tailieunhanh - Chapter 065. Gene Therapy in Clinical Medicine

Gene transfer is a novel area of therapeutics in which the active agent is a nucleic acid sequence rather than a protein or small molecule. Because delivery of naked DNA or RNA to a cell is an inefficient process, most gene transfer is carried out using a vector, or gene delivery vehicle. These vehicles have generally been engineered from viruses by deleting some or all of the viral genome and replacing it with the therapeutic gene of interest under the control of a suitable promoter (Table 65-1). . | Chapter 065. Gene Therapy in Clinical Medicine Gene transfer is a novel area of therapeutics in which the active agent is a nucleic acid sequence rather than a protein or small molecule. Because delivery of naked DNA or RNA to a cell is an inefficient process most gene transfer is carried out using a vector or gene delivery vehicle. These vehicles have generally been engineered from viruses by deleting some or all of the viral genome and replacing it with the therapeutic gene of interest under the control of a suitable promoter Table 65-1 . Gene transfer strategies can be described in terms of three essential elements 1 a vector 2 a gene to be delivered and 3 a relevant target cell to which the DNA or RNA is delivered. The series of steps in which the donated DNA enters the target cell and begins expression is referred to as transduction. Gene delivery can take place in vivo in which the vector is directly injected into the patient or in the case of hematopoietic and some other target cells ex vivo with removal of the target cells from the patient followed by return of the modified autologous cells after gene transfer in the laboratory. The latter approach offers opportunities to integrate gene transfer techniques with cellular therapies Chap. 67 . Table 65-1 Characteristics of Gene Delivery Vehicles Viral Vectors Non-Viral Vectors Feat Retr Lent Ade AAV Hu HSV SV- Alph Transpos Lipo Nake Site- ures ovir ivira nov ma -1 40 aviru on Trans som d Spec al l iral n ses posase es DNA ific Foa System Integ my rase Viru s Viral RNA RNA DN DNA RN DNA DNA RNA N A N A N A N A geno me A A Cell Yes G1 No No No No No No No No No No divisi pha on se requi reme nt Pack 8 kb 8 kb 8- 5 kb 40- 5 kb 5 kb Undetermi Unde Undet Unde aging 30 kb 150 ned termi ermin termi limita kb kb probably ned ed ned tion large prob proba prob ably bly ably large large large Imm Few Few Ext Few Few Few Few Few No No No No une ensi resp ve onse s to vecto r Geno Yes Yes Poo Poor in reco mbi nant .