Micro-autotransplantation of the skin. Changes in size and morphology of neo-skin

A new technique of wide wound skin epithelialization by free transplantation of autologous skin fragments 1 mm2 in size is demonstrated. The experiments were carried out on strainless rats of different age, 100 per cent epithelialization of wound 5 mm2 in grafting skin micro-autotransplantation (MATR) was observed. The primary effectiveness of wound closing square to MATR square was 1:20. However, as a result of wound contraction the effectiveness (on neo-epidermis square) was finally 1:15 in old rats. During histological analysis hyperplasia of the epidermis was marked and decreased gradually. Skin MATR method is considered as organ-typical culture in vivo.     

Efficacy of mechanically modified electrospun poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactide-co-<Emphasis Type="Italic">ε</Emphasis>-caprolactone)/gelatin membrane on full-thickness wound healing in rats

Bioengineered skin substitute offers new opportunities for treating various skin ailments. To compensate the structural integrity problems of scaffolds prepared from natural components, we mechanically developed highly modified electrospun nanofibrous membranes, incorporating poly(l-lactide-co-ε-caprolactone) (PLCL) into gelatin [poly(l-lactide-co-ε-caprolactone)/ gelatin membrane, (P/G (3/7)]. Subsequent to our previous in vitro study, our goal was to evaluate the in vivo performance of PLCL, gelatin, and P/G (3/7) membranes, and investigate the feasibility of the newly developed P/G (3/7) membrane for wound healing. Histological analysis using the mathematical model of wound healing and contraction, revealed the association between stiffness of skin substitute with cytokeratin production and wound contraction rate, and the defect site covered with the stiffer membrane showed lower cytokeratin production, and inversely, higher wound contraction rate. Overall, the P/G (3/7) membrane induced a satisfactory wound healing outcome. However, lower cytokeratin production rate with the mechanically modified P/G membrane involves the importance of the conditional blending of PLCL. Conversely, the condition of PLCL showed some incompatibility and hindrance of skin regeneration, consistent with previous in vitro results. With proper mechanical strength and cell viability, the P/G (3/7) membrane could successfully be used as a suitable skin substitute scaffold.     

组织工程复合皮肤应用于皮肤缺损创面的临床疗效观察

目的:临床观察组织工程复合皮肤对烧伤整形后需植皮患者的供皮区缺损创面的有效性及安全性。方法:试验选取不同临床中心烧伤整形后需植皮患者,在供皮区部分创面作为试验区应用组织工程复合皮肤覆盖,邻近创面采用盐水纱布替代作为对照区,应用后按常规方法包扎固定。临床试验时间为6个月,治疗期间观察统计患者的创面反应,愈合时间及愈合情况;对组织工程复合皮肤改善创面愈合质量及安全性进行临床评估。根据创面试验组和对照组的创面愈合时间,应用SPSS统计软件对数据进行方差齐性检验,根据检验结果分别进行独立样本t或t’检验。结果:试验共收集有效病例19例。临床观察显示应用后试验区创面无明显免疫排斥及炎性反应,患者自述疼痛明显减轻,试验区创面愈合时间与对照区相比缩短8d,统计学分析有显著性差异。愈后随访部分患者试验区愈合质量好于对照区,应用后患者疼痛、瘢痕形成等不良反应明显减少。结论:结果表明组织工程复合皮肤作为活型皮肤替代物用于医源性皮肤缺损的修复,这为促进供皮区的创面愈合提供了切实可行的方法。     

The Mid-Atlantic Twin Registry.

