A manifesto on the current state of dendritic cells in adoptive immunotherapy

Regulatory dendritic cell therapy in organ transplantation

Dendritic cells (DCs) are uniquely well equipped antigen (Ag)-presenting cells. Their classic function was thought to be that of potent initiators of innate and adaptive immunity to infectious organisms and other Ags (including transplanted organs). Evidence has emerged, however, that DCs have a central and crucial role in determining the fate of immune responses toward either immunity or tolerance. This dichotomous function of DCs, coupled with their remarkable plasticity, renders them attractive therapeutic targets for immune modulation. In transplantation, much recent work has focused on the ability of DCs to silence immune reactivity in an Ag-specific manner in the hope of preventing rejection and diminishing reliance on potentially harmful immunosuppressive agents. Experimental strategies have included in vivo targeting of DCs, as well as ex vivo generation of regulatory (or tolerogenic) DCs with subsequent reinfusion (i.e. cell therapy). Different approaches to 'program' DC toward tolerogenic properties include genetic (transgene insertion), biologic (differential culture conditions, anti-inflammatory cytokine exposure) and pharmacologic manipulation. Recent data suggest a promising role for pharmacologic treatment as a means of generating potent regulatory DCs and have further stimulated speculation regarding their potential clinical application. Herein, we discuss evidence that the potential of regulatory DC therapy is considerable and that there are compelling reasons to evaluate it in the setting of organ transplantation in the near future.

Will regulation be the death of cell therapy in the United States?

Advanced cell-based therapies are rapidly evolving and there is apparent increasing tension between regulation and introduction of new scientific advances. The model and concept of product development has introduced new challenges for laboratories developing cell-based therapies. The scale-up of experimental processes to production processes is an expensive but poorly compensated activity. The regulatory issues including personnel and facility requirements for manufacturing creates significant economic barriers to academic centers entering the field. As yet the model of product development envisioned by regulatory agencies is a patented commercial product to be manufactured by a company or its licensed manufacturers. The alternative model of advanced blood banks producing products may provide wider dissemination of products to patients. Although regulations have sometimes been perceived to be delaying advances, the regulatory agencies are evolving into a cooperative, supportive position that will ultimately speed the introduction of safe and effective cell-based therapies to broad clinical use. The vision for cell-based therapies needs scientific breadth and regulatory understanding to benefit the greatest number of patients.