The multicolor and multiplexing capabilities of semiconductor quantum dots (QDs) are most promising for improving the sensitivity and specificity of in vitro molecular and cellular diagnostics. Here, we report the use of multiplexed QDs and wavelength-resolved imaging to detect and characterize a class of low-abundant tumor cells in Hodgkin’s lymphoma. Known as the Hodgkin’s and Reed-Sternberg (HRS) cells, this class of malignant cells is a pathological hallmark in clinical diagnosis, but it comprises only about 1% of the heterogeneous infiltrating cells in lymph node tissues. To overcome this cellular heterogeneity and rarity problem, we have developed multicolor QD–antibody conjugates to simultaneously detect a panel of four protein biomarkers (CD15, CD30, CD45, and Pax5) directly on human tissue biopsies. This multiplexing approach allows rapid detection and differentiation of rare HRS cells from infiltrating immune cells such as T and B lymphocytes. We have also carried out clinical translation studies involving six confirmed Hodgkin’s lymphoma patients, two suspicious lymphoma cases, and two patients with reactive lymph nodes (but not lymphoma). The results indicate that a distinct QD staining pattern (CD15 positive, CD30 positive, CD45 negative, and Pax5 positive) can be used to not only detect Hodgkin’s lymphoma but also differentiate it from benign lymphoid hyperplasia.
Tumor heterogeneity is one of the most important and challenging problems not only in studying the mechanisms of cancer development but also in developing therapeutics to eradicate cancer cells. Here we report the use of multiplexed quantum dots (QDs) and wavelength-resolved spectral imaging for molecular mapping of tumor heterogeneity on human prostate cancer tissue specimens. By using a panel of just four protein biomarkers (E-cadherin, high-molecular-weight cytokeratin, p63, and α-methylacyl CoA racemase), we show that structurally distinct prostate glands and single cancer cells can be detected and characterized within the complex microenvironments of radical prostatectomy and needle biopsy tissue specimens. The results reveal extensive tumor heterogeneity at the molecular, cellular, and architectural levels, allowing direct visualization of human prostate glands undergoing structural transitions from a double layer of basal and luminal cells to a single layer of malignant cells. For clinical diagnostic applications, multiplexed QD mapping provides correlated molecular and morphological information that is not available from traditional tissue staining and molecular profiling methods.