Table 1.
Achievements and limitations of the CT approach.
| Achievements | Limitations | |
|---|---|---|
| Donor cell line (CHO 1/HSA 2) |
Single-chromosome universal donor cell line for the treatment of the disorder mapping to the specific chromosome. Cell line able to form microcells. |
Demonstrated only for X-linked disorders (CHO/HSAX). |
| Recipient cell line (iPSCs 3) |
Cells with a normal diploid genome, indefinite growth, pluripotency and capacity to differentiate into various tissues. | Long term in vitro culturing could accumulate mutations. |
| Fusion (retro-MMCT 4) |
Retro-MMCT is based on murine leukemia virus envelope protein (Env) mediated fusion: less cytotoxic and more efficient compared to classic PEG 5 based MMCT fusion. | It is necessary to infect the donor cells with a lentivirus carrying the Env gene. |
| Selection (drug selection) |
Use of an endogenous selectable gene (i.e., HPRT 6) or classical drug selection. | Endogenous selection system limited for a few chromosomes. |
| Chromosome loss (spontaneous loss) |
Spontaneous loss of trisomic chromosomes without genomic manipulation. | Alternatively, more complex approaches could be used to drive the chromosome loss. |
1 CHO: Chinese Hamster Ovary cell line; 2 HSA: Homo sapiens chromosome; 3 iPSCs: induced pluripotent stem cells; 4 MMCT: microcell-mediated chromosome transfer; 5 PEG: Polyethylene Glycol; 6 HPRT: Hypoxanthine-guanine phosphoribosyltransferase.