Animal Models and Methods of Myocardial Infarction Induction and the Role of Tissue Engineering in the Regeneration of Damaged Myocardium.

The introduction of an experimental animal model for myocardial infarction (MI) has particular importance. Research done on large animals provides valuable information for the researchers because of the similar characteristics of their hearts compared to humans, but the cost of purchasing and maintaining them is high. In comparison, using small animals has advantages, such as they are easy to work with and have low purchase and maintenance costs. However, in some of these animals, due to less similarity of the heart to humans, they cannot simulate the natural pathogenesis of human MI. Moreover, there are different methods for the induction of MI in animals; each has its own advantages and disadvantages. However, a method must be chosen to simulate the natural pathogenesis of MI with minimal complication. Currently, attempts are being made for myocardial regeneration after MI using the direct transplantation of stem cells or an engineered scaffold. The scaffold creates a 3D ambiance for the cultured cells. The task of tissue engineering is to optimize the scaffold with appropriate systems for the separation, proliferation, and differentiation of the desired cells until they are capable of promoting the threedimensional and appropriate growth of the tissue. The purpose of tissue engineering in cardiac is the use of scaffolds and cells in the damaged area, followed by the improvement of the heart function through automatic pulsation, communication with the host vessels, and electrical coupling with the myocardium, eventually creating a force to increase the heart function.

Effects of 1, 25-dihydroxy vitamin D3 on clinical symptoms, pro-inflammatory and inflammatory cytokines in calves with experimental pneumonia.

1, 25-dihydroxycholecalciferol is recognized as a potent immune-modulator which can fight against the pathogens via the activation of vitamin D3 receptors (VDRs), as well as stimulating various cytokines in infectious diseases. In the present study, because of the vitamin D3 has an appropriate immunomodulatory, the effects of this vitamin on the levels of pre-inflammatory and anti-inflammatory cytokines have been investigated in calves with experimental pasteurellosis. This study was experimentally carried out on 10 Holstein crossbred male calves (2-4 months) that were divided into two groups. Prepared Pasteurella multocida (3 × 109 CFU/mL) was inoculated in the trachea with a lavage catheter and then the treatment group was injected with 1, 25-dihydroxycholecalciferol after confirming pneumonia. Blood sampling, clinical symptoms scoring and radiological evaluation were recorded for both groups at different time intervals. The prescription of, vitamin D3 to the treatment group caused a decline in clinical symptoms score and changed interstitial and alveolo-interstitial lung pattern to such a degree that it could recover in comparison with the control group. The concentrations of pro-inflammatory cytokines (i.e., IL-1ß, IL-6, and TNF-α) and the chemokine (IL-8) showed a significant decrease in the treatment group while the concentration of IL-10 increased in the treatment groups following the vitamin D3 injection (P = .001). The evidence from the current study suggests that vitamin D3 exert the immunomodulatory effects in infectious diseases through the regulation of cytokines and activation of VDR pathways to produce antimicrobial peptides.

Generation of Lung and Airway Epithelial Cells from Embryonic Stem Cells In Vitro.

The epithelium covers the internal surface of the lung airways and is composed of numerous cell types that arise from the anterior foregut endoderm. The ability to generate pulmonary cells from embryonic stem cells will allow study of lung development, drug screening, regenerative medicine, and modeling of lung diseases. The aim of this review is to describe the methods used to produce lung cells in vitro, based on mechanisms of lung development in during embryology.