Optical High Content Nanoscopy of Epigenetic Marks Decodes Phenotypic Divergence in Stem Cells

While distinct stem cell phenotypes follow global changes in chromatin marks, single-cell chromatin technologies are unable to resolve or predict stem cell fates. We propose the first such use of optical high content nanoscopy of histone epigenetic marks (epi-marks) in stem cells to classify emergent cell states. By combining nanoscopy with epi-mark textural image informatics, we developed a novel approach, termed EDICTS (Epi-mark Descriptor Imaging of Cell Transitional States), to discern chromatin organizational changes, demarcate lineage gradations across a range of stem cell types and robustly track lineage restriction kinetics. We demonstrate the utility of EDICTS by predicting the lineage progression of stem cells cultured on biomaterial substrates with graded nanotopographies and mechanical stiffness, thus parsing the role of specific biophysical cues as sensitive epigenetic drivers. We also demonstrate the unique power of EDICTS to resolve cellular states based on epi-marks that cannot be detected via mass spectrometry based methods for quantifying the abundance of histone posttranslational modifications. Overall, EDICTS represents a powerful new methodology to predict single cell lineage decisions by integrating high content super-resolution nanoscopy and imaging informatics of the nuclear organization of epi-marks.National Institutes of Health (U.S.) (Grant GM110174

Diagnostic Enigma: Spindle Cell Sarcoma of the Aorta Presenting as Pulmonary Embolism and Chronic Anaemia

Primary aortic sarcoma is a rare and aggressive malignancy with only approximately 190 cases reported in the literature. While angiosarcoma and intimal sarcomas represent an estimated 67.7% of malignant aortic tumours, spindle cell sarcomas are even more exclusive, consisting of only 0.9% of malignant aortic tumours. Differentiated from other malignant aortic tumours, spindle cell sarcomas are of mesenchymal origin and usually express vimentin and osteopontin. Clinical presentations are variable and nonspecific, ranging from back pain, abdominal pain or elevated blood pressure, misleading to differentials like pulmonary emboli or aortic aneurysms such as in our case here. In this article, we discuss the finding of an extremely rare aortic sarcoma masquerading as a pulmonary embolism. The patient underwent surgical resection; however, the course was complicated by the development of brain metastases and intracranial haemorrhage. The literature is expanding regarding the evolution of adjuvant chemotherapy and radiation therapy in the treatment of these patients. The exact pathogenesis of spindle cell sarcomas is unknown but thought to be related to the MDM2-p53 pathway. The development of spindle cell sarcomas may be related to Li-Fraumeni syndrome, which should be on the differential for these patients. This case highlights the importance of identifying aortic sarcomas in patients who present with signs and symptoms of peripheral embolization as the diagnosis can be easily misconstrued for thrombus or aortic aneurysm, leading to a delay in proper and timely management. We herein emphasize that aortic sarcomas should be included in the clinician’s working differential due to the poor prognosis and outcomes that these aggressive tumours carry