EFFECTS OF HETEROLOGOUS HEMATOPOIETIC CYTOKINES ON IN-VITRO DIFFERENTIATION OF CULTURED PORCINE INNER CELL MASSES

An exogenous supply of hematopoietic cytokines is essential for mainta ining murine embryonic stem (ES) cells in a proliferative yet undiffer entiated state. Recently, it was demonstrated that hematopoietic cytok ines utilize the gp130 signal transduction pathway to maintain this ph enotype, although their involvement toward maintaining porcine ES cell pluripotency has not been established. Therefore, the objective of th is study was to determine the effectiveness of several heterologous he matopoietic cytokines at maintaining the isolated porcine inner cell m asses (pICM) in an undifferentiated state. pICMs (day 7) were isolated by immunosurgery and cultured 4 days in one of six treatments: contro l medium, human leukemia inhibitory factor (hLIF; 1,000 u/ml), human i nterleukin-6 (hIL-6; 100 ng/ml), hIL-6 + hIL-6 soluble receptor (hlL6 + sR; 100 ng/ml + 2.5 mu g/ml), human oncostatin M (hOSM; 100 ng/ml), or rat ciliary neurotrophic factor (rCNTF; 100 ng/ml). All cytokines w ere prepared in Dulbecco's Modified Eagle's Medium/Ham's F-10 (1:1)-ba sed medium. Morphology of pICMs was evaluated on a scale of 1 (fully u ndifferentiated) to 5 (fully differentiated) at 24-h intervals. Differ entiation was significantly lower on day 2 for rCNTF vs, hLIF cultured pICMs (2.07 +/- 0.15 vs. 2.70 +/- 0.16; P < 0.05). Furthermore, addit ion of rCNTF gave the lowest overall mean differentiation score (2.53 +/- 0.15). However, none of the cytokines significantly delayed differ entiation over controls for the 4-day culture period (P > 0.05). Since these heterologous cytokines were unable to inhibit differentiation, it is unlikely they will be beneficial towards isolating porcine ES ce ll lines under current conditions. Future work with homologous cytokin es and dose effects may prove more beneficial. (C) 1996 Wiley-Liss, In c.