Matrix metalloproteinase activity and immunohistochemical profile of matrix metalloproteinase-2 and -9 and tissue inhibitor of metalloproteinase-1 during human dermal wound healing

CCL2 promotes proliferation, migration and angiogenesis through the MAPK/ERK1/2/MMP9, PI3K/AKT, Wnt/β‑catenin signaling pathways in HUVECs

Severe bone trauma can lead to poor or delayed bone healing and nonunion. Bone regeneration is based on the interaction between osteogenesis and angiogenesis. Angiogenesis serves a unique role in the repair and remodeling of bone defects. Monocyte chemoattractant protein-1, also known as CC motif ligand 2 (CCL2), is a member of the CC motif chemokine family and was the first human chemokine to be revealed to be an effective chemokine of monocytes. However, its underlying mechanism in angiogenesis of bone defect repair remains to be elucidated. Therefore, the present study investigated the detailed mechanism by which CCL2 promoted angiogenesis in bone defects based on cell and animal model experiments. In the present study, CCL2 promoted proliferation, migration and tube formation in human umbilical vein endothelial cells (HUVECs) in a concentration-dependent manner. Western blot analysis revealed that treatment of HUVECs with CCL2 upregulated the protein expression levels of rho-associated coiled-coil-containing protein kinase (Rock)1, Rock2, N-cadherin, c-Myc and VEGFR2. Furthermore, CCL2 promoted the expression of MAPK/ERK1/2/MMP9, PI3K/AKT and Wnt/β-catenin signaling pathway-related proteins, which also demonstrated that CCL2 promoted these functions in HUVECs. Immunohistochemical staining of Sprague Dawley rat femurs following bone defects revealed that VEGF expression was positive in the newly formed bone area in each group, while the expression area of VEGF in the CCL2 addition group was markedly increased. Therefore, CCL2 is a potential therapeutic approach for bone defect repair and reconstruction through the mechanism of angiogenesis-osteogenesis coupling.

Biomarkers of Skin Graft Healing in Venous Leg Ulcers

There is a need for biomarkers that predict the success of transplantation of venous leg ulcers (with autologous split-thickness skin grafts). The primary objective of this exploratory study was to investigate the association between split-thickness skin graft healing in venous leg ulcers and candidate wound fluid biomarkers representing inflammatory cell and endogenous proteinase activities, and bioactivity. A secondary objective was to compare biomarker levels of the 17 venous leg ulcers with sterile split-thickness skin graft donor-site wounds in another 10 patients with venous leg ulcers. Wound fluids were collected for 24 h using a validated method. The concentration of pre-operative matrix metalloproteinase-9 in wound fluid was higher in venous leg ulcers showing good healing (n = 10) than in venous leg ulcers showing poor healing (n = 7) 12 weeks after transplantation with meshed split-thickness skin grafts. The diagnostic value of matrix metalloproteinase-9 was good according to receiver-operating characteristic curve analysis. Matrix metalloproteinase activity in wound fluids from split-thickness skin graft donor-site wounds increased as a function of time and healing, but was still lower than matrix metalloproteinase activity in venous leg ulcer wound fluids, which showed increased levels of most biomarkers except for matrix metalloproteinase-9 and matrix metalloproteinase-2. In conclusion, wound fluid matrix metalloproteinase-9 concentration is a potential predictive biomarker of split-thickness skin graft healing in venous leg ulcers.

Hard-to-heal wound treated with Integra Flowable Wound Matrix: analysis and clinical observations

Skin healing defects severely impair the quality of life of millions of people and burden healthcare systems globally. The therapeutic approach to these pathologies still represents a challenge. Novel scaffolds, used as dermal substitutes, possibly represent a promising strategy in complex wound management. Integra Flowable Wound Matrix (IFWM) is composed of a lyophilised, micronised form of collagen/chondroitin sulphate matrix, already used in regenerative medicine and endorsed in the therapy of diabetic foot lesions. In this paper, IFWM was applied to a tunnelling hard-to-heal skin lesion in order to restore tissue integrity. Although the different phases of skin wound healing are well established, the molecular mechanism underpinning IFWM-induced tissue repair are almost unknown. Here, we report, for the first time, the comparative analysis of molecular, histological and clinical observations of the healing process of a hard-to-heal tunnelling skin wound. The therapeutic success of this clinical case allowed us to recommend the use of IFWM as a tissue substitute in this rare type of hard-to-heal wound in which the high inflammatory status hampered the natural healing process.

Keratin-Alginate Sponges Support Healing of Partial-Thickness Burns

Deep partial-thickness burns damage most of the dermis and can cause severe pain, scarring, and mortality if left untreated. This study serves to evaluate the effectiveness of crosslinked keratin–alginate composite sponges as dermal substitutes for deep partial-thickness burns. Crosslinked keratin–alginate sponges were tested for the ability to support human dermal fibroblasts in vitro and to support the closure and healing of partial-thickness burn wounds in Sus scrofa pigs. Keratin–alginate composite sponges supported the enhanced proliferation of human dermal fibroblasts compared to alginate-only sponges and exhibited decreased contraction in vitro when compared to keratin only sponges. As dermal substitutes in vivo, the sponges supported the expression of keratin 14, alpha-smooth muscle actin, and collagen IV within wound sites, comparable to collagen sponges. Keratin–alginate composite sponges supported the regeneration of basement membranes in the wounds more than in collagen-treated wounds and non-grafted controls, suggesting the subsequent development of pathological scar tissues may be minimized. Results from this study indicate that crosslinked keratin–alginate sponges are suitable alternative dermal substitutes for clinical applications in wound healing and skin regeneration.

Complex challenges of estimating the age and vitality of muscle wounds: a study with matrix metalloproteinases and their inhibitors on animal and human tissue samples

The estimation of wound age and wound vitality is a recurring task in forensic routine work and has been subject of forensic research for a long time. By now, an unrestrictedly reliable marker or set of markers has not been found. In a study on myocardial infarctions, matrix metalloproteinases (MMP) 2 and 9 as well as tissue inhibitor of matrix metalloproteinases 1 (TIMP-1) were detected immunohistochemically in mechanically wounded myocardium (ECG electrodes, vessel ligations). Against this background, the potency of MMP-9, MMP-2, and TIMP-1 as markers for the estimation of wound age and wound vitality was tested in a broad approach with human tissue samples drawn during autopsies and with an animal model, the isolated perfused Langendorff heart. The study comprised samples of injured human skeletal muscle, injured human myocardium, rats’ hearts with vital wounds, and rats’ hearts with postmortem-inflicted wounds that were all stained immunohistochemically. The results showed great scattering, leading to the conclusion that MMP-2, MMP-9, and TIMP-1 are not suitable for wound age estimation. Merely the results for TIMP-1 suggested that this marker might be able to differentiate between vital and postmortem-inflicted wounds. With a view to the promising results of the preceding study, the results underline the necessity to test possible markers of wound age/wound vitality on a large and diverse sample set.

Responses of matrix metalloproteinases to hyperbaric oxygen treatment: changing for good or ill?

