SYNTHETIC MEMBRANE-RECEIVER COMPLEXES

1 . An enucleated erythroid cell comprising an exogenous polypeptide comprising thymidine phosphorylase (TYMP) or a functional fragment thereof,

wherein the enucleated erythroid cell is made by a process comprising introducing an exogenous nucleic acid encoding the exogenous polypeptide into a nucleated erythroid cell precursor.

2 . The enucleated erythroid cell of claim 1 , which comprises at least 1,000 copies of the exogenous polypeptide.

3 . The enucleated erythroid cell of claim 1 , wherein the exogenous polypeptide is intracellular.

4 . The enucleated erythroid cell of claim 1 , which is not a hypotonically loaded cell.

5 . The enucleated erythroid cell of claim 1 , wherein the exogenous polypeptide consists essentially of TYMP.

6 . The enucleated erythroid cell of claim 1 , wherein the exogenous polypeptide consists of TYMP.

7 . The enucleated erythroid cell of claim 1 , wherein the exogenous nucleic acid comprises DNA.

8 . The enucleated erythroid cell of claim 1 , wherein the exogenous nucleic acid comprises RNA.

9 . The enucleated erythroid cell of claim 1 , which is a reticulocyte.

10 . The enucleated erythroid cell of claim 1 , which is an erythrocyte.

11 . The enucleated erythroid cell of claim 1 , which lacks A and B antigens.

12 . The enucleated erythroid cell of claim 1 , wherein the nucleated erythroid cell precursor is a CD34+ hematopoietic stem cell.

13 . The enucleated erythroid cell of claim 1 , which is a human cell.

14 . A pharmaceutical composition comprising a plurality of the enucleated erythroid cells of claim 1 .

15 . The pharmaceutical composition of claim 14 , wherein at least about 90% of enucleated erythroid cells in the pharmaceutical composition comprise the exogenous polypeptide.

16 . A pharmaceutical composition comprising a plurality of the enucleated erythroid cells of claim 1 , wherein at least 70% of the cells in the pharmaceutical composition are the enucleated erythroid cells.

17 . A nucleated erythroid cell precursor comprising an exogenous polypeptide comprising TYMP or a functional fragment thereof, wherein the nucleated erythroid cell precursor was made by a process comprising introducing an exogenous nucleic acid encoding the exogenous polypeptide into the nucleated erythroid cell precursor.

18 . The nucleated erythroid cell precursor of claim 17 , wherein the exogenous polypeptide is intracellular.

19 . The nucleated erythroid cell precursor of claim 17 , which has been cultured after the introduction of the exogenous nucleic acid.

20 . A method of treating mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) in a subject in need thereof, comprising administering to the subject a pharmaceutical composition comprising a plurality of enucleated erythroid cells comprising an exogenous polypeptide comprising TYMP or a functional fragment thereof, wherein each of the enucleated erythroid cells of said plurality was made by a process comprising introducing an exogenous nucleic acid encoding the exogenous polypeptide into a nucleated erythroid cell precursor.

21 . The method of claim 20 , wherein the exogenous polypeptide is intracellular.

22 . A method of treating MNGIE in a subject in need thereof, comprising administering to the subject a pharmaceutical composition comprising a plurality of nucleated erythroid cell precursors comprising an exogenous polypeptide comprising TYMP or a functional fragment thereof, wherein each of the nucleated erythroid cell precursors of said plurality was made by a process comprising introducing an exogenous nucleic acid encoding the exogenous polypeptide into the nucleated erythroid cell precursor.

23 . The method of claim 22 , wherein the exogenous polypeptide is intracellular.

24 . The method of claim 22 , wherein the nucleated erythroid cell precursor has been cultured after the introduction of the exogenous nucleic acid.