if you want to see viable cells on the scaffolds you can use TEM images.

Hi Darioush,

it depends from the scaffold you're using, for hydrogel you could use fluorescence live-dead assay (Calcein AM-Propidium from Sigma or other brand), otherwise sectioning and histological analyis would help to ubderstand cells viability.

good luck

1) You can use live dead staining kits. Most of the companies have those.

http://www.thermofisher.com/us/en/home/brands/molecular-probes/key-molecular-probes-products/live-dead-viability-brand-page.html

2) If the scaffold is small enough to keep inside multiwell plates, and is porous enough. You can use MTT sort of assays. Might be tricky and you need to design your experiment well with controls.

http://www.thermofisher.com/us/en/home/references/protocols/cell-culture/mtt-assay-protocol/vybrant-mtt-cell-proliferation-assay-kit.html

I am attaching a link where I did Propidium iodide staining to stain dead cells. Remaining DAPI stained cells were considered live.

https://www.jove.com/video/52242/high-throughput-characterization-adult-stem-cells-engineered-for

You can try:

Alamar Blue assay or MTT assay

Live dead assay