Background: Hyperbaric oxygen (HBO₂) is currently emerging as a promising therapeutic option for diseases involving impaired tissue repair and remodeling. In this regard, HBO₂ has been shown to modulate signaling pathways responsible for matrix metalloproteinases (MMPs) regulation, which makes the MMPs interesting targets for investigation. However, the understanding regarding how HBO₂ treatment affects the expression and activity of the MMP family members in different tissues and diseases needs to be clarified. The precise roles of MMPs in the physiopathology of various tissue repair disorders also remain unclear. Because of potential off-target systemic effects of the HBO₂ on MMPs, researchers and physicians should carefully consider whether their patients could be affected adversely by HBO₂ exposure. Aims: This narrative review provides an overview of MMP biology (structure, function, and regulation) and summarizes available data showing how MMPs respond to HBO₂ in different tissues and pathologies, also highlighting possible mechanisms.

Early Treatment Effects of Nonablative Fractional Lasers (NAFL) on Hypertrophic Scars in an Animal Model

BACKGROUND AND OBJECTIVES

Recently, there have been several attempts to apply the laser therapy to hypertrophic scars (HTS). In particular, the fractional laser is in the spotlight for its usefulness in rapid wound healing and dermal remodeling. However, most previous studies have focused on the ablative fractional laser (AFL), and there are no studies on the mechanism of the nonablative fractional laser (NAFL) effect in HTS treatment. In this study, we aimed to evaluate the changes in histology and molecular chemistry to provide scientific evidence for the early treatment of HTS with NAFL.

STUDY DESIGN/MATERIALS AND METHODS

A total of 40 hypertrophic burn scars were made on the abdomens of two female pigs. After epithelialization, the HTS were randomly subdivided into four groups-control, AFL, NAFL (low energy), and NAFL (high energy). Laser treatment was initiated 1 week after the crust fell and the epithelium became covered, and it was repeated for six sessions over an interval of 2 weeks. Five excisional biopsies were obtained for histologic analysis and biomarker assessment.

RESULTS

Histologically, dermal remodeling with thin coil-shaped collagen fibers was observed in the NAFL groups. It also showed a significant increase of matrix metalloproteinase-2 (MMP-2) and Decorin at 16 weeks in an enzyme-linked immunosorbent assay. The reverse-transcription polymerase chain reaction analysis showed a tendency that high-pulse energy of NAFL led to higher messenger RNA expression than did the low-energy group.

CONCLUSION

The NAFL-treated groups showed characteristic collagen re-arrangement and a significant increase in MMP-2 and Decorin. These molecular changes suggest that MMP-2 and Decorin play a significant role in dermal remodeling. Early NAFL treatment for HTS could be supported with both histological and molecular evidence. Lasers Surg. Med. © 2020 Wiley Periodicals, Inc.

A Comparative Study of Engineered Dermal Templates for Skin Wound Repair in a Mouse Model

Engineered dermal templates have revolutionised the repair and reconstruction of skin defects. Their interaction with the wound microenvironment and linked molecular mediators of wound repair is still not clear. This study investigated the wound bed and acellular "off the shelf" dermal template interaction in a mouse model. Full-thickness wounds in nude mice were grafted with allogenic skin, and either collagen-based or fully synthetic dermal templates. Changes in the wound bed showed significantly higher vascularisation and fibroblast infiltration in synthetic grafts when compared to collagen-based grafts (P ≤ 0.05). Greater tissue growth was associated with higher prostaglandin-endoperoxide synthase 2 (Ptgs2) RNA and cyclooxygenase-2 (COX-2) protein levels in fully synthetic grafts. Collagen-based grafts had higher levels of collagen III and matrix metallopeptidase 2. To compare the capacity to form a double layer skin substitute, both templates were seeded with human fibroblasts and keratinocytes (so-called human skin equivalent or HSE). Mice were grafted with HSEs to test permanent wound closure with no further treatment required. We found the synthetic dermal template to have a significantly greater capacity to support human epidermal cells. In conclusion, the synthetic template showed advantages over the collagen-based template in a short-term mouse model of wound repair.

Processed eggshell membrane powder regulates cellular functions and increase MMP-activity important in early wound healing processes

Avian eggshell membrane (ESM) is a natural biomaterial that has been used as an alternative natural bandage to cure wounds, and is available in large quantities from egg industries. We have previously demonstrated that processed eggshell membrane powder (PEP), aiming to be used in a low cost wound healing product, possesses anti-inflammatory properties. In this study, we further investigated effects of PEP on MMP activities in vitro (a dermal fibroblast cell culture system) and in vivo (a mouse skin wound healing model). Three days incubation with PEP in cell culture led to rearrangement of the actin-cytoskeleton and vinculin in focal adhesions and increased syndecan-4 shedding. In addition, we observed increased matrix metalloproteinase type 2 (MMP-2) enzyme activation, without effects on protein levels of MMP-2 or its regulators (membrane type 1 (MT1)-MMP and tissue inhibitor of matrix metalloproteinase type 2 (TIMP-2). Longer incubation (10 days) led to increased protein levels of MMP-2 and its regulators. We also observed an increased alpha-smooth muscle actin (α-SMA) production, suggesting an effect of PEP on myofibroblast differentiation. In vivo, using the mouse skin wound healing model, PEP treatment (3 days) increased MMP activity at the wound edges, along with increased MMP-2 and MMP-9 protein levels, and increased keratinocyte cell proliferation. Altogether, our data suggest PEP stimulates MMP activity, and with a positive effect on early cellular events during wound healing.

Exogenous peripheral blood mononuclear cells affect the healing process of deep‑degree burns

The regenerative repair of deep-degree (second degree) burned skin remains a notable challenge in the treatment of burn injury, despite improvements being made with regards to treatment modality and the emergence of novel therapies. Fetal skin constitutes an attractive target for investigating scarless healing of burned skin. To investigate the inflammatory response during scarless healing of burned fetal skin, the present study developed a nude mouse model, which was implanted with normal human fetal skin and burned fetal skin. Subsequently, human peripheral blood mononuclear cells (PBMCs) were used to treat the nude mouse model carrying the burned fetal skin. The expression levels of matrix metalloproteinase (MMP)-9 and tissue inhibitor of metalloproteinases (TIMP)-1 were investigated during this process. In the present study, fetal skin was subcutaneously implanted into the nude mice to establish the murine model. Hematoxylin and eosin staining was used to detect alterations in the skin during the development of fetal skin and during the healing process of deep-degree burned fetal skin. The expression levels of MMP-9 and TIMP-1 were determined using immunochemical staining, and their staining intensity was evaluated by mean optical density. The results demonstrated that fetal skin subcutaneously implanted into the dorsal skin flap of nude mice developed similarly to the normal growth process in the womb. In addition, the scarless healing process was clearly observed in the mice carrying the burned fetal skin. A total of 2 weeks was required to complete scarless healing. Following treatment with PBMCs, the burned fetal skin generated inflammatory factors and enhanced the inflammatory response, which consequently resulted in a reduction in the speed of healing and in the formation of scars. Therefore, exogenous PBMCs may alter the lowered immune response environment, which is required for scarless healing, resulting in scar formation. In conclusion, the present study indicated that the involvement of inflammatory cells is important during the healing process of deep-degree burned skin, and MMP-9 and TIMP-1 may serve important roles in the process of scar formation.

