Marine biomaterials: Biomimetic and pharmacological potential of cultivated Aplysina aerophoba marine demosponge

Marine demosponges of the Verongiida order are considered a gold-mine for bioinspired materials science and marine pharmacology. The aim of this work was to simultaneously isolate selected bromotyrosines and unique chitinous structures from A. aerophoba and to propose these molecules and biomaterials for possible application as antibacterial and antitumor compounds and as ready-to-use scaffolds for cultivation of cardiomyocytes, respectively. Among the extracted bromotyrosines, the attention has been focused on aeroplysinin-1 that showed interesting unexpected growth inhibition properties for some Gram-negative clinical multi-resistant bacterial strains, such as A. baumannii and K. pneumoniae, and on aeroplysinin-1 and on isofistularin-3 for their anti-tumorigenic activity. For both compounds, the effects are cell line dependent, with significant growth inhibition activity on the neuroblastoma cell line SH-SY5Y by aeroplysinin-1 and on breast cancer cell line MCF-7 by isofistularin-3. In this study, we also compared the cultivation of human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) on the A. aerophoba chitinous scaffolds, in comparison to chitin structures that were pre-coated with Geltrex™, an extracellular matrix mimetic which is used to enhance iPSC-CM adhesion. The iPSC-CMs on uncoated and pure chitin structures started contracting 24 h after seeding, with comparable behaviour observed on Geltrex-coated cell culture plates, confirming the biocompatibility of the sponge biomaterial with this cell type. The advantage of A. aerophoba is that this source organism does not need to be collected in large quantities to supply the necessary amount for further pre-clinical studies before chemical synthesis of the active compounds will be available. A preliminary analysis of marine sponge bioeconomy as a perspective direction for application of biomaterials and secondary bioactive metabolites has been finally performed for the first time.

3D chitinous scaffolds derived from cultivated marine demosponge Aplysina aerophoba for tissue engineering approaches based on human mesenchymal stromal cells

The recently discovered chitin-based scaffolds derived from poriferans have the necessary prosperities for potential use in tissue engineering. Among the various demosponges of the Verongida order, Aplysina aerophoba is an attractive target for more in-depth investigations, as it is a renewable source of unique 3D microporous chitinous scaffolds. We found these chitinous scaffolds were cytocompatible and supported attachment, growth and proliferation of human mesenchymal stromal cells (hMSCs) in vitro. Cultivation of hMSCs on the scaffolds for 7days resulted in a two-fold increase in their metabolic activity, indicating increased cell numbers. Cells cultured onto chitin scaffolds in differentiation media were able to differentiate into the chondrogenic, adipogenic and osteogenic lineages, respectively. These results indicate A. aerophoba is a novel source of chitin scaffolds to futher hMSCs-based tissue engineering strategies.

[Gastrointestinal gastric tumor (GIST) as a cause of massive hemorrhage from the upper digestive tract]

Gastrointestinal stromal tumors GIST are rare mesenchymal tumors of the gastrointestinal tract characterized by expression of a receptor that activates tyrosine kinase called C- kit. Since malignant GIST has an extremely poor prognosis even after surgical resection. The developement of a tyrosine kinase inhibitor, STI571/imatinib mesylate/Gleevec, Glivec which inhibits the BCR-ABL, PDGF-R alpha, and C-Kit receptors, has changed the management of unresectable malignant GIST and has improved the survival of patients with metastaic disease. We report a 32 year old male patient with subcardiale gastric GIST and massive gastrointestinale bleeding. The patient underwent total gastrectomy, D2 lymphadenestomy, distal pancreatectomy and splenectomy on 02.02. 2004. Histopathology examination of the primary tumor revealed a strong C-Kit expression and CD 34 +++, Ki67 20 and so called "Pure GIST" was approved Liver metastasis was detected on ultrasound and CT 12 months later and segmentectomy S7 was performed on 23.03.2005. Postoperative course was uneventfull. HP examination--malignant 35 x 30 mm sarcoma like tumor of mesenchymal origin. The patient received adjuvant imatinib-mesylate Gleevec Novartis Pharma Basel 400 mg a day. The initial complete response to treatment continued to 24 monts postoperatively Imatinib is a recent and very promising tretemenextirpation remains the only curative treatment of malignant GIST as evideneced by our patient.

Pituitary enlargement due to primary hypothyroidism: growth hormone response to GHRH, GHRP-6 and GHRH plus GHRP-6

GH secretion after growth hormone-releasing hormone (GHRH), growth hormone releasing peptide-6 (GHRP-6) and after combined administration of both peptides was studied in a patient with lactotrope and thyrotrope hyperplasia due to primary hypothyroidism. Pituitary pseudotumor disappeared after thyroid hormone replacement; this was evidenced by magnetic resonance imaging (NMR). There was no difference between areas under the curve (AUCzero-120 min) during GHRH test before and after thyroid hormone replacement (136.5 vs 129.0 micrograms/l min). Maximal GH increases over basal values (delta GH) did not change (1.5 and 1.9 micrograms/l). GH secretion induced by GHRP-6 increased after treatment (AUCzero-120 min 197.2 vs 650.4 micrograms/l min). delta GH increments were 4.0 and 18.3 micrograms/l before and after therapy respectively. When the peptides were administered together a synergistic effect on GH secretion was observed but GH release was much more powerful after pituitary pseudotumor disappearance (AUCzero-120 min 1043.2 vs 2046.7 micrograms/l min). This was accompanied by increased delta GH (22.7 vs 35.5 micrograms/l). The synergic action of peptides normalized in euthyroid condition and after the resolution of pituitary pseudotumor mainly due to improved GH response to GHRP-6. Blunted response of GH to GHRP-6 and GHRP-6 plus GHRH were in part due to known effects of hypothyroidism on GH secretion. Hypothalamopituitary disconnection and/or decrease in the synthesis of an unknown factor in the hypothalamus which mediates the effects of GHRP-6 may have participated in the GH responsiveness of this patient. This case adds to in vivo evidence that GHRP-6 operates through a non-GHRH dependent mechanism.