I typically extract DNA from whole blood using a Qiagen kit link here: https://www.qiagen.com/ja-us/products/discovery-and-translational-research/dna-rna-purification/dna-purification/genomic-dna/qiaamp-dna-blood-kits/ (RBC lysis, cell lysis, then within 2 years, protein precipitation, DNA precipitation after adding isopropanol, wash with ethanol, rehydrate DNA). I want to extract DNA from PBMCs which have been frozen in aliquots of 5 million cells in media comprised of 90% FBS, 10% DMSO. I've tried this before by thawing the PBMCs and proceeding onto the cell lysis step in my normal DNA extraction protocol but have had no success. Can anyone offer tips on how to extract DNA from frozen PBMCs? Thank you in advance!