The Mid-Atlantic Twin Registry (MATR) is a population-based registry of twin pairs ascertained from birth records and school system records of Virginia, North Carolina, and South Carolina. The MATR was formed in 1997 with the merging of the Virginia and North Carolina Twin Registries, and it expanded to include South Carolina when access to twin birth records in that state was granted in 1998. Registered twins ("participants") number more than 51,000, with approximately 46,000 of these individuals representing complete pairs. Roughly two-thirds of MATR participants are over age 18, with a mean age of approximately 35 years. These participants have primarily been drawn from the more than 170,000 identical and fraternal twin pairs born in the three states between 1913 and 2000. Twins and their family members have participated in numerous research projects, ranging from general health surveys to studies on specific health topics such as cardiovascular disease; depression and anxiety; seizures; behavioral development; pregnancy complications; conduct disorder; drug use, abuse, and dependence; cleft lip/palate; obesity; and chronic fatigue syndrome. The MATR has established a privacy policy and strict standard operating procedures to protect the confidentiality of participant data. The MATR considers a limited number of qualified requests per year from investigators interested in recruiting MATR participants into their research studies.     

生长激素在创面愈合中的应用

软组织损伤创面在合并糖尿病、放射治疗等情况下,常常延迟愈合、不愈、或反复发作,转变为慢性难愈性创面,成为长期困扰,临床治疗的一大难题。通常采用的皮肤移植疗法,无论自体还是异体皮都受到供体来源少的限制,异体皮和人工合成皮还存在免疫排斥等问题。生长激素在慢性创面愈合中的作用受到广泛关注,为慢性难愈创面的治疗提供了新的途径,有望带来突破性的治疗效果。     

Tension decrease during skin stretching in undermined versus not undermined skin: an experimental study in piglets

In a controlled study using 15 piglets, the efficacy of skin stretching using a skin stretching device was tested by quantifying the tension decrease during skin stretching in undermined and not undermined wounds. The viability of the skin margins was examined in both situations. Thirty standardized wounds was created: around 15 wounds on one flank, the surrounding skin was undermined; whereas around the 15 wounds on the opposite flank, the surrounding skin was not undermined. The force required to close the 9 x 9 cm defect was measured at the beginning, after undermining, and after 30 minutes of skin stretching. Also examined was the wound healing after 1 day and 1 week. A tension decrease of 3.02 N (13.6 percent reduction of the total force that is required to close the wound at the beginning) was seen due to undermining the surrounding skin. Skin stretching for 30 minutes without undermining the skin showed a tension decrease of 6.10 N (26.5 percent). Therefore, the tension decrease due to skin stretching was twice as high in comparison with undermining the skin margins alone. This has been statistically proven to be significant (-d (difference) = 3.08, 95 percent confidence interval = 2.16; 4.00, p < 0.001). When the undermined skin of the wound was stretched for 30 minutes, we measured a total tension decrease of 7.60 N (34.1 percent). There was a statistically significant but small difference in total tension decrease as a result of undermining combined with skin stretching in comparison with skin stretching without undermining (-d = 1.51, 95 percent confidence interval = 0.77; 2.23, p < 0.001). Undermining the surrounding skin involved cutting musculocutaneous perforating vessels. Looking at the viability of the skin, seven wounds, all found in the undermined group, showed skin necrosis after 1 week. Excessive seroma formation was seen in all wounds around which the skin was undermined. In the not undermined wounds, there were no problems in wound healing. In conclusion, skin stretching for only 30 minutes using a skin stretching device significantly reduces wound closing tension. The additional advantage of skin stretching over that of undermining alone is clearly shown. Undermining the wound margins before skin stretching gives a small additional tension decrease but has well-known complications, such as skin-edge necrosis and seroma formation.     

Repair of scalp defects using a tissue expander and Marlex mesh.

A simple technique using Marlex mesh and a tissue expander to cover scalp defects is described and two patients are presented. This technique is suitable for medium-sized defects that cannot be closed primarily. Marlex mesh is sutured to the wound edges in lieu of a temporary skin graft and to prevent enlargement of the defect during tissue expansion. The tissue expander is placed under adjacent normal scalp in a subgaleal pocket developed through the scalp defect. The scalp defect is closed secondarily using the expanded scalp flap. This technique was performed in two patients with satisfactory results. Marlex mesh obviates the need for a temporary skin graft to cover the scalp defect.     

