S100A8, S100A9 and the S100A8/A9 heterodimer complex specifically bind to human endothelial cells: identification and characterization of ligands for the myeloid-related proteins S100A9 and S100A8/A9 on human dermal microvascular endothelial cell line-1 cells

The natural ligands of the S100 EF hand proteins S100A8 and A9 [myeloid-related proteins 8 and 14] have long been searched for in order to further the understanding of the role of the S100A8/A9-expressing monocyte subpopulation in progressing inflammatory processes. We demonstrate that S100A8, S100A9 and the S100A8/A9 heterodimeric complex bind to human dermal microvascular endothelial cell line (HMEC)-1 with an increasing binding capacity progressing from S100A8 < or = S100A9 < or = S100A8/A9. Similar results were obtained in the apolipoprotein E knockout mouse model, where preferably recombinant S100A9 but no S100A8 bound to the endothelium of the aorta ascendens. The binding of the S100A8/A9 heterodimer complex to activated HMEC-1 is specific as demonstrated by a dose-responding and satiable binding curve and the competition of FITC-labeled versus unlabeled protein. The protein character of the binding site was proven by treatment with trypsin. S100A8/A9 binding to HMEC-1 is inducible by lipopolysaccharide and tumor necrosis factor-alpha, and in the presence of calcium. A 163-kDa protein was isolated from a cell lysate of activated HMEC-1 cells using an affinity-chromatography protocol. The endothelial cell-associated ligand proteins isolated by the use of the S100A9 monomer and the S100A8/A9 dimer were subjected to mass spectrometry for protein identification. Clearly, alpha(2)-macroglobulin was identified as a binding partner for the S100A9 monomer, whereas no protein could be identified from the database for the ligand of the S100A8/A9 dimer.

Cooperation of C1q receptors and integrins in C1q-mediated endothelial cell adhesion and spreading

The interaction of C1q with endothelial cells elicits a multiplicity of biologic responses. Although these responses are presumed to be mediated by the interaction of C1q with endothelial cell surface proteins, the identity of the participants is not known. In this study we examined the roles of two C1q binding proteins, cC1q-R/calreticulin and gC1q-R/p33, in C1q-mediated adhesion and spreading of human dermal microvascular endothelial cells (HDMVEC). When HDMVEC were cultured in microtiter plate wells coated with concentrations of C1q ranging from 0 to 50 microg/ml, a specific and dose-dependent adhesion and spreading was observed. The extent of adhesion and spreading was similar to the adhesion seen on collagen-coated wells. Spreading (68 +/- 12%) and to a moderate extent adhesion (47 +/- 9%) were inhibited by anti-gC1q-R mAb 60.11. Similar effects were noted with polyclonal anti-cC1q-R but not with control nonimmune IgG. The two Abs had a slight additive effect (75 +/- 13% inhibition) when mixed together in the proportion of 100 microg/ml anti-gC1q-R and 30 microg/ml anti-cC1q-R. More importantly, a 100% inhibition of spreading, but not adhesion, to C1q-coated wells was observed when HDMVEC were cultured in the presence of 30 microM of the peptide GRRGDSP but not GRRGESP. Furthermore, while anti-beta(1) integrin Ab blocked both adhesion and spreading, anti-alpha(5) integrin blocked only spreading and not adhesion. Ag capture ELISA of endothelial cell membrane proteins using polyclonal anti-gC1q-R showed the presence of not only beta(1) and alpha(5) integrins but also CD44. Taken together these results suggest that endothelial cell adhesion and spreading require the cooperation of both C1qRs and beta(1) integrins and possibly other membrane-spanning molecules.

