Comparison of Physicochemical, Mechanical, and (Micro-)Biological Properties of Sintered Scaffolds Based on Natural- and Synthetic Hydroxyapatite Supplemented with Selected Dopants.

The specific combinations of materials and dopants presented in this work have not been previously described. The main goal of the presented work was to prepare and compare the different properties of newly developed composite materials manufactured by sintering. The synthetic- (SHAP) or natural- (NHAP) hydroxyapatite serves as a matrix and was doped with: (i) organic: multiwalled carbon nanotubes (MWCNT), fullerenes C60, (ii) inorganic: Cu nanowires. Research undertaken was aimed at seeking novel candidates for bone replacement biomaterials based on hydroxyapatite-the main inorganic component of bone, because bone reconstructive surgery is currently mostly carried out with the use of autografts; titanium or other non-hydroxyapatite -based materials. The physicomechanical properties of the developed biomaterials were tested by Scanning Electron Microscopy (SEM), Dielectric Spectroscopy (BSD), Nuclear Magnetic Resonance (NMR), and Differential Scanning Calorimetry (DSC), as well as microhardness using Vickers method. The results showed that despite obtaining porous sinters. The highest microhardness was achieved for composite materials based on NHAP. Based on NMR spectroscopy, residue organic substances could be observed in NHAP composites, probably due to the organic structures that make up the tooth. Microbiology investigations showed that the selected samples exhibit bacteriostatic properties against Gram-positive reference bacterial strain S. epidermidis (ATCC 12228); however, the property was much less pronounced against Gram-negative reference strain E. coli (ATCC 25922). Both NHAP and SHAP, as well as their doped derivates, displayed in good general compatibility, with the exception of Cu-nanowire doped derivates.

Aspirin and its pleiotropic application.

Aspirin (acetylsalicylic acid), the oldest synthetic drug, was originally used as an anti-inflammatory medication. Being an irreversible inhibitor of COX (prostaglandin-endoperoxide synthase) enzymes that produce precursors for prostaglandins and thromboxanes, it has gradually found several other applications. Sometimes these applications are unrelated to its original purpose for example its use as an anticoagulant. Applications such as these have opened opportunities for new treatments. In this case, it has been tested in patients with cardiovascular disease to reduce the risk of myocardial infarct. Its function as an anticoagulant has also been explored in the prophylaxis and treatment of pre-eclampsia, where due to its anti-inflammatory properties, aspirin intake may be used to reduce the risk of colorectal cancer. It is important to always consider both the risks and benefits of aspirin's application. This is especially important for proposed use in the prevention and treatment of neurologic ailments like Alzheimer's disease, or in the prophylaxis of myocardial infarct. In such cases, the decision if aspirin should be applied, and at what dose may be guided by specific molecular markers. In this revived paper, the pleiotropic application of aspirin is summarized.

Reprogramming and transdifferentiation - two key processes for regenerative medicine.

Regenerative medicine based on transplants obtained from donors or foetal and new-born mesenchymal stem cells, encounter important obstacles such as limited availability of organs, ethical issues and immune rejection. The growing demand for therapeutic methods for patients being treated after serious accidents, severe organ dysfunction and an increasing number of cancer surgeries, exceeds the possibilities of the therapies that are currently available. Reprogramming and transdifferentiation provide powerful bioengineering tools. Both procedures are based on the somatic differentiated cells, which are easily and unlimitedly available, like for example: fibroblasts. During the reprogramming procedure mature cells are converted into pluripotent cells - which are capable to differentiate into almost any kind of desired cells. Transdifferentiation directly converts differentiated cells of one type into another differentiated cells type. Both procedures allow to obtained patient's dedicated cells for therapeutic purpose in regenerative medicine. In combination with biomaterials, it is possible to obtain even whole anatomical structures. Those patient's dedicated structures may serve for them upon serious accidents with massive tissue damage but also upon cancer surgeries as a replacement of damaged organ. Detailed information about reprogramming and transdifferentiation procedures as well as the current state of the art are presented in our review.