Effect of low-level laser therapy on angiogenesis and matrix metalloproteinase-2 immunoexpression in wound repair

Low-level laser therapy (LLLT) induces anti-inflammatory and angiogenic activities in wound healing. However, the mechanism of action and optimal parameters require further clarification. In this study, we investigated the effects of LLLT on wound healing matrix metalloproteinase (MMP)-2 immunoexpression and angiogenic processes. Twenty female Wistar rats were randomly divided into four groups (n = 5) according to the treatments as follows. CG7 and CG14 were control groups at days 7 and 14, respectively, which received physiological saline (0.9 % NaCl daily). LG7 and LG14 were laser therapy groups at days 7 and 14, respectively, which received two (LG7) or four (LG14) LLLT applications (40 mW; 660 nm; 4 J/cm²). A dorsal skin sample in the wound area (measuring 2 cm²) was removed after the experimental period, and then the animals were euthanized. The specimens were processed for qualitative and quantitative histological analyses and measurement of MMP-2 expression in the dermis and epidermis. A persistent crust and moderate number of inflammatory cells were found in CG7 and CG14 groups. In the LG14 group, wounds demonstrated complete re-epithelization at the remodeling phase. Angiogenesis and MMP-2 expression were higher in LLLT-treated groups, particularly the LG14 group, which correlated according to the Spearman correlation test. LLLT improves wound healing by enhancing neocollagenesis, increasing the amount of new vessels formed in the tissue (neoangiogenesis), and modulating MMP-2 expression. Epidermal overexpression of MMP-2 was correlated to angiogenic processes.

A novel dermal matrix generated from burned skin as a promising substitute for deep-degree burns therapy

The extensive skin defects induced by severe burns are dangerous and can be fatal. Currently, the most common therapy is tangential excision to remove the necrotic or denatured areas of skin, followed by skin grafting. Xenogeneic dermal substitutes, such as porcine acellular dermal matrix (ADM), are typically used to cover the burn wounds, and may accelerate wound healing. It is assumed that burned skin that still maintains partial biological activity may be recycled to construct an autologous acellular dermal matrix, termed 'deep‑degree burned dermal matrix (DDBDM)'. In theory, DDBDM may avoid the histoincompatibility issues associated with foreign or xenogeneic dermal matrices, and reduce therapy costs by making full use of discarded skin. In the present study, the collagens within prepared DDBDM were thickened, disorganized and partially fractured, however, they still maintained their reticular structure and tensile strength (P<0.01). Through microarray analysis of the cytokines present in ADM and DDBDM, it was determined that the DDBDM did not produce excessive levels of harmful burn toxins. Following 4 weeks of subcutaneous implantation, ADM and DDBDM were incompletely degraded and maintained good integrity. No significant inflammatory reaction or rejection were observed, which indicated that ADM and DDBDM have good histocompatibility. Therefore, DDBDM may be a useful material for the treatment of deep‑degree burns.

Age and Nursing Affect the Neonatal Porcine Uterine Transcriptome

The lactocrine hypothesis for maternal programming of neonatal development was proposed to describe a mechanism through which milk-borne bioactive factors, delivered from mother to nursing offspring, could affect development of tissues, including the uterus. Porcine uterine development, initiated before birth, is completed postnatally. However, age- and lactocrine-sensitive elements of the neonatal porcine uterine developmental program are undefined. Here, effects of age and nursing on the uterine transcriptome for 48 h from birth (Postnatal Day [PND] = 0) were identified using RNA sequencing (RNAseq). Uterine tissues were obtained from neonatal gilts (n = 4 per group) within 1 h of birth and before feeding (PND 0), or 48 h after nursing ad libitum (PND 2N) or feeding a commercial milk replacer (PND 2R). RNAseq analysis revealed differentially expressed genes (DEGs) associated with both age (PND 2N vs. PND 0; 3283 DEGs) and nursing on PND 2 (PND 2N vs PND 2R; 896 DEGs). Expression of selected uterine genes was validated using quantitative real-time PCR. Bioinformatic analyses revealed multiple biological processes enriched in response to both age and nursing, including cell adhesion, morphogenesis, and cell-cell signaling. Age-sensitive pathways also included estrogen receptor-alpha and hedgehog signaling cascades. Lactocrine-sensitive processes in nursed gilts included those involved in response to wounding, the plasminogen activator network and coagulation. Overall, RNAseq analysis revealed comprehensive age- and nursing-related transcriptomic differences in the neonatal porcine uterus and identified novel pathways and biological processes regulating uterine development.

High-mobility Group Box Protein-1, Matrix Metalloproteinases, and Vitamin D in Keloids and Hypertrophic Scars

Keloids and hypertrophic scars represent excessive wound healing involving high production of collagen by skin fibroblasts. This review focuses on the role of high-mobility group box protein-1 (HMGB-1), matrix metalloproteinases (MMPs), and vitamin D in these conditions. Although the role of HMGB-1 in keloids and hypertrophic scars is unclear, the effect of HMGB-1 on fibroblasts suggests a profibrotic role and a potential contribution to excessive scarring. MMPs contribute extensively to wound healing and characteristically degrade the extracellular matrix. MMP-1 is decreased in keloids and hypertrophic scars. However, other MMPs, including MMP-2, have been found to be increased and are thought to possibly contribute to keloid expansion through peripheral extracellular matrix catabolism. Many novel therapeutic approaches to keloids and hypertrophic scars target MMPs and aim to increase their levels and catabolic activity. The higher prevalence of keloids in darker skin types may partially be due to a tendency for lower vitamin D levels. The physiologically active form of vitamin D, 1,25(OH)2D3, inhibits the proliferation of keloid fibroblasts, and correlations between vitamin D receptor polymorphisms, such as the TaqI CC genotype, and keloid formation have been reported. Additionally, vitamin D may exert an antifibrotic effect partially mediated by MMPs. Here, we critically discuss whether keloid and hypertrophic scar formation could be predicted based on vitamin D status and vitamin D receptor polymorphisms. Specifically, the findings identified HMGB-1, MMPs, and vitamin D as potential avenues for further clinical investigation and potentially novel therapeutic approaches to prevent the development of keloids and hypertrophic scars.

Immunohistochemical analysis on MMP-2 and MMP-9 for wound age determination

We performed immunohistochemical study combined with morphometrical analyses in order to examine the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9 using 55 human skin wounds of different ages: group I, 0-3 days (n = 16); II, 4-7 days (n = 11); III, 9-14 days (n = 16); and IV, 17-21 days (n = 12). Immunopositive reactions for MMP-2 were observed in all human skin specimens including uninjured skin as control. The number of MMP-2(+) macrophages was significantly increased in accordance with wound ages. In contrast to MMP-2, no MMP-9(+) signals were detected in uninjured and wound specimens aged less than 1 day. However, the number of MMP-9(+) macrophages profoundly appeared in groups II and III. Morphometrically, in all of wound samples aged 9-12 days, MMP-2(+) cell number was more than 20. On the contrary, most of the remaining samples had <20 positive cells. However, only one sample (a 7-day-old wound) showed 21 positive cells. Thus, with regard to practical applicability with forensic safety, MMP-2(+) macrophages of >20 would indicate a wound age of 7-12 days. Additionally, 10 out of 12 wound specimens aged 9-12 days showed the MMP-2(+) cell number of >25, implying that MMP-2(+) cell number of >25 would indicate the wound age of 9-12 days. On the contrary, all wound samples aged 3-14 days except for only one sample had MMP-9(+) cell number of >30, indicating that MMP-9(+) cell number of >30 would indicate the wound age of 3-14 days. Collectively, MMP-2 seemed to be more distinct marker, compared with MMP-9.

