Collagenase in wound healing: effect of wound age and type

Neural and Inflammatory Interactions in Wound Healing

ABSTRACT

The skin is an intricate network of both neurons and immunocytes, where emerging evidence has indicated that the regulation of neural-inflammatory processes may play a crucial role in mediating wound healing. Disease associated abnormal immunological dysfunction and peripheral neuropathy are implicated in the pathogenesis of wound healing impairment. However, the mechanisms through which neural-inflammatory interactions modulate wound healing remain ambiguous. Understanding the underlying mechanisms may provide novel insights to develop therapeutic devices, which could manipulate neural-inflammatory crosstalk to aid wound healing. This review aims to comprehensively illustrate the neural-inflammatory interactions during different stages of the repair process. Numerous mediators including neuropeptides secreted by the sensory and autonomic nerve fibers and cytokines produced by immunocytes play an essential part during the distinct phases of wound healing.

Latest Insights into the In Vivo Studies in Murine Regarding the Role of TRP Channels in Wound Healing-A Review

Wound healing involves physical, chemical and immunological processes. Transient receptor potential (TRP) and other ion channels are implicated in epidermal re-epithelization. Ion movement across ion channels can induce transmembrane potential that leads to transepithelial potential (TEP) changes. TEP is present in epidermis surrounding the lesion decreases and induces an endogenous direct current generating an epithelial electric field (EF) that could be implicated in wound re-epithelialization. TRP channels are involved in the activation of immune cells during mainly the inflammatory phase of wound healing. The aim of the study was to review the mechanisms of ion channel involvement in wound healing in in vivo experiments in murine (mice, rats) and how can this process be influenced. This review used the latest results published in scientific journals over the last year and this year to date (1 January 2023-31 December 3000) in order to include the in-press articles. Some types of TRP channels, such as TRPV1, TRPV3 and TRPA1, are expressed in immune cells and can be activated by inflammatory mediators. The most beneficial effects in wound healing are produced using agonists of TRPV1, TRPV4 and TRPA1 channels or by inhibiting with antagonists, antisense oligonucleotides or knocking down TRPV3 and TRPM8 channels.

Gelatin methacryloyl granular scaffolds for localized mRNA delivery

mRNA therapy is the intracellular delivery of messenger RNA (mRNA) to produce desired therapeutic proteins. Developing strategies for local mRNA delivery is still required where direct intra-articular injections are inappropriate for targeting a specific tissue. The mRNA delivery efficiency depends on protecting nucleic acids against nuclease-mediated degradation and safe site-specific intracellular delivery. Herein, we report novel mRNA-releasing matrices based on RGD-moiety-rich gelatin methacryloyl (GelMA) microporous annealed particle (MAP) scaffolds. GelMA concentration in aerogel-based microgels (μgels) produced through a microfluidic process, MAP stiffnesses, and microporosity are crucial parameters for cell adhesion, spreading, and proliferation. After being loaded with mRNA complexes, MAP scaffolds composed of 10 % GelMA μgels display excellent cell viability with increasing cell infiltration, adhesion, proliferation, and gene transfer. The intracellular delivery is achieved by the sustained release of mRNA complexes from MAP scaffolds and cell adhesion on mRNA-releasing scaffolds. These findings highlight that hybrid systems can achieve efficient protein expression by delivering mRNA complexes, making them promising mRNA-releasing biomaterials for tissue engineering.

Wound healing, scarring and management

Understanding wound healing is imperative for the dermatological physician to optimize surgical outcomes. Poor healing may result in negative functional, cosmetic and psychological sequelae. This review briefly outlines the physiology of wound healing, with a view to improving the management of wounds and scars, and minimizing the long-term scarring complications.

Enzymes for dermatological use

Skin is the ultimate barrier between body and environment and prevents water loss and penetration of pathogens and toxins. Internal and external stressors, such as ultraviolet radiation (UVR), can damage skin integrity and lead to disorders. Therefore, skin health and skin ageing are important concerns and increased research from cosmetic and pharmaceutical sectors aims to improve skin conditions and provide new anti-ageing treatments. Biomolecules, compared to low molecular weight drugs and cosmetic ingredients, can offer high levels of specificity. Topically applied enzymes have been investigated to treat the adverse effects of sunlight, pollution and other external agents. Enzymes, with a diverse range of targets, present potential for dermatological use such as antioxidant enzymes, proteases and repairing enzymes. In this review, we discuss enzymes for dermatological applications and the challenges associated in this growing field.

Electrospun methacrylated natural/synthetic composite membranes for gingival tissue engineering

New functional materials for engineering gingival tissue are still in the early stages of development. Materials for such applications must maintain volume and have advantageous mechanical and biological characteristics for tissue regeneration, to be an alternative to autografts, which are the current benchmark of care. In this work, methacrylated gelatin (GelMa) was photocrosslinked with synthetic immunomodulatory methacrylated divinyl urethanes and defined monomers to generate composite scaffolds. Using a factorial design, with the synthetic monomers of a degradable polar/hydrophobic/ionic polyurethane (D-PHI) and GelMa, composite materials were electrospun with polycarbonate urethane (PCNU) and light-cured in-flight. The materials had significantly different relative hydrophilicities, with unique biodegradation profiles associated with specific formulations, thereby providing good guidance to achieving desired mechanical characteristics and scaffold resorption for gingival tissue regeneration. In accelerated esterase/collagenase degradation models, the new materials exhibited an initial rapid weight loss followed by a more gradual rate of degradation. The degradation profile allowed for the early infiltration of human adipose-derived stromal/stem cells, while still enabling the graft's structural integrity to be maintained. In conclusion, the materials provide a promising candidate platform for the regeneration of oral soft tissues, addressing the requirement of viable tissue infiltration while maintaining volume and mechanical integrity. STATEMENT OF SIGNIFICANCE: There is a need for the development of more functional and efficacious materials for the treatment of gingival recession. To address significant limitations in current material formulations, we sought to investigate the development of methacrylated gelatin (GelMa) and oligo-urethane/methacrylate monomer composite materials. A factorial design was used to electrospin four new formulations containing four to five monomers. Synthetic immunomodulatory monomers were crosslinked with GelMa and electrospun with a polycarbonate urethane resulting in unique mechanical properties, and resorption rates which align with the original design criteria for gingival tissue engineering. The materials may have applications in tissue engineering and can be readily manufactured. The findings of this work may help better direct the efforts of tissue engineering and material manufacturing.

