Exploring Metabolic Configurations of Single Cells within Complex Tissue Microenvironments.

Over the past years, plenty of evidence has emerged illustrating how metabolism supports many aspects of cellular function and how metabolic reprogramming can drive cell differentiation and fate. Here, we present a method to assess the metabolic configuration of single cells within their native tissue microenvironment via the visualization and quantification of multiple enzymatic activities measured at saturating substrate conditions combined with subsequent cell type identification. After careful validation of the approach and to demonstrate its potential, we assessed the intracellular metabolic configuration of different human immune cell populations in healthy and tumor colon tissue. Additionally, we analyzed the intercellular metabolic relationship between cancer cells and cancer-associated fibroblasts in a breast cancer tissue array. This study demonstrates that the determination of metabolic configurations in single cells could be a powerful complementary tool for every researcher interested to study metabolic networks in situ.

Human platelet lysate is a feasible candidate to replace fetal calf serum as medium supplement for blood vascular and lymphatic endothelial cells.

BACKGROUND AIMS: As angiogenic and lymphangiogenic key players, endothelial cells (ECs) are promising candidates for vascular regenerative therapies. To culture ECs in vitro, fetal calf serum (FCS) is most often used. However, some critical aspects of FCS usage, such as possible internalization of xenogeneic proteins and prions, must be considered. Therefore, the aim of this project was to determine if human platelet lysate (hPL) is a suitable alternative to FCS as medium supplement for the culture of blood vascular and lymphatic endothelial cells. METHODS: The usability of hPL was tested by analysis of endothelial surface marker expression, metabolic activity and vasculogenic potential of outgrowth ECs (OECs), human umbilical vein ECs (HUVECs), and lymphatic ECs (LECs). RESULTS: Expression of EC markers CD31, VEGFR2, VE-cadherin and CD146 did not differ significantly between the EC types cultured in FCS or hPL. In addition, OECs, HUVECs and LECs formed tube-like structures on Matrigel when cultured in hPL and FCS. With the use of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid assays, we found that the metabolic activity of OECs and LECs was slightly decreased when hPL was used. However, HUVECs and LECs did not show a significant decrease in metabolic activity, and HUVECs showed a slightly higher activity at low seeding densities. CONCLUSIONS: The use of hPL on different EC types did not reveal any substantial negative effects on EC behavior. Thus, hPL appears to be a favorable candidate to replace FCS as a medium supplement in the culture of ECs.