碱性成纤维细胞生长因子对兔耳创面愈合过程中瘢痕形成的影响

目的 探讨碱性成纤维细胞生长因子(bFGF)对兔耳瘢痕模型的影响作用.方法 建立48个兔耳增生性瘢痕模型,将其随机分为bFGF治疗组与磷酸盐缓冲液(PBS)对照组,观察bFGF对创面愈合过程中瘢痕形成的影响.结果 形态学分析结果显示治疗组3个月后瘢痕外观、厚度及质地均优于对照组,表现出良好的愈合质量;对照组羟脯氨酸(HPr)表达较高,且随时间表现为增高趋势,伤后3个月达到高峰;而bFGF治疗组HPr表达均有不同程度的下降;逆转录-聚合酶链反应(RT-PCR)结果显示bFGF可以抑制CO Ⅰ mRNA的表达,但对COⅢmRNA表达无明显影响;Western blot结果显示bFGF可以促进MMP-1的合成,且随着时间延长表现为增高趋势,具有一定的时间相关性.结论 bFGF可以通过增加MMP-1合成、促进胶原蛋白降解而减少瘢痕的形成.     

The effect of the angiogenesis inhibitor, angiostatin, on hypertrophic scarring

Introduction: Hypertrophic scarring is commonly seen by plastic surgeons in China. Since the etiology of hypertrophic scarring is still unknown, the only reliable treatment is surgical excision. To understand if angiogenesis plays an important role in the formation of hypertrophic scars, we investigated the effect of angiostatin, a potent angiogenesis inhibitor, on hypertrophic scar formation. Our hypothesis is that angiogenesis is required for increased scar formation and angiogenesis inhibition may be one of the methods that can be used to prevent the formation of hypertrophic scars. Methods: We have developed a reliable model in rabbits that results in hypertrophic scarring by creating a 6mm x 6mm full thickness skin wound on both ears. The cDNA for angiostatin is cloned into the pcDNA 3.1 mammalian expression vector. After the wounds re-epithelialized but prior to excessive scarring, the angiostatin expression vector was injected with Lipofectin 2000 once every two days. The expression of angiostatin was confirmed by RT-PCR. The scar tissue was harvested 14 days after injection and processed for histology and total protein. Histology was examined with routine stains, the amount of collagen deposition in the scar tissue was detected by proline assay, and TGF-β1 and VEGF expression was detected by western blot. Results: Compared to the control injection scar, the injection of angiostatin led to a much more normal-looking of scar in the rabbit ear. The proline assay demonstrated that the injection of the angiostatin expression vector resulted in much less collagen in the scar tissue. Western blot analysis showed there was less TGF-β1 and VEGF protein expression in the treated ear compared to the control. Conclusion: The introduction of a vector over-expression angiostatin can result in the decreased formation of hypertrophic scars in a rabbit ear model. This is corroborated by evidence of decreased collagen deposition, the primary extracellular matrix component of scars. In addition, we demonstrate the decreased expression of τηε pro-fibrosis growth factor, TGF-1, and the potent angiogenic factor, VEGF. These data suggest that angiogenesis inhibitors may have a potential role in the treatment of hypertrophic scarring.     

15-脱氧-△^12,14-前列腺素J2对兔耳增生性瘢痕的作用

目的探讨γ过氧化物酶体增殖物激活受体（peroxisome proliferator activated receptor-7,PPAR-γ）的配体15-脱氧-△^12,14-前列腺素J2（15-deoxy-△^12,14-prostagliandxinJ2,15d—PGJ2）对兔耳增生性瘢痕I型胶原、结缔组织生长因子（connective tissue growth factor,CTGF）、α平滑肌肌动蛋白（a—smooth muscle actin,α—SMA）表达的影响,探讨15d—PGJ2防治增生性瘢痕的可能性。方法选取新西兰大白兔18只,在兔耳腹侧面制作2cm×3cm全层皮肤缺损创面,每耳2个,共计72个,建立兔耳增生性瘢痕动物模型,随机分为2组,一组为实验组,另一组为对照组,分别用15d—PGJ2和生理盐水行瘢痕内注射,1次／d,共7次。停药后第7、14、21天两组同时取材;每组每次切取12个组织块。应用免疫组织化学检测I型胶原、CTGF和α—SMA的表达。结果各组兔耳腹侧创面愈合后均不同程度出现类似人增生性瘢痕的组织块。与对照组相比,15dPGJ2注射后瘢痕体积缩小,变软变平,色泽轻度变浅。在各个时间点15d—PGJ2组I型胶原、CTGF和α-SMA的表达均较对照组低,且差异有统计学意义（P〈0．05）。结论PPAR-γ的配体15d—PGJ2可降低瘢痕内I型胶原、CTGF和α—SMA的含量,引起瘢痕萎缩,有一定防治瘢痕的作用,可能为临床治疗增生性瘢痕提供一条新的途径。     

