Labeling fibroblasts with biotin‐BSA‐GdDTPA‐FAM for tracking of tumor‐associated stroma by fluorescence and MR imaging

Abstract

Fibroblasts at the tumor-host interface can differentiate into myofibroblasts and pericytes, and contribute to the guidance and stabilization of endothelial sprouts. After intravenous administration of biotin-BSA-GdDTPA-FAM in mice with subcutaneous MLS human ovarian carcinoma tumors, the distribution of the macromolecular MRI/optical contrast material was confined to blood vessels in normal tissues, while it co-registered with ␣SMA-positive stroma tracks within the tumor. These ␣SMA-positive tumor-associated myofibroblasts and pericytes showed uptake of the contrast material into intracellular granules. We evaluated the use of this contrast material for in vitro labeling of tumor fibroblasts as an approach for tracking their involvement in angiogenesis. Fluorescence microscopy demonstrated internalization of the contrast material, and MRI revealed a significant increase in the R 1 relaxation rate of labeled fibroblasts. R 1 not only remained elevated for 2 weeks in culture, it also increased with cell proliferation, indicating prolonged retention of the contrast material and subsequent intracellular processing and redistribution of the material, and thereby enhancing MR contrast. Moreover, cells that were labeled ex vivo with MR contrast material and co-inoculated with tumor cells in mice were detected in vivo by MRI. Uptake of the contrast material was suppressed by nystatin, suggesting internalization by caveolae-mediated endocytosis. This study shows that labeling of fibroblasts with biotin-BSA-GdDTPA-FAM is feasible and would allow noninvasive in vivo tracking of fibroblasts during tumor angiogenesis and vessel maturation. Magn Reson Med 54:789 -797, 2005.

In vivo Imaging of the Systemic Recruitment of Fibroblasts to the Angiogenic Rim of Ovarian Carcinoma Tumors

“…MRI tracking of cell recruitment was achieved by labeling the fibroblasts with biotin-BSA-GdDTPA. The prolonged in vivo visibility of the signal arising from biotin-BSA-GdDTPAloaded fibroblasts is consistent with our previous in vitro studies (43) and enabled serial in vivo follow-up of fibroblast migration and recruitment to the tumor. Local and systemic recruitment of fibroblasts to s.c. ovarian carcinoma xenografts was detected by MRI and validated by in vivo near-IR imaging, revealing labeled fibroblasts at the tumor region, whereas no labeled cells could be detected in the contralateral tumor-free limb or in limbs of tumorfree mice.…”

“…We have previously reported the short term (1-2 days) in vivo MRI 43). Here, we evaluated the feasibility for prolonged MRI tracking of biotin-BSA-GdDTPA-labeled fibroblasts (Table 1, Exp II).…”

“…We have previously shown that infiltration of myofibroblasts can contribute to stabilization of the neovasculature by expression of angiopoietin-1 and angiopoietin-2, and that their infiltration to the tumor provides the switch for exit from dormancy of implanted ovarian carcinoma spheroids (8,9). To allow tracking of the recruitment of fibroblasts to tumors by MRI, we used the endogenous caveola-mediated uptake of albumin by fibroblasts to load cells with biotin-BSA-GdDTPA (43).…”

“…Recently, MRI was applied for tracking of endothelial precursor cells (EPC) that are involved in tumor angiogenesis and vascular remodeling using iron oxide nanoparticles (40,41) and Gd-HPDO3A caged in apoferritin (42). We reported recently the use of biotin-bovine serum albumin (BSA)-gadolinium-diethylenetriaminepentaacetic acid (GdDTPA) for ex vivo labeling of tumor fibroblasts (43). In the study reported here, in vivo MRI and near-IR imaging allowed detection of the recruitment of i.p.…”

Mesenchymal Stem Cell-Derived Microvesicles Protect Against Acute Tubular Injury

“…The adipogenic, osteogenic, and chondrogenic differentiation ability of MSC was determined as described previously. 34 Human fibroblasts, isolated from dermas as described 35 and used as control, were maintained in DMEM (Sigma) with 10% FCS (Euroclone, Wetherby, UK). …”