I have this problem for sometime that Microglia cells in these PLL coated wells are dying after sometime cause they don't adhere to the coverglasses, I've tried different strategies and it shouldn't be a complicated process but still nothing :(
I usually put my poly-L-Lysine in my wells for 15 min, then I rince twice in DPBS. After that you can either plate your cells or keep your coated plate at 4°C for one or 2 weeks before plating.