[Impact of the local application of collagen on the activity of reparative processes in the lower extremity soft tissue of patients with diabetic foot syndrome]

AIM

To estimate of the rate of reparative processes in the lower extremity (LE) soft tissues of patients with diabetic foot (DF) syndrome in the local application of collagen-containing dressings (CCD) versus standard medical therapy.

MATERIAL AND METHODS

The clinical (sizes, tissue oxygenation), histological, and immunohistochemical markers of reparative processes in LE soft tissues were analyzed in patients with diabetes mellitus during the local application of collagen-containing wound dressings versus standard treatment. Forty-two patients with postrevascularization neuropathic and neuroischemic DF syndrome were examined after standard surgical wound treatment. In the perioperative period, 21 patients received local treatment using CCD and 21 patients had standard treatment.

RESULTS

In the patients using CCD, the area and depth of wound defects could be decreased by 26.4±17.2 and 30.4±25.6%, respectively (p=0.002 vs baseline). In the control group, those were 17.0±19.4 and 16.6±21.6%, respectively (p=0.002). Percutaneous oximetry assessment indicated significantly higher local microhemodynamics in the local collagen treatment group (p<0.05). According to the data of histological examination of wound defect tissues, after 10-day treatment, Group 1 showed a 80% reduction in edema (p<0.05), a 90% disappearance of inflammatory infiltrates (p<0.05), and formation of mature granulation tissue (p<0.05). Immunohistochemical examination revealed a more pronounced rise in the count of macrophages in the derma (p<0.05). When CCD was applied, the level of matrix metalloproteinase tended to more markedly decrease as compared to that in the control group.

CONCLUSION

The findings suggest that the activity of reparative processes in LE soft tissues is enhanced in diabetic patients receiving local collagen therapy versus those having standard treatment. This manifests itself as a decrease in both the area and depth of wounds, enhancement of local tissue perfusion, a reduction of inflammation and a rapider wound transfer from proliferation to the epithelialization phase, as supported by histological and immunohistochemical findings.

Feline eosinophilic dermatoses: a retrospective immunohistochemical and ultrastructural study of extracellular matrix remodelling

BACKGROUND

Feline eosinophilic dermatoses (FEDs) are common diseases of cats with an unknown pathogenesis. They are histologically characterized by an eosinophilic infiltration and often by the presence of flame figures (FFs) and/or areas of loss of tissue architecture, here termed necrotic foci (NF). It has been postulated that an alteration in the degradation of the extracellular matrix could be responsible for these histological features. Matrix metalloproteinases (MMPs) are a group of proteases that are fundamental in extracellular matrix remodelling.

HYPOTHESIS/OBJECTIVES

The aim of the study was to investigate retrospectively the expression of a subgroup of MMPs, in particular MMP-2 and MMP-9 gelatinases, in FEDs. The expression of one of their inhibitors, TIMP-2, was also investigated in order to establish the role of these molecules in the pathogenesis of FEDs. The ultrastructural characteristics of extracellular matrix in FFs and NF were subsequently assessed.

METHODS

Fifty-one formalin-fixed, paraffin-embedded specimens from cutaneous and mucosal biopsies diagnosed as FEDs were investigated immunohistochemically. Two selected samples were processed for electron microscopy.

RESULTS

This study revealed an increased expression of MMP-2 in NF and a decreased expression of this gelatinase in FFs. An imbalance between MMP-2 and TIMP-2 was evident using immunohistochemistry. No significative results were observed for MMP-9 expression. Electron microscopy confirmed the lack of normal collagen fibres in NF, whereas in FFs only occasional, amorphous material was observed among normal collagen fibres.

CONCLUSIONS AND CLINICAL IMPORTANCE

Our study suggests that an imbalance in the expression of matrix metalloproteinases could be responsible for different morphological findings in FEDs. Further studies are needed to assess the role of matrix metalloproteinases in the pathogenesis of FEDs.

Levels of plasma matrix metalloproteinases (MMP-2 and MMP-9) in response to INTEGRA® dermal regeneration template implantation

BACKGROUND

Cutaneous wound healing results in scar formation. Matrix metalloproteinases (MMP) transform extracellular matrix proteins and modulate inflammation and cell signaling, thus determining scar outcome. To provide rapid wound closure and reduced scarring, dermal scaffolds were introduced. Little is known about the influence of these materials on MMPs levels.

MATERIAL AND METHODS

In this in vivo study the levels of MMP-2, MMP-9, and mediators of inflammation and fibrosis (IL-4 and TGF-beta1) in patients treated with Integra® dermal regeneration template (IDRT) were investigated. In the group of 11 pediatric patients treated with IDRT, levels of selected molecules were analyzed before surgery and at day 1, 7, and 25 after scaffold implantation.

RESULTS

The mean IDRT take rate was 89.5 ± 4.7% with 4 patients (36%) who developed local infection. Patients were divided into 2 groups according to presence of infection (1 group with complications and 1 group without complications). In the group with complications, the IDRT take rate was significantly reduced compared to the group without complications (71.5 ± 5.4 vs. 100 ± 0.1; p<0.005). Plasma levels of MMP-2 were significantly (p<0.05) elevated in both groups on day 7 after the scaffold placement compared to baseline. Positive correlations between IL-4 and MMP-2 (p=0.01) in the group with complications and TGF-beta1 and MMP-9 (p=0.012) in both groups were observed.

CONCLUSIONS

These findings suggest that Integra® scaffold degradation is mainly caused by MMP-2, whereas inflammation associated with local infection increases levels of this molecule and it is not associated with elevation of MMP-9. This shows that dermal regeneration with Integra® uses molecular mechanisms other than scar formation during dermal wound healing.

Sanguinarine inhibits invasiveness and the MMP-9 and COX-2 expression in TPA-induced breast cancer cells by inducing HO-1 expression

Most complications of breast cancer are attributed to metastasis to distant organs, including lymph nodes, bone, lung and liver. Metastasis is considered the leading cause of mortality in patients with breast cancer. The emergence of anti-metastatic properties in breast cancer is an important clinical phenomenon affecting long-term survival. In the present study, we investigated the anti-invasive mechanism of sanguinarine by focusing on its role in inducing HO-1 in breast cancer cells. The results showed that sanguinarine inhibited TPA-induced MMP-9 and COX-2 mRNA and protein expression in a dose-dependent manner at non-cytotoxic concentrations. Similarly, the MMP-9 enzymatic activity and the PGE2 levels significantly decreased in MCF-7 breast cancer cells. TIMP-1 and TIMP-2, specific endogenous inhibitors of MMP-9, were slightly induced by sanguinarine. Subsequent studies revealed that sanguinarine suppressed TPA-induced NF-κB and AP-1 activation, as well as the phosphorylation of Akt and ERK. Furthermore, sanguinarine significantly inhibited TPA-induced invasion and migration in breast cancer cells. We also demonstrated that sanguinarine induced HO-1 expression, and that the inhibition of MMP-9 and COX-2 expression and the enzymatic activity of sanguinarine were abrogated by siRNA-mediated knockdown of HO-1 expression. Thus, knockdown of endogenous HO-1 decreased TPA-induced cell invasion. Overall, the results of the present study demonstrate that HO-1 plays a pivotal role in the anti-invasive response of sanguinarine in TPA-stimulated breast cancer cells.

