*3.1. Suicide Gene Strategy Enabled the Depletion of Bone Marrow-Derived Fibrocytes*

TAA- and VCV-treatment was well tolerated during the animal experiments. After reconstitution from bone marrow transplantation, mice gained weight steadily, regardless of group affiliation. Basic observational data are provided in Supplementary Figure S1. Due to drastic weight loss, one out of the 32 mice was euthanized ahead of schedule. A subsequently performed autopsy of the euthanized mouse remained inconclusive, yet confirmed the successful reconstitution of bone marrow.

RNA in situ hybridization was performed on liver sections to visualize the suicide gene strategy's success. Bone marrow-derived fibrocytes were identified by the simultaneous expression of *Ptprc* (CD45) and *Col1a1* mRNA (collagen type I α-1 chain, Figure 1b). A considerable amount of fibrocytes, most frequently located in the periportal area and interportal septi, was detected in mice of the control group. While single cells remained, a marked reduction of the number of fibrocytes was observed in mice which received Col-HSV-TK bone marrow (Figure 1b, bottom).