Vascular endothelial cells express isoforms of protein kinase A inhibitor

The expression and function of the endogenous inhibitor of cAMP-dependent protein kinase (PKI) in endothelial cells are unknown. In this study, overexpression of rabbit muscle PKI gene into endothelial cells inhibited the cAMP-mediated increase and exacerbated thrombin-induced decrease in endothelial barrier function. We investigated PKI expression in human pulmonary artery (HPAECs), foreskin microvessel (HMECs), and brain microvessel endothelial cells (HBMECs). RT-PCR using specific primers for human PKI alpha, human PKI gamma, and mouse PKI beta sequences detected PKI alpha and PKI gamma mRNA in all three cell types. Sequencing and BLAST analysis indicated that forward and reverse DNA strands for PKI alpha and PKI gamma were of >96% identity with database sequences. RNase protection assays showed protection of the 542 nucleotides in HBMEC and HPAEC PKI alpha mRNA and 240 nucleotides in HBMEC, HPAEC, and HMEC PKI gamma mRNA. Western blot analysis indicated that PKI gamma protein was detected in all three cell types, whereas PKI alpha was found in HBMECs. In summary, endothelial cells from three different vascular beds express PKI alpha and PKI gamma, which may be physiologically important in endothelial barrier function.

[Effect of subcutaneous tissue trimming on the survival skin area of avulsion skin flap]

OBJECTIVE

To investigate the effect of subcutaneous tissue trimming on the survival skin area of avulsion skin flap.

METHODS

Degloving injury was created in bilateral hind limbs of 7 pigs with avulsion injury machine, 4 cm x 10 cm avulsion skin flaps were elevated in degloving areas. Skin flaps in one side were replanted as control without any treatment. Subcutaneous tissue in the skin flaps of another side was partially excised and replanted by trimmed skin flaps. Survival skin flaps was calculated with computer at 7 days after operation.

RESULTS

In the control group, the survival skin area was (40.41 +/- 9.23)%, while in the experimental group, the survival skin area was (60.90 +/- 15.26)%. There was significant difference between the two groups (P < 0.05).

CONCLUSION

Trimming off subcutaneous tissue does improve the survival area of avulsion skin flap.

Isolation and characterization of dermal lymphatic and blood endothelial cells reveal stable and functionally specialized cell lineages

A plexus of lymphatic vessels guides interstitial fluid, passenger leukocytes, and tumor cells toward regional lymph nodes. Microvascular endothelial cells (ECs) of lymph channels (LECs) are difficult to distinguish from those of blood vessels (BECs) because both express a similar set of markers, such as CD31, CD34, podocalyxin, von Willebrand factor (vWF), etc. Analysis of the specific properties of LECs was hampered so far by lack of tools to isolate LECs. Recently, the 38-kD mucoprotein podoplanin was found to be expressed by microvascular LECs but not BECs in vivo. Here we isolated for the first time podoplanin(+) LECs and podoplanin(-) BECs from dermal cell suspensions by multicolor flow cytometry. Both EC types were propagated and stably expressed VE-cadherin, CD31, and vWF. Molecules selectively displayed by LECs in vivo, i.e., podoplanin, the hyaluronate receptor LYVE-1, and the vascular endothelial cell growth factor (VEGF)-C receptor, fms-like tyrosine kinase 4 (Flt-4)/VEGFR-3, were strongly expressed by expanded LECs, but not BECs. Conversely, BECs but not LECs expressed VEGF-C. LECs as well as BECs formed junctional contacts with similar molecular composition and ultrastructural features. Nevertheless, the two EC types assembled in vitro in vascular tubes in a strictly homotypic fashion. This EC specialization extends to the secretion of biologically relevant chemotactic factors: LECs, but not BECs, constitutively secrete the CC chemokine receptor (CCR)7 ligand secondary lymphoid tissue chemokine (SLC)/CCL21 at their basal side, while both subsets, upon activation, release macrophage inflammatory protein (MIP)-3alpha/CCL20 apically. These results demonstrate that LECs and BECs constitute stable and specialized EC lineages equipped with the potential to navigate leukocytes and, perhaps also, tumor cells into and out of the tissues.

[Bioactivity and test grafting of acellular dermal matrix containing fibroblasts]

OBJECTIVE

To investigate the bioactivity of acellular dermal matrix with fibroblasts and its role as dermal skeleton.

METHODS

Human fibroblasts (HFs) were planted onto the surface of acellular dermal matrix (ADM) to form living dermal substitute. The IL -- 6, IL -- 8 and TGF contents in the supernatant of the culture of HF -- ADM were determined with ELISA method, and the secretion of hyaluronic acid and laminin from extracellular matrix was measured with RIA method. The speed of vascularization and the wound contracture rate were observed after the dermal substitute was grafted on the full skin loss wound of Balb/c-nu mice (nude mice).