An Exosome-Rich Conditioned Medium from Human Amniotic Membrane Stem Cells Facilitates Wound Healing via Increased Reepithelization, Collagen Synthesis, and Angiogenesis

Tissue regeneration is an essential requirement for wound healing and recovery of organs' function. It has been demonstrated that wound healing can be facilitated by activating paracrine signaling mediated by exosomes secreted from stem cells, since exosomes deliver many functional molecules including growth factors (GFs) and neurotrophic factors (NFs) effective for tissue regeneration. In this study, an exosome-rich conditioned medium (ERCM) was collected from human amniotic membrane stem cells (AMSCs) by cultivating the cells under a low oxygen tension (2% O2 and 5% CO2). The contents of GFs and NFs including keratinocyte growth factor, epidermal growth factor, fibroblast growth factor 1, transforming growth factor-β, and vascular endothelial growth factor responsible for skin regeneration were much higher (10-30 folds) in the ERCM than in normal conditioned medium (NCM). In was found that CM-DiI-labeled exosomes readily entered keratinocytes and fibroblasts, and that ERCM not only facilitated the proliferation of keratinocytes in normal condition, but also protected against H2O2 cytotoxicity. In cell-migration assay, the scratch wound in keratinocyte culture dish was rapidly closed by treatment with ERCM. Such wound-healing effects of ERCM were confirmed in a rat whole skin-excision model: i.e., the wound closure was significantly accelerated, remaining minimal crusts, by topical application of ERCM solution (4 × 109 exosome particles/100 μL) at 4-day intervals. In the wounded skin, the deposition of collagens was enhanced by treatment with ERCM, which was supported by the increased production of collagen-1 and collagen-3. In addition, enhanced angiogenesis in ERCM-treated wounds was confirmed by increased von Willebrand factor (vWF)-positive endothelial cells. The results indicate that ERCM from AMSCs with high concentrations of GFs and NFs improves wound healing through tissue regeneration not only by facilitating keratinocyte proliferation for skin repair, but also activating fibroblasts for extracellular matrix production, in addition to the regulation of angiogenesis and scar tissue formation.

Incorporation of collagen into Pseudomonas aeruginosa and Staphylococcus aureus biofilms impedes phagocytosis by neutrophils

Biofilms are communities of microbes embedded in a matrix of extracellular polymeric substances (EPS). Matrix components can be produced by biofilm organisms and can also originate from the environment and then be incorporated into the biofilm. For example, we have recently shown that collagen, a host-produced protein that is abundant in many different infection sites, can be taken up into the biofilm matrix, altering biofilm mechanics. The biofilm matrix protects bacteria from clearance by the immune system, and some of that protection likely arises from the mechanical properties of the biofilm. Pseudomonas aeruginosa and Staphylococcus aureus are common human pathogens notable for forming biofilm infections in anatomical sites rich in collagen. Here, we show that the incorporation of Type I collagen into P. aeruginosa and S. aureus biofilms significantly hinders phagocytosis of biofilm bacteria by human neutrophils. However, enzymatic treatment with collagenase, which breaks down collagen, can partly or entirely negate the protective effect of collagen and restore the ability of neutrophils to engulf biofilm bacteria. From these findings, we suggest that enzymatic degradation of host materials may be a potential way to compromise biofilm infections and enhance the efficacy of the host immune response without promoting antibiotic resistance. Such an approach might be beneficial both in cases where the infecting species is known and also in cases wherein biofilm components are not readily known, such as multispecies infections or infections by unknown species.

One-step generation of core-shell biomimetic microspheres encapsulating double-layer cells using microfluidics for hair regeneration

Tissue engineering of hair follicles (HFs) has enormous potential in the treatment of hair loss. HF morphogenesis is triggered by reciprocal interactions between HF germ epithelial and mesenchymal layers. Here, a microfluidic-assisted technology is developed for the preparation of double aqueous microdroplets that entrap double-layer cells and growth factors to ultimately be used for hair regeneration. Mouse mesenchymal cells (MSCs) and epidermal cells (EPCs) are encapsulated in gelatin methacrylate (GelMA) cores and photo-curable catechol-grafted hyaluronic acid (HAD) shells to fabricate GelMA-MSC/HAD-EPC (G/HAD) microspheres. The findings show that the G/HAD microspheres exhibit ultrafast gelation, aqueous phase separation, superior biocompatibility, and favorable wet adhesion properties. G/HAD microspheres can also support cell proliferation and sustain growth factor release. These composite cell microspheres are capable of efficient HF generation upon transplantation into the dorsal dermis of nude mice. This finding facilitates the large-scale preparation of approximately 80 double-layer cell spheres per min. This simple double-layer cell sphere preparation approach is a promising strategy for improving current hair-regenerative medicine techniques and can potentially be applied along with other organoid techniques for extended applications.

Octenidine Versus Dispase Gels for Wound Healing After Cryosurgery Treatment in Patients with Basal Cell Carcinoma

For a specific group of patients with basal cell carcinoma (small, low risk), cryosurgery could be the suggested treatment, which results in the formation of an ulcer in the lesion area. The proteolytic enzymes' contribution to the wound healing is an ongoing research goal. Preclinical animal experiments in the Laboratory of the Pharmaceutical Technology Department of the National and Kapodistrian University of Athens have showed that a dose of 5 U/mL of dispase gel after the formation of tissue rashes, significantly promoted wound healing. Herein, a feasibility study in 16 patients enrolled by the First Department of Dermatology of Andreas Syggros Hospital was designed: 5 U/mL of dispase gel (once every 3 days) versus a drug reference containing octenidine (daily administration). The evaluation of the healing effect, safety, and tolerance was done on days 1 (cryosurgery), 2, 7, 21, and 60. The study end point was considered either the ulcer complete healing or the eighth week since treatment initiation. Wound healing was faster with dispase gel and hemoglobin reduced rapidly after the seventh day. Yet, hydration was higher in the control group. Our non-parametric analysis provides evidence that the dispase gel shows faster healing compared to the reference drug, in humans, meriting further investigation in larger human sample sizes before massive production of the product.

