Table 2.

Cell activity after freezing and recovering (%, $\overline{X}\pm \mathrm{S}\mathrm{D}$).

Cell type	hBMSC P3	pBABE-hBMSC	hPPE-hBMSC	F value	P value
Number (n)	5	5	5	—	—
Living cell rate (%)	89.90 ± 3.20	87.30 ± 3.26	88.08 ± 2.20	1.033	0.386

There were no significant differences among the three groups (P > 0.05), indicating that transfection had no effect on the morphology and proliferation of these cells. hPPE, human proenkephalin; hBMSC, human bone marrow stem cell; pBABE-hBMSC, the pBABE-hBMSC group; hPPE-hBMSC, the hPPE-hBMSC group.