Uniaxial cyclic strain stimulates cell proliferation and secretion of interleukin-6 and vascular endothelial growth factor of human dermal fibroblasts seeded on chitosan scaffolds

Human dermal fibroblasts were inoculated into chitosan sponge scaffolds coated with type I collagen and it might be developed as a dermal substitute and/or dressing material. The application of 14% uniaxial cyclic strain to the cellular scaffolds affected the characteristics of the seeded human dermal fibroblasts. Cyclic strain enhanced cellular proliferation, the activity of metalloproteinase-2, and the expression of extracellular matrix proteins such as fibronectin. Moreover, cyclic strain increased the expression of vascular endothelial growth factor (VEGF) and interleukin (IL)-6, which are critical to wound healing. Even under static culture (strain, 0%) following 14% cyclic strain, the expression of VEGF and IL-6, which had increased under 14% strain, was amplified or maintained for at least 3 days. Uniaxial cyclic strain may enhance the wound-healing potential of human dermal fibroblasts seeded on chitosan scaffolds through the changes in the cellular characteristics of the fibroblasts when the cellular scaffold is transplanted into skin wounds, especially chronic wounds such as diabetic wounds.

Transforming Growth Factor-β and Endoglin Signaling Orchestrate Wound Healing

Physiological wound healing is a complex process requiring the temporal and spatial co-ordination of various signaling networks, biomechanical forces, and biochemical signaling pathways in both hypoxic and non-hypoxic conditions. Although a plethora of factors are required for successful physiological tissue repair, transforming growth factor beta (TGF-β) expression has been demonstrated throughout wound healing and shown to regulate many processes involved in tissue repair, including production of ECM, proteases, protease inhibitors, migration, chemotaxis, and proliferation of macrophages, fibroblasts of the granulation tissue, epithelial and capillary endothelial cells. TGF-β mediates these effects by stimulating signaling pathways through a receptor complex which contains Endoglin. Endoglin is expressed in a broad spectrum of proliferating and stem cells with elevated expression during hypoxia, and regulates important cellular functions such as proliferation and adhesion via Smad signaling. This review focuses on how the TGF-β family and Endoglin, regulate stem cell availability, and modulate cellular behavior within the wound microenvironment, includes current knowledge of the signaling pathways involved, and explores how this information may be applicable to inflammatory and/or angiogenic diseases such as fibrosis, rheumatoid arthritis and metastatic cancer.

Effects of hepatocyte growth factor on collagen synthesis and matrix metalloproteinase production in keloids

Keloids are pathologic proliferations of the dermal layer of the skin resulting from excessive collagen production and deposition. Hepatocyte growth factor (HGF) increases the expression of matrix metalloproteinase (MMP)-1 and suppresses collagen synthesis to modulate extracellular matrix turnover. To investigate the anti-fibrotic effects of HGF, we examine the mRNA expression of collagen types I and III and matrix metalloproteinase (MMP-1, MMP-3) on human dermal fibroblast (HDF) cell lines and keloid fibroblasts (KFs, n = 5) after adding various amount of HGF protein. We also evaluated the enzymatic activity of MMP-2, MMP-9 by zymograghy. In HDFs treated with TGF-β1 and HGF protein simultaneously, both type I and III collagen mRNA expression significantly decreased (P < 0.05). Expression of MMP-1, MMP-3 mRNA also decreased. However, the mRNA expression of MMP-1, MMP-3 significantly increased in KFs with increasing amount of HGF in dose dependent manner (P < 0.05). The enzymatic activities of MMP-2 increased with increasing HGF protein in a dose-dependent manner. However, the enzymatic activity of MMP-9 did not change. These results suggest that the anti-fibrotic effects of HGF may have therapeutic effects on keloids by reversing pathologic fibrosis.

Wound healing properties of jojoba liquid wax: an in vitro study

AIM OF THE STUDY

The wound healing properties of jojoba (Simmondsia chinensis) liquid wax (JLW) were studied in vitro on HaCaT keratinocytes and human dermal fibroblasts, which are involved in wounded skin repair.

MATERIALS AND METHODS

JLW cytotoxicity was evaluated by the crystal violet staining and the neutral red uptake endpoint. Induction of wound healing by JLW was assessed by scratch wound assay on cell monolayers. The involvement of signaling pathways was evaluated by the use of the Ca(2+) chelator BAPTA and of kinase inhibitors, and by Western blot analysis of cell lysates using anti-phospho antibodies. Collagen and gelatinase secretion by cells were assayed by in-cell ELISA and zymography analysis, respectively.

RESULTS

Cytotoxicity assays showed that the toxic effects of JLW to these cells are extremely low. Scratch wound experiments showed that JLW notably accelerates the wound closure of both keratinocytes and fibroblasts. The use of inhibitors and Western blot revealed that the mechanism of action of JLW is strictly Ca(2+) dependent and requires the involvement of the PI3K-Akt-mTOR pathway and of the p38 and ERK1/2 MAPKs. In addition, JLW was found to stimulate collagen I synthesis in fibroblasts, while no effect was detected on the secretion of MMP-2 and MMP-9 gelatinases by HaCaT or fibroblasts.

CONCLUSIONS

Taken together, data provide a pharmacological characterization of JLW properties on skin cells and suggest that it could be used in the treatment of wounds in clinical settings.

Irradiation of normal mouse tissue increases the invasiveness of mammary cancer cells

PURPOSE

Treatment of breast tumours frequently involves irradiating the whole breast to reach malignant microfoci scattered throughout the breast. In this study, we determined whether irradiation of normal tissues could increase the invasiveness of breast cancer cells in a mouse model.

MATERIALS AND METHODS

Non-irradiated MC7-L1 mouse mammary carcinoma cells were injected subcutaneously in irradiated and non-irradiated thighs of Balb/c mice. The invasion volume, tumour volume, blood vessel permeability and interstitial volumes were monitored by magnetic resonance imaging (MRI). Slices of normal tissue invaded by cancer cells were examined by histology. Activity of matrix metalloproteinase -2 and -9 (MMP -2 and -9) in healthy and irradiated tissues was determined, and the proliferation index of the invading cancer cells was evaluated.

RESULTS

Three weeks after irradiation, enhancement of MC7-L1 cells invasiveness in irradiated thighs was already detected by MRI. The tumour invasion volume continued to extend 28- to 37-fold compared to the non-irradiated implantation site for the following three weeks, and it was associated with an increase of MMP-2 and -9 activities in healthy tissues. The interstitial volume associated with invading cancer cells was significantly larger in the pre-irradiated sites; while the blood vessels permeability was not altered. Cancer cells invading the healthy tissues were proliferating at a lower rate compared to non-invading cancer cells.

CONCLUSION

Implantation of non-irradiated mammary cancer cells in previously irradiated normal tissue enhances the invasive capacity of the mammary cancer cells and is associated with an increased activity of MMP-2 and -9 in the irradiated normal tissue.

Angiopoietin-1, angiopoietin-2 and Tie-2 receptor expression in human dermal wound repair and scarring

BACKGROUND

The angiopoietin (Ang)/Tie-2 ligand/receptor system is known to interact with the vascular endothelial growth factor (VEGF) pathway to determine the fate of blood vessels during angiogenesis. However, the precise contribution of this system to angiogenesis and the mechanisms of vascular maturation and remodelling in human tissue repair have yet to be elucidated.

OBJECTIVES

To examine the spatial and temporal expression of Ang-1, Ang-2, Tie-2 and VEGF in relation to angiogenesis in human surgical wounds.