ALA-PDT对兔耳增生性瘢痕抑制效应及作用机制的初步研究

目的：观察ALA-PDT（5-氨基酮戊酸光动力疗法）对兔耳增生性瘢痕形成的抑制作用及对转化生长因子β1（TGF-β1）表达的影响。方法：在兔耳腹侧面做直径1cm大小全层皮肤缺损创面3个/侧,共60个。随机分为以下三组：高浓度ALA-PDT组（n=20）：20%ALA介导PDT治疗;低浓度ALA-PDT组（n=20）：10%ALA介导PDT治疗;对照组（n=20）：不做治疗,待创面自然愈合。在创面形成术后的第6天、第13天分别进行ALA-PDT治疗,观察治疗组与对照组之间的瘢痕形成率、瘢痕增生指数、胶原纤维含量及TGF-β1表达情况的差异。结果：ALA-PDT治疗降低了瘢痕形成率,其中药物高浓度ALA-PDT组与对照组的差异有统计学意义（P〈0.01）;药物高浓度ALA-PDT组和药物低浓度ALA-PDT组的瘢痕增生指数、胶原纤维含量与对照组的差异有统计学意义（P〈0.05）;药物高浓度ALA-PDT组与对照组之间的TGF-β1的表达差异具有统计学显著性（P〈0.05）。结论：ALA-PDT对兔耳增生性瘢痕的形成有抑制作用,从而预防创伤后增生性瘢痕形成,该作用可能通过减少TGF-β1的产生而实现。     

Inhibition of prolyl 4-hydroxylase reduces scar hypertrophy in a rabbit model of cutaneous scarring

Hypertrophic scars result from excessive collagen deposition at sights of healing dermal wounds and can be functionally and cosmetically problematic. Pharmacological regulation of collagen synthesis and deposition is a direct approach to the control of scar tissue formation. We tested the ability of the phenanthrolinone derivative FG-1648 (in 0.5% Carbopol 971 PNF gel, pH 6.5), a prolyl 4-hydroxylase inhibitor, to reduce hypertrophic scar formation in a rabbit ear hypertrophic scar model. New Zealand White rabbits were divided into two treatment groups (n = 12 wounds per group with an equal number of controls): low-dose group: 0.5% FG-1648; high-dose group: 1% FG-1648. Left ears were used for treatment and right ear for control. Four 7-mm dermal ulcer wounds were made on each ear. The inhibitor was topically applied to the wound at the time of wounding and once daily up to postoperative day 7. Wounds were harvested at postoperative day 28 and scar hypertrophy quantified by measurement of the scar elevation index. All wounds showed complete healing. Treatment of wounds with 1% prolyl 4-hydroxylase inhibitor decreased the scar elevation index by 26% compared to control wounds (p < 0.01). Wounds treated with 0.5% FG-1648 inhibitor showed no difference in scar elevation compared to control wounds. These results suggest that inhibition of prolyl 4-hydroxylase may be a suitable agent for topical treatment for the prevention of hypertrophic scar tissue.     

兔耳解剖特点与成功建立增生性瘢痕模型的相关性实验研究

目的 观察兔耳不同部位的解剖结构特点,探讨不同手术方式以及术后处理方法对兔耳增生性瘢痕形成的影响,为成功建立增生性瘢痕动物模型提供理论依据.方法 新西兰白兔25只,切取5只兔10只耳60份全层组织标本,进行正常组织学观察;20只兔40只耳,每只兔耳腹侧各建立直径为8mm的全层皮肤缺损6个,总计240个创面.其中10只兔120个创面随机分为4组,手术后7d给予不同处理;另外10只兔120个创面术后不做处理.连续观察创面愈合以及瘢痕增生情况6个月,分别于手术后4、8周留取瘢痕组织行病理学检查和测量瘢痕增生指数.结果 正常兔耳不同部位的解剖结构特点不一致;建立兔耳瘢痕模型,部位宜选择在双侧兔耳腹侧内侧缘中、下侣部位,创伤深度宜破坏软骨膜,瘢痕形成率高,瘢痕增生指数高,持续时间长;术后剥痂可促进创面愈合,不利于瘢痕形成与增生.结论 兔耳自身的解剖结构特点与成功建立增生性瘢痕模型有一定的相关性,选择合适的建模部位、合理的创伤深度、术后恰当的处理均可影响瘢痕的形成和增生程度,可以提高增生性瘢痕建模成功率.     

