Miguel Concha

Nanoparticles for the Treatment of Wounds

The treatment of skin wounds represents an important research area due to the important physiological and aesthetic role of this tissue. During the last years, nanoparticles have emerged as important platforms to treat skin wounds. Silver, gold, and copper nanoparticles, as well as titanium and zinc oxide nanoparticles, have shown potential therapeutic effects on wound healing. Due to their specific characteristics, nanoparticles such as nanocapsules, polymersomes, solid lipid nanoparticles, and polymeric nanocomplexes are ideal vehicles to improve the effect of drugs (antibiotics, growth factors, etc.) aimed at wound healing. On the other hand, if active excipients are added during the formulation, such as hyaluronate or chitosan, the nanomedicine could significantly improve its potential. In addition, the inclusion of nanoparticles in different pharmaceutical materials may enhance the beneficial effects of the formulations, and allow achieving a better dose control. This paper aims at reviewing significant findings in the area of nanoparticles and wound treatment. Among the reviewed topics, we underline formulations comprising inorganic, polymeric, surfactant self-assembled, and lipid nanosystems. Among the drugs included in the nanoformulations, the paper refers to antibiotics, natural extracts, proteins, and growth factors, among others. Finally, the paper also addresses nanoparticles embedded in secondary vehicles (fibers, dressings, hydrogels, etc.) that could improve their application and/or upgrade the release profile of the active.

Glass Wool Filtration Reduces Reactive Oxygen Species by Elimination of Leukocytes in Oligozoospermic Patients with Leukocytospermia

AbstractPurpose: Two types of glass wool were used to remove leukocytes in semen for evaluation of reactive oxygen species production by spermatozoa in oligozoospermic patients with leukocytospermia. Methods: Semen samples were prepared using fine-structure glass wool (SpermFertil) and coarse-structure glass wool. In each treatment group, native semen was evaluated for sperm concentration, percentage motility, viability, leukocyte concentration, and production of reactive oxygen species. Results: Electron microscopically, SpermFertil showed a higher number of leukocytes attached to the fibers compared to coarse-structure glass wool. Leukocytes in native semen and after glass wool filtration as determined by peroxidase cytochemistry confirmed this observation. Reactive oxygen species decreased from 45.303 counts/107 viable cells in native semen to 15.806 counts/107 cells in coarse structure wool and 7.465 counts/107 cells in Spermfertil, respectively. Conclusions: Removal of leukocytes from semen of oligozoospermic patients by means of glass wool filtration is a useful method to distinguish production of reactive oxygen species by leukocytes versus sperm cells.

Effects of CD40 ligation on human keratinocyte accessory function.

Abstract CD40/CD40 ligand interactions are known to play a key role in the development of immune reactions, especially by enhancing the costimulatory function of professional antigen-presenting cells (APC). Little is known, however, about the role this receptor plays on occasional APC, i.e. cells that are induced to express MHC class II molecules following an inflammatory process. In this study, we used CD40 ligand-transfected cells to analyze the effect of CD40 ligation on the phenotype, as well as accessory function, of human keratinocytes. We found that CD40 ligation enhanced ICAM-1 expression and did not upregulate HLA-DR, CD80 or CD86 expression on IFN-γ-treated keratinocytes. CD40 triggering was not sufficient to generate primary allogeneic T-cell responses even in the presence of anti-CD28 monoclonal antibody (mAb). Moreover, CD40 ligation, in the presence or not of IFN-γ, did not alter the accessory function of keratinocytes in PHA- or superantigen-induced T-cell activation. The lack of effect on the T-cell response was confirmed in blocking experiments using anti-CD40 mAbs. Collectively, these results suggest that CD40-CD40 ligand interactions on nonprofessional APC may amplify the inflammatory reaction without providing a mitogenic signal to the T cells.

Therapeutic potential of a low-cost device for wound healing: a study of three cases of healing after lower-extremity amputation in patients with diabetes.

