Immunohistochemistry CD31

Flow cytometry is an immunophenotyping technique whereby sing cell suspensions are stained for either cell surface markers or intracellular proteins by fluorescently-labelled antibodies and analyzed with a flow cytometer, where fluorescently-labelled molecules are excited by the laser to emit light at varying wavelengths, which is then detected by the instrument. There are several key criteria which are required to be kept in mind while designing a flow experiment- 1. Antibody titration (optimal dilution of antibodies should be calculated in order to avoid over- or under- saturated signals for proper detection of surface and intracellular markers), 2. Precision (3 or more replicates of the sample should be used per experiment), 3. Specificity (proper isotype controls should be included in the experiment), 4. Day-to-day variability (experiments should be repeated 3 or more times to ensure consistency and avoid variability due to flow cytometer settings), 5. Antibody interaction (Fluorescence minus one or FMO should be used, which is the comparison of signals from panel minus one antibody vs. the full panel), and 6. Antibody stability (fluorescently-labelled antibodies should be stored at 4C).

When extracting nucleic acids from cell cultures, thorough homogenization of cells via vortexing in lysis buffer is very necessary. Choose the best RNA isolation method keeping in mind the downstream applications, generally, column-based isolations result in clean and concentrated RNA samples. Downstream applications like sequencing and cDNA synthesis require high-quality RNA, always treat the samples with DNases and check their integrity by running a gel.

Short hairpin or small hairpin RNA (shRNA) is artificial RNA, which has a hairpin loop structure, and uses inherent microRNA (miRNA) machinery to silence target gene expression. This is called RNA interference (RNAi). These can be delivered via plasmids or viral/bacterial vectors. Challenges in shRNA-mediated gene silencing include 1. Off-target silencing, 2. Packaging shRNA encoding lentivirus, and 3. Stable transduction in cells. RNAi has been designed to have anywhere from 19-27 bs, but the most effective design has 19 bp. In case commercial shRNAs are not available, potential target sites can be chosen within exon, 5’- or 3’ UTR, depending on which splice variants of the gene are desired. One should use the latest algorithms and choose at least two different sequences, targeting different regions, in order to have confidence in overcoming off-target effects. A BLAST search after selecting potential design will eliminate potential off-target sequences. For the second challenge, sequencing the vector using primers for either strand (50-100 bp upstream) is suggested, along with using enzymatic digestion on agarose gel for the vector. Next, once the shRNA-containing vector is packaged in a virus, it is important to check the viral titer before transduction. Finally, using a marker in the lentiviral vector (fluorescent protein or antibiotic resistance), along with qPCR for target gene expression can help in determining the efficacy of transduction and shRNA on its target site.

Gene silencing through the use of small interfering RNA (siRNA) has become a primary tool for identifying disease-causing genes. There are several aspects for preparing and delivering effective siRNA to knockdown a target gene. The length of siRNA should be 21–23nt long with G/C content 30–50%. If a validated siRNA sequence for your target gene is not available, use siRNA generated against the entire target gene ORF. Always work with two or three different siRNA constructs to get reliable results. If you are not sure how much siRNA to use for a given experiment, start with a transfection concentration of 10-50 nM and use siRNA-specific transfection reagent to ensure efficient siRNA delivery in a wide range of cells.

Get tips on using RNeasy Mini Kit to perform RNA isolation / purification Cells - primary human CD14+ monocytes

Protein isolation is a technique that involves isolation and/ or purification of protein from cells or tissues via chromatography or electrophoresis. The major challenges in protein isolation include: 1. The concentration of proteins in cells is variable and tends to be small for some intracellular proteins. Unlike nucleic acids, proteins cannot be amplified. 2. Proteins are more unstable than nucleic acids. They are easily denatured under suboptimal temperature, pH or salt concentrations. 3. Finally, no generalized technique/protocol can be applied for protein isolation. Proteins may have different electrostatic (number of positively or negatively charged amino acids) or hydrophobic properties. Therefore, protein purification requires multiple steps depending on their charge (a negatively charged resin/column for positively charged proteins and vice-versa), dissolution (using detergents) and unlike in the case of DNA and RNA, instead of using salts, proteins should be isolated by isoelectric precipitation.

Get tips on using RNeasy Plus Mini Kit to perform RNA isolation / purification Cells - primary human CD14+ monocytes

Get tips on using Human IL-6R alpha Antibody to perform Flow cytometry Anti-bodies Human - CD126/IL-6Ralpha

Get tips on using AllPrep DNA/RNA Mini Kit to perform RNA isolation / purification Cells - primary human CD14+ monocytes

Get tips on using CelLytic™ MT Cell Lysis Reagent to perform Protein isolation Mammalian cells - Human CD14+ cells