Novel opportunities and challenges offered by nanobiomaterials in tissue engineering

Over the last decades, tissue engineering has demonstrated an unquestionable potential to regenerate damaged tissues and organs. Some tissue-engineered solutions recently entered the clinics (eg, artificial bladder, corneal epithelium, engineered skin), but most of the pathologies of interest are still far from being solved. The advent of stem cells opened the door to large-scale production of “raw living matter” for cell replacement and boosted the overall sector in the last decade. Still reliable synthetic scaffolds fairly resembling the nanostructure of extracellular matrices, showing mechanical properties comparable to those of the tissues to be regenerated and capable of being modularly functionalized with biological active motifs, became feasible only in the last years thanks to newly introduced nanotechnology techniques of material design, synthesis, and characterization. Nanostructured synthetic matrices look to be the next generation scaffolds, opening new powerful pathways for tissue regeneration and introducing new challenges at the same time. We here present a detailed overview of the advantages, applications, and limitations of nanostructured matrices with a focus on both electrospun and self-assembling scaffolds.     

Oxygen and carbon isotope variations in Chamelea gallina shells: Environmental influences and vital effects

Stable isotopes in mollusc shells, together with variable growth rates and other geochemical properties, can register different environmental clues, including seawater temperature, salinity and primary productivity. However, the strict biological control over the construction of biominerals exerted by many calcifying organisms can constrain the use of these organisms for paleoenvironmental reconstructions. Biologically controlled calcification is responsible for the so called vital effects that cause a departure from isotopic equilibrium during shell formation, resulting in lower shell oxygen and carbon compared to the equilibrium value. We investigated shell oxygen and carbon isotopic composition of the bivalve Chamelea gallina in six sites along with a latitudinal gradient on the Adriatic Sea (NE Mediterranean Sea). Seawater δ¹⁸O and δ¹³C_DIC varied from North to South, reflecting variations in seawater temperature, salinity, and chlorophyll concentration among sites. Shell δ¹⁸O and δ¹³C differed among sites and exhibited a wide range of values along with the ~400 km latitudinal gradient, away from isotopic equilibrium for both isotopes. These results hampered the utilization of this bivalve as a proxy for environmental reconstructions, in spite of C. gallina showing promise as a warm temperature proxy. Rigorous calibration studies with a precise insight of environment and shell growth are crucial prior to considering this bivalve as a reliable paleoclimatic archive.     

Ectopic expression of Kxhkn5 in the viviparous species Kalanchoe?��?Houghtonii induces a novel pattern of epiphyll development

KxhKN5 (class 1 KNOX gene) was cloned from Kalanchoe × houghtonii with strong tendency to form epiphylls on leaves. KxhKN5 appear to be homologue of BP of A. thaliana on the basis of phylogeny, expression and phenotype analysis. Beside the modification of several plant and leaf traits, the appearance of epiphylls was drastically reduced by both the silencing and the over-expression of KxhKN5 in most of the generated clones. In silenced clones, epiphyll production followed the morphogenetic pathway of the WT plants: somatic embryos outbreak in the centre of each leaf-pedestal, grown in the notch between leaf indentations and were supported by a suspensor. The connection between the epiphyll and the mother plant did not include any vasculature and as a result, the epiphylls dropped easily from the mother plant. The most represented category of over expressor clones, disclosed a novel pattern of epiphyll development: the leaf-pedestals were absent and single bud outbreaks in each leaf notch. Buds developed into shoots which remained attached to the maternal plant by a strong vascular connection. The leaves supporting shoots, produced a thickened midrib and veins, and their lamina ceased expanding. Finally, the leaf/shoot structure resembles a lateral branch. The ectopic expression of KxhKN5 in K. × houghtonii induces a process comparable to the alternation of leaf and shoot formation in other species and support the idea, that it is the variation in shared molecular and developmental processes which produces the growth of specific structures.