No abstract

Cardiovascular diseases are the leading cause of deaths throughout the world. Vascular diseases are mostly treated with autografts and blood vessel transplantations. However, traditional grafting methods have several problems including lack of suitable harvest sites, additional surgical costs for harvesting procedure, pain, infection, lack of donors, and even no substitutes at all. Recently, tissue engineering and regenerative medicine approaches are used to regenerate damaged or diseased tissues. Most of the tissue engineering investigations have been based on the cell seeding into scaffolds by providing a suitable environment for cell attachment, proliferation, and differentiation. Because of the challenges such as difficulties in seeding cells spatially, rejection, and inflammation of biomaterials used, the recent tissue engineering studies focus on scaffold-free techniques. In this paper, the development of novel computer aided algorithms and methods are developed for 3D bioprinting of scaffold-free biomimetic macrovascular structures. Computer model mimicking a real human aorta is generated using imaging techniques and the proposed computational algorithms. An optimized three-dimensional bioprinting path planning are developed with the proposed self-supported model. Mouse embryonic fibroblast (MEF) cell aggregates and support structures (hydrogels) are 3D bioprinted layer-by-layer according to the proposed self-supported method to form an aortic tissue construct.

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Five synthetic substrates containing different amino acid residues at the P3 position (acetyl-X-Arg-Arg-AMC, where X is Gly, Glu, Arg, Val, and Tyr and where AMC represents 7-amindo-4-methylcoumarin) were used to investigate the S3 subsite specificity of cathepsin B. At pH 6.0, the specificity constant, kcat/Km, for tripeptide substrate hydrolysis was observed to increase in the order Glu < Gly < Arg < Val < Tyr. Molecular modeling studies of substrates containing a P3 Glu, Arg, or Tyr covalently bound as the tetrahedral intermediate to the enzyme suggest that the specificity for a P3 Tyr is because of a favorable aromatic-aromatic interaction with Tyr75 on the enzyme as well as a possible H bond between the P3 Tyr hydroxyl and the side chain carboxyl of Asp69.

The potential antimicrobial benefit of high levels of rosmarinic acid (RA) and carvacrol (CA) in oregano (O. onites L.) extract has been limited until now by poor bioavailability arising from the low aqueous-phase solubility and slow dissolution behaviour of the lyophilized extract (E). To address this issue, various ratios of phospholipon 90H (P90H) and 1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol), sodium salt (DMPG) were sonicated, yielding four empty liposomes (L1, L2, L3, and L90). After an initial selection process, Turkish oregano extract was internalized into the more promising candidates. Each empty liposome, extract-loaded liposome (LE1, LE2, and LE3), and freeze-dried control (E) was assessed in terms of structure, composition, RA and CA dissolution profile, storage stability, and, when relevant, zeta potential. Empty liposome L1, which was prepared using P90H and DMPG in a 1:1 ratio, displayed the most convenient encapsulation traits among the four unloaded types. Loaded liposome LE1, obtained by combining oregano extract and L1 in a 1:1 ratio, proved superior as a vehicle to deliver RA & CA when compared against control freeze-dried E and test liposomes LE2 and LE3. Dissolution profiles of the active compounds RA and CA in loaded liposomes were determined using a semi-automated dissolution tester. The basket method was applied using artificial gastric juice without pepsin (AGJ, 50rpm, 500mL). The pH value was maintained at 1.5 (37 ± 0.5°C). Aliquots (5ml) were manually extracted from parallel dissolution vessels at 1, 3, 5, 7, 10, 15, 20, 25, 30, 45, and 60-minute time points. Dissolution tests, run to completion on LE1, showed that approximately 99% of loaded CA and 88% of RA had been released. Shorter dissolution times were also noted in using LE1. In particular, the release profile of CA and RA had levelled off after only 25 minutes, respectively, depicting an impressive 3.0–3.3 and 2.3-2.6 rate increase compared to the freeze-dried control extract. The improved dispersibility of RA and CA in the form of LE1 was supported by particle size and zeta potential measurements of the liposome, yielding 234.3nm and −30.9mV, respectively. The polydispersity index value was 0.35, indicating a reasonable particle size distribution. To study storage stability, liposomes were stored (4°C, 6 months) in amber coloured glass containers (4 oz.). Each container held 30 capsules, which were stored according to the ICH guidelines prescribed for long-term storage (25°C ± 2°C; 60% ± 5% RH). Triplicate samples were withdrawn after 0, 3, 6, 9, and 12 months for analysis. Lastly, LE1 displayed good storage stability. The results imply that RA and CA can be conveniently and routinely delivered via oral and mucosal routes by first internalizing oregano extracts into appropriately engineered liposomes.