RESULTS

HFs grew very well after being planted onto ADM so as to form a single layer of cellular membrane. Many kinds of cytokines and extra cellular matrix components were secreted. Compared with simple acellular dermal grafting, the vascularization was accelerated, and the wound contracture rate decreased, after the living dermal substitute being grafted on the wound.

CONCLUSION

The ADM seeded with HFs exhibited excellent bioactivity and might be an optimal dermal substitute.

Mixture component effects on the in vitro dermal absorption of pentachlorophenol

Interactions between chemicals in a mixture and interactions of mixture components with the skin can significantly alter the rate and extent of percutaneous absorption, as well as the cutaneous disposition of a topically applied chemical. The predictive ability of dermal absorption models, and consequently the dermal risk assessment process, would be greatly improved by the elucidation and characterization of these interactions. Pentachlorophenol (PCP), a compound known to penetrate the skin readily, was used as a marker compound to examine mixture component effects using in vitro porcine skin models. PCP was administered in ethanol or in a 40% ethanol/60% water mixture or a 40% ethanol/60% water mixture containing either the rubefacient methyl nicotinate (MNA) or the surfactant sodium lauryl sulfate (SLS), or both MNA and SLS. Experiments were also conducted with 14C-labelled 3,3',4,4'-tetrachlorobiphenyl (TCB) and 3,3',4,4',5-pentachlorobiphenyl (PCB). Maximal PCP absorption was 14.12% of the applied dose from the mixture containing SLS, MNA, ethanol and water. However, when PCP was administered in ethanol only, absorption was only 1.12% of the applied dose. There were also qualitative differences among the absorption profiles for the different PCP mixtures. In contrast with the PCP results, absorption of TCB or PCB was negligible in perfused porcine skin, with only 0.14% of the applied TCB dose and 0.05% of the applied PCB dose being maximally absorbed. The low absorption levels for the PCB congeners precluded the identification of mixture component effects. These results suggest that dermal absorption estimates from a single chemical exposure may not reflect absorption seen after exposure as a chemical mixture and that absorption of both TCB and PCB are minimal in this model system.

[Reconstruction of digital avulsion with pre-fabricated subdermal vascular network skin flap by ultrasonic liposuction]

OBJECTIVE

To investigate the clinical application of subdermal vascular network skin flap pre-fabricated by ultrasonic liposuction in reconstruction of digital avulsion.

METHODS

Forty-seven injured fingers of 23 cases were treated from June 1997 to February 2000. Conventional abdominal skin flap was elevated, according to the size of digital avulsion, and subcutaneous fat was removed with scissors. Ultrasonic liposuction technology was adopted, in order to minimize the injury of subdermal vascular vessels, to remove the fat particles close to the vascular network. Finally, the pre-fabricated skin flap was used to repair the digital avulsion. The vascular pedicle was severed in 5 to 7 days after operation. The range of skin flap was 4 cm x 3 cm to 8 cm x 7 cm, and the ratio of length and width was (2 to 3) to 1.

RESULTS

All the skin flaps were survived. Twenty-one patients were available for postoperative follow-up for 6 to 24 months. The motion of interphalangeal joint achieved functional recovery, and the sensation of pain, temperature and taction recovered well.

CONCLUSION

Ultrasonic liposuction does not obviously injure the subdermal vascular network skin flap, it is a simple and safe method for treatment of digital avulsion.

Appearance of peculiar vessels with immunohistological features of high endothelial venules in the dermis of moxibustion-stimulated rat skin

Morphological changes of the dermal blood vessels ofmoxibustion-stimulated rat skin were examined with reference to the lymphocyte migration. After long-term stimulation with direct moxibustion to the acupoint tsu-san-li (St-36), peculiar vessels that possess immunohistological features of high endothelial venules could be observed in the moxa-stimulated acupoint dermis. Endothelial cells of the vessels had well-developed Golgi apparatus in their plump cytoplasms, and they strongly expressed intercellular adhesion molecule-1 on the luminal surface. These data suggest that the appearance of the peculiar vessels in the dermis acts toward the active infiltration of blood-lymphocytes into the acupoint skin.

