T, n = 55), and 5 normal rats to serve as normal control (NC) group. The expression of PDGF-A and PDGFR-alpha protein and PDGF-A mRNA was respectively assessed by means of histochemistry and in situ RT-PCR. RESULTS: No PDGF-A expression was identified in the rat skin in NC group. The expression of PDGF-A and PDGFR were reduced in R group during inflammatory responsive and granulation formation periods (14 - 28 days after radiation, the IA value of PDGF-A varied from 14.0 +/- 1.2 to 20.3 +/- 1.2 compared with that in T group in which the IA value of PDGF-A at the same period (3 - 9 days after injury) varied from 20.0 +/- 1.6 to 28.3 +/- 1.0, and reduced gradually during scar formation period (55 days after radiation). CONCLUSION: The reduction of PDGF-A and PDGFR-expression may be partially involved in the mechanism of retarded healing of acute radiation-induced skin ulcers.