Figure 6.

Microscopic images of MSCs using either polybrene or protamine sulfate with the pRRL vector system. Red fluorescence of the tdTomato marker protein expression and corresponding phase contrast microscopic images 6 days after lentiviral infection of the three different MSC populations A, B, C with the pRRL system. Control virus (Luc/pRRL) and the BDNF virus (BDNF/pRRL) were used for lentiviral modification of the MSCs either in the presence of 8 μg/ml polybrene or 50 μg/ml protamine sulfate. There are no notable differences in fluorescence intensity between viruses, polycations (polybrene and protamine sulfate) and MSC donors. Bar: 100 μm. Native hMSCs before lentiviral infection do not exhibit any red autofluorescence (data not shown)