Enhancement of insulin-producing cell differentiation from embryonic stem cells using pax4-nucleofection method.
OBJECTIVE
To enhance the differentiation of insulin producing cell (IPC) ability from embryonic stem (ES) cells in vitro.


METHODS
Four-day embryoid body (EB)-formatted ES cells were dissociated as single cells for the followed plasmid DNA delivery. The use of Nucleofector electroporator (Amaxa biosystems, Germany) in combination with medium-contained G418 provided a high efficiency of gene delivery for advanced selection. Neucleofected cells were plated on the top of fibronectin-coated Petri dishes. Addition of Ly294002 and raised the glucose in medium at 24 h before examination. The differentiation status of these cells was monitored by semi-quantitative PCR (SQ-PCR) detection of the expression of relative genes, such as oct-4, sox-17, foxa2, mixl1, pdx-1, insulin 1, glucagons and somatostatin. The percentage of IPC population on d 18 of the experiment was investigated by immunohistochemistry (IHC), and the content/secretion of insulin was estimated by ELISA assay. The mice with severe combined immunodeficiency disease (SCID) pretreated with streptozotocin (STZ) were used to eliminate plasma glucose restoration after pax4+ ES implantation.


RESULTS
A high efficiency of gene delivery was demonstrated when neucleofection was used in the present study; approximately 70% cells showed DsRed expression 2 d after neucleofection. By selection of medium-contained G418, the percentage of DsRed expressing cells kept high till the end of study. The pancreatic differentiation seemed to be accelerated by pax4 nucleofection. When compared to the group of cells with mock control, foxa2, mixl1, pdx1, higher insulin and somatostatin levels were detected by SQ-PCR 4 d after nucleofection in the group of pax4 expressing plasmid delivery. Approximately 55% of neucleofected cells showed insulin expression 18 d after neucleofection, and only 18% of cells showed insulin expression in mock control. The disturbance was shown by nucleofected pax4 RNAi vector; only 8% of cells expressed insulin 18 d after nucleofection. A higher IPC population was also detected in the insulin content by ELISA assay, and the glucose dependency was demonstrated in insulin secretion level. In the animal model, improvement of average plasma glucose concentration was observed in the group of pax-4 expressed ES of SCID mice pretreated with STZ, but no significant difference was observed in the group of STZ-pretreated SCID mice who were transplanted ES with mock plasmid.


CONCLUSIONS
Enhancement of IPC differentiation from EB-dissociated ES cells can be revealed by simply using pax4 expressing plasmid delivery. Not only more IPCs but also pancreatic differentiation-related genes can be detected by SQ-PCR. Expression of relative genes, such as foxa 2, mixl 1, pdx-1, insulin 1 and somatostatin after nucleofection, suggests that pax4 accelerates the whole differentiation progress. The higher insulin production with glucose dependent modulation suggests that pax4 expression can drive more mature IPCs. Although further determination of the entire mechanism is required, the potential of pax-4-nucleofected cells in medical treatment is promising.
Lin
Han-Tso
HT
Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, China.
Kao
Chung-Lan
CL
Lee
Kun-Hsiung
KH
Chang
Yuh-Lih
YL
Chiou
Shih-Hwa
SH
Tsai
Fu-Ting
FT
Tsai
Tung-Hu
TH
Sheu
Dey-Chyi
DC
Ho
Larry L T
LL
Ku
Hung-Hai
HH
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D051542:Hepatocyte Nuclear Factor 3-beta / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007328:Insulin / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000502:physiology*; D016133:Polymerase Chain Reaction / Q000379:methods; D013004:Somatostatin / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014162:Transfection / Q000379:methods*
D001786:Blood Glucose; C496503:Foxa2 protein, mouse; D018398:Homeodomain Proteins; D007328:Insulin; C464781:Mixl1 protein, mouse; D050814:Octamer Transcription Factor-3; D051761:Paired Box Transcription Factors; C110218:Pax4 protein, mouse; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; D051542:Hepatocyte Nuclear Factor 3-beta; D013004:Somatostatin