Robust gelatin hydrogels for local sustained release of bupivacaine following spinal surgery

Adequate treatment of pain arising from spinal surgery is a major clinical challenge. Opioids are the mainstay of current treatment methods, but the frequency and severity of their side effects display a clear need for opioid-free analgesia. Local anesthetics have been encapsulated into sustained-release drug delivery systems to provide postoperative pain relief. However, these formulations are limited by rapid diffusion out of the surgical site. To overcome this limitation, we synthesized ring-shaped hydrogels incorporating bupivacaine, designed to be co-implanted with pedicle screws during spinal surgery. Hydrogels were prepared by riboflavin-mediated crosslinking of gelatin functionalized with tyramine moieties. Additionally, oxidized β-cyclodextrin was introduced into the hydrogel formulation to form dynamic bonds with tyramine functionalities, which enables self-healing behavior and resistance to shear. Feasibility of hydrogel implantation combined with pedicle screws was qualitatively assessed in cadaveric sheep as a model for instrumented spinal surgery. The in-situ crystallization of bupivacaine within the hydrogel matrix provided a moderate burst decrease and sustained release that exceeded 72 hours in vitro. The use of bupivacaine crystals decreased drug-induced cytotoxicity in vitro compared to bupivacaine HCl. Thus, the presented robust hydrogel formulation provides promising properties to enable the stationary release of non-opioid analgesics following spinal surgery. STATEMENT OF SIGNIFICANCE: Currently, postoperative pain following spinal surgery is mainly treated with opioids. However, the use of opioids is associated with several side effects including addiction. Here we developed robust and cytocompatible gelatin hydrogels, prepared via riboflavin-mediated photocrosslinking, that can withstand orthopedic implantation. The implantability was confirmed in cadaveric instrumented spinal surgery. Further, hydrogels were loaded with bupivacaine crystals to provide sustained release beyond 72 hours in vitro. The use of crystallized bupivacaine decreased cytotoxicity compared to bupivacaine HCl. The present formulation can aid in enabling opioid-free analgesia following instrumented spinal surgery.

Applications of Plasma Produced with Electrical Discharges in Gases for Agriculture and Biomedicine

The use of thermal and non-thermal atmospheric pressure plasma to solve problems related to agriculture and biomedicine is the focus of this paper. Plasma in thermal equilibrium is used where heat is required. In agriculture, it is used to treat soil and land contaminated by the products of biomass, plastics, post-hospital and pharmaceutical waste combustion, and also by ecological phenomena that have recently been observed, such as droughts, floods and storms, leading to environmental pollution. In biomedical applications, thermal plasma is used in so-called indirect living tissue treatment. The sources of thermal plasma are arcs, plasma torches and microwave plasma reactors. In turn, atmospheric pressure cold (non-thermal) plasma is applied in agriculture and biomedicine where heat adversely affects technological processes. The thermodynamic imbalance of cold plasma makes it suitable for organic syntheses due its low power requirements and the possibility of conducting chemical reactions in gas at relatively low and close to ambient temperatures. It is also suitable in the treatment of living tissues and sterilisation of medical instruments made of materials that are non-resistant to high temperatures. Non-thermal and non-equilibrium discharges at atmospheric pressure that include dielectric barrier discharges (DBDs) and atmospheric pressure plasma jets (APPJs), as well as gliding arc (GAD), can be the source of cold plasma. This paper presents an overview of agriculture and soil protection problems and biomedical and health protection problems that can be solved with the aid of plasma produced with electrical discharges. In particular, agricultural processes related to water, sewage purification with ozone and with advanced oxidation processes, as well as those related to contaminated soil treatment and pest control, are presented. Among the biomedical applications of cold plasma, its antibacterial activity, wound healing, cancer treatment and dental problems are briefly discussed.

Amnion bilayer for dressing and graft replacement for delayed grafting of full-thickness burns; A study in a rat model

Burn is a common case in developing countries, with over half of fire-related deaths reported in Southeast Asia and full-thickness burns as a high mortality risk. Human amnion has been used as a wound dressing for centuries. In this study, a decellularised amnion overlaid with fibrin, “amnion bilayer (AB),” was used as a dressing immediately after burn and as a graft to replace the scar in Sprague-Dawley rats subjected to full-thickness burn model. The aim was to observe whether amnion bilayer can reduce damages in third-grade burn when skin replacement is deemed impossible. The burn was induced using an electrical solder, heated for 5 mins, and contacted on the rat’s bare skin for 20 s. AB was applied as a (i) dressing immediately after induction and graft after eschar removal. Two groups (n = 6) were compared: AB and Sofra-Tulle ^®, the National Hospital of Indonesia (NHI) protocol. Sections were stained with hematoxylin and eosin and Masson trichrome stains. Immunohistochemistry labelling was used to indicate scars (α-smooth muscle actin [α-SMA] and collagen-1) and angiogenesis (von Willebrand factor). Also, the macrophages inflammatory protein-3α (MIP-3α) indicates an early inflammatory process. The post dressing of the AB group demonstrated hair follicle remains and adipose tissue development. The NHI group appeared with a denatured matrix. Complete healing was seen in the AB group after 28 days with skin appendages similar to normal, while the NHI group showed no appendages in the centre of the actively inflamed area. The α-SMA was found in both groups. Collagen-1 was highly expressed in the NHI group, which led to a scar. Angiogenesis was found more in the AB group. The AB group had shown the capacity to accelerate complete healing and recover skin appendages better than the current protocol.

Skin wound healing assessment via an optimized wound array model in miniature pigs

An appropriate animal wound model is urgently needed to assess wound dressings, cell therapies, and pharmaceutical agents. Minipig was selected owing to similarities with humans in body size, weight, and physiological status. Different wound sizes (0.07-100 cm²) were created at varying distances but fail to adequately distinguish the efficacy of various interventions. We aimed to resolve potential drawbacks by developing a systematic wound healing system. No significant variations in dorsal wound closure and contraction were observed within the thoracolumbar region between boundaries of both armpits and the paravertebral region above rib tips; therefore, Lanyu pigs appear suitable for constructing a reliable dorsal wound array. Blood flow signals interfered with inter-wound distances ˂ 4 cm; a distance > 4 cm is therefore recommended. Wound sizes ≥ 4 cm × 4 cm allowed optimal differentiation of interventions. Partial- (0.23 cm) and full-thickness (0.6 cm) wounds showed complete re-epithelialization on days 13 and 18 and strongest blood flow signals at days 4 and 11, respectively. Given histological and tensile strength assessments, tissue healing resembling normal skin was observed at least after 6 months. We established some golden standards for minimum wound size and distance between adjacent wounds for effectively differentiating interventions in considering 3R principles.