METHODS

Punch biopsies were taken either from normal unwounded skin (controls) during surgery or from mastectomy scars between 3 days and 2 years postsurgery. Ang-1, Ang-2, Tie-2 and VEGF fibroblast/myofibroblast and endothelial expression were characterized by immunohistochemistry, analysed semiquantitatively and correlated with microvessel density (MVD) and scar age.

RESULTS

The expression of VEGF, Ang-1, Ang-2 and Tie-2 in fibroblasts/myofibroblasts was increased significantly in early scars, decreased in older scars and was related to scar age (P < 0·001) and MVD (P < 0·0004), with strong correlations between all factors. In contrast, vascular expression of Ang-1 was decreased slightly in early scars, vascular Ang-2 remained constant and Tie-2 vascular expression increased, although there were no correlations with scar age or MVD.

CONCLUSIONS

These data demonstrate that angiopoietins and their receptor, Tie-2, are expressed in both fibroblasts/myofibroblasts and endothelial cells in healing human wounds. Fibroblast/myofibroblast expression correlates with angiogenesis and VEGF expression, suggesting a role for the angiopoietin/Tie-2 system in normal wound repair and scarring.

Platelet lysate modulates MMP-2 and MMP-9 expression, matrix deposition and cell-to-matrix adhesion in keratinocytes and fibroblasts

Cell-matrix interactions are an essential element of wound healing, while platelet derivatives are used in clinical settings for the treatment of chronic wounds. We used a platelet lysate (PL), which had been previously shown to accelerate in vitro the wounding of HaCaT keratinocytes and fibroblasts (J Cell Mol Med, 13, 2009, 2030; Br J Dermatol, 159, 2008, 537), to study the modulation of MMP-2 and MMP-9 collagenase expression, collagen type I and III production and syndecan-4 expression and rearrangement in these cells. Zymography and Western blot analyses showed that exposure to 20% (v/v) PL for 24 h induced an apparently ERK1/2- and p38-dependent, NF-kappaB-independent, translational upregulation of MMP-9 in HaCaT, while HaCaT MMP-2 and fibroblast collagenases were almost unaffected. The use of in-cell ELISA showed that PL induced an increase in the collagen III production of fibroblasts. In-cell ELISA and immunofluorescence microscopy revealed an increase in the expression of syndecan-4 and its rearrangement to form focal adhesions in both cell types after PL exposure. Taken together, data indicate that PL promotes keratinocyte epithelialization and regulates fibroblast matrix deposition, thus providing a molecular basis for the ability of this platelet derivative to heal severe and problematic wounds without leading to heavy scarring and keloid formation.

The imbalanced expression of matrix metalloproteinases in nephrogenic systemic fibrosis

BACKGROUND

Nephrogenic systemic fibrosis (NSF) occurs in patients with renal dysfunction and gadolinium exposure. Although little is known about the pathogenesis of this disease, increased expression of transforming growth factor-beta has been recently demonstrated. Other fibrosing conditions have been shown to express an imbalance in matrix metalloproteinase (MMP) expression and their corresponding inhibitors. Myofibroblast differentiation, in which cells often express alpha-smooth muscle actin and achieve the ability to contract, is also a hallmark of fibrosis.

OBJECTIVE

We theorized that NSF may overexpress tissue inhibitor of metalloproteinase-1 (TIMP-1), while simultaneously showing decreased expression of MMP-1. As a secondary aim, we sought to evaluate the presence of smooth muscle actin in our samples.

METHODS

We applied immunohistochemistry to 16 skin biopsies from 10 patients with NSF using antibodies to TIMP-1, MMP-1, MMP-2, MMP-9, and alpha-smooth muscle actin. Samples from normal skin, scar, keloid and scleroderma were stained for comparison.

RESULTS

TIMP-1 was strongly expressed in all NSF specimens compared to normal skin. MMP-1 expression was nearly absent in all tested samples. In all 16 NSF cases, the dermal spindle cells did not stain for alpha-smooth muscle actin. MMP-2 and MMP-9 expression was variable but was increased compared to normal skin.

LIMITATIONS

The expression is semiquantitative and based on immunohistochemistry and unconfirmed by other techniques.

CONCLUSIONS

In NSF, TIMP-1 is strongly expressed and MMP-1 is nearly absent, characteristic of the MMP imbalances seen in other fibrosing processes. Using smooth muscle actin immunohistochemistry, there was no evidence of myofibroblast differentiation.

Matrix metalloproteinase-2 and -9 activities in human keloids, hypertrophic and atrophic scars: a pilot study

Proteolytic degradation of extracellular matrix is one of the principal features of cutaneous wound healing but little is known about the activities of gelatinases; matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) on abnormal scar formation. The aim of this study is to determine collagen levels and the gelatinase activities in tissue from hypertrophic scars, atrophic scars, keloids and donor skin in 36 patients and 14 donors. Gelatinase levels (proenzyme + active enzyme) were determined by ELISA and their activities by gelatin zymography. MMP-9 activity was undetectable in gelatin zymography analysis. Pro-MMP-2 levels (median) were highest in normal skin group 53.58 (36.40-75.11) OD microg(-1) protein, while active MMP-2 levels were highest in keloid group 52.53 (42.47-61.51) OD microg(-1) protein. The active/pro ratio was the highest in keloid group 0.97 followed by hypertrophic scar, normal skin and atrophic scar groups 0.69 > 0.54 > 0.48, respectively. According to results of our study, the two-phase theory of the duration of hypertrophic scar and keloid formation can be supported by the data of tissue collagen and gelatinase analysis. This study is the first to relate scar formation relationship in regard to gelatinase activation ratio in a keloid, hypertrophic and atrophic scar patient group which is chosen appropriate in age and sex.

Matrix metalloproteinases in inflammatory pathologies of the horse

The extracellular matrix (ECM) of connective tissue is constantly being remodelled to allow for growth and regeneration. Normal tissue maintenance requires the ECM components to be degraded and re-synthesised in relatively equal proportions. This degradation is facilitated by matrix metalloproteinases (MMPs) and their proteolytic action is controlled primarily by the tissue inhibitors of metalloproteinases (TIMPs). Both MMPs and TIMPs exist in a state of dynamic equilibrium, with a slight excess of one or the other depending on the need for either ECM breakdown or synthesis. Long-term disruption to this balance between MMPs and TIMPs will have pathological consequences. Matrix metalloproteinases are involved in a number of diseases in mammals, including the horse. Excess MMP activity can cause ECM destruction, as seen in the lamellar basement membrane in laminitis and the articular cartilage in osteoarthritis. Matrix metalloproteinase under-activity can potentially impede healing by preventing fibrinolysis in fibrotic conditions and the removal of scar tissue in wounds. Matrix metalloproteinases also degrade non-ECM proteins and regulate cell behaviour via the release of growth factors from the substrates they cleave, increasing the scope of their effects. This review looks at the involvement of MMPs in equine health and pathologies, whilst exploring the potential consequences of therapeutic intervention.

alpha-Lipoic acid modulates extracellular matrix and angiogenesis gene expression in non-healing wounds treated with hyperbaric oxygen therapy

alpha-Lipoic acid (LA) has been found previously to accelerate wound repair in patients affected by chronic wounds who underwent hyperbaric oxygen (HBO) therapy. Because proteinases are important in wound repair, we hypothesized that LA may regulate matrix metalloproteinase (MMP) expression in cells that are involved in wound repair. Patients undergoing HBO therapy were double-blind randomized into two groups: the LA group and the placebo group. Gene expression profiles for MMPs and for angiogenesis mediators were evaluated in biopsies collected at the first HBO session, at the seventh HBO session, and after 14 days of HBO treatment. ELISA tests were used to validate microarray expression of selected genes. LA supplementation in combination with HBO therapy downregulated the inflammatory cytokines and the growth factors which, in turn, affect MMPs expression. The disruption of the positive autocrine feedback loops that maintain the chronic wound state promotes progression of the healing process.

