Introduction: Spinal metastatic disease is a major cause of morbidity in patients with cancer. Spinal bone marrow represents a unique reservoir for several types of immune cells, many of which have well-described roles in cancer initiation and progression. However, the precise cellular mechanisms that regulate metastatic disease in the spine remain elusive and require further study. Here, we describe a sampling technique that permits harvesting of spinal metastases and associated tissues, with special attention to nuances required for downstream analysis by flow cytometric assay
Methods: A step-by-step technical guide for the harvesting and preparation of metastatic tumor specimen during spine surgery is provided, with a focus on our personal experience with sample handling and optimization. Specimens obtained intraoperatively included aspirates of tumor-laden foci as well as grossly uninvolved adjacent bone marrow. Two illustrative cases of lung cancer metastatic to the spine are included. Flow cytometric analyses of immune cell infiltrates are provided, highlighting the potential applications of this technique.
Results: Samples from both patients were successfully harvested, preserved, and subjected to analysis. Examples of flow cytometric data obtained by this method revealed an unexpected diversity of immune cells with phenotypes known to antagonize efficacious antitumor immune responses.
Conclusions: Here we present a safe and effective method of obtaining and preserving metastatic spine tissue, specifically for subsequent cellular analysis. Spine surgeons should be familiar with these techniques, which enable further investigation into factors regulating the initiation and progression of metastatic tumors in the spine.
Patient Care: This work will enhance our understanding of the immune microenvironment associated with spine metastases and help build the foundation for future study of immune-based interventions in this setting.
Learning Objectives: By the end of the session, participants will be able to discuss how Spine Surgeons can contribute to basic science laboratory efforts studying metastatic disease in the spine.