Inflammatory and regenerative processes in bioresorbable synthetic pulmonary valves up to two years in sheep-Spatiotemporal insights augmented by Raman microspectroscopy.

In situ heart valve tissue engineering is an emerging approach in which resorbable, off-the-shelf available scaffolds are used to induce endogenous heart valve restoration. Such scaffolds are designed to recruit endogenous cells in vivo, which subsequently resorb polymer and produce and remodel new valvular tissue in situ. Recently, preclinical studies using electrospun supramolecular elastomeric valvular grafts have shown that this approach enables in situ regeneration of pulmonary valves with long-term functionality in vivo. However, the evolution and mechanisms of inflammation, polymer absorption and tissue regeneration are largely unknown, and adverse valve remodeling and intra- and inter-valvular variability have been reported. Therefore, the goal of the present study was to gain a mechanistic understanding of the in vivo regenerative processes by combining routine histology and immunohistochemistry, using a comprehensive sheep-specific antibody panel, with Raman microspectroscopy for the spatiotemporal analysis of in situ tissue-engineered pulmonary valves with follow-up to 24 months from a previous preclinical study in sheep. The analyses revealed a strong spatial heterogeneity in the influx of inflammatory cells, graft resorption, and foreign body giant cells. Collagen maturation occurred predominantly between 6 and 12 months after implantation, which was accompanied by a progressive switch to a more quiescent phenotype of infiltrating cells with properties of valvular interstitial cells. Variability among specimens in the extent of tissue remodeling was observed for follow-up times after 6 months. Taken together, these findings advance the understanding of key events and mechanisms in material-driven in situ heart valve tissue engineering. STATEMENT OF SIGNIFICANCE: This study describes for the first time the long-term in vivo inflammatory and regenerative processes that underly in situ heart valve tissue engineering using resorbable synthetic scaffolds. Using a unique combinatorial analysis of immunohistochemistry and Raman microspectroscopy, important spatiotemporal variability in graft resorption and tissue formation was pinpointed in in situ tissue-engineered heart valves, with a follow-up time of up to 24 months in sheep. This variability was correlated to heterogenous regional cellular repopulation, most likely instigated by region-specific differences in surrounding tissue and hemodynamics. The findings of this research contribute to the mechanistic understanding of in situ tissue engineering using resorbable synthetics, which is necessary to enable rational design of improved grafts, and ensure safe and robust clinical translation.

Raman spectroscopy as an analytical tool for melanoma research.

BACKGROUND: Raman spectroscopy is an optical noninvasive screening technology that generates individual fingerprints of living cells by reflecting their molecular constitution. AIM: To discriminate melanoma cells from melanocytes, to identify drug-induced melanoma cell death stages (apoptosis, necrosis, autophagy) and to assess the susceptibility of melanoma cells to anticancer therapy. METHODS: We used Raman spectroscopy on normal and melanoma cells, and on wild-type (WT) and mutant melanoma cells, to investigate whether the technique could distinguish between different types of cells, identify mutations and evaluate response to anticancer therapy. RESULTS: Using the multivariate principal component analysis of the Raman spectra, melanocytes could be distinguished from melanoma cells, and WT melanoma cells could be distinguished from melanoma cells with BRAF or NRAS mutations. When we used the apoptosis inducer staurosporine, the necrosis inducer 3-bromopyruvate and the autophagy inducer resveratrol to induce cell death in SKMEL28 melanoma cells, Raman spectroscopy clearly distinguished between these three types of cell death, as confirmed by immunoblotting. Finally, the technique could discriminate between different melanoma cell lines according to their susceptibility to high-dose ascorbate. CONCLUSIONS: Raman spectroscopy is a powerful noninvasive tool to distinguish between melanocytes and melanoma cells, to analyze the specific type of cell death in melanoma cells, and to predict the susceptibility of melanoma cells to anticancer drugs.

[A pair of spectacles to improve the information from the x-ray photograph and from the radioscopy on the television screen (author's transl)]. / Eine Betrachtungsbrille zur Verbesserung der Information aus dem Röntgenbild und bei Durchleuchtung am Fernseschirm

Here a pair of spectacles is introduced which, in screening the lateral incidence of light and in variably cross fading the risual point eliminates the contrast-diminishing intraocular proceeding stray light. It helps to achieve an improvement of the contrast by considering the x-ray photograph or television image. The result is that details are easier perceptible.