Medical gas plasma-stimulated wound healing: Evidence and mechanisms

Defective wound healing poses a significant burden on patients and healthcare systems. In recent years, a novel reactive oxygen and nitrogen species (ROS/RNS) based therapy has received considerable attention among dermatologists for targeting chronic wounds. The multifaceted ROS/RNS are generated using gas plasma technology, a partially ionized gas operated at body temperature. This review integrates preclinical and clinical evidence into a set of working hypotheses mainly based on redox processes aiding in elucidating the mechanisms of action and optimizing gas plasmas for therapeutic purposes. These hypotheses include increased wound tissue oxygenation and vascularization, amplified apoptosis of senescent cells, redox signaling, and augmented microbial inactivation. Instead of a dominant role of a single effector, it is proposed that all mechanisms act in concert in gas plasma-stimulated healing, rationalizing the use of this technology in therapy-resistant wounds. Finally, addressable current challenges and future concepts are outlined, which may further promote the clinical utilization, efficacy, and safety of gas plasma technology in wound care in the future.

Restoring Endogenous Repair Mechanisms to Heal Chronic Wounds with a Multifunctional Wound Dressing

Current treatment of chronic wounds has been critically limited by various factors, including bacterial infection, biofilm formation, impaired angiogenesis, and prolonged inflammation. Addressing these challenges, we developed a multifunctional wound dressing-based three-pronged approach for accelerating wound healing. The multifunctional wound dressing, composed of nanofibers, functional nanoparticles, natural biopolymers, and selected protein and peptide, can target multiple endogenous repair mechanisms and represents a promising alternative to current wound healing products.

Photo-crosslinkable amniotic membrane hydrogel for skin defect healing

The human amniotic membrane (HAM) collagen matrix derived from human placenta can be decellularized (dHAM) to form a natural biocompatible material. dHAM has different bioactive substances and has been used widely in human tissue engineering research. However, dHAM has some disadvantages, e.g., poor mechanical properties, easy degradation and inconvenient operation and use, so it is not conducive to large-area or full-thickness skin defect healing. To overcome these limitations, for the first time, dHAM was grafted with methacrylic anhydride (MA) to form photocrosslinked dHAM methacrylate (dHAMMA); dHAMMA was then blended with methacrylated gelatin (GelMA), followed by the addition of a photosensitizer for photocrosslinking to obtain the fast-forming GelMA-dHAMMA composite hydrogel. Further, GelMA-dHAMMA was found to have the porous structure of a bicomponent polymer network and good physical and chemical properties. In vitro experiments, GelMA-dHAMMA was found to promote fibroblast proliferation and α-smooth muscle actin (α-SMA) expression. In vivo investigations also demonstrated that GelMA-dHAMMA promotes wound collagen deposition and angiogenesis, and accelerates tissue healing. GelMA-dHAMMA inherits the good mechanical properties of GelMA and maintains the biological activity of the amniotic membrane, promoting the reconstruction and regeneration of skin wounds. Thus, GelMA-dHAMMA can serve as a promising biomaterial in skin tissue engineering. STATEMENT OF SIGNIFICANCE: Since the early 20th century, the human amniotic membrane (HAM) has been successfully used for trauma treatment and reconstruction purposes. dHAM has different bioactive substances and has been used widely in human tissue-engineering research. In this work, the dHAM and gelatin were grafted and modified by using methacrylic anhydride (MA) to form photocrosslinked dHAMMA and methacrylated gelatin (GelMA). Then, the dHAMMA and GelMA were blended with a photosensitizer to form the GelMA-dHAMMA composite hydrogel derived from gelatin-dHAM. GelMA-dHAMMA exhibits a bicomponent-network (BCN) interpenetrating structure. dHAM dydrogel has advantages, e.g., good mechanical properties, slow degradation and convenient operation, so it is conducive to large-area or full-thickness skin defect healing.

Structure-guided protein engineering of human cathepsin L for efficient collagenolytic activity

Engineering precise substrate specificity of proteases advances the potential to use them in biotechnological and therapeutic applications. Collagen degradation, a physiological process mediated by collagenases, is an integral part of extracellular matrix remodeling and when uncontrolled, implicated in different pathological conditions. Lysosomal cathepsin-K cleaves triple helical collagen fiber, whereas cathepsin-L cannot do so. In this study, we have imparted collagenolytic property to cathepsin-L, by systematically engineering proline-specificity and glycosaminoglycans (GAG)-binding surface in the protease. The proline-specific mutant shows high specificity for prolyl-peptidic substrate but is incapable of cleaving collagen. Engineering a GAG-binding surface on the proline-specific mutant enabled it to degrade type-I collagen in the presence of chondroitin-4-sulfate (C4-S). We also present the crystal structures of proline-specific (1.4 Å) and collagen-specific (1.8 Å) mutants. Finally docking studies with prolyl-peptidic substrate (Ala-Gly-Pro-Arg-Ala) at the active site and a C4-S molecule at the GAG-binding site enable us to identify key structural features responsible for collagenolytic activity of cysteine cathepsins.

[Suitability of biological acellular dermal matrices as a skin replacement]

INTRODUCTION

 Tissue defects are associated with loss of epidermal and dermal components of the skin. For full-thickness tissue defects, dermal equivalents are useful to enable rapid wound closure. Split-thickness skin grafts are associated with loss of tissue elasticity resulting in scar contractures that can impair joint mobility. Synthetic collagen matrices and allogeneic acellular dermal matrices (ADM) are commercially available and could serve as skin tissue replacement. The aim of this study was to investigate whether ADM of different dermal layers or bioartificial matrices can serve as cutaneous replacement. For this purpose, cellular migration, differentiation and the inflammatory reaction were studied in an established ex vivo skin organ model.

MATERIALS AND METHODS

 Human split-thickness skin grafts were transplanted onto ADM (Epiflex, DIZG, Berlin, Germany), de-epidermized dermis (DED) or an artificial collagen-elastin matrix (Matriderm, Dr. Suwelack, Billerbeck, Germany). Epithelial migration was studied using an established skin culture model at the air-liquid interface. In addition, the effect of tissue from different dermal compartments, e. g. papillar and reticular dermis, on epithelial migration was compared. Epithelial resurfacing and differentiation of matrices as well as the inflammatory reaction were studied using histological, immunohistochemical and biochemical analyses.

RESULTS AND CONCLUSION

 Significantly more epithelial outgrowth area was found on DED (2.54 mm ± 0.43 mm, mean ± SEM) compared to papillary ADM (1.32 mm ± 0.44 mm, p = 0.039), to reticular ADM (no horizontal growth, p < 0.0001) and collagen-elastin matrix (0.78 mm ± 0.11 mm, p = 0.0056) measured by fluorescence microscopy over 10 days presumably due to the presence of pro-migratory basement membrane residues on DED. Reepithelialization was significantly higher (p < 0.002) on papillary dermis compared to ADM of reticular origin. In contrast to the biological matrices, a complete horizontal penetration was found in the macroporous collagen-elastin matrix. Pro-inflammatory mediators varied depending on the human skin donor and matrix. In summary, the biochemical structure of the matrix' surface and its origin influenced the epithelial behaviour with regard to migration, differentiation and inflammatory response.