Human dermal pericytes express 3G5 ganglioside--a new approach for microvessel histology in the skin

BACKGROUND

Pericytes cover the abluminal surface of microvessels and play an important role in capillary regulation and pathology. Studies on pericytes have been hindered by the lack of specific markers with which to facilitate microscopic identification of this cell type. Expression of the cell surface 3G5 ganglioside antigen has been reported in cultured retinal and cardiac pericytes. The objective of this study was to determine the usefulness of monoclonal antibody 3G5 as a pericyte marker in human skin.

METHODS

Cryosections of 21 skin biopsies were examined by direct fluorescence technique with anti-3G5, anti-von Willebrand factor, anti-alpha-smooth muscle actin or DNA fluorochrome.

RESULTS

In human dermis, 3G5 expression is limited to pericytes discriminating this cell type from all other cells including smooth muscle cells, myofibroblasts and myoepithelial cells. We found a pericyte: endothelial cell ratio of 1:12.4 (+/-7.1), and a difference of alpha-smooth muscle actin expression between the subpapillary plexus and the microvessels of the Stratum reticulare.

CONCLUSIONS

3G5 mAB is an excellent and so far the only reported tool for identification of dermal pericytes by fluorescent light microscopy. Moreover, this is the first report of the application of 3G5 technique to the microvasculature in tissue sections at the light microscopic level.

Burn depth and its histological measurement

This paper describes a new technique for burn depth measurement, based on the histological assessment of dermal microvascular occlusion in burn biopsies. The technique was validated in a preliminary study of acute progressive microvascular damage in five adults with partial thickness burns. Burn depth was calculated at three time points post burn from the mean histological measurement of the most superficial patent and the deepest blocked vessels in five separate sections from each biopsy. The results were expressed as a percentage of the total dermal thickness and correlated well with the laser Doppler measurement of dermal blood flow and clinical estimation of burn depth. The reproducibility of the technique was tested by the repeated blind analysis of five randomly chosen biopsies on a separate occasion. Altman-Bland plot analysis demonstrated a median variation of 0.1% (95% confidence interval -1 to 2%). A second independent observer (MPHT), who carried out a blind analysis of the same randomly chosen biopsies, tested the precision of the technique. The median variation was 2% (95% confidence interval -5 to 8.5%).

Quantitative histopathologic findings of erythromelanosis follicularis faciei et colli

BACKGROUND

Even though only 33 cases of Erythromelanosis follicularis faciei et colli (EFFC) have been reported around the world, there have been no quantitative clinicopathological studies yet. The purpose of this study is to examine quantitatively clinical and histopathological evaluations of EFFC using image analysis system.

METHOD

Clinical grading of its severity was assessed. Many parameters of the horny layer, granular layer, epidermis and the dermal components were measured and compared to controls by image analysis. The correlation between the histological findings and clinical grading was assessed.

RESULT

Thickness and compactness of the horny layer was significantly increased in EFFC. There were no significant differences in the number of melanocytes and severity of pigmentation between EFFC and controls; however, melanization was slightly increased in EFFC. The percent area of the superficial blood vessels was significantly increased and correlated with visual grading of erythema. Diameters of hair shafts and outer root sheaths, and thickness of inner root sheaths were decreased. Basal layer pigmentation was correlated with the clinical features of pigmentation.

CONCLUSION

This study supported the findings of hyperkeratosis and dilatation of superficial dermal blood vessels in EFFC. The pigmentation of the basal layer and the percent area of the inner spaces of the superficial dermal blood vessels may reflect the clinical severity more than the other parameters. Although follicular plugging is a characteristic clinical feature of EFFC, enlargement of hair follicles and hair shafts were not characteristic pathologic changes EFFC in our study.

