Researchers present an optimized protocol for single nuclei RNA sequencing (snRNA-seq) that is fast, low, cost, and time effective due to the elimination of cell sorting and ultra-centrifugation. Both human and mouse tissue biopsies were assessed. Human kidney graft biopsies were collected from five kidney transplant recipients. Mouse needle biopsies were collected from heart, liver, kidney, spleen, lung, duodenum, large intestine, bone marrow and brain.