Mechanics of scars

When a wound heals, as everyone has observed, it contracts, thickens and wrinkles the neighbouring skin, forming a scar. The morphology of the scar depends on the type of wound; an urgent tracheotomy leads to a very different scar than a carefully planned face lift. The surgical challenges of intrusive procedures such as removal of skin lesions, skin transplantation or grafting, and scar removal are complicated by the complex geometry and stress states in different parts of the body. We show that, for relatively general conditions, the nature of the localisation of the scar is determined by the background tension of the skin which can arrest the formation of wrinkles around a scar. Our physical experiments to simulate this procedure indicate that the region deformed by the defect has a characteristic length scale r* approximately 1 square root of tau, where tau is the natural tension of the skin.     

Leptin Promotes Wound Healing in the Skin

Introduction

Leptin, a 16 kDa anti-obesity hormone, exhibits various physiological properties. Interestingly, skin wound healing was proven to delay in leptin-deficient ob/ob mice. However, little is known on the mechanisms of this phenomenon. In this study, we attempted to elucidate a role of leptin in wound healing of skin.

Methods

Immunohistochemical analysis was performed to confirm the expression of the leptin receptor (Ob-R) in human and mouse skin. Leptin was topically administered to chemical wounds created in mouse back skin along with sustained-release absorbable hydrogel. The process of wound repair was histologically observed and the area of ulceration was measured over time. The effect of leptin on the proliferation, differentiation and migration of human epidermal keratinocytes was investigated.

Results

Ob-R was expressed in epidermal cells of human and mouse skin. Topical administration of leptin significantly promoted wound healing. Histological analysis showed more blood vessels in the dermal connective tissues in the leptin-treated group. The proliferation, differentiation/function and migration of human epidermal keratinocytes were enhanced by exogenous leptin.

Conclusion

Topically administered leptin was proven to promote wound healing in the skin by accelerating proliferation, differentiation/function and migration of epidermal keratinocytes and enhancing angiogenesis around the wounded area. These results strongly suggest that topical administration of leptin may be useful as a treatment to promote wound healing in the skin.     

Immunohistochemical study on Fas and Fas ligand in skin wound healing

An immunohistochemical study on the expression of Fas and Fas ligand (Fas L) was performed in order to examine the role of apoptosis through Fas–Fas L in mouse skin wound healing. After a 1-cm-long incision in the central dorsum skin, mice were sacrificed at intervals ranging from 0.5 to 240h, followed by the sampling of wound margin. The expression of Fas and Fas L in the wound margins and in uninjured skin controls was studied using frozen sections. In uninjured skin controls, a very weak expression of Fas and Fas L was detected immunohistochemically in hair follicles, sebaceous glands and epidermal cells. In wounded specimens, polymorphonuclear cells and inflammatory mononuclear ones (round-shaped and spindle-shaped types) were evident. A single immunostaining showed that Fas or Fas L was detectable in inflammatory mononuclear cells involved in the skin wound healing process. Double immunostaining for Fas and Fas L revealed that inflammatory mononuclear cells co-expressed both antigens. In situ TUNEL combined with immunostaining showed that the inflammatory mononuclear cells expressing Fas or Fas L and the polymorphonuclear cells were TUNEL-stained, although neither Fas nor Fas L was detected in the polymorphonuclear cells. The number of TUNEL-positive, inflammatory mononuclear cells expressing Fas or Fas L per 0.01×0.01cm² was counted. The average number of 10 randomly selected microscope fields reached a peak at the fibro-proliferative phase of wound healing. These results indicate that apoptosis through Fas and Fas L may play an important role for reducing the cellularity during skin wound healing in mice.     