Telomerized human microvasculature is functional in vivo

Previously we showed the superior in vitro survival of human telomerase reverse transcriptase (hTERT)-transduced human endothelial cells (EC). Here we show that retroviral-mediated transduction of hTERT in human dermal microvascular EC (HDMEC) results in cell lines that form microvascular structures when subcutaneously implanted in severe combined immunodeficiency (SCID) mice. Anti-human type IV collagen basement membrane immunoreactivity and visualization of enhanced green fluorescent protein (eGFP)-labeled microvessels confirmed the human origin of these capillaries. No human vasculature was observed after implantation of HT1080 fibrosarcoma cells, 293 human embryonic kidney cells, or human skin fibroblasts. Intravascular red fluorescent microspheres injected into host circulation were found within green "telomerized" microvessels, indicating functional murine-human vessel anastamoses. Whereas primary HDMEC-derived vessel density decreased with time, telomerized HDMEC maintained durable vessels six weeks after xenografting. Modulation of implant vessel density by exposure to different angiogenic and angiostatic factors demonstrated the utility of this system for the study of human microvascular remodeling in vivo.

Expression of chemokine genes in human dermal microvascular endothelial cell lines infected with Orientia tsutsugamushi

Scrub typhus, caused by Orientia tsutsugamushi, is characterized by local as well as systemic inflammatory manifestations. The main pathologic change is focal or disseminated multiorgan vasculitis, which is caused by the destruction of endothelial cells and perivascular infiltration of leukocytes. We investigated the regulation of chemokine induction in transformed human dermal microvascular endothelial cells (HMEC-1) in response to O. tsutsugamushi infection. The monocyte chemoattractant protein-1 (MCP-1) and interleukin 8 (IL-8) mRNAs were induced, and their levels showed a transitory peak at 3 and 6 h, respectively. The RANTES transcript was detected at 6 h after infection, with increased levels evident by 48 h. The induction of the MCP-1 and IL-8 genes was not blocked by cycloheximide, suggesting that de novo protein synthesis of host cell proteins is not required for their transcriptional activation. Heat- or UV-inactivated O. tsutsugamushi induced a similar extent of MCP-1 and IL-8 responses. The induction of MCP-1 and IL-8 transcripts in the endothelial cells by O. tsutsugamushi was not blocked by the inhibitors of NF-kappaB. Furthermore, the activation of NF-kappaB was not detected in HMEC-1 stimulated with O. tsutsugamushi. These results demonstrate that heat-stable molecules of O. tsutsugamushi induce the MCP-1 and IL-8 genes and the induction of the chemokine genes may be mediated by an NF-kappaB independent mechanism. We also showed that another major transcription factor, activator protein-1 (AP-1), was up-regulated in HMEC-1 after O. tsutsugamushi infection. This suggests the possible involvement of AP-1 in the chemokine gene expression.

Mitochondria-rich cells in gills and skin of an African lungfish, Protopterus annectens

We used scanning electron microscopy, the vital dye DASPEI and an antibody to the inner mitochondrial membrane to study the presence and localisation of mitochondria-rich cells in the gills and skin (opercular, dorsal and ventral) of the lungfish Protopterus annectens in its free-swimming conditions and at the beginning of aestivation. In the free-swimming period, the gills were short and thick and the pavement cells were extremely large (30-40 microns). The mitochondria-rich cells, which were distributed in the secondary and primary epithelium, occurred as two morphologically different types, i.e. elongated and oval, similar to the alpha and beta chloride cells of fresh water teleosts. In the skin, only one type of mitochondria-rich cells was found, resembling the alpha chloride cells. All the mitochondria-rich cells distributed in the gills and skin were labelled with anti Ca(2+)-ATPase serum indicating the possible uptake of Ca2+ at freshwater chloride cell level. At the start of aestivation, the skin and gills were covered by a thick layer of mucus and the epithelium of the gills was reduced. The mitochondria-rich cells were almost completely covered by the pavement cells.