A型肉毒毒素局部应用对兔耳增生性瘢痕创面愈合和瘢痕增生的影响

目的 研究A型肉毒毒素对兔耳增生性瘢痕组织的影响.方法 8只日本大耳白兔,体重3 kg,建立兔耳增生性瘢痕模型.将兔耳创面分为A型肉毒毒素治疗组(T组)和瘢痕组(S组),每组48个创面.大体观察创面愈合时间和瘢痕增生情况.术后28 d,同法另取4只兔子的兔耳腹面健康皮肤为空白组(B组),收集标本.测量S、T组标本HE切片的瘢痕增生指数HI,流式细胞仪分析2组标本中成纤维细胞的细胞周期,western-blot检测S、T、B组标本中Ⅰ、Ⅲ型胶原的蛋白表达.结果 ①T组标本的瘢痕增生指数HI较S组显著降低,P<0.01;②蛋白水平上,T组的胶原Ⅰ、Ⅲ蛋白表达和胶原Ⅰ/Ⅲ比值均较s组显著降低,P<0.01;③S组分布于G2-M期和S期的成纤维细胞较T组显著增多,而静止期G0-G1的细胞则显著减少,P<0.05.结论 A型肉毒毒素局部应用能抑制兔耳增生瘢痕的形成.抑制成纤维细胞的增殖活性,减少瘢痕组织中Ⅰ、Ⅲ型胶原的合成,降低胶原Ⅰ/Ⅲ比值,为其治疗增生性瘢痕的临床应用提供了一定的理论依据.     

Temporal expression of the transforming growth factor-Beta pathway in the rabbit ear model of wound healing and scarring

BACKGROUND: Despite numerous studies that have investigated the cellular and molecular mechanisms underlying scar formation, this process still remains poorly understood. The importance of transforming growth factor-beta (TGF-beta) in these processes has been well recognized, and this study sought to define the temporal expression of the key members in this pathway in a well-established, clinically relevant, rabbit ear model of hypertrophic scarring. STUDY DESIGN: Seven-millimeter (hypertrophic) and 5-mm (nonhypertrophic) punch wounds were made on the ears of 12 rabbits. Wounds were harvested at days 0, 7, 15, 28, and 40. RESULTS: There were no appreciable histologic differences between the 5- and 7-mm wounds at days 7 and 15. At day 28, however, the 7-mm scars were considerably more hypertrophic compared with the 5-mm control scars (p<0.001). The mRNA levels of TGF-beta1 and collagen Ialpha2 were notably higher in the hypertrophic 7-mm scars at day 28 than in the nonhypertrophic 5-mm scars (p<0.03). Although not pronounced, levels of TGF-beta2 were higher in the hypertrophic scars. There were no other statistically significant differences between the 7- and 5-mm scars. CONCLUSIONS: Elevated levels of TGF-beta1, and possibly TGF-beta2, are associated with hypertrophic scar formation.     

Adenovirus-mediated METH1 gene expression inhibits hypertrophic scarring in a rabbit ear model