Diabetic foot ulcers constitute a tremendous challenge for patients, caregivers, and health care systems. The high incidence and high financial costs associated with their treatment have transformed them in a health and economic worldwide problem. The increase in population life expectancy and lifestyle changes have facilitated the spreading of diabetes, rising diabetic foot ulcer incidence. Only 60%–80% of the patients achieve healing of ulcers, and the incidence of a second ulcer, in the same or different site of the foot that has had a previous ulcer, is approximately 50% in 2–5 years. In addition, ulcers with duration longer than 4 weeks are commonly associated with bad results in healing and an increased risk of amputation. Three patients with type 2 diabetes mellitus have been subjected to treatment with NL.1.2, a low-cost, biocompatible solid device that presented pro-angiogenic properties. The selected patients had undergone amputation, and their wounds, classified as Wagner II, did not show a significant progress in healing after a period of 2–5 months before treatment with NL.1.2. Complete closure of their wounds was achieved in 42–60 days.

Chapter 25: Gap Junctions in Inflammatory Responses: Connexins, Regulation and Possible Functional Roles

Publisher Summary The properties of the inflammatory response depend on the quality, intensity, and duration of the insult (e.g., microorganism, foreign molecule, trauma, burn, and infarct), as well as on the individual and the affected tissue. Moreover, an inflammatory process could be acute or chronic and it is mediated chiefly by the innate or the specific immune system. The main components of innate immunity are physical and chemical barriers (e.g., epithelia and antimicrobial substances), blood proteins (e.g., complement factors), phagocytic cells (e.g., neutrophils and macrophages), and other leukocytes (e.g., natural killer cells). On the other hand, the principal components of the specific immunity are humoral (antibodies) and cellular (CD4+T cells). The specific immune response amplifies the mechanism of innate immunity and enhances their function, particularly upon repeated exposures to the same foreign antigen. Inflammation is a progressive process that shows overlapping phases. Whereas the acute unspecific response is characterized by hernodynamic, metabolic, and cellular changes, the specific response begins with the recognition of the antigen by specific lymphocytes, followed by their proliferation and differentiation into effector cells.

Intracellular signaling pathways involved in the release of IL-4 and VEGF from human keratinocytes by activation of kinin B1 receptor: functional relevance to angiogenesis

The injured skin produces a number of mediators that directly or indirectly modulate cell chemotaxis, migration, proliferation, and angiogenesis. Components of the kinin pathway including the kinin B1 receptor (B1R) have been found to occur in the human skin, but information about its role on keratinocyte biology is still scarce. Our aim was to determine whether stimulation of B1R causes the secretion of IL-4 and/or VEGF from human keratinocytes and to evaluate the role of the B1R agonist Lys-des[Arg9]bradykinin and IL-4 on various stages of angiogenesis, such as cell migration, proliferation, and release of metalloproteases. By using ELISA and Western blotting, we showed that HaCaT keratinocytes stimulated with the B1R agonist release IL-4 and VEGF. Stimulation of B1R also caused transient c-JunN-terminal kinase phosphorylation and JunB nuclear translocation, transcription factor that regulates IL-4 expression. The 3D-angiogenesis assay, performed on spheroids of EA.hy923 endothelial cells embedded in a collagen matrix, showed that their cumulative sprout area increased significantly following stimulation with either IL-4 or B1R agonist. Furthermore, these ligands produced significant endothelial cell migration and release of metalloproteases 2 and 9, but did not increase endothelial cell proliferation as measured by 5-bromo-2′-deoxyuridine incorporation. Our results provide experimental evidence that establishes IL-4 and B1R agonist as important angiogenic factors of relevance for skin repair.