新型持续皮肤牵张器促进皮肤创面愈合的实验研究

目的：介绍自主研制的持续皮肤牵张器,探讨自主研制的持续皮肤牵张器治疗皮肤缺损的可行性和效果分析。方法：自主研制的持续皮肤牵张器8套;白色家猪6只,将每只猪的背部（两侧）切除矩形皮肤软组织缺损,形成12个创面,分为二组,实验组4只猪8个创面,对照组2只猪4个创面,创面均为10cm×6cm,实验组创面用自制持续皮肤牵张器行皮肤伸展术治疗,对照组创面自行愈合。结果：实验组与对照组每日创面缩小面积相差较多,差异有统计学意义,实验组皮肤缺损行5-6天皮肤伸展术治疗后,可直接行二期缝合关闭,对照组1周后仍存在较大皮肤缺损,无法缝合关闭。结论：应用自制持续皮肤牵张器行皮肤伸展术,可以早期快速闭合皮肤创面。自制持续皮肤牵张器克服了以往牵张器的不足,具有使用方便,效果可靠,并发症少等优点,有良好的应用前景。     

Oxygenation and microcirculation during skin stretching in undermined and nonundermined skin

The aim of this experimental study was to assess the skin microcirculation of undermined and nonundermined wound edges closed with a skin-stretching device. In eight piglets, 9 x 9-cm wounds were created on both flanks by excision of the skin and the subcutaneous layer down to the muscular fascia, with general anesthesia. On one flank, the surrounding skin was completely undermined. For a period of 30 minutes, wound closure was performed with a stretching device, using the principle of load cycling. The device stretched the skin and moved the opposing wound edges toward each other. During this period, laser Doppler flowmetry and transcutaneous oximetry were simultaneously used to monitor microcirculation and oxygenation in the stretched skin of both flanks. Undermining of the surrounding skin produced a 12 percent decrease in the laser Doppler flowmetry signal and a 21 percent decrease in the transcutaneous oximetry value. Skin stretching resulted in decreases in the laser Doppler flowmetry signals and the transcutaneous oximetry values, whether or not the skin was undermined. Releasing the stretching device resulted in rapid normalization of the laser Doppler flowmetry values in undermined and nonundermined skin and a slow return of the transcutaneous oximetry values to close to baseline levels in nonundermined skin. The transcutaneous oximetry values in undermined skin did not return to baseline levels; each period of skin stretching resulted in an additional decrease in the transcutaneous oximetry values. Stretching of undermined skin for 30 minutes produced a significant (p < 0.0001) decrease in skin oxygenation. As a result, 50 percent of the undermined stretched skin demonstrated skin necrosis at the wound edges, which was still present after 1 week. Wound healing in the nonundermined stretched skin proceeded without problems. It is concluded from these experiments that the viability of undermined skin becomes compromised as a result of significantly decreased oxygen availability in the skin during and after stretching. Consequently, it is recommended that skin stretching be performed on nonundermined skin, rather than undermined skin. In addition, when skin is stretched to close a large defect, it is logical to use cyclic loading, so that recuperation of the skin circulation can occur. Furthermore, laser Doppler flowmetry seemed to produce atypical signals in monitoring of skin viability of wound edges closed with a skin-stretching device.     

Split-thickness skin grafting of the myelomeningocele defect: a subset at risk for late ulceration

The appropriate method and timing of the management of the myelomeningocele defect have prompted considerable discussion. Use of split-thickness skin grafts acutely has accomplished wound closure with low morbidity and mortality. This study was designed to address the question of long-term suitability of the technique of split-thickness skin grafting of the myelomeningocele patient. The incidence of late and/or severe skin ulceration and the presence of gibbus deformity were correlated with the method of skin closure. Long-term follow-up revealed a higher incidence of chronic skin ulceration in the split-thickness skin graft group as compared with the primary closure group. All skin breakdowns appeared in the presence of a gibbus deformity, and gibbus deformity was more prevalent in the split-thickness skin graft group. The incidence of skin ulceration and gibbus deformity was site-dependent. A thoracic or thoracolumbar myelomeningocele repair with split-thickness skin graft was significantly more likely to be complicated by skin problems than the defect in the lumbar, lumbosacral, or sacral region. This relationship was secondary to the frequency of gibbus deformity in the more cephalad defects than defects caudad. A treatment plan is outlined that is based on the primary variable of the location of the myelomeningocele and secondarily by defect size.     

beta-Adrenergic receptor antagonists accelerate skin wound healing: evidence for a catecholamine synthesis network in the epidermis