Hypertrophic scarring remains a major problem for patients who have suffered from surgeries or burns. Vascularization plays an important role in the early phase of hypertrophic scarring. Therefore, the inhibition of angiogenesis might be used as a preventive strategy. In this study, we assessed the effect of anti-angiogenesis resulting from adenovirus-mediated METH1 (metalloprotease and thrombospondin1) gene expression on the hypertrophic scar formation in a rabbit ear model of hypertrophic scarring. We first investigated the number of microvessel and microcirculatory perfusion in untreated scars on days 10, 30, 60, and 90 after epithelialization. Then, we examined the effect of anti-angiogenesis by adenovirus-mediated METH1 expression on hypertrophic scar formation by calculating the scar elevation index, counting the microvessel and argyrophilic nucleolar organizer region particle, and detecting the amount of collagen on days 30 and 60 after treatment. We found that untreated scar tissues at the proliferative phase (days 10–60 after epithelialization) had a significantly higher density of microvessel and microcirculatory perfusion than those at the mature phase (day 90 after epithelization) (both p <0.05). On days 30 and 60 after treatment, the hypertrophic scar formation was significantly inhibited in the treatment group. There was significantly reduced scar elevation index, microvessel count, number of argyrophilic nucleolar organizer region, and total collagen content for treated scars. Our results demonstrate that METH1 has a markedly inhibitive effect on the formation of hypertrophic scar, and may thus have a promising application in the prevention of human hyperthropic scars.     

血小板衍生生长因子对成纤维细胞合成胶原的影响

目的 探讨血小板衍生生长因子（ＰＤＧＦ－ＡＢ）促进伤口愈合的作用机理及其在瘢痕增生中的作用。方法 取体外培养的人正常皮肤及增生性瘢痕成纤维细胞,用原位杂交法观察ＰＤＧＦ对两种细胞表达Ｐｒｏα１（Ⅲ）ｍＲＮＡ的影响。结果;ＰＤＧＦ－ＡＢ对两种成纤维细胞表达Ｐｒｏ α１（Ⅲ）ｍＲＮＡ均有明显促进作用,且均呈剂量依赖性关系,但作用有差异。     

15-脱氧-△12,14-前列腺素J2对兔耳增生性瘢痕Ⅰ型胶原表达的影响

目的 观察过氧化物酶体增殖物激活受体γ(PPARγ)的配体15-脱氧-△12,14-前列腺素J2(15d-PGJ2)对兔耳增生性瘢痕Ⅰ型胶原表达的影响,探讨15d-PGJ2防治增生性瘢痕的可行性.方法 选取新西兰大白兔18只,在兔耳腹侧面制作2 cm×3 cm全层皮肤缺损创面,每耳2个,共计72个,建立兔耳增生性瘢痕动物模型,随机分组,分别用15d-PGJ2及生理盐水行瘢痕内注射,1次/d,共7次.停药后第14、21天两组同时取材;每组每次切取18个组织块.应用免疫组织化学、荧光定量聚合酶链反应(PCR)及Western blot检测Ⅰ型胶原的表达.结果 与对照组比较,15d-PGJ2注射后瘢痕体积缩小,变软变平,色泽轻度变浅.Ⅰ型胶原主要分布于真皮的细胞间质、成纤维细胞胞质中,血管壁上亦见阳性信号,在各个时间点15d-PGJ2组Ⅰ型胶原mRNA和蛋白的表达均较对照组低,且差异有统计学意义(P<0.05).结论 PPAR-γ的配体15d-PGJ2可降低瘢痕内Ⅰ型胶原的含量,引起瘢痕萎缩,从而防治瘢痕.     

Control of wound contraction. Basic and clinical features

Although a substantial amount of molecular and cellular data have been generated in an effort to understand the process of wound contraction and scar contracture formation, questions remain. What seems apparent is that the myofibroblast is not the only cell that generates contractile forces within wounds, but it does appear to be intrinsically linked to the development of hypertrophic scars. The supposition that the formation of scar contractures is solely the result of a continuation of wound contraction is an oversimplification. Figure 4 provides a model of the possible evolution of contractile forces during the wound healing process and their role in the development of scar contractures. Migration of fibroblasts into and through the extracellular matrix during the initial phase of wound healing, prior to the expression of alpha-SMA, appears to be a fundamental component of wound contraction. During this migration, the pulling of collagen fibrils into a streamlined pattern in their wake, and the associated production of collagenase, may facilitate a more normal arrangement of collagen. Once the wound has been repopulated and the chemotactic gradient that was established by inflammatory cells is decreased, fibroblast migration will cease. It is at this point that myofibroblasts appear and play a key role in the production of hypertrophic scars, given that their prolonged presence and over-representation are hallmarks of this pathology. One of the pivotal differences between wounds that proceed to normal scar compared with those that develop hypertrophic scars and scar contractures may be a lack (or late induction) of myofibroblast apoptotic cell death. The combined contribution of fibroblasts and myofibroblasts to abnormal extracellular matrix protein production results in an excessive and rigid scar. The isometric application of contractile forces by myofibroblasts probably contributes to the formation of the whorls, nodules, and scar contractures characteristic of hypertrophic scars. Because the prolonged presence of myofibroblasts, producing an imbalance in extracellular matrix proteins and proteases, probably exacerbates hypertrophic scars and wound contraction, accelerating the rate of apoptotic cell death to reduce the cell number to that seen in normal scar may be a useful strategy for providing effective and efficient treatment of scar contracture.     