Cutaneous blood vessels in scent pigs

The purpose of this study was to systematically provide anatomic data for flap research in plastic surgery on the cutaneous blood vessels. Seven scent pigs used in this study were killed anesthetically, and their carotid vessels were intubated and injected with a black liquid rubber. Twenty-four hours later, the integument of the scent pig was removed, and the perforating points of the cutaneous vessels were recorded. The different-sized pieces of integument became transparent. Part of this transparent skin tissue was cut into cross-sectional strips. There were three types of the cutaneous vascular source, the same as in humans. Six division levels of vessels in the skin were identified, which formed five vascular plexuses and two systems (the perforating vessel system and the cutaneous vessel system). There were two sets of vein systems: the concomitant vein and the oscillating vein; the latter can be divided into regular and irregular types. The structures of the perforating vessel system and the cutaneous vessel system were the morphological basis for choosing flaps. Two anatomic points have been emphasized: the preserved vascular plexus in thin flaps (not the subcutaneous vascular network reported previously) and the dependency of vascular structure on its location. Otherwise, this study has also provided two new kinds of flaps used in experimental study: the arterial loop flap and the intermuscular septal perforator flap. Although there were differences as well as similarities in skin vasculature between humans and the scent pig, the scent pig is still suitable for flap research.

Regulation of endothelial CD73 by adenosine: paracrine pathway for enhanced endothelial barrier function

During episodes of inflammation, multiple cell types release adenine nucleotides in the form of ATP, ADP, 5'-AMP, and adenosine. In particular, following activation, polymorphonuclear leukocytes release larger quantities of 5'-AMP. Extracellular 5'-AMP is metabolized to adenosine by surface-expressed 5'-ectonucleotidase (CD73). Adenosine liberated by this process activates surface adenosine A(2B) receptors, results in endothelial junctional reorganization, and promotes barrier function. We hypothesized that adenosine signaling to endothelia provides a paracrine loop for regulated expression of CD73 and enhanced endothelial barrier function. Using an in vitro microvascular endothelial model, we investigated the influence of 5'-AMP; adenosine; and adenosine analogues on CD73 transcription, surface expression, and function. Initial experiments revealed that adenosine and adenosine analogues induce CD73 mRNA (RT-PCR), surface expression (immunoprecipitation of surface biotinylated CD73), and function (HPLC analysis of etheno-AMP conversion to ethenoadenosine) in a time- and concentration-dependent fashion. Subsequent studies revealed that similar exposure conditions increase surface protein through transcriptional induction of CD73. Analysis of DNA-binding activity by EMSA identified a functional role for CD73 cAMP response element and, moreover, indicated that multiple cAMP agonists induce transcriptional activation of functional CD73. Induced CD73 functioned to enhance 5'-AMP-mediated promotion of endothelial barrier (measured as a paracellular flux of 70-kDa FITC-labeled tracer). These results provide an example of transcriptional induction of enzyme (CD73) by enzymatic product (adenosine) and define a paracrine pathway for the regulated expression of vascular endothelial CD73 and barrier function.

The dermis

All the dermal structures are less well developed in the newborn than in the older infant or child, but there are few important consequences of this. Sweating in response to a thermal stimulus occurs at birth in the term infant and can be detected in most preterm infants from 2 weeks of age. It is poorly developed though. Emotional (palmar/plantar) sweating is present from birth in term infants only. Skin blood flow can be regulated in term and preterm infants, and is often measured indirectly as a temperature gradient. Such a gradient is temperature as well as illness dependent which limits its use as a clinical tool. Sensory nerve endings are readily stimulated in the most immature infants. Finally, damage to the skin in the newborn period commonly leads to scarring, although this usually improves with time.

Expression of antisense to integrin subunit beta 3 inhibits microvascular endothelial cell capillary tube formation in fibrin

alpha(v)beta(3) antagonists are potent angiogenesis inhibitors, and several different classes of inhibitors have been developed, including monoclonal antibodies, synthetic peptides, and small organic molecules. However, each class of inhibitor works by the same principal, by blocking the binding of ligands to alpha(v)beta(3). In an effort to develop an alpha(v)beta(3) inhibitor that down-regulates the actual level of alpha(v)beta(3), we developed an antisense strategy to inhibit alpha(v)beta(3) expression in vitro. beta(3) antisense expressed in endothelial cells specifically down-regulated alpha(v)beta(3) and inhibited capillary tube formation, with the extent of down-regulation correlating with the extent of tube formation inhibition. This inhibition was matrix-specific, since tube formation was not inhibited in Matrigel. These findings support the notion that alpha(v)beta(3) is required for an essential step of angiogenesis in fibrin, namely capillary tube formation. These results suggest that pseudogenetic inhibition of beta(3) integrins using antisense techniques may ultimately provide a therapeutic means to inhibit angiogenesis in vivo.

