• human mesenchymal stem cells;
  • 5-fluorouracil;
  • cellular therapy;
  • retrovirus vector;
  • bystander effect



Previously, we validated capability of human adipose tissue-derived mesenchymal stem cells (AT-MSC) to serve as cellular vehicles for gene-directed enzyme prodrug molecular chemotherapy. Yeast fusion cytosine deaminase : uracil phosphoribosyltransferase expressing AT-MSC (CDy-AT-MSC) combined with systemic 5-fluorocytosine (5FC) significantly inhibited growth of human colon cancer xenografts. We aimed to determine the cytotoxic efficiency to other tumour cells both in vitro and in vivo.


CDy-AT-MSC/5FC-mediated proliferation inhibition against a panel of human tumour cells lines was evaluated in direct and indirect cocultures in vitro. Antitumour effect was tested on immunodeficient mouse model in vivo.


Although culture expansion of CDy-AT-MSC sensitized these cells to 5FC mediated suicide effect, expanded CDy-AT-MSC/5FC still exhibited strong bystander cytotoxic effect towards human melanoma, glioblastoma, colon, breast and bladder carcinoma in vitro. Most efficient inhibition (91%) was observed in melanoma A375 cell line when directly cocultured with 2% of therapeutic cells CDy-AT-MSC/5FC. The therapeutic paradigm of the CDy-AT-MSC/5FC system was further evaluated on melanoma A375 xenografts on nude mice in vivo. Complete regression in 89% of tumours was achieved when 20% CDy-AT-MSC/5FC were co-injected along with tumour cells. More importantly, systemic CDy-AT-MSC administration resulted in therapeutic cell homing into subcutaneous melanoma and mediated tumour growth inhibition.


CDy-AT-MSC capability of targeting subcutaneous melanoma offers a possibility to selectively produce cytotoxic agent in situ. Our data further demonstrate beneficial biological properties of AT-MSC as a cellular vehicle for enzyme/prodrug therapy approach to molecular chemotherapy. Copyright © 2008 John Wiley & Sons, Ltd.