Radiolabeling stem cells, an urgent need in nuclear medicine.

Embryonic and adult stem cells are today being considered as ‘good’ stem cells crucial for therapy in various disorders and as a possible alternative to obtaining organ transplants in coronary artery disease, renal failure, diabetes, liver failure and blindness to name but a few. Documenting the survival of these stem-cells after introduction and as well as their subsequent bio-distribution is of fundamental importance. Similarly cancer stem cells are today being recognized as ‘bad’ stem cells responsible for cancer recurrence & metastases after successful treatment of the primary. These harmful stem cells similarly need to be characterized as regards their surface antigens both from the point of view of imaging to document their presence in a particular patient and also as the preferred antigen against which antibodies native or radio-labeled or peptides can be deployed for therapy. It is suggested that both single photon as well as positron emitting tracers for both good and bad stem cells should constitute a high priority area for nuclear medicine research. The relevant literature is reviewed and some experimental leads and approaches outlined.