The zone model: A conceptual model for understanding the microenvironment of chronic wound infection

In 2008, two articles in Wound Repair and Regeneration changed the clinical perspective on chronic wounds. They stated that chronic wounds that do not heal contain bacterial biofilms and that these biofilms may be one of the reasons for the nonhealing properties of the wounds. However, we still do not understand the exact role biofilms play in the halted healing process, and we are not able to successfully treat them. The reason for this could be that in vivo biofilms differ substantially from in vitro biofilms, and that most of the knowledge about biofilms originates from in vitro research. In this article, we introduce the zone model as a concept for understanding bacterial behavior and the impact of the microenvironment on both the host and the bacteria. Until now, identification of bacteria, gene expression, and postscript regulation have been looking at a bulk of bacteria and averaging the behavior of all the bacteria. As the zone model dictates that every single bacterium reacts to its own microenvironment, the model may facilitate the planning of future research with improved clinical relevance. The zone model integrates physiology and biology from single cells, microbial aggregates, local host response, surrounding tissue, and the systemic context of the whole host. Understanding the mechanisms behind the actions and reactions by a single bacterium when interacting with other neighboring bacteria cells, other microorganisms, and the host will help us overcome the detrimental effects of bacteria in chronic wounds. Furthermore, we propose use of the terminology "bacterial phenotype" when describing the actions and reactions of bacteria, and the term "biofilms" to describe the morphology of the bacterial community.

Evaluation of decellularized tilapia skin as a tissue engineering scaffold

Decellularized bovine and porcine tissues have been used as scaffolds to support tissue regeneration but inherit religious restrictions and risks of disease transmission to humans. Decellularized marine tissues are seen as attractive alternatives due to their similarity to mammalian tissues, reduced biological risks, and less religious restrictions. The aim of this study was to derive an acellular scaffold from the skin of tilapia and evaluate its suitability as a tissue engineering scaffold. Tilapia skin was treated with a series of chemical and enzymatic treatments to remove cellular materials. The decellularized tilapia skin (DTS) was then characterized and evaluated in vitro and in vivo to assess its biological compatibility. The results indicated that the decellularization process removed 99.6% of the DNA content from tilapia skin. The resultant DTS was shown to possess a high denaturation temperature of 68.1 ± 1.0°C and a high Young's modulus of 56.2 ± 14.4 MPa. The properties of DTS were also compared against those of crosslinked electrospun tilapia collagen membrane, another form of tilapia-derived collagen scaffold. In vitro studies revealed that both DTS and crosslinked electrospun tilapia collagen promoted cellular metabolic activity, differentiation, and mineralization of murine preosteogenic MC3T3-E1 cells. The rat calvarial defect model was used to evaluate the in vivo performance of the scaffolds, and both scaffolds did not induce hyperacute rejections. Furthermore, they enhanced bone regeneration in the critical defect compared with the sham control. This study suggests that tilapia-derived scaffolds have great potential in tissue engineering applications.

Cell-instructive pectin hydrogels crosslinked via thiol-norbornene photo-click chemistry for skin tissue engineering

Cell-instructive hydrogels are attractive for skin repair and regeneration, serving as interactive matrices to promote cell adhesion, cell-driven remodeling and de novo deposition of extracellular matrix components. This paper describes the synthesis and photocrosslinking of cell-instructive pectin hydrogels using cell-degradable peptide crosslinkers and integrin-specific adhesive ligands. Protease-degradable hydrogels obtained by photoinitiated thiol-norbornene click chemistry are rapidly formed in the presence of dermal fibroblasts, exhibit tunable properties and are capable of modulating the behavior of embedded cells, including the cell spreading, hydrogel contraction and secretion of matrix metalloproteases. Keratinocytes seeded on top of fibroblast-loaded hydrogels are able to adhere and form a compact and dense layer of epidermis, mimicking the architecture of the native skin. Thiol-ene photocrosslinkable pectin hydrogels support the in vitro formation of full-thickness skin and are thus a highly promising platform for skin tissue engineering applications, including wound healing and in vitro testing models.

STATEMENT OF SIGNIFICANCE

Photopolymerizable hydrogels are attractive for skin applications due to their unique spatiotemporal control over the hydrogel formation. This study reports the design of a promising photo-clickable pectin hydrogel which biophysical and biochemical properties can be independently tailored to control cell behavior. A fast method for the norbornene-functionalization of pectin was developed and hydrogels fabricated through UV photoinitiated thiol-norbornene chemistry. This one-pot click reaction was performed in the presence of cells using cell-adhesive and matrix metalloproteinase-sensitive peptides, yielding hydrogels that support extensive cell spreading. Keratinocytes seeded on top of the fibroblast-loaded hydrogel formed a compact epidermis with morphological resemblance to human skin. This work presents a new protease-degradable hydrogel that supports in vitro skin formation with potential for skin tissue engineering.

Matrix metalloproteinases: The sculptors of chronic cutaneous wounds

Cutaneous wound healing is a complex mechanism with multiple processes orchestrating harmoniously for structural and functional restoration of the damaged tissue. Chronic non-healing wounds plagued with infection create a major healthcare burden and is one of the most frustrating clinical problems. Chronic wounds are manifested by prolonged inflammation, defective re-epithelialization and haphazard remodeling. Matrix metalloproteinases (MMPs) are zinc dependent enzymes that play cardinal functions in wound healing. Understanding the pathological events mediated by MMPs during wound healing may pave way in identifying novel drug targets for chronic wounds. Here, we discuss the functions and skewed regulation of different MMPs during infection and chronic tissue repair. This review also points out the potential of MMPs and their inhibitors as therapeutic agents in treating chronic wounds during distinct phases of the wound healing. This article is part of a Special Issue entitled: Proteolysis as a Regulatory Event in Pathophysiology edited by Stefan Rose-John.

