Hi Argha,

If not a single cell adheres to your cell culture dish (assuming plastic one; HUVEC do not like glass surface that much), that may suggest: 1) the cells are not alive (rare but possible scenario, depending on how they were frozen/stored/transported and thawed), 2) the gelatin coating is not working (check your gelatin solution concentration/pH, coating duration etc). If available, please use fibronectin (1-3ug/ml in PBS) for coating; works really well.

Overall, the cells adhere better without DMSO. However, not to loose a lot of cells during the initial centrifugation after the cell thawing (when they are really fragile), some investigators allow cells to adhere to the dishes for 2-4 hrs and then change cell culture medium to remove DMSO.

Not sure what cell culture medium are you using for HUVEC? Be extra careful by thawing the cells from the frozen stock!

Hope that will give you something to consider.

Best of luck!

@Gediminas thank you sir for your kind help. We were able to solve our problem with your suggestion. Thanks a ton