Raman imaging unveils heme uptake in endothelial cells

Area of Science:

• Biomedical Science
• Cellular Biology
• Oxidative Stress Research

Background:

• Heme released from damaged red blood cells (RBCs) can cause cell injury.
• Endothelial cells (ECs) play a crucial role in preventing heme-induced inflammation through uptake.
• Understanding heme uptake mechanisms is vital for managing inflammatory conditions.

Purpose of the Study:

• To investigate and visualize the process of heme uptake by endothelial cells.
• To characterize the iron oxidation state within heme during cellular uptake.
• To provide Raman-based evidence of heme uptake in both in vitro and ex vivo models.

Main Methods:

• Utilized label-free Raman imaging with dual excitation wavelengths.
• Employed Human Aortic Endothelial Cells (HAECs) as an in vitro model.
• Examined heme uptake in ex vivo murine aortic tissues from healthy and atherosclerotic mice (ApoE/LDLR-/-).

Main Results:

• Demonstrated heme uptake by HAECs in vitro under controlled heme concentrations.
• Visualized heme uptake in ex vivo aortic tissues from both healthy and atherosclerotic mice.
• Characterized the oxidation state of iron within the heme molecule during uptake using Raman spectroscopy.

Conclusions:

• Confirmed heme uptake by endothelial cells as a protective mechanism against heme toxicity.
• Provided the first in situ, label-free Raman-based evidence of heme uptake by ECs.
• Established Raman imaging as a powerful tool for studying heme-endothelial cell interactions in various physiological and pathological contexts.