Collagenolytic enzymes produced by fungi: a systematic review

Specific proteases capable of degrading native triple helical or denatured collagen have been required for many years and have a large spectrum of applications. There are few complete reports that fully uncover production, characterization and purification of fungi collagenases. In this review, authors searched through four scientific on line data bases using the following keywords (collagenolytic OR collagenase) AND (fungi OR fungus OR fungal) AND (production OR synthesis OR synthesize) AND (characterization). Scientific criteria were adopted in this review to classify found articles by score (from 0 to 10). After exclusion criteria, 21 articles were selected. None obtained the maximum of 10 points defined by the methodology, which indicates a deficiency in studies dealing simultaneously with production, characterization and purification of collagenase by fungi. Among microorganisms studied the non-pathogenic fungi Penicillium aurantiogriseum and Rhizoctonia solani stood out in volumetric and specific collagenase activity. The only article found that made sequencing of a true collagenase showed 100% homology with several metalloproteinases fungi. A clear gap in literature about collagenase production by fungi was verified, which prevents further development in the area and increases the need for further studies, particularly full characterization of fungal collagenases with high specificity to collagen.

Cytokine and Growth Factor mRNA Expression Patterns Associated with the Hypercontracted, Hyperpigmented Healing Phenotype of Red Duroc Pigs: A Model of Abnormal Human Scar Development?

Background:

Skin wounds in red Duroc pigs heal with the formation of hypercontractile, hyperpigmented scars, similar in some respects to human hypertrophic scars. ObjectiveThe goal of this study was to characterize the mRNA expression patterns for a subset of relevant cytokines, growth factors, receptors, and transcription factors involved in the red Duroc scarring phenotype.

Methods:

Full-thickness and deep dermal wounds were created on the backs of juvenile female red Duroc pigs. Samples were taken every two weeks postwounding and total RNA and DNA were extracted and quantified. RT-PCR was performed using porcine gene-specific primers for 15 relevant molecules.

Results:

The majority of molecules examined exhibited a biphasic pattern of expression, with peaks of expression at days 14 and 56 postinjury.

Conclusions:

The molecular expression pattern observed correlates well with the gross healing phenotype and matrix molecule expression patterns previously reported in red Duroc pigs. These findings enhance our understanding of the processes associated with fibroproliferative scar-formation.

Complementary Proteomic and Biochemical Analysis of Peptidases in Lobster Gastric Juice Uncovers the Functional Role of Individual Enzymes in Food Digestion

Crustaceans are a diverse group, distributed in widely variable environmental conditions for which they show an equally extensive range of biochemical adaptations. Some digestive enzymes have been studied by purification/characterization approaches. However, global analysis is crucial to understand how digestive enzymes interplay. Here, we present the first proteomic analysis of the digestive fluid from a crustacean (Homarus americanus) and identify glycosidases and peptidases as the most abundant classes of hydrolytic enzymes. The digestion pathway of complex carbohydrates was predicted by comparing the lobster enzymes to similar enzymes from other crustaceans. A novel and unbiased substrate profiling approach was used to uncover the global proteolytic specificity of gastric juice and determine the contribution of cysteine and aspartic acid peptidases. These enzymes were separated by gel electrophoresis and their individual substrate specificities uncovered from the resulting gel bands. This new technique is called zymoMSP. Each cysteine peptidase cleaves a set of unique peptide bonds and the S2 pocket determines their substrate specificity. Finally, affinity chromatography was used to enrich for a digestive cathepsin D1 to compare its substrate specificity and cold-adapted enzymatic properties to mammalian enzymes. We conclude that the H. americanus digestive peptidases may have useful therapeutic applications, due to their cold-adaptation properties and ability to hydrolyze collagen.

Photocrosslinkable Gelatin Hydrogel for Epidermal Tissue Engineering

Natural hydrogels are promising scaffolds to engineer epidermis. Currently, natural hydrogels used to support epidermal regeneration are mainly collagen- or gelatin-based, which mimic the natural dermal extracellular matrix but often suffer from insufficient and uncontrollable mechanical and degradation properties. In this study, a photocrosslinkable gelatin (i.e., gelatin methacrylamide (GelMA)) with tunable mechanical, degradation, and biological properties is used to engineer the epidermis for skin tissue engineering applications. The results reveal that the mechanical and degradation properties of the developed hydrogels can be readily modified by varying the hydrogel concentration, with elastic and compressive moduli tuned from a few kPa to a few hundred kPa, and the degradation times varied from a few days to several months. Additionally, hydrogels of all concentrations displayed excellent cell viability (>90%) with increasing cell adhesion and proliferation corresponding to increases in hydrogel concentrations. Furthermore, the hydrogels are found to support keratinocyte growth, differentiation, and stratification into a reconstructed multilayered epidermis with adequate barrier functions. The robust and tunable properties of GelMA hydrogels suggest that the keratinocyte laden hydrogels can be used as epidermal substitutes, wound dressings, or substrates to construct various in vitro skin models.

Radiation cross-linked collagen/dextran dermal scaffolds: effects of dextran on cross-linking and degradation

Ionizing radiation effectively cross-links collagen into network with enhanced anti-degradability and biocompatibility, while radiation-cross-linked collagen scaffold lacks flexibility, satisfactory surface appearance, and performs poor in cell penetration and ingrowth. To make the radiation-cross-linked collagen scaffold to serve as an ideal artificial dermis, dextran was incorporated into collagen. Scaffolds with the collagen/dextran (Col/Dex) ratios of 10/0, 7/3, and 5/5 were fabricated via (60)Co γ-irradiation cross-linking, followed by lyophilization. The morphology, microstructure, physicochemical, and biological properties were investigated. Compared with pure collagen, scaffolds with dextran demonstrated more porous appearance, enhanced hydrophilicity while the cross-linking density was lower with the consequence of larger pore size, higher water uptake, as well as reduced stiffness. Accelerated degradation was observed when dextran was incorporated in both the in vitro and in vivo assays, which led to earlier integration with cell and host tissue. The effect of dextran on degradation was ascribed to the decreased cross-linking density, looser microstructure, more porous and hydrophilic surface. Considering the better appearance, softness, moderate degradation rate due to controllable cross-linking degree and good biocompatibility as well, radiation-cross-linked collagen/dextran scaffolds are expected to serve as promising artificial dermal substitutes.

Enzymatic, antimicrobial and toxicity studies of the aqueous extract of Ananas comosus (pineapple) crown leaf

ETHNOPHARMACOLOGICAL RELEVANCE

Various parts of the plant pineapple (Ananas comosus) are used in traditional medicine worldwide for treatment of a number of diseases and disorders. In folk medicine, pineapple leaf extract was used as an antimicrobial, vermicide, purgative, emmenagoogue, abortifacient, anti-oedema and anti-inflammatory agent. Compared to the fruit and stem extracts of pineapple, information about its leaf extract is limited. The potential of pineapple crown leaf extract as an ethno-medicine has been evaluated in terms of its enzymatic activities related to wound healing, antimicrobial property and toxicity.