The skin is our primary defense against noxious environmental agents. Upon injury, keratinocytes migrate directionally into the wound bed to initiate re-epithelialization, essential for wound repair and restoration of barrier integrity. Keratinocytes express a high level of beta2-adrenergic receptors (beta2-ARs) that appear to play a role in cutaneous homeostasis as aberrations in either keratinocyte beta2-AR function or density are associated with various skin diseases. Here we report the novel finding that beta-AR antagonists promote wound re-epithelialization in a "chronic" human skin wound-healing model. beta-AR antagonists increase ERK phosphorylation, the rate of keratinocyte migration, electric field-directed migration, and ultimately accelerate human skin wound re-epithelialization. We demonstrate that keratinocytes express two key enzymes required for catecholamine (beta-AR agonist) synthesis, tyrosine hydroxylase and phenylethanolamine-N-methyl transferase, both localized within keratinocyte cytoplasmic vesicles. Finally, we confirm the synthesis of epinephrine by measuring the endogenously synthesized catecholamine in keratinocyte extracts. Previously, we have demonstrated that beta-AR agonists delay wound re-epithelialization. Here we report that the mechanism for the beta-AR antagonist-mediated augmentation of wound repair is due to beta2-AR blockade, preventing the binding of endogenously synthesized epinephrine. Our work describes an endogenous beta-AR mediator network in the skin that can temporally regulate skin wound repair. Further investigation of this network will improve our understanding of both the skin repair process and the multiple modes of action of one of the most frequently prescribed class of drugs, hopefully resulting in a new treatment for chronic wounds.     

Effect of fibroblast implants on wound healing of irradiated skin: assay of wound strength and quantitative immunohistology of collagen

The role of dermal fibroblasts in the expression of radiation-induced damage to the skin was studied. Fibroblasts from neonatal mice were cultured, harvested, and injected into full-depth surgical incisions in the dorsal area of mouse skin, which had been previously locally irradiated by 18 Gy X rays. As a control, cells irradiated with a dose of 20 Gy were also injected. The effect of radiation and fibroblast implants on the gain of skin wound strength was assayed. In an additional experiment freshly isolated cells were implanted. Two weeks following wounding the irradiated skin had reached only about a third of the strength of unirradiated skin. A significant increase of wound strength in irradiated skin was observed when 1.5-2 x 10(6) cultured fibroblasts or freshly isolated fibroblasts were injected into the 20-mm-long wound bed. Irradiated cells had significantly less effect. This suggests that implanting isolated syngeneic cells may "rescue" wounds from the effect of prior irradiation. Semiquantitative immunohistology of types I and III collagen was performed in parallel using a video image digitizing system. Levels of both types I and III collagen were altered in the dermis and the wound tissues in irradiated skin, but the implant of cultured fibroblasts did not affect notably the total levels and the disposition of the two collagen isotypes.     

The observation of partial regeneration of the tip of tail in newborn rat pups in a liquid medium

When the wound surface formed as a result of amputation of the tail tip in newborn rats was placed in sterile 0.9% aqueous solution of sodium chloride until full epithelialization of the defect, the epithelium moved onto the blood clot covering the wound. The blood clot was then substituted for connective tissue, into which the traumatized vertebra protruded. The vertebra restored its anatomical integrity, and this led to partial regrowth of the tail. A skin regenerate was formed on the apical tail surface with characteristic features of the intact skin of this locality. In the control animals, no regeneration of the vertebra epiphysis took place and a scar was formed at the stump end.     

