Myocardial infarction stabilization by cell-based expression of controlled Vascular Endothelial Growth Factor levels

Vascular Endothelial Growth Factor (VEGF) can induce normal or aberrant angiogenesis depending on the amount secreted in the microenvironment around each cell. Towards a possible clinical translation, we developed a Fluorescence Activated Cell Sorting (FACS)‐based technique to rapidly purify transduced progenitors that homogeneously express a desired specific VEGF level from heterogeneous primary populations. Here, we sought to induce safe and functional angiogenesis in ischaemic myocardium by cell‐based expression of controlled VEGF levels. Human adipose stromal cells (ASC) were transduced with retroviral vectors and FACS purified to generate two populations producing similar total VEGF doses, but with different distributions: one with cells homogeneously producing a specific VEGF level (SPEC), and one with cells heterogeneously producing widespread VEGF levels (ALL), but with an average similar to that of the SPEC population. A total of 70 nude rats underwent myocardial infarction by coronary artery ligation and 2 weeks later VEGF‐expressing or control cells, or saline were injected at the infarction border. Four weeks later, ventricular ejection fraction was significantly worsened with all treatments except for SPEC cells. Further, only SPEC cells significantly increased the density of homogeneously normal and mature microvascular networks. This was accompanied by a positive remodelling effect, with significantly reduced fibrosis in the infarcted area. We conclude that controlled homogeneous VEGF delivery by FACS‐ purified transduced ASC is a promising strategy to achieve safe and functional angiogenesis in myocardial ischaemia

Preparation and characterization of Sr-Ti-hardystonite (Sr-Ti-HT) nanocomposite for bone repair application

Objective(s): Hardystonite (HT) is Zn-modified silicate bioceramics with promising results for bone tissue regeneration. However, HT possesses no obvious apatite formation. Thus, in this study we incorporated Sr and Ti into HT to prepare Sr-Ti-hardystonite (Sr-Ti-HT) nanocomposite and evaluated its in vitro bioactivity with the purpose of developing a more bioactive bone substitute material. Materials and methods:The HT and Sr-Ti-HT were prepared by mechanical milling and subsequent heat treatment. Calcium oxide (CaO), zinc oxide (ZnO) and silicon dioxide (SiO2) (all from Merck) were mixed with molar ratio of 2:1:2. The mixture of powders mixture was then milled in a planetary ball mill for 20 h. In the milling run, the ball-to-powder weight ratio was 10:1 and the rotational speed was 200 rpm. After synthesis of HT, 3% nanotitanium dioxide (TiO2, Degussa) and 3% strontium carbonate (SrCO3, Merck) were added to HT and then the mixture was ball milled and calcined at 1150°C for 6 h. Simultaneous thermal analysis (STA), X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Fourier transform infra-red spectroscopy (FT-IR) performed to characterize the powders. Results:XRD and FT-IR confirmed the crystal phase and silicate structure of HT and TEM images demonstrated the nanostructure of powders. Further, Sr-Ti-HT induced apatite formation and showed a higher human mesenchymal stem cell (hMSCs) adhesion and proliferation compared to HT. Conclusion:Our study revealed that Sr-Ti-HT with a nanostructured crystal structure of 50 nm, can be prepared by mechanical activation to use as biomaterials for orthopedic applications

Stem cells and injectable hydrogels: Synergistic therapeutics in myocardial repair.

One of the major problems in the treatment of cardiovascular diseases is the inability of myocardium to self-regenerate. Current therapies are unable to restore the heart's function after myocardial infarction. Myocardial tissue engineering is potentially a key approach to regenerate damaged heart muscle. Myocardial patches are applied surgically, whereas injectable hydrogels provide effective minimally invasive approaches to recover functional myocardium. These hydrogels are easily administered and can be either cell free or loaded with bioactive agents and/or cardiac stem cells, which may apply paracrine effects. The aim of this review is to investigate the advantages and disadvantages of injectable stem cell-laden hydrogels and highlight their potential applications for myocardium repair

Stem cells and injectable hydrogels: Synergistic therapeutics in myocardial repair.

One of the major problems in the treatment of cardiovascular diseases is the inability of myocardium to self-regenerate. Current therapies are unable to restore the heart's function after myocardial infarction. Myocardial tissue engineering is potentially a key approach to regenerate damaged heart muscle. Myocardial patches are applied surgically, whereas injectable hydrogels provide effective minimally invasive approaches to recover functional myocardium. These hydrogels are easily administered and can be either cell free or loaded with bioactive agents and/or cardiac stem cells, which may apply paracrine effects. The aim of this review is to investigate the advantages and disadvantages of injectable stem cell-laden hydrogels and highlight their potential applications for myocardium repair

Advances in silicon nitride ceramic biomaterials for dental applications – A review

Titanium and its alloys have been utilized as the preferred material for dental implants due to its mechanical and biological performance leading to high clinical success rates. Nonetheless, ceramic-based dental implants have been developed as the demands for non-metallic dental restorations have increased. The advent of bioceramics has increased the possibility of resolution in regenerative processes challenges for dentistry applications. In this regard, silicon nitride (Si3N4) as a non-oxide ceramic has the potential for oral applications which is ground in its bactericidal properties. The present work aimed to shed light on Si3N4 ceramic being used for future dental applications. As a concluding remark, the bactericidal and immunomodulatory properties of Si3N4 together with its radiolucency are inferred as a suitable contender in oral cavity and dental applications