MATERIALS AND METHODS

Major protein components of the extract were revealed by 2-D gel electrophoresis followed by MS/MS analysis. Zymography, DQ-gelatin assay were performed to demonstrate proteolytic, fibrinolytic, gelatinase and collagenase activities. DNase and RNase activities were revealed from agarose gel electrophoresis. Antimicrobial activity was evaluated spectrophotometrically from growth inhibition. Sprague-Dawley rat model was used to measure acute and sub-acute toxicity of the extract by analyzing blood markers.

RESULT

The extract contains several proteins that were clustered under native condition. Proteomic studies indicated presence of fruit bromelain as major protein constituent of the extract. It showed nonspecific protease activity, gelatinolytic, collagenase, fibrinolytic, acid and alkaline phosphatase, peroxidase, DNase and RNase activities along with considerable anti-microbial property. The leaf extract did not induce any toxicity in rats after oral administration of acute and sub-acute doses.

CONCLUSION

Pineapple leaf extract is nontoxic, contains enzymes related to damage tissue repairing, wound healing and possibly prevents secondary infections from microbial organisms.

The cervical mucus plug inhibits, but does not block, the passage of ascending bacteria from the vagina during pregnancy

OBJECTIVE

To evaluate the microbial load and the inflammatory response in the distal and proximal parts of the cervical mucus plug.

DESIGN

Experimental research.

POPULATION

Twenty women with a normal, singleton pregnancy.

SAMPLE

Vaginal swabs and specimens from the distal and proximal parts of the cervical mucus plug.

METHODS

Immunohistochemistry, enzyme-linked immunosorbent assay, quantitative polymerase chain reaction and histology.

RESULTS

The total bacterial load (16S rDNA) was significantly lower in the cervical mucus plug compared with the vagina (p = 0.001). Among women harboring Ureaplasma parvum, the median genome equivalents/g were 1574 (interquartile range 2526) in the proximal part, 657 (interquartile range 1620) in the distal part and 60,240 (interquartile range 96,386) in the vagina. Histological examinations and quantitative polymerase chain reaction revealed considerable amounts of lactobacilli and inflammatory cells in both parts of the cervical mucus plug. The matrix metalloproteinase-8 concentration was decreased in the proximal part of the plug compared with the distal part (p = 0.08).

CONCLUSION

The cervical mucus plug inhibits, but does not block, the passage of Ureaplasma parvum during its ascending route from the vagina through the cervical canal.

Scab-inspired cytophilic membrane of anisotropic nanofibers for rapid wound healing

This work investigates the influence of cytophilic and anisotropic nanomaterials on accelerated cell attachment and directional migration toward rapid wound healing. Inspired by the anisotropic protein nanofibers in scab, a polyurethane (PU) nanofibrous membrane with an aligned structure was fabricated. The membrane showed good affinity for wound-healing-related cells and could guide cell migration in the direction of PU nanofibers. Also, the morphology and distribution of F-actin and paxillin of attached cells were influenced by the underlying nanofibers. The randomly distributed PU nanofibers and planar PU membrane did not show a distinct impact on cell migration. This scab-inspired cytophilic membrane is promising in applications as functional interfacial biomaterials for rapid wound healing, bone repair, and construction of neural networks.

Characterization of the aqueous extract of the root of Aristolochia indica: evaluation of its traditional use as an antidote for snake bites

ETHNOPHARMACOLOGICAL RELEVANCE

The aqueous extract of the roots of Aristolochia indica is used as a decoction for the ailment of a number of diseases including snake bite treatment. Though the alcoholic extract of the different parts of the plant are well studied, information on the aqueous extract is limited. We have estimated aristolochic acid, different enzymes, enzyme inhibitors and anti-snake venom potency of its root extract.

MATERIALS AND METHODS

Reverse phase-HPLC was used to quantify aristolochic acid. Zymography, DQ-gelatin assay and atomic force microscopy were done to demonstrate gelatinase and collagenase activities of the extract. SDS-PAGE followed by MS/MS analysis revealed the identity of major protein components. Toxicity of the extract was estimated on animal model. Interaction of the extract with Russell's viper venom components was followed by Rayleigh scattering and enzyme assay.

RESULTS

The aristolochic acid content of the root extract is 3.08 ± 1.88 × 10(-3)mg/ml. The extract possesses strong gelatinolytic, collagenase, peroxidase and nuclease activities together with l-amino acid oxidase and protease inhibitory potencies. Partial proteomic studies indicated presence of starch branching enzymes as major protein constituent of the extract. The extract did not show any acute and sub-chronic toxicity in animals at lower doses, but high dose causes liver and kidney damage. The extract elongated duration of survival of animals after application of Russell's viper venom.

CONCLUSIONS

Considering the low aristolochic acid content of the extract, its consumption for a short time at moderate dose does not appear to cause serious toxicity. Strong inhibition of l-amino acid oxidase may give partial relief from snake bite after topical application of the extract.

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.

Anthocyanins from black soybean seed coats stimulate wound healing in fibroblasts and keratinocytes and prevent inflammation in endothelial cells

Wound healing is a complex process that includes inflammation, tissue formation, and remodeling. While wound healing is accompanied by inflammatory reactions, chronic inflammation impairs acute wound healing. In this study, we investigated whether anthocyanins from black soybean seed coats could stimulate wound healing while preventing excessive inflammation. At 24h of treatment with anthocyanins, fibroblasts showed a significant increase in migration at 100 microg/mL whereas the migration of keratinocytes increased significantly at 50 and 100 microg/mL compared to control. Treatment of anthocyanins for 48 h significantly stimulated the migration of both human dermal fibroblasts and keratinocytes at 50 and 100 microg/mL concentrations. Treatment of cells with anthocyanins stimulated wound-induced VEGF production in fibroblasts and keratinocytes. However, anthocyanins inhibited ROS accumulation and VEGF production in TNF-alpha-stimulated endothelial cells. Furthermore, treatment of anthocyanins reduced, in a dose-dependent manner, the adhesion of inflammatory monocytes to endothelial cells. Anthocyanins also blocked both the translocation of nuclear factor-kappa B (NF-kappaB) p65 into the nucleus and the phosphorylation of the inhibitory factor kappaBalpha (IkappaBalpha). Thus, treatment with anthocyanins from black soybean seed coats may be a potential therapeutic strategy to promote wound healing and to prevent inflammation in a persistent inflammatory condition.

