In vivo tracking techniques for cellular regeneration, replacement, and redirection

Abstract

Cellular therapy can be defined as the transplantation of living cells for the treatment of medical conditions. Three main objectives of cellular therapy are regeneration of damaged tissue, replacement of function by secretion of biologically active molecules, and redirection of aberrant processes. Given the complex nature of these approaches, in vivo tracking of the transplanted cells is critical to evaluate their potential benefit and to optimize treatment strategies. Recent advances are reviewed that enable in vivo cell tracking as an important adjunct to implement cellular therapy in clinical practice.

FIGURE 1

Cellular therapy offers hope for treatment of today’s most prevalent diseases, including cancer and cardiovascular diseases. Transplanted therapeutic cells essentially perform 3 main roles: regeneration, replacement, and redirection. Imaging protocols should serve different functions in each of these, that is, emphasizing specific aspects of cellular therapy in order to optimize therapeutic strategies. Important factors for consideration are sensitivity, patient discomfort, exposure to radiation, and minimization of cost.

FIGURE 2

In vivo scintigraphy and MRI cell tracking of dendritic cells labeled with superparamagnetic iron oxide and ¹¹¹In after intranodal injection. (Left) Gradient echo coronal MR image showing 2 left inguinal lymph nodes with hypointense signal area 48 h after injection. (Right) Corresponding scintigraphic image including quantification of relative cellular distribution among multiple lymph nodes. Arrows indicate 2 parts that belong to same lymph node.