A permanent window for the murine lung enables high-resolution imaging of cancer metastasis

Abstract

Stable, high-resolution intravital imaging of the lung has become possible through the utilization of vacuum-stabilized imaging windows. However, this technique is extremely invasive and limited to only hours in duration. Here we describe a minimally invasive, permanently implantable window for high-resolution intravital imaging of the murine lung that allows the mouse to survive surgery, recover from anesthesia, and breathe independently. Compared to vacuum-stabilized windows, this window produces the same high-quality images without vacuum-induced artifacts; it is also less invasive, which allows imaging of the same lung tissue over a period of weeks. We further adapt the technique of microcartography for reliable relocalization of the same cells longitudinally. using commonly employed experimental, as well as more clinically relevant, spontaneous metastasis models, we visualize all stages of metastatic seeding, including: tumor cell arrival; extravasation; growth and progression to micrometastases; as well as tumor microenvironment of metastasis function, the hallmark of hematogenous dissemination of tumor cells.

Unraveling the host's immune response to infection: Seeing is believing

“…For example, the chronic cranial window is permanently secured to the skull following a craniotomy to expose an area of the brain, allowing researchers to image the same location for up to a year . To date, chronic windows have been developed for the brain, skin, lymph node, liver, spleen, and other abdominal organs, and most recently, the lung . Although chronic windows can induce some inflammation when the window is implanted, using this technique to study chronic infections, such as tuberculosis or those seen in cystic fibrosis patients who are plagued by long‐term staphylococcal and Pseudomonas infections, would be of great interest to the medical community.…”

“…126 To date, chronic windows have been developed for the brain, skin, lymph node, liver, spleen, and other abdominal organs, and most recently, the lung. 126,127 Although chronic windows can induce some inflammation when the window is implanted, using this technique to study chronic infections, such as tuberculosis or those seen in cystic fibrosis patients who are plagued by long-term staphylococcal and…”

Frontiers in intravital multiphoton microscopy of cancer

“…These have allowed long‐term imaging of the mammary gland and the abdomen . Recently, a longitudinal imaging lung window was added to this list . This lung window made it possible for the first time to visualize tumor cell extravasation in real time (Figure E).…”

“…While elastin autofluorescence has been useful for ex vivo studies in the lung, so far, no IV‐MPM study of lung elastin has been reported. With the development of the lung imaging window (see section ), we can expect that more longitudinal studies will harness the autofluorescence properties of elastin, abundant in the lung.…”

“…Combined IV-MPM and FACS has also been used to analyze the fate of myeloid cells in lung metastases. 108 Although FACS is a high-throughput isolation technique that allows for the collection and robust analysis of specific cell types, it 103 requires tissue dissociation that separates cells from their microenvironment, leading to the loss of valuable contextual information. To isolate specific subpopulations of cells from tissue sections, laser capture microdissection (LCM) can be used.…”