Aerogels made of chitosan and chondroitin sulfate at high degree of neutralization: Biological properties toward wound healing: AEROGELS OF CS AND ChS NANOCOMPLEXES

In this study, highly neutralized, highly porous, and ultralight polymeric aerogels prepared from aqueous colloidal suspensions of chitosan (CS) and chondroitin sulfate (ChS) nanocomplexes, formulated as quasi-equimolar amounts of both, are described. These aerogels were designed as healing agents under the inspiration of minimizing the amount of matter applied to wounds, reducing the electrostatic potential of the material and avoiding covalent cross-linkers in order to decrease metabolic stress over wounds. Aerogels synthesized under these criteria are biocompatible and provide specific properties for the induction of wound healing. They do not affect neither the metabolic activity of cultured 3T3 fibroblasts nor the biochemical parameters of experimental animals, open wounds close significantly faster and, unlike control wounds, complete reepithelialization and scarring can be attained 14 days after surgery. Because of its hydration abilities, rapid adaptation to the wound bed and the early accelerator effect of wound closure, the CS/ChS aerogels appear to be functional inducers of the healing. Previous information show that CS/ChS aerogels improve wound bed quality, increase granulation tissue and have pain suppressive effect. CS/ChS aerogels are useful as safe, inexpensive and easy to handle materials for topical applications, such as skin chronic wounds.

Activation of the human keratinocyte B1 bradykinin receptor induces expression and secretion of metalloproteases 2 and 9 by transactivation of epidermal growth factor receptor.

The B1 bradykinin receptor (BDKRB1) is a component of the kinin cascade localized in the human skin. Some of the effects produced by stimulation of BDKRB1 depend on transactivation of epidermal growth factor receptor (EGFR), but the mechanisms involved in this process have not been clarified yet. The primary purpose of this study was to determine the effect of a BDKRB1 agonist on wound healing in a mouse model and the migration and secretion of metalloproteases 2 and 9 from human HaCaT keratinocytes and delineate the signalling pathways that triggered their secretion. Although stimulation of BDKRB1 induces weak chemotactic migration of keratinocytes and wound closure in an in vitro scratch‐wound assay, the BDKRB1 agonist improved wound closure in a mouse model. BDKRB1 stimulation triggers synthesis and secretion of both metalloproteases, effects that depend on the activity of EGFR and subsequent phosphorylation of ERK1/2 and p38 mitogen‐activated protein kinases and PI3K/Akt. In the mouse model, immunoreactivity for both gelatinases was concentrated around wound borders. EGFR transactivation by BDKRB1 agonist involves Src kinases family and ADAM17. In addition to extracellular matrix degradation, metalloproteases 2 and 9 regulate cell migration and differentiation, cell functions that are associated with the role of BDKRB1 in keratinocyte differentiation. Considering that BDKRB1 is up‐regulated by inflammation and/or by cytokines that are abundant in the inflammatory milieu, more stable BDKRB1 agonists may be of therapeutic value to modulate wound healing.

Demonstration of acrosomal membranes using the hypo-osmotic swelling test

Summary. The state of the acrosomal membranes in human spermatozoa was studied by means of the hypo‐osmotic swelling test and indirect immunofluorescence using anti‐boar outer acrosomal membrane antibodies. The swelling phenomenon observed in the acrosomal region was characterized by expansion of the plasma membrane without modification of the outer acrosomal membrane.

Cicatrices hipertróficas y queloides

Los queloides representan una forma patologica de cicatrizacion que desborda los limites de la lesion inicial, en cambio las cicatrices hipertroficas permanecen dentro de los bordes del traumatismo originario. En los queloides y cicatrices hipertroficas observamos una formacion excesiva de tejido reparativo como consecuencia de una alteracion de los sistemas de control en la formacion de colageno. La etiologia de estas entidades no es totalmente conocida, aunque se cree que subyace una predisposicion genetica a la que se anadirian factores desencadenantes. Ambas son dificil de tratar, sobre todo los queloides con un alto grado de recurrencias que en muchas ocasiones requiere asociar diferentes opciones terapeuticas para conseguir su control.