Bioartificial skin

The loss of skin has been one of the oldest, yet most frequent and costly problems in our health care system. To restore functional and esthetic integrity in patients with unstable or hypertrophic scars, in burn patients and after skin loss for hereditary, traumatic or oncological reasons, an armamentarium of reconstructive surgical procedures including autogenous, allogenous and xenogenous tissue transfer as well as implantation of alloplastic materials has been favored. For several decades there has been increasing interest focused on 'tissue engineering' of dermal, epidermal and full thickness skin substitutes by both biological and synthetic matrices. At our institution (Hannover Medical School), a collagen/glycosaminoglycan dermal regeneration matrix has been used for immediate dermal coverage after escharectomy in burn injuries as well as for dermal replacement in chronically unstable scars. This article gives an overview on the current state of the art in bioartificial skin as well as our personal experience with the collagen/glycosaminoglycan matrix for dermal replacement in different clinical situations.

Pericapillary fibrin deposits and skin hypoxia precede the changes of lipodermatosclerosis in limbs at increased risk of developing a venous ulcer

This study investigated the possibility that pericapillary fibrin deposition, found in the calf skin of patients with venous ulceration and lipodermatosclerosis, might already be present in the dermis of the gaiter area of apparently healthy limbs before any skin changes were visible. The apparently healthy limbs of 19 consecutive patients with a healed venous ulcer on one leg and no history of ulceration or clinical evidence of lipodermatosclerosis in the opposite calf, were studied. Bipedal ascending phlebography and foot volume plethysmography were performed, and systemic fibrinolytic activity and fibrinogen levels were calculated. Transcutaneous oxygen measurements were expressed as a ratio of levels from a fixed position in the gaiter skin over a control site on the arm. Biopsies of a standard site in the gaiter skin and the thigh were assessed for the presence of laminin, fibrinogen and fibronectin using immunofluorescent microscopy. The extent of pericapillary fluorescence was expressed as a ratio of the number of capillaries with deposits divided by the total number of capillaries staining with laminin (fibrin and fibronectin scores). Pericapillary fibrin deposits were observed in the dermis in 16 of the biopsies of the gaiter region (median score 0.20), and in eight of the biopsies from the thigh (median score 0.0). This difference was highly significant (P<0.01, Wilcoxon signed rank test). The transcutaneous oxygen ratio correlated negatively with the fibrin score (Spearman rank correlation coefficient -0.62, P<0.01), and there was a weak negative correlation between the half volume refilling time on foot volume plethysmography (an indicator of venous reflux) and the fibrin score (Speraman rank correlation coefficient -0.47, P<0.05). No such correlation could be shown between the fibrin score and the indicators of calf pump function, the euglobulin clot lysis time or the plasma fibrinogen. The presence of significant numbers of pericapillary fibrin deposits within the dermis of the gaiter skin has been demonstrated in 84% of this cohort of 'at risk' limbs before there is any evidence of clinical lipodermatosclerosis.

Increased expression of insulin-like growth factor I in skin in amyotrophic lateral sclerosis

OBJECTIVES

Insulin-like growth factor I (IGF-I) has potent effects on motor neuron survival and is being studied as a possible therapeutic agent for ALS. However, little is known concerning IGF-I in the skin of patients with amyotrophic lateral sclerosis (ALS). The aim was to evaluate IGF-I immunoreactivity of skin in patients with ALS.

METHODS

IGF-I immunoreactivity of skin from 18 patients with ALS and 16 controls was examined.

RESULTS

IGF-I immunoreactivity was markedly positive in the epidermis and dermal blood vessels and glands and was moderately positive in the reticular dermis in all patients with ALS. On the other hand, the epidermis and dermal blood vessels and glands and the reticular dermis showed a weak IGF-I immunoreactivity in controls. The optical density for IGF-I immunoreactivity of the epidermis and dermal blood vessels and glands, and the reticular dermis in patients with ALS was significantly higher than in diseased controls, and was significantly increased with duration of illness.

CONCLUSIONS

These data suggest that a metabolic alteration of IGF-I may take place in the skin of patients with ALS.