瘢痕内注射脂肪来源干细胞对兔耳增生性瘢痕的抑制作用研究

目的 研究瘢痕内注射脂肪来源干细胞(ADSC)对兔耳增生性瘢痕的抑制作用及可能机制。方法 选取12只新西兰大白兔,制作兔耳增生性瘢痕模型,随机平均分成3组,2周后各组右耳瘢痕内注射DMEM作为自身对照,左耳分别注射ADSCs、脂肪来源干细胞条件培养基(ADSCs-CM)及不作处理。注射前及注射后1、2、3周检测瘢痕增生情况,并于注射后3周取材,行组织化学及基因学检测。结果 造模2周后,伤口均完全上皮化;DMEM注射及未处理组的伤口逐渐出现增厚、变红、变硬等增生表现,注射后3周时最为明显;ADSCs及ADSCs-CM注射组均未出现明显增生反应。取材后HE、Masson染色示,ADSCs及ADSCs-CM注射组瘢痕的胶原密度适中、排列整齐;对照及未处理组瘢痕可见大量致密、杂乱的胶原组织。基因检测发现,ADSCs及ADSCs-CM注射组瘢痕的α-SMA、CollagenⅠ表达显著低于对照及未处理组。ADSCs注射组瘢痕冰冻切片Dil荧光染色可见大量存活脂肪来源干细胞。结论 瘢痕内注射脂肪来源干细胞可以降低α-SMA、CollagenⅠ基因表达,从而改善瘢痕内胶原堆积,并最终改善瘢痕增生情况。     

The temporal effects of anti-TGF-beta1, 2, and 3 monoclonal antibody on wound healing and hypertrophic scar formation

BACKGROUND: A number of studies have implicated transforming growth factor (TGF)-beta1, 2, and 3 (TGF-beta) in wound healing and hypertrophic scarring. We propose that TGF-beta has a temporal effect on these processes. To test this hypothesis, we applied anti-TGF beta1, 2, and 3 monoclonal antibody topically to our dermal ulcer model in the rabbit ear. STUDY DESIGN: Rabbit ear wounds were treated intradermally with anti-TGF-beta1, 2, and 3 antibody at early, middle, and late time points. Treated and untreated control wounds were harvested at various time points and examined histologically to quantify wound healing and scar hypertrophy. Real-time polymerase chain reaction was performed to determine TGF-beta mRNA expression in the treated and control wounds. RESULTS: The early treatment group demonstrated decreased new epithelium and granulation tissue (p < 0.05 versus controls). Scars harvested on days 28 and 40 displayed no difference in scar hypertrophy. Both the middle and late treatment groups demonstrated a significant decrease in scar hypertrophy (p < 0.05). CONCLUSIONS: Treated wounds from the early treatment group displayed delayed wound healing, with no reduction in scar hypertrophy. Later treatment of wounds with the same antibody, beginning 7 days after wounding, resulted in a reduction in scar hypertrophy. These results support our hypothesis and clearly demonstrate that TGF-beta1, 2, and 3 have differential temporal effects during the wound-healing process, and are important for optimal wound healing in the first week after wounding; beyond 1 week, TGF-beta1, 2, and 3 play a critical role in hypertrophic scar formation.     

