Quantification of the DNA damage induced by chemotherapy in patient cells may aid in personalization of the dose used. However, assays to evaluate individual patient response to chemotherapy are not available today. Here, we present an assay that quantifies single-stranded lesions caused by the chemotherapeutic drug Bleomycin (BLM) in peripheral blood mononuclear cells (PBMCs) isolated from healthy individuals. We use base excision repair (BER) enzymes to process the DNA damage induced by BLM and then extend the processed sites with fluorescent nucleotides using a DNA polymerase. The fluorescent patches are quantified on single DNA molecules using fluorescence microscopy. Using the assay, we observe a significant variation in the in vitro induced BLM damage and its repair for different individuals. Treatment of the cells with the BER inhibitor CRT0044876 leads to a lower level of repair of BLM-induced damage, indicating the ability of the assay to detect a compromised DNA repair in patients. Overall, the data suggest that our assay could be used to sensitively detect the variation in BLM-induced DNA damage and repair in patients and can potentially be able to aid in personalizing patient doses.

对患者细胞中化疗引起的 DNA 损伤进行量化可能有助于个性化所用剂量。然而，目前还没有评估个体患者对化疗反应的分析方法。在这里，我们提出了一种测定法，该测定法对从健康个体分离的外周血单核细胞 (PBMC) 中由化学治疗药物博来霉素 (BLM) 引起的单链病变进行量化。我们使用碱基切除修复 (BER) 酶来处理 BLM 诱导的 DNA 损伤，然后使用 DNA 聚合酶用荧光核苷酸扩展处理过的位点。使用荧光显微镜在单个 DNA 分子上量化荧光斑块。使用该测定，我们观察到体外的显着变化诱导 BLM 损伤及其对不同个体的修复。用 BER 抑制剂 CRT0044876 处理细胞导致 BLM 诱导损伤的修复水平较低，表明该测定能够检测患者中受损的 DNA 修复。总体而言，数据表明我们的测定可用于灵敏地检测 BLM 诱导的患者 DNA 损伤和修复的变化，并可能有助于个性化患者剂量。