The management of postacne scarring

BACKGROUND

Therapeutic intervention for postacne scarring has historically been limited by the considerable morbidity of most treatments for only marginal disease improvement. Within the past decade, however, a greater understanding of the pathogenesis of acne scarring has led to the development of techniques that offer more favorable risk-benefit profiles.

OBJECTIVE

The aims of this article are to highlight a number of newer techniques and to assign their appropriateness to particular grades of acne scarring.

MATERIALS AND METHODS

Current modalities are discussed as they relate to disease process and specific acne scar types. Techniques are presented in order of most effectual therapeutic interventions for defined grades of acne scarring. Acne scarring grades have been described previously in terms of disease load, severity, and lesion morphologies.

RESULTS

A comprehensive discussion of updated therapeutic techniques and their biologic rationales in the treatment of acne scarring is presented. These include targeted interventions of inflammatory and postinflammatory processes, angiogenesis, immunologic processes, dermal and subcutaneous fibrosis, hypertrophy, and keloid scarring.

DISCUSSION

A requirement for developing successful treatments for postacne scarring is a greater understanding of its pathogenesis, variability among afflicted individuals, and the inflammatory mediators and immunology of the scarring process. Many innovative techniques introduced in the past decade attempt to counteract these pathologic processes while keeping the procedural and postoperative risks to a minimum.

In vitro irradiation of basement membrane enhances the invasiveness of breast cancer cells

Following removal of the primary breast tumour by conservative surgery, patients may still have additional malignant foci scattered throughout the breast. Radiation treatments are not designed to eliminate all these residual cancer cells. Rather, the radiation dose is calculated to optimise long-term results with minimal complications. In a tumour, cancer cells are surrounded by a basement membrane, which plays an important role in the regulation of gene expression. Using an invasion chamber, we have shown that irradiation before cell plating of a reconstituted basement membrane (Matrigel; Becton Dickinson, Bedford, MA, USA) increased the invasiveness of the breast cancer cells MDA-MB-231. This radiation enhancement of invasion was associated with the upregulation of the pro-invasive gene matrix metalloproteinase (MMP)-2. The expression of membrane type 1 matrix metalloproteinase (MT1-MMP) and tissue inhibitor of metalloproteinase-2 (TIMP), which are required to activate the MMP-2, were also increased. Confirming the role of MMP-2 and MT1-MMP, radiation enhancement of cancer cell invasion was prevented by an MMP-2 inhibitor and an anti-MT1-MMP antibody. This study also demonstrated that radiation can potentially enhance the invasion ability by inducing the release of pro-invasive factors stored in the Matrigel. Conversely, no enhancement of invasiveness was observed with the low metastatic cell line MCF-7. This lack of invasiveness correlated with the absence of the MMP-2 activator MT1-MMP in the MCF-7 cells. Radiotherapy is an efficient modality to treat breast cancer which could be further improved by inhibiting the pro-invasive gene upregulated by radiation.

Zinc in wound healing: theoretical, experimental, and clinical aspects

Zinc is an essential trace element in the human body and its importance in health and disease is appreciated. It serves as a cofactor in numerous transcription factors and enzyme systems including zinc-dependent matrix metalloproteinases that augment autodebridement and keratinocyte migration during wound repair. Zinc confers resistance to epithelial apoptosis through cytoprotection against reactive oxygen species and bacterial toxins possibly through antioxidant activity of the cysteine-rich metallothioneins. Zinc deficiency of hereditary or dietary cause can lead to pathological changes and delayed wound healing. Oral zinc supplementation may be beneficial in treating zinc-deficient leg ulcer patients, but its therapeutic place in surgical patients needs further clarification. Topical administration of zinc appears to be superior to oral therapy due to its action in reducing superinfections and necrotic material via enhanced local defense systems and collagenolytic activity, and the sustained release of zinc ions that stimulates epithelialization of wounds in normozincemic individuals. Zinc oxide in paste bandages (Unna boot) protects and soothes inflamed peri-ulcer skin. Zinc is transported through the skin from these formulations, although the systemic effects seem insignificant. We present here the first comprehensive account of zinc in wound management in relation to current concepts of wound bed preparation and the wound-healing cascade. This review article suggests that topical zinc therapy is underappreciated even though clinical evidence emphasizes its importance in autodebridement, anti-infective action, and promotion of epithelialization.

Induction of MMP-9 release from human dermal fibroblasts by thrombin: involvement of JAK/STAT3 signaling pathway in MMP-9 release

Background

It has been recognized that dermal fibroblasts and matrix metalloproteases (MMP) play crucial roles in wound healing process in skin. Thrombin was found to stimulate IL-8 release from human dermal fibroblasts (HDFs). However, little is known of the effect of thrombin on secretion of MMPs from dermal fibroblasts. In the present study, the influence of thrombin on proMMP-2 and proMMP-9 activity release from primary cultured HDFs, and its potential signaling pathways were investigated.

Results

The results showed that thrombin induced proMMP-9, but not proMMP-2 release from HDFs in a dose dependent manner at 6 h following incubation. Thrombin also upregulated expression of proMMP-9 mRNA in HDFs. Hirudin completely abolished the action of thrombin on HDFs. An agonist peptide of protease-activated receptor-1, SFLLR-NH₂ stimulated an enhanced release of proMMP-9 from HDFs. AG490, an inhibitor of STAT3 inhibited basal and thrombin-provoked proMMP-9 release and phosphorylation of STAT3. PD98059, an inhibitor of MAPK and LY294002, an inhibitor PI3K failed to significantly inhibit thrombin induced proMMP-9 release.

Conclusion

Thrombin is a potent stimulus of proMMP-9 release from HDFs. Thrombin induced proMMP-9 release is most likely through activation of PAR-1. JAK/STAT3 signaling pathway is involved in proMMP-9 release from HDFs.

Interleukin-6 (IL-6) modulates migration and matrix metalloproteinase function in dermal fibroblasts from IL-6KO mice

BACKGROUND

Interleukin-6-deficient (IL-6KO) mice display significantly delayed cutaneous wound healing characterized by decreased re-epithelialization, granulation tissue and wound closure. Dermal fibroblasts are one of the principal cell types found in granulation tissue and mediate numerous processes during healing.

OBJECTIVES

To investigate the effects that IL-6 might have on granulation tissue formation and fibroblast motility. As fibroblast motility is associated with matrix metalloproteinase (MMP) activity, the expression of MMP-2 and the tissue inhibitors of metalloproteinase (TIMP)-1 and -2 were assessed.

