A biomimetic porous hydrogel of gelatin and glycosaminoglycans cross-linked with transglutaminase and its application in the culture of hepatocytes.

The development of blended gelatin and glycosaminoglycan (GAG) scaffolds can potentially be used in many soft tissue engineering applications since these scaffolds mimic the structure and biological function of native extracellular matrix (ECM). In this study, we were able to obtain a gelatin-GAG scaffold by using a concentrated emulsion templating technique known as high internal phase emulsion (HIPE), in which a prevailing in volume organic phase is dispersed in the form of discrete droplets inside an aqueous solution of three biopolymers represented by gelatin, hyaluronic acid (HA) and chondroitin sulfate (CS) in the presence of a suitable surfactant. In order to preserve the bioactive potential of the biopolymers employed, the cross-linking procedure involved the use of transglutaminase (MTGase) that catalyzes the formation of covalent N-ε-(γ-glutamyl) lysine amide bonds. Since neither HA nor CS possess the necessary primary amino groups toward which MTGase is active, they were functionalized with the dipeptide glycine-lysine (GK). In this way the introduction of foreign cross-linking bridging units with an unpredictable biocompatibility was avoided. These enzymatic cross-linked gelatin-GAG scaffolds were tested in the culture of primary rat and C3A hepatocytes. Results underlined the good performance of this novel support in maintaining and promoting hepatocyte functions in vitro.

Glutathione peroxidase (GPX) activity in seminal plasma of healthy and infertile males.

Human spermatozoa are more dependent on glutathione peroxidase/glutathione reductase (GPX/GR) system, via reduced glutathione (GSH), to inactivate reactive oxygen metabolites (ROMs) such as hydrogen peroxide and organic hydroperoxides. To demonstrate whether there is a substantial difference in GPX activity between normal and pathological seminal plasma, we decided to evaluate the activity of this enzyme in healthy subjects and infertile males with normal hormonal patterns. Our results demonstrate that in healthy subjects the seminal plasma contains a GPX activity that is about 10 times greater than the GPX activity detected in the seminal plasma of infertile males. By using specific antibodies against plasmatic GPX (GPX3), we also demonstrate that enzymatic activity, detected in the seminal plasma of both healthy and infertile males is GPX3. Therefore, the evaluation of GPX activity in human seminal plasma could be a new useful marker of gonadal function in men.