The results of our previous studies in which we used the so-called strategy . chemotactic isolation to stromal - derived factor 1 ( called Stromal Cell Derived Factor 1 , SDF- 1 ) in combination with the technique of real-time PCR (Real Time PCR , RT- PCR) showed that there is a bone marrow cell population expressing CXCR4 + mRNA markers for early stem cells targeted tissue ( UTKM ) .