METHODS

Punch biopsies (4 mm) were performed in the skin of IL-6KO and C57BL/6 mice. The expression of MMP-2, TIMP-1 and -2 in wound tissue was monitored over time. Cellular infiltration and granulation tissue formation was monitored by subcutaneous implantation of polyvinyl alcohol (PVA) sponges. A free-floating collagen lattice model was also used to investigate the direct effects of IL-6 treatment on isolated IL-6KO fibroblasts. The expression of MMP-2, and the inhibitors TIMP-1 and -2, were assessed via real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

IL-6KO wounds showed impaired granulation tissue formation 5 days postwounding and fewer fibroblasts had populated the PVA matrices 7 days after implantation in IL-6KO mice compared with wild-type C57BL/6. The mRNA and protein expression of MMP-2 and TIMP-2 mRNA was increased in IL-6KO mice compared with wild-type mice beyond 1 day postwounding, while the expression of TIMP-1 mRNA was transiently higher in IL-6KO only 3 days postwounding. Treatment of collagen lattices with various concentrations of rmIL-6 again showed a dose-response decrease in mRNA and protein expression of MMP-2 and TIMP-2 protein expression, compared with saline control, while TIMP-1 did not appear to be significantly modulated.

CONCLUSIONS

These results indicate that IL-6 influences the function of fibroblasts in wounds, and one mechanism of this regulation may be through the modulation of MMP-2 and TIMP proteins.

Expression of angiogenic and fibrogenic factors in proliferative vitreoretinal disorders

PURPOSE

To investigate the expression of connective tissue growth factor (CTGF) in the retina of human subjects with diabetes mellitus, and CTGF, CD105, and gelatinase B in proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR) epiretinal membranes.

METHODS

Twelve donor eyes from six subjects with diabetes mellitus, 10 eyes from five nondiabetic subjects, 14 PDR membranes, and five PVR membranes were studied by immunohistochemical techniques. In situ zymography was used to examine gelatinolytic activity in four PDR membranes.

RESULTS

In nondiabetic retinas, there was no immunoreactivity for CTGF. Diabetic retinas showed immunoreactivity for CTGF in ganglion cells and microglia. Vascular endothelial cells in PDR membranes expressed CTGF, CD105, and gelatinase B in 10 (71.4%), 11 (78.6%), and 5 (35.7%) membranes, respectively. Myofibroblasts in PDR membranes expressed CTGF, and gelatinase B in 14 (100%), and 6 (42.9%) membranes, respectively. There was a significant correlation between the number of blood vessels expressing the panendothelial marker CD34 and the number of blood vessels expressing CTGF (r = 0.7884; P = 0.0008), and CD105 (r = 0.6901; P = 0.0063), and the number of myofibroblasts expressing CTGF (r = 0.5922; P = 0.0257). There was a significant correlation between the number of myofibroblasts expressing alpha-smooth muscle actin and the number of myofibroblasts expressing CTGF (r = 0.8393; P = 0.0002). In situ zymography showed the presence of gelatinolytic activity in vascular endothelial cells in PDR membranes. Myofibroblasts in PVR membranes expressed CTGF, and gelatinase B.

CONCLUSIONS

These results suggest a possible role of CTGF, CD105, and gelatinase B in the pathogenesis of proliferative vitreoretinal disorders.

Differential expression of matrix metalloproteinases and tissue-derived inhibitors of metalloproteinase in fetal and adult skins

Matrix metalloproteinases and their tissue-derived inhibitors determine the architecture of the extracellular matrix. In early gestation, the amount and organization of extracellular matrix may be associated with scarless repair of fetal skin wounds. To elucidate the part of the mechanism(s) underlying the phenotypic transition from scarless to scar-forming healing observed during fetal gestation, the ontogeny of matrix metalloproteinase-2, -9, -14 and their tissue inhibitors was characterized in non-wounded fetal human skin with different gestational ages from 13 to 33 weeks and adult skin using reverse transcriptase-polymerase chain reaction, immunohistochemical staining and western blot protocols. We showed that the levels of gene expressions for matrix metalloproteinase-2, -9, -14 and their endogenous inhibitors were significantly more in late gestational and adult skins than that in early gestational skin. Similar results were noted in terms of protein contents of these enzymes and inhibitors in fetal and adult skins. We concluded that the endogenous matrix metalloproteinase-2, -9, -14 and their endogenous inhibitors might be involved in skin development and in maintenance of cutaneous structure and function. Lower protein contents of tissue-derived inhibitor-1, -2 in early gestational skin might provide a predominantly antiscarring signal while higher protein expression of these two inhibitors might be associated with scar-forming healing in late gestational and adult skins.

Macrophage matrix metalloproteinase-2/-9 gene and protein expression following adhesion to ECM-derived multifunctional matrices via integrin complexation

Macrophages are commonly observed at the biomaterial-tissue interface and interact with the extracellular matrix (ECM) mainly by integrin receptors to play a critical role in ECM turnover by secreting matrix metalloproteinases (MMPs). To investigate beta1 and beta3 containing integrin-mediated adhesion and subsequent MMP-2/-9 protein and gene expression in human blood-derived monocytes, biofunctional peptides immobilized onto flexible polyethylene glycol (PEG) arms were grafted onto a gelatin-based interpenetrating network (IPN). Adherent monocyte density was dramatically greater in the presence of RGD immobilized onto flexible PEG arms of the gelatin-based IPN. Pretreatment of monocytes with either anti-integrin beta1 or beta3 led to a significant decrease in adherent cell density on RGD-PEG-grafted IPNs. MMP-2 and MMP-9 protein and MMP-9 mRNA expression increased in the presence of IPNs initially, independent of ligand identity. Anti-integrin beta1 or beta3 antibody pretreatment of monocytes led to a general decrease in MMP-2/-9 protein expression. These results demonstrate the importance of beta1 and beta3 containing integrins in mediating monocyte adhesion onto RGD immobilized onto flexible PEG arms of the IPN. The results also reveal that MMP-2/-9 protein and gene expression is influenced by the presence of gelatin and not the ligands immobilized on the PEG arms of the IPN.

Thymosin beta4 promotes matrix metalloproteinase expression during wound repair

Immobilized patients, diabetics, and the elderly suffer from impaired wound healing. The 43-amino acid angiogenic peptide thymosin beta4 (Tbeta4) has previously been found to accelerate dermal wound repair in rats, aged mice, and db/db diabetic mice. It also promotes corneal repair in both normal rats and mice. Because proteinases are important in wound repair, we hypothesized that Tbeta4 may regulate matrix metalloproteinase (MMP) expression in cells that are involved in wound repair. Analysis by RT-PCR of whole excised mouse dermal wounds on days 1, 2, and 3 after wounding showed that Tbeta4 increased several metalloproteinases, including MMP-2 and -9 expression by several-fold over control on day 2 after wounding. We further analyzed the metalloproteinases secreted in response to exogenous Tbeta4 by cells normally present in the wound. Western blot analysis of cultured keratinocytes, endothelial cells, and fibroblasts that were treated with increasing concentrations of Tbeta4 showed increases in the levels of MMP-1, -2, and -9 in a cell-specific manner. Tbeta4 also enhanced the secretion of MMP-1 and MMP-9 by activated monocytes. The central actin-binding domain, amino acids 17-23, had all of the activity for metalloproteinase induction. We conclude that part of the wound healing activity of Tbeta4 resides in its ability to increase proteinase activity via its central actin-binding domain. Thus, Tbeta4 may play a pivotal role in extracellular matrix remodeling during wound repair.