The integrin αv-TGFβ signaling axis is necessary for epidermal proliferation during cutaneous wound healing

Proliferation and migration of epidermal keratinocytes are essential for proper cutaneous wound closure after injury. αv integrins and several of their ligands—vitronectin, TGFβ and thrombospondin—are up-regulated in healing wounds. However, the role of αv integrins in wound re-epithelialization is unknown. Here, we show that genetic depletion or antibody-mediated blockade of pan-integrin αv, or the specific heterodimer αvβ6, in keratinocytes limited epidermal proliferation at the wound edge and prevented re-epithelialization of wounded human organotypic skin both in vivo and in vitro. While we did not observe a migration defect upon αv blockade in vivo, αv was necessary for keratinocyte migration over longer distances in organotypic skin. Integrin αv is required for local activation of latent TGFβ, and the wound healing defect in the setting of integrin αv loss was rescued by exogenous, active TGFβ, indicating that the αv-TGFβ signaling axis is a critical component of the normal epidermal wound healing program. As chronic wounds are associated with decreased TGFβ signaling, restoration of TGFβ activity may have therapeutic utility in some clinical settings.     

Involvement of Matrin 3 and SFPQ/NONO in the DNA damage response

The DNA damage response (DDR) is a complex signaling network that is induced by DNA lesions and vigorously activated by double strand breaks (DSBs). The DSB response is mobilized by the nuclear protein kinase ATM, which phosphorylates key players in its various branches. SFPQ (PSF) and NONO (p54) are nuclear proteins that interact with each other and have diverse roles in nucleic acids metabolism. The SFPQ/NONO heterodimer was previously found to enhance DNA strand break rejoining in vitro. Our attention was drawn to these two proteins as they interact with the nuclear matrix protein Matrin 3 (MATR3), which we found to be a novel ATM target. We asked whether SFPQ and NONO too are involved in the DSB response. Proteins that function at the early phase of this response are often recruited to the damaged sites. We observed rapid recruitment of SFPQ/NONO to sites of DNA damage induced by laser microbeam. In MATR3 knockdown cells SFPQ/NONO retention at DNA damage sites was prolonged. SFPQ and MATR3 depletion led to abnormal accumulation of cells at the S-phase of the cell cycle following treatment with the radiomimetic chemical neocarzinostatin. Notably, proteins involved in DSB repair via nonhomologous end-joining co-immunoprecipitated with NONO; SFPQ depletion delayed DSB repair. Collectively the data suggest that SFPQ, NONO and MATR3 are involved in the early stage of the DSB response, setting the scene for DSB repair.     

Microencapsulated VEGF gene–modified umbilical cord mesenchymal stromal cells promote the vascularization of tissue-engineered dermis: an experimental study

Background aimsTissue-engineered dermis (TED) is thought to be the best treatment for skin defect wounds; however, lack of vascular structures in these products can cause slow vascularization or even transplant failure. We assessed the therapeutic potential of microencapsulated human umbilical cord mesenchymal stromal cells (hUCMSCs) expressing vascular endothelial growth factor (VEGF) in vascularization of TED.MethodshUCMSCs were isolated by means of enzymatic digestion and identified by means of testing biological characteristics. hUCMSCs were induced to differentiate into dermal fibroblasts in conditioned induction media. Collagen-chitosan laser drilling acellular dermal matrix (ADM) composite scaffold was prepared by means of the freeze dehydration and dehydrothermal cross-linking method. hUCMSC-derived fibroblasts were implanted on composite scaffolds to construct TED. TED with microencapsulated VEGF gene–modified hUCMSCs was then transplanted into skin defect wounds in pigs. The angiogenesis of TED at 1 week and status of wound healing at 3 weeks were observed.ResultsThe collagen-chitosan laser ADM composite has a uniform microporous structure. This composite has been used to grow hUCMSC-derived fibroblasts in vitro and to successfully construct stem cell–derived TED. Microencapsulated VEGF gene–modified hUCMSCs were prepared with the use of a sodium alginate–barium chloride one-step encapsulation technology. Seven days after the transplantation of the stem cell–derived TED and microencapsulated VEGF gene–modified hUCMSCs into the skin defect wounds on the backs of miniature pigs, the VEGF expression increased and the TED had a higher degree of vascularization. Re-epithelialization of the wound was completed after 3 weeks.ConclusionsMicroencapsulated VEGF gene–modified hUCMSCs can effectively improve the vascularization of TED and consequently the quality of wound healing.