The role of Th1/Th2 cell chemokine expression in hypertrophic scar

The aim of this study was to study the role of Th1/Th2 cell‐associated chemokines in the formation of hypertrophic scars in rabbit ears. Twenty‐six New Zealand white rabbits were used to establish the hypertrophic scar model of rabbit ear and the normal scar model of rabbit's back. Two rabbits were sacrificed on days 0 and 21, 28, 35, 42, 49, 56, and 63 after operation. The specimens were stained with haematoxylin‐eosin (HE). Scar elevation index (SEI) was used to detect the expression of 10 chemokines related to Th1/Th2 cells in both scar formation expressions. Real‐time polymerase chain reaction (PCR) results showed that two chemokines (CXCL10, CXCL12) were highly expressed during the formation of normal scar, and there was almost no expression during the formation of hypertrophic scar (*P < 0.05). The chemokines (CCL2, CCL3, CCL4, CCL5, CCL7, CCL13, CX3CL1) were almost non‐expressed in the formation of normal scars but were expressed for a long time in the formation of hypertrophic scars. The four chemokines, CCL2, CCL4, CCL5, and CX3CL1, maintained a long‐term high expression level during the formation of hypertrophic scars (P < 0.01). There were also three chemokines (CCL14, CCL19, CCL21) that were almost undetectable in normal scarring, but there was transiently low‐level expression (P < 0.05) only during the peak proliferative phase in proliferative scarring. Th1/Th2 cell‐associated chemokines are different in the type, quantity and expression, and maintenance time of rabbit ear hypertrophic scars.     

The effect of the anti-allergic agent avil on abnormal scar fibroblasts.

Abnormal wound healing in humans leads to the formation of hypertrophic scar and keloids. These abnormal scars accumulate excessive extracellular matrix proteins through increased synthesis as well as decreased degradation. In order to find a therapeutic control for scar formation, we investigated the effect of avil (pheniramine maleate) on fibroblasts cultured from abnormal scars in comparison to normal skin. We observed a decrease in the proliferation rate in cells from normal skin (39%), hypertrophic scar (44%), keloid (63%) and in DNA synthesis in cells from normal skin (50%), hypertrophic scar (55%) and keloid (63%) treated with 8 mM avil (72 h). The rate of decrease in collagen synthesis in normal skin (44%), hypertrophic scar (74%) and keloid fibroblast (73%) correlated with changes in DNA synthesis.     

Improvement of hypertrophic scarring by using topical anti‐fibrogenic/anti‐inflammatory factors in a rabbit ear model

This study investigates the scar‐reducing efficacy of topical application of stratifin and acetylsalicylic acid (ASA) in a rabbit ear model. A total of five New Zealand white rabbits with four wounds per ear were examined. Either recombinant stratifin (0.002%) or ASA (0.5%) incorporated in carboxymethyl cellulose gel was topically applied on each wound at postwounding Day 5. Scars were harvested at postwounding Day 28 for histological analysis. The wounds treated with stratifin and ASA showed 82 and 73% reduction in scar volume, respectively, compared with that of untreated controls. A reduction of 57 and 41% in total tissue cellularity along with 79 and 91% reduction in infiltrated CD3⁺ T cells were observed in response to treatment with stratifin and ASA, respectively, compared with those of untreated controls. Wounds treated with stratifin showed a 2.8‐fold increase in matrix metalloproteinase‐1 expression, which resulted in a 48% decrease in collagen density compared with those of untreated controls. Qualitative wound assessment showed a reduced hypertrophic scarring in stratifin and ASA‐treated wounds when compared with the controls. This study showed that topical application of either stratifin or ASA‐impregnated carboxymethyl cellulose gel reduced hypertrophic scar formation following dermal injuries in a rabbit ear fibrotic model.     

Expression profile of proteins involved in scar formation in the healing process of full-thickness excisional wounds in the porcine model

Scar formation in deep dermal wounds is associated with excessive collagen deposition and contraction. Increased collagen synthesis and decreased collagen degradation are the mechanisms through which this form of fibrosis can occur. Another factor might be a different kind of collagen cross-linking seen in fibrotic skin diseases. This type of cross-linking is dependent on the enzyme lysyl hydroxylase-2b. In this study, we examined the expression profile of the potential key players in scar formation in time in healing of acute wounds. Collagen types I and III, lysyl hydroxylase-2b, alpha-smooth muscle actin, transforming growth factor betas, and the matrix metalloproteinases and their inhibitor mRNA levels were determined. All genes examined show distinct expression patterns over time. The expression of lysyl hydroxylase-2b peaks at day 7, and precedes collagen types I and III expression. Eight weeks after wounding, the scars showed an increased level of lysyl hydroxylase-2b-mediated collagen cross-linking. This study shows that the fibrosis-specific type of cross-linking of collagen seen in human hypertrophic scarring also plays a role in this animal model of wound healing. Moreover, the expression of the putative gene responsible for this type of cross-linking, the lysyl hydroxylase-2b, is elevated during wound healing.