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).
Stem cells have the unique ability to self-renew or differentiate themselves into various cell types in response to appropriate signals. These cells are especially important for tissue repair, regeneration, replacement, or in the case of hematopoietic stem cells (HSCs) to differentiate into various myeloid populations. Appropriate signals refer to the growth factor supplements or cytokines that mediate differentiation of various stem cells into the required differentiated form. For instance, HSCs can be differentiated into dendritic cells (with IL-4 and GM-CSF), macrophages (with m-CSF) and MDSCs (with IL-6 and GM-CSF). Human pluripotent stem cells (hPSCs) and induced pluripotent stem cells (iPSCs) can be first cultured in neural differentiation media (GSK3𝛃-i, TGF𝛃-i, AMPK-i, hLIF) to form neural rosettes, which can be differentiated into neural or glial progenitors (finally differentiated into oligodendrocytes). Neural progenitors can be finally differentiated into glutaminergic (dibytyryl cAMP, ascorbic acid) and dopaminergic (SHH, FGF-8, BDNF, GDNF, TGF-𝛃3) neurons. Thus, it is important to first identify the self-renewing cell line: its source and its final differentiation state, followed by the supplements and cytokines required for the differentiation, and final use. Timelines are another thing that is considered. For instance, it takes 7-10 days to form neural rosettes from iPSCs and 3 days to differentiate neural progenitors to neurons. Finally, the stability for stem cell culture media varies. It is advised to make fresh media every time when differentiating HSCs to myeloid populations, whereas neural differentiation media may remain stable for two weeks when stored in dark between 2-8C.
The kit works good in human tissue biopsy samples even with minimum amount of tissue.
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.
Get tips on using GeneChip® Human Genome U133 Plus 2.0 Array to perform Microarray Gene expression arrays - Rhesus monkey brain tissue Biotin
Get tips on using Anti-Human FMC7 FITC/CD23 PE/CD19 PerCP-Cy™5.5 to perform Flow cytometry Anti-bodies Human - CD23
Get tips on using CD171 (L1CAM) Antibody, anti-human, PE-Vio® 770, REAfinity™ to perform Flow cytometry Anti-bodies Human - CD171/L1CAM
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