Cell Tracking

Cell surface engineering has been playing an important role in cell tracking by increasing the sensitivity of imaging. As a professional cell surface engineering services provider, Creative Biolabs is experienced and we have accomplished hundreds of customer-satisfied projects.

Introduction

Tracking the transport and destination of cells systemically or locally injected into a body is necessary to ascertain their homing and engraftment. As such, efforts are being made to image transplanted cells using noninvasive bioimaging approaches, including magnetic resonance imaging, positron emission tomography, optoacoustic tomography, and luminescence/fluorescence-based in vivo imaging systems. To increase imaging sensitivity, cells are labeled with a series of molecules or nanoparticles to generate positive or negative contrast in clinical images captured with the appropriate bioimaging instrument.

Methods and Applications

• Magnetic Resonance Imaging Tracking and Contrast Agents

Magnetic resonance imaging is a non-invasive method to diagnose disease and tissue defects in the clinic by converting the relaxation rates of protons on the water in the body into 3D images of organs and tissue. Despite the multiple merits of magnetic resonance imaging, such as high-resolution imaging, magnetic resonance imaging has low sensitivity in differentiating between transplanted cells and healthy tissue. Contrast agents that can modulate the relaxation rate of water protons are being engineered to label transplanted cells, thereby highlighting in magnetic resonance images the tissue where cells are accumulated. Magnetic resonance imaging contrast agents currently used in clinical settings, with approval by the FDA, include gadolinium (a positive contrast agent) and superparamagnetic iron oxide nanoparticles (a negative contrast agent).

Fig.1 Schematic of trivalent 1,4,7,10-tetrazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)−gadolinium(III) complex coating a cell surface and following enhancement of the T₁-weighted magnetic resonance imaging result. (Park, 2018)

• Positron Emission Tomography Imaging

Positron emission tomography (PET) is a whole-body-imaging method used to monitor the function of organs and tissues. One radio tracker extensively used in imaging is 18F-fluorodeoxy-D-glucose. This radio tracker has been used to monitor cellular glucose uptake, which is more rapid in cancer. In another example, the 18F-based molecule was used to evaluate the effects of warm ischemic stress on islets in the early stage of transplantation to the liver.

• Optoacoustic Imaging

On the basis of the photoacoustic effect, optoacoustic imaging generates images by detecting ultrasonic waves produced by the interaction of a nonionizing laser pulse with irradiated tissue. The energy absorbed into tissue is transformed into heat, which results in wideband ultrasonic emission. The degree of energy absorption is associated with physiological conditions, including the local concentration of hemoglobin and oxygen. Gold nanoparticles with controlled sizes and shapes have been used as exogenous contrast agents in optoacoustic imaging because their optical absorption can be tuned by the surface plasmon resonance effect. Gold nanoparticles can be functionalized to target specific tissue; for instance, antibody conjugation allowed selective binding of epithelial growth factor receptors and the imaging of human epithelial cancer cells.

• In Vivo Imaging with Fluorescent Labeling

Commercially available in vivo imaging systems generate 3D bioimages with spectra from fluorescent or luminescent probes coupled with molecules or cells of interest. Many preclinical studies have utilized this imaging system to analyze the biodistribution of therapeutic cells post-transplantation.

Fig.2 In vivo imaging system that captures near-infrared fluorescence (NIRF) of the Cy5-modified human adipose-derived mesenchymal stem cells in the ischemic hindlimb. (Park, 2018)

Services at Creative Biolabs

Focusing on surface engineering research for years, Creative Biolabs has accumulated rich experience and we have gradually developed our own technology platform. With advanced facilities and excellent scientific staff, our platform offering high-quality cell surface engineering services including but not limited to:

• Cell-Covalent Conjugation Service
• Cell-Noncovalent Physical Bioconjugation Service
• Cell-Nucleic Acids Conjugate Service

With professional expertise and strong foundations, Creative Biolabs is eager to bring every client top-rated customer experience. If you are interested in cell surface engineering services, please don’t hesitate to contact us for more information.

Reference

1. Park, J.; et al. Engineering the surface of therapeutic "living" cells. Chem Rev. 2018, 118(4): 1664-1690.