Matrix Gene Expression in Dermal Fibroblasts Cultured on Hyaluronan-coated Polysulfone Membranes

Polysulfone (PSU) membranes, coated and uncoated hyaluronan (HA), were compared for their ability to allow dermal fibroblast express genes related to extracellular matrix synthesis and remodeling. Fibroblasts type I and type III collagens were studied on both types of membranes; only type I collagen was synthesized on control cultures in plastic Petri dishes, whereas type III collagen was also expressed on PSU membranes. Expression of metalloproteinase (MMP)1, MMP3, and MMP2 was enhanced on PSU and HA-coated PSU membranes, with a lower level of MMP2 on HA-covered membranes. These membranes promote fetal-like matrices that provide good support for skin wound healing as well as favor nonscarring tissue repair.

Cytokine and Growth Factor mRNA Expression Patterns Associated with the Hypercontracted, Hyperpigmented Healing Phenotype of Red Duroc Pigs: A Model of Abnormal Human Scar Development?

BACKGROUND

Skin wounds in red Duroc pigs heal with the formation of hypercontractile, hyperpigmented scars, similar in some respects to human hypertrophic scars.

OBJECTIVE

The goal of this study was to characterize the mRNA expression patterns for a subset of relevant cytokines, growth factors, receptors, and transcription factors involved in the red Duroc scarring phenotype.

METHODS

Full-thickness and deep dermal wounds were created on the backs of juvenile female red Duroc pigs. Samples were taken every two weeks postwounding and total RNA and DNA were extracted and quantified. RT-PCR was performed using porcine gene-specific primers for 15 relevant molecules.

RESULTS

The majority of molecules examined exhibited a biphasic pattern of expression, with peaks of expression at days 14 and 56 postinjury.

CONCLUSIONS

The molecular expression pattern observed correlates well with the gross healing phenotype and matrix molecule expression patterns previously reported in red Duroc pigs. These findings enhance our understanding of the processes associated with fibroproliferative scar-formation.

Nitrosoglutathione triggers collagen deposition in cutaneous wound repair

The presence of nitric oxide (NO) is associated with enhanced wound fibroblast collagen synthesis; previous observations have focused on the effect of NO on wound collagen content. This article emphasizes the effect of nitrosothiols on wound collagen deposition and matrix-metalloproteinase activity, which is the primary breakdown pathway of collagen. We examined the effects of S-nitrosoglutathione (GSNO) and glutathione (GSH) on rat scar tissue. Hydroxyproline content, matrix metalloproteinase activity, total glutathione, and total nitrite of scar tissue were measured 3, 5, 7, and 10 days after wounding. It was observed that, at Day 5 and Day 10, wound collagen content was 52.0 percent and 47.5 percent higher, respectively, after GSNO administration than in controls (p<0.05). GSH administration decreased wound collagen deposition 76.5 percent by Day 5 (p<0.05). GSH lowered the matrix metalloproteinase activity 67 percent at Day 5 and 50 percent (p<0.05) at Day 10. Nitrite and nitrate levels were 55 percent higher in the GSNO treated rats than in the control group (p<0.05) at Day 3, whereas the GSH-treated groups showed no changes. GSNO increased systemic nitrite 53 percent 3 hours after intraperitoneal injection. Our findings suggest that collagen deposition increases in cutaneous wound healing after the administration of GSNO and that this nitrosothiol does not interfere with the collagenolytic pathway, thus maintaining the physiological conditions necessary for wound healing.

TIMP-1 antisense gene transfection attenuates the invasive potential of pancreatic cancer cells in vitro and inhibits tumor growth in vivo

BACKGROUND

TIMP-1 overexpression decreases the invasive potential of pancreatic cancer cells. By tissue inhibitors of metalloproteinase (TIMP)-1 antisense gene transfection, we expected to produce aggressive pancreatic cancer cells with increased in vitro and in vivo invasive potential.

METHODS

PANC-1 cells were transfected with either TIMP-1 gene (CD-1), antisense TIMP-1 gene (AS-3), or empty vector (MB-3). The in vitro cell growth kinetics and invasive potential of each cell line were compared. Total and active matrix metalloproteinase (MMP)-2 levels were determined. Each cell line was then implanted in athymic mice and the resultant tumors were compared for size, weight, MMP activity, and TIMP-1 expression.

RESULTS

TIMP-1 modulation did not affect cell proliferation in vitro, but its underexpression and, to a lesser extent, overexpression resulted in attenuated tumor growth in vivo. AS-3 cells showed marked decreases in cell invasion and MMP-2 activity in vitro and in vivo.

CONCLUSION

TIMP-1 manipulation, particularly underexpression, greatly reduces the invasive potential of pancreatic cancer by limiting MMP-2 activity without affecting in vitro cell growth. TIMP-1 is a reasonable molecular target in pancreatic cancer therapy.

Matrix metalloproteinase inhibitor GM 6001 attenuates keratinocyte migration, contraction and myofibroblast formation in skin wounds

In this study, we examined the impact of matrix metalloproteinases (MMP) on epithelialization, granulation tissue development, wound contraction, and alpha-smooth muscle actin (ASMA) expression during cutaneous wound repair through systemic administration of the synthetic broad-spectrum MMP inhibitor GM 6001 (N-[(2R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl]-L-tryptophan methylamide). Four full-thickness excisional wounds (50 mm2) on the back of 22 young female Sprague-Dawley rats, 12 treated with GM 6001 100 mg/kg and 10 with vehicle, were allowed to heal by secondary intention. GM 6001-treated wounds were minimally resurfaced with neoepithelium, despite unaltered keratinocyte proliferation in wound edges, whereas control wounds were completely covered with 3-7 cell layers of parakeratinized epithelium on post-wounding day 7. Hydroxyproline concentration, a marker of collagen, and cell proliferation in granulation tissue did not differ significantly between GM 6001-treated and control groups. Impaired wound contraction (P < 0.01) was associated with a dramatic reduction of ASMA-positive myofibroblasts in granulation tissue of GM 6001 wounds. This was not due to GM6001 blocking transforming growth factor-beta1 (TGF-beta1)-induced myofibroblast differentiation since GM 6001 did not inhibit TGF-beta1-induced ASMA expression and force generation in cultured rat dermal fibroblasts. The profound impairment of skin repair by the nonselective MMP inhibitor GM 6001 suggests that keratinocyte resurfacing, wound contraction, and granulation tissue organization are highly MMP-dependent processes.